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  • 1.
    Ahmad, Nawaz
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. Policy Wing, Ministry of Petroleum and Natural Resources, Government of Pakistan, Pakistan.
    Wörman, Anders
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.
    Bottacin-Busolin, Andrea
    Sanchez-Vila, Xavier
    Reactive transport modeling of leaking CO2-saturated brine along a fractured pathway2015In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 42, p. 672-689Article in journal (Refereed)
    Abstract [en]

    One concern regarding the underground storage of carbon dioxide (CO2) is its potential leakage from reservoirs. Over short period of time, the leakage risk is related mainly to CO2 as a separate supercritical fluid phase. However, over longer periods upon complete dissolution of injected CO2 in the fluid, the leakage risk is associated with dissolved phase CO2. Over the geological time scales, large-scale groundwater motion may cause displacement of brine containing dissolved CO2 along the conducting pathways. In this paper, we present a comprehensive modeling framework that describes the reactive transport of CO2-saturated brine along a fracture in the clay caprock based on the future, hypothetical leakage of the dissolved phase CO2. This study shows that the transport of leaked dissolved CO2 is significantly retarded by a combination of various physical and geochemical processes, such as mass exchange between conducting fracture and the neighboring rock matrix through molecular diffusion, sorption and calcite dissolution in the rock matrix. Mass stored in aqueous and adsorbed states in the rock matrix caused retention of dissolved CO2 along the leakage pathway. Calcite dissolution reaction in the rock matrix resulted in consumption of leaking dissolved CO2 and reduced its mass along the leakage pathway. Consumption and retention of dissolved CO2 along the leakage pathway have important implications for analyzing the potential reduction of CO2 fluxes from storage reservoirs over large periods and long travel pathways.

  • 2.
    Alam, M.S.
    et al.
    Memorial University of Newfoundland, Canada.
    Ahmed, Kazi Matin
    University of Dhaka, Bangladesh.
    Hasan, M.A.
    University of Dhaka, Bangladesh.
    Hossain, Muhammed
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Controls of sedimentary facies on arsenic mobilization in shallow aquifers of the Matlab North Upazila, southeastern Bangladesh2013Conference paper (Other academic)
    Abstract [en]

    Groundwater extracted from shallow (<100 m bgl) Holocene alluvial aquifers, is the primary source of drinking water in Matlab North Upazila, Southeast Bangladesh. The distribution of lithofacies and its relation to hydrochemistry in such heterogeneous deposits are of fundamental importance for the analysis of groundwater quality. Aquifer sediment samples were collected from 48 locations throughout the study area. Lithofacies distribution was characterized using grain size and sediment colors. Channel fills (sandy) and over bank (silt-clay) deposits the two main lithofacies groups, were identified. These sandy deposits represent an active meandering river or channel fills sediment sequence, which are usually capped by silts and clays of an over bank sediment sequence. All the collected sediments samples were generalized and subdivided based on four distinct color variations, such as Black, White, Off-white, and Red according to Munsell color chart and water-well drillers’ perception.

    Mineral compositions showed variability with the sediment color and grain size. Red and off-white sediments contain fewer amounts of metastable minerals (hornblende, actinolite, kyanite and pyroxenes etc.) than that of black sediments, whereas black sediments contain higher amount of biotite. The relatively high content of biotite and other dark colored ferromagnesian minerals are responsible for the black and grayish color of these sediments. Ferruginous coating on silicates, particularly on quartz grains, gives the red and off-white coloration. Based on the available information regarding sediment colors of aquifers in which tubewell screens were placed, 44 domestic hand pumped tubewells (HTWs) were selected for water sampling. The groundwater abstracted from black sediments of shallow aquifer showed higher concentrations in DOC (median: 5.81 mg/L), dissolved NH

    4+ (median: 3.47 mg/L), PO43- (median: 1.36 mg/L), Fe (median: 4.87 mg/L), As (median: 252.53 μg/L) and relatively low Mn (median: 0.54 mg/L) and SO42-(median: 0.59 mg/L) concentrations, whereas groundwater abstracted from off-white and red sediments of shallow aquifer showed lower concentrations in DOC (median: 1.95 and 1.71 mg/L, respectively), dissolved NH4+ (median: 0), PO43- (median: 0.14 and 0.04 mg/L, respectively), Fe (median: 2.25 and 0.63 mg/L, respectively), As (median: 17.36 and 15.05 μg/L, respectively) and relatively high Mn+2 (median: 1.12 and 1.15 mg/L, respectively) and SO42- (median: 0.79 and 0.78 mg/L, respectively) concentrations. The water samples collected from black sediments (median Eh: 211 mV) indicated most reducing environment, followed by white (median Eh: 227 mV), whereas off-white and red sediments (median Eh: 268 and 274 mV) signified less reducing environment. The study supports that the sediment colors in shallow aquifer can be a reliable indicator of high and low-As concentrations and can be a useful tool for local drillers to target arsenic safe aquifers.

  • 3.
    Alemrajabi, Mahmood
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Forsberg, Kerstin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Korkmaz, Kivanc
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Isolation of rare earth element phosphate precipitate in the nitrophosphate process for manufacturing of fertilizer2016In: IMPC 2016 - 28th International Mineral Processing Congress, Canadian Institute of Mining, Metallurgy and Petroleum , 2016Conference paper (Refereed)
    Abstract [en]

    In the present study, the recovery of rare earth elements (REE) in the nitrophosphate process of fertilizer production is investigated. The apatite has been recovered from iron ore tailings by flotation. After digestion of apatite in concentrated nitric acid, Ca(NO3)2.4H2O is first separated by cooling crystallization and then the REEs are recovered by precipitation. Optimum conditions in these steps have been determined in a previous study. The precipitate mainly consists of CaHPO4.2H2O and REE phosphates. In the present study, selective dissolution and re-precipitation have been studied in order to obtain a precipitate that is more concentrated in REEs. The precipitate was selectively dissolved in nitric and phosphoric acid at different acidities (pH 6 to 0) with the liquid /solid ratio of 100 mL/g. It is shown that most of the CaHPO4.2H2O and other calcium containing compounds will be dissolved at pH 2 while the REE phosphates are not dissolved above a pH of approximately 2. Thus, by partial dissolution of the REE precipitate at pH 2.5 most of the solid calcium phosphates will be dissolved and the remaining solid phase, which is more concentrated in REEs, can be filtered off as a fairly concentrated REE solid mass and the liquor can be recycled back to recover more P nutrients. Alternatively, the REE enriched precipitate was dissolved completely in nitric acid and re-precipitated again by addition of ammonium hydroxide to pH 1.2. A chemical equilibrium software, MEDUSA (Puigdomenech, 2013) has been used to evaluate the experimental results and to estimate the optimum conditions for selectively dissolving the precipitate. 

  • 4.
    Annaduzzaman, Md.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Biswas, Ashis
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Hossain, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Ahmed, Kazi Matin
    University of Dhaka, Bangladesh.
    Tubewell platform color: A low-cost and rapid screening tool for arsenic and manganese in drinking water2013Conference paper (Other academic)
    Abstract [en]

    Presence of high level of geogenic arsenic (As) in groundwater is one of the major and adverse drinking water quality problem all over the world, especially in Southeast Asia, where groundwater is the prominent drinking water source. Bangladesh is already considered as one of the most As affected territories, where As contamination in the groundwater is key environmental disasters. Recently besides As, presence of high level of manganese (Mn) in drinking water has also got attention due to its neurological effect on children. It becomes very essential to formulate a reliable safe drinking water management policy to reduce the health threat caused by drinking As and Mn contained groundwater. The development of a simple low cost technique for the determination of As and Mn in drinking water wells is an important step to formulate this policy. The aim of this study was to evaluate the potentiality of tubewell platform color as low-cost, quick and convenient screening tool for As and Mn in drinking water wells (n=272) in a highly arsenic affected area on Matlab, Southeastern Bangladesh.

    The result shows strong correlation between the development of red color stain on tubewell platform and As enrichment in the corresponding tubewell water compared to WHO drinking water guideline (10 μg/L) as well as Bangladesh drinking water standard (BDWS) (50 μg/L), with certainty values of 98.7% and 98.3% respectively. The sensitivity and efficiency of red colored platforms to screen high As water in tubewells are 98% and 97% respectively at 10 μg/L, whereas at cut-off level of 50μg/L both sensitivity and efficiency values are 98%. This study suggests that red colored platform could be potentially used for primary identification of tubewells with elevated level of As and thus could prioritise sustainable As mitigation management in developing countries. Due to lack of tubewells with black colored platform in the study area, the use of platform color concept for screening of Mn enriched water in the wells have not been tested significantly, which requires further study.

    Acknowledgements: This study was carried out with support from the Liuuaeus-Palme Academic Exchange Programme supported by International Programs Office (IPK) and the KTH led joint collaborative action research project on Sustainable Arsenic Mitigation- SASMIT (Sid Contribution 750000854).

  • 5.
    Aullón Alcaine, Anna
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Schulz, C.
    Universidad Nacional de la Pampa, Argentina.
    Bundschuh, Jochen
    University of Southern Queensland, Australia.
    Thunvik, Roger
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Physics.
    Mörth, Carl-Magnus
    Stockholms Universitet, Institutionen för geologiska vetenskaper.
    Geogenic arsenic and fluoride in shallow aquifers of northeastern La Pampa, Argentina: mobility constraints2013Conference paper (Other academic)
    Abstract [en]

    High concentrations of geogenic arsenic (As) and fluoride (F-) in groundwater have been reported at elevated concentrations in different parts of the Chaco-Pampean Plain, in Argentina, where more than 2 million people may be exposed to high levels of these toxic elements through drinking water. Groundwater from the shallow aquifer is far exceeding the permissible WHO Standard limits of 10 μg/L for As and 1.5 mg/L for fluoride, as well as the Argentinean Standard limit of 50 μg/L for As. Geogenic As results due to the weathering of ash originated by volcanic eruptions from the Andean Cordillera and transported by wind and deposited along with the sediments and also as discrete layers and lenses over large geographical area containing around 90% of rhyolitic glass. Groundwater is hosted in a sandy silty interconnected system of aquifers and aquitards within the The Pampean aquifer. A total of 44 groundwater samples were collected from the shallow aquifers in NE of La Pampa province. Two rural areas covering an area of 600km2 in Quemú Quemú (QQ) and 300km2 in Intendente Alvear (IA) were investigated in the present study. Groundwater was circum-neutral to alkaline (pH 7.43-9.18), predominantly oxidizing (Eh ~0.24 V) with widely variable EC range (456-11,400 μS/cm). The major cation dissolved in groundwater was Na+, while the predominant anions were HCO3-, Cl- and SO42-, respectively. Water type in QQ was mostly Na-HCO3- while in IA, the composition differed between Na-HCO3- and Na-Cl-SO42- water types. Groundwater composition showed high degree of mineralization and high salinity evidenced by high EC. In discharge areas, high evaporation rates result in high salinity of shallow groundwater and visible salts incrustations on the surface of the lakes. Elevated concentrations of NO3- and PO43- observed in some wells indicated possible anthropogenic contamination. Total As concentration in groundwater from QQ ranged from 5.58 to 535 μg/L, where 94% of the wells exceeded the WHO standard limit for safe drinking water of 10 μg/L, and 56% of the wells exceeded the old Argentine standard limit of 50 μg/L. F- concentrations revealed heterogeneity and high concentrations in some wells (0.5-14.2 mg/L), 78% of samples in QQ study area exceeded the WHO standard limit of 1.5 mg/L. Under oxidizing conditions and neutral to alkaline pH, arsenate (AsV) species predominated, mainly in HAsO42- forms. As "hotspots" indicated locally contamination and correlated positively with F-, HCO3-, B and V and showed negative correlation with salinity, dissolved Fe, Al and Mn. The mechanisms involved in the mobilization of As in the shallow aquifers are controlled by the rise of pH, variations in Eh conditions and the presence of competitor ions (HCO3-, PO43-, Si, V oxyanions). Geochemical processes like adsorption/desorption, precipitation/dissolution and redox reactions may trigger to As mobilization in the shallow aquifers of La Pampa region.

