Underground water pollution in kerala

Dr Sharon A J MVSc Scholar

KVASU,CVAS mannuthy

Groundwater pollution

Occurs when pollutants are released to the ground and make their way down into groundwater. It can also occur naturally due to the presence of a minor and unwanted constituent, contaminant or impurity in the groundwater, in which case it is more likely referred to as contamination rather than pollution.

The pollutant creates a contaminant plume within an aquifer. Movement of water and dispersion within the aquifer spreads the

pollutant over a wider area. Its advancing boundary, often called a plume edge, can intersect with

groundwater wells or daylight into surface water such as seeps and spring, making the water supplies unsafe for humans and wildlife.

Pollution sources

Pollution can occur from on-site sanitation systems, landfills, effluent from wastewater treatment plants, leaking sewers, petrol stations from over application of fertilizers in agriculture. naturally occurring contaminants, such as arsenic or fluoride.

Transport of pollutants

Analysis of groundwater pollution may focus on soil characteristics and site geology, hydrogeology, hydrology, and the nature of the contaminants.

Different mechanisms have influence on the transport of pollutants, Diffusion Adsorption Precipitation Decay

Scenario

Kerala is one among the most thickly populated region in the world Population is increasing at a rate of 14% per decade. The needs of the huge population resulted in the over utilisation of the

water bodies The rivers of Kerala have been increasingly polluted from the industrial

and domestic waste and from the pesticides and fertilizer in agriculture. There are local level quality problems faced by all rivers especially due to

dumping of solid waste, bathing and discharge of effluents. Industries discharge hazardous pollutants like phosphates, sulphides,

ammonia, fluorides, heavy metals and insecticides into the downstream reaches of the river.

Examples

The periyar and chaliyar rivers are very good examples for the pollution due to industrial effluents.

it is estimated that nearly 260 million litres of trade effluents reach the Periyar estuary daily from the Kochi industrial belt.

The major water quality problem associated with rivers of Kerala is bacteriological pollution.

The assessment of river such as Chalakudy, Periyar, Muvattupuzha, Meenachil, Pamba and Achenkovil indicates that the major quality problem is due to bacteriological pollution and falls under B or C category of CPCB classification.(Central pollution control board)

Ground water Groundwater, water quality characteristics of wells in Kerala are found to be affected by

chemical and biological contaminants. The ground water quality problems in the coastal areas are mainly because of the

presence of excess chloride. The chloride concentration >250mb/l was detected in the well water samples of

Azhicode, Kakkathuruthy, Edathinjil, Kadalundi, Chellanum, nallalam, Mankombu and Harippad.

Ground water contamination due to industrial pollution has been reported from places of Kochi (eastern part of Aluva), Palakkad and some parts of Kollam, Kozhikode and Kannur.

Alappuzha district, fluoride concentration in the pumping wells was observed to be high. In midland region, with regard to ionic concentration, the concentration of fluoride and

chloride ion were found to be high. The fluoride content was observed to be beyond the permissible limit of 1 mg/l. Deep wells in Chittur taluk and Knajikod areas of Palakkad district are found to contain

flouride concentration greater than 1the permissible limit

Open well Open well of Kerala are under threat of bacteriological contamination. In Kerala about 60% of the population relies on ground water for drinking. Studies have shown that faecal contamination is present in 90% of drinking water

wells. Reason The open character of the wells, conventional maintenance habits use of buckets and rope to draw water kitchen wastes and pit latrines with average family load factor (5 members) at a

distance of less than 5 meters from wells.

Water standards

The impact of concentration of various ions in water or human health and plants, various standards have been laid down by different agencies.

These standards are useful for deciding the suitability of water for drinking and irrigation purposes.

The standards approved by Bureau of India Standards (BIS 10500-91) for drinking water is followed.

They specify the following limits for different parameters. The Physical, Chemical and Bacteriological quality of water should not exceed the limits.

Limits

http://www.groundwater.kerala.gov.in/english/anelytical.htm

Ground water pollution

Ground water contamination denotes basically chemical and bacteriological pollution to a degree that inhibits the use of water or that creates an actual hazard to public health through poisoning or the spread of diseases.

Reasons industrial production Agriculture sewage discharge urbanization, commercial and residential activates contaminate groundwater sources.

The domestic sewage composed of faecal waste, kitchen, laundry waste are the major sources of pollution for the household wells.

Physico-chemical contamination Fluoride problems

The concentration of fluoride in drinking water is critical considering health problems related to teeth and bones.

High fluoride concentration causes dental fluorosis and skeletal fluorosis whereas the absence or low concentration of fluoride in drinking water results in dental caries in children particularly when the fluoride concentration is less than 0.5 mg/L.

