Effects of PAHs on the early life stages of aquaculture fishes

Abstract

This study evaluated the ecological risk assessment of heavy metals in cassava mill effluents contaminated soil in rural community in the Niger Delta region of Nigeria. Secondary data was used for the ecological risk assessment. Two background scenarios i.e. geometric mean (BGM) and median mean (BMM) was used as the reference value. The heavy metals that were assessed for ecological risk include viz: Cr, Zn, Cu, Co, Ni, Mn, Pb and Cd. 50% of mean detected individual heavy metals were considered for the location that was not detected. Assessment of the ecological risk was carried out following well established protocol. The results of the potential ecological risk (ER), Ecological risk index (ERI) and Monomial potential ecological risk (MPER) of heavy metals showed low risk under both scenarios except for Cd in one of the locations that showed moderate risk for MPER under both background scenarios in wet season. The distribution of the heavy metals based on potential ecological risk were in the order; Cd > Ni > = Pb > Co > Cu> Cr > Mn = Zn (BMM) and Cd > Pb > Ni = Co > Cu = Cr > Mn > Zn (BGM) for wet season and Cd > Pb = Ni = Cu > Co > Cr > Mn = Zn (BMM) and Cd > Pb > Cu = Co > Ni > Cr > Mn = Zn for dry season. The study showed low ecological risk associated with cassava mill discharged into the environment. cassava mill effluents on soil