Tracing of petroleum products in groundwater (upstream of Dez watershed to Dez dam) in order to develop a new method of risk assessment

The oil industry is one of the causes of environmental pollution by oil spills due to drilling and extraction. In case of oil leakage from oil wells to soil and then groundwater, it leads to the movement of pollutants and the spread of pollution by groundwater. In the study area, due to the existence of two oil fields, Qaleh Nar and Balaroud, upstream of Dez Dam and their inclined slope towards Dez Dam Lake, the possibility of spreading oil pollutants through groundwater to Dez Dam was investigated and the development of new risk assessment method was also performed. Water samples from groundwater and Dez dam reservoir were analyzed for total petroleum hydrocarbon concentration. A Gas Chromatograph (GC-FID) was used to measure the concentration of TPH in samples. The probability of carcinogenic and non-carcinogenic diseases has been assessed according to the EPA standard. The results revealed non-carcinogenic risk (HQ) in groundwater and in Dez reservoir respectively with the highest C10 values of 38.54 mu g/ml and 1.9 mu g/ml. The new equation was formulated with the factor of importance and C10 was taken as the most important pollutant. The results of new method (HRA) indicated non-carcinogenic risk for C10 was highest in groundwater (well: 20.7, spring 1:22.5, spring 2:8.4, and spring 3:7.09 mu g/ml) and dam reservoir in sample C (1.1 mu g/ml), exceeding the safety limit of 0.6 (in the new formula). This study confirmed the entry of TPH into the reservoir of Dez Dam through groundwater and the risk of non-carcinogenic diseases.

Automated summary

The oil industry causes environmental pollution through oil spills, and this study investigates the possibility of oil pollutants spreading to a reservoir through groundwater and develops a new risk assessment method. The results show non-carcinogenic risks in both groundwater and the reservoir, with C10 as the most important pollutant.