Occurrence, Distribution, and Variation of Polycyclic Aromatic Hydrocarbons in Water and Sediments in the Euphrates River between Haditha Dam and Hit City, Iraq

Due to their possible carcinogenic effects on natural ecosystems, polycyclic aromatic hydrocarbons are a prominent class of hazardous organic compounds that have recently attracted considerable attention. This research aims to determine the distribution, temporal extent, and spatial extent of Polycyclic aromatic hydrocarbon contamination in water and sediment of the Euphrates River between Haditha Dam and Hit City, Al-Anbar Governorate, Iraq. Six sites along the river were selected for river water sampling in January and August 2023 using gas chromatography. The results of the summation of polycyclic aromatic hydrocarbons in water samples ranged from 3.88-115.8 mg/L in August to 3.45-107.88 mg/l in January. The same locations were chosen to examine polycyclic aromatic hydrocarbons in sediment samples; the results showed that Polycyclic aromatic hydrocarbon concentrations ranged from 9.55 to 200.2 mg/L. The pyrogenic and petrogenic origins are the two expected origin patterns of the PAHs in the studied samples. The Hit site was a petrogenic source due to the interaction with hydrocarbon molecules from several sulfur springs near the city, whereas the other sites were of pyrogenic origin. Additionally, sites R1 and R5 had water and sediment that were of high pollution category. However, based on two indicators (low/high and Phenanthrene/Anthracene), the findings indicated that the sediment's Polycyclic aromatic hydrocarbon pollution came from pyrogenic sources linked to waste materials, high traffic density, and the impact of agricultural and human activities. Lastly, in both the wet and dry periods, the total minimum and maximum Polycyclic aromatic hydrocarbon in water samples in the study region exceeded the United States Environmental Protection Agency's recommended maximum contamination limits.