Zhang Juan, Fan Shukai, Du Xiaoming, Yang Juncheng, Wang Wenyan, Hou Hong
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Science, Beijing, China; School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing, China.
Environmental Engineering Institute, Beijing General Research Institute of Mining and Metallurgy, Beijing, China.
PLoS One. 2015 Feb 13;10(2):e0115863. doi: 10.1371/journal.pone.0115863. eCollection 2015.
Farmland soil and leafy vegetables accumulate more polycyclic aromatic hydrocarbons (PAHs) in suburban sites. In this study, 13 sampling areas were selected from vegetable fields in the outskirts of Xi'an, the largest city in northwestern China. The similarity of PAH composition in soil and vegetation was investigated through principal components analysis and redundancy analysis (RDA), rather than discrimination of PAH congeners from various sources. The toxic equivalent quantity of PAHs in soil ranged from 7 to 202 μg/kg d.w., with an average of 41 μg/kg d.w., which exceeded the agricultural/horticultural soil acceptance criteria for New Zealand. However, the cancer risk level posed by combined direct ingestion, dermal contact, inhalation of soil particles, and inhalation of surface soil vapor met the rigorous international criteria (1 × 10(-6)). The concentration of total PAHs was (1052 ± 73) μg/kg d.w. in vegetation (mean ± standard error). The cancer risks posed by ingestion of vegetation ranged from 2×10-5 to 2 × 10(-4) with an average of 1.66 × 10(-4), which was higher than international excess lifetime risk limits for carcinogens (1 × 10(-4)). The geochemical indices indicated that the PAHs in soil and vegetables were mainly from vehicle and crude oil combustion. Both the total PAHs in vegetation and bioconcentration factor for total PAHs (the ratio of total PAHs in vegetation to total PAHs in soil) increased with increasing pH as well as decreasing sand in soil. The total variation in distribution of PAHs in vegetation explained by those in soil reached 98% in RDA, which was statistically significant based on Monte Carlo permutation. Common pollution source and notable effects of soil contamination on vegetation would result in highly similar distribution of PAHs in soil and vegetation.
在郊区，农田土壤和叶菜类蔬菜积累了更多的多环芳烃（PAHs）。本研究从中国西北最大城市西安郊区的菜地中选取了13个采样区域。通过主成分分析和冗余分析（RDA）研究了土壤和植被中PAH组成的相似性，而非区分来自不同来源的PAH同系物。土壤中PAHs的毒性当量范围为7至202μg/kg干重，平均为41μg/kg干重，超过了新西兰农业/园艺土壤的验收标准。然而，通过直接摄入、皮肤接触、吸入土壤颗粒和吸入表层土壤蒸汽综合造成的癌症风险水平符合严格的国际标准（1×10⁻⁶）。植被中总PAHs的浓度为（1052±73）μg/kg干重（平均值±标准误差）。摄入植被造成的癌症风险范围为2×10⁻⁵至2×10⁻⁴，平均为1.66×10⁻⁴，高于国际致癌物终身超额风险限值（1×10⁻⁴）。地球化学指标表明，土壤和蔬菜中的PAHs主要来自车辆和原油燃烧。植被中总PAHs以及总PAHs的生物富集系数（植被中总PAHs与土壤中总PAHs的比值）均随着土壤pH值的升高以及土壤中砂含量的降低而增加。在冗余分析中，土壤中PAHs分布的总变化对植被中PAHs分布的解释率达到98%，基于蒙特卡洛排列检验具有统计学意义。共同的污染源以及土壤污染对植被的显著影响导致土壤和植被中PAHs的分布高度相似。
