Water resources are polluted by the wastes generated by the humans. Water in ponds, lakes, tanks, rivers, seas and oceans and in all other forms gets polluted by the human activities. On the one hand, there is a scarcity of water while, on the other, there is pollution of it.
Polluted water affects land and degrades it. Now let us look at how and why water pollution and land degradation occur.
1. Water draining from agricultural lands, carrying chemical pollutants;
2. Wastewater disposal in urban areas;
3. Industrial wastewater disposal;
4. Wastes disposed of and temperatures of wastes from industrial units such as atomic and other energy production units; and
5. Pollutants of oceans.
Wastes from human activities are the prime causes of water pollution. The indiscriminate dumping of wastes and the natural drainage of the water cause pollution to a greater extent.
Modern agriculture uses chemical fertilisers, insecticides and pesticides. Fertilisers broadcast in the cropped fields, insecticides and weedicides dusted on to the plants dissolve in the water - from rains and irrigation water - and are drained into canals and rivers. They finally reach the sea. It has been estimated that 83 per cent of the sea and ocean pollutants have human activity origins.
With urbanisation, scarcities in basic amenities have become the order of the day. There appears to be no plan for proper disposing of wastewaters from urban activities. Due to this shortcoming, wastewaters find their way to water bodies. In Chennai city, for example, the rivers such as the Cooum and Adyar carry domestic wastewater. Industrial also reach these and create a foul smell in the air. The rivers which were once the quality freshwater bodies have now become urban sewers. On the contrary, rivers such as the Thames of London and the Seine of Paris which were once much polluted and have now been cleaned up. The Ganges was also a heavily polluted river not long ago and has now been cleaned under the Clean Ganga Project. Yet, there are several water bodies in the cities and towns of the country which carry wastewaters. The hazardous chemicals which are carried in solution and suspension finally end up in the seas, causing water pollution there too.
Hazardous wastewaters from industries are also drained into the rivers and reach the oceans. As a consequence, the recycled water from the hydrological cycle is also a pollutant and contains contaminant traces. Food wastes, metal wastes and chemical wastes are not easily degradable. Hence, their traces are amplified over the years. Equally disturbing is the fact that radioactive wastes and high temperatures from it are transferred to the water bodies.
The countries which produce atomic energy claim that the production is for peaceful purposes but they dump the radioactive ashes along the coast, marsh lands and estuaries. This causes the temperature of the sea waters to rise. Consequently, its quality declines.
An estimate has it that nearly 200,000 tonnes of oil is lost as leaks from the industries into the water bodies. Oil spills in the oceans greatly affect the sea organisms, fish and sea animals. Human beings are affected when they consume sea food, including fish.
Another industrial by-product that pollutes water bodies greatly is the tannery effluent. It is often indiscriminately disposed of. In the tanneries, every 100 kg of skins and hides processed requires 3,000 litres of water. This water is used for soaking and is used in almost all processes of tanning. Almost the entire quantity of water used in tanning is disposed of as wastewaters. In places such as Vaniyambadi, Ambur and Ranipettai in North Arcot-Ambedkar, there are hundreds of tanning industries. Wastewaters are not treated before disposal. They are disposed of in the open and into the river Palar. The Palar irrigates lands in its command and thus pollutes the land as well. Even the few wastewater treatment plants in operation in the district are not functioning properly for reasons of power shortage and excessive flow of water.
Water pollution often leads to land degradation. Water infiltrating from the wastewater sources reaches the underground aquifers and contaminates the underground water. Land is degraded wherever surface waters and drainage and sewage channels carry wastewaters and wherever the sewers are either clogged or broken. Land resources of the urban areas are degraded due to indiscriminate solid wastes and wastewaters dumping in the open. In cities such as Chennai, Salem and Tiruchirappalli in Tamil Nadu, visual blight is appreciable. In the rural areas, however, such blight is hidden and thus are not immediately apparent, except where it is widespread. There are of course other types of land degradation. In the Kambam valley of Madurai and/or Theni districts, there is a stretch of land along the Western Ghats fully covered with sand dunes and sand encroached areas, known popularly as the 'theri sands'. This stretch is 120 sq. km in extent and therefore land degradation is over a vast area.
Although the irrigation water from the wells, rivers and canals is contaminated by solid wastes and wastewaters, chemicals such as fertilisers, pesticides and insecticides, there is only limited awareness of the degradation it causes in the rural areas. Worse, the farmers and the people are not even aware of it. Researches have shown the levels of pollution in such areas through careful measurements. For example, it has been found that the lands irrigated with polluted waters have declining yields. It has also been found that its impact would much depend on the levels of traces.
As a consequence of the events described above, negative impacts have now surfaced. These impacts have pushed us to the options of land and water conservation and management, and importantly earth's resources and its environment. There is a need therefore to work towards a sustainable future. This future has to be achieved through appropriate environmental and resources management. In regard to land and water, there has to be an integrated management, with an ethical framework. Towards this end, the following chapter speaks of water ethics and management.