Modelling the influence of solution-enhanced conduits on catchment-scale contaminant transport in the Hertfordshire Chalk aquifer
Modelling the influence of solution-enhanced conduits on catchment-scale contaminant transport in the Hertfordshire Chalk aquifer
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模拟溶液增强管道对赫特福德郡白垩含水层流域规模污染物输送的影响
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
R. Sage
中科院分区：
文献类型：
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作者：
S. Cook;C. Fitzpatrick;W. Burgess;L. Lytton;P. Bishop;R. Sage
摘要 赫特福德郡白垩含水层受到来自圣奥尔本斯北部废弃工业场地的溴酸盐的流域规模（>40平方公里）污染，是英国发生的最大规模的点源地下水污染事件。 “双孔隙”扩散交换和沿溶液增强管道快速传输的影响使污染物传输到受威胁的公共供应井的预测模型变得复杂。示踪剂测试表明，溶液增强的流动路线存在于赫特福德郡溶解特征的表面分布之外，比之前想象的更广泛。对这种流动系统的定量概念理解已纳入 MODFLOW 和 MT3D-MS 中的空间分布等效多孔介质表示中。校准模型再现了含水层系统的基本特征，包括水头和流量、季节响应以及在溶液增强含水层中观察到的示踪剂突破的时间和空间分布，但没有完全捕获示踪剂和溴酸盐前进的幅度和形式。由于局部解增强和基体效应的影响，受体的细节突破无法在粗网格尺度上解析。然而，该模型能够模拟总体趋势。
Abstract Catchment-scale (>40 km2) contamination of the Chalk aquifer of Hertfordshire by bromate, emanating from a disused industrial site north of St Albans, represents the largest occurrence of point-source groundwater contamination in the UK. The influences of ‘double porosity’ diffusive exchange and rapid transport along solution-enhanced conduits complicate predictive modelling of contaminant transport to threatened public supply wells. Tracer testing indicates that solution-enhanced flow routes exist beyond the surface distribution of dissolution features in Hertfordshire, more extensively than previously thought. A quantitative conceptual understanding of this flow system has been incorporated into a spatially distributed equivalent porous media representation in MODFLOW and MT3D-MS. The calibrated model reproduces essential features of the aquifer system, including heads and flows, seasonal responses, and the timing and spatial distribution of observed tracer breakthroughs in the solution-enhanced aquifer, but does not fully capture the magnitude and form of tracer and bromate advance. Due to the influence of local solution enhancement and matrix effects, detailed breakthroughs at receptors cannot be resolved at the coarse grid scale. However, the model is able to simulate general trends.