Methods are developed to use data collected during cyclic operation of soil vapor extraction (SVE) systems to help characterize the magnitudes and timescales of mass flux associated with vadose zone contaminant sources. Operational data collected at the Department of Energy's Hanford site are used to illustrate the use of such data. An analysis was conducted of carbon tetrachloride vapor concentrations collected during and between SVE operations. The objective of the analysis was to evaluate changes in concentrations measured during periods of operation and non-operation of SVE, with a focus on quantifying temporal dynamics of the vadose zone contaminant mass flux, and associated source strength. Three mass-flux terms, representing mass flux during the initial period of a SVE cycle, during the asymptotic period of a cycle, and during the rebound period, were calculated and compared. It was shown that it is possible to use the data to estimate time frames for effective operation of an SVE system if a sufficient set of historical cyclic operational data exists. This information could then be used to help evaluate changes in SVE operations, including system closure. The mass-flux data would also be useful for risk assessments of the impact of vadose-zone sources on groundwater contamination or vapor intrusion.

中文翻译：

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分析土壤蒸汽提取数据以评估质量传递约束和估计源区质量通量。

开发了方法来使用在土壤蒸汽提取 (SVE) 系统循环运行期间收集的数据，以帮助表征与包气带污染物源相关的质量通量的大小和时间尺度。在能源部汉福德站点收集的运营数据用于说明此类数据的使用。对在 SVE 操作期间和之间收集的四氯化碳蒸汽浓度进行了分析。分析的目的是评估 SVE 运行和非运行期间测得的浓度变化，重点是量化包气带污染物质量通量的时间动态以及相关的源强度。三个质量通量项，表示 SVE 循环初始阶段和循环渐近期间的质量通量，并在反弹期间，进行计算和比较。结果表明，如果存在足够的历史循环运行数据集，则可以使用这些数据来估计 SVE 系统有效运行的时间范围。然后可以使用此信息来帮助评估 SVE 操作的变化，包括系统关闭。质量通量数据也可用于对包气带源对地下水污染或蒸汽侵入的影响进行风险评估。