Groundwater Contamination in India | 05 Mar 2024

Source: DTE

Why in News?

The National Green Tribunal (NGT) recently expressed dissatisfaction over the Central Groundwater Authority's (CGWA) response to the widespread issue of toxic arsenic and fluoride in groundwater across India.

• Groundwater contamination due to arsenic is prevalent in 230 districts across 25 states of India while that caused due to fluoride is prevalent in 469 districts across 27 states.

What are the Sources of Groundwater Contamination?

• Naturally Occurring Contaminants: High levels of arsenic, fluoride, iron, and uranium exist naturally in some geological formations, contaminating groundwater.
  • In terms of arsenic and iron pollution, West Bengal and Assam are the worst affected states respectively.
• Agriculture: Excessive use of fertilisers, pesticides, and herbicides leach harmful chemicals into the water table.
• Industrial Waste: Untreated industrial effluents often find their way into groundwater sources, introducing heavy metals and other toxins.
• Urbanisation: Leaky sewage systems and improper waste disposal in urban areas contribute to groundwater pollution.
• Saltwater Intrusion: In coastal areas, over-pumping of groundwater can cause saltwater from the ocean to infiltrate freshwater aquifers, rendering the water unusable for drinking or irrigation.
  • Rajasthan has the highest number of rural habitations affected by (salinity) contamination.

What are the Primary Agents Responsible for Contaminating Groundwater?

• Arsenic: While arsenic occurs naturally, it is also present in human-made forms used in agriculture, mining, and manufacturing.
  • Seepage from industrial and mining discharges, as well as from fly ash ponds in thermal power plants, can introduce arsenic into groundwater.
  • Chronic exposure to arsenic can cause black foot disease.
• Fluoride: In India, fluorosis is a prevalent issue due to the consumption of water with high fluoride content.
  • Excessive fluoride intake can result in neuromuscular disorders, gastrointestinal problems, dental deformities, and skeletal fluorosis, characterised by painful and stiff joints.
  • Knock-knee syndrome, marked by outward bending of the legs from the knees, can also occur.
• Nitrates: Excessive nitrate levels in drinking water react with haemoglobin, forming non-functional methaemoglobin and hindering oxygen transport, leading to methemoglobinemia and blue baby syndrome.
  • High nitrate levels can also contribute to the formation of carcinogens and accelerate eutrophication.
    • Blue Baby Syndrome cause a bluish discolouration of the skin in babies, not just methemoglobinemia, due to excessive nitrate levels in drinking water.
    • Methemoglobinemia is a condition where an abnormal form of haemoglobin (methemoglobin) is present in the blood, reducing its ability to carry oxygen.
• Uranium: Uranium, weak radioactive with a long physical half-life, is found in concentrations above WHO guidelines in localised pockets in India.
  • In regions like Rajasthan and northwestern states, uranium is primarily present in alluvial aquifers, while in southern states like Telangana, it originates from crystalline rocks such as granite.
  • Elevated uranium levels in drinking water can cause kidney toxicity.
• Radon: Recently, in some areas of Bengaluru, groundwater used for drinking has been found to contain significantly high levels of radioactive radon.
  • Radon originates from radioactive granites and uranium, which undergoes decay to radium and radon.
  • The presence of radon in air and water can damage lung tissues, increasing the risk of lung cancer.
• Other Trace Metals: Water may also be contaminated by trace metals such as lead, mercury, cadmium, copper, chromium, and nickel, which possess carcinogenic properties.
  • Water contaminated with cadmium can cause Itai Itai disease, also called ouch-ouch disease.
  • Mercury in water causes Minamata (a neurological syndrome) in humans

Way Forward

• Strengthening Groundwater Regulation: Enforcing stricter regulations on industrial waste disposal and agricultural practices.
  • Implementing a permit system for groundwater extraction, with quotas based on aquifer recharge rates.
• Promoting Sustainable Agriculture: Provide subsidies and training for farmers to adopt precision agriculture techniques, careful utilisation of fertilizers, and efficient irrigation practices like drip irrigation.
• Investing in Infrastructure: Increasing investment in building and maintaining wastewater treatment plants to prevent untreated sewage from contaminating groundwater.
• Decentralised Management: Empowering local communities by fostering participatory water management models. This can involve forming Water User Associations (WUAs) for planning, monitoring, and regulating groundwater extraction in localized areas.
• Blue Credit: Offering financial incentives like Blue Credit for rainwater harvesting, greywater recycling, and adoption of water-saving technologies in domestic and industrial sectors.
• Utilising Artificial Intelligence (AI): Leveraging AI to analyse vast sets of data on water quality, usage patterns, and aquifer characteristics. This can help predict contamination risks and develop targeted interventions.