India faces groundwater contamination crisis as of 2023. A report by the Central Groundwater Board marks that 440 districts have excessive nitrates in their groundwater. This figure has risen from 359 districts in 2017. The health risks associated with high nitrate levels are particularly concerning for young children. The report indicates that 56% of India’s districts exceed the safe limit of 45 mg per litre for nitrates.
Sources of Nitrate Contamination
The primary cause of nitrate contamination is the extensive use of subsidised nitrogenous fertilisers in agriculture. These fertilisers are crucial for crop production but contribute to the leaching of nitrates into groundwater. Approximately 19.8% of 15,239 groundwater samples collected across India contained nitrates above safe levels. This percentage has remained relatively stable since 2017.
Regional Analysis of Nitrate Levels
Certain regions are more affected by nitrate contamination. Rajasthan leads with 49% of samples exceeding safe limits, followed by Karnataka at 48% and Tamil Nadu at 37%. Central and southern states, including Maharashtra and Telangana, are also experiencing increasing nitrate levels. The report shows a worrying trend in these areas, which could escalate health risks.
Impact of Monsoon Rainfall
Monsoon rainfall influences nitrate levels in groundwater. Contamination levels rise from 30.77% in the pre-monsoon period to 32.66% post-monsoon. This increase suggests that rainfall may exacerbate the leaching process of nitrates into groundwater.
Other Contaminants – Fluoride and Uranium
In addition to nitrates, fluoride and uranium are major contaminants affecting groundwater quality. Rajasthan, Haryana, Karnataka, Andhra Pradesh, and Telangana report high fluoride concentrations. Uranium levels exceeding 30 ppb are found in regions like Rajasthan and Punjab. These contaminants pose serious health risks, particularly where groundwater is over-exploited.
Groundwater Extraction Trends
The overall groundwater extraction rate in India stands at 60.4%. This rate has remained constant since 2009. About 73% of the blocks analysed for groundwater levels are classified as ‘safe,’ indicating sufficient replenishment. However, the number of blocks analysed has decreased, raising concerns about the reliability of these assessments.
Government Response and Future Actions
The Jal Shakti Ministry is aware of the growing nitrate contamination issue. Immediate steps are required to address this public health hazard. Solutions may include regulating fertiliser use, improving groundwater management, and enhancing monitoring systems.
Questions for UPSC:
- Examine the impact of excessive nitrate levels on public health in India.
- What are the primary causes of groundwater contamination in India? Discuss with suitable examples.
- Critically discuss the role of monsoon rainfall in altering groundwater quality.
- Discuss in the light of recent data, the implications of groundwater over-extraction on environmental sustainability.
Answer Hints:
1. Examine the impact of excessive nitrate levels on public health in India.
- High nitrate levels in drinking water can lead to methemoglobinemia, or “blue baby syndrome,” particularly affecting infants.
- Long-term exposure to nitrates may increase the risk of certain cancers and other chronic health conditions.
- Children are particularly vulnerable due to their developing systems, leading to potential cognitive and developmental issues.
- Excessive nitrates can also cause gastrointestinal problems and other acute health issues in all age groups.
- The economic burden on healthcare systems increases due to nitrate-related health complications, straining public resources.
2. What are the primary causes of groundwater contamination in India? Discuss with suitable examples.
- The extensive use of subsidised nitrogenous fertilizers in agriculture is the main contributor to nitrate contamination.
- Improper waste disposal and industrial discharge lead to chemical pollutants infiltrating groundwater supplies.
- Over-exploitation of groundwater resources results in concentration of contaminants, as less water dilutes harmful substances.
- Urbanization and inadequate sewage treatment facilities exacerbate contamination issues in densely populated areas.
- Examples include Rajasthan and Punjab, where high levels of uranium and fluoride have been reported due to mining and agricultural runoff.
3. Critically discuss the role of monsoon rainfall in altering groundwater quality.
- Monsoon rains increase surface runoff, which can wash fertilizers and contaminants into groundwater sources.
- Post-monsoon periods show a rise in nitrate contamination levels, indicating that rainfall exacerbates leaching processes.
- Higher water levels can dilute contaminants but may also lead to increased infiltration of polluted water into aquifers.
- Rainfall patterns influence the timing and intensity of contamination, with varying effects across regions in India.
- Effective rainfall management strategies are needed to mitigate the negative impacts on groundwater quality.
4. Discuss in the light of recent data, the implications of groundwater over-extraction on environmental sustainability.
- Groundwater over-extraction leads to depletion of aquifers, compromising water availability for future generations.
- It increases the concentration of pollutants, such as nitrates and heavy metals, in remaining groundwater supplies.
- Over-extraction can result in land subsidence and reduced soil quality, impacting agricultural productivity.
- Environmental sustainability is threatened as ecosystems dependent on groundwater are adversely affected.
- Recent data indicates that 60.4% of groundwater is extracted, with only 73% of blocks classified as safe, denoting the urgent need for sustainable practices.
