Heavy Metals in Fish: Bioaccumulation and Health (Published)
Heavy metals occur during natural processes and are also obtained during anthropogenic activities. Heavy metals include chromium, cadmium, arsenic, lead, zinc, nickel, mercury, selenium and copper hence their presence in the aquatic habitat are highly toxic to fishes and shell fishes. Heavy metals are found in the aquatic environment as a result from contamination by heavy metals from industrial, agricultural waste and by-products and domestic waste and by products. The increasing level of heavy metals in fish is alarming and has spurred scientists to make researches on the dangers caused by the heavy metals resulting to heavy metal accumulation and bioaccumulation of life cells. The aim of this study was to assess the possible sources of heavy metal in the aquatic environment, impact of heavy metals in the aquatic environment, its bioaccumulation in fish and human health impact. Several reports tell of the detrimental effect of heavy metals in fish (some of which include; poisonous effect in the blood such as anemia, eosinophilia, lymphocytosis, renal lesions, convulsions and ataxia, detachment of gills, fusion of secondary gill filaments, acute inflammation in the liver, amongst several others) and in man (some of which include, skin diseases, Irritation of the gastrointestinal mucosa, nephritis, lung cancer, liver and kidney damage, necrosis, neurological and behavioral disorders and death amongst others). In conclusion, the toxic effects of heavy metals in fish and the effect of bioaccumulation and bio-magnification have been reviewed in this paper. It is therefore recommended that the treatment of all forms of wastewaters, agricultural waste, sewage, industrial effluents be carried out before their discharge in to the environment. Also, the enforcement of all laws, legislations regarding the protection of aquatic life and environment should be enforced and sanctions meted out against defaulters.
Pb, Zn, Cu, Ni And Co Contents of Water and Sediments, in Relation to Phytoremediation and Translocation by Water Hyacinth (Eichhornia Crassipes Mart. Solms.) At Some Creeks of the Great Kwa River, Southeastern Nigeria (Published)
A passive phytoremediation study to investigate the environmental purification efficacy of water hyacinth (Eichhornia crassipes) was carried out at Mbat-Abiati and Oberekkai Creeks of the Great Kwa River in Southeastern Nigeria. The study assessed the levels of Pb, Zn, Cu, Ni and Co in the water column and underlying sediments (abiotic monitors) in comparison with their levels in E. crassipes (biomonitor). Generally, observed values of heavy metals in sediment and water hyacinth of the two Creeks did not vary significantly (p>0.05), and the sequence that was frequently encountered in the accumulation of the heavy metals was: SEDIMENT>PLANT ROOTS>PLANT LEAVES>WATER. Relative Accumulation Indices (RAI) revealed that the concentration of the heavy metals in the sediments are much higher than values recorded for the waters. This appear normal since sediments are reservoirs for all contaminants and dead organic matter descending from the ecosystem above. The pattern of heavy metal concentrations in the organs of E. crassipes are closely associated with that of its geological substrate (water and sediments). Although zinc displayed the highest accumulation in both root and leaves tissues, and appeared more mobile from roots to leaves than other heavy metal, the bioconcentration factor (BCF) revealed Co as the metal with the highest phytoaccumulation capability in the area, followed by Ni, Cu, Pb and Zn, in that order. Indication from the study is that water hyacinth (Eichhornia crassipes) can effectively absorb and translocate Pb, Zn, Cu, Ni and Co, even when the concentrations of the metals in the abiotic components of the environment is low.
Assessment of Selected Heavy Metal Residues in the Kidney, Liver, Muscle and Gizzard of Chickens Raised Within Enugu Metropolis (Published)
Studies were carried out for possible bioaccumulation of the following heavy metals; Pb, As, Cd, Cr, Hg, Ni, V and Cu in the internal parts (kidney, liver, gizzard and muscle) of twenty seven (27) local and exotic chickens raised within Enugu metropolis after wet digestion of samples and subsequent use of atomic absorption spectrometer. All the selected heavy metals were found to be present in the studied parts of the chickens although at concentrations within their respective established permissible limits for meats consumption. The internal organs of experimental chickens accumulated heavy metals in the following increasing order: liver > kidney > gizzard > muscle. Except vanadium, the concentrations of all other metals in the studied parts of the chickens showed significance at p < 0.05 from the anova analysis. The mean concentrations of Pb, Cd and Hg were very much higher in the kidney and liver the chickens than other studied metals. The experimental chickens accumulated heavy metals in the following increasing order: local chicken > layer chicken > broiler chickens.