Characterizing long-term contaminant mass discharge and the relationship between reductions in discharge and reductions in mass for DNAPL source areas.
Characterizing long-term contaminant mass discharge and the relationship between reductions in discharge and reductions in mass for DNAPL source areas.
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DOI：
10.1016/j.jconhyd.2013.02.011
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发表时间：
2013-06
影响因子：
3.6
通讯作者：
Plaschke, M.
中科院分区：
文献类型：
--
作者：
Brusseau, M. L.;Matthieu, D. E., III;Carroll, K. C.;Mainhagu, J.;Morrison, C.;McMillan, A.;Russo, A.;Plaschke, M.
本研究的目的是表征污染物质量排放的时间行为，以及减少污染物质量排放和减少污染物质量之间的关系，为一个非常异质的，高度污染的源区现场。三氯乙烯是令人关切的主要污染物，若干证据表明地下存在有机液体。该场地正在进行地下水开采以进行源头控制，自系统启动以来一直对污染物排放进行监测。结果表明，随着时间的推移，污染物排放量显着减少，从约1至0.15公斤/天。两种方法被用来估计质量的污染物在污染源地区的补救项目开始时。一个是基于两组核心数据的比较，收集间隔3.5年，这表明，一个显着的减少（约80%），总沉积物相三氯乙烯浓度发生在采样事件之间。第二种方法是基于拟合的时间污染物质量排放数据与一个简单的指数源耗尽函数。用这两种方法得到的估计值相对相似，分别为784公斤和993公斤。这些数据被用来表征减少污染物质量排放（CMDR）和减少污染物质量（MR）之间的关系。所观察到的曲线关系表现出减少污染物质量排放基本上立即开始质量减少。这种行为是一致的系统，其中大量的质量是存在于液压差的访问域的质量去除是受限速传质。从本研究中获得的结果进行了比较，从其他领域的研究，以评估系统的性能和条件对质量放电和质量去除行为的影响。结果表明，如域规模，水力梯度状态（诱导或自然），和冲洗溶液的组合物的因素有CMDR-MR配置文件，从而对基本的质量去除行为的影响并不显著。相反，源区年龄，通过其对污染物分布和可及性的影响，被牵连作为一个关键因素影响的性质的CMDR-MR关系。
The objective of this study was to characterize the temporal behavior of contaminant mass discharge, and the relationship between reductions in contaminant mass discharge and reductions in contaminant mass, for a very heterogeneous, highly contaminated source-zone field site. Trichloroethene is the primary contaminant of concern, and several lines of evidence indicate the presence of organic liquid in the subsurface. The site is undergoing groundwater extraction for source control, and contaminant mass discharge has been monitored since system startup. The results show a significant reduction in contaminant mass discharge with time, decreasing from approximately 1 to 0.15 kg/d. Two methods were used to estimate the mass of contaminant present in the source area at the initiation of the remediation project. One was based on a comparison of two sets of core data, collected 3.5 years apart, which suggests that a significant (~80%) reduction in aggregate sediment-phase TCE concentrations occurred between sampling events. The second method was based on fitting the temporal contaminant mass discharge data with a simple exponential source-depletion function. Relatively similar estimates, 784 and 993 kg, respectively, were obtained with the two methods. These data were used to characterize the relationship between reductions in contaminant mass discharge (CMDR) and reductions in contaminant mass (MR). The observed curvilinear relationship exhibits a reduction in contaminant mass discharge essentially immediately upon initiation of mass reduction. This behavior is consistent with a system wherein significant quantities of mass are present in hydraulically poorly accessible domains for which mass removal is influenced by rate-limited mass transfer. The results obtained from the present study are compared to those obtained from other field studies to evaluate the impact of system properties and conditions on mass-discharge and mass-removal behavior. The results indicated that factors such as domain scale, hydraulic-gradient status (induced or natural), and flushing-solution composition had insignificant impact on the CMDR-MR profiles and thus on underlying mass-removal behavior. Conversely, source-zone age, through its impact on contaminant distribution and accessibility, was implicated as a critical factor influencing the nature of the CMDR-MR relationship.
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