In India fluoridation is not needed since we are getting sufficient fluorides from other food items. The recommended desirable limit of fluoride in 1 mg/L.

Spatial variation of fluoride in well water

http://wgbis.ces.iisc.ernet.in/biodiversity/pubs/ces_tr/TR133/section9.htm

Flourosis

Regions in Kerala affected with Fluorine contamination From June 1999 onwards constant monitoring were conducted for fluoride

concentration in the KWA and other tube wells developed in Alappuzha district. Most of the KWA wells are located in the Warkali aquifer. As compared to the 1995-96 values there is an increasing trend in the fluoride

concentration as compared to other tube wells. This is due to over pumping.

A slight decrease in fluoride concentration is observed after the monsoon period. This is due to the dilution effect of the monsoon.

The over exploited wells in the municipal area has more flourine. It is also noted that in the fluoride prone areas as the depth increases the fluoride concentration also increases.

Higher values of fluoride are also observed in some pockets of Palakkad district mainly in Chittoor, Kollengode, Palakkad and Malampuzha areas.

Iron contamination in kerala

The acceptable limit of iron is 0.3 mg/L and the desirable limit is 1 mg/L. Beyond these limits, taste and appearance are affected. It has adverse effects on domestic uses like staining of plumbing and fixtures, oily

appearance on top of water body, deposits on boiling, coloration to the food prepared, promoting iron bacteria etc.

Iron values are seen above acceptable limit in many of the wells overall the state.

On Public interest in Kallelibhagam, Karunagappaly in Kollam District the department of ground water made an investigation on the problems related to water quality.

The main complaint of the public was the brown colouration of the well water. 13 water samples were collected and analysed. The study revealed that almost all the

wells were contaminated with iron. Value has gone even to 14.6 mg/L.

Acidity problems

Acidity is mainly due to lower pH values. The acceptable limit of pH value is between 6.5 to 8.5. When the value is below 6.5, water is said to be acidic. Beyond this range, the

water will affect the mucous membrane and water supply systems.

As the local people near Venjarammood, Thiruvananthapuram reported burning of eyes and itching and requested investigation, samples were collected from open wells in and around the area by the Ground water department and on analysis it has been observed that all the samples were acidic.

Water hardness

Desirable limit of hardness is 300 mg/L.

Higher values are problematic in the sense that it produces encrustation in water supply structures; in the domestic use it affects lathering of detergents.

Higher values are noted mainly in Alappuzha and Palakkad areas and in certain areas of Ernakulam, and Thrissur.

Chlorides

Some common chlorides include sodium chloride (NaCl) and magnesium chloride (MgCl2)

Small amounts of chlorides are required for normal cell functions in plant and animal life.

Effects on environment and human health: Chlorides are not usually harmful to people; however, the sodium part of

table salt has been linked to heart and kidney disease. Sodium chloride may impart a salty taste at 250 mg/L; however, calcium or magnesium chlorides are not usually detected by taste until levels of 1000 mg/L are reached.

Chlorine sources

Chlorides may get into surface water from several sources including

1) Rocks containing chlorides 2) Agricultural runoff 3) Wastewater from industries 4) Effluent wastewater from wastewater treatment plants.

Effects of chlorine

Chlorides can corrode metals Affect the taste of food products. Therefore, water that is used in industry or processed for any use has a

recommended maximum chloride level. Chlorides can contaminate fresh water streams and lakes. Fish and

aquatic communities cannot survive in high levels of chlorides.

Spatial distribution of chlorides in well water

http://wgbis.ces.iisc.ernet.in/biodiversity/pubs/ces_tr/TR133/section9.htm

Bacteriological Contamination

Varieties of water borne diseases are attributed to untreated or inadequately treated ground water containing pathogenic forms of bacteria.

Biological contamination of ground water may occur when human or animal waste enters an aquifer.

Standard test to determine the safety of ground water for drinking purposes involves identifying whether or not bacteria belonging to coliform group are present.

The recent faecal pollution of water sources are indicated by the presence of coliform bacteria viz., Escherichia coli.

The result of coliform test is reported in terms of Most Probable Number (MPN/100 ml) of coliform group of organism present in a given volume of water. The count must not be detectable in any 100 ml sample.

From the public water sample that are being analysed regularly by ground water department. About 70% of the wells of Thiruvananthapuram and Kollam are contaminated with coliform.

The most sacred river in Kerala, Pamba river flowing through Sabarimala is polluted during the festive season of November-December period every year.

