Hazardous metals levels in groundwater from Gokana,Rivers State,Nigeria: Non-cancer and cancer health risk assessment

This study investigated heavy metals concentration in groundwater in six coastal communities in Gokana, Rivers State, namely, Gbe, K-Dere, B-Dere, Mogho, Kpor and Bodo City and the human health risk posed to the local populace via ingestion and dermal contact using non-carcinogenic and carcinogenic health risk assessment. The mean values of the heavy metals ranged between 0.02–0.86, 0.16–0.19, 0.03–0.10, 0.02–0.03 and 0.01–0.17 for Mn, Ni, Pb, Cd and Cr, respectively. The heavy metals were above the drinking water quality recommended limits in all the study sites. Estimations of average daily dose (ADD) and dermal absorbed dose (DAD) health risk indicates that Mn, Ni and Pb posed human health risk via ingestion contact pathway. However, hazard index (HI) values of Cd and Cr for ingestion pathway were >1.0 and the estimated Lifetime of Carcinogenic Risks (LTCR) for Ni, Cd and Cr exceeded the predicted lifetime risk for carcinogens of 10^?6 from ingestion pathway. Furthermore, there were more appreciable risk from Ni and Cr in the study sites as LTCR value in most sites were >10^?4_. This study indicates possible non-carcinogenic and carcinogenic human health hazard from groundwater consumption in Gokana via oral ingestion.     

Trace Metal Contents of Selected Seeds and Vegetables from Oil Producing Areas of Nigeria

The concentrations of accumulated trace metals in selected seeds and vegetables collected in the oil producing Rivers State of Nigeria were investigated. The values were compared with those of seeds and vegetables cultivated in Owerri, a less industrialized area in Nigeria. The lead (Pb) and cadmium (Cd) contents of the seeds obtained from Rivers State ranged between 0.10 and 0.23 μg/g dry weight, while those of the seeds cultivated in Owerri fell below the detection limit of 0.01 μg/g dry weight. The highest manganese (Mn) level (902 μg/g dry weight) was found in Irvingia garbonesis seeds cultivated in Rivers State. Similarly, the highest nickel (Ni) value (199 μg/g dry weight) was also obtained in I. garbonesis, however, in the seeds sampled in Owerri. The highest copper (Cu), zinc (Zn), and iron (Fe) levels (16.8, 5.27, and 26.2 μg/g dry weight, resp.) were detected in seeds collected in Rivers State. With the exception of Talinum triangulae, Ocinum gratissimum, and Piper guineese, with Pb levels of 0.09, 0.10, and 0.11 μg/g dry weight, respectively, the Pb and Cd levels in the vegetables grown in Owerri fell below the detection limit of 0.01 μg/g dry weight. The trace metal with the highest levels in all the vegetables studied was Mn, followed by Fe. The highest concentrations of Ni and Cu occurred in vegetables collected from Rivers State, while the highest level of Zn was observed in Piper guineese collected in Owerri, with a value of 21.4 μg/g dry weight. Although the trace metal concentrations of the seeds and vegetables collected in Rivers State tended to be higher than those of the seeds and vegetables grown in Owerri, the average levels of trace metals obtained in this study fell far below the WHO specifications for metals in foods.     

Trace-metal contamination of the African giant land snail Archachatina marginata from Southern Nigeria

The levels of bio-accumulated trace metals in the African giant land snail Archachatina marginata, collected in six different states of Southern Nigeria, were determined. The Cu and Fe levels were 3.0-9.8 and 12.4-35.2 mg/kg body weight, respectively (Table). Similarly, the concentrations of Zn, Ni, Pb, and Cd were 10.3-20.5, 3.20-10.4, 0.80-6.00, and 0.60-0.84 mg/kg, respectively. Although the trace-metal levels for some samples collected in highly industrialized zones approached or even considerably exceeded the upper WHO limits, the average concentrations of trace metals recorded in this study remained below critical values.     

Assessment of heavy-metal profile of the New Calabar River and its impact on juvenile Clarias gariepinus

We have determined the heavy-metal status of the lower reaches of the New Calabar River in the Niger Delta region over a 40-km-long distance, and its impact on the development of catfish (juvenile Clarias gariepinus). The total mean concentrations of dissolved trace metals in the river were 0.01, 0.85, 0.56, 2.08, 0.05, 12.0, and 6.59 mg/l for Hg, Pb, Cd, Cu, Cr, Fe, and Zn, respectively. The accumulated concentration of trace metals in the muscles of different mature fish caught from the river were examined, and the results fell within the action levels adopted in most countries. To evaluate the contributions of trace metals to fisheries depletion, eggs of C. gariepinus were hatched in dilution water spiked with the total mean metal levels determined in the river water. Our results indicate substantive inhibition of egg hatch even at very low concentrations of the majority of the trace metals studied, with mortality rates well above 50% after 216 h of exposure (Table 5). These findings suggest that trace metals (except for Zn), even at very low concentrations, negatively affect fish hatch and fry rearing, implying that aquatic milieus contaminated by trace metals are not suitable as nursery grounds for fish cultures.     

Comparison of Chicken Manure and Urea Fertilizers as Potential Soil Amendments for Enhanced Phytoextraction of Heavy Metals

Cadmium (Cd) solubilization in soil and uptake by Mucuna pruriens var. pruriens and Sphenostylis stenocarpa was studied in response to the chicken manure and urea fertilizers application types. In this study, 0.8 g each of the amendments was applied to petroleum-contaminated soil in a pot experiment. Results indicate that the chicken manure application at 14 days before planting gave significantly higher shoot dry matter than its urea counterpart under conditions of Cd stress. Chicken manure application resulted in less Cd solubilization as compared with urea fertilizer dosing. The chicken manure application also significantly increased the shoot Cd accumulation despite its lesser effect on Cd solubilization; thus, it is expected to minimize the risk of groundwater contamination. Chicken manure amended treatment showed greater Cd tolerance for the two species investigated and S. stenocarpa did not support Cd phytoextraction. Although the amendments gave marked reduction in Cd phtotoxicity, those of the urea fertilizer gave only rapid, but short, growth support.     

Ethanol via Regulation of NF-κB/p53 Signaling Pathway Increases Manganese-Induced Inflammation and Apoptosis in Hypothalamus of Rats

Biological Trace Element Research - The diet is a major route of manganese (Mn) exposure for humans. Interestingly, several epidemiological data demonstrated an increase in the incidence of alcohol...     

Nutrient Profile of a Contaminated Soil Phytoremediated by Centrosema pubescen and Mucuna pruriens

Soil nutrients contribute to ecosystem-level processes and are important for productivity, community structure, and fertility in terrestrial ecosystems. Crude oil–stressed agricultural soil was subjected to phytoremediation for 12 weeks, and the nutrient status thereafter was characterized to investigate the inherent effects on such soils in relation to nutrient mineralization and community shifts. Manure additions significantly increased Mg, Na, NO₃-N, PO₄ ^?, and SO₄ ^2? contents along with pH values. Accumulated biomass and leaf area measurements were used to monitor nutrient cycles upon amendment addition. Experimental results indicate that after 90 days, the biotreatment had significantly higher levels of monitored nutrients (above 2500 mg/kg NO₃-N) than the unplanted control (<500 mg/kg NO₃-N), and compared well with the uncontaminated control. The results from this study highlighted inherent advantages of phytoremediation as a soil cleanup technique in terms of soil quality recovery and preservation.