Distribution, source identification, and contamination level of trace metals in the sediment of the Shari-Goyain River in Bangladesh: Implications for ecological health risks

The major issue associated with coal mine drainage is its contribution to river pollution, which occurs at the local, regional, and global levels. The pollution of surface sediment by heavy metals is a major environmental and health concern in coal mining and downstream areas. This study explored the concentrations of eight metal components in the sediments from the Shari-Goyain River of Bangladesh. The trend of decreasing metal concentration was identified as Fe > Mn > Ni > Zn > Cu > Cr > Pb > Cd in sediment. The level of metal pollution in the study area was assessed by using various indicators like geo-accumulation index (I_geo), pollution load index (PLI), contamination factor (CF), potential ecological risk factor, and risk index (RI). The sediment in the river exhibited PLI values ranging from 0.133 to 0.543, suggesting a low level of pollution from the evaluated heavy metals (PLI < 1). The mean I_geo showed that the study area was unpolluted whereas Ni showed unpolluted to moderately polluted status. For most of the metals, the sediment samples recorded a low degree of contamination (CF < 1) except Pb, Cd, and Ni which exhibited moderate degree of contamination (1 ≤ CF < 3). Through the application of various statistical analyses, coal mine drainage has been identified as the possible source of pollution of the analyzed metals in the Shari-Goyain River. However, the risk index and RI suggested a low risk of metal pollution in the studied areas. To improve the environmental conditions of the Shari-Goyain River, it is crucial to construct permanent sediment quality monitoring stations and conduct extensive ecological investigations.