Lakhs of devotees from all over the country specifically from Southern States of India throng the very auspicious temple of Lord Ayyappa, situated in Sabarimala during this 45-day period.

Samples were collected from the open wells bordering certain areas of the Pamba River by ground water department, immediately after the festive season of November-December 2002.

On analysis presence of coliform bacteria has been established in al the samples. This very clearly establishes the pollution of ground water aquifers by surface water pollution and in such areas one cannot go unscathed even if open well water is used.

In association with GREENS, an NGO a study was conducted on deterioration of quality of Karamana River,

The main source of municipal water supply for the city of Thiruvananthapuram. Human activities are polluting the river in many ways 1.sand mining 2. brick making 3. waste disposal 4. sewage disposal.

Effects on Environment and Human Health

Total coliforms should be absent immediately after disinfection, and the presence of these organisms indicates inadequate treatment. The presence of total coliforms in distribution systems and stored water supplies reveal regrowth and possible biofilm formation or contamination through ingress of foreign material, including soil or plants.

Large quantities of Faecal coliform bacteria in water may indicate a higher risk of pathogens being present in the water. Some waterborne pathogenic diseases include ear infections, dysentery, typhoid fever, viral and bacterial gastroenteritis, and hepatitis A. The presence of faecal coliform tends to affect humans more than it does aquatic creatures.

Standard

For water entering a distribution system

Coliform count in any sample of 100 ml should be zero (0).

For water in a distribution system –

E coli count in 100 ml of any sample must be zero (0). Coliform organisms should not be more than 10 per 100 ml in any sample.

Coliform organisms should not be present in 100 ml of any two consecutive samples or more than 5% of the samples collected for the year.

Faecal coliform in surface water

Faecal Coliform in well water

Sea water ingress Kerala has about 600 kms long coast line. Coastal sedimentary formations are seen all along the Kerala coast but

the prominent area lies between Ponnani in Malapuram district and Veli in Trivandrum district.

Geomorphologically, the area is dissected by numerous rivers, backwater channels and lakes. In two areas namely

Kuttanadu and Kole altitude of land surface lies below mean sea level. The shallow aquifers tapping the coastal alluvium are generally fresh

with isolated pockets of saline water developed during summers close to the backwater channels, lakes and the tidal rivers.

Amongst the Tertiary beds the aquifers in Vaikom beds hold fresh water to the south of Karuvatta in Alleppey district.

The salinity/brackishness of groundwater is due to leaching of salts from the aquifer material (insitu) and not due to sea water intrusion.

Sea water ingress to the coastal aquifers due to over extraction is not reported from the Kerala Coast.

However salinity is noticed in shallow wells close to the backwaters, lagoons, lakes and the tidal rivers.

The rivers of Kerala often encounter salinity intrusion into their lower stretches during summer months.

When the fresh water flow reduces, two major problems are encountered in these water bodies

(i) salinity propagates more into the interior of the river (ii) flushing of the system becomes less effective. Both these have an

impact on groundwater based water supply wells and other wells situated close to the rivers.

Problems of salinity intrusion are also encountered in Bharathapuzha, Periyar, Meenachil and Kuttiyadi rivers.

The extensive sand mining in riverbeds may further damage the system.

Problems associated with pesticides and insecticides Numerous studies over the past four decades have established that

pesticides, which are typically applied at the land surface, can move downward through the unsaturated zone to reach the water table at detectable concentrations.

The downward movement of pesticide degradation products, formed in situ, can also contribute to the contamination of ground water.

Once in ground water, pesticides and their degradation products can persist for years.

Depending upon the chemical structure of the compounds and the environmental conditions.

Groundwater Protection

Contamination of Groundwater is more complex than surface water pollution mainly because of difficulty in its timely detection and slow movement.

In addition the complex geo-chemical reactions taking place in the subsurface between myriad contaminants and earth materials are not always well-understood.

Ideally speaking contamination should be prevented from occurring. After a contaminant or several contaminants are found in groundwater,

a decision must be made on whether to rehabilitate the aquifer or find alternative groundwater resources.

Conclusion

Traditionally dug wells met the drinking water needs and rivers, streams and ponds met irrigation and other needs of rural people in the state.

Urban populace mainly depends on piped water supply (surface water) for their needs.

Now after introduction of piped water supply to the rural area, the old Panchayath wells and other water bodies are being neglected.

Groundwater below the land surface being invisible, the common man could not judges its availability in terms of the depth to groundwater table and quality.

Due to absence of any pricing mechanism and strict regulation, indiscriminate groundwater exploitation, its wasteful utilization, and land disposal of wastes continued.

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