EFFECT OF CRUDE OIL POLLUTION ON DISSOLVED OXYGEN AND PH IN AQUATIC ECOSYSTEM
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND TO THE STUDY
Pollution is defined as the release of toxic or harmful substances into the environment (air, water and land) by their natural forces or man and other animals to an extent that cause biological damage to man and his resources. The harmful substances that cause pollution to the environment are called pollutants ( Eshagberi, 2014). There are six main types of pollution, these are; Air pollution, noise pollution, land pollution, water pollution, thermal pollution and nuclear pollution. AIR POLLUTION – This is defined as the presence in the atmosphere (indoor or outdoor) one or more air contaminants (dust, fumes, gases, mist, odour, smoke, noise, particles or vapour) in sufficient quantities, of characteristics and duration, as to be or threatened to be injurious to human, plant or animal life or to properties or which reasonably interfere with a comfortable enjoyment of life or property (World Bank, 2005). NOISE POLLUTION – This refers to any unwanted sound that affect our health. The unit of noise is decibel. Noise pollution encompasses roadway noise, aircraft noise, industrial noise, noise from generator, high pitched music e.t.c LAND POLLUTION – Is any process carried out by man that leads to an adverse change in terrestrial environment. There are a number of sources of land pollution. These include; refuse, sewage, metal scraps, pesticides or fertilizers, chemicals glass particles, crude oil spillage. THERMAL POLLUTION – This is a form of pollution that involves the raising or lowering of air or water temperature above or below normal seasonal ranges in streams, lakes or estuaries or oceans as the result of discharge of hot or cold effluents into such water or atmosphere. The main cause of thermal pollution is the use of water as a coolant especially in power plants. Water used as coolant is returned to the natural environment at a higher temperature. Increase in water temperature can alter aquatic organisms’ lives by decreasing oxygen supply, kill juvenile fish which are vulnerable to small increase in temperature and also affect ecosystem composition. NUCLEAR POLLUTION – This refers to the release of radioactive materials into the environment. Major source of radioactive pollution include nuclear power plants, nuclear weapon, transportation, disposal of nuclear waste, uranium mining. WATER POLLUTION – This refers to the release of toxic materials, agents of pollution into water bodies. Until recently, water pollution has been a relatively local problem of the developed world. Eutrophication is the most common problem where inland waters and rivers are polluted with nitrogen and phosphorus run-off from fertilizers used in intensive agriculture and discharge of phosphate-rich sewage effluents. Such problems are increasingly occurring on a worldwide basis and now affect marine as well as freshwater ecosystem (Eshagberi, 2014). Sewage from coastal settlement discharges, sometimes untreated, into coastal waters where it generates a direct health hazard for recreational bathers as well as marine organisms. Land drainage from urban areas, industrial and waste disposal site is often contaminated with heavy metals or hydrocarbons.
