Pollution Assessment of Trace Metals in Ground Waters (Case Study: Meshgin Shahr County)

Abstract

In this research, the data of wells in operation, deep and semi-deep wells were studied for assessment of trace elements of wells in Meshgin Shahr plain zone. Digital data were obtained using Arc GIS software. Using systematic random selection method, 46 wells were considered as the statistical population. For preparing zoning maps, after investigating a spatial correlation among the observed values, feasibility of preparing the underlying maps was studied using geostatistics methods such as inverse square distance and Kriging methods. Findings of the study indicated presence of trace metals (zinc and copper) in water. Considering continued trend of pollution and limited amount of aquifers, it will have, certainly, various environmental risks in long term. Hence, qualitative and quantitative protection and preventing increasing pollution of water, due to limited water resources in Meshgin Shahr plain, are among the main principles of planning in line with population and industrial development and excessive exploitation of Meshgin Shahr plain aquifer should be considered as the main factor in generation of chemical pollution. Findings of the study indicated that there is a significant difference between concentration of zinc and copper elements in the studied well waters. The highest average concentration is related to zinc element and the lowest concentration of trace metal is related to copper. The main reasons of trace elements presence are maternal stones storage capacity and transferring it to the ground waters. The two elements of zinc and copper are above the related standards specially at the north part of the area. Although type of the lithology affects amount of silicate and non-silicate minerals and considering diversity of lithology and concentration of human activities and residence at the elevation aligned foothills and plain lands have caused human factors (using chemical fertilizers, detergents) they cause accumulative effects on the above mentioned elements.