Abstract：
The vertical distribution of 35 volatile organic compounds (VOCs) was investigated in soil columns from two obsolete industrial sites in Eastern China. The total concentrations of ΣVOCs in surface soils (0-20 cm) were 134-1664 ng g-1. Contamination of VOCs in surface soil exhibited remarkable variability, closely related to previous production activities at the sampling sites. Additionally, the concentrations of ΣVOCs varied with increasing soil depth from 0 to 10 m. Soils at depth of 2 m showed ΣVOCs concentrations of 127-47,389 ng g-1. Among the studied VOCs, xylene was the predominant contaminant in subsoils (2 m), with concentrations ranging from n.d. to 45,400 ng g-1. Chlorinated alkanes and olefins demonstrated a greater downward migration ability compared to monoaromatic hydrocarbons, likely due to their lower hydrophobicity. As a result, this vertical distribution of VOCs led to a high ecological risk in both the surface and deep soil. Notably, the risk quotient (RQ) of xylene in subsoil (2 m, RQ up to 319) was much higher than that in surface soil. Furthermore, distinct effects of VOCs on soil microbes were observed under aerobic and anaerobic conditions. Specifically, after the 30-d incubation of xylene-contaminated soil, Ilumatobacter was enriched under aerobic condition, whereas Anaerolineaceae was enriched under anaerobic condition. Moreover, xylene contamination significantly affected methylotrophy and methanol oxidation functions for aerobic soil (t-test, p < 0.05). However, aromatic compound degradation and ammonification were significantly enhanced by xylene in anaerobic soil (t-test, p < 0.05). These findings suggest that specific VOC compound has distinct microbial ecological effects under different oxygen content conditions in soil. Therefore, when conducting soil risk assessments of VOCs, it is crucial to consider their ecological effects at different soil depths.
摘要：
研究了中国东部两个过时工业地点的土壤柱中35种挥发性有机化合物（VOCs）的垂直分布。表层土壤（0-20cm）中ΣVOC的总浓度为134-1664ngg-1。表层土壤中挥发性有机化合物的污染表现出显著的变异性，与采样点以前的生产活动密切相关。此外,ΣVOC的浓度随土壤深度从0到10m而变化。深度为2m的土壤显示ΣVOC浓度为127-47,389ngg-1。在研究的挥发性有机化合物中，二甲苯是底土(2m)中的主要污染物，浓度范围从n.d.到45,400ngg-1。与单芳烃相比，氯化烷烃和烯烃表现出更大的向下迁移能力，可能是由于它们的疏水性较低。因此,VOCs的这种垂直分布导致地表和深层土壤的高生态风险。值得注意的是,底土中二甲苯的风险商(RQ)(2m，RQ高达319）远高于表层土壤。此外，在好氧和厌氧条件下，VOCs对土壤微生物的影响明显。具体来说,二甲苯污染土壤培养30天后，在好氧条件下富集Iumatobacter，而Anaerolineaceae在厌氧条件下富集。此外，二甲苯污染显著影响好氧土壤的甲基化和甲醇氧化功能(t检验，p<0.05)。然而,厌氧土壤中二甲苯显著增强了芳香族化合物的降解和氨化作用(t检验，p<0.05)。这些发现表明，特定的VOC化合物在土壤中不同的氧含量条件下具有明显的微生物生态效应。因此,在进行挥发性有机化合物的土壤风险评估时，考虑它们在不同土壤深度的生态效应是至关重要的。
