WATER QUALITY ISSUES
Contamination can enter the water bodies through one or more of the following ways:
Water quality issues needing to be addressed with respect to different water bodies are presented below.
Change in Physical Characteristics
Temperature, turbidity and total suspended solids (TSS) in rivers can be greatly affected by human activities such as agriculture, deforestation and the use of water for cooling. For example, the upward trend in soil erosion and the related increase in TSS in rivers can be seen in most of the mountainous regions in India.
Contamination by Faecal and Organic Matter
In India faecal contamination is still the primary water quality issue in rivers, especially where human and animal wastes are not adequately collected and treated. Although this applies to both rural and urban areas, the situation is probably more critical in fast-growing cities.
The release of untreated domestic or industrial wastes high in organic matter into rivers results in a marked decline in oxygen concentration (sometimes resulting in anaerobic conditions) and a rise in ammonia and nitrogen concentrations, downstream of the effluent input. The most obvious effect of the release of organic matter along the length of the river is the depletion of oxygen downstream of the discharge as shown by the so-called 'oxygen-sag curve' which plots dissolved oxygen concentration against distance. Industrial activities which discharge large organic loads include, pulp and paper production and food processing: Faecal matter affects the use of water for drinking water source or bathing water, as well as ecological health of river.
Toxic Pollutants: Organics and Heavy Metals
Organic pollutants (Mostly chemicals manufactured artificially by man) are also becoming an important water quality issue. They enter rivers as:
Uncontrolled discharge of industrial wastewater often causes pollution due to toxic metals. Other sources of metal pollution are leachates from urban solid waste landfills and mining waste dumps.
Rivers such as the Yamuna, which pass through large towns and cities, are often badly affected with organic pollutants. Another example is that of Damodar River which is polluted with heavy metals arising mostly from electroplating, tanning and metal based industries.
During the 1950s and 1960s, eutrophication (nutrient enrichment leading to increased plant arid algae growth) was observed mostly in lakes and reservoirs. Since the 1970s the increasing levels of phosphates and nitrates entering rivers, particularly in developed countries were largely responsible for eutrophication occurring in running waters. In India isolated reports have appeared for some river reaches especially in plains around agriculture tracts of land.
In small rivers eutrophication is said to promote macrophyte (large plants) development, whereas in large rivers phytoplankton (algae) are usually mere dominant than macrophyte. In such situations the chlorophyll concentration of the water may reach extremely high values due to the fact that this pigment is present in all plants
Eutrophication can result in marked variations in dissolved oxygen arid pH throughout the day. The changes in water quality caused by eutrophication can be a major cause of stress to fish due to the release, at high pH, of highly toxic gaseous ammonia and depletion of oxygen after sunshine hours.
Increased mineral salts in rivers may arise from several sources:
Industrial and mining waste pollution results in increase in specifications. Evaporation however, increases the concentration of all ions.
Changes in River Hydrology
Many human activities, directly or indirectly, lead to modifications of river channels, which can, in turn, induce changes to the aquatic environment. Major modifications to river Systems include the following:
to depth and width for navigation creation of flood control ponds
· creation of reservoirs for drinking water supply
· damming for hydroelectric power generation
· diversion for irrigation purposes
All of the above affect the hydrology and related uses of the river system and so have a great potential to affect water quality. It must be remembered, however, that not all such water quality changes are necessarily deleterious.
Unsewered Domestic Waste
Under certain hydrogeological conditions, unsewered domestic waste can cause severe groundwater contamination by pathogenic bacteria, nitrate and other pollutants. Unsewered waste normally means septic tanks or pit latrines of the ventilated, dry or pour-flush types. There are important differences between the two in relation to the risk of groundwater contamination. Septic tank soakaways discharge at a higher levels in the soil profile than pit latrines and such conditions are preferable as far as the elimination of bacteria is concerned. Pit latrines are often deep excavations (to allow a long useful life) and the soil may be entirely removed thus offering less opportunity for bacterial death. Further the loading from septic tank soakaways is likely to be less than for some of the pit latrine types. Septic tanks are lined and their solid effluent of high nitrogen content is periodically removed, whereas most pit latrines are unlined and the solid material remains in the ground. The impact of unsewered domestic waste is felt particularly in relation to the contamination of groundwater drinking water supplies.
