Abstract

A field bioaccumulation study was carried out. Juvenile hemichromis fasciatus in net cages were exposed to contaminated surface water in borrow pits located within oil exploration and production (E & P) installations within the Niger Delta region of Nigeria during wet and dry seasons.

Percentage mortality ranged between 2% and 3.8%. Assuming a first order kinetics and steady state at day 14; toxicokinetic variables were obtained for xenobiotics assessed. The up-take rate constant k, ranged from 38.47 ×10^-2 d^-1 (pit B, wet season) to 40.82 ×10^-2 d^-1 (pit A, dry season) for TPH, while PAHs ranged between 22.40 ×10^-2 d^-1 (pit B, wet season) and 24.98 ×10^-2 d^-1 (pit A, dry season) for both pits and seasons.

Amongst the water borne metals k for hemichromis fasciatus ranged from 4.66×10^-2 d^-1 to 47.66 ×10^-2 d^-1 and 2.70 ×10^-2 d^-1 to 33.90×10^-2 d^-1 in pits A and B respectively during both seasons. The order of uptake was Fe <Pb< Cr < Ba < Cd < Zn < Cu < Ni, while As (arsenic) recorded a zero uptake.

Calculated BCF in both pits and seasons ranged from 2.832 LKg^-1 to 4.844 LKg^-1 for TPH and 2.636 LKg^-1 to 8.0 LKg^-1 for PAH, while for metals - Ba, Cd, Cr, Cu, Fe , Ni, Pb and Zn, values ranged between 0.211 LKg^-1 to 71.727 LKg^-1. Hemichromis fasciatus exhibited greater uptake of analytes in the dry season and the amount of heavy metals accumulated were all below the provisional maximum tolerable daily intake (PMTDI).

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