Heavy metals are metallic elements with high atomic weights that can be toxic to organisms even at low concentrations. Common heavy metal contaminants in water include lead, mercury, arsenic, cadmium, and chromium.
Heavy metals in water refer to a group of metallic elements including lead (Pb), mercury (Hg), arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), zinc (Zn), and nickel (Ni) that can accumulate in aquatic environments and pose significant health and ecological risks. These metals enter water bodies through industrial discharges, mining operations, agricultural runoff, urban stormwater, atmospheric deposition, and natural weathering of mineral deposits. Unlike organic pollutants, heavy metals are not biodegradable and tend to bioaccumulate in the food chain, with top predators such as large fish accumulating the highest concentrations. The EPA has established maximum contaminant levels (MCLs) for several heavy metals in drinking water, including 0.015 mg/L for lead and 0.002 mg/L for mercury. Chronic exposure to heavy metals through contaminated drinking water can cause neurological damage, kidney disease, cancer, and developmental disorders in children. Treatment technologies for heavy metal removal include chemical precipitation, ion exchange, activated carbon adsorption, membrane filtration, and constructed wetlands. Sediment sampling and biomonitoring using organisms such as mussels and aquatic insects are common approaches for assessing heavy metal contamination in waterways.