Polycyclic Aromatic Hydrocarbons (PAHs) in the Soil of West Qurna-2 Oil Field Southern Iraq

Abstract

This study focused on the determinate concentrations of polycyclic aromatic hydrocarbon by using capillary gas chromatographic for soil of ten stations in West Qurna-2 oil field. The first included light (low molecular weight) compounds with two-three fused aromatic rings which consisting of: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, and carbazole. The second included the heavy (high molecular weight) compounds with  four or more fused aromatic rings consisting of: floranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)flouranthene, benzo(k)flouranthene, benzo(a)pyrene,  indeno(1,2,3,c,d)pyrene, dibenzo(a,h)anthracene, and benzo(g,h,i)perylene. The dominant light PAHs compounds were acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene and carbazol. Whereas the dominant heavy PAHs compounds were floranthene, pyrene, benzo(a)pyrene , benzo(a)anthracene , benzo(k)flouranthene. The regional higher mean concentrations of PAHs in station 10 was (5.906 ng/g) and the lowest in station 1 (1.125 ng/g). The results of seasonal PAHs concentration in this study showed that the lowest concentrations recorded during summer (1.214 ng/g), while the highest concentrations recorded during winter (4.177ng/g). From the LMW/HMW, phenanthrene/anthracene and benzo(a)anthracene/benzo(a)anthracene+ chrysene ratios, the PAHs compound was drived from pyrogenic sources, while Flouranthene/Pyrene Ratio and InP/(InP+BghiP) Ratio was pyrogenic+ petrogenic origin and petrogenic or pyrogenic and Ant/(Ant+ Phen) Ratio was pyrolytic. Concentrations in studied stations gradually increased from station 1 to station 5, and then significantly decreased at station 6 and finally increased to station 10. The fluctuation in concentrations of compound at stations is due to distance from the flame of the flare which near to the stations 8,9,10 and far to the stations 1,2,3,4,5,6,7, while the seasonal concentration arrange as following: winter >spring >autumn>summer. There were non-significant correlation between the PAHs in soil and each of the soil texture compounds (sand, silt and clay), while there is significant correlation between the PAHs in soil and TOC%.