Assessment of Metallic Pollution along with Geochemical Baseline of Soils at Barapukuria Open Coal Mine Area in Dinajpur,Bangladesh

A total 42 (5 + 37) soil samples surrounding 4 km² of Barapukuria open coal mine area were collected to determine the geochemical baseline and concentrations of different metals after digestion with aqua regia. The mean total concentration and geochemical baseline values of Cu, Zn, Pb, Cd and Cr in soil samples were 28.43, 44.83, 20.94, 0.19 and 55.79 μg g⁻¹, and 20.40, 32.80, 20.47, 0.12 and 42.69 μg g⁻¹, respectively. Out of 37 sampling stations, 92-100% locations had the values higher for Cu, Zn, Cd and Cr, while it was 65% for Pb, than that of the geochemical baseline value. The deposition of outlet fly ash and waste water may be responsible to increase metal concentrations in surface soils around the coal mining area. Copper, Zn, Cd, Cr and Pb concentrations upto carbonate bound fraction were 2.52-17.12, 2.62-40.67, 0, 1.47-17.62 and 4.53-16.10 μg g⁻¹, respectively. Zinc, Cu, Cd and Cr were the major pollutants in the surrounding soils of Barapukuria because these metals have contamination factor >1.0 for most sampling stations. Study also revealed moderate pollution level by these metals after calculated I_geo values. According to risk assessment code, although adjacent soils of Barapukuria are contaminated with Cu, Zn, Cd, Cr and Pb but these metals are relatively strongly bound to the soils and are of low risk (<10% for these metals) as regards to mobilization. The study results inferred that if proper attention is ignored, the concentration of metals will increase to intolerable limits that may have severe impacts on the soil environment.