Residual levels of lead, chromium, cadmium and zinc in water and fish tissue from
Ubeji River, Warri and blood samples from residents of Ubeji were analysed. Control water and fish
samples were obtained from Eleyele River and blood from residents of Ibadan. All the samples
collected were digested using a modified procedure from the Association of Official Analytical
Chemists (AOAC) and were subsequently analyzed using Atomic Absorption Spectroscopy. Levels of
lead and cadmium in Ubeji river were significantly higher than levels in Eleyele River. Fifty fish
samples from five species (
Citharinus citharus
,
Liza falcipinis
,
Brycinus macrolepidotus
,
Polydactylus
quadrifilis
and
Tilapia zilli
) were analysed. Lead concentration (ppm) was highest in
C. citharus
(76.07±161.48) and least in
T. zilli (23.16±26.30). Chromium was not detected in
B. macrolepidotus,
P. quadrifilis and
T. zilli. Concentrations of all heavy metals detected, except zinc, in the fish species
were higher than WHO permissible limit. Lead, Cadmium and Zinc concentrations in the tissues of the
control fish were significantly lower (p>0.05) than those recorded in fish from Ubeji River. There were
no statistically significant differences in heavy metal concentration in fish gills and muscle (p>0.05).
Lead and cadmium levels in Ubeji river significantly exceeded (p=0.0 and p=0.012) the permissible
limits for aquaculture and drinking. Levels of Chromium (1737.17±2996.01), Zinc and Lead
(149.35±188.28 and 123.49±350.85 respectively) were significantly high (p<0.05) in the 101 human
blood samples screened, while concentrations of Cadmium was comparatively low (10.11±10.71).
Lower levels of cadmium, zinc and lead (8.54± 7.49, 79.89±62.65 and 53.46±57.17, respectively) were
recorded for the control samples from Ibadan. This study highlights the high levels of heavy metals in
the Ubeji River and suggests the need for interventions to stem the tide of pollution in the river. It
would also be important to assess health problems that may arise as a result of contact and continuous
use of the water. @ JASEM