Assessment of Heavy Metal Contamination in Aquatic Fauna Using Atomic Absorption Spectroscopy

Abstract

This study investigates the extent of heavy metal contamination in freshwater fish tissues across industrial, urban, agricultural, and pristine sites using Atomic Absorption Spectroscopy (AAS) for precise quantification of lead (Pb), cadmium (Cd), chromium (Cr), and mercury (Hg). A total of 150 samples were analyzed, revealing concentrations of all metals exceeding FAO permissible limits, with the liver showing the highest accumulation (Pb: 3.37 mg/kg; Cd: 1.02 mg/kg; Cr: 1.58 mg/kg; Hg: 0.57 mg/kg), followed by gills and muscle tissues. Spatial variation analysis indicated significantly elevated levels in industrial and urban drainage zones compared to reference sites, confirming anthropogenic sources such as metal plating, textile effluents, and agricultural runoff. Bioaccumulation Factor (BAF) and Health Risk Index (HRI) values were significantly higher (p < 0.001) in contaminated regions, with cumulative Hazard Index (HI = 5.55) surpassing safe limits, indicating substantial ecological and human health risks through fish consumption. The findings demonstrate that industrial and agricultural discharges are primary contributors to persistent aquatic pollution, leading to potential bioaccumulation and chronic toxicity. Therefore, this research underscores the urgent need for continuous biomonitoring, strict enforcement of effluent regulations, and adoption of sustainable pollution management strategies to mitigate heavy metal exposure and preserve aquatic ecosystem integrity.