Assessment of heavy metal and bacterial pollution in coastal aquifers from SIPCOT industrial zones, Gulf of Mannar, South Coast of Tamil Nadu, India
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Heavy metals and microbiological contamination were investigated in groundwater in the industrial and coastal city of Thoothukudi. The main sources of drinking water in this area are water bores which are dug up to the depth of 10–50 m in almost every house. A number of chemical and pharmaceutical industries have been established since past three decades. Effluents from these industries are reportedly being directly discharged onto surrounding land, irrigation fields and surface water bodies forming point and non-point sources of contamination for groundwater in the study area. The study consists of the determination of physico-chemical properties, trace metals, heavy metals and microbiological quality of drinking water. Heavy metals were analysed using Inductively Coupled Plasma Mass Spectrometry and compared with the (WHO in Guidelines for drinking water quality, 2004) standards. The organic contamination was detected in terms of most probable number (MPN) test in order to find out faecal coliforms that were identified through biochemical tests. A comparison of the results of groundwater samples with WHO guidelines reveals that most of the groundwater samples are heavily contaminated with heavy metals like arsenic, selenium, lead, boron, aluminium, iron and vanadium. The selenium level was higher than 0.01 mg/l in 82 % of the study area and the arsenic concentration exceeded 0.01 mg/l in 42 % of the area. The results reveal that heavy metal contamination in the area is mainly due to the discharge of effluents from copper industries, alkali chemical industry, fertiliser industry, thermal power plant and sea food industries. The results showed that there are pollutions for the groundwater, and the total Coliform means values ranged from 0.6–145 MPN ml−1, faecal Coliform ranged from 2.2–143 MPN ml−1, Escherichia coli ranged from 0.9 to 40 MPN ml−1 and faecal streptococci ranged from 10–9.20 × 102 CFU ml−1. The coastal regions are highly contaminated with total coliform bacteria, faecal coliform bacteria and E. coli. This might be due to the mixing of sewage from Thoothukudi town through the Buckle channel and fishing activity.
KeywordsGroundwater ICP-MS Heavy metals MPN WHO Thoothukudi
Groundwater is one of the most vital resources for the sustenance of humans, plants and other living beings. It is required in all aspects of life for producing food for agricultural activities and for energy generation. Groundwater is rarely treated presuming being a naturally protected source. It is considered to be free from impurities, which are associated with surface water, because it comes from deeper parts of the earth. Increasing population and rapid urbanization has lead to several environmental problems including groundwater pollution.
The accumulation of Trace metals in groundwater has direct consequences to both man and the ecosystem. There are two main sources of heavy metals in groundwater (i) natural (ii) anthropogenic sources. The natural sources include the release of metals from rock weathering and their final leaching into groundwater by rock water interaction. The anthropogenic sources include discharge of heavy metals into the atmosphere by burning of fossil fuels/industrial activities and, thereby, to the streams by rain and also through discharge of industrial effluents and sewage water into streams and surface water bodies (Antony Ravindran and Selvam 2014; Dutka and Bell 1973; Handa 1981; Leung and Jiao 2006; Selvam and Sivasubramanian 2012a; Singaraja et al. 2015).
Drinking water is a major source of microbial pathogens in developing regions, although poor sanitation and food sources are integral to enteric pathogen exposure (Macler and Merkel 2000; Lerner and Harris 2009). The lack of safe drinking water and adequate sanitation measures lead to a number of diseases such as cholera, dysentery, salmonellosis and typhoid, and every year millions of lives are claimed in developing countries (Van Ryneveld and Fourie 1997). Groundwater is the main source of drinking water in the villages without any treatment. It may be contaminated by disease-producing pathogens, leachate from landfills and septic systems, careless disposal of hazardous household products, agricultural chemicals and leaking underground storage tanks.
