|
Microbiological impacts of
produce water discharges in nearshore shallow marine waters
near Chevron’s Escravos tank farm, Nigeria
Chuma C. Okoro
Department
of Biological Sciences and Biotechnology, Caleb University,
Lagos, Nigeria. E-mail:
chuma2k2001@yahoo.com.
Tel: 08033072754, 01-7430285.
Accepted
14 January, 2010 |
|
Microbiological and Physicochemical survey was undertaken in
produced water and its receiving environment with the aim of
verifying the likely impacts of produced water constituents
on the immediate receiving marine near shore shallow
environment. The sampling was carried out in two seasons,
late wet season and late dry season. The results obtained
indicate that the chemical constituents of the discharged
produce water are capable of sustaining microbial growth and
proliferation. Produce water from Escravos tank farm had
relatively moderate concentrations of hydrocarbon utilizing
microorganisms and sulphate reducing bacteria and the
concentration of these organisms were much higher at the
point of discharge of the produced water. Physicochemical
analysis showed that Produce water had lower salinity and
sulphate levels than the receiving marine water but the
reverse was the case with the BOD, COD and Hydrocarbon
constituents. The two seasons under investigation showed
similar results. From the analytical data, it can be
advanced that the impacts of produced water microbial flora
on the receiving environment is limited to the vicinity of
the discharge point of about 100 m in diameter and also to
some extent up to a distance of 500 m upstream along the
direction of flow of produced water discharges. It is
expected that while the hydrocarbon degrading microorganisms
plays a beneficial role of degrading and detoxifying
abundant produced water hydrocarbons in the sediment and the
surface water, Sulphate reducing bacteria might at the same
time be playing a detrimental role of oxidizing certain
organic compounds or hydrogen and reducing sulphate and
other reduced sulphur compounds in the marine water and
sediment to hydrogen sulphide which can be very toxic to
bacteria, aquatic animals and man.
Key
words:
Produced water, sulphate reducing bacteria, hydrocarbon
utilizing bacteria. |
