Ecological risk assessment using heavy metals from surface sediments of Nayband Bay and Asaluyeh region (Northern Persian Gulf)

The toxicity of heavy metals in sediments of the Nayband Bay and Asaluyeh region and potential ecological risk to sediment organisms assessed. Three stations with different degrees of vulnerability of South Pars Oil and Gas Activities (1: Control - 2: medium affected and 3: severely affected) were selected in the study area. Sediment sampling at each station in both cold and hot seasons (2010) were done by Van veen grab. Heavy metal concentration in sediment samples were investigated after the process of digestion and measured by atomic absorbtion. In order to assess the Sediment quality and ecological risk assessment of potential contamination, Contamination Factor (Cf) and Contamination Degree (Cd) were used for heavy metals and sediment, respectively. Finally the risk index was calculated. The highest levels of mercury in stations 3 and Ni, Pb and Zn were measured at Station 1. The maximum amounts of cadmium and copper were observed at station 2. The Most mercury contamination factor value and the least for nickel were obtained at Station 3.The degree of contamination for different stations from the total metal pollution factor was calculated. The maximum contamination level for Station 3 with the amount of 4.51 was obtained. Results showed that, mercury concentrations in the Nayband Bay and Asaluyeh region is upper-middle. Potential ecological risk (Eri), in the case of all metals except mercury, were in low ecological risk. Potential ecological risk of mercury was in very high ecological risk. The three stations were in the most severe ecological risks.