Effects of Geologic Setting on Contaminant Transport in Deltaic Aquifers
Effects of Geologic Setting on Contaminant Transport in Deltaic Aquifers
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DOI：
10.1029/2022wr031943
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发表时间：
2022-08
影响因子：
5.4
通讯作者：
Zhongyuan Xu;J. Hariharan;P. Passalacqua;E. Steel;A. Chadwick;C. Paola;A. Paldor;H. Michael
中科院分区：
文献类型：
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作者：
Zhongyuan Xu;J. Hariharan;P. Passalacqua;E. Steel;A. Chadwick;C. Paola;A. Paldor;H. Michael
沿海三角洲含水层容易因海水入侵、地质和人为污染以及抽取地下水而退化。污染物的分布和迁移高度依赖于地下沉积结构，例如优先引导流动的通道化特征的存在。地表沉积物会随着海平面上升（SLR）和沉积物供应而变化，但目前尚不清楚这些地表变化如何影响地下水溶质在含水层中的分布和迁移。在这里，我们探讨的影响，SLR和沉积物供应含水层的异质性和污染物输运的影响。我们使用基于过程的数值模型DeltaRCM生成的地下非均质性的实现，该模型模拟了具有不同输入砂分数和SLR速率的三角洲含水层的演变。我们模拟地下水流和溶质运移通过这些存款在三个污染的情况下：（a）在陆地表面的广泛污染的垂直运输，（B）从河水渗透的垂直运输，和（c）横向海水入侵。模拟结果表明，三角洲含水层海水入侵的脆弱性与砂的分数，而污染物的垂直运输，如广泛的浅层污染和河水渗透，受通道堆积模式。这种分析提供了新的见解之间的连接沉积系统的属性和脆弱性不同模式的地下水污染。它还说明了脆弱性如何可能在三角洲内局部变化，由于沉积的差异。结果表明，地下水管理策略可以通过考虑地表特征，三角洲内的位置，以及含水层沉积过程中的外部强迫来改善。
Coastal deltaic aquifers are vulnerable to degradation from seawater intrusion, geogenic and anthropogenic contamination, and groundwater abstraction. The distribution and transport of contaminants are highly dependent on the subsurface sedimentary architecture, such as the presence of channelized features that preferentially conduct flow. Surface deposition changes in response to sea‐level rise (SLR) and sediment supply, but it remains unclear how these surface changes affect the distribution and transport of groundwater solutes in aquifers. Here, we explore the influence of SLR and sediment supply on aquifer heterogeneity and resulting effects on contaminant transport. We use realizations of subsurface heterogeneity generated by a process‐based numerical model, DeltaRCM, which simulates the evolution of a deltaic aquifer with different input sand fractions and rates of SLR. We simulate groundwater flow and solute transport through these deposits in three contamination scenarios: (a) vertical transport from widespread contamination at the land surface, (b) vertical transport from river water infiltration, and (c) lateral seawater intrusion. The simulations show that the vulnerability of deltaic aquifers to seawater intrusion correlates to sand fraction, while vertical transport of contaminants, such as widespread shallow contamination and river water infiltration, is influenced by channel stacking patterns. This analysis provides new insights into the connection between the depositional system properties and vulnerability to different modes of groundwater contamination. It also illustrates how vulnerability may vary locally within a delta due to depositional differences. Results suggest that groundwater management strategies may be improved by considering surface features, location within the delta, and the external forcings during aquifer deposition.