The concentrations of six trace metals (Pb, Zn, Cu, Cr, Ni and Cd) in fish and sediment samples from Kubanni River located in Zaria, Northern Nigeria, were investigated. The river receives agricultural runoff and municipal wastewaters, and is utilized for drinking, fishing and irrigation. Fractionation of trace metals in the river sediments, the risk to water column contamination and the levels of the six trace metals in Clarias gariepinus and Oreachromis niloticus samples were established. There was considerable risk to river water contamination based on the calculated individual trace metal average contamination factors (IACF) obtained for the river sediments from the trace metal sequential extractions. Also, the distribution and concentration of trace metals obtained in liver, gill, muscle and bone of C. gariepinus and O. niloticus showed that the human health risk for trace metals in muscles of fish were low, but individuals consuming fish livers might be at risk from ingestion of toxic metals at unacceptable concentrations.

The toxic effects of anionic dyes such as tartrazine and sunset yellow on humans and the aquatic environment are of serious concern. The need for the removal of these dyes from wastewaters led to the use of adsorption techniques as a cheap and efficient treatment method. Thus, this research was based on the preparation of a low-cost activated carbon derived from cassava sievate designated as CS, which was utilized in the adsorption of sunset yellow and tartrazine from simulated wastewater. The sorption process was carried out under varying process factors in a batch mode. Adsorbent characterization displayed the presence of surface functional groups by the FT-IR and a porous structure as revealed by scanning electron microscopy. Optimum dye uptake was recorded at pH (1.0–2.0), temperature (30–40 °C), CS dosage (0.1 g), and dye concentration (150 mg/L). A maximum CS monolayer uptake of 20.83 and 0.091 mg/g was recorded for tartrazine and sunset yellow dyes, respectively. The pseudo-second-order (R2 > 0.99) and Freundlich (R2 > 0.92) models were most fitted to the kinetics and isotherm data of the uptake of the dyes on CS. The adsorption equilibrium attainment was reached was within 90 min of dye sequestration. The experimental results revealed that both sunset yellow and tartrazine dyes were considerably adsorbed onto the environmentally compatible and low-cost activated carbon derived from cassava sievate.

No abstract

No abstract

ABSTRACT:The effects of smoking on proximate composition, energy values and concentrations of polycyclic aromatic hydrocarbons (PAHs) were studied in raw and smoked samples of catfish (Clarias gariepinus) and tilapia (Oreochromis niloticus). Crude protein was higher in the tilapia sample for both raw and smoked samples. There was significant difference (P<0.05) in the lipid contents of raw and smoked samples of both species. Mean naphthalene concentration was significantly higher (P<0.05) than those of other PAHs analyzed in raw and smoked samples of both species. Mean benzo (a) pyrene (BaP) concentrations and total mean PAH concentrations (∑mPAH) exceeded the EU limits in raw muscle samples. All the PAHs analyzed were detected in the smoked samples. Mean BaP concentrations and total mean PAH exceeded the EU maximum limits (2.0 and 10 µg/kg) in the muscle of smoked fish and fishery products. Total mean concentration of the four indicators of PAH contamination gave the values of 0.018 and 0.050; 0.014 and 0.012 mg/kg for raw and smoked samples of catfish and tilapia respectively. It could be inferred that the smoking process generally increased the mean total PAH levels in the fish samples and there is urgent need for relevant authorities to take appropriate action due to the public health implications of PAH contamination.