POLLUTION OF WATER RESOURCES

Man cannot survive without water. The low population densities in the desert natural region is because of the water deficiency which renders vast areas of land uninhabitable. The sources of water include oceans, rivers, lakes, rainfall and groundwater. Unfortunately, man lowers the quality of these water sources through his numerous activities which lead to the pollution of the water bodies. Such pollutants include crude oil, sewage, industrial wastes, chemical fertilizers, and so on.

 

(a) Oil Pollution

In spite of the advantages of water bodies discussed above in this chapter, accidental oil spillage may cause immediate and local ecological disturbances. Oil spillage may occur when an oil tanker accidentally hits a rock in the high seas and gets damaged , or when there is a blowout from an oil well, or when something like a vehicle/pay-loader accidentally rips a hole in a crude oil pipeline. Routine spills may be due to leaking pipes, or from discharges into rivers or streams by tankers loading in terminals.

The first major world tanker accident occurred in the South West coast of England in 1967 when the Torrey Canyon, an oil tanker, ran on to the Seven Stone Rocks. The vessel was completely wrecked and it completely lost 100,000 tons of crude oil to the sea.

The Texaco Funiwa No. 5 oil well blowout of 17th January, 1980 in the Nigeria Delta is a fine example of oil pollution. The well was reported to have blown out during completion operation by the semi-submersible drilling rig. As the flow of oil from the well extended to the Sangana River, it affected the neighbouring villages of Kaluma I, Kaluma II, Sangana Fish Town and Otuo. There was some damage to the beaches; mangrove seedlings in the affected area were defoliated; and dead crabs and sea snails were noticed.

The Abudu Pipeline Oil Spillage of November, 1982 took place when a pay-loader accidentally ripped a hole in an N.N.P.C. underground crude oil pipeline between Owa and Abudu, and so spillingabout 18,818 barrels of crude oil. The spilled oil polluted the nearby River Ossiomo and adjacent farmlands. It was understood that 10 months after the spillage, the affected land still remained infertile and crops dried up.

In summary, the effects of oil spillage are:

1. destruction to soil.
2. destruction of farmland, crops and economic trees.
3. disturbance of human settlement, for example, an oil blowout or spillage, could cause fire which might burn down hamlets and villages.
4. pollution of sources of fresh water for human and animal consumption as in the Abudu incident.
5. destruction and disturbance of marine life such as fish, crabs, water birds and other aquatic animals.
6. rendering canals and waterways that form the highways to the riverine areas, at least, temporarily impassable.
7. contamination of animals, foodcrops, and vegetables, consequently making them unfit for human and animal consumption.

 

(b) Other Pollutants

The pollution of water resources may also be attributed to human misuse. Sources of pollutants include sewage from the homes, dissolved fertilizers from agricultural land; industrial wastes such as phenols and ammonia; and hot water from factories and power stations (thermal pollution).

The release of chemicals into lakes encourages the growth of aquatic organisms (plants and animals) which pile up on the lake bottom; the lake becomes smaller and shallower and eventually turns into a marsh and disappears. Thermal pollution or the release of hot water into rivers and lakes affects the rate of metabolism, respiration, and oxygen demand of aquatic organisms. This causes stress and retards the growth and reproduction of the organisms. Disease causing organisms (parasites, bacteria and viruses) often enter water through pollutants to cause water-borne diseases such as cholera, typhoid, dysentery and schistosomiasis.