Polycyclic aromatic hydrocarbons in agricultural soils from Northwest Fujian, Southeast China: Spatial distribution, source apportionment, and toxicity evaluation

摘要

Polycyclic aromatic hydrocarbons (PAHs) in agricultural soils play an important role in aspects of environment safety and human health. Sixteen US-EPA priority PAHs in 78 surface agricultural soils from Nanping and Sanming, Northwest Fujian were detected to elucidate their contamination levels, spatial distribution, sources, and toxicities. The total concentrations of PAHs were 12.90-2271.03 ng/g, with an average of 223.85 +/- 324.33 ng/g. North and Central Nanping and Central Sanming were found to be most contaminated regions in Northwest Fujian. The spatial distribution of PAHs positively correlated with the population density in the study area. Three- and four-ring PAHs were dominant components, accounting for 45% and 34% of the total PAHs, respectively. Four sources were identified by the positive matrix factorization (PMF) model. Their contributions to the total PAHs burden were 50%, 31%, 16%, and 3% for biomass combustion, coal burning, vehicle emission, and coking, respectively. Spatial distribution of sources indicated that higher amounts of biomass-originated PAHs mainly occurred in Sanming, while higher contributions of PAHs originated from coal burning and vehicular emission were mostly found in Nanping. The mean benzo(a)pyrene equivalent (BaPeq ) values were 14.95 ng/g for seven carcinogenic PAHs (Sigma(7)cPAH), and 15.20 ng/g for 16 PAHs, respectively, suggesting that Sigma(7)cPAH were the major toxic contributors to the total PAHs. Source apportionment of PAH toxicities based on PMF-BaPeq method showed that biomass, coal burning, vehicle emission, and coking source contributed 3%, 41%, 55%, and 1% to Sigma 16BaPeq values, respectively. Traffic source, associated with higher carcinogenic PAHs burden, posed the highest toxicity among all sources despite its low proportion of the total PAHs.