Department of Physical Geography, Bolin Centre for Climate Research, Stockholm University, SE-106 91 Stockholm, Sweden.
Environmental Department, Swedish National Road and Transport Research Institute (VTI), Box 8072, SE-402 78 Gothenburg, Sweden; Architecture and Civil Engineering, Chalmers University, SE-412 96 Gothenburg, Sweden.
Sci Total Environ. 2020 Apr 10;712:135560. doi: 10.1016/j.scitotenv.2019.135560. Epub 2019 Nov 17.
Heavy metal and metalloid contamination of topsoils from atmospheric deposition and release from landfills, agriculture, and industries is a widespread problem that is estimated to affect >50% of the EU's land surface. Influx of contaminants from soil to groundwater and their further downstream spread and impact on drinking water quality constitute a main exposure risk to humans. There is increasing concern that the present contaminant loading of groundwater and surface water systems may be altered, and potentially aggravated, by ongoing climate change, through large-scale impacts on recharge and groundwater levels. We investigated this issue by performing hydrogeological-geochemical model projections of changes in metal(loid) (As and Pb) mobilization in response to possible (climate-driven) future shifts in groundwater level and fluctuation amplitudes. We used observed initial conditions and boundary conditions for contaminated soils in the temperate climate zone. The results showed that relatively modest increases (0.2 m) in average levels of shallow groundwater systems, which may occur in Northern Europe within the coming two decades, can increase mass flows of metals through groundwater by a factor of 2-10. There is a similar risk of increased metal mobilization in regions subject to increased (seasonal or event-scale) amplitude of groundwater levels fluctuations. Neglecting groundwater level dynamics in predictive models can thus lead to considerable and systematic underestimation of metal mobilization and future changes. More generally, our results suggest that the key to quantifying impacts of climate change on metal mobilization is to understand how the contact between groundwater and the highly water-conducting and geochemically heterogeneous topsoil layers will change in the future.
重金属和类金属污染物来自大气沉降和垃圾填埋场、农业和工业的释放，已对欧盟超过 50%的土地表面造成污染，这是一个普遍存在的问题。污染物从土壤向地下水的迁移及其下游的进一步扩散，并对饮用水质量造成影响，这对人类构成了主要的暴露风险。人们越来越担心，由于大规模影响补给和地下水水位，当前地下水和地表水系统的污染物负荷可能会发生变化，并可能因气候变化而加剧。我们通过对金属（砷和铅）在地下水位和波动幅度可能发生的变化情况下的迁移进行水文地质-地球化学模型预测，研究了这一问题。我们使用了受污染土壤在温带气候区的观测初始条件和边界条件。结果表明，在未来 20 年内北欧浅层地下水系统平均水平可能适度上升（0.2m），这可能会使金属通过地下水的质量流增加 2-10 倍。在地下水水位波动幅度增加（季节性或事件性）的地区，也存在类似的金属迁移增加风险。在预测模型中忽略地下水动态，可能会导致金属迁移和未来变化的严重和系统低估。更一般地说，我们的研究结果表明，量化气候变化对金属迁移影响的关键是要了解未来地下水与高导水和地球化学异质的表土层之间的接触将如何变化。
