Nitrogen Contamination in Groundwater

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.

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