Interest in metals like zinc (Zn) and copper (Cu), which are required for metabolic activity in organisms, lies in the narrow “window” between their essentiality and toxicity. Others like aluminium (Al), cadmium (Cd) and lead (Pb) exhibit extreme toxicity even at trace levels (Vanloon and Duffy 2005; Puthiyasekar et al. 2010). The quality of water has now become an important topic in all the countries, especially with respect to drinking water. Although water plays an essential role in human life, it has a great potential for transmitting a wide variety of diseases and illnesses. Contaminated water-related conditions result in cholera, dysentery, typhoid fever, ring worms, skin irritation and any other illnesses associated with the consumption and use of poor water supplies.
Heavy metals are major toxic pollutants that severely limit the beneficial use of water for domestic or industrial applications (Nouri et al. 2006). Groundwater pollution over the years, due to contaminant leaking from the disposal sites, is a big problem in many countries. Industries such as ceramic, painting, glass, mining and battery manufacturing are considered the main sources of heavy metals in local water streams and it eventually contaminates the groundwater with heavy metals. Land fill leachate site is another source of heavy metal contamination in groundwater (Sang et al. 2008). Increase in human activities such as industrialization coupled with over population and increase in ambient temperature are amongst the other factors that have become major environmental issues in recent years. Exposure to very low levels of elements such as lead, cadmium and mercury have been shown to have a cumulative effects on humans since there is no homeostatic mechanism that can operate to regulate the levels of these toxic substances (Carter and Fernando 1979). This study reports the levels of dissolved trace elements and heavy metals in the ground water system. The coastal area supports a rapidly growing population and there are concerns regarding the water quality of the ground water system. The main uses of water in the catchment area are domestic and agricultural (livestock watering) (Carter and Fernando 1979). Therefore, the presence of high concentration levels of heavy metals in the environment presents a potential danger to human health due to their extreme toxicity (Fatoki et al. 2012). The objective of this study was to assess the heavy metal and microbiological concentration in the groundwater samples of Thoothukudi Corporation, South Coast of Tamil Nadu, Gulf of Mannar and its relation to the highly developed industrial activities. The area is highly industrialized, and it is the main source of pollution. The waste products released from the anthropogenic activities like poultry farms, chemical, pharmaceuticals, and other industries constitute the main cause for the degradation of water quality in the area. Considering this factor and keeping an account of the importance of public health, this study was designed to understand the present status of trace elements and microbiological quality in groundwater of coastal city of Thoothukudi, Tamil Nadu, India. The results obtained will establish a baseline data for future reference.
Materials and methods
Groundwater well inventory and characteristics in the study area
Total depth (m)
Depth to water table (m)
Camp I quateres
State bank colony
Ayya samy street
Microbiological quality of water was determined using most probable number (MPN) methods (International Organization for Standardization, 2000). Groundwater samples were analysed for total coliform bacteria, faecal coliform bacteria, Escherichia coli and faecal streptococci. The MPN method was used to determine the presence of gas producing lactose fermenters and MPN of coliforms present in 100 mL of water. After 24 h of incubation at 37 °C in Lauryl Sulphate Tryptose Broth, tubes with turbidity and gas production were recorded as total coliform bacteria and a loopful of culture from the positive tubes was transferred into EC broth. Tubes with turbidity and gas production were recorded as faecal coliform bacteria after 24 h of incubation at 44.5 + 0.5 °C. From the positive tubes of EC broth, a loopful of culture was streaked on Eosine methylene blue agar (EMB), and colonies showing metallic sheen were recorded as presumptive E. coli. Further, typical colonies on EMB agar were purified and subjected to IMViC tests and confirmed as E. coli. Pour plate technique using Kenner Faecal agar was employed for the estimation of faecal streptococcal count, and typical colonies were counted after incubation at 37 °C for 48 h and expressed as colony forming unit (CFU) per ml or g of the sample. Salmonella was confirmed following standard procedures (AOAC 1998). Salmonella was detected by pre-enrichment in lactose broth, selective enrichment in tetrathionate broth and selenite cysteine broth, followed by selective plating on Xylose Lysine Deoxycholate agar and Bismuth sulphite agar. Typical colonies were purified them subjected to biochemical tests and finally confirmed serologically using poly ‘O’ and poly ‘H’ antisera (AOAC 1998).
