Heavy metal distribution and ecological pollution assessments in water bodies and sediments in rural areas of Bangladesh

Pollution in rural waterbodies, sediments, and aquatic species due to long-range transportation and mobilization of heavy and toxic metals contaminants is a growing concern in many developing countries nowadays. Environmental components in rural areas are usually considered as safe and information on metals toxicities in rural natural resources are very limited. Herein, accumulation, mobilization, and distribution of eight different elements (Fe, Ni, Mn, Pb, Cr, Cu, Cd, As) in water bodies and sediments in rural areas of Bangladesh have been investigated successfully. Different metals contents found in water and sediment were compared with standard threshold levels reported by WHO, USEPA, China, and the results revealed the occurrence of pollution in respective environmental resources with the excessive presence of some heavy metals. Pollution characteristics analyses with trace metal pollution index (TPI), heavy metal evaluation index (HEI), contamination index (Cd), and comprehensive pollution index (CPI) indicated that water bodies in rural areas are contaminated with Pb, Mn, Fe, and different metals contents were varied in the order of Fe > Mn > Cu > Pb > Cr > As > Cd > Ni (mg/L). Contamination analyses in sediments with potential ecological risk index (PERI), pollution load index (PLI), metal enrichment (EF), and geo-accumulation index (I_geo) assessments revealed the occurrence of pollution in sediments with Ni, Cr, Cu, and the translocations of different heavy metals in rural sediments were varied in the order Fe > Mn > Cr > Ni > Cu > Cr > Cu > Pb > As > Cd (mg/Kg). PLI data of metals showed higher than one and the magnitudes of I_geo were greater than zero which indicated inordinate accumulation of Ni, Cr, and Cu in sediments. The present research findings offer significant information on how the pollutants from point sources impact the environmental ecosystems in rural areas of Bangladesh due to the long-range pollution with flood and other natural disasters that occur frequently in the region. These results may be useful for making necessary environmental policies in developing countries regarding long-range pollution.