van der Grift Bas, Griffioen Jasper
TNO Geological Survey of the Netherlands P.O. Box 80.015, 3508 TA Utrecht, The Netherlands.
J Contam Hydrol. 2008 Feb 19;96(1-4):48-68. doi: 10.1016/j.jconhyd.2007.10.001. Epub 2007 Oct 18.
Historic emissions from ore smelters typically cause regional soil contamination. We developed a modelling approach to assess the impact of such contamination on groundwater and surface water load, coupling unsaturated zone leaching modelling with 3D groundwater transport modelling. Both historic and predictive modelling were performed, using a mass balance approach for three different catchments in the vicinity of three smelters. The catchments differ in their hydrology and geochemistry. The historic modelling results indicate that leaching to groundwater is spatially very heterogeneous due to variation in soil characteristics, in particular soil pH. In the saturated zone, cadmium is becoming strongly retarded due to strong sorption at neutral pH, even though the reactivity of the sandy sediments is low. A comparison between two datasets (from 1990 to 2002) on shallow groundwater and modelled concentrations provided a useful verification on the level of statistics of "homogeneous areas" (areas with comparable land use, soil type and geohydrological situation) instead of comparison at individual locations. While at individual locations observations and the model varies up to two orders of magnitude, for homogeneous areas, medians and ranges of measured concentrations and the model results are similar. A sensitivity analysis on metal input loads, groundwater composition and sediment geochemistry reveals that the best available information scenario based on the median value of input parameters for the model predicts the range in observed concentrations very well. However, the model results are sensitive to the sediment contents of the reactive components (organic matter, clay minerals and iron oxides). Uncertainty in metal input loads and groundwater chemistry are of lesser importance. Predictive modelling reveals a remarkable difference in geochemical and hydrological controls on subsurface metal transport at catchment-scale. Whether the surface water load will peak within a few decades or continue to increase until after 2050 depends on the dominant land use functions in the areas, their hydrology and geochemical build-up.
矿石冶炼厂的历史排放通常会导致区域土壤污染。我们开发了一种建模方法，通过将非饱和带淋溶建模与三维地下水运移建模相结合，来评估此类污染对地下水和地表水负荷的影响。利用质量平衡方法，对三个冶炼厂附近的三个不同集水区进行了历史建模和预测建模。这些集水区在水文和地球化学方面存在差异。历史建模结果表明，由于土壤特性（特别是土壤pH值）的变化，向地下水的淋溶在空间上非常不均匀。在饱和带，尽管砂质沉积物的反应性较低，但由于在中性pH值下的强烈吸附作用，镉的滞留作用很强。对两个浅地下水数据集（1990年至2002年）和模拟浓度进行比较，为“均质区域”（具有可比土地利用、土壤类型和水文地质状况的区域）的统计水平提供了有用的验证，而不是在个别地点进行比较。虽然在个别地点观测值与模型值相差高达两个数量级，但对于均质区域，实测浓度的中位数和范围与模型结果相似。对金属输入负荷、地下水成分和沉积物地球化学的敏感性分析表明，基于模型输入参数中位数的最佳可用信息情景能够很好地预测观测浓度的范围。然而，模型结果对反应性组分（有机质、粘土矿物和铁氧化物）的沉积物含量敏感。金属输入负荷和地下水化学的不确定性影响较小。预测建模揭示了集水区尺度下地下金属运移的地球化学和水文控制存在显著差异。地表水负荷是否会在几十年内达到峰值，还是会持续增加直到2050年以后，取决于该地区的主要土地利用功能、其水文和地球化学积累情况。
