NEWS & INFORMATION

Ground Water Quality and The total dissolved solids concentration The probable causes of ground water dete- varies from 165 mg/1 to 8540 mg/1, and rioration in National Capital Territory, Pollution Status in National about 21% of ground water samples violate Delhi are natural hydro-geological condi- Capital Territory, Delhi the permissible limit. The ground water of tions, overpopulation of Delhi, over exploi- Najafgarh, Kanjhawala and Alipur blocks tation of ground water, lack of rainfall har- Dr. B. Sengupta show higher concentration of total dis- vesting for recharge of ground water, im- solved solids. proper disposal of sewage and industrial Ground water plays an important role as an waste water, improper disposal of munici- The bacteriological studies indicate the essential and vital component of our life pal and industrial solid waste, and also lack presence of faecal coliform in 5.95% of the support system. The ground water re- of public awareness. samples, while total coliform is present in sources are being utilized for drinking, ir- 57.99% of ground water samples. Total coli- rigation and industrial purposes. With This article was provided courtesy of D. K. forms and faecal coliform are mostly pres- increasing demand for water in National Banerjee, PhD, Contributing Editor to Envi- ent in water drawn from hand pumps. In- Capital Territory, Delhi, there is exploita- ronmental Practice. adequate maintenance of hand pumps and tion pressure on ground water resources unhygienic conditions around the struc- Address correspondence to Dr. B. and growing concern of the deterioration ture may be responsible for this. The most Sengupta, Member Secretary, Central of ground water due to unplanned disposal affected blocks are City block, Shahadra Pollution Control Board, Parivesh Bhawan, of effluents, sewage and sewerage. block and Najafgarh block. EastArjun Nagar, Delhi no 032 INDIA; (fax) 91-11-221-7078 A collaborative study was conducted by The violation of trace metal limits has Central Pollution Control Board, Delhi been: chromium, lead and cadmium in along with Central Ground Water Board, 8.82%, 0.53% and 0.49% of ground water Delhi during February-March, 1998 to as- samples respectively, while the concentra- sess the ground water quality and its suit- tion of iron exceeds the limits in 33.33% ability for human consumption. An exten- samples. The concentration of copper and sive field survey was undertaken during zinc are found well below the prescribed which 303 ground water samples were col- limit. The violation of nickel limit could lected and analysed from different abstrac- not be assessed as no prescribed permissi- tion structures (hand pumps, tube wells, ble limit is available. The trace metal prob- dug wells, bore wells, etc.) representing var- lem is more observed in City and Najafg- ious depths and locations in Delhi. Ground arh blocks. water samples were analysed for physico- chemical parameters (including trace The presence of pesticides has been re- metals), bacteriological parameters, or- corded in a large number of ground water ganochlorine and organophosphorous pes- samples but their concentration is well be- ticides, total organic carbon, etc. The sa- low the prescribed World Health Organiza- lient findingso f the study are as follows. tion, 1996 permissible limits. Dieldrin and aldrin pesticides have violated permissible The ground water has significant nitrate limits in 12 and 3 ground water samples concentration ranging between 0.01 mg/1 respectively, while concentration of total to 1589 mg/1. About 63% samples have ni- BHC and total DDT are found to be well trate concentration below 45 mg/1, while within the limits. There are no guidelines 18.8% samples have nitrate exceeding the available for total endosulfan. prescribed Bureau of Indian Standards per- missible limit (ioomg/1). The most affected Based on overall impact of physico- blocks are Najafgarh, Kanjhawala and some chemical characteristics including heavy parts of City block. metals, about 45.5% ground water samples out of total 303 have been found unsuitable The fluoride concentration exceeds the Bu- for drinking, either due to nitrate, fluoride, reau of Indian Standards prescribed per- trace metals, total dissolved solids, or due missible limit (i.5mg/l) in 27.4% of ground to synergistic effects of some or all of these. water, and its concentration ranges be- The block wise sequence of overall deterio- tween 0.12 mg/1 to 12.52 mg/1. The most ration of ground water quality is Kanjha- affected areas include western and central wala block > Najafgarh block > City parts of Najafgarh block and north and block > Alipur block > Mehrauli block > southeast parts of Kanjhawala block. Shahadra block.

68 Environmental Practice 1 (2) June 1999

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