Marked deterioration noticed in quality of shallow groundwater
CHENNAI: The magnitude of groundwater pollution due to indiscriminate discharge of solid and liquid waste by the industry and fertilizers/pesticides used excessively by farmers have reached an “alarming stage” in the State, according to a paper presented at a recent workshop organised by the Central Groundwater Board.
The affected areas include Dindigul, Ranipet-Ambur-Vaniyambadi-Pernambut in Vellore district; Sembattu in Tiruchi district and parts of Erode district and Chromepet near Chennai (known for the presence of tannery units); Tiruppur (knitwear and hosiery); parts of Karur and Erode districts (textile and weaving units); and parts of Salem and Namakkal (tapioca processing units).
While aquaculture has been cited as the reason for the pollution in coastal tracts of Nagapattinam district, the presence of engineering industries at Ambattur near Chennai and Coimbatore city and surrounding areas is said to have caused the pollution. The Manali industrial area in Tiruvallur district, where petrochemical units and refineries are located, is another affected area the paper said.
Submitted by scientist at the CGWB K. Ravichandran, the paper stated that special studies carried out by the Board in and around tannery belts between 2002 and 2008 revealed that an undesirable change in physical and chemical characteristics of soil and groundwater had been noticed, rendering thousands of hectares of fertile land sterile. In other areas, the study began in the year 2000.
A study of analytical results of groundwater quality tested by the Board and the State government’s agencies showed that the quality of shallow groundwater, in general, had deteriorated much. The concentration of dissolved solids and chlorides in water samples collected from dug wells was extremely high, ranging between 20,000 milligram per litre and 35,000 mg/l, especially in the tannery belts.
Studies in Dindigul indicated that the common effluent treatment plant had not been effective in reducing total dissolved solids to permissible limit for domestic use. Describing the Ranipet region as an “endangered area,” the paper called for strong measures from the government to arrest the deterioration. Groundwater in Chromepet was highly mineralised and excessively hard. In Manali, toxic heavy metals were present in the industrial effluents and surface water sources.