  • 6.
    Bagherbandi, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Tenzer, Robert
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Moho depth uncertainties in the Vening-Meinesz Moritz inverse problem of isostasy2014In: Studia Geophysica et Geodaetica, ISSN 0039-3169, E-ISSN 1573-1626, Vol. 58, no 2, p. 227-248Article in journal (Refereed)
    Abstract [en]

    We formulate an error propagation model based on solving the Vening Meinesz-Moritz (VMM) inverse problem of isostasy. The system of observation equations in the VMM model defines the relation between the isostatic gravity data and the Moho depth by means of a second-order Fredholm integral equation of the first kind. The corresponding error model (derived in a spectral domain) functionally relates the Moho depth errors with the commission errors of used gravity and topographic/bathymetric models. The error model also incorporates the non-isostatic bias which describes the disagreement, mainly of systematic nature, between the isostatic and seismic models. The error analysis is conducted at the study area of the Tibetan Plateau and Himalayas with the world largest crustal thickness. The Moho depth uncertainties due to errors of the currently available global gravity and topographic models are estimated to be typically up to 1-2 km, provided that the GOCE gravity gradient observables improved the medium-wavelength gravity spectra. The errors due to disregarding sedimentary basins can locally exceed similar to 2 km. The largest errors (which cause a systematic bias between isostatic and seismic models) are attributed to unmodeled mantle heterogeneities (including the core-mantle boundary) and other geophysical processes. These errors are mostly less than 2 km under significant orogens (Himalayas, Ural), but can reach up to similar to 10 km under the oceanic crust.

  • 7.
    Bagherbandi, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics. University of Gävle, Sweden.
    Tenzer, Robert
    Sjöberg, Lars E.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Abrehdary, Majid
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    On the residual isostatic topography effect in the gravimetric Moho determination2015In: Journal of Geodynamics, ISSN 0264-3707, E-ISSN 1879-1670, Vol. 83, p. 28-36Article in journal (Refereed)
    Abstract [en]

    In classical isostatic models, a uniform crustal density is typically assumed, while disregarding the crustal density heterogeneities. This assumption, however, yields large errors in the Moho geometry determined from gravity data, because the actual topography is not fully isostatically compensated. Moreover, the sub-crustal density structures and additional geodynamic processes contribute to the overall isostatic balance. In this study we investigate the effects of unmodelled density structures and geodynamic processes on the gravity anomaly and the Moho geometry. For this purpose, we define the residual isostatic topography as the difference between actual topography and isostatic topography, which is computed based on utilizing the Vening Meinesz-Moritz isostatic theory. We show that the isostatic gravity bias due to disagreement between the actual and isostatically compensated topography varies between 382 and 596 mGal. This gravity bias corresponds to the Moho correction term of 16 to 25 km. Numerical results reveal that the application of this Moho correction to the gravimetrically determined Moho depths significantly improves the RMS fit of our result with some published global seismic and gravimetric Moho models. We also demonstrate that the isostatic equilibrium at long-to-medium wavelengths (up to degree of about 40) is mainly controlled by a variable Moho depth, while the topographic mass balance at a higher-frequency spectrum is mainly attained by a variable crustal density.

  • 8.
    Baken, Stijn
    et al.
    KU Leuven, Belgium.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Smolders, Erik
    KU Leuven, Belgium.
    The association between iron and carbon in freshwater colloids2013Conference paper (Refereed)
    Abstract [en]

    Iron and carbon are important constituents of natural colloids, which intimately links the fate of these two elements in riverine systems. Iron may strongly affect the binding of trace metals by organic matter, e.g. through competition for binding sites, which highlights the importance of a correct appreciation of the Fe speciation in surface waters. However, the chemistry of Fe and C in natural colloids is complex and depend on many factors including the pH, the Fe:C ratio, and the redox speciation of Fe [1-3]. Two areas with a contrasting Fe chemistry were studied: a lowland area with widespread seepage of iron-rich groundwater, and an upland peat area. Samples of ten oxic, well-mixed streams were subjected to cascade filtration using conventional filtration (1.2 µm, 0.45 µm, 0.1 µm) and cross-flow ultrafiltration (CFF; 5 kDa). The colloidal fraction, here operationally defined as between 0.45 µm and 5 kDa, was isolated by CFF and subsequently freeze-dried. The speciation of colloidal Fe was determined by EXAFS spectroscopy at the Fe K-edge (MAX-lab, Lund, Sweden). In the rivers draining upland peat, Fe and C were predominantly recovered in the fraction between 5 kDa and 0.1 µm. Conversely, in the rivers draining the lowland with extensive seepage of iron-rich groundwater, Fe was most abundant in the > 0.1 µm fraction, whereas C was predominantly present < 0.1 µm. The EXAFS data reveal that colloidal Fe speciation is different in both study areas. It exists as mononuclear Fe complexed by dissolved organic matter, as colloidal hydrous ferric oxides (likely stabilized by adsorbed organic matter), or as a mixture of these. The colloidal Fe concentrations show considerable seasonal variability. Overall, this study contributes to a better understanding of colloidal Fe speciation and of its interaction with organic C.

  • 9. Baken, Stijn
    et al.
    Sjöstedt, Carin
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Seuntjens, Piet
    Desmet, Nele
    De Schutter, Jan
    Smolders, Erik
    Characterisation of hydrous ferric oxides derived from iron-rich groundwaters and their contribution to the suspended sediment of streams2013In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 39, p. 59-68Article in journal (Refereed)
    Abstract [en]

    When Fe(II) bearing groundwaters surface in streams, particulate authigenic Fe-rich material is produced by oxidation. Such freshly precipitated Fe minerals may be transported as suspended sediment and have a profound impact on the fate of trace metals and nutrients in rivers. The objective of this study was to monitor changes in mineralogy and composition of authigenic material from its source to streams of increasing order. Groundwaters, surface waters, and suspended sediment in streams of different order were sampled in the Kleine Nete catchment (Belgium), a lowland with Fe-rich groundwaters (3.5-53.8 mg Fe/L; pH 6.3-6.9). Fresh authigenic material (>0.45 mu m) was produced by oxidising filtered (<0.45 mu m) groundwater and surface water. This material contained, on average, 44% Fe, and smaller concentrations of C, P, and Ca. Iron EXAFS (Extended X-ray Absorption Fine Structure) spectroscopy showed that the Fe was present as poorly crystalline hydrous ferric oxides with a structure similar to that of ferrihydrite. The Fe concentration in the suspended sediment samples decreased to 36-40% (stream order 2), and further to 18-26% (stream order 4 and 5). Conversely, the concentrations of organic C, Ca, Si, and trace metals increased with increasing stream order, suggesting mixing of authigenic material with suspended sediment from a different source. The Fe speciation in the suspended sediment was similar to that in fresh authigenic material, but more Fe-Fe interactions were observed, i.e. it was increasingly hydrolysed, suggesting ageing reactions. The suspended sediment in the streams of order 4 and 5 is estimated to contain between 31% and 59% of authigenic material, but more data are needed to refine this estimate. The authigenic material is an important sink for P in these streams which may alleviate the eutrophication risk in this catchment.

  • 10.
    Berggren Kleja, Dan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Elert, Mark
    Kemakta Konsult AB.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jarvis, las
    Markvetenskap, SLU.
    Norrström, Ann-Catrine
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Metallers mobilitet i mark2006Report (Refereed)
    Abstract [sv]

    I rapporten beskrivs nuvarande kunskapsläge när det gäller metallers uppträdande imark. Riskbedömningar för metaller i förorenad mark diskuteras.De flesta metaller binds i viss utsträckning i marken, oftast genom olika ytreaktioner med markens organiska material eller med järn- och aluminiumoxider, ochibland även genom utfällningsreaktioner. I vilken omfattning detta sker beror avfaktorer som t.ex. pH, redoxförhållanden, löst organiskt material (DOC) i markvattnet, samt förekomst av konkurrerande joner. Det är också viktigt att beaktavilka former metallerna förekommer som i markvattnet. Komplexbildning medt.ex. DOC minskar i regel toxiciteten. För att bättre ta hänsyn till markkemiskaförhållanden i riskbedömningen bör geokemiska modeller komma till ökad användning.Metaller lösta i vattnet följer med när vattnet strömmar och kan transporterastill grund- och ytvatten eller tas upp av växter. Hur snabbt detta går beror, förutomkemiska och biologiska processer, även på en rad olika jordegenskaper. Till exempel innehåller vissa jordar s.k. makroporer vilka ger upphov till preferentiellt flöde.Detta innebär att en del av metallerna snabbare kan transporteras genom marken,förbi jordpartiklar där metallerna annars skulle bindas.De olika modeller som används för att beskriva påverkan av markförorening pågrundvatten kan delas in i två grupper: stationära modeller antar att källtermen ärkonstant och tar enbart hänsyn till den utspädning som sker i grundvattnet. Exempel på sådana modeller är den svenska riktvärdesmodellen, JAGG och RBCA. I detvå senare modellerna finns möjlighet att ta hänsyn till nedbrytning av organiskaämnen. Tidsberoende modeller antar en avklingande källterm och en tidsberoendetransport i grundvattnet, exempelvis RISC och TAC-modellen. För beräkning avtransport i grundvattnet tas hänsyn till flödes- och fastläggningsmekanismer somadvektion, dispersion och linjär sorption.Med hjälp av laktester kan man uppskatta den andel av metallföroreningen somär löslig i vatten. Denna information kan sedan användas för att beräkna adsorptionsparametrar (Kd-värden, m.m.) för spridningsmodeller. Laktester kan ibland gemissvisande resultat eftersom de orsakar utspädning av provet, bl.a. blir DOCkoncentrationerna alltför låga. Dessutom bör de inte användas för sulfidjordar.Geokemiska modeller kan användas för att förbättra tolkningen av laktester för attfå till stånd realistiska uppskattningar av Kd-värden.Det finns ett antal spridningsmodeller som kan användas för att bedöma riskenför spridning till grundvatten och ytvatten. De är kraftfulla verktyg som dock ännuinte använts i någon större utsträckning i Sverige. Detta beror på flera orsaker, bl.a.de hydrogeologiska förhållandena i Sverige, behovet av anpassningen av de modeller som är allmänt tillgängliga, svårigheter att ta fram bra dataunderlag samt ensvag tradition i att använda modeller och förstå modellresultat.Ett par angelägna forsknings- och utvecklingsinsatser är att ta fram bättre uppskattningar av metalladsorption i svensk mark, och att anpassa existerande spridningsmodeller för användning i riskbedömningar.

