Modeling Spatiotemporal Patterns of Ecosystem Metabolism and Organic Carbon Dynamics Affecting Hypoxia on the Louisiana Continental Shelf
Modeling Spatiotemporal Patterns of Ecosystem Metabolism and Organic Carbon Dynamics Affecting Hypoxia on the Louisiana Continental Shelf
复制标题
模拟影响路易斯安那大陆架缺氧的生态系统代谢和有机碳动态的时空模式
DOI：
10.1029/2019jc015630
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Gould, Jr., Richard W.
中科院分区：
文献类型：
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作者：
Jarvis, Brandon M.;Lehrter, John C.;Lowe, Lisa L.;Hagy, James D.;Wan, Yongshan;Murrell, Michael C.;Ko, Dong S.;Penta, Bradley;Gould, Jr., Richard W.
路易斯安那大陆架（LCS）上的缺氧区每年夏天形成，这是由于营养增强的初级生产和与密西西比/阿查法拉亚河流域（MARB）淡水排放相关的季节性分层。最近的实地研究已经确定，高产浅水近岸沃茨是整个大陆架碳生产的重要组成部分，有助于缺氧的形成。本研究应用了一个名为CGEM（沿海广义生态系统模型）的三维水动力-生物地球化学模型，以量化缺氧，碳生产，呼吸和运输的空间和时间模式，近岸和中间陆架地区之间的缺氧是最普遍的。我们首先证明，与实地观察相比，我们的模拟再现了碳生产，呼吸和底层水氧梯度的空间和时间模式。我们使用多年的模拟来量化运输的颗粒有机碳（POC）从近岸地区，河流有机物和浮游植物的碳生产最大。在我们的模拟中，碳生产和呼吸的空间位移是由向西和近海POC通量通过浮游植物的碳通量在表层和底层POC通量，支持异养呼吸的中间架经常观察到缺氧。这些结果支持现有的研究表明，海上碳通量缺氧形成的重要性，特别是在西部大陆架缺氧条件是最可变的。
The hypoxic zone on the Louisiana Continental Shelf (LCS) forms each summer due to nutrient‐enhanced primary production and seasonal stratification associated with freshwater discharges from the Mississippi/Atchafalaya River Basin (MARB). Recent field studies have identified highly productive shallow nearshore waters as an important component of shelf‐wide carbon production contributing to hypoxia formation. This study applied a three‐dimensional hydrodynamic‐biogeochemical model named CGEM (Coastal Generalized Ecosystem Model) to quantify the spatial and temporal patterns of hypoxia, carbon production, respiration, and transport between nearshore and middle shelf regions where hypoxia is most prevalent. We first demonstrate that our simulations reproduced spatial and temporal patterns of carbon production, respiration, and bottom‐water oxygen gradients compared to field observations. We used multiyear simulations to quantify transport of particulate organic carbon (POC) from nearshore areas where riverine organic matter and phytoplankton carbon production are greatest. The spatial displacement of carbon production and respiration in our simulations was created by westward and offshore POC flux via phytoplankton carbon flux in the surface layer and POC flux in the bottom layer, supporting heterotrophic respiration on the middle shelf where hypoxia is frequently observed. These results support existing studies suggesting the importance of offshore carbon flux to hypoxia formation, particularly on the west shelf where hypoxic conditions are most variable.