Heavy Metal Contamination and Its Chemical Effects on Water Quality

Abstract

Heavy metals and metalloid elements can enter aquatic environments through mining, industrial activities, wastewater discharge, agriculture, urban runoff, and natural geological processes. Metals such as lead, mercury, cadmium, chromium, arsenic, copper, and nickel can influence water quality through changes in chemical composition, speciation, solubility, redox behavior, and interactions with sediments and dissolved organic matter. Their environmental significance depends not only on total concentration but also on chemical form and bioavailability. Heavy-metal contamination can affect aquatic organisms and create concerns for drinking-water resources and food chains. This paper examines nine major dimensions of heavy-metal contamination, including sources, chemical speciation, water chemistry, sediment interactions, bioavailability, ecological effects, human-health concerns, monitoring, and remediation.