Background Of The Study
Orogodo River is one of the numerous freshwater bodies that abound in the Niger Delta area of southern Nigeria. It is a typical municipal stream flowing through Agbor town with a pollution of over 100,000 people (Arimoroet al., 2008). The river is subjected to organic pollution load arising from the effluent discharge from the abattoirs stations along the river bank, which comprises of stomach and intestinal contents of slaughtered animals, ashes of burnt animals’ materials that are slaughtered daily that makes up an enormous volume of waste discharge regularly into the stream without treatment. Furthermore, the river is influenced by frequent disturbance from human and animal activities which if not properly managed can pose severe health risk to the populace. There is need to assess the level of heavy metal contamination in Nigeria water sediments and also see the effect of these contamination to the aquatic life and ecosystem in general. It is widely recognized that marine ecosystems can become contaminated by trace of metals from numerous and diverse sources. However, anthropogenic activities, such as mining and industrial processing of ores and metals, still remain the principal cause of the increase amount of heavy metals which have been dumped in to the oceans (DeGregori et al., 1996). Heavy metals belong to the group of elements whose hydro-geochemistry cycles have been greatly accelerated by man. Anthropogenic metals emission into the atmosphere such as Pb, Hg, Zn, Cd and Cu are 1:3 orders of magnitude higher than natural fluxes. As a consequence, these elements are expected to become increasingly accumulated in natural reservoirs.
Protecting sediment quality is an important part of restoring and monitoring the biological integrity of our Nation’s water as well as protecting aquatic life, wild life and human health. Sediment is an integral component of aquatic ecosystem providing habitat, feeding, spawning and rearing areas for many aquatic organisms. Sediment also serves as reservoir for pollutants and therefore a potential source of pollutantsto the water column, organisms, and ultimately human consumers of those organisms. Contaminated sediment can cause lethal and sub-lethal effect in benthic and other sediment associated organisms (US EPA 2001). Also natural and human disturbances can release pollutants to the overlying water, where pelagic (water column) organisms can be exposed. Sediment pollutants can reduce or eliminate species of recreational, commercial or ecological importance, either through direct effects or by affecting the food supply which the sustainable population requires. The extent and severity of sediment contamination in U.S has been documented in the National Sediment Inventory (NSI). The evaluation of sediment contamination data indicates that thousands of locations have been affected throughout the country (US EPA2001).This work covers sampling of whole sediment and analysis to ascertain the level of contamination of heavy metals in River Orogodo.
Orogodo River has potential for pollution arising from anthropogenic activities like all major rivers passing through densely populated and built environments. The river is subjected to organic pollution load arising from the effluent discharge from the abattoirs stations along the river bank, which comprises of stomach and intestinal contents of slaughtered animals, ashes of burnt animals’ materials that are slaughtered daily that makes up an enormous volume of waste discharge regularly into the stream without treatment. Furthermore, the river is influenced by frequent disturbance from human and animal activities which if not properly managed can pose severe health risk to the populace. There is need to assess the level of heavy metal contamination in Nigeria water sediments and also see the effect of these contamination to the aquatic life and ecosystem in general.
The aim of this project work is to determine heavy metals in some selected location in Orogodo River, Delta state, Nigeria.
· The objective of this work is to ascertain the level of heavy metals in analyzed samples.
· To determine the concentration of heavy metals in the selected locations of the Orogodo river.
· To evaluate the impact of the abattoir effluent discharge on the river and consequently, the risk posed to public health as a result of the identified pollution.
· Compare the concentrations to known standards
The scope of this study covers the sampling exercise, field study, a laboratory analysis of samples obtained and interpretation of laboratory data using statistical, graphical illustration. The field study was carried out along the course of the Orogodo River, taking the abattoir discharges point as the source. Sediment was collected using the grab sampler from some specific point of the river both upstream and downstream discharges from the abattoir.
In small quantities, certain heavy metals are nutritionally essential for a healthy life. Diagnostic medical application includes direct injection of gallium during radio logical procedures dosing with chromium in parent nutrition mixtures, and the use of lead as x-ray shield (Jassir, M.S., et al, 2005). Heavy metals are also common in industrial applications such as the manufacture of pesticides, batteries, alloys, electroplated metal parts, textile dyes, steel, and so forth (WHO, 2006). Many of these products are in our homes and add to the quality of life when properly used. In biological systems, heavy metals have been reported to affect cellular organelles and components such as cell membrane, mitochondrial, lysosome, endoplasmic reticulum, nuclei, and some enzymes involved in metabolism, detoxification, and damage repair. Metal ions have been found to interact with cell components such as DNA and nuclear proteins, causing DNA damage and conformational changes that may lead to cell cycle modulation, carcinogenesis or apoptosis. Several studies from our laboratory have demonstrated that reactive oxygen species (ROS) production and oxidative stress play a key role in the toxicity and carcinogenicity of metals such as arsenic,cadmium,chromium, lead, and mercury. Because of their high degree of toxicity, these five elements rank among the priority metals that are of great public health significance. They are all systemic toxicants that are known to induce multiple organ damage, even at lower levels of exposure. According to the United States Environmental Protection Agency (U.S. EPA), and the International Agency for Research on Cancer (IARC), these metals are also classified as either “known” or “probable” human carcinogens based on epidemiological and experimental studies showing an association between exposure and cancer incidence in humans and animals. Heavy metal-induced toxicity and carcinogenicity involves many mechanistic aspects, some of which are not clearly elucidated or understood. However, each metal is known to have unique features and physic-chemical properties that confer to its specific toxicological mechanisms of action.
This study was carried out to examine heavy metals concentration in sediment of upstream and downstream of the entry of the sewage to the Orogodo River, Agbor, Delta state Nigeria . Samples were collected from upstream and downstream and were analyzed for Heavy metals (Cd, Cr, Cu, Fe, Pb, Ni, Ca, Mg, Co, Mn and Zn) by atomic absorption spectrophotometer. It shows the concentration of iron, cadmium, manganese, cobalt, chromium, zinc, magnesium, calcium, nickel, lead and copper in mg/kg in sediments sampled.Some specific physico-chemical characteristics, such as TDS, pH, Temperature and conductivity which are known to influence the interactions and dynamics of metals within the sediment. The mean value of the metals listed above in all the six locations gave 126.09mg/kg, 0.000mg/kg, 0.538mg/kg, 0.000mg/kg, 0.141mg/kg, 1.789mg/kg, 1.258mg/kg, 9.49mg/kg, 0.000mg/kg, 0.112mg/kg and 0.0827mg/kg respectively.. The result of the analysis It shown that the concentrations of heavy metal like Zn, Pb, Cr, Ca, Cu, Co, Mg, Mn, Cd and Ni in the sediment are low, but require monitoring to prevent an increase. Hence the concentration of Fe is higher when compared with the WHO and FEPA standard for sediment which may constitute risk to the environment. The concentration of heavy metal varies for the different locations. Based on the result of analysis, recommendation were offered to reduce the concentration of heavy metal of the river.