ABSTRACT
This study evaluates the physico-chemical parameters and heavy metals in water, sediments and Tympanotonus fuscatus obtained from three sample sites along Iko River in Eastern Obolo LGA, AkwaIbom State. The heavy metal analysis results on Pb, Cd and Ni in sediments and Tympanotonus fuscatus were used to estimate the human health and ecological risk assessment of the study area. The human health risk assessment tools utilized in this study were estimated dietary intake (EDI), total hazard quotient (THQ) and hazard index (HI) while sediment pollution parameters evaluated were contamination factor (CF), contamination degree (CD), pollution load index (PLI) and geoaccumulation index (Igeo). Results obtained showed that EDI of Cd in periwinkle in the study sites ranged from 0.2 – 6.4 µg/kg-bw/day and exceeded the provisional tolerable dietary intake (PTDI), while EDI for Pb (0.0004 – 2.6 µg/kg-bw/day) and Ni (0.32 – 2 µg/kg-bw/day) was within the limit for all sites, except Ni in site II (34 µg/kg-bw/day) which was higher than the PTDI of 5 µg/kg-bw/day. The THQ of Cd in all sites was greater than 1, while Pb and Ni generally recorded THQ < 1. The hazard index (HI) was as follows: site I (2.36), sites II (24.44) and site III (6.5), highlighting a potential hazardous effect to humans as a result of the consumption of Tympanotonus fuscatus obtained from site II and III. The sediment pollution assessment revealed that the contamination factor (CF) and geoaccumulation index, Igeo of Cd were far above the permissible limits while Pb and Ni were mostly within limits. The estimated contamination degree (CD) and pollution load index (PLI) showed a high degree of pollution, which can be mainly attributed to the high degree of Cd contamination in the sediment. Therefore, the area under investigation is highly polluted and the periwinkle obtained from Iko river in the study area is unfit for human consumption.
ABSTRACT
This study was done to examine the comparative effect of different concentrations of kerosene and diesel on the ion regulatory characteristics in Tympanotonus fuscatus after exposure. Tympanotonus fuscatus were exposed to different concentrations of kerosene and diesel (10.40, 15.60, 21.00 and 26.00 ml/L) and a control to examine their effect on sodium, potassium and chloride ions in the muscle and viscera for six days. In the muscle, kerosene generally increased the levels of sodium, potassium and chloride ions in the lower concentrations (10.40 and 15.60 ml/ L) above the control values. In the higher concentrations (21.00 and 26.00 ml/L), these parameters were observed to be lower than the control value. Whereas the levels of sodium, potassium and chloride ions in the viscera increased above the control value in all the exposure concentrations except potassium 15.60 ml/L and chloride at 21.00 and 26.00 ml/L concentrations. In the viscera, sodium ion levels were lower than the control value in both kerosene and diesel media except at 21.00 ml/L concentration. Potassium ion levels in kerosene increased above the control values except at 26.00 ml/L, while lower levels of potassium ions were recorded in all the exposure concentrations. Chloride ions were lower than the control value in all the exposure concentrations of kerosene and diesel. The results of this study showed that both kerosene and diesel altered the ion regulatory and osmolality of Tympanotonus fuscatus and kerosene being more effective. The toxicants seem to be parameter and tissue specific in their mode of action.