The most serious pollution threat to groundwater was from calcium, chloride and iron, associated with sewage and pollution from tannery waste
Groundwater is becoming more polluted in Tamil Nadu’s industrial areas and Vellore is the state’s most polluted district in terms of river pollution, according to a new study by Delhi-based thinktank, Centre for Science and Environment (CSE).
CSE did an assessment of Tamil Nadu CEPI scores. CEPI (Comprehensive Environmental Pollution Index) is a rational number to characterise the quality of the environment at a given location following the algorithm of source, pathway and receptor. An increase in CEPI score denotes adverse effects on the receiving environment.
Five industrial clusters in Tamil Nadu were found to have a water score of more than 50. Three of these — Vellore-North Arcot, Manali and Tiruppur — were ‘critically polluted’ and two — Cuddalore and Coimbatore — were ‘severely polluted’, according to the CEPI water score 2018.
A CEPI individual score of 60 and above denotes an industrial area to be a ‘critically polluted area’ and a score between 50-60 denotes it to be a ‘severely polluted area’.
The CEPI water score of Vellore-North Arcot was 65.25 in 2009. This increased to 75 in 2018. Manali had a CEPI water score of 59 in 2009, which increased to 72.25 in 2018. Tiruppur had a CEPI water score of 50.75 in 2009, which increased to 65 in 2018.
Vellore, the most polluted district in Tamil Nadu in terms of river pollution, was home to 240 tanneries, 17 red category industries and small-scale chemical industries, according to CSE.
Partially treated industrial effluents, combined with sewage and other wastes were being discharged directly into surface water according to the study, Assessment of groundwater quality in some towns of Vellore district, Tamil Nadu, India.
This had caused severe groundwater pollution in the industrial belt. The most serious pollution threat to groundwater was from calcium, chloride and iron, that are associated with sewage and pollution from tannery waste.
Critically and severely water polluted industrial clusters in Tamil Nadu CEPI 2018 surface water score
|No.||Name of Polluted Industrial Areas (PIAs)||Water||
|1||Vellore -North Arcot||75.00||Critically Polluted|
CSE also found that five industrial clusters in Tamil Nadu had a land score of more than 50. For arriving at land score, ground water and soil quality was considered.
Four of the five clusters — Manali, Mettur, Tiruppur and Tuticorin — fell under the ‘critically polluted’ category and one industrial cluster (Erode) fell under the ‘severely polluted’ category with respect to groundwater and soil pollution.
The land score of the Manali industrial cluster was 58 in 2009. This increased to 71.75 in 2018. Tiruppur had a CEPI land score of 53 in 2009, which increased to 64 in 2018. Mettur had a land CEPI score of 46.5 in 2009, which increased to 69.38 in 2018. Erode had a CEPI score 43.5 in 2009, which increased to 52.75 in 2018.
Critically and severely land polluted industrial clusters in Tamil Nadu CEPI 2018 (Groundwater and soil score)
|S.No||Name of Polluted Industrial Areas (PIAs)||Land Score||Category|
The Manali industrial area was one of the most polluted areas identiﬁed by the Central Pollution Control Board (CPCB). About 300 industries had come up in this area, including chemicals, plastics, petrochemicals, refineries and fertilisers.
Some well-known industries like Madras Fertilizers Ltd, Madras Petrochemicals Ltd and Madras Reﬁneries Ltd had also ﬂourished in the area during recent years.
The study Assessment of heavy metal contamination in soils around Manali industrial area showed heavy metal pollution in the area and found elevated concentrations of chromium (149.8–418.0 mg / kg), copper (22.4–372.0 mg / kg), nickel (11.8–78.8 mg / kg), zinc (63.5–213.6 mg / kg) and molybdenum (2.3–15.3mg / kg), that had resulted in ground water and pollution.
Manali was extremely contaminated due to several years of random dumping of hazardous waste and free discharge of efﬂuents on land by industries. The high amount of toxic metals in the environment might have also caused an increase in their presence in groundwater as a result of leaching.
CEPI was a tool developed by the CPCB in 2009 to identify the problematic industrial areas in the country. In 2009, 88 industrial clusters were notified as polluted industrial areas.
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