Assessing Uptake Kinetics and Natural Depuration of Lead and Cadmium in African Catfish Juvenile

This study was carried out to assess the uptake kinetics of two heavy metals lead and cadmium in African catfish juveniles and their ability to  depurate during subsequent exposure to clean water. Catfish juveniles with average weight and length of 5.3g and 5.8cm respectively were  randomly selected and acclimatized for two weeks. A 24-hour range finding test was carried out. In the definite test, the fish were stocked in 24 tanks containing 5litres of water with lead and cadmium treatment separately labeled according to predetermined concentrations 5, 10, 15, 20, 25 mg for lead and cadmium with 4 fish in each treatment. The water and fish were analyzed for the metals after 5 days to show percentage uptake of the metals from the water. The fish were transferred back into clean water to access the rate of depuration and water was changed continuously. After 4 days the fish were analyzed again to see if they were purged of the heavy metals. Based on these findings catfish have shown to be good accumulators of heavy metals but can be depurated if allowed to swim in clean water. Uptake percentage after the period of exposure to 5mg,  10mg, 15mg, 20mg, 25mg concentrations were 18.68, 10.17, 5.95, 1.41, 8.26 for cadmium and 20.47, 10.17, 8.76, 9.92, 10.08 for lead; Percentage of metals depurated after 4 days were 40.00, 80.70, 90.00, 77.78, 45 for cadmium and 73.045, 20.413, 41.425, 37.580, 61.141 for lead. Lead was readily taken but cadmium was readily depurated. Keywords: Heavy metals, juvenile catfish, exposure, uptake and depuratio

Acute toxicity of benzalkonium chloride mixture with treated produced water to juveniles of freshwater tilapia - Oreochromis niloticus

This research was conducted to determine the lethal concentration (LC50) of benzalkonium chloride (BAC) mixture with treated produced water capable of causing mortality of at least 50% of the Nile-tilapia-Oreochromis niloticus juveniles in a static 96h acute toxicity. Juveniles of mix sexes of O. niloticus of average length (6.80 cm) and weight (25.05g) were exposed to various concentrations (20.20, 50.50, 101.00 and 202.00 ppm.) of the toxicant with tap water used as control under laboratory condition. The LC50 values at 24, 48, 72 and 96hours were determined to be 96.427, 73.799, 73.799 and 69.772 ppm, respectively. Water quality check and general fish behaviour (respiratory distress, loss of balance, erratic swimming and death) were observed. Regression equation(y =-0.270 + 93.44) and correlation (R2 = 0.751) obtained from the study depict direct positive relationship between fish mortality and BAC mixture. Hence, unregulated release of benzalkonium chloride and treated produced water into aquatic environment is capable of causing acute toxicity to juveniles of O. niloticus. Its disposal into the environment should therefore be discouraged.Keywords: Acute-toxicity, LC50, Benzalkonium-chloride-mixture, Nile tilapi

Heavy Metal Uptake and Bioaccumulation by Mangrove Grab (Goniopsis pelli) from used Drilling Mud, Niger Delta, Nigeria

This study was carried out to evaluate some heavy metal uptake and bioaccumulation in the meat, egg and shell of G. pelli from used drilling mud. The experimental approach involved the exposure of ten of the test organism G. pelli to six acute concentrations of drilling mud representing 0% (control), 10%, 20%, 30%, 40% and 50% for 96 hours in three replicates after the range finding test was conducted to determine the LC50. From the LC50, the test organism was further exposed to four sub-lethal concentrations of drilling mud (0%, 5%, 10% and 15%) for 21 days to evaluate the heavy metal uptake by the test organism. the result showed that heavy metal uptake increased in the order of meat (<0.001-2.36±0.12), shell (<0.001-3.31±0.19) and egg (<0.001-0.54±0.05) when compared with those in control tank. Copper was highest (3.31μg/g) in the shell and lowest (0.26μg/g) in the egg; zinc was highest (2.36μg/g) in the meat and lowest (0.22μg/g) in the shell; chromium was highest (0.12μg/g) in the meat and lowest (0.06μg/g) in the egg; cadmium was highest (0.2μg/g) in the shell and lowest (0.001μg/g) in the egg while lead had equal value (<0.001) in the meat, shell and egg of the test organism. This could pose a very serious health challenge to the consumers of G. pelli and other aquatic fishery resources if nothing is done to ensure the best practice in drilling activities in other to avoid pollution of the water bodies through drilling. Keywords: Heavy metals, bioaccumulation, drilling mud, Goniopsis pell

Histopathological variations in gills, liver and kidney of nile tilapia - Oreochromis niloticus exposed to benzalkoniumbhloride mixture with treated produced water