Concept of IDW
The base map of Thoothukudi area was digitized from survey of India toposheet using ArcGIS 9.3 software. The precise locations of sampling points were determined in the field using GARMIN 12 Channel GPS, and the exact longitudes and latitudes of sampling points are imported in GIS platform (Selvam et al. 2014d, f). The spatial distribution for groundwater quality parameters like trace elements and bacterial elements was done with the help of spatial analyst modules in ArcGIS 9.3 software. Inverse distance weighted (IDW) interpolation technique was used for spatial modelling. IDW interpolation determines cell values using a linearly weighted combination of a set of sample points. The weight is a function of inverse distance. Further an input point is from the output cell location, the less importance it has in the calculation of the output value. The output value for a cell using IDW is limited to the range of the input values used to interpolate. Because the IDW is a weighted distance average, the average cannot be greater than the highest or lesser than the lowest input. Therefore, it cannot create ridges or valleys if these extremes have not already been sampled. Also, because of the averaging, the output surface will not pass through the sample points. The best results from IDW are obtained when sampling is sufficiently dense to represent the local variation that needs to be simulated. Thus, IDW technique is ideal for analysis in respect of water quality data from various sampling points densely spread out. If the sampling of input points is sparse or very uneven, the results may not adequately represent the desired surface.
Results and discussion
Salient features of major ion chemistry
Statistical measures such as minimum, maximum, average and standard deviation in pre-monsoon period
Water quality parameters
Pre-monsoon period (PRM)
Heavy metal distribution
For the protection of human health, guidelines for the presence of heavy metals in water have been set by different International Organisations such as United States Environmental Protection Agency, World Health Organization (WHO) and the European Union Commission (Marcovecchio et al. 2007). Thus, heavy metals have permissible limits in water as specified by these organizations. The summary of the heavy metal results of laboratory analyses conducted on the samples are in Table 1.
Statistical measures such as minimum, maximum, average and standard deviation in pre-monsoon period
Water quality parameters
Percentage of samples exceeding allowable limits in WHO (2004)
Chromium concentration in the groundwater varies from 0.001 to 0.080 mg/l with an average concentration of 0.013 mg/l. As per WHO 2004 standard only one sample exceeds the permissible limit, which may be due to industrial activity. The most common man-made sources of chromium in groundwater are burning of fossil fuels, mining effluent, effluent from metallurgical, chemical and other industrial operations (Leung and Jiao 2006). The risk to human health is through ingestion only—drinking, cooking and teeth brushing. Well water with chromium levels greater than 0.05 mg/l may safely be used for bathing, hand washing and dishwashing (Selvam et al. 2015).
The concentration of antimony in the groundwater varies from 0.000 to 0.007 mg/l with an average concentration of 0.001 mg/l. The maximum allowable limit of selenium ion concentration in groundwater is 0.005 mg/l as per WHO 2004 classification. Especially, people who work with antimony suffer the effects of exposure by breathing in antimony dusts. Human exposure to antimony may take place not only by breathing air, drinking water and by eating foods that contain it but also by skin contact with soil, water and other substances that contain it (Sang et al. 2008).
Cadmium concentration in the groundwater varies from 0.000 to 0.002 mg/l with an average concentration of 0.000 mg/l. The range of nickel concentration in groundwater varies from 0.000 to 0.011 mg/l, with an average concentration of 0.005 mg/l. The range of molybdenum concentration in groundwater varies from 0.000 to 0.008 mg/l, with an average concentration of 0.002 mg/l. The concentration of barium in the groundwater ranges from 0.000 to 0.057 mg/l with an average concentration of 0.012 mg/l. The concentration of rubidium in the groundwater varies from 0.000 to 0.850 mg/l, with an average concentration of 0.107 mg/l. In the study area, copper concentration varies from 0.002 to 0.236 mg/l with an average concentration of 0.031 mg/l. Zinc concentration in groundwater of the study area varies from 0.000 to 0.870 mg/l with an average concentration of 0.20 mg/l. Manganese concentration in the groundwater ranges from 0.000 to 0.424 mg/l with an average value of 0.040 mg/l. The concentrations of cadmium, nickel, molybdenum, barium, rubidium, copper and zinc in groundwater are within the maximum allowable limit as per WHO standard.
