Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model
Variable C : N : P stoichiometry of dissolved organic matter cycling in the Community Earth System Model
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DOI：
10.5194/bg-12-209-2015
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发表时间：
2014-06
期刊：
影响因子：
4.9
通讯作者：
R. Letscher;J. K. Moore;Y. Teng;F. Primeau
中科院分区：
文献类型：
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作者：
R. Letscher;J. K. Moore;Y. Teng;F. Primeau
抽象的。溶解有机物 (DOM) 在海洋生物碳泵中发挥着重要作用，为约 20% 的出口产量提供平流/混合途径。众所周知，与颗粒有机物质库相比，DOM 的化学计量中氮 (N) 和磷 (P) 含量较低，这一事实在生物地球化学海洋大气环流模型中经常被忽略。然而，当量化上层海洋的碳输出并将 N 和 P 的养分循环与碳的养分循环联系起来时，DOM 的变量 C:N:P 化学计量变得很重要。在这里，我们利用 DOM 观测数据覆盖和离线示踪建模技术的最新进展，在简单的 DOM 循环生物地球化学海洋模型中客观地限制 DOM C:N:P 池的可变生产和再矿化率。然后将优化的 DOM 循环参数纳入社区地球系统模型 (CESM) 的生物地球化学元素循环 (BEC) 组件中，并根据海洋 DOM 观测数据的汇编进行验证。与使用规范 Redfield 比率的模拟相比，优化的 BEC 模拟（包括变量 DOM C:N:P 循环）可以更好地再现观察到的 DOM 空间梯度。研究发现，100 m 以下溶解有机 C、N 和 P 的全球年平均出口量为 2.28 Pg C yr−1（分别为 143 Tmol C yr−1、16.4 Tmol N yr−1、1 Tmol P yr−1），半不稳定（可降解）DOM 池的平均出口 C : N : P 化学计量为 225 : 19 : 1。溶解有机碳 (DOC) 输出占 100 m 以上深度有机碳输出总量的约 25%。
Abstract. Dissolved organic matter (DOM) plays an important role in the ocean's biological carbon pump by providing an advective/mixing pathway for ~ 20% of export production. DOM is known to have a stoichiometry depleted in nitrogen (N) and phosphorus (P) compared to the particulate organic matter pool, a fact that is often omitted from biogeochemical ocean general circulation models. However the variable C : N : P stoichiometry of DOM becomes important when quantifying carbon export from the upper ocean and linking the nutrient cycles of N and P with that of carbon. Here we utilize recent advances in DOM observational data coverage and offline tracer-modeling techniques to objectively constrain the variable production and remineralization rates of the DOM C : N : P pools in a simple biogeochemical-ocean model of DOM cycling. The optimized DOM cycling parameters are then incorporated within the Biogeochemical Elemental Cycling (BEC) component of the Community Earth System Model (CESM) and validated against the compilation of marine DOM observations. The optimized BEC simulation including variable DOM C : N : P cycling was found to better reproduce the observed DOM spatial gradients than simulations that used the canonical Redfield ratio. Global annual average export of dissolved organic C, N, and P below 100 m was found to be 2.28 Pg C yr−1 (143 Tmol C yr−1, 16.4 Tmol N yr−1, and 1 Tmol P yr−1, respectively, with an average export C : N : P stoichiometry of 225 : 19 : 1 for the semilabile (degradable) DOM pool. Dissolved organic carbon (DOC) export contributed ~ 25% of the combined organic C export to depths greater than 100 m.