Distribution and sources of polycyclic aromatic hydrocarbons in soils along the Shatt Al-Arab River Delta in southern Iraq

Abstract

The soil samples from 0–10 cm depth were collected from three areas (Center of Basrah – CB, Garmat Ali – GA, and Abu Al-Khasib – AK) located along the Shatt Al-Arab River (SR) delta in southern Iraq to estimate the distribution and sources of polycyclic aromatic hydrocarbons (PAHs). The PAH total concentrations in the soils decreased significantly from CB (72.16 ng/g dry weight (DW)), GA (36.48 ng/g DW), to AK (17.30 ng/g DW) gradually indicating the impact of pollution emissions on the distribution of PAHs in soils. The low (2 and 3 ring) and high (4, 5, and 6 ring) molecular weight PAHs accounted for 14%, 16%, 37%, 21%, and 12% respectively in CB soil, 24%, 31%, 29%, 7%, and 10% in GA soil and 40%, 29%, 17%, 8%, and 8% in AK soil. The high molecular weight PAHs predominated in CB soils and the low molecular weight PAHs dominated in GA and AK soils suggesting a difference in emission sources between the studied areas. The PAH diagnostic ratios and principal component analysis (PCA) indicated that PAHs in soils of the SR delta essentially originated from traffic and industrial emissions and biomass and grass/wood/coal combustion. The PAH atmospheric transport from CB area might impact the PAH distribution in the soils of AK area. The risk assessment of the soils has been performed. The total toxic equivalent concentrations (Bap<sub>teq</sub>) of PAHs in the examined areas did not exceed the Dutch target values suggesting that no carcinogenic risk for the SR delta soils was found.

Using Toxic Equivalent Quotients (TEQs) to Evaluate the Risk of Polycyclic Aromatic Hydrocarbons Compounds in Soil at Basrah Governorate, Iraq

“…The present results were in agreement with other reports. (Al-Saad et al, 2017;Al-Saad et al, 2019).…”

“…The study area is located at Basrah governorate, southern Iraq. Basrah covers an area of (19,070 km 2 ) and has a population of (2.532 million people) (Al-Saad et al, 2019). The studied stations are distributed from north to south at Basrah governorate, divided into thirty stations distributed in eight different land uses that included (five residential areas, four…”

“…To determine the carcinogenicity possibility associated with exposure to individual and total PAH compounds, the (TEQs) was calculated depending on the toxic equivalent factor (TEF) of each individual PAH. The (TEQs) was calculated using the following equation (Qiao et al, 2006;Al-Saad et al, 2019;Cao et al, 2019;Li et al, 2020):…”

“…TEFi: toxic equivalent factor of each PAH compound as showed in table (1) according to (Qiao et al, 2006;Al-Saad et al, 2019).…”

Assessment of Polycyclic Aromatic Hydrocarbons in Agricultural Soils of Teskelewu Community and Environs Impacted By Gas Flaring in Delta State, Nigeria

“…Formation of PAH is due to incomplete combustion of organic matter through the condensation of ethylenic radicals in the gas phase to form the larger polycyclic compounds (Lane, 1989). PAHs may originate from natural sources (PAH background values) such as forest fires, volcanic activity or as a result of anthropogenic activities like incomplete combustion of fossil fuels and industrial emissions (Al-Saad et al, 2019). PAHs found in the urban environment are predominantly anthropogenic in origin.…”