Arsenic and associated trace-elements in groundwater from the Chaco-Pampean plain, Argentina: Results from 100 years of research
2012 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 429, 36-56 p.Article, review/survey (Refereed) Published
The Chaco-Pampean plain, Argentina, is a vast geographical unit (1,000,000 km(2)) affected by high arsenic (As) concentrations in universal oxidizing groundwater. The socio-economic development of the region is restricted by water availability and its low quality caused by high salinity and hardness. In addition, high As and associated trace-elements (F, U, V. B, Se, Sb, Mo) concentrations of geogenic origin turn waters unsuitable for human consumption. Shallow groundwater with high As and F concentrations (ranges: <10-5300 mu g As/L; 51-7,340 mu g F/L) exceeding the WHO guideline values (As: 10 mu g/L; F: 1,500 mu g/L) introduces a potential risk of hydroarsenicism disease in the entire region and fluorosis in some areas. The rural population is affected (2-8 million inhabitants). Calcareous loess-type sediments and/or intercalated volcanic ash layers in pedosedimentary sequences hosting the aquifers are the sources of contaminant trace-elements. Large intra and interbasin variabilities of trace-element concentrations, especially between shallow and deep aquifers have been observed. All areas of the Chaco-Pampean plain were affected in different grades: the Chaco-Saltena plain (in the NNE of the region) and the northern La Pampa plain (in the center-south) have been shown the highest concentrations. The ranges of As and F contents in loess-sediments are 6-25 and 534-3340 mg/kg, respectively in the Sali River basin. Three key processes render high As concentrations in shallow aquifers: i) volcanic glass dissolution and/or hydrolysis and leaching of silicates minerals hosted in loess; ii) desorption processes from the surface of Al-, Fe- and Mn-oxi-hydroxides (coating lithic fragments) at high pH and mobilization as complex oxyanions (As and trace elements)in Na-bicarbonate type groundwaters; and iii) evaporative concentration in areas with semiarid and arid climates. Local factors play also an important role in the control of high As concentrations, highly influenced by lithology-mineralogy, soils-geomorphology, actual climate and paleoclimates, hydraulic parameters, and residence time of groundwaters.
Place, publisher, year, edition, pages
2012. Vol. 429, 36-56 p.
Hydrogeochemistry, Trace-element sources and mobility, Arsenic, Fluoride, Chaco-Pampean aquifers, Endemic hydroarsenicism and fluorosis
IdentifiersURN: urn:nbn:se:kth:diva-102643DOI: 10.1016/j.scitotenv.2012.04.048ISI: 000307085100003ScopusID: 2-s2.0-84862256232OAI: oai:DiVA.org:kth-102643DiVA: diva2:556063
QC 201209242012-09-242012-09-212012-09-24Bibliographically approved