In India, the percentage of sewered population is nearly negligible in most of the rural areas and is quite meager (0 to 50%) in most medium and small towns. As a result, the contamination of groundwater by pollution from unsewered areas is one of the most important environmental problems facing the country.
Disposal of Liquid Urban and Industrial Waste
Methods of wastewater disposal include infiltration ponds, spreading or spraying onto the ground surface and discharge to stream or dry stream beds, which if not carefully regulated may provide a rapid pollution pathway to underlying, shallow aquifers. In some areas, deep soakaways or abandoned wells are used for the disposal of liquid domestic, industrial or farming wastes into aquifers. Lack of monitoring, supervision or management adds to the problem.
Even if the intention is to dispose of the waste at depth, improper sealing or corrosion of well linings often produces leaks and subsequent pollution of the shallow groundwater which is used for water supplies. In urban areas covered by sewerage systems, an economical. and common, method of partial treatment of sewage is wastewater stabilisation by retention in shallow oxidation lagoons before subsequent discharge into rivers or onto land for irrigation systems. These lagoons are often unlined and, if constructed over coarse-textured soils, may have high rates of seepage loss. Further, the use of such effluent in irrigation may also lead to similar problems. Most of the unplanned industrial complexes and scattered industrial units in urban areas and the agricultural-related industries in remote villages are good examples of this type of pollution.
Disposal of Solid Domestic and Industrial Waste
The most common method of disposal of solid municipal waste in India is by deposition in landfills. In order to minimise the impact of such landfills on groundwater quality and the environment in general it is necessary to properly design and build these facilities to prevent pollution and put in place strict management controls to ensure they are operated correctly. Unfortunately this is rarely done as few towns and industries in the country make the necessary effort to ensure that their solid waste is treated or disposed of in a proper manner.
The principal threat to groundwater comes from inadequately controlled landfills where leachate generated from the fill material is allowed to escape to the surrounding and underlying ground. The chemical composition of such leachate depends on the nature and age of the landfill and the leaching rate. Most leachates emanating from municipal solid wastes are not only high in organic content but also contain some toxic material. Leachates from solid wastes of industrial origin, however, often contain a much higher proportion of toxic constituents, such as metals and organic pollutants.
Cultivation with Agrochemicals
Agricultural land use and cultivation practices have been shown to exert major influences on groundwater quality. Under certain circumstances, serious groundwater pollution can be caused by agricultural activities the influence of that may be very important because of the large areas of aquifer affected. Of particular concern, in India, is the leaching of fertiliser chemicals (e.g., nitrate) and pesticides from regular intensive cultivation of crops. The impact of cultivation practices on groundwater quality is greatest, as are most anthropogenic effects, where relatively shallow, unconfined aquifers are used for potable supply.
In India, a high proportion of the rural population in agricultural areas obtain their domestic water supplies from shallow, private bore holes, which suffer the impact of nitrate pollution to a much greater extent than the deeper, public supply aquifers utilised for urban water supply. These deeper aquifers can also be affected by nitrate contamination although this pollution often takes much more time to percolate to these depths.
Much less attention has been given in this country to the leaching of pesticides from agricultural land to the underlying groundwater in spite of the dramatic increase in the use of pesticide formulations over the last years. There are currently few laboratories with the capability of analysing pesticides.
Salinity from Irrigation
Increasing salinity resulting from the effects of irrigated agriculture is one or the oldest and most widespread forms of groundwater pollution. It is caused by the dissolved salts in irrigation water being deposited following evaporation of the water. The addition of further excess irrigation water merely leaches salts from the soil and transfers the problem to the underlying groundwater.
