Industrialization, urbanization and population explosion have caused a high rate of waste generation in Nigeria. Chemical wastes in water include dissolve metals and their salts, acids, bases, and inorganic compounds, solvents and solutions, etc. The effluents from the industries may include fluorine, waste water, heavy metals, dyes, colorants, esters and alcohols. The pollution potential of these effluents depends on the nature of industries around the water body (Phiri et al., 2005). These chemicals include nutrients comprising nitrates and phosphates derived from municipal waste waters which are inorganic nutrients that promote plant and algae growth, which have detrimental effects on rivers and lakes; algae can be toxic to cattle and spoil the taste of water (Esoka and Umaru, 2006). Waste liquids from textile industries due to dye stuff, sulphates, sulphides, copper, zinc lead, phenolics and wastes from the manufacture of pulp and paper contain sulphides, chlorides, lingocellulozic wastes, metercapenes and mercury etc. Canals are highly polluted by sewage disposals from hotels, hospitals, houses and municipal wastes. Of much concern are those wastes that resist bio-degradation but enter the aquatic and human systems. Heavy metals can affect the aquatic organisms as toxic substances in water and sediment or as a toxicant in the food chain (Zyadah and Abdel-Baky, 2000). It was discovered in a study that fish can bioaccumulate heavy metals from a polluted environment and could be a risk factor for accumulation of heavy metal in humans after a long time that would lead to dangerous diseases.
49 2.4.6 Chemicals and Petroleum Products
Underground and aboveground storage tanks are commonly used to store petroleum products and other chemical substances. Crude or refined oil products spill or accidental discharge or the disposal of used or exhausted lubricants and waste oils, have detrimental effects on the environment mostly on the aquatic life. These results mostly from equipment failure or during transfer operations as between ships and shore. Wherever spillage takes place, the more volatile components of the spill is evaporated into the atmosphere while the more dense parts sink to bottom of the sea and settle with the sea sediments. If an underground storage tank develops a leak, which commonly occurs as the tank ages and corrodes, its contents can migrate through the soil and reach the ground water (Ground water, 2002).
A correlation exists between exposures to oil spillage and development of health problems. A study examined the effects of environmental degradation on human health in nine selected oil communities in Delta State, Nigeria. Water samples collected from sea, rivers, streams, boreholes, and lagoons from Niger Delta contain benzo − pyrene at concentrations above WHO permissible limits. The consumption of fish, vegetables and other aquatic food from such locations are prone to bioaccumulation of the respective heavy metals with incidence of cancer risk being high (Atubi, 2015). Local communities within oil producing countries in Africa often face formidable environmental challenges that generate conflicts and concerns around exploitation, environmental impact, and health risks (Adekola et al., 2016). In Nigeria, palm oilmill effluents are discharged directly and untreated into the nearby agricultural lands and surface waters in its raw form especially by small scale processors. This may also contribute significantly to the pollution load of the river and affect the quality of the river for other uses (Josephine Edwards et al., 2016).
50 2.4.7: Agricultural Debris in Water
These arise from three sources, thus animal rearing practices, fishing and farming. In farming, herbicides, fungicides, insecticides and fertilizers are made use of and are subsequently transported to the surface and ground water. These constitute a treat to aquatic life and all forms of life that depend on water. Contamination by pesticides, phosphates and insecticides that drain off to streams and rivers by runoff or leached into the ground water are toxic to man. The Kepone group of insecticides are potential hazards encompassing a variety of chemicals such as morex, aldrin, dieldrin and heptachlor, when drained off to streams and rivers by runoff or leached into the ground water, poses potential poisons to aquatic life. Abnormalities in cell growth, many liver lesions and cancer have been attributed to contamination of water by kepone. These insecticides on reaching the coastal water result in death of fishes. The following chemicals above 0.1ppm in water can be lethal to some fish, such chemicals as DDT, endrin, heptachlor, parathion, malathion. Plants growing in metal-polluted sites exhibit altered metabolism, growth reduction, lower biomass production and metal accumulation. Various physiological and biochemical processes in plants are affected by metals (Nagajyoti and Sreekanth, 2010).
Other debris in water includes phenols, tannins, nitrates, dioxins, sulphates, phosphates and cyanides. Dioxin is lethal to man. Polar compounds are believed to penetrate cell membranes through protein filaments; while non-polar compounds enter through lipid matrix. Electrolytes (HCl, H2SO4 , NH4Cl, NaSO4) enter mainly in the non-ionized form and thus the pH of the solution applied to the skin affects the permeability.
Some chemicals found in the environment such as carbon Tetrachloride (CCl4 ), and organophosphate insecticides found in water and the environ penetrate the skin
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(stratum corneum). Organo- phosphate insecticides are organic compounds that contain phosphorus ,most of which are organic derivatives of ortho-phosphoric acid. Some of the organo-phosphate insecticides are esters of phosphoric acid. Toxicity of ortho-phosphate insecticides vary, as little as 120.0 mg has been known to kill a man, while 20.0 mg has killed a child. Most accidental poisoning had been through the skin. It is a systematic poison; that is one that is transported through the body to sites remote from its entry site. The organo-phosphate compounds produced as industrial poisons are deadly in minute quantities ( known as nerve gases). Tri methyl phosphate is moderate in toxicity when taken in, but Tri-ethyl phosphate (C2H5O)3PO, damages nerves and inhibits acetylcholinesterase. tri-o-cresylphosphate in the water body is noxiously toxic and exposure causes degradation of the neurons in the body’s central and peripheral nervous system with early symptoms of vomiting, diarrhea and nausea which leads to partial or complete paralysis. The carbonates are pesticides widely used as insecticides on lawns or gardens. Carbo-furan has a high water solubility and acts as plant systemic insecticide which when taken up by plant roots and leaves, the insects are poisoned by the plant material on which they feed. It has a strong tendency to bind to soil and sediments. They are toxic to animals as they inhibit the formation of actyl cholinesterase without undergoing bio−transformation first and are taken as direct inhibitors. Polychlorinated Bi-phenyls (PCB) have been found world over in water, sediments, bird and fish tissues. The dumping of PCBs’ on the rivers and riversides, being virtually insoluble, dense, hydrophobic materials accumulate in the rivers’ sediments, causing serious concern as a result of their bio-accumulation in fish. Heavy metals are normal constituents of marine environment that occur as a result of pollution principally due to the discharge of untreated wastes into rivers by many industries (Wang et al., 2010.). Bioaccumulation of heavy metals
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in tissues of marine organisms has been identified as an indirect measure of the abundance and availability of metals in the marine environment (Babatunde et al; 2012).
The concern for the environment in and around the Aba River is neither new nor is it isolated in the study of science and environment. In some of the studies the actions of the host community to the environment and workers in it sparked off such, while in some others as this, observations of the local scenario prompted the research. In this research physical and physicochemical parameters, heavy metals, sediment and plant tissues (leaf, stem and root) in the water body, were investigated.
The environment have never been cared for though it sheltered all that is alive on the planet Earth and have suffered from anthropogenic activities of man which tends to destroy or sacrifice the environment on our table of uncontrolled industrialization, urbanization and plan-less economy of today. The determination of traces of heavy metals in the natural waters, plant parts and sediments plays important role in the aquatic environment hence giving vital information on the pollution status of the river.