Contents, sources and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in agricultural soils of plantations in northern Hainan Island

Hainan Island is the main planting base of tropical plants in China.Evaluating the level of soil pollution in this area has a great significance.In this study, we assessed the contamination levels, sources and ecological risk of 16 priority polycyclic aromatic hydrocarbons (PAHs) in agricultural soils of northern Hainan Island.A total of 100 surface soil samples were collected from plantations (coffee, banana, yam, sugarcane, orange, passion fruit and guava) and analyzed for PAHs concentration using gas chromatography equipped with a mass spectrometry detector (GC-MS).The average of ∑16PAHs from plantation soil was 37.6 ng/g, which was below the background of national soil and the no pollution limit of 200 ng/g determined by Netherlands.Three-, four- and five-ring PAHs were dominant components, accounting for 25.8%, 26.8% and 23.5% of the total PAHs, respectively.Source analysis suggested that PAHs of soil in these plantations were mainly derived from the exhaust gas of locomotives and partially from oil spill as well as low temperature combustion of coal and biomass.In ecological risk assessment, the benzo(a) pyrene equivalent concentration (∑16BaPeq) presented a much lower level than the guideline values announced by Chinese Environmental Protection Agency, demonstrating that the PAHs contamination level in solis was acceptable.