Heavy metals in riverine ecosystems pose long-term risks to water security and aquatic organisms. A quantitative analysis of seven heavy metals—Cr, Cd, Fe, Pb, Zn, Cu, and Ni—in water and sediment samples at 18 strategic locations of Kerala's Kallada River over a 12-month period (Feb 2018–Jan 2019) in the present study was done. Using atomic absorption spectroscopy and statistically intensive treatment, the research aimed to determine patterns of contamination as well as seasonality. Significantly, the chromium levels in water were above limits in all monsoon stations, including an upper limit of 0.5684 ppm in upstream segment (S6). Copper was above the limits in midstream and downstream areas in postmonsoon, while the highest value of iron in sediment was 140.1 mg/kg at S18. Sediment analysis showed levels of lead (2.315 mg/kg) and chromium (6.14 mg/kg) above normal at certain downstream locations. Pearson correlation indicated strong relationships, i.e., Cu-S and Pb-S (r = 0.86753). Implications include industrial effluents, agricultural runoff (copper fungicides in particular), and municipal solid waste. Although water samples as a whole were in conformity with standards, sediment displayed latent ecological threats. The study concludes on recommending routine monitoring of water quality, strict control of effluent disposal, and implementation of sustainable waste management policy to promote aquatic and human health safety.
Krishnan et al. (Thu,) studied this question.