  • 11.
    Biswas, Ashis
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Neidhardt, H.
    Karlsruhe Institute of Technology, Germany.
    Halder, Dipti
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Kundu, A.K.
    University of Kalyani, India.
    Chatterjee, Debashis
    University of Kalyani, India.
    Berner, Z.
    Karlsruhe Institute of Technology, Germany.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Surface complexation modeling of temporal variability of arsenic in groundwater: Estimating the role of competing ions in the mobilization processes2013Conference paper (Refereed)
    Abstract [en]

    This study investigates the relative roles of different competing ions on the mobilization of arsenic (As) by surface complexation modeling of As rich groundwater in the aquifer of Bengal Basin. Two sets of piezometers, installed at different depths of the shallow aquifer (<50 m), have been monitored for As and other relevant hydrogeochemical parameters over a period of 20 months. The potentiality of two different surface complexation models (SCM), developed for ferrihydrite and goethite has been explored to account for the observed temporal variation in As(III) and As(V) concentration in groundwater. The SCM for ferrihydrite appears as the better predictor for the observed variation in both As(III) and As(V) concentration. It is estimated that among the competing ions PO43- is the major competitor of As(III) and As(V) adsorption into Fe oxyhydroxide and competing ability of the ions decreases as PO43- >> Fe(II) > H4SiO4 = HCO3-. The result of sensitivity test indicates that the competition of PO43- with As for the adsorption sites might already reach nearly to the stage of maxima. It is also shown that a slight increase or decrease in pH can have overwhelming effect on the mobility of As(III) and As(V) by changing their concentration oppositely. It appears that only the reductive dissolution of Fe oxyhydroxide cannot explain the observed high As concentration in the groundwater of Bengal Basin. In absence of potential competition for the adsorption sites, As released due to reductive dissolution of Fe oxyhydroxide would have been re-adsorbed into the residual Fe phases. This study suggests that the reductive dissolution of Fe oxyhydroxide followed by competitive ion exchange with the aquifer sediment is the processes conducive for As enrichment in groundwater of the sedimentary aquifers.

  • 12.
    Biswas, Ashis
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. University of Kalyani.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. Swedish University of Agricultural Sciences.
    Neidhardt, Harald
    Karlsruhe Institute of Technology, Germany.
    Halder, Dipti
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. University of Kalyani.
    Kundu, Amit Kumar
    University of Kalyani, India.
    Chatterjee, Debashis
    University of Kalyani, India.
    Berner, Zsolt
    Karlsruhe Institute of Technology, Germany.
    Bhattacharya, Prosun
    University of Kalyani.
    Estimating the role of competing ions on the arsenic mobilization processes in the aquifers of Bengal Basin by surface complexation modeling2013Conference paper (Refereed)
    Abstract [en]

    This study investigates the relative roles of the different competing ions on the arsenic (As) mobilization in the sedimentary aquifers of Bengal basin by surface complexation modeling of the temporal varaibility of As in shallow (<50 m) groundwater. Two sets of piezometers (2×5 = 10), installed at the two sites with relatively contrasting dissolved As concentration in groundwater, were monitored bi-weekly for As and other hydrogeochemical parameters over a period of 20 months. The estimation of the standard deviation (SD) for As(III) reflects strong temporal variation (SD ≥10 μg/L) in all the piezometers of two sites over the monitoring period. Particularly, the variation is more prominent in the shallowest part of the aquifer, where the site specific cyclic trends are evident. While, As(V) shows significant temporal variation in the piezometers of high As site only and no specific trend is reflected in the variation.

    Two different surface complexation models (SCMs), developed for ferrihydrite and goethite have been explored to account for the observed temporal variation in As(III) and As(V) concentrations. The SCM for ferrihydrite has provided the better estimation for both As(III) and As(V) variations.

    Among the different competing ions, PO43- appears as the major competitor of As(III) and As(V) adsorption onto ferrihydrite and the competition ability decreases in the order PO43- >> Fe(II) > H4SiO4 = HCO3-. It is further revealed that a small decrease in pH significantly increases the concentration of As(III) and decreases the As(V) concentration and vice versa. The present study suggests that the reductive dissolution of Fe oxyhydroxides alone cannot explain the observed high As concentration in groundwater of the sedimentary aquifers. Perhaps, the reductive dissolution of Fe oxyhydroxides followed by competitive sorption reactions with the aquifer sediment is the processes conducive for As enrichment in the groundwater of Bengal basin.

  • 13.
    Biswas, Ashis
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. University of Kalyani, India .
    Neidhardt, Harald
    Kundu, Amit K.
    Halder, Dipti
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering. University of Kalyani, India .
    Chatterjee, Debashis
    Berner, Zsolt
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Spatial, vertical and temporal variation of arsenic in shallow aquifers of the Bengal Basin: Controlling geochemical processes2014In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 387, p. 157-169Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the geochemical processes that regulate the spatial, temporal and vertical variation of dissolved arsenic (As) in shallow aquifers (<50 m) is a prerequisite for sustainable drinking water management in the Bengal Basin. The present study conducted at Chakdaha Block of the Nadia District, West Bengal, India, combined a high resolution hydrogeochemical monitoring study over 20 months from two sets of piezometers (2 x 5) to the sediment geochemistry at areas with high (average:146 mu g/L, n = 5) and relatively low (average: 53.3 mu g/L, n = 10) dissolved As concentrations in groundwater. The determination of the isotopic composition of delta H-2 and delta O-18 in groundwater of the two sites indicated the recharge of evaporative surface water to the aquifer. The concentrations of major aqueous solutes (Ca2+, Mg2+, Na+, K+, HCO3- and Cl-) and electrical conductivity were considerably higher in wells at the high As site compared to the low As site. Additionally, at the high As site, the major ions, Fe, SO42-, electrical conductivity, delta H-2 and delta O-18 showed markedly greater enrichment in the shallowest part (<24 m) of the aquifer compared to the deeper part, reflecting vertical layering of groundwater composition within the aquifer. The oxidation of pyrites has been attributed to the high rate of mineral dissolution resulting in such greater enrichments in this part of the aquifer. In addition, the anthropogenic input with recharge water possibly increased the concentrations of Cl- in this part of the aquifer. The vertical layering of groundwater was absent in the aquifer at the low As site. The absence of such layering and relatively low major ion concentrations and electrical conductivity could be linked to the enhanced aquifer flushing and decreased water-ediment interactions influenced by local-scale groundwater abstraction. The seasonal variations of As concentrations in groundwater were observed only in the shallowest part of the aquifers (<30 m). Furthermore, the As concentrations in groundwater at the uppermost part of the shallow aquifers (<21 m) increased continuously over the monitoring period at both sites. This study supports the view that the reductive dissolution of Fe oxyhydroxides coupled with competitive PO43- sorption reactions in the aquifer sediment enriches As in groundwater of the Bengal Basin. However, the additional Fe released by the weathering of silicate minerals, especially biotite, or the precipitation of Fe as secondary mineral phases such as siderite, vivianite and acid volatile sulfides may result in the decoupling of As and Fe enrichment in groundwater. The redox zonation within the aquifer possibly regulates the vertical distribution of As in the groundwater.

  • 14.
    Björnbom, Pehr
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Temperature lapse rates at restricted thermodynamic equilibrium in the Earth system2015In: Dynamics of atmospheres and oceans (Print), ISSN 0377-0265, E-ISSN 1872-6879, Vol. 69, p. 26-36Article in journal (Refereed)
    Abstract [en]

    Equilibrium temperature profiles obtained by maximizing the entropy of a column of fluid with a given height and-volume under the influence of gravity are discussed by using numerical experiments. Calculations are made both for the case of an ideal gas and for a liquid with constant isobaric heat capacity, constant compressibility and constant thermal expansion coefficient representing idealized conditions corresponding to atmosphere and ocean. Calculations confirm the classical equilibrium condition by Gibbs that an isothermal temperature profile gives a maximum in entropy constrained by a constant mass and a constant sum of internal and potential energy. However, it was also found that an isentropic profile gives a maximum in entropy constrained by a constant mass and a constant internal energy of the fluid column. On the basis of this result a hypothesis is suggested that the adiabatic lapse rate represents a restricted or transitory and metastable equilibrium state, which has a maximum in entropy with lower value than the maximum in the state with an isothermal lapse rate. This transitory equilibrium state is maintained by passive forces, preventing or slowing down the transition of the system to the final or ultimate equilibrium state.

  • 15.
    Blomberg, Lars G.
    et al.
    KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Eriksson, Stefan
    KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Cumnock, Judy A.
    KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Yamauchi, M.
    Clemmons, J. H.
    Marklund, Göran T.
    KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Lindqvist, Per-Arne
    KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Karlsson, Tomas
    KTH, Superseded Departments, Alfvén Laboratory. KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Lundin, R.
    Solar windmagnetosphere-ionosphere coupling: an event study based on Freja data2004In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 66, no 5, p. 375-380Article in journal (Refereed)
    Abstract [en]

    Freja data are used to study the relative contributions from the high-latitude (reconnection/direct entry) and low-latitude (viscous interaction) dynamos to the cross-polar potential drop. Convection streamlines which are connected to the high-latitude dynamo may be identified from dispersed magnetosheath ions not only in the cusp/cleft region itself but also several degrees poleward of it. This fact, together with Freja's orbital geometry allows us to infer the potential drop from the high-latitude dynamo as well as to obtain a lower limit to the potential drop from the low-latitude dynamo for dayside Freja passes. All cases studied here are for active magnetospheric conditions. The Freja data suggest that under these conditions at least one third of the potential is generated in the low-latitude dynamo. These observations are consistent with earlier observations of the potential across the low-latitude boundary layer if we assume that the low-latitude dynamo region extends over several tens of Earth radii in the antisunward direction along the tail flanks, and that the majority of the potential drop derives from the sun-aligned component of the electric field rather than from its cross-boundary component, or equivalently, that the centre of the dynamo region is located quite far down tail. A possible dynamo geometry is illustrated.

  • 16.
    Borgström, Kristina
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Spridningsrisk för metaller till grundvatten från en vägslänt2007Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It is well known that the areas in the vicinity of roads are polluted due to traffic, mainly in form of heavy metals and

    PAHs (polycyclic aromatic hydrocarbons). The pollutions are transported to the surroundings by air, splash or

    highway runoff where they either infiltrate into the ground or flow on the surface to a surface water recipient. The

    Swedish National Road Administration has the responsibility for the national road networks impact on the environment.

    The water protection area of Östra Mälaren contains 230 kilometres governmental roads of which some are

    the most busy ones in Sweden (E4, E18 and E20). Due to this a cost effective way is needed to take care of the

    polluted highway runoff that may contaminate the water recipients in the surroundings. Soils have capabilities to

    retain pollutions which stop the further transport to the groundwater. This capacity of the soil differs between

    different sites since the soil material is very heterogonous. The soils texture decides to a large degree the concentration

    of the metal in the leachate. A large amount of clay and humic substances gives a high capacity to retain metal

    ions, whereas in a more sandy soil the leaching of pollutions is larger. To examine the risk of downward transport in

    a drain situated along a busy highway outside Stockholm, samples were taken and analyzed for the total content of

    Cd, Cr, Cu, Pb and Zn and the potential leachable amount. The gradients of the total content with depth and distance

    from the road showed that the drain was polluted and most obvious was this for Cu, Pb and Zn. Cadmium had

    the highest concentration in the bottom of the drain while the concentration in the slope (e.g. closer to the highway)

    were significantly lower. The Cr concentration was close to background values and showed no significant trend at all.

    The leaching tests showed that only small amounts of the total metal contents were leachable, 0,16 %, 2 % and 8,8 %

    for Pb, Cu and Zn. In spite of this the concentrations of Pb and Zn exceeded the drinking water criteria. This indicates

    that the groundwater in the area may have enhanced metal concentrations. Cu and Pb occurred in association

    with dissolved organic carbon (DOC). The amount of DOC will increase with increasing pH and accordingly the risk

    of leaching. Zinc showed high correlations with Mn which indicates that Zn is adsorbed to oxides. This will lead to

    that a higher loss of Zn is expected in an environment with low pH and reduced conditions. In this study Lake

    Bornsjön is the final recipient and the inflow to the lake is situated 5 kilometres from the studied drain and hence the

    impact of the polluted highway runoff will be insignificant due to dilution. Although, in other parts in the water

    protection area the situation might be different, as well as in the future and this can lead to a change in the pollution

    load on the water reservoir.

