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Field and modeling studies of soil vapor migration into buildings at petroleum hydrocarbon impacted sites.

机译：土壤蒸气迁移到受石油烃影响的场所进入建筑物的现场和模型研究。

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摘要

The soil gas-to-indoor air "vapor intrusion" pathway is a possible human health exposure route at contaminated soil and groundwater sites, and regulatory agencies have developed pathway assessment guidance requiring indoor air, soil gas, and groundwater sampling. This guidance, however, has been based on an incomplete understanding of spatial and temporal variation in subsurface soil gas concentrations and temporal variation in indoor air concentrations. This research focused on those two topics. The former was addressed through a year-long, high density (in time and space) monitoring of soil gas hydrocarbon, oxygen, and carbon dioxide concentrations and soil gas/indoor differential pressure beneath and around a slab-on-grade building overlying shallow hydrocarbon-impacted soils. The latter was studied through numerical simulation. At the field site, there was spatial variability of up to two orders-of-magnitude in hydrocarbon and oxygen concentrations. A spectrum of temporal concentration behaviors was also observed, ranging from little change at source zone depths to changes on daily and hourly frequencies, with the highest frequency changes occurring near a foundation crack. Local oxygen supply (as dictated by wind speed, wind direction, position, subsurface features, and foundation cracks) and the depth to petroleum-impacted soils appeared to be the dominant factors controlling the observed behaviors. Computer simulations investigated three issues: (a) the effect of steady wind speed and direction and the resulting non-uniform soil gas pressure surface boundary condition about a building on steady soil gas distributions, (b) temporal changes in indoor air concentration induced by changing barometric pressure and wind speed, and (c) the relationship between sample collection duration and the ability to characterize time-varying indoor air quality. Simulation results suggest that steady winds at typical speeds can cause significant changes in sub-foundation soil gas distributions, relative to the case of similar building under-pressurization and a uniform surface pressure. Transient simulations using sinusoidal barometric pressure changes suggest indoor air concentration variations of more than 10 times in some cases, while exploratory simulations using actual field barometric pressure and wind speeds as inputs suggest temporal variations of up to three orders-of-magnitudes in instantaneous indoor air concentrations.
机译：从土壤气体到室内空气的“蒸气侵入”途径可能是在受污染的土壤和地下水场所暴露于人类健康的途径，监管机构已经制定了途径评估指南，要求对室内空气，土壤气体和地下水进行采样。但是，该指导基于对地下土壤气体浓度的时空变化和室内空气浓度的时空变化的不完全了解。这项研究集中在这两个主题上。前者的解决方法是对覆盖浅层碳氢化合物的地下平板建筑下方和周围的土壤气体碳氢化合物，氧气和二氧化碳浓度以及土壤气体/室内压差进行长达一年的高密度监测（在时间和空间上）受影响的土壤。通过数值模拟研究了后者。在现场，碳氢化合物和氧气浓度的空间变异性最高可达两个数量级。还观察到了一系列的时间集中行为，从源区深度的微小变化到每日和每小时的频率变化，最高的频率变化发生在地基裂缝附近。局部供氧量（由风速，风向，位置，地下特征和地基裂缝决定）和受石油影响的土壤深度似乎是控制观测行为的主要因素。计算机仿真研究了三个问题：（a）建筑物的稳定风速和风向以及由此产生的不均匀的土壤气压表面边界条件对稳定的土壤气体分布的影响；（b）由变化引起的室内空气浓度随时间的变化大气压力和风速，以及（c）采样时间与表征室内空气质量随时间变化的能力之间的关系。仿真结果表明，相对于类似建筑物压力不足和表面压力均匀的情况，稳定风速以典型速度会导致子基础土壤气体分布发生重大变化。使用正弦大气压变化的瞬态模拟表明，在某些情况下，室内空气浓度变化超过10倍；而使用实际大气压和风速作为输入的探索性模拟表明，瞬时室内空气的时间变化最多为三个数量级。浓度。

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  • 作者

    Luo, Hong.;

  • 作者单位

    Arizona State University.;

  • 授予单位 Arizona State University.;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 289 p.
  • 总页数 289
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 环境污染及其防治;
  • 关键词

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