EVALUATION OF TOTAL HYDROCARBON LEVELS IN SOME AQUATIC MEDIA IN AN OIL POLLUTED MANGROVE WETLAND IN THE NIGER DELTA

Abstract

The total hydrocarbon (THC) levels in the surface waters, sediments and biota in an oil polluted mangrove wetland located in the Niger Delta Nigeria, were studied between November 2001 and October 2002. Result showed elevated THC mean levels in water (23.6 + 4.3mg/l), sediment (386.44 ± 50.28 μg/g), Tympanotonus fuscatus (Periwinkle) (449.30 ± 55.42 μg/g) and Periophthalmus papillio (Mudskipper) (278.57 ± 34.57 μg/g), indicating a polluted environment. THC levels in water at the wellhead stations were above 10mg/l being the maximum recommended limit by the Federal Ministry of Environment (FMENV) Nigeria. There was a pronounced seasonal variability with the highest being in the dry season (P < 0.05) due to the higher level of increased oil activity in that season. THC levels in water correlated significantly (r = 0.927) with THC levels in the sediment (P < 0.01). The implication is that as the THC remains within the surface water column in relation to the sediment the more the organisms in the environment are impacted. This is shown by the significant correlations (P<0.01) of THC between the organisms and their surrounding media. The high levels of THC in the surface water and sediments of these stations suggest that aquatic life water quality may adversely influence biological functions of exposed species, while the level in the Tympanotonus fuscatus and the Periophthalmus papillio calls for concern as it can have some health-risk implications in man who is the final consumer.