Assessment of Heavy Metals and Polycyclic Aromatic Hydrocarbons in Water, Fish and Sediments of Rivers Niger and Benue Confluence, in Lokoja, Kogi State, Central Nigeria
CHAPTER ONE
Objectives of the Research
The aim of this research study is to ascertain the level of pollution of the confluence of rivers, Niger and Benue, and the objectives are as follows: to
- Evaluate the levels of PAHs in water, fish and sediments samples from the rivers confluence.
- Assess the total levels of Heavy Metals in the water, sediments and fish samples selected.
- Determine Transfer factor (TF) of HMs from sediment to fish and therefore determine the bioaccumulation of the pollutants.
- Assess the possible health hazard posed by ingestion of fish and use of the river waters studied
- Determine the ecological risk index (ERI), Index of geo-accumulation, Contamination factor and Pollution load index posed by the heavy metals in the sediments and
- Compare the results with the set standards for water and fish by regulatory agencies.
CHAPTER TWO
LITERATURE REVIEW
General Overview
Sediments have been reported to be an important sink and repository for heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) emitted from natural and anthropogenic sources as well as potential non-point pollution sources which may directly affect overlying waters and aquatic organisms43,44. The concentration of heavy metals depends on the amount of heavy metal waste entering the waters. The more the waste entering the water, the higher the concentration found in the water. The heavy metals which enter water body will undergo sedimentation, dilution, dispersion, and then they will be absorbed by the organisms living in the water and the heavy metals which settles at the bottom will be stored in the sediment44. Therefore, the profile of trace contaminants in undisturbed sediment cores can be utilized to estimate the extent and history of pollution in aquatic environment45-47. Apart from sediments, river water and even the aquatic animals (Fishes) have been used to determine pollution in the environment in order to assess the impact of pollution in the surrounding environment48-50. The chemical contaminants causing toxicity in aquatic environment and aquatic animals as a result of their accumulation, high stability and non-degradable or non-biodegradable nature include among others, heavy metals and polycyclic aromatic hydrocarbons (PAHs)30. Therefore, this research work and particularly, this literature review is aimed at discussing the sources of heavy metals and polycyclic aromatic hydrocarbons as well as the impact of these two hazardous pollutants (Heavy metals and polycyclic aromatic hydrocarbons) on the aquatic organism and by implication man who depends on the aquatic organisms for survival. In addition, a brief discussion on the principles behind the operation of the techniques used to determine this pollutants namely Atomic Absorption spectrophotometry for the heavy metals determination and Gas Chromatography for the PAHs determination were established respectively.
Heavy Metals
The term heavy metals have been previously defined as members of a 1osely defined subset of elements that have density above 4.0 gcm-3; exhibiting metallic properties and can be chemically toxic to plants and animals which include: Hg, Pb, Fe, Cd, Cu, As, Tl, Mn, Ni, V and Se20-23. In natural environments, they occur at low concentrations but at high concentrations in contaminated environments, where they impact on public health.
Heavy metals are released into the environment from metal smelting and refining industries, scrap metals, plastic and rubber industries, various consumer products and from burning of waste containing these elements. The metals volatilize on burning and is released into the air. These volatilized metals becomes mobile and travels for large distances and are deposited on the soil, vegetation and water depending on their density. Once deposited, the metals are not degradable, they persist in the environment for many years poisoning humans through inhalation, ingestion and skin absorption. Acute exposure to these toxic metals leads to nausea, anorexia, vomiting, gastrointestinal abnormalities, dermatitis and many fatalities as those that occurred among a fishing community in minamata Bay Japan, due to consumption of fish polluted by methylmecury in 1950, and in Ghana in 1967. In 1968, the Japanes government traced the causes of Itai-Itai disease – a very unusual and painful disease due to chronic cadmium poisoning resulting from consumed poisoned Fish and recently in Nigeria, lead poisoning in Zamfara state killed several children caused by illegal mining activities.
CHAPTER THREE
EXPERIMENTAL
Materials
The following Chemical materials, apparatus and instruments were used during this research work and all chemicals used were of analytical grade. The chemicals used were: Deionized water (H2O), (65%) Nitric acid (HNO3), (30%) Hydrogen Peroxide (H2O2), Hydrochloric acid (HCl), Hydrofluoric acid (HF), Dichloromethane (CH2Cl2) (JHD China), Anhydrous Sodium Sulphate (Na2SO4) (BDH Chemicals, Poole, England), 60-120 mesh Silica gel (Qualikems fine Chemicals, India), Potassium silicate (K2SiO3), Hexane (C6H14) (JHD China), Acetone (CH3COCH3), Standards of the sixteen priority PAHs (New Haven, USA) and Helium gas (Air liquid gas company, France).
