Assessment of Eutrophication Level of Municipal Surface Water, Abuja Nigeria
CHAPTER ONE
AIMS AND OBJECTIVES
The aim of this research work is assess eutrophication parameters in surface water bodies in Abuja.
The objectives include among others to;
- Establish the physicochemical parameters of the surface water of the selected sites.
- Determine the nutritional level of the surface water using standard methods.
- Investigate the level of algal bloom in the selected sites.
- Correlate the algal bloom with nutritional level of the water bodies.
CHAPTER TWO
LITERATURE REVIEW
Eutrophication is a natural process that may take many years. These years can be shortened by anthropogenic activities leading to a rapid eutrophication process with detrimental effects on the man and animals.
FACTORS CONTROLLING EUTROPHICATION
Availability of sunlight and nutrient are factors controlling eutrophication. Sunlight and nutrient stimulate photosynthetic reactions, algal bloom and vegetative productivity. The amount of sunlight available in a water body is proportional to the transparency of the water which in turn is a function of the level of eutrophication (Ademoroti, 1996). An eutrophic lake may become so murky that photosynthesis can only take place at the surface and the top layer (eutrophic zone) where plants grow and produce more oxygen by photosynthesis than they can remove by respiration. The lower zone is called the profundal zone. The transition between these two zones is termed the light compensation level (Ademoroti 1996).
Algal can undergo photosynthesis, multiply and cause odourous clumps of rotten debris when they decay. This clumps of rotten debris is biodegradable by bacteria to cause oxygen depletion which is detrimental to the survival of fishes especially those who live in colder regions at the bottom. Under this anaerobic condition hydrogen sulphide is formed and metals such as iron and manganese tied up as sediments dissolve and are released into the lake (Ademoroti, 1996).
Nutrient enrichment by human and agricultural activities cause cultural eutrophication hence nutrient enrichment control can be used to control eutrophication. Justus Liebig in 1840 developed the idea that the growth of plant is dependent on the amount of food stuff that is presented to it in minimum quantity (Ademoroti, 1996). This implies that algal growth will be limited by the nutrient that is least available relative to its needs hence eutrophication can be controlled by identifying limiting nutrients and reduce its concentration. Liebig’s law deduces that reduction in non-limiting nutrient will not provide effective control unless its concentration is reduce to the point where it becomes a limiting nutrient. If a lake is known to be nitrogen limited, reduction of phosphorus loading will have no effect and vice versa (Ademoroti, 1996).
Algal Bloom
Algal bloom is a term used in describing the rapid increase or accumulation in the population of algae (typically microscopic) in an aquatic system (Van-Dolah, 2000). Algal bloom may occur in fresh water as well as marine environment and usually a small number of phytoplankton species are involved leading to discoloration from high density of pigmented cells. Algal blooms are often green but they can also be other colors such as yellow- brown or red depending on the species of algae. In eutrophic lakes where the dominant species of algae are often blue-green which can obtain nitrogen directly from the atmosphere, the only practical method to control its growth is to focus on phosphorus removal (Ademoroti, 1996).
CHAPTER THREE
MATERIALS AND METHODS
Samples were collected in 2000cm3, 1000cm3 and 500cm3 containers at various strategic sites. The samples were collected in clean plastic containers, acidified with HCl (conc.) and stored at temperatures less than four degree Celsius to inhibit undesirable reactions that may interfere with the analytical accuracy.
The samples for algae count were preserved using Lugol solution which was made by mixing 20 g of potassium iodide with 200 cm3 distilled water then dissolving 10 g of pure iodine in this solution. 20 g of glacial acetic acid was added few days before usage. The solution was stored in dark glass bottle and could remain effective for at least 12 months.
All other samples for biological oxygen demand analysis were not acidified to keep the organisms alive for proper analysis. Glass containers were avoided because potassium can be adsorbed unto the surface thereby producing a lower concentration during analysis.
CHAPTER FOUR
RESULTS
CHAPTER FIVE
DISCUSSION
BOD CONCENTRATIONS
Biochemical oxygen demand is the amount of oxygen required by bacteria for breaking down to simpler substances, the decomposable organic matter present in any water, waste water or treated effluent. BOD can be used to evaluate the concentration of organic matter present in that kind of sample. This is generally carried out by measuring the amount of dissolved oxygen present in any given sample before and after incubation in the dark at 20 degree celsius for five days. High BOD value is proportional to high eutrophication.
CHAPTER SIX
SUMMARY AND CONCLUSION
Physical, Chemical and biochemical parameters were measured in five strategic areas of water channels in Abuja to evaluate the level of eutrophication impact and the physical parameters measured included total dissolved solid and temperature, chemical parameters were concentration of nitrate, phosphate, potassium, conductivity and chemical oxygen demand while biochemical parameters measured were biochemical oxygen demand and algae count.
Based on the findings of this research work, the following recommendations are made.
Periodic assessment of eutrophication levels should be made, recorded and archived for future date references and this should embrace other parameters such as the concentrations of magnesium, calcium, sodium and other trace elements and ions that take part in plant metabolism.
The degree and pattern of rainfall should be monitored in conjunction with eutrophication parameters mentioned above and this should be done simultaneously in a rain forest region of Nigeria and a relatively low rainfall region in the interior Northern Nigeria and the data obtained should be used to access the mitigation of land degradation or Sahara desert encroachment.
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