Nitrate toxicity high in new BBMP areas

Thirsty City:

Nitrate toxicity high  in new BBMP areas

 Map shows concentration of nitrate in Bangalore’s groundwater. Red spots show high level of nitrate due to sewage and solid waste leachate percolating into groundwater.

Water in many newly added areas of the Bruhat Bangalore Mahanagara Palike (BBMP) has high levels of nitrate. The phenomenon is attributed to heavy dependence on borewells coupled with lack of underground drainage system that has led to contamination of groundwater.

According to recent findings, water in Nayandahalli, South Layout and M S Road has 554 mg/L of nitrate content against the permissible limit of 45 mg/L.
Fluoride content in water is a natural phenomenon, but the presence of nitrate (NO3) is mainly man-made and prolonged consumption of contaminated water could lead to cancer.

High nitrate content in residential areas is primarily due to contamination caused by improper sanitation, leachate from animal waste, sewage seepage in the absence of underground drainage system, reckless dumping of solid waste and rampant use of fertilisers and manure, according to a study conducted by the Department of Mines and Geology (DMG) to assess quality of groundwater.

As per the findings of the DMG, areas which have recorded high concentration of nitrate in Bangalore City are K R Puram, Ramamurthy Nagar, Mahadevapura, Varthur, Bommanahalli, Anjanapura, Rajajeshwari Nagar, Nayandahalli, Dasarahalli, Herohalli, Byatarayanapura, Kempegowda Nagar, Thanisandra, Lakshmidevi Nagar in West and Vishwanathanagenahalli in East.

Poor sanitation

Most of these areas lack proper sanitation system. A majority of the residents here dig soak pit either in their backyard or in front of their houses for sewage water to flow. Also, the residents dump solid waste on the roads or at places close to borewells. Sewage from soak pits and leachate from solid waste that are rich in nitrates percolate into groundwater contaminating borewells.

Department of Mines and Geology chief chemist M V Shashirekha said the people are unaware of the harmful effects of nitrate, as its presence in water does not change either its taste or odour.

“Use of animal dung as manure — especially horse dung and sheep excrement — contributes to 90 per cent of nitrate in groundwater. Whereas, solid waste leachate adds up to 50-60 per cent and sewage water adds nearly 25 per cent of nitrate to groundwater,” she said.

Boiling increases nitrate level

M V Shashirekha, chief chemist, the Department of Mines and Geology, said people who thought boiling water protected them from contamination should beware of boiling water with nitrate content, because that actually increased the nitrate content.

Nitrate causes infant methemoglobinemia (blue baby syndrome) and very high concentrations can lead to gastric cancer and adversely affect the central nervous and cardiovascular system.

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