The apparatus and instrument used were polyethylene bags and containers, Refrigerator, ice-cooler box, hand trowel, standard flask, plastic knife and plastic sieve, oven, fume cupboard, whatman filter paper, mortar and pestle, weighing balance, conical flask heating mantle or hot plate, Glass funnel, measuring cylinder Rotary vacuum evaporator (Seno technology, China), column chromatographic set, Soxhlet extractor (Quick fit, England), Magnetic stirrer, Porcelain basin, Evaporating dish, Desiccator, AAS (PG-900 and Sensa PS-270), and GC–MS (Agilen 7890, series A, USA)
Description of Study Area
The study area is the confluence of rivers Niger and Benue in Lokoja Kogi State, Central Nigeria. The state lies between the coordinate of latitude 7o30’N/6o42’E and longitude 7.500oN/6.700oE and Lokoja lies between 7o45’N, 7o52’N of the equator and longitude 6o45’E of the Greenwish meridian. Lokoja is bounded in the west by the river Niger at an altitude of 45 – 125 meters above sea level. The climate is tropical wet and dry climate characterized by wet (raining) season between May to October and dry season between December to April, with an annual rainfall of about 1000mm132, 133. Lokoja is the headquarters of Lokoja L.G.A. and the capital of Kogi State, having an area of 3180 km2 land and a population of 196,643 people at the 2006 census with majority of the local indigene involving in farming and fishing.
CHAPTER FOUR
RESULTS AND DISCUSSION
RESULTS OF PHYSICOCHEMICAL PARAMETERS
The physicochemical characteristics of the water of rivers Niger and Benue confluence were determined in situ using hand held probes shown in Table 3.1(Chapter Three) during the dry and rainy season sampling for the determination of heavy metals and polycyclic aromatic hydrocarbons and the results of the physicochemical parameters were as shown in table 4.1 below. The table shows the values of temperature in degree Celsius, electrical conductivity in micro Siemen per centimeter and total dissolved solids in milligram per liter in station A to E.
Results of quality control studies/Recovery Analysis
Analysis of standard reference materials of PAHs (SRM 822-275872-11) and HMs (ASTM D3557 for Cd, D1687 for Cr, D1688 for Cu, D1068 for Fe, D3559 for Pb and D1691 for Zn) were carried out as a measure of analytical quality assurance for the PAHs and HMs sort for in the samples of water, fish and sediments to obtain recovery of the method and to therefore ascertain the accuracy and precision of the method. The recovery of the results obtained ranged from 100.30 to 107.80 for the PAHs and 88.83 to 107.80 for the heavy metals as shown in table 4.2, 4.3 and 4.4 respectively.
CHAPTER FIVE
Conclusion and Recommendation
Health they say is wealth, therefore, man has always tried to know in order to avoid whatever is capable of causing deleterious effect on his health. Notable among the substance with the ability to damage the human health via diverse of human health issues are the heavy metals and PAHs which this research study seeks to evaluate at the outset of this study for the first time in the history of mankind in this research area of study. The research study was design to therefore profile and estimate the concentration of heavy metals and polycyclic aromatic hydrocarbons in the confluence of rivers Niger and Benue water, fish and sediment and to estimate the human health and ecological risk factors. The study has been able to clearly show that the concentration of heavy metals and PAHs in the water, fish and sediments are of moderate risk but begging for immediate attention, therefore good hygiene, measures against indiscriminate dumping of waste in the water as well as burning of tyres, organic and petroleum products that are the major sources of heavy metals and PAHs be ensured with the creation and implementation of stiffer laws to regulate bush burning and refuse disposal. Also, constant routine monitoring should be ensure in order to guide against ignorant consumption of excess pollutants (HMs and PAHs) should the level of the HMs and PAHs in the media increase to intolerable limit.
REFERENCES
- Adefemi, Samuel Ohiyemi, Oyakhilome, Gloria Irenosen, Asaolu, Sunday Samuel, and Aiyesanmi, Admola Festus. (2013) Interrelationship of Heavy Metals Concentration in water, sediment and fish samples from Owena multi- purpose Dam, Ondo state, Southern Nigeria. Emerg. Tren. Engr. Appl.Sci. (JETEAS) 4(2): pp 207 – 215.
- Etim E. E., Ogah E. And Eneji S. I. (2013). Seasonal variation of physicochemical properties of selected Revers in North Central states of Nigeria: J. Modern Anal. Separation sciences, 2(1): pp. 31 – 38.
- UNFPA (United Nations Population Fund (2003). Global Population and water access and Sustainability, Population and Development Strategies Series. New York, NY10017.
- Avishai, N., Rabin OWHZ, C., Moiseeva, E. And Rinkeveh, B. (2002): Genotoxicity of the Kishon River, Israel: The Application of an Invitro. Cellular Assey. Mutation Research, 518: pp: 21 – 37.
- Matsumoto, S. T., Janaina R., Mario, S. M. And Maria, A. M. (2005). Evaluation of the Genotoxic Potential due to the action of an Effluent Contaminated with Chromium, by the Comet Assay in CHO-K1 Caryologia 58(1): pp. 40 – 46.
- Tove Wium – Andersen, Asbjorn Haaning Nielsen, Thorkild Hvitved – Jes Vollertsen (2010). Heavy metals, PAHs and Toxicity in Stormwater wet detention ponds. Novatec 1 – 10.