  • 17. Bruggeman, C.
    et al.
    Maes, N.
    Christiansen, B. C.
    Stipp, S. L. S.
    Breynaert, E.
    Maes, A.
    Regenspurg, Simona
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Malmström, Maria E.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Liu, X.
    Grambow, B.
    Schaefer, Th
    Redox-active phases and radionuclide equilibrium valence state in subsurface environments - New insights from 6th EC FP IP FUNMIG2012In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 27, no 2, p. 404-413Article in journal (Refereed)
    Abstract [en]

    Within the 6th EC FP Integrated Project "Fundamental Processes of Radionuclide Migration'' (FUNMIG), progress has been made to improve knowledge about the phases and reaction mechanisms involved in complex reduction processes of radionuclide contaminants in natural subsurface environments. This review paper gives an overview of the achievements made by the research groups involved in this project, and puts the scope and results of the studies in a more global context. Firstly, both thermodynamic and experimental evidence show that green rust is present and reactive in subsurface groundwater with a composition that spans the Fe(II)/Fe(III) redox boundary. Green rust has been shown to reduce Np(V), Se(VI) and Se(IV), but the pathways for the redox processes and the reaction products that result are complicated, and change as a function of the reaction parameters. Secondly, considerable evidence has emerged that Se(IV) is reduced on Fe(II)-bearing minerals which are ubiquitous in subsurface environments. The stable Se valence state in the presence of FeS(2) has been shown to be Se(0). Also, natural dissolved humic substances that contain sufficient electron donating capacity are capable of interacting with, and possibly reducing, Se(IV) to lower valence states. Thirdly, the influence of HCO(3)(-) and organic ligands on the uptake and reduction of U(VI) on Fe(II)-bearing minerals was investigated. While it appeared that HCO(3)(-) decreased the extent of U(VI) uptake by the reducing surface, the fraction of reduced U(IV) in the solid phase increased with increasing HCO(3)(-) concentration. In contrast with the observations for HCO(3)(-), organic ligands decreased both the extent of U uptake, as well as the fraction of U(IV) found in the solid phase. The studies performed within FUNMIG show that investigating reduction-oxidation mechanisms require (1) a detailed control over reaction conditions (anoxic atmosphere, purification of solid phases, initial radionuclide speciation), (2) a rigorous follow-up of reaction products (both solution chemistry and spectroscopic methods), and (3) the consideration of slow kinetics in the setting up of an experiment. These requirements make the study and assessment of redox processes one of the most demanding scientific challenges for geochemists who are asked to make predictions for radionuclide transport behaviour in the environment.

  • 18.
    Bundschuh, Jochen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Sracek, O.
    Hydrogeochemistry principles for geochemical modeling2011In: Geochemical Modeling of Groundwater, Vadose and Geothermal Systems, CRC Press , 2011, p. 3-26Chapter in book (Other academic)
    Abstract [en]

    A wide diversity of physical and chemical processes control the distribution of species in waters in the vadose zone above the water table, and in the saturated zone below. The mineralogical composition of rocks or sediments, chemical reactions between solid, aqueous and gas phases, and oxidation/reduction (redox) processes are principal factors that influence the chemical composition of vadose-zone, ground-and surface waters, and the concentrations and mobilities of individual species. 

  • 19. Chatterjee, D.
    et al.
    Biswas, A.
    Bhowmick, S.
    Halder, D.
    Hazra, R.
    Majumder, S.
    Mukherjee-Goswami, A.
    Saha, D.
    Nath, B.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Geochemistry of arsenic in Bengal Delta Plain (West Bengal, India)2010In: Arsenic in Geosphere and Human Diseases, As 2010 - 3rd International Congress: Arsenic in the Environment, 2010, p. 125-126Conference paper (Refereed)
  • 20.
    Deng, Juan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Ban, Yifang
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    Liu, Jinshuo
    Li, Li
    Niu, Xin
    Zou, Bin
    Hierarchical Segmentation of Multitemporal RADARSAT-2 SAR Data Using Stationary Wavelet Transform and Algebraic Multigrid Method2014In: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 52, no 7, p. 4353-4363Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to develop a new effective method for hierarchical segmentation of multitemporal ultrafine-beam synthetic aperture radar (SAR) data in urban areas. Multitemporal RADARSAT-2 ultrafine-beam high-resolution horizontal transmit and horizontal receive-Synthetic Aperture Radar (HH-SAR) images acquired in the rural-urban fringe of the Greater Toronto Area during the summer of 2008 are selected for this research. Stationary wavelet transform (SWT) and algebraic multigrid (AMG) method are proposed for segmentation of SAR data. SWT is applied for decomposition of multitemporal SAR images in image preprocessing. The hierarchical and matrix-based AMG method is applied for segmentation. A pyramid of fine-to-coarse grids is constructed by iteration of selecting representative pixels and calculating the interpolation matrix between a fine-level grid and a coarse-level grid. When the pyramid is completed, segments are determined by a top-down scanning based on the interpolation matrices. The AMG techniques provide a complete hierarchical segmentation of SAR data. The experimental results show that our method produces higher accuracy than eCognition.

  • 21.
    Dubois, Isabelle E.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Specific surface area of some minerals commonly found in granite2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The specific surface area, determined by the BET method, is a parameter often used to scale results of mineral studies of surface reactions in terms of rate and capacity to the field scale. Such extrapolations of results from small-scale laboratory experiments to the field-scale are important within many environmental applications. An example of this is for the prediction of radionuclide retention in the bedrock surrounding a deep repository for radioactive waste, following failure of the engineered barriers, where radionuclides may sorb onto minerals constituting the geological environment.

    As a first step, the approach used in this work is to study the relationship between specific surface area and the particle size (0.075-8 mm) and to approach the field scale via measurements on large, centimetre-sized pieces, for seven natural minerals commonly found in granite: apatite, biotite, chlorite, K-feldspar, hornblende, labradorite and magnetite. The underlying assumption is that sorption of radionuclides can be related to specific surface area of a particular mineral in a continuation of this project.The results show that the phyllosilicates biotite and chlorite have a specific surface area that is about 10 times larger than the other minerals. Over the range of particle size fractions studied, the specific surface area varies between 0.1 and 1.2 m2g-1 for biotite and chlorite. The other studied minerals have specific surface areas varying between 0.01 m2g-1 for the largest fraction and up to 0.06 - 0.12 m2g-1 for the smallest. Results show linear relationships between the specific surface area and the inverse of the particle size for all studied minerals for small particle sizes, as expected. For some minerals, however, the data seemingly can be divided in two linear trends, where a change in internal surface area, surface roughness and/or particle geometry as the particle size decreases may explain this behaviour.

    Interestingly, for larger particles, there is a deviation from the linearity observed for small particles. Tentatively, this behaviour is attributed to a disturbed zone, created by the mechanical treatment of the material during particle size reduction, extending throughout small particles, but not altering an undisturbed core of the larger particles. In agreement with this, measurements on large pieces show a surface area 5 to 150 times lower than expected from the linear trends observed for the crushed material, implying an overestimation of the surface area and possibly also of the sorption capacities of the rock material from simple extrapolations of experimental results employing finely crushed material to the field situation.

  • 22.
    Dubois, Isablle E.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630). Chalmers University of Technology, Gothenburg, Sweden.
    Holgersson, S.
    Allard, S.
    Malmström, Maria
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Correlation between particle size and surface area for chlorite and K-feldspar2010In: Water-Rock Interaction - Proceedings of the 13th International Conference on Water-Rock Interaction, WRI-13 / [ed] P. Birkle, I.S. Torres-Alvorado, 2010, p. 717-720Conference paper (Refereed)
    Abstract [en]

    The specific surface area as determined by BET analysis is often used for scaling mineral surface reaction capacities and rates between particles of different sizes as found in nature. Generally, an inverse proportionality between BET area and particle size is assumed, based on geometry. However, macroscopic laboratory studies of mineral surface reactions generally employ crushed material that may have been mechanically disturbed, potentially leading to an artificial increase in the specific surface area, and a change in the apparent surface reactivity. In this study, we determine the BET area for natural K-feldspar and chlorite samples from Sweden as function of particle size in a first step towards relating the surface reactivity for these minerals to grain size.

  • 23.
    Dubois, Isablle E.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Holgersson, S.
    Allard, S.
    Malmström, Maria
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology (moved 20130630).
    Dependency of BET surface area on particle siz for some granitic minerals2011In: Proc. radiochem. acta, Vol. 1, p. 75-82Article in journal (Refereed)
    Abstract [en]

    In order to assess the geochemical retention properties of rocks, which will be the final barrier for radionuclide transport to the biosphere in the case of a failed deep underground repository for spent nuclear fuel, radionuclide sorption experiments are usually made with crushed material. This raises the issue of extrapolating results obtained from laboratory experiments to the field scale. As sorption is generally related to the surface area of the geological material, it is then important to consider the dependency of the specific surface area on the particle size. In this work, BET surface area determinations of samples of different particle sizes are conducted on two minerals commonly found in granite: labradorite and magnetite. The results show a linearre lationship between BET surface area and the inverse of the particle size, up to a certain particle size. Furthermore, results also show that the specific surface area for intact, larger pieces is much smaller than the one predicted by a linear extrapolation of results on crushed material. Therefore, extrapolation of BET area for fine particles to the field situation will lead to an overestimation of the surface area and thereby also the radionuclide sorption, if sorption coefficients are extrapolated as well. Also of importance is that these results show that sorption experiments on crushed material may dominantly reflect properties of new surface, created during the mechanically treatment of the samples.

  • 24.
    Ellmann, Artu
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301).
    Two deterministic and three stochastic modifications of Stokes’s formula: A case study for the Baltic countries2005In: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 79, no 1-3, p. 11-23Article in journal (Refereed)
    Abstract [en]

    In regional gravimetric geoid determination, it is customary to use the modified Stokes formula that combines local terrestrial data with a global geopotential model. This study compares two deterministic and three stochastic modification methods for computing a regional geoid over the Baltic countries. The final selection of the best modification method is made by means of two accuracy estimates: the expected global mean square error of the geoid estimator, and the statistics of the post-fit residuals between the computed geoid models and precise GPS-levelling data. Numerical results show that the modification methods tested do not provide substantially different results, although the stochastic approaches appear formally better in the selected study area. The 2.8-5.3 cm (RMS) post-fit residuals to the GPS-levelling points indicate the suitability of the new geoid model for many practical applications. Moreover, the numerical comparisons reveal a one-dimensional offset between the regional vertical datum and the geoid models based upon the new GRACE-only geopotential model GGM01s. This gives an impression of a greater reliability of the new model compared to the earlier, EGM96-based and somewhat tilted regional geoid models for the same study area.

  • 25.
    Eshagh, Mehdi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geodesy and Geoinformatics.
    On the reliability and error calibration of some recent Earth's gravity models of GOCE with respect to EGM082013In: ACTA GEOD GEOPHYS, ISSN 2213-5812, Vol. 48, no 2, p. 199-208Article in journal (Refereed)
    Abstract [en]

    The Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission is dedicated to recover spherical harmonic coefficients of the Earth's gravity field to degree and order of about 250 using its satellite gradiometric data. Since these data are contaminated with coloured noise, therefore, their inversion will not be straightforward. Unsuccessful modelling of this noise will lead to biases in the harmonic coefficients presented in the Earth's gravity models (EGMs). In this study, five of the recent EGMs of GOCE such as two direct, two time-wise and one space-wise solution are used to degree and order 240 and their reliability is investigated with respect to EGM08 which is assumed as a reliable EGM. The detected unreliable coefficients and their errors are replaced by the corresponding ones from EGM08 as a combination strategy. A condition adjustment model is organised for each two corresponding coefficients of GOCE EGMs and EGM08; and errors of the GOCE EGMs are calibrated based on a scaling factor, obtained from a posteriori variance factor. When the factor is less than 2.5 it will be multiplied to the error otherwise the error of EGM08 coefficient will be considered as the calibrated one. At the end, a simple geoid estimator is presented which considers the EGMs and their errors and its outcomes are compared with the corresponding geoid heights derived from the Global Positioning System (GPS) and the levelling data (GPS/levelling data), over Fennoscandia. This comparison shows that some of the combined-calibrated GOCE EGMs are closer to the GPS/levelling data than the original ones.

