Bioaccumulation of Heavy Metals and Their Ecotoxicological Impacts on Selected Fish Species in Jaipur District Ponds.

Abstract

Introduction: Aquatic ecosystems are highly vulnerable to heavy metal contamination from industrial effluents, sewage, and agricultural runoff. Unlike biodegradable pollutants, heavy metals are persistent, bioaccumulate in fish, and pose ecological and human health risks through food webs. Fish, serving as bioindicators, accumulate toxic metals in tissues like gills, liver, and muscles, leading to physiological stress, oxidative damage, and mortality. In Jaipur, Rajasthan, freshwater bodies such as Jal Mahal Lake and Neota Dam face increasing pollution threats. This study investigates heavy metal bioaccumulation in fish species from these sites, aiming to assess ecotoxicological impacts and support sustainable aquatic resource management.

Methods: The study was conducted in two contrasting freshwater bodies of Jaipur: Jal Mahal Lake, impacted by sewage, runoff, and tourism, and Neota Dam, a less urbanized reservoir. Seasonal fish sampling was carried out at four sites per water body using gill nets during evening and morning hours. Collected specimens were identified, measured, sexed, and preserved in formaldehyde. Tissues (gills, liver, muscle) were dissected, washed, dried, homogenized, and digested with HNO₃: HClO₄. Heavy metals (Cd, Pb, Cr, Cu, Zn) were quantified using Atomic Absorption Spectrophotometry (AAS), with calibration against certified standards, blanks, and triplicate analyses ensuring reliability.

Results: Comparative assessment indicated that Jal Mahal Lake harbored higher contamination levels than Neota Dam, reflecting the influence of urbanization, sewage inflow, and anthropogenic disturbances. The calculated Bioaccumulation Factors (BAFs) confirmed active uptake of toxicants, while health risk assessments (THQ, HI) revealed that consumption of fish from these water bodies could exceed permissible exposure limits, particularly for Cd and Pb, leading to long-term health risks such as neurotoxicity, renal dysfunction, and developmental impairments.
Conclusions: The study concludes that fish in Jaipur’s freshwater bodies exhibit significant heavy metal bioaccumulation, with liver and gills most affected, while muscle tissues also contained toxic metals posing health risks to consumers. Jal Mahal Lake showed higher contamination than Neota Dam, reflecting greater urban and sewage impacts. Bioaccumulation factors and health risk indices confirmed potential threats, especially from cadmium and lead. The findings highlight ecological disruption, biodiversity loss, and human health hazards. Recommendations include regular monitoring, strict pollution control, public health awareness, bioremediation, eco-restoration, stronger governance, and further research on sediments, trophic transfer, and biomarkers for early toxicity detection.