INTRODUCTION:

A water resource (rain, river, and Ground water) is one of the major components of environmental resources that are under threat either from over exploitation or pollution¹. The lack of safe drinking water and inadequate sanitation measures lead to a number of diseases such as cholera, dysentery, typhoid and every year millions of lives are claimed in the developing countries². The evaluation of potable water supplies for coli form bacteria is important in determining the sanitary quality of drinking water. The coli form group of bacteria can be defined as principal indicators of purity of water for domestic, industrial and other uses. High levels of coli form counts indicate a contaminated source, inadequate treatment or post-treatment deficiencies³. It has been reported that drinking water supplies have a long history of association with a wide spectrum of microbial infections⁴. Therefore, the primary goal of water quality management from a health perspective is to ensure that consumers are not exposed to doses of pathogens that are likely to cause disease^5-7.

Major factors affecting the microbiological quality of surface water are discharges from sewage works and runoff from informal settlements. Many developing regions suffer from either chronic shortages of fresh water or readily accessible water resources are heavily polluted⁸. Internal factors on the other hand include events which occur between and within bacterial and plankton population in the water body^9-10.

Navi Mumbai is a twin of Mumbai city. It is a part of south coast line. This coastal line joins Sahyadri Mountain ranges in the south and 50 to 100m hills in East. Navi Mumbai is located between 19⁰5’ to 19⁰15’ Latitude and 72⁰55’ to 73⁰5’ Longitude. The population in this area is more than 8 lacs. Thane-Belapur Industrial area has been broadly classified into two major zones–Chemical Zone and Electronic Zone. Taking into consideration the magnitude and variety of industries and residential complexes nearby, this area provides an important opportunity to understand the load and impact of pollution arising due to various sources industrial and domestic. Thus there is a need for basic monitoring on water quality to observe the demand and pollution level of ground water¹¹.

Naturally, these ground water resources such as wells, hand pump, bore well, etc. alongside these nullahs are subjected to a damage of the water quality due to percolation or seepage from the nullah. Physico-chemical and Microbiological analysis was done monthly for the Ground water samples of the different sites which cover the areas of mainly the engineering industries and the chemical industries nearby.

EXPERIMENTAL:

All the samples were collected in three litre capacity polythene bottle having double stopper. Prior to the collection, the well cleaned sample bottles were rinsed thoroughly with the sample water to be collected. After collecting the samples, the bottles were immediately closed tightly. In case of open wells, the samples were collected from a depth of about one meter from the upper surface of water. Each sample bottle was clearly labeled with a glass marker and relevant details were recorded. All sample bottles were sealed and brought to the laboratory as soon as possible after protecting them from direct sunlight during transportation the samples so collected were kept at a low temperature in the dark. Samples were collected from wells in and around the area of investigation for monthly interval from December 2004 to November 2005. All the water samples were analyzed within 12 to 24 hr after collection.

The physico-chemical and microbiological analysis of ground water samples were carried by instrumental and non-instrumental method. Temperature and pH were determined by using Water Analysis Kit (century make). Turbidity by nephlometer, total plate count and E- coli by incubating 0.1ml diluted sample (10^-2- 10^-4 times) in typtose glucose agar medium and Cosin-methylene blue- agar medium at 35-37^oC + 0.5^oc, 1^oc for 38 and 48 hours respectively for total plate count and E- coli. The most probable numbers of coliform were carried with five tube method with Macconkay broth.

RESULTS AND DISCUSSION:

The Physico-chemical and microbiological study reveals that physical parameters such as pH, temperature and turbidity have a major influence on bacterial population growth¹². According to Kunte et.al¹³, pH ranging from 3 to 10.5 favors both indicator and pathogenic Microorganism growth. pH value during the present study showed fluctuation. The maximum pH values were recorded at Nocil tanker site and the minimum at Koparkhaine site (Fig. 1). The higher pH value may be attributed to the photosynthetic activity and lower pH value to the increased temperature which enhances the microbial activity causing excessive production of CO_2.

Temperature is basically important for its effect on chemistry and biological relations in the organisms living in water¹⁴. A rise in temperature of water leads to the speeding up of the chemical reactions in water reduces the solubility of gases and amplifies the tastes and odours¹⁵. The minimum temperature was recorded in winter and maximum in summer (Fig. 2). In the present study minimum temperature was recorded at Airoli site and maximum at Rabale site in the month of December and May respectively.

Turbidity values during he present investigation varied with seasonal changes. Maximum turbidity observed in monsoon and minimum during summer. The maximum turbidity value may be attributed to higher microbial load which increases coliforms and which are also responsible in spreading water-borne disease. Maximum turbidity was observed at Rabale site and minimum at Koparkhairne site (Fig. 3). The values of turbidity during findings varied from 0.30 to 21.00 NTU. The turbidity measured in these sites was far above the standard limits according to WHO Standards.

In the present investigation Total plate count varied from 110 to 2500 cfu/ml which is beyond Permissible limit for drinking water. The maximum peak is recorded in monsoon may be attributed to the intervening events such as heavy rainfall, failed sewage system, contamination through back siphonage, chemicals spill run off water may lead to contamination of water. The minimum peak may be attributed to increase in sewage dumping in the Sampling sink areas leading to increase in toxicity which also enhances Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD)values. The minimum value recorded in winter may be attributed to low temperature which retards the growth of micro-organisms especially that of coliform. The findings of the present investigation reveals that the maximum bacterial population in open wells than covered wells, which may be attributed toe the exposure of open wells to contamination of dust, droplets, microbial spores etc (Fig. 4). Our findings are in good agreement with the work reported by Udhayan Kumar¹⁶. The study showed that human and animal activities at the water collection sites affected the quality of water. Anthropological and animal activities in the vicinity of water collection sites as well as settlements lacking proper sanitation facilities, contributed to poor quality of water at different sampling sites¹⁷.

The Most Probable Number index of all the water samples was greater than 2400 indicating the faecal contamination of water. Most of the water samples contain significant amount of organic matter that provides nutrition for the growth and multiplication of micro organisms. E-coli were detected in the series of sample collected over a protected period of time indicating the faecal contamination of water and public health hazards, these results are also supported by the Most Probable Number test indicating >2400 coliform per hundred ml. The water is therefore not recommended for use without prior treatment^18,19. The high coliform count may be an indication that water sources are feacally contaminated.

CONCLUSION:

The findings of the present investigation reveal that to ground water samples of all study Area is unfit for human consumption. The water quality parameters of concern were Microbial contamination and turbidity. The poor quality of water may be attributed to the presence of high numbers of indicator micro-organisms. Therefore, there is need for the protection of domestic water sources, and it should be supported by strong environmental awareness campaign to help the people to participate positively in efforts to protect the quality of their water resources.

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Received on 16.09.2009 Modified on 13.11.2009

Asian J. Research Chem. 3(1): Jan.-Mar. 2010; Page 102-105