College of Geosciences, China University of Petroleum, Beijing 102249, China; State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
College of Geosciences, China University of Petroleum, Beijing 102249, China; State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China.
Environ Pollut. 2019 Nov;254(Pt A):112981. doi: 10.1016/j.envpol.2019.112981. Epub 2019 Jul 30.
The risk of soils transferring polycyclic aromatic hydrocarbons (PAHs) into groundwater has caused widespread concern. Research on the leaching behavior of PAHs in soil profiles is very important for assessing this risk. Column leaching tests were carried out to provide insight into the effect of TOC and leaching water volume on leaching behavior of PAHs. Four groups were leached intermittently by deionized water under the same leaching rate for 10 d, 30 d, 90 d and 120 d. These four leaching periods are equivalent to 1 yr, 3 yr, 9 yr and 12 yr of rainfall time under natural conditions, respectively. The results showed that residual concentrations of PAHs on the surface of soil (0-5 cm) in three columns after 30 d of leaching were 37.9 μg/g, 18.5 μg/g and 3.7 μg/g, respectively, which was consistent with their TOC contents. According to the correlation analysis, both residual concentrations of ∑PAHs and PAHs with different ring numbers were significantly correlated with the TOC content at depths of 5-100 cm after 30 d of leaching. With increased leaching water volume, PAH migration rates significantly decreased (from 3.13 μg/g/d to 0.005 μg/g/d) from 10 d to 120 d, which indicates that the initial period of the leaching process has a stronger effect on PAH vertical migration than the later stages of the process. Under long-term leaching, PAHs that were not leached previously were capable of migrating deeper into the soil profile. Therefore, it has the risk of PAH-contaminated soils transferring PAHs into groundwater.
土壤中多环芳烃（PAHs）向地下水迁移的风险引起了广泛关注。研究土壤剖面中 PAHs 的淋滤行为对于评估这种风险非常重要。通过柱淋滤试验，研究了 TOC 和淋滤水量对 PAHs 淋滤行为的影响。用去离子水在相同淋滤率下间歇淋滤 4 组，分别为 10、30、90 和 120 d。这四个淋滤期分别相当于自然条件下 1 年、3 年、9 年和 12 年的降雨量时间。结果表明，在淋滤 30 d 后，三个柱体表层土壤（0-5 cm）中 PAHs 的残留浓度分别为 37.9、18.5 和 3.7μg/g，与 TOC 含量一致。相关性分析表明，在淋滤 30 d 后，∑PAHs 和不同环数 PAHs 的残留浓度与 5-100 cm 深度的 TOC 含量均呈显著相关。随着淋滤水量的增加，PAH 的迁移率从 10 d 的 3.13μg/g/d 显著降低至 120 d 的 0.005μg/g/d，表明淋滤过程初期对 PAH 垂直迁移的影响比后期更强。在长期淋滤下，以前未淋滤出的 PAHs 能够更深地迁移到土壤剖面中。因此，有受 PAH 污染的土壤将 PAHs 转移到地下水的风险。
