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Context:

According to the Lancet Public Health analysis Lead exposure causes $6 trillion in economic losses from premature death due to cardiovascular disease and cognitive dysfunction.

What is Heavy Metal Pollution?

Heavy metals are naturally occurring elements in the Earth’s crust since its formation. These metals may be defined as elements with an atomic number larger than 20 and an atomic density greater than 5 g cm3 that must possess metal-like characteristics. For e.g. arsenic, cadmium, chromium, copper, lead, manganese, mercury, nickel, uranium etc.

Heavy metal pollution is a global issue that occurs when heavy metals are released into the environment at levels that are harmful to humans and the environment. These are well-known environmental pollutants owing to their toxicity, longevity in the atmosphere, and ability to accumulate in the human body via bioaccumulation. The pollution of terrestrial and aquatic ecosystems with toxic heavy metals is a major environmental concern that has consequences for public health.

What are the Sources of Heavy Metals?

Sources of heavy metals include mining, industrial production (foundries, smelters, oil refineries, petrochemical plants, pesticide production, chemical industry), untreated sewage sludge and diffuse sources such as metal piping, traffic and combustion by-products from coal-burning power stations.

The effects on human health and the environment

• Mercury exposure can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. In babies and young children, the nervous system can be affected making the child less able to think and learn.
• Mercury accumulation in fish may harm the fish and other animals that consume them. Birds and mammals that eat fish are more exposed to mercury than other animals which live in aquatic ecosystems.
• Lead may, according to UNEP cause neurodevelopmental effects in children, even at low levels of exposure. Other effects include cardiovascular, renal, gastrointestinal, hematological and reproductive effects.
• In the environment, lead bioaccumulates in most organisms and is toxic to plants, animals and micro-organisms. Young fish are more susceptible to lead poisoning than mature fish or eggs. 
• Cadmium is toxic to humans and exposure can cause pulmonary irritation, kidney disease, bone weakness and possibly lung, prostate, and kidney cancer. Food and cigarette smoke are the largest potential sources of cadmium exposure for the general population.
• Cadmium is also toxic to plants, animals and micro-organisms. Cadmium accumulates mainly in the kidney and liver of vertebrates and in aquatic invertebrates and algae. 

Efforts to Monitor Heavy Metal Pollution

Total Monitoring Stations	764 river quality monitoring stations across 28 states.
Ganga Monitoring Stations	33 monitoring stations in Ganga; 10 stations had high levels of heavy metal contaminants.
Heavy Metals Testing	Central Water Commission examined water samples from 688 sites for heavy metals between August 2018 and December 2020.

Statistics

Pollution Indicators	High total coliform levels in 239 stations and high biochemical oxygen demand in 88 out of 588 stations examined across 21 states.
Wastewater Treatment	Indicates inadequate wastewater treatment from industrial, agricultural, and domestic sources.
Key Findings (CSE Report 2022)	River Ganga, targeted under the Namami Gange mission, has high levels of lead, iron, nickel, cadmium, and arsenic.
Sewage Treatment (CPCB Findings)	Ten states do not treat their sewage at all.
Untreated Sewage	72% of sewage waste in India is dumped untreated.

Consequences

Heavy metal poisoning can lead to many health complications, such as liver and renal dysfunction, dermatological difficulties, and potentially even malignancies. To mitigate the risk of heavy metal ion exposure to humans and animals, it is imperative to extract them from places that have been polluted.

Methods

Several conventional methods such as ion exchange, reverse osmosis, ultrafiltration, membrane filtration and chemical precipitation have been used for the removal of heavy metal ions.

Way forward

1. The development and implementation of a comprehensive water resources plan, policy formulation, coordination, and guidance.
2. Irrigation, flood control, and multi-purpose projects need to be closely monitored, supervised, inspected, cleaned, and monitored for their effectiveness.
3. Groundwater development is the process of developing groundwater resources, establishing utilizable resources, and formulating policies for their exploitation, along with the supervision of state-level groundwater development activities and the support that is provided to them.
4. The development of a comprehensive perspective regarding the water resources of a nation and the assessment of the water balance across various basins and sub-basins are key considerations in the evaluation of inter-basin transfer feasibility.

Conclusion

Heavy metal ions can cause severe health problems. To prevent the harmful effects of these toxic metals, it is important to find an eco-friendly and cost-effective method to remove heavy metal ions contamination from wastewater. Biosorption is an eco-friendly method based on the biomass derived from plant, algal, and agricultural waste and microbes. This method is environmentally friendly and does not require much investment. This review provides basic to advanced knowledge to the research about heavy metal contamination and their eco-friendly removal process.

READ ABOUT

CWC Report on Toxic Heavy Metals in Rivers

groundwater contamination in india

REFERENCE

https://pubs.acs.org/doi/abs/10.1021/bk-2023-1456.ch001

https://www.unep.org/cep/heavy-metals

https://link.springer.com/referenceworkentry/10.1007/978-3-030-45009-0_96

https://www.intechopen.com/chapters/74985

https://pubmed.ncbi.nlm.nih.gov/38556536

https://www.nature.com/articles/s41598-024-58061-3

Source:

DOWNTOEARTH

PRACTICE QUESTION Q.Heavy metal pollution is one of the critical environmental challenges of the modern industrial era. Discuss the sources, impacts, and measures that can be adopted to mitigate heavy metal pollution in India. Evaluate the role of regulatory frameworks and public awareness in addressing this issue. (250 words)