International Journal of Marine Science 2015, Vol.5, No.58: 1-6
4
Figure 1 Map of the Qua Iboe Estuary
Figure 2 Seasonal variation of metals in water
Figure 3 Seasonal variation of heavy metals in sediments
effluents replete with iron scales from corroded iron
pipes, containers and scraps into the water body
including the Stubbs creek which empties into the
estuary close to sampling location 2 of this study.
However, these values are lower than values obtained
in other studies in the region and Canada sediment
quality criteria (Udosen and Benson, 2006; CEQC,
1991).
Mean zinc concentration range of 0.12 to 0.20mg/L in
water, were below the maximum contamination level
of 15 and 3.0 mg/l recommended by WHO (2011),
and NIS (2007) respectively. Zn is present in large
amount in natural water and next to Fe in terms of
concentrations in this study. These values were lower
than mean concentration of 10mg/kg obtained from
Bodo creek in the Niger Delta (Vincent-Akpu et al.,
2015). The relatively low Zn level suggests that the
domestic and industrial effluents reaching the estuary
conceivably contained low concentration of the metal.
Drinking-water containing <3 mg/l zinc may not be
acceptable to consumers (WHO, 2011).
The mean Pb concentration (0.01- 0.02mg/l) recorded
in Qua Iboe water is slightly higher than 0.01 mg/l
recommended by WHO (2011), and NIS (2007). Study
by Lawson, (2011) showed that the concentrations of Pb
were very low and could not be detected in water from
the swamps of Lagos lagoon, and attributed it to the
absence of dry cell batteries manufacturing industries
from catchment areas of the lagoon. This finding is
contrary to those documented for Qua Iboe river
estuary (Ebong et al., 2004); Stubbs creek (Udosen
and Benson, 2006); Niger Delta mangrove creek
(Oribhabor and Ogbeibu, 2009), and Ikpoba reservoir
(Wangboje and Ekundayo, 2013), who report that Pb
concentrations in their study exceeded the WHO
maximum permissible level for drinking water.
Pb concentrations ranged from 0.006 – 0.171 mg/kg in
the sediment. According to the Nigerian Industrial
Standard (NIS), the adverse health impacts of Pb
include interference with vitamin D metabolism,
indenting the mental development of infants,
carcinogenic activity and toxicity to the central and
peripheral nervous systems. Low levels of Pb
recorded in this study are consistent with previous
studies in Niger Delta (Vincent-Akpu and Yanadi
2014; Adeleye et al., 2011).
The mean Cd concentration (0.003 mg/l) in water was
recorded for station 2 while 0.01 was recorded for
stations 1and 3. The work of Fakayode, (2005),
documented lower mean Cd concentration of 0.004
mg/l for the Alaro River and Cd value of 0.036±0.036
mg/l recorded for Qua Iboe river estuary (Ebong et
al., 2004), while mean Cd range of 1.50mg/l to
2.60mg/l was recorded for the Delimi River, Jos,
Nigeria (Njoku and Keke, 2003).
Sources of Cd include batteries, fossil fuels, fertilizers,
plastics, alloys and paints. Cadmium accumulates
primarily in the kidneys and has a long biological
half-life in humans of 10–35 years (WHO 2011).
The observed seasonal differences in trace metals in
sediments and water depict the influence of runoffs
which contribute to the dilution of these metals during
