CHENNAI: Groundwater in five districts of Tamil Nadu is contaminated by heavy metals like lead, cadmium and chromium which are beyond the permissible limits of Bureau of Indian Standards (BIS), a study by the Central Groundwater Board has revealed.
The board which regularly monitors groundwater quality of shallow aquifers on a regional scale, once a year, has found that groundwater in Dindigul, Tiruvallur and Kancheepuram contains lead above 0.01mg per litre. Dindigul has more than 80 tannery units in and around the city and also possesses chromium above 0.05mg per litre which is above the BIS limit. Interestingly, CGWB states that groundwater in Cuddalore, Erode, Kancheepuram and Tiruvallur districts is also contaminated by chromium.
Chromium is used in the manufacture of alloys, inhibitory paints, wood preservatives, fixatives for dyes and tanning, photographic sensitisers and as anticorrosive in cooking systems and boilers. Chromium contamination usually occurs via poor storage, leakage or incorrect disposal methods.
Interestingly, the study also points out that groundwater in Tiruvallur district is contaminated by cadmium. This means the groundwater in two neighbouring districts of Chennai is contaminated by heavy metals like lead, cadmium and chromium and is not potable.
When Express contacted State government officials for their reaction to heavy metal polluting groundwater resources, they said that they don’t monitor the heavy metal values in water as they don’t have the equipment. “We had the equipment in 1995, but then they became old. Now, we are procuring new equipment and these will be in place in the next couple of months,” a State source said.
Besides heavy metal pollution, groundwater in 23 districts of Tamil Nadu has levels of salinity above the prescribed BIS limits. Similarly, fluoride levels in groundwater is above the BIS prescribed limits of 1.5 mg per litre in 19 districts.
Similarly, arsenic pollution of groundwater is reported in nine districts which has it above 0.01mg/l. Even nitrate pollution is reported in 27 districts of the State. According to statistics of Niti Aayog report, 600 million Indians face high to extreme water stress.
Districts close to chennai affected
Interestingly, the study also points out that groundwater in Tiruvallur district is contaminated by cadmium. This means the groundwater in two neighbouring districts of Chennai is contaminated
Heavy metal pollution of groundwater in districts:
Lead: Dindigul, Tiruvallur, Kancheepuram
Chromium: Cuddalore, Dindigul, Erode, Kancheepuram, Tiruvallur