Why in News?
An assessment of India’s groundwater by the Central Ground Water Board (CGWB) found that several States are grappling with a serious problem of nitrate contamination.
- Concerns – The number of districts with excessive nitrate in their groundwater rose from 359 in 2017 to 440 in 2023.
- Nearly 56% of India’s districts having excessive nitrate in ground water, defined as having more than 45 mg/l (milligram per litre).
- Nitrogen in groundwater – Although nitrate is the main form in which nitrogen occurs in groundwater, dissolved nitrogen also occurs in the form of
- Ammonium (NH4+)
- Ammonia (NH3)
- Nitrite (NO2-)
- Nitrogen (N2)
- Nitrous oxide (N2O)
- Organic nitrogen.
- Vulnerable areas - Rajasthan, Karnataka and Tamil Nadu.
- Maharashtra, Telangana, Andhra Pradesh and Madhya Pradesh also show notable levels of nitrate contamination.
- Impact human health – It leads to methemoglobinemia, or a reduced ability of red blood cells to carry oxygen.
- Impact environment – Once the nitrates in the groundwater rise to the surface and become part of lakes & ponds, algal blooms emerge.
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Other Major chemical contaminants of Groundwater
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- Contaminants – Arsenic, iron, fluoride and uranium.
- Fluoride – It exceeds the permissible limit in Rajasthan, Haryana, Karnataka, Andhra Pradesh and Telangana.
- Uranium – It exceeds 100 ppb (parts per billion) in Rajasthan and Punjab.
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India’s degree of groundwater extraction is 60.4%, or roughly the same as it has been through the years since 2009. About 73% of the blocks are in the ‘safe’ zone, meaning that they are replenished enough to compensate for water drawn out.
Piezometers measure groundwater levels and transmit the information digitally to a centralised location.
Reference
The Hindu| Assessment of Groundwater Contamination in India
Related News – Groundwater Depletion in India
