Investigation of as distribution and geochemica parameters Affecting its Dissolution and mobility in water resources of Sefid Rud
Subject Areas :
Keywords: Arsenic, Hydrogeochemistry, Sefid Rud basin, arsenic mobility,
Abstract :
In order to study the effect of hydrogeochemical parameters on arsenic contamination level, the surface andgroundwater samples were examined in the Sefid Rud basin. Statistical analyses display medium correlationbetween physicochemical parameters (such as EC, BOD, TDS, COD) and abundance of arsenic in surfaceand groundwaters of the study area. As abundance shows indirect correlation with nitrate and Do in surfaceand groundwater samples. The highest As contamination levels were observed in Fakhrabad and Salkadehduring October and November. The multivariate statistical and graphical techniques were used to identifythe sources of arsenic along the river basin. Hydrogeochemical parameters of surface and groundwatersamples plus mineral assemblages and sedimentological characteristics of the quaternary alluvial wereexamined in the Sefid Rud basin where As concentration in the samples is highly variable in differentplaces.The hydrogeochemical data suggest that the releasing of As into surface and groundwaters of thestudy area is controlled by complex processes including: 1) the dissolution of As from surface of Feoxyhydroxide minerals as the primary mechanism responsible for releasing As into surface andgroundwaters, 2) weathering of minerals and rocks, 3) mineralogical composition of aquifer, 4) salt input(from evaporate deposits), 5) ion exchange processes (clay minerals in sedimentary rocks), 6) velocity andvolume of groundwater flow, 7) precipitation and 8) anthropogenic activities.