  • 26.
    Eshagh, Mehdi
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301).
    Kiamehr, Ramin
    KTH, School of Architecture and the Built Environment (ABE), Transport and Economics (closed 20110301).
    A Strategy for Optimum Designing of the Geodetic Networks from the Cost, Reliability and Precision Views2007In: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 42, no 3, p. 297-308Article in journal (Refereed)
    Abstract [en]

    There are different criteria for designing a geodetic network in an optimal way. An optimum network can be regarded as a network having high precision, reliability and low cost. Accordingly, corresponding to these criteria different single-objective models can be defined. Each one can be subjected to two other criteria as constraints. Sometimes the constraints can be contradictory so that some of the constraints are violated. In this contribution, these models are mathematically reviewed. It is numerically shown how to prepare these mathematical models for optimization process through a simulated network. We found that the reliability model yields small position changes between those obtained using precision respectively. Elimination of some observations may happen using precision and cost model while the reliability model tries to save number of observations. In our numerical studies, no contradictions can be seen in reliability model and this model seems to be more suitable for designing of the geodetic and deformation networks.

  • 27.
    Eveborn, David
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology. KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. JTI - Swedish Institute of Agricultural and Environmental Engineering, Sweden .
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology. KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. Department of Soil and Environment, Swedish University of Agricultural Sciences, Sweden.
    Elmefors, Elin
    JTI,Swedish Institute of Agricultural and Environmental Engineering.
    Yu, Lin
    Center for Environmental and Climate Research (CEC), Lund University.
    Eriksson, Ann-Kristin
    Department of Soil and Environment, Swedish University of Agricultural Sciences.
    Ljung, Emelie
    JTI,Swedish Institute of Agricultural and Environmental Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Phosphorus in soil treatment systems: accumulation and mobility2014In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 64, p. 42-52Article in journal (Refereed)
    Abstract [en]

    In several western countries, septic tanks with subsequent soil treatment systems (STS) are a common treatment technique for domestic wastewater in rural areas. However the suitability of STS (especially relatively close to surface waters) can be questioned since the discharge of phosphorus (P) from such effluents is not well known. In this study, six STS in Sweden (11 to 28 years old) were investigated by means of batch and column experiments on samples taken from the unsaturated subsoil beneath the distribution pipes. At all sites the wastewater had clearly influenced the soil. This was observed through decreased pH, increased amounts of oxalate extractable metals and altered P sorption properties. The amount of accumulated P in the STS (defined as the amount of total P in the STS samples minus the amount of total P in unused soil samples) were found to be between 0.32 and 0.87 kg m-3, which in most cases was just a small fraction of the estimated P load (< 30%). Column studies revealed that remarkably high P concentrations (up to 6 mg L-1) were leached from the material when deionized water was applied. However, the response to deionized water varied between the sites. The affinity for P in the soils was well correlated to the amount of oxalate-extractable aluminium (as evidenced by a strong relationship between oxalate-extractable Al and oxalate-extractable P) and generally soils with high content of oxalate extractable Al was also less vulnerable to P leakage.

  • 28.
    Gustafsson, Jon Petter
    KTH, Superseded Departments, Land and Water Resources Engineering.
    Modelling molybdate and tungstate adsorption to ferrihydrite2003In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 200, no 02-jan, p. 105-115Article in journal (Refereed)
    Abstract [en]

    The environmental geochemistry of molybdenum and tungsten is not well known. To enable predictions of Mo and W concentrations in the presence of ferrihydrite (hydrous ferric oxide), batch equilibrations were made with MoO42-, WO42-, o-phosphate (PO43-) and freshly prepared ferrihydrite suspensions in 0.01 M NaNO3 in the pH range from 3 to 10 at 25°C. The results showed that WO42- is adsorbed more strongly than MoO42- , and that both ions are able to displace PO43- from adsorption sites at low pH. Two models, the Diffuse Layer Model (DLM) and the CD-MUSIC Model (CDM), were tested in an effort to describe the data. In both models, the adsorption of MoO42- and WO42- could be described with the use of two monodentate complexes. One of these was a fully protonated complex, equivalent to adsorbed molybdic or tungstic acid, which was required to fit the data at low pH. This was found to be the case also for a data set with goethite. In competitive systems with PO43- , the models did not always provide satisfactory predictions. It was suggested this may be partly due to the uncertainty in the PO43- complexation constants.

  • 29.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Soil chemical behaviour of cadmium pigments from paints2013Report (Other academic)
    Abstract [en]

    A review focusing on the thermodynamic stability and dissolution rates of Cd-containing sulphides and selenides from paints is presented. In the surface horizon of Swedish agricultural soils, cadmium sulphide, CdS(s), and cadmium selenide, CdSe(s), are shown to be thermodynamically unstable. The presence of electron acceptors such as oxygen gas and iron(III) will lead to gradual dissolution of these compounds. The dissolution rate of Cd-containing sulphides is dependent on the amount of crystalline zinc sulphide in contact with the cadmium, as zinc will be dissolved preferentially from a mixed cadmium zinc sulphide mineral. In the absence of crystalline zinc sulphide, Cd will be dissolved completely after 1-3 years. The presence of crystalline zinc sulphide can extend the life span of CdS to 1-2 decades; however, sewage sludge contains mostly amorphous ZnS that will dissolve more quickly. In conclusion, if a time frame of several decades is applied, it is very likely that Cd from Cd pigments has a similar solubility and bioavailability as an easily soluble Cd salt such as cadmium chloride.

  • 30.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Dässman, Ellinor
    Swedish University of Agricultural Sciences.
    Bäckström, Mattias
    Örebro University.
    Towards a consistent geochemical model for prediction of uranium(VI) removal from groundwater by ferrihydrite2009In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 24, no 3, p. 454-462Article in journal (Refereed)
    Abstract [en]

    Uranium(VI), which is often elevated in granitoidic groundwaters, is known to adsorb strongly to Fe (hydr)oxides under certain conditions. This process can be used in water treatment to remove U(VI). To develop a consistent geochemical model for U(VI) adsorption to ferrihydrite, batch experiments were performed and previous data sets reviewed to optimize a set of surface complexation constants using the 3-plane CD-MUSIC model. To consider the effect of dissolved organic matter (DOM) on U(VI) speciation, new parameters for the Stockholm Humic Model (SHM) were optimized using previously published data. The model, which was constrained from available X-ray absorption fine structure (EXAFS) spectroscopy evidence, fitted the data well when the surface sites were divided into low- and high-affinity binding sites. Application of the model concept to other published data sets revealed differences in the reactivity of different ferrihydrites towards U(VI). Use of the optimized SHM parameters for U(VI)-DOM complexation showed that this process is important for U(VI) speciation at low pH. However in neutral to alkaline waters with substantial carbonate present, Ca-U-CO3 complexes predominate. The calibrated geochemical model was used to simulate U(VI) adsorption to ferrihydrite for a hypothetical groundwater in the presence of several competitive ions. The results showed that U(VI) adsorption was strong between pH 5 and 8. Also near the calcite saturation limit, where U(VI) adsorption was weakest according to the model, the adsorption percentage was predicted to be >80%. Hence U(VI) adsorption to ferrihydrite-containing sorbents may be used as a method to bring down U(VI) concentrations to acceptable levels in groundwater.

  • 31.
    Gustafsson, Jon Petter
    et al.
    Swedish University of Agricultural Sciences, Uppsala.
    Oromieh, Aidin Geranmayeh
    Swedish University of Agricultural Sciences, Uppsala.
    Sjöstedt, Carin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Persson, Ingmar
    Sveriges Lantbruksuniversitet.
    Berggren Kleja, Dan
    Swedish Geotechnical Institute, Stockholm, Sweden.
    Chromium (III) and bismuth (III) complexation to organic matter: EXAFS Spectroscopy and equilibrium modeling2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, no 5, p. 1235-Article in journal (Refereed)
    Abstract [en]

    The complexation of chromium(III) and bismuth(III) to organic matter was investigated by batch equilibrations with Suwannee River Fulvic Acid (SRFA) and with mor layer material (Risbergshöjden Oe). In the SRFA systems, 3 mM chromium(III) solutions were equilibrated with 9 g L-1 SRFA and equilibrated at different pH values ranging from 2 to 6. Characterization of the reaction products was made at MAX-Lab, Lund, Sweden, using Cr K-edge EXAFS spectroscopy at 5 989 eV. The spectra were interpreted using both conventional data treatment using EXAFSPAK and with wavelet transform (WT) analysis. The results show that chromium(III) formed monomeric organic complexes with SRFA. There was no evidence of polymerization with the exception of the particulate phase at pH 6, which was attributed to a limited extent of Cr(OH)3 formation.

    The mor layer material was equilibrated with chromium(III) and bismuth(III) solutions as a function of pH, time and competing ions (iron(III), aluminium(III), copper(II)). Again Cr

    K-edge and Bi L3-edge EXAFS spectroscopy was used, at 5 989 and 13 419 eV. The experiments showed a predominance of monomeric organic complexes for chromium(III). The sorption of chromium(III) was pH-dependent and to some extent found to be influenced by competition from aluminium(III) and copper(II). Chromium(III) complexation was found to be very slow at pH < 4, and equilibration times of three months or longer were required to reach equilibrium under these conditions. Concerning bismuth(III), complexation was quicker and found to be very strong, with more than 94 % bound at pH 1.2 at a high bismuth(III) loading. EXAFS spectroscopy showed that two complexes were involved, one monomeric and one di- or trimeric, with the latter being predominant at higher pH values, although it was present already at pH 1.2. In the organic bismuth(III) complexes, the bismuth(III) octahedron was found to be strongly distorted, which implies strong binding to organic acid functional groups. The complexation of bismuth(III) remained essentially unchanged even in the presence of a potent competitor such as iron(III).

    The results from the spectroscopic investigation and from the quantitative solution data were used to calibrate new and improved complexation models for the Stockholm Humic (SHM) and the NICA-Donnan models. In the case of the Stockholm Humic Model, both complexes as found by EXAFS spectroscopy were considered explicitly; this ensured the model to predict minimum competition effects in agreement with the laboratory results.

  • 32.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Tiberg, Charlotta
    SLU.
    Fosfors betydelse för metallers mobilitet i mark2013Report (Other academic)
    Abstract [en]

    The aim with this project was to investigate the role of dissolved phosphate for the adsorption of lead(II), copper(II), cadmium(II) and uranium(VI) onto ferrihydrite and to soils. The methods involved batch studies, EXAFS spectroscopy, and equilibrium modelling. Phosphate was found to significantly enhance the adsorption of all investigated metals onto ferrihydrite. Results obtained so far show that the results are consistent with the formation of ternary surface complexes at low pH, but additional research is required to understand the processes in more detail. Similar enhancements were not observed in soil samples to which phosphate is added, and the reasons for this remain to be fully elucidated. In any case, this research shows that the presence of phosphate may restrict the mobility of many trace metals in environments that contain iron(III) (hydr)oxides.

