The level of some nutrient elements in Abuja surface water were investigated for six months to determine the eutrophication profile and make logical inference on the fate of surface water system in the nearest future. Samplings were done monthly for a period of six months covering October to March and standard methods were used for the measurement of some nutrients constituting the indices of eutrophication. The results showed high levels of microbial activities. Biochemical oxygen demand (BOD) showed high levels of pollution which varied with time and velocity of water current. Other parameters investigated were chemical oxygen demand (COD), nitrate concentration, total dissolved solid (TDS), conductivity, algae count, temperature, pH, phosphate and potassium concentrations. Maximum and minimum values of some eutrophication parameters in the sites were recorded as follows: BOD ( Orozo 38mg/L- 7.37mg/L, Gidan Mangoro 31.2mg/L- 5.08mg/L, Nyanya 32.4mg/L- 10.05mg/L, Wuse 40.30mg/L- 7.007mg/L, Jabi 26.50mg/L- 3.10mg/L). Similarly total dissolved solid maximum and minimum values in the sites were given as Orozo 1222mg/L- 105.1mg/L, Gidan Mangoro 861.0mg/L-148.8mg/L, Nyanya 676.0mg/L- 127.6mg/L, Wuse 200.0mg/L- 86.2mg/L, Jabi 846.0mg/L-151.8mg/L. These results point to eutrophication indicators in Abuja surface water system. The results showed that the concentrations of nitrogen, phosphorus and potassium may be significantly increased beyond their compensation level by the growing human population in Abuja metropolis.
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Table of Contents
Abbreviations, Definitions and Symbols
1.1 Causes of Eutrophication
1.1.1 Natural sources
1.1.2 Anthropogenic sources
1.2 Statement of Problem
1.3 Aims And Objectives
2.0 LITERATURE REVIEW
2.1 Factors Controlling Eutrophication
2.1.1 Algal bloom
2.1.2 Organic manure application
2.1.3 Water hyacinth invasion
2.1.4 Impact of erosion
2.2 Approaches to Controlling Eutrophication and Water Loss
2.2.1 Nutrient control
2.3 Urbanization and Eutrophication Profile
3.0 MATERIALS AND METHODS
3.1 Sampling Sites
3.2 Sample Collection and Preservation
3.3 Measurement of Physical Parameters
3.3.2 Measurement of total dissolved solid
3.3.3 Measurement of conductivity
3.3.4 Measurement of chemical oxygen demand (Titrimetric method)
3.3.5 Measurement of pH
3.3.6 Measurement of biological oxygen demand (Titrimetric method)
3.3.7 Measurement of potassium
3.3.8 Determination of nitrate (Colorimetric method)
3.3.9 Determination of phosphate
3.4 Principles of Operation of Colorimeter DR/890
5.1 BOD Concentrations
5.3 Total Dissolved Solid
5.4 Chemical Oxygen Demand
5.7 Algae Count
5.8 pH Level
6.0 SUMMARY AND CONCLUSION
Eutrophication is the natural process whereby a confined water body (e.g. lake or dam) ages with time due to accumulation of silt or organic matter in the lake (Ademoroti, 1996).
A young lake is characterized by low nutrient level and consequently low plant productivity and at this stage is described as oligotrophic (few food) lake. The water body gradually acquires inorganic and organic nutrient from catchment areas and these promote aquatic growth and increased biological productivity causing the lake to become murky with decaying organic matter and phytoplankton. The water body is said to be eutrophic (well fed) and consequently, the decaying organic matter depletes its available oxygen. Increase in the accumulation of silt and organic matter, makes the water body shallower and sunlight penetrate slowly to the bottom, making the water warmer. Plants take roots along the shallow edges and the lake slowly transforms into a marsh or swamp which may eventually lead to dry land (Ademoroti, 1996).
Anthropogenic impact and seasonal climatic changes have aggravated eutrophication in water bodies worldwide. Advancement in science and technological innovation in agricultural practices has resulted in increased usage of natural and synthetic manures rich in phosphorus, potassium, and calcium in farming. These have accelerated the natural process of eutrophication worldwide. Nations of the world are conscious of the famous Malthusian economic theory and hence fight against this detrimental prediction by increasing food production through the construction of dams for irrigation and energy. Nations in arid regions are also making efforts to conserve their existing water resources to meet the increasing food demand through water storage reservoirs to conserve and harness this precious resource more efficiently. Such reservoirs and lakes are subject to several kinds of degradation and losses through evaporation, inefficient storage and consumption waste in addition to the growth of all kinds of aquatic organisms such as plankton, insects, fish and angiosperms. These changes lead to the phenomenon of eutrophication (Rashid and Anjum, 1985).
Eutrophication therefore causes progressive deterioration of water quality especially lakes due to luxuriant growth of plants with the effect that the overall metabolism of the water is affected (Richard, 1970).
A research carried out by Rashid and Anjum (1985) showed that the presence of Euglena, oscillatoria and Anabaena Spp indicate high organic pollution responsible for eutrophication and this affects the species of microinvertebrates and macrovertebrates including the species of fish in the water. It was found that the predatory specie Notopterus hotopterus was gradually increasing causing threat to the survival of some useful fish in the water body. Eutrophication is therefore detrimental to crop production, fish farming and provision of portable drinking water.
Eutrophic water bodies receive large amount of aquatic plant nutrients relative to their surface area and volume and have high production of aquatic plants (Fred and Ann, 1978). Oligotrophic water bodies tend to be poorly fertilized and have low aquatic plant production, mesotrophic water bodies receive moderate amount of aquatic plants nutrients.
Thermocline is a term used in describing the depth in a water body in which there is rapid change in temperature with depth as a result of the division of the water body into layers with different densities (Fred and Ann 1978). These are the epilimnion the warmer and less dense surface waters and also the hypolimnion which describes the cooler, more dense bottom waters. The thermocline provides a barrier of mixing water between these two layers and is normally present between early June to October in temperate water bodies (Fred and Ann 1978). During this thermal stratification, waters of the hypolimnion are isolated from the atmosphere by the thermocline and cannot replenish their oxygen. Algae which have grown in this area died and decomposed leading to reduction of oxygen at the bottom. In many eutrophic waters, this depletion is sufficient to cause anoxic conditions (Zero dissolved oxygen) in the hypolimnion (Fred and Ann 1978; Muir, 2001).
It was discovered that the river Jordan which is currently the largest and longest river that flows into Israel was under threat of extinction following eutrophication. Adequate measures were taken to keep it alive for utility and consumption since major rivers in Israel were contaminated by agriculture and industrial wastes which made the Jordan River the only natural and clean river in the country (Shoshana, 2012). Biodiversity of algal communities in the upper Jordan River formed as a result of natural climatic and anthropogenic impact was used to predict the disastrous outcome
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