Current World Environment

Introduction

Delhi, situated at the bank of Yamuna river, between the latitudes 280 12' -280 53' N and the longitudes 760 50'- 770 23', is one of the important business centers of India and thickly populated as well¹. Average water consumption in Delhi is estimated at being 240 liters per capita per day (lpcd), the highest in the country². This demand for drinking water is supplied by the Delhi Jal Board and is wholly provided or partially substituted by the available ground water of the area. Although the water supplied is normally tested for its suitability for drinking, ground water is accepted as such by the residents without an investigation of its potential for usage.

Any foreign matter contaminates water, which may be either natural or artificial. Inorganic materials, such as acids, salts, nitrates and chlorides that normally are not toxic at low concentrations may become concentrated enough to lower water quality or adversely affect biological communities³. Potential sources of contamination of water during pumping include leachates and corrosion products from pipe materials, pipe linings and organic substances able to permeate through plastic pipe materials laid after boring⁴. The underground water is also threatened with pollution from seepage pits, refuse dumps, septic tanks, barnyard manures, transport accidents, and with diverse agricultural, chemical or biological pollutants⁵.

In this study, attempt has been made to investigate the quality of water at 4 locations in Delhi to determine its quality. These locations have been selected randomly.

Material and Methods

Standard methods of collection, preservation and analysis were adopted (6). Grab sampling method was used for the collection of 4 Ground water samples used for drinking from the city (Figure 1). The analysis of Physio chemical parameters was done by procedure adopted from Standard Methods: APHA (6) and the elemental analysis were done using ICPMS (Inductively Coupled Plasma Mass Spectrometer, PERKIN ELMER, Elan DRCe).
 

Figure 1: Map of Delhi depicting location of Sampling Sites Click here to view table

Results and Discussion

Sample 1, Groundwater from Badarpur

All the Physio chemical parameters were within the permissible range by IS 10500 standards. Similarly elemental parameters depicted conformity with the IS 10500 prescribed standards. The water can therefore be used for drinking purposes after chlorination.

Sample 2, Groundwater from Nangloi

The pH of the water sample collected from Nangloi was 7.41.The water sample collected from Nangloi depicted on analysis all Physico-chemical parameters to be under the IS 10500 prescribed limit for drinking purposes with the exception of nitrate, hardness and fluoride. They are found to exceed the IS prescribed limit of 100 ppm, 600 ppm and 1 ppm respectively.

A high level of hardness indicates the presence of salts in water and thereby changes its palatability, consequently reducing its acceptability for drinking. A high level of hardness (above 300 ppm) also leads to scale formation in water supply structures and boilers (7), whereas ver y low hardness in water can lead to corrosion of pipelines (8). A high concentration of hardness may be due to leaching of minerals from the soils (9).

Conversely the elemental characteristics for all the parameters considered were found to be under the guidelines prescribed by IS for drinking. This water could be therefore considered safe for drinking purposes after treatment for Nitrate, Hardness and fluoride.

Sample 3, Groundwater from Pitampura

The pH of the water sample collected from Pitampura was slightly alkaline (8.04).The water sample collected from Nangloi depicted on analysis all Physico-chemical parameters to be under the IS 10500 prescribed limit for drinking purposes with the exception of fluoride. The level of fluoride was found to be highest among all the samples tested and was found to exceed the IS prescribed limit of 1 ppm.

Fluoride combines with the hydrochloric acid of stomach and leads to the formation of hydrogen fluoride which is highly corrosive (9). Fluoride is released into the ground water through weathering of primary silicates and associated accessory minerals (10).

The elemental characteristics depicted conformity with the IS standards with the exception of selenium (20.59 ppb) and calcium (215.17 ppm). They exceeded the prescribed standards of 10 ppb and 200 ppm respectively.

Sample 4, Groundwater from Sarai Rohilla

The water sample collected from Sarai Rohilla depicted on analysis an elevated concentration of nitrate (193.2 ppm), highest among all samples tested. All other Physico-chemical parameters were found to be under the IS 10500 prescribed limit for drinking purposes. Nitrate has long been associated with the occurrence of blue baby disease in infants or infantile methaemoglobinaemia which is caused due to bacterial reduction of nitrate into nitrite in stomach (11). Such high concentration of nitrate in drinking water may be attributed to the leaching of products of organic material biodegradation into the water sources.

Conversely, the elemental analysis depicted an elevated concentration of selenium. Selenium is an element needed by humans and other animals in small amounts, but in larger amounts can cause damage to the nervous system, fatigue, and irritability (2). This water therefore requires treatment.
 

Table 1: List of the methods used for Physico-chemical analysis and the instruments used for elemental analysis. Click here to view table

Table 2: Values for physio chemical parameters estimated by chemical analysis Click here to view table

Table 3: Values for elemental parameters estimated by Atomic Absorption Spectrophotometer and Inductively Coupled Plasma Mass Specrometer. Click here to view table

Acknowledgements

The analysis was carried out in ARBRO Analytical Division, New Delhi.

References

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2. Goel P. K, Water pollution Causes, Effects and Control, Second Edition, New Age International, New Delhi,(2006) 132-134.
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