E. F. Ajagbe; J. K. Saliu; S. O. Ayoola; N. D. Menkiti
Abstract
Polychlorinated biphenyls (PCBs) are a health risk for high trophic level predators and the Stockholm Convention requires measures to reduce or eliminate their release into the environment. The study was conducted an ecological survey on River Ogun, Lagos, Nigeria, quarterly over a period of two years ...
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Polychlorinated biphenyls (PCBs) are a health risk for high trophic level predators and the Stockholm Convention requires measures to reduce or eliminate their release into the environment. The study was conducted an ecological survey on River Ogun, Lagos, Nigeria, quarterly over a period of two years (March 2013-February 2015). Water physicochemistry and the levels of nine PCB congeners were analyzed in water and sediment samples from five river zones: Agboyi, Maidan, Owode Elede, Kara, and Akute. Water physicochemistry showed significant (p<0.05) increases in conductivity, turbidity, temperature, salinity, total dissolved solids, and dissolved oxygen in the dry season compared to rainy season across the zones, while there was an increase in pH, transparency and depth in the rainy season across the zones. Mean temperature in the range of 28.53 -28.95°C, the mean pHranged between 5.58-7.74, mean total dissolved solid ranged between 0.67 -1.69 g/L, mean conductivity ranged between 0.77 mS/cm -0.94 mS/cm, mean salinity ranged between 0.05 -0.42%, mean turbidity ranged between 29.30-30.50NTU, mean Secchi-disc transparency ranged between 2.88-3.16m, mean depth ranged between 3.21-3.65m while meaning dissolved oxygen ranged between 14.54- 22.65mg/L.PCB congeners were analyzed in sediment and water samples. The analyzed categories were the IUPAC numbers: non-ortho PCBs (CBs 8, 18 and 58), mono-ortho PCBs (CBs 87, 128,170 and 195) and dl-PCBs(CBs 206 and 209). The mean concentrations of PCBs in the sediment samples for all zones ranged from 0.000078-0.01μg/kg, while the mean concentrations of PCBs in the water samples for all the sampled zones ranged from 0.00006-0.006mg/L. The total PCBs concentrations in all water samples in this study for the rainy and dry seasons were 0.0296 mg/Land 0.0299 mgL-1, respectively. The hazard quotient (HQ) values for the rainy season ranged from 0.0039 - 0.014 and between 0.0047 - 0.013571 for the dry season. The cancer risk for the rainy season ranged from 3.90 × 10-6 - 9.82 ×10-6, while that of the dry season ranged from 1.57× 10-7 - 3.17 × 10-7. There was no significant difference between the congeners when the samples were subjected to descriptive (mean and standard error) and analysis of variance statistics and P<0.05 was considered to indicate statistical significance. Means were separated using Bonferroni’s multiple comparison tests, p<0.05). PCB concentrations in all the zones were above US EPA limits in surface waters (0.0005 mg/L), which is a cause for environmental concern for River Ogun.
S. O. Ayoola; G. T. Olorunsanmi; A. O. Oke
Abstract
Industrial waste discharge has increased the hazard of water pollution. The total hydrocarbon content and bioaccumulation of heavy metals in Sarotherodon melanotheron at Atlas cove area and at Okobaba end of Lagoon Lagos were assessed between November, 2014 and January, 2015. The physicochemical parameters ...
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Industrial waste discharge has increased the hazard of water pollution. The total hydrocarbon content and bioaccumulation of heavy metals in Sarotherodon melanotheron at Atlas cove area and at Okobaba end of Lagoon Lagos were assessed between November, 2014 and January, 2015. The physicochemical parameters were determined according to APHA-AWWA-WEF and heavy metals in the fish species were determined using Atomic Absorption Spectrometer. The total hydrocarbon content (THC) in the fish samples were analysed by using Soxhlet extraction gravimetric methods. The heavy metal values evaluated are Fe, Cr, Pb, Ni and Cu. The concentration of Iron (Fe) in Sarotherodon melanotheron was 72.72 ± 125.95mg/kg, Chromium (Cr)- 10.29 ± 4.61mg/kg; Lead (Pb)- 1.08 ± 0.23mg/kg; Nickel (Ni)- 0.39 ± 0.26mg/kg; and Copper (Cu)- 0.20 ± 0.26mg/kg at Atlas cove area while at Okobaba the concentration were;Fe-115.98±87,Cr-5.25±1.02,Pb-2.04±1.50,Ni-0.78±0.08,and Cu is 0.36±0.15mg/kg. The levels of accumulation of all the heavy metals in Sarotherodon melanotheron were above the WHO permissible limits. The concentration of n- alkanes in Sarotherodon melanotheron at Atlas cove was 164.69 ± 97.04µg/g, polycyclic aromatic hydrocarbon (PAH) was 73.58 ± 72.48µg/g, and total petroleum hydrocarbon was 526.67 ± 214.34µg/g. The average intake of polycyclic aromatic hydrocarbon through fish consumption at Atlas cove area was estimated to be 5039.94 ± 49.2mg/kg; body weight/day. The mean concentration of n-alkanes hydrocarbon in Sarotherodon melanotheron at Okobaba was 152.62±54.11µg/g, the PolycyclicAromatic Hydrocarbon (PAH) was 74.4±50.30 µg/g.The carcinogenic high molecular weight polycyclic aromatic hydrocarbons (HMW-PAH) were of higher concentrations than the lower molecular weight polycyclic aromatic hydrocarbon (LMW-PAH). Therefore, Atlas cove area is more exposed to carcinogenic health risks associated with the consumption of the studied fish than Okobaba end of Lagos Lagoon. This indicates significant carcinogenic health risks associated with the consumption of black jaw Tilapia fish caught from the study areas.