A range of groundwater pollution problems can be associated with mining activities. The nature of the pollution depends on the materials being excavated and extracted. Both surface and underground mines usually extend below the water table and often dewatering is required to allow mining to proceed. The water pumped either directly from the mine or from specially constructed bore holes, may be highly mineralised and its usual characteristics include low pH (down to pH 3) and high levels of iron, aluminium and sulphate. Disposal of this mine drainage effluent to surface water or groundwater can cause serious impacts on water quality for all uses. Pollution of groundwater can also result from the leaching of mine tailings and from settling ponds and can, therefore, be associated with both present and past mining activity.
Groundwater in certain geological formations may not be of desired quality for specific uses. Naturally occurring fluorides, arsenic and salinity are known to adversely affect the quality of water for drinking water supplies.
Lakes and Reservoirs Pollution Pathways
The following pathways, in addition to the ones mentioned above, assume special significance in the case of lakes and reservoir pollution;
In addition to the above, lakes serve as traps for pollutants carried by rivers and groundwater draining the watershed. The pollutant concentration in the lake usually builds up due to evaporation of water from the lake's surface unless there is a natural flushing with good quality water.
Simply speaking, eutrophication is the biological response to excess nutrient input to a lake. The production of biomass and its death and decay results in a number of effects, which individually and collectively result in impaired water use. The most important of these effects are decreased dissolved oxygen levels, release of odorous compounds (e.g. H2S) and siltation.
Many important lakes in India (e.g., Hussein Sagar (Hyderabad), Nainital (Uttar Pradesh) and Dal (Jammu and Kashmir) have reportedly progressed to advanced eutrophication levels.
One of the major issues related to lakes in particular, and to freshwaters in general, is the progressive acidification associated with deposition of rain and particulates (wet and dry deposition) enriched in mineral acids. The problem is characteristic of lakes in specific regions of the world, which satisfy two major critical conditions: the lakes must have soft water (i.e. low hardness, conductivity and dissolved salts) and be subjected to ‘acid rain’.
To date, lake acidification has not been reported as a problem in India.
Bioaccumulation and Biomagnification
The processes of bioaccumulation and biomagnification are extremely important in the distribution of toxic substances (discharged in waste effluents) in fresh water ecosystems. The concentration of pollutants within the organism due to bioaccumulation and biomagnification depends on the duration of exposure of the organism to the contaminated environment and its trophic level in the food chain. Several fold increases in trace contaminant concentrations have been commonly observed in lakes and estuarine environments.
GROUND WATER POLLUTION AND QUALITY HAZARDS SCENARIO IN INDIA
The rapid pace of urbanisation, industrialisation as well as agricultural activities have made environmental pollution a growing concern globally. Off all the receptor systems exposed to the contaminants, ground water has received little attention in the past because of the common belief that ground water was pristine.
Ground Water Pollution is usually traced back to four main origins industrial, domestic, agricultural and over exploitation. The last category mainly accounts for seawater intrusion. studies carried out in India reveal that one of the most important cause of ground water pollution is unplanned urban development without adequate attention to sewage and waste disposal. Industrialisation without provision of proper treatment and disposal wastes and affluent is another source of ground water pollution. Excessive application of fertilizers for agricultural development coupled with over-irrigation intrusion due to excessive pumping of fresh water in coastal aquifers are also responsible for ground water pollution.
