Origin and sources of polycyclic aromatic hydrocarbons (PAHs) in sediments core from Tigris, Euphrates and Shatt Al-Arab rivers

Due to the important area of the Tigris, Euphrates and Shatt Al-Arab rivers in Iraq, and the effect of pollutant to theses rivers, the object of study is the origin and sources of PAHs compounds in sediment core samples which collected in 2021 from six important stations that are (Tigris1, Tigris2, Euphrates1, Euphrates2, Shatt Al-Arab1, and Shatt Al-Arab2). Polycyclic aromatic hydrocarbons (PAHs) were analyzes by using capillary gas chromatography. The results of PAHs shown in two pattern low and high molecular weight. The total PAHs ranged between 79.141 ng/g at station No. 6 to 3.830 ng/g at station No. 3. The rush to develop industries across the globe accelerates environmental damage brought on by many contaminants, including PAHs. Organic compounds in the PAHs class have two or more aromatic rings. PAHs can be pyrogenic, petrogenic, or biogenic depending on how they develop. Pyrogenic PAHs are produced when various fuels, oil and gas, waste, or other organic materials like fume from oil industries in the area. The investigation showed two patterns of sources petrogenic and pyrogenic with the petrogenic source predominating according to the ratios (low molecular weight/high molecular weight), anthracene/(anthracene+phenanthrene) and fluoranthene/(fluoranthene+pyrene). Additionally, findings indicated that sediment pollution is of a moderate pollution. By adhering to sedimentary particles, PAHs get into the sediments. Based on the physicochemical characteristics of each fraction and the surrounding environment, sediments also serve as a source for some contaminants that re-enter the water column. Lighter PAHs predominated in water samples, while heavier compounds predominated in sediment samples, according to several studies. In addition, it is difficult to remove the high concentrations of PAHs in riverine sediments brought on by industrial activity. While other research indicated significant PAHs pollution in a variety of global environments. Due to the fact that such research helps to lessen the obvious shortage of information regarding such pollutants in Iraqi rivers, this study gives as the baselines for coming research.