Polycyclic aromatic hydrocarbons (PAHs) contamination of soils and water around automobile repair workshops in Eket metropolis, Akwa Ibom State, Nigeria

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are very toxic and persistent environmental contaminants. The paper is aimed at investigating the PAHs levels in soil collected at 0-30 cm depths from 5 automobile repair workshops within Eket metropolis/the underground water around its vicinity. The soils and water were prepared in the laboratory following standard procedures and were analysed for 16 US EPA priority PAHs using Gas Chromatography-Mass Spectrometer (GC-MS). Total PAHs concentrations in soil (Ʃ16 EPA PAHs) from all sampling sites were in the range of 0.82-12.98 mg/ kg and 0.47-14.85 mg/kg for both dry and rainy seasons respectively and did not follow regular pattern with depth. Total PAHs concentrations in underground water from all sampling sites were in the range of 1.71-16.07 mg/l and 1.07-12.97 mg/l for both dry and rainy seasons respectively. According to European commission contamination classification and WHO maximum permissible limit for PAHs in drinking water (0.002 mg/l), the sites are said to be moderately to heavily contaminated. The total BaPeq for the soil and water samples indicated a moderate carcinogenic burden and hence low health risk. The calculated values obtained from diagnostic ratios shows that the PAHs in this study were from both pyrogenic and petrogenic sources. The correlation between total PAHs concentration in soil and water for both seasons indicated that the automobile repair activities had a moderate effect on the soil as well as the underground water around it. Therefore, boreholes should not be sited close to automobile repair yards to enable its suitability for domestic, irrigation and recreational usage.

Ecological risk assessment of the levels of polycyclic aromatic hydrocarbons in soils of the abandoned sections of Orji Mechanic Village, Owerri, Imo State, Nigeria

“…Reports have shown that indiscriminate spilling of petroleum products around automechanic workshops due to automobile repairs contributes to increased PAH levels in such environment (Farombi et al 2013;Obini et al 2013;Nwoko et al 2017). The mean PAH concentrations of the present study compared to related studies in Nigeria revealed that higher PAH values were reported by Obini et al (2013), Ogoko (2014), and Ekanem et al (2019), while comparable values were reported by Muze et al (2020). The concentration of PAHs reported in the present study was lower than 1000 µg/kg recommended for soil cleanup by the Department of Petroleum resources, Nigeria (DPR 2002).…”

“…Previous publications have reported the presence of PAHs in mechanic villages and automobile workshops (Ogoko 2014;Ekanem et al 2019;Muze et al 2020). The six USEPA target PAHs including phenanthrene, fluorene, benzo [α]anthracene, benzo [β]fluoranthene, and benzo[γ]fluoranthene, with concentrations ranging from 0.0184 ± 0.02 to 0.1385 ± 0.2 mg/kg were observed in Abakaliki automechanic village (Obini et al 2013).…”

“…Pulverization of the soil samples was achieved with mortar and pestle made of porcelain and further sieved with 2-mm mesh. The level of PAHs contained in the soil samples was extracted according to standard procedures as described by previous publications (Paíga et al 2012;Jiao et al 2017;Ekanem et al 2019). In other to remove moisture in the soil samples, 10 g of each sample was weighed and mixed with another 10 g of dried sodium sulfate.…”

“…The effects of the activities of automobile mechanics in the Niger Delta area of Nigeria revealed elevated levels of Pb, Cd, TPH, and some PAHs (Muze et al2020). Also, the total PAH concentrations ranging from 0.47 to 14.85 mg/kg in soil samples collected from some automobile workshops in Akwa Ibom State, Nigeria, have been reported (Ekanem et al 2019).…”

<strong>Polycyclic Aromatic Hydrocarbon (PAH) Pollution and its Associated Human Health Risks in the Niger Delta Region of Nigeria: A Systematic Review</strong>

“…Due to the high levels of PAH pollution occurring in the Niger Delta and their associated health risks, several studies have been conducted by collecting samples from different environments of the Niger Delta. Most of these environments include rivers, creeks, dumpsites, OEE sites, automobile repair shops, agricultural farms, and other urban areas (Abbas and Brack 2005;Ana et al 2009;Sojinu et al 2010;Nganje et al 2011;Olawoyin et al 2012;Oyo-Ita et al 2012;Adedosu et al 2012;Osuji et al 2012;Nduka et al 2013;Nganje et al 2014;Ogoko 2014;Asagbra et al 2015;Inam et al 2015;Nwineewii and Marcus 2015;Davies and Abolude 2016;Dosunmu et al 2016;Nwaichi et al 2016;Ekanem et al 2019;Ihuoma et al 2020).…”