Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Phosphorus transport in shallow groundwater in peri-urban Kampala, Uganda: results from field and laboratory measurements
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
2008 (English)In: Environmental Geology, ISSN 0943-0105, E-ISSN 1432-0495, Vol. 53, no 7, 1535-1551 p.Article in journal (Refereed) Published
Abstract [en]

To understand Phosphorus (P) sources and transport processes in the subsurface in Bwaise III Parish, Kampala, P attenuation and adsorption capacities of soils were studied in situ and from laboratory measurements. Relationships between sorption parameters and soil matrix properties, rates and mechanism of the adsorption process and soil P fractions were also investigated. P was generally higher in the wet than the dry season, but for both seasons, the maximum was 5 mgP/l. P transport mechanisms appeared to be a combination of adsorption, precipitation, leaching from the soil media and by colloids with the latter two playing an important role in the wet season. The sorption process comprised two phases with the first stage rate constants being about fourfold those of the second stage. The Langmuir isotherm described the sorption data well (R-2 >= 0.95) with the second soil layer exhibiting the highest sorption maximum (C-max) (average value 0.6 +/- 0.17 mgP/gDW). The best prediction of C-max had organic carbon, Ca, available P and soil pH. Residual P consisting mostly of organics was the main fraction in all the layers followed by inorganic HCl-P and NaOH-P in the top and middle layers, respectively. Loosely bound P (NH4Cl-P) was the least fraction (< 0.4% of total P) in all layers indicating the high binding capacity of P by the soils. The study results suggest that P dynamics is related to Ca, Fe and organic carbon content of the soils.

Place, publisher, year, edition, pages
2008. Vol. 53, no 7, 1535-1551 p.
Keyword [en]
peri-urban, Phosphorus, shallow groundwater, adsorption, Uganda, soil, sorption, phosphate, sediments, water, adsorption, fractions, leachate, duckweed, release
Identifiers
URN: urn:nbn:se:kth:diva-17268DOI: 10.1007/s00254-007-0764-0ISI: 000252276100017Scopus ID: 2-s2.0-38149047526OAI: oai:DiVA.org:kth-17268DiVA: diva2:335311
Note
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Environmental sanitation situation and solute transport in variably saturated soil in peri-urban Kampala
Open this publication in new window or tab >>Environmental sanitation situation and solute transport in variably saturated soil in peri-urban Kampala
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The environmental sanitation situation in Kampala’s peri-urban areas was reviewed and investigated through field studies, structured interviews with personnel from key institutions and administration of questionnaires to households in a selected peri-urban settlement (Bwaise III Parish).  In this settlement, specific field and laboratory measurements were undertaken so as to create a better understanding of the environmental sanitation situation, anthropogenic pollution loads and their transport and impact (with a focus on Phosphorus) in Kampala’s Peri-urban areas in pursuit of interventions for improving the environmental sanitation and protecting the shallow groundwater resource there. The review revealed that the urban poor in Kampala, like elsewhere in developing countries, are faced with inadequate basic services caused by a combination of institutional, legal and socio-economic issues and that the communities’ coping strategies are in most cases detrimental to their health and well-being. Field surveys showed that excreta disposal systems, solid waste and greywater are major contributors to the widespread shallow groundwater contamination in the area. Field measurements revealed that the water table responds rapidly to short rains (48 h) due to the pervious (10-5-10-3 m/s) and shallow (<1 mbgl) vadose zone, which consists of foreign material (due to reclamation). This anthropogenically influenced vadose zone has a limited contaminant attenuation capacity resulting in water quality deterioration following rains. The only operational spring in the area is fed by regional baseflow meaning a wider protection zone. The spring discharge exhibited microbial quality deterioration after rains primarily as a result of poor maintenance of the protection structure. Subsurface phosphorus (P) transport mechanisms appeared to be a combination of adsorption, precipitation, leaching from the soil media and through macropore flow with the latter two playing an important role in the wet season. The Langmuir isotherm described the phosphorus sorption data well (R2³ 0.95) and the best prediction of Langmuir sorption maximum (Cmax) had organic carbon, Ca and available phosphorus and soil pH as significant predictors. Loosely bound P (NH4Cl-P) was the least fraction (<0.4% of total P) in all layers indicating a high binding capacity of P by the soils implying that the soils have a capacity to adsorb additional P loads. Simulation results from the preliminary numerical model built in this study based on field and laboratory measurements indicate that rainfall infiltration rates > 7x10-3 mm/s drive shallow groundwater contamination with higher intense rains of relatively longer duration (³ 70 mm within 48 h) reducing phosphorus transport. Sensitivity analysis of the model input with respect to how long it takes to pollute the subsurfacehad the phosphorus sorption coefficients as being more influential than the pore size and air entry values. There are however, key contrasts between the model simulations and field observations which are useful in guiding new efforts in data collection. The study reveals that intervention measures to improve the environmental sanitation and protect the shallow groundwater in the peri-urban settlements are of a multidisciplinary nature necessitating action research with community participation.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. xiv, 60 p.
Series
Trita-LWR. PHD, ISSN 1650-8602 ; 1059
Keyword
Environmental Sanitation, Kampala, Modelling, Phosphorus transport, Shallow groundwater, Peri-urban, Vadose zone
National Category
Other Environmental Engineering
Identifiers
urn:nbn:se:kth:diva-24595 (URN)978-91-7415-728-4 (ISBN)
Public defence
2010-09-30, Makerere University, Uganda, 09:15 (English)
Opponent
Supervisors
Note
QC 20100917Available from: 2010-09-17 Created: 2010-09-17 Last updated: 2010-12-01Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Kulabako, N. R.Thunvik, Roger
By organisation
Environmental Management and Assessment
In the same journal
Environmental Geology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 51 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf