Integrated Study of Physico-Chemical Parameters and Heavy Metal Distribution in Freshwater Lakes of Chitradurga, Karnataka, India

Abstract

Freshwater ecosystems in semi-arid regions of India are increasingly threatened by anthropogenic pressures, necessitating integrated assessments of water quality and heavy metal contamination. This study investigates the physicochemical parameters and heavy metal distribution across four lakes—Gonur, Mallapura, Matadahatti Kere, and Chandravalli—in Chitradurga, Karnataka, from July to December 2024. Systematic sampling and analysis were conducted to evaluate pH, total dissolved solids (TDS), electrical conductivity (EC), turbidity, alkalinity, hardness, and concentrations of key ions and nutrients. Concurrently, heavy metals including chromium (Cr), lead (Pb), copper (Cu), iron (Fe), nickel (Ni), and zinc (Zn) were quantified using Atomic Absorption Spectroscopy (AAS). Results revealed seasonal fluctuations in physicochemical parameters, with elevated TDS and EC during monsoon and pre-monsoon periods, attributed to agricultural runoff and reduced dilution. Alkalinity and hardness peaked in summer, indicating increased decomposition and mineralization. Notably, Mallapura Lake exhibited the highest levels of pollution, with TDS reaching 688 mg/L and EC exceeding 1200 µS/cm. Heavy metal concentrations varied across lakes, with Cr and Pb frequently surpassing permissible limits set by BIS and WHO, particularly in Mallapura and Gonur Lakes. Cu and Fe levels were elevated in all lakes, while Ni and Zn remained within acceptable thresholds. The presence of non-biodegradable metals in sediments and water poses significant ecological and public health risks, including bioaccumulation and biomagnification through aquatic food webs. Seasonal variations in metal concentrations suggest remobilization driven by changes in pH, redox potential, and microbial activity. The study underscores the urgent need for sediment remediation, community education, and policy interventions to mitigate contamination sources. By integrating physicochemical profiling with geospatial mapping and heavy metal analysis, this research provides a comprehensive environmental status of Chitradurga’s lakes. The findings contribute to regional water quality databases and offer actionable insights for sustainable lake management, ecological restoration, and public health safeguarding in vulnerable freshwater habitats.