Simulating the effect of aerobic biodegradation on soil vapor intrusion into buildings: Influence of degradation rate, source concentration, and depth
Simulating the effect of aerobic biodegradation on soil vapor intrusion into buildings: Influence of degradation rate, source concentration, and depth
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DOI：
10.1021/es051335p
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发表时间：
2006-04-01
影响因子：
11.4
通讯作者：
Johnson, PC
中科院分区：
文献类型：
--
作者：
Abreu, LDV;Johnson, PC
使用三维多组分数值模型研究了涉及需氧生物降解化学品的稳态蒸汽入侵场景。在这些场景中，需氧可生物降解化学蒸气源放置在 10 m x 10 m 地下室或地面建筑建筑物下方 1-14 m 深处，并模拟碳氢化合物和氧气蒸气的同时传输和反应。结果以 Johnson 和 Ettinger 衰减因子 α（预测的室内空气碳氢化合物浓度/源蒸汽浓度）以及碳氢化合物和氧气浓度的归一化等高线图表示。除了改变蒸气源深度外，还研究了源浓度（2-200 mg化学品/L蒸气）和氧限制一级反应速率（10.018-1.8 h(-1)）的影响。尽管相关特性与一系列感兴趣的碳氢化合物相似，但碳氢化合物输入是苯所特有的。总体而言，结果表明，好氧生物降解可以在减少蒸汽侵入建筑物方面发挥重要作用（相对于无生物降解情况，α值降低），好氧生物降解的重要性随着蒸汽源深度的增加、蒸汽源浓度的降低和一级生物降解率的增加而增加。与无生物降解情况相比，在某些情况下，基础施工的差异可能很大。好氧生物降解的重要性生物降解与氧气能够迁移到地基下方的程度直接相关，例如，在 3 m bgs 处具有 200 mg/L 蒸气源的地下室情况下，氧气在迁移到地基下方之前就被消耗了，因此对于所研究的所有一阶速率，有氧生物降解和无需氧生物降解的模拟的衰减因子都是相似的，氧气为广泛分布在地基下方，生物降解情况的衰减因子比非生物降解情况小约 3 至 18 个数量级。
Steady-state vapor intrusion scenarios involving aerobically biodegradable chemicals are studied using a three-dimensional multicomponent numerical model. In these scenarios, sources of aerobically biodegradable chemical vapors are placed at depths of 1-14 m beneath a 10 m x 10 m basement or slab-on-grade construction building, and the simultaneous transport and reaction of hydrocarbon and oxygen vapors are simulated. The results are presented as Johnson and Ettinger attenuation factors alpha (predicted indoor air hydrocarbon concentration/source vapor concentration), and normalized contour plots of hydrocarbon and oxygen concentrations. In addition to varying the vapor source depth, the effects of source concentration (2-200 mg chemical/L vapor) and oxygen-limited first-order reaction rates 10.018-1.8 h(-1)) are studied. Hydrocarbon inputs were specific to benzene, although the relevant properties are similar to those for a range of hydrocarbons of interest. Overall, the results suggest that aerobic biodegradation could play a significant role in reducing vapor intrusion into buildings (decreased (alpha-values) relative to the no-biodegradation case, with the significance of aerobic biodegradation increasing with increasing vapor source depth, decreasing vapor source concentration, and increasing first-order biodegradation rate. In contrast to the no-biodegradation case, differences in foundation construction can be significant in some settings. The significance of aerobic biodegradation is directly related to the extent to which oxygen is capable of migrating beneath the foundation. For example, in the case of a basement scenario with a 200 mg/L vapor source located at 3 m bgs, oxygen is consumed before it can migrate beneath the foundation, so the attenuation factors for simulations with and without aerobic biodegradation are similar for all first-order rates studied. For the case of a 2 mg/L vapor source located at 8 m bgs, the oxygen is widely distributed beneath the foundation, and the attenuation factor for the biodegradation case ranges from about 3 to 18 orders-of-magnitude less than that for the no-biodegradation case.