  • 33.
    Gustafsson, Jon Petter
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Tiberg, Charlotta
    Molybdenum binding to soil constituents in acid soils: An XAS and modelling study2015In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 417, p. 279-288Article in journal (Refereed)
    Abstract [en]

    Despite its importance as a trace element, the binding mechanisms of molybdenum in soils are not well known. In this study, we studied the binding of molybdenum onto selected soil samples, and we used X-ray absorption spectroscopy (XAS) to characterize the coordination of molybdenum on three important environmental sorbents: ferrihydrite (Fh), amorphous aluminium hydroxide (Al(OH)(3)) and fulvic acid. The X-ray near-edge structure (XANES) data showed that the added molybdenum(VI) was not reduced, although for the organic samples the coordination shifted from tetrahedral to octahedral. The EXAFS (extended X-ray absorption fine structure) analysis showed that molybdenum(VI) on Fh and Al(OH)(3) was dominated by edge-sharing bidentate complexes with Mo center dot center dot center dot Fe and Mo center dot center dot center dot Al distances of 2.80 and 2.62 angstrom, respectively. For ferrihydrite, there was a minor contribution from a corner-sharing bidentate complex at 3.55 angstrom. Further, geochemical modelling suggested an additional role of an outer-sphere complex at high pH. A sample from a spodic Bs horizon had XANES and EXAFS features similar to those of Mo sorbed to Al(OH)(3), highlighting the importance of Al(OH)(3)-type sorbents in this soil. However, in the studied organic samples molybdenum(VI) was present in a distorted octahedral configuration as an organic complex. The results were used to improve molybdenum binding reaction equilibrium constants in the CD-MUSIC model for ferrihydrite and in the Stockholm Humic Model. Collectively the results show that acid soils may contain sorbents able to bind molybdenum efficiently, and thus prevent its leaching to waters.

  • 34.
    Halder, Dipti
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Biswas, Ashis
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Bhowmick, S.
    University of Kalyani, India.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Nriagu, Jerome O.
    University of Michigan, USA.
    Guha Mazumder, D.N.
    DNGM Research Foundation, India.
    Slejkovec, Z.
    Josef Stefan Institute, Ljubljana, Slovenia.
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Chatterjee, Debashis
    University of Kalyani, India.
    Assessment of arsenic exposure risk from drinking water and dietary component in West Bengal, India2013Conference paper (Refereed)
    Abstract [en]

    The current status of arsenic (As) exposure risk from drinking water and different dietary components in rural Bengal has been compared in the present study. This study shows that the consumption of rice is the major source of dietary intake of inorganic As among the population when they are drinking As safe water. Consumption of vegetables does not pose a significant health threat to the population independently; it nevertheless can increase the total daily intake of inorganic As (TDI-iAs). The results indicate that when people are drinking water with As concentration <10 μg L-1, in 35% of the cases the total daily intake of inorganic As (TDI-iAs) exceeds the previous provisional tolerable daily intake (PTDI) value of 2.1 μg day-1 kg-1 BW, recommended by World Health Organization (WHO). It should be mention here that the joint FAO/WHO expert committee on food additives (JECFA) has withdrawn the previous PTDI value in their 72nd meeting because PTDI value was in the lower range of bench mark dose level for 0.5% increased of lung cancer. However, Codex Committee on Contaminants in Foods (CCCF) has argued that TDI-iAs below BMDL0.5 does not indicates that there is no risk and this motivated us to compare TDI-iAs of the participants with the previous PTDI value of 2.1 μg day-1 kg-1 bw. At the As concentration level <10 μg L-1in drinking water, the consumption of rice is the major source of daily intake of inorganic As. When As concentration in drinking water exceeds 10 μg L-1, drinking water and rice consumption contributes almost equally (~40% from rice, ~50% from drinking water, and 10% from vegetables according to median DI-iAs) and TDI-iAs exceeds previous PTDI for all the participants. The relative contribution of daily intake of iAs from drinking water (DI-iAs-DW) largely predominates over daily intake of iAs from rice (DI-iAs-R) when As concentration in drinking water exceeds 50 μg L-1. This study implies that when consumption of rice contributes significantly to the TDI-iAs, supply of drinking water to the population considering national drinking water standard of India and Bangladesh as a safety measure for As might compound the As exposure largely by increasing TDI-iAs. Thus it can be concluded that any effort to mitigate the As poisoning of rural villagers in Bengal must look beyond the drinking water and consider all the routes of exposure.

  • 35. Hirsch, Michael
    et al.
    Semeter, Joshua
    Zettergren, Matthew
    Dahlgren, Hanna
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Goenka, Chhavi
    Akbari, Hassanali
    Reconstruction of Fine-Scale Auroral Dynamics2016In: IEEE Transactions on Geoscience and Remote Sensing, ISSN 0196-2892, E-ISSN 1558-0644, Vol. 54, no 5, p. 2780-2791Article in journal (Refereed)
    Abstract [en]

    We present a feasibility study for a high-frame-rate Short-baseline auroral tomographic imaging system useful for estimating parametric variations in the precipitating electron number flux spectrum of dynamic auroral events. Of particular interest are auroral substorms, which are characterized by spatial variations of order 100 m and temporal variations of order 10 ms. These scales are thought to be produced by dispersive Alfven waves in the near-Earth magnetosphere. The auroral tomography system characterized in this paper reconstructs the auroral volume emission rate, to estimate the characteristic energy and location in the direction perpendicular to the geomagnetic field of peak electron precipitation flux, using a distributed network of precisely synchronized ground-based cameras. As the observing baseline decreases, the tomographic inverse problem becomes highly ill-conditioned; as the sampling rate increases, the signal-to-noise ratio degrades and synchronization requirements become increasingly critical. Our approach to these challenges uses a physics-based auroral model to regularize the poorly observed vertical dimension. Specifically, the vertical dimension is expanded in a low-dimensional basis, consisting of eigenprofiles computed over the range of expected energies in the precipitating electron flux, while the horizontal dimension retains a standard orthogonal pixel basis. Simulation results show typical characteristic energy estimation error less than 30% for a 3-km baseline achievable within the confines of the Poker Flat Research Range, using GPS-synchronized electron-multiplying charge-coupled device cameras with broadband BG3 optical filters that pass prompt auroral emissions.

  • 36.
    Holm, Regina
    Institutionen för naturgeografi och kvartärgeologi, Stockholms universitet.
    EN STUDIE AV BASKATJONDEPOSITIONEN I VÄGARS SIDOOMRÅDEN - MED INRIKTNING MOT GRUNDVATTNETS KVALITET2004Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Att det är många olika faktorer som kan inverka på mängden baskatjoner som sprids i vägars sidoområden, samt på vilket avstånd från vägen de sprids, är i litteraturen känt genom forskning på vägsalts spridning från vägarna. Min studie skiljer sig från tidigare gjorda studier i baskatjoners spridning i vägars sidoområden bl a genom att den visar resultat från en mer högtrafikerad väg samt från en hel saltningssäsong. Resultaten i detta examensarbete kan därför inte jämföras helt med tidigare studier, men de kan till viss del förstärka tidigare studiers resultat och teorier.

    Att vägsalt och dess medförande effekter invid vägar kan inverka negativt på miljön invid vägar är i litteraturen känt då ett flertal studier har gjorts inom området. Grundvattnets hårdhet ökar pga de jonbytesprocesser som vägsaltet påverkar. Höga natriumhalter i grundvattnet kan ge negativa hälsoeffekter. Hårt grundvatten dvs med höga halter av kalcium- och magnesiumjoner ger inte, enligt litteraturen, negativa hälsoeffekter i sig utan tvärtom. Däremot kan det innebära utfällningar i ledningar och det innehåller även höga halter av kloridjoner som kan påskynda korrosion på ledningar vilket medför att metaller kan komma ut i dricksvattnet. Ett grundvatten, som pga vägsaltets (NaCl) inverkan på jonbytesprocesserna i marken blivit hårt, innehåller tidvis även höga halter av natriumjoner eftersom dessa är mobila och efter en tid når grundvattnet.

    Trafikintensiteten vid provtagningsplatsen (E4 vid Kista) för de analyserade depositions- och jordproven, är ca 90 000 fordon/dygn. I detta examensarbete har depositionsprover analyserats med avseende på baskatjoner samt pH-bestämts. Depositionsproven kommer från olika avstånd från vägen i två profiler, från ett sandområde respektive ett lerområde. Markprover har i detta arbete tagits i både sandprofilen och lerprofilen för pH-bestämning.

    Generellt minskade baskatjonhalterna kraftigt inom ett avstånd av 10 meter från vägen, dvs ca 70 % till > 95 % av den totala baskatjondepositionen återfanns inom 10 meter från vägen. Resultaten visade att den avtagande trenden inte var likvärdig för alla baskatjonerna.

    Natriumhalterna var högst i samtliga depositionsprov, därefter kom i ordning kalcium, kalium och magnesium. Depositionsproven från sandprofilen (ett skogsområde) hade generellt lägre värden för samtliga baskatjoner jämfört med lerprofilen.

    Vid en jämförelse med bakgrundsdepositionen av kalcium och magnesium i depositionsproven 2 meter från vägen var kalciumhalten 45 respektive 20 gånger högre i ler- respektive sandprofil, magnesiumhalten var 5 respektive 4 gånger högre. Natriumhalterna i depositionsproven 2 meter från vägen var 900 till 1 400 gånger högre i sand- respektive lerprofil i jämförelse med bakgrundsdepositionen. För kalium gäller 9 till 15 gånger högre värden i sand- respektive lerprofil. Jämförelserna med bakgrundsdepositionen är mycket ungefärlig, storleksordningen framkommer dock. I sandprofilen respektive lerprofilen 50 meter från vägen var natriumhalten 2 respektive 3 gånger högre, kaliumhalten 3 gånger högre respektive likvärdig (ett prov avvek). Magnesiumhalten och kalciumhalten var i båda profilerna 50 meter från vägen lägre eller likvärdig med bakgrundsvärdet.

    Med avståndet från vägen sjunker pH-värdena i depositionsproven. Detta kan enligt andra studier bero på mängden vittringspartiklar från vägen. Ökad halt baskatjoner, från vägens vittringsprodukter, ger ökat pH då vittringsytorna på produkterna binder vätejoner.

    6

    Lerprofilens pH-värden i jordprov och depositionsprov, mätperiod I, är relativt lika. Ler- och sandprofilens jordprov 2 meter från vägen är likvärdiga (pH ca 7,6), sandprofilens pH-värde avtar sedan markant. Vid 10 meter från vägen har sandprofilen pH-värde ca 3,6 och lerprofilen 7,33, vid 50 meter från vägen är värdena ca 3,6 respektive 5,7. Enligt litteraturen påverkar rotsystem och humussyror pH-värdena, eventuellt kan detta vara fallet i sandprofilen. Hur mycket ett grundvatten nära en väg påverkas av vägsaltet, när det väl har infiltrerats i marken, vad gäller vattnets hårdhet är bl a beroende av hur stora spädningseffekterna är och katjonbyteskapaciteten (CEC) i marken. CEC är sannolikt beroende av flera faktorer t ex, vilken typ av lerpartiklar som finns i marken, om de är pH-beroende eller inte, samt hur stor mängd natriumjoner som finns i marken.

  • 37. Hoppe, Sabina
    et al.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Borg, Hans
    Breitholtz, Magnus
    Can natural levels of Al influence Cu speciation and toxicity to Daphnia magna in a Swedish soft water lake?2015In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 138, p. 205-210Article in journal (Refereed)
    Abstract [en]

    It is well known that chemical parameters, such as natural organic matter (NOM), cation content and pH may influence speciation and toxicity of metals in freshwaters. Advanced bioavailability models, e.g. Biotic Ligand Models (BLMs), can use these and other chemical parameters to calculate site specific recommendations for metals in the aquatic environment. However, since Al is not an input parameter in the BLM v.2.2.3, used in this study, there could be a discrepancy between calculated and measured results in Al rich waters. The aim of this study was to evaluate if the presence of Al in a circumneutral (pH 6) soft humic freshwater, Lake St. Envättern, will affect the Cu speciation and thereby the toxicity to the cladoceran Daphnia magna. The results show a statistically significant increase in the free Cu2+ concentration with Al additions and that measured levels of Cu2+ significantly differed from BLM calculated levels of Cu2+. Furthermore, there was also a statistically significant elevated acute toxic response to D. magna at low additions of Al (10μg/L). However, since the large difference between calculated and measured Cu2+ resulted in a significant but minor (factor of 2.3) difference between calculated and measured toxicity, further studies should be conducted in Al rich soft waters to evaluate the importance of adding Al as an input parameter into the BLM software.

