Occurrence and source of some polycyclic aromatic hydrocarbons (PAHs) in surface sediment of Diwaniah and Daghara rivers /Iraq

Abstract

The distribution and possible sources of 16 polycyclic aromatic hydrocarbons (PAHs) were investigated in the surface sediments of Diwaniah and Daghara rivers in AL- Qadissiah province in Iraq during the period from March 2011 to February 2012, surface sediment samples were collected from four locations in Diwaniah, and Daghara river sited along rivers and other station on Hilla river which were branched from it. Sixteen PAHs were identified and quantified in sediments sample by High performance liquid chromatography (HPLC). Concentration of total PAHs ranged between (2.19--354.55ng/g dry weight)were recorded at St.1 on Hilla river during Aug. and St.5 on Diwaniah river through Mar. respectively. with annual mean concentrations of ΣPAH ranged between (37.4--90.7 ng/g) at Hilla river and St5 on Diwaniyah respectively. The maximum concentration of individual PAH were detected of Pyrene (96.9ng/g)at St.2 on Daghara river while some high molecular weight HMW such BaP ,IND and BkF no detected during some months . Compositional pattern analysis investigated that 2-3ring of individual PAHs was highest ratio in comparing with 4,5.6 ring whereas 6ring was lowest ratio in all stations. Diwaniah and Daghara rivers were moderately polluted by PAHs (Σ16PAH=250-500ng/g) while Hilla river was slightly polluted (Σ16PAH <250ng/g).
Diagnostic ratios suggested that possible source of PAHs were mixed sources among pyrogenic and petrogenic origin in the study region.
The results of current study showed that total organic carbon (TOC)in sediment sample ranged between (0.2-3.2%) at Hilla and Diwaniah rivers also respectively, Grain size distribution test illustrated that sandy nature was abundant in all stations. PAHs do not correlate with the particle size distributions but it significant correlated with the content of the TOC in sediment.