Source identification and potential risk assessment of heavy metals in Damodar River in West Bengal, India

Land use directly controls the river water pollution of a region throughout the year, as all the pollutants from the basin come through sewages (point source). The toxicity of heavy metals (HMs) causes health hazards to the people of the Damodar River basin. Arsenic, lead, copper, cadmium, chromium, nickel, mercury and zinc are tested from the collected water sample in the post-monsoon season to identify the sources of heavy metals that come from point sources of pollution. A detailed field-based study identifies arsenic contamination in rivers from industrial and mining areas. High nickel trace in water due to the sewages from iron and steel manufacturing industries in the study area. Lead in the Damodar River comes from mining areas. Mercury in water is a source from industrial and mining sites in Majhermana and Barakar. The Damodar River water quality has improved in the last 3–4 years. Only arsenic and nickel have higher concentrations above or near the permissible limit. Mercury and lead concentrations are also not satisfactory. Other heavy metals like cadmium, zinc, chromium, and copper are well below the detection limit, and in some cases, almost no concentration is found. The carcinogenic risk is maximum from the arsenic and nickel in water. 241–999 people per million population have a potential threat of cancer from arsenic and nickel in the cumulative total risk (TR) assessment. These heavy metals can enter our bodies by direct ingestion or inhalation. The excess lifetime cancer risk (ELCR) is also significantly higher for arsenic and nickel.