PAHs and Pb heavy metal absorption by Dreissena polymorpha (Pallas, 1771) bivalve under oil pollution

The main purpose of this study was to find the absorption of Pb as heavy metal and cyclic aromatic hydrocarbons (PAHs) by Dreissena polymorpha under oil pollution. Totally, 130 samples with an average length range of 3.5±0.7 cm and average weight range of 25.5±3 g were collected from the Tajan River estuary in Mazandaran province and transferred to the laboratory. Three stations were considered (Station 1: Oil Company Wastewater (OCW), Station 2: Car Oil Change Wastewater (COCW), Station 3: Agricultural Pumping Canal (APC)). The amounts of PAHs and lead metal uptake by bivalves were measured during warm and cold water seasons. Tissue mass was isolated to measure PAHs at each station. In the cold season, the maximum concentration of lead was in the OCW station (0.762±0.01 mg/L) and the lowest concentration was observed in APC station (0.367±0.06 mg/L) (p<0.05). In the warm season, the highest concentration of Pb was observed in COCW station (0.558±0.02 mg/L) and the lowest was in APC station (0.376±0.01 mg/L). There was no significant difference between OCW and COCW stations in the cold season (p>0.05). Also, in the warm season, the highest concentration of Pb was observed in COCW station and the lowest concentration was in APC station (p<0.05). During the experiment period, the highest absorbed concentration of bivalves was recorded at OCW station (328.39 ±1.33 ng/dw) and the lowest concentration was in APC station (62.85±8.9 ng/dw). Moreover, there was a significant difference between PAHs concentration of OCW station with other stations (p<0.05). The concentration of the compounds measured in February was higher than in August due to the precipitation and flooding of the route to the bivalve stations. Heavy compounds were also more concentrated than lighter compounds. Finally, it can be concluded that this bivalve can be used as an appropriate biomarker for monitoring oil compounds in the environment.