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Munkhtsengel Baatar, Mongolian University of Science and Technology (Mongolia)
Gerel Ochir, Mongolian University of Science and Technology (Mongolia)
Noriyoshi Tsuchiya, Tohoku University (Japan)
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Main objective of our study is to know how is heavy metal, especially Cu and Mo contamination in soil and river water in the area of Erdenet Mine, how the pollution is distributed in far extended area. We collected soil (totally 110) and river water (14) samples from 150 x 120 km area. Soil samples were analyzed for major, trace elements and heavy metal contents (XRF) and water samples for the trace element and heavy metals (ICP-MS and AAS). Soil samples are also collected by cross section from seven sites depending on their location and distances from the origin of heavy metal distribution. Evaluation of obtained analysis of soil samples indicates that some of heavy metals; especially Cu and Mo are enriched in soils near open pit and tailing dam. There is clear evidence that Cu and Mo distribution differs by direction and distance from the origin. Heavy metals, especially target metal Cu and Mo, are distributed higher in closer places to open pit and tailing, especially just between the open pit and tailing dam and in eastern side compare to other places. For instance, Cu content of soil decreases in far eastern side of open pit and Mo in river water show similar distribution within the area.
The experimental analysis of HCl acid extraction of soil shows the heavy metal content that not exceeded than environmental standard limit. Based on cross section analysis, it is clear that Cu and other heavy metals pollute the surface than lower sections and this behavior is clearer in cross sections near the open pit and tailing dam. Some elements such as As, B, F, NO3- and Fe are higher than drinking water standard in river water samples from the Erdenet River site close to the tailing dam. In order to better understand the correlation between elements through environment, we conducted multivariate elemental calculation on rock, soil and river water samples from the study area. The software, ThinkSTAT for Excel Multivariate Analysis is applied for the calculation of elemental correlation. Based on correlation coefficient (r) we discuss the element relationships within the samples.
Correlation coefficient of Cu and Mo is moderate (r = 0.59) within Erdenet Porphyry Association rock samples, which are source of those two elements, while it is increased in soil (r = 0.83) indicating the later effect of Cu and Mo to the soil, in a current situation the Erdenet mining impact.
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