Cobalt concentration in the groundwater ranges from 0.000 to 0.027 mg/l with an average value of 0.002 mg/l, while Vanadium concentration in the groundwater varies from 0.002 to 0.052 mg/l with an average concentration of 0.010 mg/l. The range of silver concentration in groundwater varies from 0.000 to 0.002 mg/l, with an average concentration of 0.000 mg/l. The concentration of strontium in the groundwater varies from 0.000 to 2.000 mg/l, with an average concentration of 0.504 mg/l. BIS and WHO have not given any guideline value for Cobalt, Vanadium, Silver and Strontium concentration in the groundwater. The strontium concentration was higher in the study area indicating that the source could be anthropogenic through agricultural activities an input of strontium to some extent it depends on the content of fertilisers and carbonate additives and manure like cattle, poultry, etc. (Negrel et al. 2004). Strontium concentrations in soil may also be attributed to dumping waste and industrial wastes. Strontium in soil dissolves in water, so that it would be able to leach deeper into the ground and enter the groundwater.
Results of faecal indicator bacteria in the study area
Total coliform bacteria (MPN ml−1)
Faecal coliform bacteria (MPN ml−1)
Escherichia coli (MPN ml−1)
Faecal streptococci (CFU ml−1)
9.20 × 102
Est. < 10
Fishing old Harbour
2.00 × 101
5.00 × 102
1.00 × 101
7.40 × 102
Monitoring of water and soil in the vicinity of the toxic metal processing units needs to be carried out more rigorously for the specific metal.
Recycling/reprocessing of wastes containing toxic metals and biological contamination needs to be given greater emphasis not only from environmental and health considerations but also as a resource conservation measure.
Guidelines for proper management of tailings and slags containing toxic metals should be prepared taking into consideration techno-economic feasibility.
Tailings dumps and process wastes lying in locations close to the processing units need to be remediated on priority.
Health monitoring of workers engaged in the processing of toxic metals/compounds should be carried out regularly.
This study shows that the Thoothukudi Corporation of Tamil Nadu has been affected by trace elements and microbiological contamination in groundwater. The study reveals that Arsenic, Selenium, Lead, Bismuth, Aluminium, Iron and Vanadium are, in general, concentrated above the permissible limit (WHO 2004) in groundwater of the area of investigation. The increasing concentration of these elements in the groundwater of the study area is mainly originating from industrial effluents of copper industries, alkali chemical industry, fertiliser industry, thermal power plant, sea food industries, shipping activities and also from municipal waste water. Faecal pollution was found that fishing old harbour, mappillaiurani beach and thirespuram are highly affected from total coliform bacteria, faecal coliform bacteria and E. coli. This might be due to the mixing of sewage from Thoothukudi town through the Buckle channel and fishing activity.
In view of these findings, there is a need to monitor more closely the environment under review and put in place appropriate checks and balances to preserve the health of communities within the vicinity of the industrial areas, as the effects of heavy metals are bio-accumulative and pose great dangers to the health of humans, animals and plants. From the results of the present study, we can suggest that the Government should adopt some treatment technologies in the following study areas to minimize these heavy metals in groundwater and surface water for providing safe drinking water to the public.
The author S.Selvam is thankful to Department of Science and Technology, Government of India, New Delhi for awarding INSPIRE Fellowship to carry out this study (Ref. No. DST/INSPIRE FELLOWSHIP/2010/(308), Date: 3rd August 2010). Thanks are also due to Head, Geochemical Division, National Geophysical Research Institute, Hyderabad, India for providing facility to carry out the trace element analysis of the water samples in ICPMS lab at NGRI. This study was also supported by the Fisheries College and Research Institute, Tamil Nadu Veterinary and Animal Sciences University, Thoothukudi-628 008, India.
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