Ground Water Pollution & Hazards Scenario in India
With the declared objectives of providing at least the basic amenities there has been a tremendous development in India, in the agriculture and industrial sector, with concomitant pressure on the fresh water resources. The waste generated by anthropogenic activities has not only polluted the environment as a whole but had a particular detrimental effect on the quality of aquatio-envison too. Leachates from compost pits, animal refuse of garbage dumping grounds nutrient enriched return irrigation flows seepage from septic tanks, seepage of sewage etc. has adversely affected the ground water quality in several parts of India. The rate of generation of wastewater in India during 1981 was estimated to be 74,529 million litresday i.e. about 27km3 annually, which poses a perennial danger to the potable ground water resource. The gravity of situation can be judged from the act that inspite of sewage treatment plant, Delhi discharged 100 million gallon of untreated sewage into the Yamuna. The problem is likely to compound further with increasing rate of wastewater generation which is estimated about 40km3 (110,000 million litre/day) annually by the year 2000 when the population is estimated to be around one million. Solid waste disposal is also not lagging behind in adding to ground water pollution problem. With increase of human and livestock population the quantum of waste produced has increased tremendously. The estimated annual waste production from these sources is around 2000 million tons (Vimal & Tala Shilkar, 1983). Studies on chemical composition of ground water in phrestic zone have revealed that in many cases a nomalously high concentration of Nitrate Potassium and even phosphate (total phosphate) are present in contrast to their virtual absence or low concentration (No.3 and K less than l0 mg/l) in semi-confined and aquifers. Unsystematic use of synthetic fertilizers couple with improper water management practices have resulted in deterioration of ground water quality in many parts of the country.
In case of industrial units, effluent in most of the cases are discharged into pits, open ground, or open unlined drains near the factories, thus allowing it to move to low lying depressions resulting ground water pollution. The industries which are burgeoning at terrifying fast rate, daily produce about 55000 million M3 of wastewater per day, out of which 68.5 million M3 is discharged into river streams. Thus the magnitude of damage caused to our water resources can be estimated from the fact that about 70% of rivers and streams in India contain polluted water.
The incidence of ground water pollution is highest in urban where large volume of waste are concentrated and discharged into relatively small areas. The ground water contamination, however, is detected only some time after the subsurface contamination begins.
Thirteen states in India have been identified as endemic to fluorosis due to abundance in natural occurring fluoride bearing minerals. These are Nalgonda, Rangaraddy district in A.P., Banskatha, Kutch, Amroli in Gujarat, Hissar, Kaithal, Gurgaon in Haryana, Augul Bolengir, Phulbani in Orissa, Bhatinda, Sangrur in Punjab, Ajmer, Bikaner, Pali, Nagur, Sirohi in Rajasthan, Chengalpatti, Madurai in Tamilnadu, Unnao in U.P., Karnataka, Madhya Pradesh, Maharastra, Bihar, Delhi. There are nearly half million people in India suffering from ailment due to excess of fluoride in drinking water. In some villages of Rajasthan and Amroeiditits in Gujarat level of the fluoride goes up to 11.0 mg/lit.
Though iron content in drinking water may not affect the human system as a simple dietary overload, but in the long run prolonged accumulation of Iron in the body may result in homochromatosis, where it issues are damaged. In some districts of Assam (Barpota, Darrang, Kamrup, Sonipni) and Orissa (Balasore, Cuttack, Puri) ground water have high iron content ranging from 1 to 10mg/l.
A total of 10,6019 sq. km area (about 31 %) of Rajasthan comes under saline ground water in the state of this 88675 Sq. km area falls in western Rajasthan of Ganganagar, Barmer, Bikaner, Churu and Jaisalmer districts. The electrical conductivity of ground water in western Rajasthan is over 8ds/cm and in eastern Rajasthan over 6ds/cm. Vast low lying alluvial tract from North-Western part of Banaskantha district through the western part of Mashing and Ahmedabad districts western and north-eastern parts of Surendranagar district, Southern part of Ahmedabad and South-Western part of Kheda district is underlain by saline ground water (EC 3.46 ds/cm). Ground Water in Sangrur, Bhatinda, Ferozpur and Faridkot districts have on high as 11.30 ds/cm salinity. Groundwater is saline in almost all the canal Bhakra canal and the lift canal system of South-Western part of Haryana. About 3766sq. km. area in Haryana is underlain by saline ground water (EC 6 ds/cm.).