  • 38.
    Hossain, Mohammad
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Rahman, M.
    NGO Forum for Public Health, Dhaka, Bangladesh.
    Ahmed, Kazi Matin
    University of Dhaka, Bangladesh.
    von Brömssen, Mattias
    Ramböll Sweden AB.
    Uddin, M.R.
    NGO Forum for Public Health, Dhaka, Bangladesh.
    Alam, M.J.
    University of Dhaka, Bangladesh.
    Haque, M.A.
    NGO Forum for Public Health, Dhaka, Bangladesh.
    Alam, M.S.
    NGO Forum for Public Health, Dhaka, Bangladesh.
    Rahman, M.M.
    University of Dhaka, Bangladesh.
    Sarwar, S.G.
    NGO Forum for Public Health, Dhaka, Bangladesh.
    Kibria, M.G.
    NGO Forum for Public Health, Dhaka, Bangladesh.
    Hasan, R.
    NGO Forum for Public Health, Dhaka, Bangladesh.
    Rashid, Nazhat Shirin
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Strategic approach for up-scaling safe water access considering hydrogeological suitability and social mapping in Matlab, southeastern Bangladesh2013Conference paper (Refereed)
    Abstract [en]

    In recent years, there has been a significant progress in understanding the source and mobilization process, sediment-water interactions, and distributions of arsenic in groundwater environment in Bangladesh. However, the impacts of arsenic mitigation are still very limited. A social survey conducted during 2009-2011 in 96 villages in Matlab revealed that only 18% of total tubewells provide As-safe water. The safe water access also varied between 0 and 90 percent in the region due to lack of knowledge about the local geology and unplanned tubewell development. SASMIT, an initiative of KTH-International Groundwater Arsenic Research Group has developed a method for safe tubewell installation considering hydrogeological suitability, safe water access and other relevant social and demographic information into account.

    Piezometers installed at 15 locations over an area of 410 km2, using local boring techniques allowed to delineate the hydrostratigraphy, characterize the aquifers in terms of sediment characteristics, water chemistry and hydraulic head distribution, which ultimately led to the identification of the suitable aquifers for tapping safe water. The piezometer locations with safe drinking water quality were then targeted for safe well installation based on the determination of safe buffer distances in a cluster of a few villages (mouzas). Social mapping of all the villages within the mauzas were done using GIS to evaluate the availability of safe water options for a cluster of households (bari). For safe well installations, priority was given to regions with safe water access, greater number of beneficiaries especially in poor households, and easy access to the site from a cluster of households. Through this approach, it was thus possible to make 95% of the newly installed wells As-safe thus scaled up the safe water access upto 40% in some mauzas. Thus the as a strategy to improve safe water access, the SASMIT study recommends investigating the hydrogeological suitability through installation of few piezometers with a minimum effort and based on the results the implementation plan can be made using GIS based social mappings for relatively uniform distribution and to maximize the safe water access.

  • 39. Jacks, G.
    et al.
    Harikumar, P. S.
    CWRDM, Kozhikode 673571, Kerala, India..
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Fluoride mobilisation in India2009In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 73, no 13, p. A578-A578Article in journal (Other academic)
  • 40.
    Jacks, Gunnar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Slejkovec, Zdenka
    Mörth, Magnus
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Redox-cycling of arsenic along the water pathways in sulfidic metasediment areas in northern Sweden2013In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 35, p. 35-43Article in journal (Refereed)
    Abstract [en]

    Arsenic has emerged as a problem element in groundwater. The most common mechanism of mobilising As from the solid phase into water is through the reductive dissolution of ferric oxyhydroxides. This investigation was made in northern Sweden where metasediments containing pyrite, pyrrhotite and arsenopyrite underlay about 4000 km(2). The overlying till contains as much as up to 100 mg kg (1) As. Speciation of the dissolved As shows that arsenite dominates largely over arsenate. The Fe oxyhydroxides formed may contain up to 0.5% As. Sandy sediments may contain 100-500 mg kg (1). Arsenic and Fe are closely correlated. The cycling of As in water, flora and fauna in wetlands has been studied. Ferric reduction occurs in wetlands and groundwater rich in Fe, and As is found to be discharging into ditches, brooks and streams. Wetland trees and plants show a moderately elevated content of As with a few species showing above 2 mg kg (1), the permissible level in fodder for domestic animals. The only plants having a high content of As are Equisetum species showing up to 26 mg kg (1). These plants make up a small fraction of the food of wild, grazing and browsing animals, for example moose and reindeer, and does not seem to constitute an environmental risk. However, the animals could be exposed to considerable amounts of As by drinking water from springs in wetlands. In the fauna, an elevated As content has so far been found in a limited number of benthic macroinvertebrate samples (1.23-42.1 mg kg (1) dry weight), in which inorganic As species (arsenate) predominate in the extractable fraction (62-82%) with lower amounts of arsenite, mono-and dimethylarsenic acid. Some samples also contained arsenobetaine, trimethylarsine oxide and tetramethylarsonium ion. To the authors' knowledge, this is the first report on As speciation in benthic macroinvertebrates. Fish species from polluted streams (pike and brown trout) had normal As levels (0.57-1.84 mg kg (1) dry weight), mainly present in a form of arsenobetaine (brown trout) or arsenobetaine and dimethylarsinic acid (pike). As both fish species also contained minor amounts of arsenite and arsenate, it is estimated that there is no serious health risk to potential consumers.

  • 41.
    Jakariya, M.
    et al.
    NGO Forum Drinking Water Supply & Sanitat, Dhaka 1207, Bangladesh..
    Rahman, S. N.
    NGO Forum Drinking Water Supply & Sanitat, Dhaka 1207, Bangladesh..
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Rahman, M.
    ICDDR B Ctr, Dhaka, Bangladesh..
    von Bromssen, M.
    KTH, School of Architecture and the Built Environment (ABE).
    Persson, L. -A
    Uppsala Univ, IMCH, Uppsala, Sweden..
    Vahter, M.
    Karolinska Inst, Inst Environm Med, S-10401 Stockholm, Sweden..
    Temporal and seasonal variation in tubewell water arsenic concentrations in Matlab, Bangladesh2009In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 73, no 13, p. A583-A583Article in journal (Other academic)
  • 42.
    Kasedde, Hillary
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy. Makerere University.
    Kirabira, John Baptist
    Makerere University.
    Bäbler, Mätthäus
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Energy Processes.
    Tilliander, Anders
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Characterization of brines and evaporites of Lake Katwe, Uganda2014In: Journal of African Earth Sciences, ISSN 0899-5362, Vol. 91, p. 55-65Article in journal (Refereed)
    Abstract [en]

    Lake Katwe brines and evaporites were investigated to determine their chemical, mineralogical and morphological composition. 30 brine samples and 3 solid salt samples (evaporites) were collected from different locations of the lake deposit. Several analytical techniques were used to determine the chemical composition of the samples including Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), Inductively Coupled Plasma-Sector Field Mass Spectrometry (ICP-SFMS), ion chromatography, and potentiometric titration. The mineralogical composition and morphology of the evaporites was determined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Physical parameters of the lake brines such as density, electrical conductivity, pH, and salinity were also studied. The results show that the lake brines are highly alkaline and rich in Na+, Cl-, CO32-, SO42-, and HCO3- with lesser amounts of K+, Mg2+, Ca2+, Br-, and F- ions. The brines show an intermediate transition between Na-Cl and Na-HCO3 water types. Among the trace metals, the lake brines were found to be enriched in B, I, Sr, Fe, Mo, Ba, and Mn. The solid salts are composed of halite mixed with other salts such as hanksite, burkeite and trona. It was also observed that the composition of the salts varies considerably even within the same grades.

  • 43. Khai, Nguyen Manh
    et al.
    Oborn, Ingrid
    Hillier, Steve
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.
    Modeling of metal binding in tropical Fluvisols and Acrisols treated with biosolids and wastewater2008In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 70, no 8, p. 1338-1346Article in journal (Refereed)
    Abstract [en]

    There is growing concern about the accumulation of metals in tropical agricultural soils. In this study, experimental results from batch studies were used to test whether multi-surface geochemical models could describe metal binding in selected Vietnamese soils. The multi-surface models considered metal binding to iron hydroxides (using the diffuse layer model), organic matter (Stockholm Humic model and NICA-Donnan model), and phyllosilicate clay (Gaines-Thomas equation) as well as complexation to dissolved organic and inorganic ligands in the solution phase. We found that for total dissolved Cd, Cu and Zn the two multi-surface models being tested provided very good model fits for all soils, as evidenced by low root-mean square errors between model predictions and observations. These results suggest that organic matter is an important sorbent for many metals in these soils. However, poor fits were obtained for Cr(III), Mn and Pb for all soils. The study also suggests that the pH is the main factor that controls the solubility of metals in tropical Fluvisols and Acrisols subjected to application of biosolids and wastewater, and that advanced multi-surface models can be used to simulate the binding and release of many trace metals.

  • 44.
    Kibria, M.G.
    et al.
    Kansas State University, USA.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Hossain, Mohammad
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Ahmed, Kazi Matin
    University of Dhaka, Bangladesh.
    Datta, Saugata
    Kansas State University.
    Arsenic mitigation by developing a tool based on gray and brown sediment solid phase characterization2013Conference paper (Refereed)
    Abstract [en]

    Arsenic (As) poses the greatest hazard towards drinking water quality in Bangladesh. Tubewell drinking water is one of the main sources for household based water options in rural Bangladesh. Our study area is in Matlab Upazila, in Bangladesh. The local drillers in this area are the only ones who have been utilized by the community to identify safe aquifer depths. The overall objective of this and the SASMIT project is to develop a community based initiative for sustainable As mitigation by developing a sediment color based tool for the local drillers prioritizing on the hydrogeological and geochemical investigations as to (a) why red/brown to off-white sediments produces As-safe water but contains high Mn; (b) as to why light gray sediment produce low As and Mn free water; and (c) why dark gray sediments produce high As bearing water. Shallow tubewells excepting those installed within off-white sediments are mostly contaminated with high As. High Mn in many wells is also an additional problem in some shallow aquifer depths. In our field studies we find the wells installed within light grey medium sand the As concentration was found below 50μg/L and Mn is within WHO guideline value of 0.4 mg/L.

    This study focuses on the adsorption behavior of oxidized reddish-red-brown sediments from Matlab region, and their capacity to attenuate As. Sediment extractions indicate a relatively low amount of As in the oxidized sediments. Reductive dissolution of Fe(III)-oxyhydroxides and release of its adsorbed As is considered to be the principal mechanism responsible for mobilization of As. Groundwater abstracted from oxidized reddish sediments, in contrast to reducing grayish sediments, contains significantly lower amount of dissolved As and can be a source of safe water. This study describes the lithofacies, mineralogy and results of adsorption experiments on the sediments within ~85m depth and establishes a relationship between aqueous and solid phase geochemistry along these intermediate depths of the aquifer.

    Core samples have been analyzed by petrographic microscopy, microtopography and distribution of elements within sediment grains by FESEM-EDX and clay and bulk mineralogy by XRD. Synchrotron aided μXANES and μXRD studies conducted for solid state As speciation (As3+ and As5+) in different depth core samples. The projected outcome is to incorporate detailed sediment characteristics of the different aquifers including all possible color variations available in the exploited intermediate depths within Matlab. This study would have a wider implication towards a broader scale regional remediation project that incorporates the enquiry of efficiency of sediment color as a simple and easy tool for identifying safe aquifers in major As risk prone areas. Knowing sediments more accurately would also enrich and strengthen the field based tools for identifying As-safe and As-Mn safe aquifers for tubewell installation.

