The ecological effects of oil spill in the environment were studied in Warri riverine areas of Ubeji and Jeddo, Delta State, where an oil spill occurred and cleanup or remediation was not carried out for over a year prior to this evaluation. The American Public Health Association (APHA) and the American Society for Testing and Materials (ASTM) methods were employed for the laboratory test for organics [polyaromatic hydrocarbon; total petroleum hydrocarbon (TPH)] and heavy metals in the water and sediment. The results indicated that there were still significant concentrations (P <0.05) of organics indicating hydrocarbon pollution. Mean concentrations recorded for TPH in Ubeji and Jeddo waters were 23.60 ± 1.18 mg/L and 29.96 ± 0.14 mg/L respectively while total PAHs was 0.009 ± 0.002 mg/L and 0.008 ± 0.001 mg/L. Mean concentrations of TPH in the sediment was 48.83 ± 1.49 ppm and 1093 ± 74 ppm respectively while total PAHs was 0.012 ± 0.002 ppm and 0.026 ± 0.004 ppm. Low concentrations were recorded for most of the heavy metals in the water and sediment. Hydrocarbon degrading bacteria (HDB) recorded mean values of 3.86E + 03 and 3.44E + 02 for Ubeji and Jeddo waters, while Hydrocarbon degrading fungi (HDF) recorded mean values of 2.86E + 03 and 2.46E + 02 respectively. The observed concentrations of hydrocarbons in the study areas should provide the impetus for regulatory surveillance of oil discharged intentionally/unintentionally into the Warri riverine waters and sediment since hydrocarbon released into the environment sorb to the sediment particles where they cause harm to organisms in the sediment and overlying waters.

The ecological effects of oil spill on environmental media and organisms (pelagic, bottom dwelling organism) in the riverine areas of Odidi and Egwa in the Niger Delta ecological zone of Delta State was investigated approximately six months after the spill. The content of petroleum hydrocarbons and heavy metals (lead, copper, zinc, iron and chromium) in the water, sediment, fish (Clarias gariepinus) and snail (Pachymelania byronensis) was evaluated to determine the effect oil spill had on the environmental matrix and the organisms. The mean concentration of total petroleum hydrocarbon (TPH) in the sample matrix (water, sediment) and organisms (fish and snail) from Odidi and Egwa Rivers was above the Department of Petroleum Resources (DPR) limits of 50 mg/L and 5000 mg/kg. The control level of TPH in the media and organisms was less than 5 mg/kg. The mean water concentrations of iron and chromium were above their respective DPR limits of 1.00 and 0.03 mg/L. The concentrations recorded for iron in Odidi and Egwa waters was 2.96 ± 0.01 mg/L and 2.95 ± 0.08 mg/L while chromium was 0.33 ± 0.01 mg/L and 0.34 ± 0.01 mg/L respectively. Similarly, the mean concentrations of heavy metals in the water, sediment, cat fish (Clarias gariepinus) and snail (Pahymelania byronensis) were all significantly different from the control station (P<0.05). In other to prevent the adverse effects on environmental components and organisms resulting from oil spill, immediate clean-up of the environment and remediation measures should be carried out to prevent the bioaccumulative effects that could result from long term exposure to crude oil spill / pollution. This is with the view of safe guarding environmental media, aquatic fauna and subsequently man, who constantly feed on these organisms.

This study examined the phyto-toxic effects of a commonly named non-selective herbicide glyphosate (Roundup™) on onions (Allium cepa Linn.). The study was necessitated due to the indiscriminate use and release of Roundup™ for weed control in the Niger Delta soils of Nigeria. The Organisation for Economic Co-operation and Development (OECD) standard protocol # 208 was adopted. The short-term phyto-toxic consequence on onion (A. cepa L.) was determined after a 4-day exposure to varying concentrations of the test chemical at 0.625, 1.25, 2.5, 5 and 10 mg/L, respectively. The percentage growth rate decreased as percentage growth rate inhibition efficiency increased, which implies that the effect of the herbicide was concentration dependent. The mean percentage growth rate inhibition efficiency relative to the control was 28, 47, 61, 73 and 96%, respectively. The effective concentration (EC 50 ) for % Inhibition efficiency was 1.550 mg/L with a 95% confidence interval of 1.269 to 1.848 mg/L. The biological alterations on the onions in the test solutions varied in order of increasing concentrations. Some observations made include decolouration of the test solutions and stunted growth especially at the highest concentration of 10 mg/L. Other effects include: bulb deformation, tissue and root damage. There was significant difference between the exposed species and the control at P < 0.05. The use of the herbicide Roundup™ with such hazardous effects can harm plants especially onion which is a very viable food product of man. This could lead to likely distortion on the ecosystem balance of onions (A. cepa) and similar plants and subsequent effect on human, the major end user.

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