Syllabus: GS3/Pollution
Context
- A recent study, published in Environmental Earth Sciences, reveals alarming levels of heavy metal contamination in fish species of Cauvery River, posing serious risks to ecosystems and public health.
About the Heavy Metals
- These are naturally occurring elements with high atomic weights and densities.
- While some like iron and zinc are essential in trace amounts, others such as lead, mercury, arsenic and cadmium are toxic even at low concentrations.
- These pollutants settle in river sediments and bioaccumulate in aquatic life, entering the human food chain through fish and drinking water.
Sources of Contamination
- Anthropogenic sources like coal mining, smelting, leather tanning, and many more.
- Natural sources: Some heavy metals are naturally present in groundwater due to seepage from rocks, volcanic activities and forest fires
Contamination in Water Bodies
- River System: According to the Central Water Commission (CWC), toxic metals such as arsenic, cadmium, chromium, copper, nickel, and lead etc were found in concentrations exceeding permissible limits.
- Rivers like the Ganga, Yamuna, Cauvery, and Arkavati showed multi-metal pollution, often linked to industrial discharge and untreated sewage.
- Groundwater Contamination: The Ministry of Jal Shakti confirmed that 36,873 rural habitations were affected by heavy metal contamination in groundwater.
- Arsenic and fluoride were the most common pollutants, with cadmium and lead present in isolated pockets.
- Contamination in Food Sources: Fish from the Cauvery River and Kochi backwaters contained dangerous levels of mercury, lead, and cadmium.
- Vegetables sold in Bengaluru markets were found to contain heavy metals beyond safe limits, according to a study by EMPRI Karnataka.
Impacts of Heavy Metal Contamination
- Health Hazards: Causes neurological damage, kidney failure, bone deformities, cancers, and developmental disorders in children.
- Soil Degradation: Reduces soil fertility and microbial activity, lowering crop yield and food quality.
- Water Pollution: Contaminates rivers and groundwater, leading to bioaccumulation in fish and aquatic food chains.
- Economic Losses: Affects agriculture, fisheries, and increases healthcare costs in contaminated regions.
- Ecosystem Imbalance: Disrupts biodiversity, alters nutrient cycles, and damages flora and fauna in affected ecosystems.
Remedies for Heavy Metal Contamination
- Scientific and Technological Solutions: Eco-friendly reduction methods like adsorption, membrane filtration, and photocatalysis are being refined for sustainable water treatment.
- Bioremediation: Microorganisms and plants (e.g., Streptomyces Rochei) are used to absorb and detoxify metals from soil and water.
- Phytoremediation: Certain plants can extract metals from contaminated soil, offering a low-cost and green solution.
- Biosorption: It relies on the utilization of various types of raw materials derived from agro-waste, plant residue, and algal and microbial biomass.
- Reverse Osmosis: Water is passed through a series of semi- permeable filters.
- Resin based water treatment technology: It uses ion exchange resins — small, porous beads — to purify water by swapping undesirable ions for harmless ones.
- KC Valley Project: Karnataka’s treated wastewater recharge initiative helped restore groundwater quality in drought-prone areas.
- Community and Environmental Action:
- Decentralized water treatment: Emphasizes local solutions like sand filtration and activated carbon for rural communities.
- Land remediation: Steel slag and other industrial byproducts are being repurposed to reduce soil toxicity.
Government Initiatives
- National Clean Ganga Mission (NCG) and Namami Gange target industrial effluent reduction.
- National Aquifer Mapping & Management Programme (NAQUIM) identifies heavy-metal zones.
- Ban on leaded petrol (BS Norms) and lead paint regulations (2016).
- E-waste Management Rules (2022) to curb toxic discharges.
- National Programme on Prevention & Control of Fluorosis and Arsenicosis