  • 45.
    Kleja, Dan Berggren
    et al.
    SGI.
    Shibutani, Satomi
    Sveriges Lantbruksuniversitet.
    Persson, Ingmar
    Sveriges Lantbruksuniversitet.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology. Sveriges Lantbruksuniversitet. Institutionen för mark och miljö.
    Binding of Ag(I) by organic soil Materials and isolated humic substances: XANES Spectroscopy and modeling2013Conference paper (Refereed)
    Abstract [en]

    The binding of silver(I) by organic matter was investigated in batch equilibrations with Suwannee River Fulvic Acid (SRFA), mor (Oe) and peat materials. For the SRFA systems, binding isotherms were determined at pH 4 and 8 using potentiometric titrations, with 0.05 M NaNO3 as background electrolyte. The binding showed a strong pH dependency and was about one order of magnitude stronger at pH 8 compared to pH 4. The data set was consistent with published data sets for isolated fulvic and humic acids. The binding of silver(I) by mor and peat materials was studied as a function of pH in the range 2.5-5.0 in dilute NaNO3 solutions (ca. 0.01 M), at a wide range of silver-to-soil ratios (10-2 – 10-4.5 mol kg-1). The silver(I) binding properties of the two materials were similar, with increasing binding strength with pH. The slope of sorption isotherms determined at pH 2.5 and 4.0 was significantly less than one, indicating heterogeneous binding sites. Ion competition experiments with added 1 mM iron(III) or 1 mM aluminium(III) at pH 2.5 and 4.0 showed no interaction between these ions and the silver(I) ion, indicating highly specific silver(I) binding sites.

    Silver K-edge XANES in the region 25280-26080 eV was used to characterize the binding mode of silver(I) in the mor and peat materials. A silver-to-soil ratio >10-2.5 mol kg-1 was needed to obtain a significant absorption edge. Comparison of spectra with oxygen, sulfur and nitrogen containing model compounds, indicated that the silver(I) ions, on average, was bound to one oxygen and one nitrogen donor ligand in an approximately linear fashion in both samples. Speciation of sulfur in the mor and peat materials using sulfur K-edge XANES, suggested that thiol groups could contribute to maximum about 20% of the silver binding at the conditions used in the Ag K-edge XANES measurements.

    The Stockholm Humic Model (SHM) was used as a tool to make a unified interpretation of SRFA and soil data. First, the model was calibrated using SFRA data together with published data on silver binding to isolated fulvic and humic substances, in order to obtain a consistent generic silver binding parameter set. Second, the calibrated SHM was used to predict the experimental silver(I) binding data obtained with the mor and peat materials. Taking this approach the model largely underestimated the silver(I) binding by the mor and peat materials; roughly by a factor of 10-100, dependent on experimental conditions. Thus, our data suggest that silver(I) binding properties of isolated fulvic and humic acids are very different from those of intact soil and peat materials. This will have great implications for how to calibrate and apply geochemical models describing the behavior of silver(I) in soils and natural waters.

  • 46. Kumar, Manish
    et al.
    Das, Nilotpal
    Goswami, Ritusmita
    Sarma, Kali Prasad
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Ramanathan, A. L.
    Coupling fractionation and batch desorption to understand arsenic and fluoride co-contamination in the aquifer system2016In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 164, p. 657-667Article in journal (Refereed)
    Abstract [en]

    The present work is an attempt to study As and F+ coevality using laboratory based assays which couples fractionation and batch dissolution experiments. Sequential extraction procedure (SEP) resulting into five "operationally defined phases", was performed on sediment and soil samples collected from the Brahmaputra flood plains, Assam, India. High correlation between the Fe (hydr)oxide fraction and total As content of the soil/sediment sample indicates the involvement of Fe (hydr)oxides as the principal source of As. F- being an anion has high potential to be sorbed onto positively charged surfaces. Findings of the SEP were used to design the batch desorption experiments by controlling the Fe (hydr)oxide content of the soil/sediment. Desorption of As and F- was observed under acidic, neutral and alkaline pH from untreated and Fe (hydr)oxide removed samples. Highest amount of As and F- were found to be released from untreated samples under alkaline pH, while the amount leached from samples with no Fe (hydr) oxide was low. The study showed that the Fe (hydr)oxide fraction commonly found in the soils and sediments, had high affinity for negatively charged species like F- oxyanions of As, AsO43- (arsenate) and AsO33- (arsenite). Fe (hydr)oxide fraction was found to play the major role in co-evolution of As and F-. Two sorption coefficients were proposed based on easily leachable fraction and As present in the groundwater of sampling location for understanding of contamination vulnerability from the leaching.

  • 47.
    Larsson, Maja A.
    et al.
    Swedish Univ Agr Sci,Uppsala.
    D'Amato, Marilena
    Italian Natl Hlth Inst, Rome.
    Cubadda, Francesco
    Italian Natl Hlth Inst, Rome.
    Raggi, Andrea
    Italian Natl Hlth Inst, Rome.
    Oborn, Ingrid
    Swedish University of Agricultural Sciences, Uppsala and World Agroforestry Centre (ICRAF) Nairobi.
    Kleja, Dan Berggren
    Swedish Univ Agr Sci, Uppsala and Swedish Geotechnical Institute, Gothenburg.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering. Swedish Univ Agr Sci, Sweden, Uppsala.
    Long-term fate and transformations of vanadium in a pine forest soil with added converter lime2015In: Geoderma, ISSN 0016-7061, E-ISSN 1872-6259, Vol. 259, p. 271-278Article in journal (Refereed)
    Abstract [en]

    A field-trial with different application rates of converter lime (0.2, 0.7 and 1.0 kg m(-2)) was set up in a pine forest stand in southern Sweden in 1984. The lime contained 14.6 g kg(-1) vanadium. The aim with this study was to evaluate the vanadium concentration and speciation in the soil 26 years after application. Samples of the organic mar layer and the mineral soil were analyzed separately. The vanadium concentration decreased with soil depth, from 680 to 8 mg kg(-1) soil. Analysis by vanadium K-edge}CANES spectroscopy showed that vanadium(IV) was the predominant species in the mar layer. Further, iron and/or aluminum (hydr)oxides were important sorbents for vanadium(V) in the mineral soil. The spedation of dissolved vanadium, as determined by HPLC-ICP-MS, was dominated by vanadium(V), which is considered the most toxic vanadium species. However, the vanadium sorption capacity of the soil was sufficient to reduce the total bioavailable vanadium below phytotoxic levels. By combining two different vanadium spedation methods, this study was able to conclude that vanadium speciation in soils is governed by soil properties such as pH, organic matter content and the content of metal (hydr)oxides, but not by the vanadium species added to the soil.

  • 48.
    Lima, Israel Quino
    et al.
    Universidad Mayor de San Andrés, Campus Universitario (UMSA), Cota Cota 27, PO. Box 303, La Paz, Bolivia.
    Muñoz, M. O.
    Ramos, O. E. R.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering.
    Choque, R. Q.
    Aguirre, J. Q.
    Sracek, O.
    Hydrochemical assessment with respect to arsenic and other trace elements in the Lower Katari Basin, Bolivian Altiplano2019In: Groundwater for Sustainable Development, ISSN 2352-801X, Vol. 8, p. 281-293Article in journal (Refereed)
    Abstract [en]

    Hydrochemical investigations of groundwater and surface water were carried out to better understand the spatial distribution of As, major ions and trace elements. The study was carried out to evaluate the sources of dissolved species and elucidate the processes that govern the evolution of natural water in the Lower Katari Basin. The study area is close to the Titicaca Lake (Cohana Bay) formed by sediments of the Quaternary system, deposited in the fluvio-glacial to fluvio-lacustrine environment and geologic formations of the Devonian and Neogene system of volcanic origin. The study area has several environmental problems mainly caused by contaminants such as heavy metals, nutrients, and bacteria. These problems are linked to the urban and industrial wastes, natural geologic conditions, and mining activities carried out upstream of the Katari Basin, where rivers discharge into the Cohana Bay. A total of 37 water samples were collected during wet season, 31 groundwater samples including drinking water wells and six surface water samples. The hierarchical cluster analysis and principal component analysis were applied to hydrochemical data. Results show high salinity in groundwater related to the evaporation causing serious problems for the groundwater quality and rendering it unsuitable for drinking. Dissolved As concentration ranges from 0.7 to 89.7 μg/L; the principal source of As could be the alteration of volcanic rocks, more than 48% of the shallow groundwater samples exceeded the WHO guideline value for As and more than 22% for NO3 -. Groundwater has neutral to slightly alkaline pH, and moderately oxidizing character. The groundwater chemistry reveals considerable variability, ranging from Na-SO4,Cl type through mixed Na-HCO3 type and Ca,Na-HCO3,Cl type. The distribution of trace elements shows a large range of concentrations. Speciation of As indicates that the predominant oxidation state is As (V). The geochemical modelling indicates that As could be associated with iron oxides and hydroxides which are probably the most important mineral phases for the As adsorption. The spatial distribution and the variation of dissolved As concentration in groundwater is governed by the variability in geological characteristics of the region that raises a significant concern about drinking water quality.

  • 49.
    Mahmoudzadeh, Batoul
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Liu, Longcheng
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Neretnieks, Ivars
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Rock fracture closing moderated by pressure solution2015In: Future Communication Technology and Engineering - Proceedings of the 2014 International Conference on Future Communication Technology and Engineering, FCTE 2014, CRC Press/Balkema , 2015, p. 269-275Conference paper (Refereed)
    Abstract [en]

    Fracture apertures may decrease or increase by different mechanical and chemical mechanisms when the fractures are subject to stress. A model is presented to describe fracture closure/opening that accommodates pressure dissolution at contacting asperities as well as free-face dissolution/precipitation at free faces of the fracture and of the rock matrix. The derived analytical model accounts for the fact that dissolved minerals carried by flowing water along the fracture can not only diffuse into and out of the adjacent rock matrix but also at first diffuse into the stagnant water zone existing in part of the fracture plane and then from there into and out of the rock matrix adjacent to it. The analytical solution is used to study fracture closure/opening rate in a pseudo steady state, PSS, procedure. This simple model allows us to gain some insights into which processes and mechanisms have the larger impact on the fracture aperture under different circumstances.

  • 50.
    Markidis, Stefano
    et al.
    KTH, School of Computer Science and Communication (CSC), Centres, Centre for High Performance Computing, PDC.
    Henri, P.
    Lapenta, G.
    Divin, A.
    Goldman, M. V.
    Newman, D.
    Eriksson, S.
    Collisionless magnetic reconnection in a plasmoid chain2012In: Nonlinear processes in geophysics, ISSN 1023-5809, E-ISSN 1607-7946, Vol. 19, no 1, p. 145-153Article in journal (Refereed)
    Abstract [en]

    The kinetic features of plasmoid chain formation and evolution are investigated by two dimensional Particlein-Cell simulations. Magnetic reconnection is initiated in multiple X points by the tearing instability. Plasmoids form and grow in size by continuously coalescing. Each chain plasmoid exhibits a strong out-of plane core magnetic field and an out-of-plane electron current that drives the coalescing process. The disappearance of the X points in the coalescence process are due to anti-reconnection, a magnetic reconnection where the plasma inflow and outflow are reversed with respect to the original reconnection flow pattern. Anti-reconnection is characterized by the Hall magnetic field quadrupole signature. Two new kinetic features, not reported by previous studies of plasmoid chain evolution, are here revealed. First, intense electric fields develop in-plane normally to the separatrices and drive the ion dynamics in the plasmoids. Second, several bipolar electric field structures are localized in proximity of the plasmoid chain. The analysis of the electron distribution function and phase space reveals the presence of counter-streaming electron beams, unstable to the two stream instability, and phase space electron holes along the reconnection separatrices.

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