Where the past meets the present: connecting nitrogen from watersheds to streams through groundwater flowpaths
Where the past meets the present: connecting nitrogen from watersheds to streams through groundwater flowpaths
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过去与现在的交汇：通过地下水流道将氮气从流域连接到溪流
DOI：
10.1088/1748-9326/ad0c86
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发表时间：
2023
影响因子：
6.7
通讯作者：
Helton, Ashley M
中科院分区：
文献类型：
--
作者：
Moore, Eric M;Barclay, Janet R;Haynes, Adam B;Jackson, Kevin E;Bisson, Alaina M;Briggs, Martin A;Helton, Ashley M
向河流排放地下水是氮(N)的非点源，它混淆了N的缓解努力，并占流域年度N负荷的很大一部分。然而，我们缺乏对地下水N进入溪流和流域的位置和数量的了解。地下水流动路径末端的氮浓度是来自地下水补给的贡献陆地区域、含水层系统内以及地下水向河流排放的近流河岸区域的生物地球化学和物理过程的结果。我们的研究目标是量化混合土地利用流域地下水排放氮浓度的空间分布，并评估贡献和河岸土地覆盖、模拟含水层特征和地下水排放生物地球化学之间的关系如何解释地下水排放氮浓度的空间变化。我们通过集成高分辨率热红外测量来定位地下水排放、地下水的生物地球化学采样，以及将地下水排放地点与其贡献区域土地覆盖联系起来的颗粒跟踪模型，实现了这一点。流域内地下水排泄的地下水N负荷在河岸地下水排泄特征之间和内部有很大差异。地下水硝酸盐浓度在空间上具有不均一性，范围在0.03-11.45 mg-N/L以下，在几米范围内变化幅度可达20倍。结合颗粒示踪模型结果和土地覆盖指数，我们发现，地下水排放硝酸盐浓度最好的预测模型是线性混合效应模型，该模型解释了超过60%的硝酸盐浓度变化，包括含水层化学(溶解氧、Cl−、SO42−)、河岸地区森林覆盖和模拟的物理含水层特征(流量、欧氏距离)。我们的工作突出了混合土地利用流域内地下水排放硝酸盐浓度的显着空间变异性，以及了解地下水循环中许多时空尺度上的地下水N过程的必要性。
Groundwater discharge to streams is a nonpoint source of nitrogen (N) that confounds N mitigation efforts and represents a significant portion of the annual N loading to watersheds. However, we lack an understanding of where and how much groundwater N enters streams and watersheds. Nitrogen concentrations at the end of groundwater flowpaths are the culmination of biogeochemical and physical processes from the contributing land area where groundwater recharges, within the aquifer system, and in the near-stream riparian area where groundwater discharges to streams. Our research objectives were to quantify the spatial distribution of N concentrations at groundwater discharges throughout a mixed land-use watershed and to evaluate how relationships among contributing and riparian land cover, modeled aquifer characteristics, and groundwater discharge biogeochemistry explain the spatial variation in groundwater discharge N concentrations. We accomplished this by integrating high-resolution thermal infrared surveys to locate groundwater discharge, biogeochemical sampling of groundwater, and a particle tracking model that links groundwater discharge locations to their contributing area land cover. Groundwater N loading from groundwater discharges within the watershed varied substantially between and within streambank groundwater discharge features. Groundwater nitrate concentrations were spatially heterogeneous ranging from below 0.03–11.45 mg-N/L, varying up to 20-fold within meters. When combined with the particle tracking model results and land cover metrics, we found that groundwater discharge nitrate concentrations were best predicted by a linear mixed-effect model that explained over 60% of the variation in nitrate concentrations, including aquifer chemistry (dissolved oxygen, Cl−, SO 4 2−), riparian area forested land cover, and modeled physical aquifer characteristics (discharge, Euclidean distance). Our work highlights the significant spatial variability in groundwater discharge nitrate concentrations within mixed land-use watersheds and the need to understand groundwater N processing across the many spatiotemporal scales within groundwater cycling.
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影响因子：
3.2
作者：
A. Haynes;M. Briggs;E. Moore;Kevin Jackson;J. Knighton;D. Rey;A. Helton
通讯作者：
A. Haynes;M. Briggs;E. Moore;Kevin Jackson;J. Knighton;D. Rey;A. Helton
影响因子：
5.2
作者：
Byrnes, D. K.;Van Meter, K. J.;Basu, N. B.
通讯作者：
Basu, N. B.
冬季低流量条件下溪流中的硝酸盐作为遗留硝酸盐的指标
影响因子：
5.4
作者：
Henry M. Johnson;E. Stets
通讯作者：
E. Stets
影响因子：
5.4
作者：
C. Kennedy;D. Genereux;D. Corbett;H. Mitásová
通讯作者：
C. Kennedy;D. Genereux;D. Corbett;H. Mitásová
影响因子：
6.7
作者：
Chang, S. Y.;Zhang, Q.;Van Meter, K. J.
通讯作者：
Van Meter, K. J.