The microscopic examination of tissue in order to study the manifestations of disease is very important. This paper investigated the histopathological variation in some organs of juveniles of Nile tilapia-Oreohromis niloticus exposed to benzalkonium chloride (BAC)-treated produced water (TPW) mixture in a 96hour acute toxicity test. Fish specimens of average body length and weight 7.80 cm and 25.05g, respectively were used. At the end of exposure 2 survivor fish in each concentration across triplicates were randomly harvested for the histological examination. Histological preparations of gills, kidney and liver were analysed for histopathological alterations. Results of histological examination revealed various degrees of legions ( gills- cellular necrosis and epithelial rupture (CN), kidney - glomerular expansion (GE) and dilation of Bowman’s space (BC) and liver - expanded central vein (CV) and melanomacrophages aggregate (M)) depending on concentrations of the toxicant as against untreated (control) that recorded no abnormality. The results showed that the severity of tissue alterations recorded was a function of toxicity ofbenzalkonium chloride (BAC) mixture with treated produced water (TPW). It is strongly recommended its disposal followed a thorough treatment.Keywords: Benzalkonium-chloride, treated-produced-water, histopathology, cellular necrosis, O. niloticu

Tissue Distribution and Bioavailability of Trace Elements in Ergeria Radiata from the Upper Reaches of the Nun River, Niger Delta, Nigeria

Fresh samples of the clam Ergeria radiata were collected at six stations spanning 50 km along the upper reaches of the Nun River, Niger Delta, Nigeria. The animals were dissected into the foot, gills, viscera and shell and digested separately according to standard methods.  Selected trace elements (PZn, Cu, Cd, Pb, Cr, and Ni) were analysed in each category to delineate the portioning of the elements in the organism

Assessment of Human Health Risk from Heavy Metal Loads in Freshwater Clam, Ergeria radiata, from the Nun River, Niger Delta, Nigeria

The Nun River where the present study took place is one of the two arms of River Niger system traversing Bayelsa State, Nigeria before emptying into the Atlantic Ocean. It is home to a number of commercial fish and shellfish species, some of which are endemic, including the highly relished freshwater clam (Ergeria radiata) in the Niger Delta region of Nigeria. The Nun River is subjected to a myriad of human induced contaminations from oil and gas activities, agricultural runoffs, sewage disposal and recently illegal oil refining activities. Six stations were selected along the upper reaches of the Nun River across six communities spanning over 50 km. Water, sediment and E. radiata samples were collected during the months of August, October, December and January at the established stations.  Trace metal (Pb, Cr, Cu, Ni, Cd and Zn) levels, bioaccumulation and bioavailability potentials of the metals in the clam were evaluated. The heavy metal levels were in the order of magnitude Ergeria>Sediment>overlying water across all the stations during all the months. Trace metal levels were moderately elevated with Ni recording the highest percentage elevation in the clam. Health implications of consuming seafood with elevated levels of trace metals was assessed and regular assessment of contaminant levels in the Nun River is advocated to avoid severe ecologic and human health impacts. Keywords: Trace metals, bioaccumulation, Nun River, Human Healt

Cytogenotoxicity screening of untreated hospital wastewaters using the Allium cepa test

Cytogenetoxicity of University Teaching Hospital (UTH) wastewaters was investigated using the Allium cepa assay. Heterogeneous samples of untreated wastewaters from four sections of the hospital comprising the laboratories, mortuary, laundry and the kitchen were collected twice daily for six months and designated as complex mixtures. Physico-chemical parameters of the wastewaters were determined in accordance with standard methods. Onions root growth inhibition test was used to assess the toxic status of the wastewaters, while cytogenotoxicity was measured by microscopic investigation of the chromosomal aberrations. Onion bulbs were exposed to 1%, 5%, 10% 25% and 50% concentrations of the effluent samples in the dark for 72 hours before measuring the root lengths of the onion bulbs. Results of BOD, COD, TSS and pH showed levels above the maximum permissible limits for discharge of hospital effluent into the environment. There was inhibition of root growth of A. cepa in a concentration dependent pattern compared to control. An effective concentration EC50 of 8.20% and 9.1% was deduced for the 1st and 2nd samples respectively. Various morphological defects of the onions roots were also observed. Cytological analysis of root tips after 48 hrs exposure to the different concentrations showed reduction in frequency of mitosis in the meristematic zones of the root tips. Various types of structural chromosomal aberrations and micronucleus were induced in the treated cells. The University Teaching Hospital wastewaters samples are believed to contain potent toxic substances that provoked the cytogenotoxic responses herein and should be treated before discharge into the environment.Keywords: Cytogenotoxicity screening, hospital wastewaters, Allium tes

Improved optimum condition for recovery and measurement of 210Po in environmental samples

The aim of this study was to determine the optimum conditions for deposition of 210Po and evaluate the accuracy and precision of the results for its determination in environmental samples. To improve the technique for measurement of polonium-210(210Po) in environmental samples. The optimization of five factors (volume of media, acidity, removal of interference, temperature and deposition time) governing the deposition of 210Po onto silver discs were investigated. The optimum conditions for deposition of 210Po in the present study were achieved using plating solution of 80 mL hydrochloric acid (HCl) media at acidity of 0.5 M with the presence of 1.0 gram hydroxyl ammonium chloride and plating temperature of 90oC at 600 rpm for 4 hours. The recorded recoveries obtained using 209Po yield tracer in the CRM IAEA-360 and environmental samples were 85% - 98% showing that the efficiency of the new technique is a distinct improved method over existing ones. Therefore, optimization of 210Po recoveries from aqueous environmental samples can be achieved with accuracy and precision in a cost effective and time saving manner using the optimum conditions preferred in the present study.Keywords: Polonium-210, spontaneous plating, optimum conditions, environmental sample