Petroleum hydrocarbon contamination assessment and characterization of three quagmire soils in the Gassi El Agreb oil field (Hassi Messaoud, Algeria)

The aims of the current study are the physicochemical characterization, spatial assessment and monitoring of hydrocarbon contamination in quagmire of three sites (Agreb, Gassi and Zotti) in the Hassi Messaoud region (Algerian Sahara), as a result of the presence of an important oil industry rejecting industrial wastewater. Samples were obtained from three different depths for each site. Total Hydrocarbons (THC) were determined by a gravimetric method, and the four (F1:C6-C10), (F2:C10-C16), (F3:C16-C34) and F4>C34) hydrocarbon fractions and BTEX (Benzene, Toluene, Ethyl-benzene and Xylene) were determined by using gas chromatography (FID). The results obtained show a high contamination with hydrocarbons in different sites and depths. The concentrations of THC, four hydrocarbon fraction and BTEX recorded on Agreb site in different depth were in this order: 51200-120000 mg/kg d.w.; <LOD - 59500 mg/kg d.w.; 2.4-90.8 mg/kg d.w. respectively; and for Gassi site, in this order: 59600-70300 mg/kg d.w.; < LOD - 43000 mg/kg d.w.; 8.5-112 mg/kg d.w. Finely they were in the following order: 18100-19200 mg/kg d.w.; <LOD - 9130 mg/kg d.w.; 2.75-65 mg/kg d.w. for Zotti site. Statistical analysis demonstrated an important site effect of THC and the three hydrocarbon fractions except for F4. However, there is no site and depth effect for BTEX. On the other hand the depth effect is significant just for THC, F1 and F2 of hydrocarbons. This variation can be attributed to the difference of physicochemical parameters between studied sites.