Nitrate Removal Within Heterogeneous Riparian Aquifers Under Tidal Influence
Nitrate Removal Within Heterogeneous Riparian Aquifers Under Tidal Influence
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DOI：
10.1029/2019gl085699
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发表时间：
2020-05
影响因子：
5.2
通讯作者：
C. Wallace;A. Sawyer;M. Soltanian;R. Barnes
中科院分区：
文献类型：
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作者：
C. Wallace;A. Sawyer;M. Soltanian;R. Barnes
沿海河流中的潮汐驱动河流-地下水(地下)交换，并提供去除硝酸盐的机会，这可能会改善沿海水质。滨海漫滩沉积物中的粉砂层可以改变硝酸盐的流动和转化。我们的目标是了解沉积物的非均质性如何影响感潮河流附近的氮素动态。数值模拟表明，含氧、变饱和砂层和缺氧、富含有机质的粉砂层分别是硝化和反硝化的场所。随着砂透镜变得更长和更紧密，河水和硝酸盐通过非均质沉积物的交换随着含砂率的增加而增加。从河水中去除的硝酸盐的量也增加了，但在通过潜流带的总硝酸盐交换中所占的比例较小，导致去除效率下降。我们的结果表明，对含水层非均质性的准确描述有助于更好地理解泛滥平原沉积物中养分转化的位置。
Tides in coastal rivers drive river‐groundwater (hyporheic) exchange and provide opportunities for nitrate removal that may improve coastal water quality. Silt and sand layers in coastal floodplain sediments can alter the flow and transformation of nitrate. Our goal was to understand how sediment heterogeneity influences nitrogen dynamics near tidal rivers. Numerical simulations show that oxic, variably saturated sand layers and anoxic, organic‐rich silt layers are sites of nitrification and denitrification, respectively. The exchange of river water and nitrate through heterogeneous sediments increases with sand fraction, as sand lenses become longer and more connected. The amount of nitrate removed from river water also increases but represents a smaller portion of total nitrate exchange through the hyporheic zone, causing removal efficiency to decline. Our results suggest that accurate characterization of aquifer heterogeneity leads to an improved understanding of sites of nutrient transformation within floodplain sediments.