Arsenic in ground water have been reported in a range (0.05-3.2) mglp in shallow aquifers from 61 block in 8 districts of West Bengal namely Malda, Mushirbad, Nadia, North and South 24 Pargana, Bardharnan, Howrah and Hugli.
GROUND WATER POLLUTION IN INDIA
Place of occurrences
|Salinity (Inland)||Maharashtra||Amravati, Akola|
|Rajasthan||Barmer, Jaisalmer, Bharatpur, Jaipur, Nagaur, Jalore & Sirohi|
|Salinity (Coastal)||Andhra Pradesh||Vishakapatnam|
|Orissa||Puri, Cuttak, Balasore|
|West Bengal||Haldai & 24 Pargana|
|Gujarat||Junagarh, Kachch, Varahi, Banskanta & Surat|
|Flouride||Kerala||Palaghat Krishna, Ananipur, Nellor, Chittoor.|
|Andhra Pradesh||Cuddapah, Guntur and Nalgonda|
|Gujarat||Banskanta, Kachch & Amreli|
|Haryana||Hissar, Kaithal & Gurgaon|
|Orissa||Bolangir, Bijapur, Bhubaneshwar and Kalahandi|
|Punjab||Amritsar, Bhatinda, Faridkot, Ludhiana & Sangrur|
|Rajasthan||Nagaur, Pali, Sirohi, Ajmer & Bikaner|
|Tamil Nadu||Chengalput, Madurai|
|U.P.||Unnao, Agra, Aligarh, Mathura, Ghaziabad, Meerut & Rai Baraili|
|Sulphide||Orissa||Balasore, Cuttak & Puri|
|Assam||Darrang, Jorhat, Kamrup|
|Bihar||E. Champaran, Muzaffarpur, Gaya, Manger, Deoghar & Madubani|
|Rajasthan||Bikaner, Alwar, Bharatpur|
|Tripura||Dharmnagar, Kailasanar, Ambasa, Amarpur & Agartala|
|West Bengal||Madnipur, Howrah, Hoogly and Bankura|
|U.P||Muradabad, Basti, Rampur & Unnao|
|Arsenic||West Bengal||Malda, Murshidabad, Nadia, 24 Pargana|
|Nitrate||Bihar||Patna, East Champaran, Palamu, Gaya, Nalanda, Nawada and Banka|
|Andhra Pradesh||Vishakapatnam, East Godvari, Krishna, Prakasam, Nellor, Chittoor, Anantpur, Cuddapah, Kurnool, Khamam and Nalgonda|
|Delhi||Naraina, Shehadr (Blocks)|
|Haryana||Ambala, Sonepat, Jind, Gurgaon, Faridabad & Hissar|
|Himachal Pradesh||Kulu, Solan, Una|
|Karnataka||Bidar, Gulbarge and Bijapur|
|Madhya Pradesh||Sehore, Bhopal & (West & Central Part of state)|
|Maharashtra||Jalna, Beed Nanded, Latur, Osmanabad, Solapur Satara, Sangli and Kolhapur|
|Punjab||Patiala, Faridkot, Firozpur, Sangrur & Bhatinda|
|Rajasthan||Jaipur, Churu, Ganganagar, Bikaner, Jalore, Barmer, Bundi and Sawaimadhopur|
|Tamil Nadu||Coimbatore, Penyar and Salem|
|West Bengal||Uttar Dinajpur, Malda, Birbhum, Murshidabad, Nadia, Bankura and Purulia.|
|Madhya Pradesh||Bhind, Shagapur and Sehore|
|Maharashtra||Solapur, Satara, Amravati, Akola & Buldana|
|Rajasthan||Barmer, Jaisalmer, Jodhpur & Jalore|
|West Bengal||Contai, Digha, Haldia|
|Zinc||Andhra Pradesh||Hyderabad, Osmania University campus|