Prolonged industrial and artisanal discharge of petroleum refinery effluents into
the Ogu Creek at the Upper Bonny estuary of the Niger Delta could pose a great
threat to the aquatic biotopes. This research investigated bioaccumulation of
selected heavy metals and petroleum hydrocarbons in the blue crab (Callinectes
sapidus) from the creek. Crabs (N=20; average length 18±20cm; weight
150.18±0.02g) were collected with nets. Mean concentrations (mg/l) of Zn
(0.044±0.01), Cd (0.002±0.00), Cr (0.001±0.00), Pb (0.001±0.00), Fe
(5.82±0.29), Mn (0.001±0.00), total petroleum hydrocarbons (TPH;
40.23±2.83) and total polynuclear aromatic hydrocarbons (ΣPAHs;7.60±1.29)
were lower in water than sediments (22.10±1.37, 1.98±0.04, 2.13±0.09,
4.80±0.57, 24.03±1.29, 0.04±0.01, 70.93±3.10 and 29.80±4.02mg/kg,
respectively) at the impacted location. Accumulations (µg/g) in digestive tract
(dtr), muscle (mus) and ovaries (ov) were as follows: Zn 10.50 (dtr), 11.00
(mus), 2.40 (ov); Cr 0.21 (dtr), 0.10 (mus), 0.04 (ov); Cd 0.01 (dtr), 0.02 (mus),
0.01 (ov); Pb 0.04 (dtr), 0.02 (mus), 0.01 (ov); Mn 0.05 (dtr), 0.03 (mus), 0.01
(ov); TPH 4.14 (dtr), 3.14 (mus), 1.20 (ov); and mononuclear aromatic
hydrocarbons (MAHs=BTEX) 0.01µg/g (dtr), 0.02 µg/g (mus), 0.01 µg/g (ov).
Accumulations of TPH and BTEX were significantly (p<0.05) higher at the
impacted location (p = 0.03 and 0.02, respectively) than reference locations.
High TQ/HQ values of 1.59, 2.82 and 1.90 were recorded for Zn, TPHs and
PAHs, respectively. The results raise environmental health concerns among
consumers of the aquatic food in the area.