Chesapeake Bay nitrogen fluxes derived from a land-estuarine ocean biogeochemical modeling system: Model description, evaluation, and nitrogen budgets.
Chesapeake Bay nitrogen fluxes derived from a land-estuarine ocean biogeochemical modeling system: Model description, evaluation, and nitrogen budgets.
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DOI：
10.1002/2015jg002931
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发表时间：
2015-08
影响因子：
3.7
通讯作者：
Hood, Raleigh R.
中科院分区：
文献类型：
--
作者：
Feng, Yang;Friedrichs, Marjorie A. M.;Wilkin, John;Tian, Hanqin;Yang, Qichun;Hofmann, Eileen E.;Wiggert, Jerry D.;Hood, Raleigh R.
切萨皮克湾在将河流营养物质输出到邻近大陆架之前对其进行转化方面发挥着重要作用。虽然平均氮预算的切萨皮克湾以前已经估计从观测，年际变化的水文条件的不确定性仍然存在。在这项研究中，陆地-河口-海洋生物地球化学模拟系统的开发，量化切萨皮克河流氮输入，河口内的氮转化过程和氮的最终输出到沿海海洋。利用大量的原位和卫星数据对模型技术进行了评估，并利用2001-2005年的环境条件进行了模拟，以量化切萨皮克湾的氮收支。5年模拟的特点是大量的河流输入氮（154 × 109 g N yr−1），无机：有机组分之间的比例约为60：40。其中大部分在河口系统中被同化（34 × 109 g N yr−1）和掩埋（46 × 109 g N yr−1）。该海湾正的年净生态系统生产力进一步促成了大量有机氮向大陆架的平流输出（91 × 109 g N yr−1）和可忽略的无机氮输出。年际变化很强，特别是河流氮通量。在河流氮输入量高于平均水平的年份，大部分多余的氮（50-60%）作为有机氮从海湾输出，其余部分在埋藏，反硝化和无机输出到沿海海洋之间分配。在以前的模拟使用通用的陆架生态地球化学模型配方内的河口，河口生态地球化学模型在这里描述的产生更现实，更大的有机氮和更低的出口无机氮的货架。建立了切萨皮克湾的河口生态地球化学模型，计算了2001-2005年氮通量的年际变化。
The Chesapeake Bay plays an important role in transforming riverine nutrients before they are exported to the adjacent continental shelf. Although the mean nitrogen budget of the Chesapeake Bay has been previously estimated from observations, uncertainties associated with interannually varying hydrological conditions remain. In this study, a land‐estuarine‐ocean biogeochemical modeling system is developed to quantify Chesapeake riverine nitrogen inputs, within‐estuary nitrogen transformation processes and the ultimate export of nitrogen to the coastal ocean. Model skill was evaluated using extensive in situ and satellite‐derived data, and a simulation using environmental conditions for 2001–2005 was conducted to quantify the Chesapeake Bay nitrogen budget. The 5 year simulation was characterized by large riverine inputs of nitrogen (154 × 109 g N yr−1) split roughly 60:40 between inorganic:organic components. Much of this was denitrified (34 × 109 g N yr−1) and buried (46 × 109 g N yr−1) within the estuarine system. A positive net annual ecosystem production for the bay further contributed to a large advective export of organic nitrogen to the shelf (91 × 109 g N yr−1) and negligible inorganic nitrogen export. Interannual variability was strong, particularly for the riverine nitrogen fluxes. In years with higher than average riverine nitrogen inputs, most of this excess nitrogen (50–60%) was exported from the bay as organic nitrogen, with the remaining split between burial, denitrification, and inorganic export to the coastal ocean. In comparison to previous simulations using generic shelf biogeochemical model formulations inside the estuary, the estuarine biogeochemical model described here produced more realistic and significantly greater exports of organic nitrogen and lower exports of inorganic nitrogen to the shelf. A estuarine biogeochemical model was developed for Chesapeake Bay Interannually varying nitrogen fluxes were computed for 2001–2005 N export to the shelf was mostly organic, even when DIN input was high