Concentration Distribution and Ecological Risk Assessment of Polycyclic Aromatic Hydrocarbon in Kolo Creek Niger-Delta Nigeria

The ecological risk assessment of 16 USEPA priority polycyclic aromatic hydrocarbon (PAHs) in water and sediments of Kolo creek, Niger Delta Nigeria was assessed the samples were collected from November, 2018 to June, 2019 from seven locations (A-G) along the creek. The samples were extracted using standard methods and analyzed using gas chromatography (model: HP5890 S). The concentrations of the PAHs in the water and sediment samples ranged between 0.000 - 9.239 µ/L and .002 – 374.35µg/Kg respectively. All the compounds analyzed were detected in all the sampling places, even area far from the flow stations. Hence, the urban runoffs, sewage discharges, and agricultural activities are implicated. Four rings hydrocarbon were present in higher concentration when compared to other PAHs in all sampling sites, with benz (a)anthracene having the highest values in both matrixes. Similarly, lower molecular weight (LMW) PAHs were present in lower concentrations in all sampling sites and they are known to exhibit higher lethal toxicity than the larger PAHs. HMW were present in high concentrations than LMW and are persistent in the environment as a result of their increase resistance to oxidation, reduction and vaporization as molecular weight increases. Similarly, The PAFs of the investigated creek is less than 5%, suggesting existences of minor ecological risks that are insignificance. However, the TEQs detected in high molecular weight showed that there is possibility of cancer to those who may be exposed to the bottom sediment. The indices measured in this habitat may put more pressures to the aquatic organisms and cause drastic changes to their ecosystem which may lead to species extinction.