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Development of a New Sediment Flux Model - Application in Chesapeake Bay
Progress in Oceanography ( IF 4.1 ) Pub Date : 2020-06-01 , DOI: 10.1016/j.pocean.2020.102332
Zhengui Wang , Fei Chai , Damian Brady

Abstract Sediment biogeochemical processes impact pelagic ecosystems when the sediment receives particulate organic matter (POM) deposited from the water column above, consumes dissolved oxygen, and returns inorganic nutrients to the bottom water. However, an easy-to-apply sediment model is still lacking for pelagic biogeochemical modeling. In this study, we proposed a mass conservative, process-based and easy-to-apply sediment flux model (SFM) that endeavors to simplify Di Toro (2001)’s sediment flux model (DSFM) while maintaining the ability to model sediment fluxes in multiple environments (e.g., anoxic, normoxic, variable salinity, high and low organic matter deposition, etc.). It adopts a vertically integrated approach, and has a relatively simple structure with limited number of parameters. The mineralization scheme for POM is based on bacterial growth, which can resolve the diagenesis processes on different timescales. The inhibition effects of oxygen on denitrification of NO3 and desorption of PO4 are modeled using exponential functions. This new SFM is then implemented in the Chesapeake Bay to simulate sediment oxygen demand (SOD) and sediment NH4/NO3/PO4/Silica fluxes across the sediment–water interface. To estimate POM depositional fluxes from the water column, a new method is introduced that links surficial sediment and bottom-water POM concentrations. Further integration of this method into the SFM turns the model calibration into a mass conservative and self-consistent process, which is well constrained by observations. The modeled sediment fluxes from the new SFM match observations across seasons and stations with correlation coefficient ranging from 0.3 to 0.7. The successful application of SFM in Chesapeake Bay and subsequent analysis show that the new SFM has many advantages including mass conservation, high temporal resolution, relatively simple structure, and easy implementation. The SFM is a good tool for linking pelagic ecosystem models to sediment biogeochemical processes.

中文翻译:

一种新的沉积物通量模型的开发——在切萨皮克湾的应用

摘要 当沉积物接收从上方水柱沉积的颗粒有机物(POM),消耗溶解氧并将无机养分返回到底层水中时,沉积物生物地球化学过程会影响远洋生态系统。然而,对于远洋生物地球化学建模,仍然缺乏易于应用的沉积物模型。在这项研究中,我们提出了一个质量保守、基于过程且易于应用的沉积物通量模型 (SFM),它努力简化 Di Toro (2001) 的沉积物通量模型 (DSFM),同时保持模拟沉积物通量的能力在多种环境中(例如,缺氧、常氧、可变盐度、高低有机物沉积等)。它采用垂直整合的方式,结构相对简单,参数数量有限。POM 的矿化方案基于细菌生长,可以解决不同时间尺度上的成岩过程。氧气对 NO3 反硝化和 PO4 解吸的抑制作用使用指数函数建模。然后在切萨皮克湾实施这种新的 SFM 来模拟沉积物需氧量 (SOD) 和沉积物 - 水界面上的沉积物 NH4/NO3/PO4/二氧化硅通量。为了估计来自水体的 POM 沉积通量,引入了一种将表层沉积物和底水 POM 浓度联系起来的新方法。将该方法进一步集成到 SFM 中,将模型校准变成了一个质量保守和自洽的过程,这很好地受观测约束。来自新 SFM 的模拟沉积物通量与跨季节和站点的观测相匹配,相关系数从 0.3 到 0.7。SFM 在切萨皮克湾的成功应用和后续分析表明,新的 SFM 具有质量守恒、时间分辨率高、结构相对简单、易于实现等诸多优点。SFM 是将远洋生态系统模型与沉积物生物地球化学过程联系起来的好工具。
更新日期:2020-06-01
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