A BASELINE ENVIRONMENTAL AUDIT USING A PROPOSED MODULAR REFINERY SITE IN BAYELSA USING THE TESTIS OF SAROTHERODON MELANOTHERON

This study conducted a baseline environmental audit of a proposed modular refinery site in Bayelsa State, Nigeria, utilizing the testis of the black chin tilapia (Sarotherodon melanotheron) as a bioindicator of potential environmental contamination. Surface water and sediment samples were collected from three locations: ARAC (control site), Obiama (proximal to the proposed site), and Sabatoru (distal to the proposed site). Various physicochemical parameters of water and heavy metal/Polycyclic Aromatic Hydrocarbon (PAH) concentrations in water and sediment were analyzed and compared against national and international (USEPA) guidelines. Additionally, heavy metal and PAH bioaccumulation in the testes of Sarotherodon melanotheron collected from the same sites were quantified. Furthermore, the fish health status was assessed through the Water Quality Index (WQI), Surface Water Quality Index (SWQI), condition factor, and histopathological examination of the testes. The results revealed that while the WQI and SWQI indicated "Good"water quality across all sites, several physicochemical parameters in the surface water, including temperature, dissolved oxygen, pH, copper, cadmium, nickel, chromium, and PAH, exceeded the recommended guidelines at Obiama and Sabatoru. Sediment analysis showed elevated levels of lead, cadmium, copper, nickel, chromium, and PAH across all sites compared to national guidelines, with the highest concentrations generally observed at Sabatoru. Bioaccumulation analysis in the fish testes demonstrated significant accumulation of lead, cadmium, and copper in fish from Obiama and Sabatoru compared to the control site (ARAC) (p 0.05). The fish health assessment indicated a significantly lower condition factor in fish from Obiama compared to ARAC (p 0.05). In conclusion, the baseline environmental audit revealed evidence of existing heavy metal and PAH contamination in the surface water and sediment of the proposed modular refinery site and the adjacent areas. The bioaccumulation of these contaminants in the testes of Sarotherodon melanotheron, coupled with the observed histopathological alterations and reduced condition factor in fish from Obiama and Sabatoru, suggests potential adverse environmental impacts even before the commencement of refinery operations. This study highlights the sensitivity of Sarotherodon melanotheron testis as a bioindicator and underscores the need for comprehensive Environmental Impact Assessment (EIA) and stringent pollution control measures prior to the establishment and operation of the proposed modular refinery to mitigate potential ecological risks in the sensitive Niger Delta ecosystem.