In order to understand, interpret and evaluation of soil and water contamination of any region, having information about geological conditions is essential. The study area (Sefid rud basin) is located in Gilan province. To investigate the source and parameters that affe More
In order to understand, interpret and evaluation of soil and water contamination of any region, having information about geological conditions is essential. The study area (Sefid rud basin) is located in Gilan province. To investigate the source and parameters that affect arsenic concentrations in the Sefid rud basin, 336 samples from 48 stations (over 9 month) and chemical analysis (61 rock samples and 18 sediment samples) were analyzed. Results showed that As levels in some parts of the study area is exceeds the standard limit. Based on calculation of concentration ratio, the measured elements in most samples had a higher concentration than the Clark value, which indicates rock unites had a great potential impact of contamination on the Sefid Rud basin.
Hydrogeochemical parameters of surface and ground waters as well as mineral assemblage and sedimentological characteristics were examined. The highest levels of arsenic contamination were observed in Fakhrabad and Salekdeh wells during October and November. Measured correlation coefficients showed that Nitrate and DO values have negative correlation with arsenic concentration of surface and ground waters. Hydrogeochemical information indicated arsenic release into surface and ground waters of study area is controlled by complicated processes which includes: 1. Arsenic dissolution from Fe oxy-hydroxides as the main process 2. Decomposition and weathering of rocks and minerals of the study area 3.Mineralogical composition of the aquifer 4. Intrusion of seawater and increased salinity 5. Human activities.
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