Volume 9 October 2004
ISSN 1438-7890 |
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African
Journal of Environmental Assessment and Management
Revue africaine de gestion et d’évaluation environnementales |
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The
Ebocha-8 Oil Spillage: II.
Fate of Associated Heavy Metals Six Months After
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Leo C. Osuji and Chukunedum M. Onojake
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| Some implications of the Ebocha-8 oil pollution
on Ni, V, Pb, Cu and Cd as well as its concomitant effects on
soils were evaluated
approximately six months after recorded incidence of oil spillage.
Mean concentration of nickel in surface and subsurface soils of the
polluted plots (± Standard Error at 95% Confidence Limit) was 12.80±3.20mg/kg
in polluted soils and 6.90mg/kg in unpolluted soils. Copper was 5.20±0.68mg/kg
in polluted soils and 1.90mg/kg in the control soils; lead varied
from 10.0mg/kg to 10.8mg/kg in polluted plots but was 3.6mg/kg in
the control site. Concentrations of vanadium and cadmium were
<0.20mg/kg and showed no significant differences in polluted and
control soils. While oiling might have been partly responsible for
the significantly higher levels of nickel, copper and lead of the
Ebocha polluted soils, the slightly lower soil-pH (i.e, slightly
higher acidity), higher moisture content, mobility of metals, TOC
and TOM detected in the affected soils as well as the intense
rainfall and flooding that preceded the period of sampling may have
also contributed in part to the enhanced concentrations of the
metals. Immediate depollution
measures should be effected on the affected site to avoid the
possibility of biomagnification
of these metals, especially Ni and V
which are inherently persistent. On the other hand, liming of
the soils with calcium and magnesium compounds may de-acidify the
acidified soils by appropriately raising their pH to an acceptable
range
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