Why in news?
A comprehensive study published in Environmental Earth Sciences has highlighted alarming levels of heavy metals in sediments and fishes of the Cauvery River. Researchers found that elements such as lead, cadmium, chromium, nickel and mercury are accumulating in the river’s sediments and entering aquatic food chains, posing risks to wildlife and people who consume fish from the river.
Background
Heavy metals are dense elements like mercury, lead, cadmium and arsenic that are toxic even at low concentrations. They do not break down in the environment and therefore persist in soil and water. Industrial waste, mining, improper waste disposal and polluted rainwater can introduce heavy metals into rivers. Over time these metals settle into sediments and bioaccumulate in plants and animals. Humans are exposed through drinking water or by eating contaminated fish and crops.
What the study found
- Extensive sampling: Scientists collected sediment and fish samples from multiple sites along the Cauvery River and used sophisticated analytical techniques to measure metal concentrations.
- Persistent pollutants: Lead, cadmium, chromium, nickel and mercury were detected in all samples. Industrial zones downstream showed especially high contamination levels.
- Bioaccumulation in fish: Carnivorous fish had higher levels of mercury and lead than omnivorous species, showing that metals move up the food chain. Some fish tissues exceeded safety thresholds for human consumption.
- Health risks: The researchers used risk assessment models to estimate potential human health impacts. Hazard quotients for certain metals were above safe limits, indicating possible effects such as neurological and kidney damage if contaminated fish are eaten regularly.
- Environmental impact: Heavy metals harm aquatic life by disrupting metabolism, reproduction and growth. They also degrade sediment quality and can be released back into the water under changing environmental conditions.
Recommendations
- Improved regulation: The study urges stricter control of industrial effluents and proper waste management to reduce metal discharge into rivers.
- River basin management: Integrating pollution control with afforestation of riverbanks, sustainable farming practices and community‑based monitoring can help restore river health.
- Public awareness: Educating communities about the risks of consuming contaminated fish and promoting regular testing of fish caught for food are essential.
Conclusion
Heavy metals pose a silent but serious threat to the Cauvery River’s ecosystems and to people who rely on its waters for sustenance. The study’s findings underscore the need for concerted action by industries, regulators and communities to curb pollution and protect this vital river.
Source: Scienmag