Temporal and Spatial Variations in Subterranean Estuary Geochemical Gradients and Nutrient Cycling Rates: Impacts on Groundwater Nutrient Export to Estuaries
Temporal and Spatial Variations in Subterranean Estuary Geochemical Gradients and Nutrient Cycling Rates: Impacts on Groundwater Nutrient Export to Estuaries
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DOI：
10.1029/2022jg007132
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发表时间：
2023-05
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影响因子：
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通讯作者：
Stephanie J. Wilson;I. Anderson;B. Song;C. Tobias
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文献类型：
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作者：
Stephanie J. Wilson;I. Anderson;B. Song;C. Tobias
地下河口（STEs）形成于地下水和海水混合的海陆边界。这些生物地球化学反应带在通过海底地下水排放（SGD）出口之前影响地下水携带的营养物质浓度和物种形成。我们检查了约克河河口（YRE）沿岸的一个STE，以确定SGD是否将溶解的无机氮（DIN）和磷（DIP）输送到上覆水域。我们评估了STE地球化学剖面在不同地点、时间和潮汐阶段的深度变化，估计了STE流动路径上的N去除，测量了水力梯度来估计SGD，并计算了潜在的营养通量。盐度、溶解氧（DO）、DIN和DIP随深度和季节变化显著（p为地下水DIN的100%）。SGD通量与弥漫性底栖生物通量在同一数量级，但在YRE河流平流输送的营养物质中所占比例<10%。我们的研究结果表明STE生物地球化学转化对SGD通量估算及其在海岸富营养化和营养动态中的作用的重要性。
Subterranean estuaries (STEs) form at the land‐sea boundary where groundwater and seawater mix. These biogeochemically reactive zones influence groundwater‐borne nutrient concentrations and speciation prior to export via submarine groundwater discharge (SGD). We examined a STE located along the York River Estuary (YRE) to determine if SGD delivers dissolved inorganic nitrogen (DIN) and phosphorus (DIP) to the overlying water. We assessed variations in STE geochemical profiles with depth across locations, times, and tidal stages, estimated N removal along the STE flow path, measured hydraulic gradients to estimate SGD, and calculated potential nutrient fluxes. Salinity, dissolved oxygen (DO), DIN, and DIP varied significantly with depth and season (p 100% of groundwater DIN. SGD fluxes were on the same order of magnitude as diffusive benthic fluxes but accounted for <10% of the nutrients delivered by fluvial advection in the YRE. Our results indicate the importance of STE biogeochemical transformations to SGD flux estimations and their role in coastal eutrophication and nutrient dynamics.