Evaluation of total concentration of petroleum hydrocarbons and heavy metals (lead, cadmium) in petroleum effluents

Oil pollution is an inevitable consequence of rapid population growth. Increasingly, large scale use of petroleum resources is one of the major causes of pollution. This study investigates contamination of petroleum hydrocarbons and single metals (lead, cadmium) in wastewater of Golestan Oil Company. Three stations were constructed at the effluent outlet of Oil Company. For each station, 20 bivalves were assigned to the net section. Atomic absorption spectroscopy was used to measure cadmium and lead metals and GC-Mass was used to measure total petroleum hydrocarbons. The results show that the annual mean total hydrocarbon concentration was 2.94 mg/l and the highest oil content in spring was 20.1 mg/l below market saturation which was several times higher. The global standard for the highest concentration of petroleum in the autumn has been measured at 0.01 mg/liter. Average annual heavy metal concentrations in the first station for cadmium in spring, summer, fall and winter were equal to 0.750, 0.556, 0.265 and 0.279, respectively, in the second station for cadmium in spring, summer, autumn and winter. At the third station, the levels of cadmium were 0.317, 0.2284, 0.192 and 0.179 at the third station. Also, the mean concentration of lead in spring, summer, fall and winter were 0.860, 0.721, 0.383 and 0.221, respectively, at the second station of cadmium concentration in spring, summer, fall and winter, respectively. In the third station, the amount of cadmium was 0.392, 0.436, 0.342 and 0.194, respectively. The output effluent of oil depots in Golestan province Petroleum Products Distribution Company is higher than international standards in terms of total petroleum hydrocarbons and heavy metals distribution.