Distribution Pattern of the Heavy Metals in Stream Sediments at the East and Southeast of Angouran Mine, West of Zanjan

Abstract In order to assess the concentrations of heavy metals in stream sediments of eastern and southeastern drainages of the Angouran Zn-Pb mine, stream sediment samples were selected from 77 stations. Results of samples analysis demonstrate that concentrations of As, Sb, Cd, Pb and Zn are higher and Co is less than the averages of upper continental crust in most stations. The elements correlation analysis indicates that there are intermediate to very strong positive correlations between Pb, Zn, Cd, Sb and As, and Co has no correlation with other elements. Investigation of distribution maps, enrichment factor and geo-accumulation index demonstrate that the highest enrichment and pollution in the study area related to Pb, Zn, Cd, Sb and As which are concentrated at the northern and northeastern parts of the study area (Allahlou-Chay catchment). Investigation of the relationship between the obtained data and geology of the study area demonstrates that the origin of these elements concentrations are geogenic and related to mineralizations and alterations. Exploitation activities at the Angouran Zn-Pb mine caused increasing the concentration of heavy metals and their entry into the surface waters which with the result of expansion of mentioned elements to northeast of study area and Allahlou-Chay catchment. Keywords: Stream sediment, Heavy metals, Spatial distribution, Geo-accumulation index, Angouran. Introduction Heavy metals are one of the most important soil contaminants which are naturally present in the soil, but large amounts of these metals are the result of human activities like mining, transportation, disposal of industrial wastewater, improper disposal of wastes and use of chemical fertilizers and pesticides (Rahimpour and Abbaspour 2014; Zare Khosh Eghbal et al. 2012). Seasonal rivers during heavy rains transfer contaminated sediments and mineral waste from adjacent mines to downstream areas and cause heavy metal dispersion. As such, studying stream sediments is one of the best ways to assess pollution. Angouran Zn-Pb mine is one of the mines that due to a large volume of extraction and mineral production has produced a lot of waste around the mine. These wastes, in turn, can cause many problems for the environment around the mine. In this study, an attempt was made to evaluate the role of mining in the environment by investigation of heavy metal concentrations in the stream sediment samples of the rivers at the east and southeast of the An