Metrics that matter for assessing the ocean biological carbon pump
Metrics that matter for assessing the ocean biological carbon pump
复制标题
DOI：
10.1073/pnas.1918114117
复制
发表时间：
2020-05-05
影响因子：
11.1
通讯作者：
Siegel, David A.
中科院分区：
文献类型：
--
作者：
Buesseler, Ken O.;Boyd, Philip W.;Siegel, David A.
生物碳泵（BCP）包括广泛的过程，这些过程决定了海洋内部的碳供应、消耗和储存。越来越明显的是，BCP效率的微小变化可以显著改变海洋碳固存，从而改变大气CO2和气候，以及中层水生态系统的功能。地球系统模型，包括联合国政府间气候变化专门委员会使用的模型，通常评估在固定参考深度进入海洋内部的POC（颗粒有机碳）通量。将这些通量外推到其他深度，定义BCP效率，通常使用理想化和基于经验的通量-vs.深度关系，通常被称为“马丁曲线”。“我们使用了一个新的海洋上层POC通量汇编，揭示了BCP效率的不同模式，这取决于通量是在固定的参考深度还是相对于阳光照射的真光层（Ez）的深度进行评估。我们发现，固定深度的方法低估了BCP的效率时，Ez是浅的，反之亦然。这一调整改变了对BCP效率的区域评估以及全球碳预算和对先前BCP研究的解释。随着最近几项国际研究正在进行中，以研究海洋BCP，有新的和独特的机会，以提高我们对BCP效率的机械控制的理解。然而，如果我们使用一组常见的基于Ez-based指标，我们将只能比较研究之间的结果。
The biological carbon pump (BCP) comprises wide-ranging processes that set carbon supply, consumption, and storage in the oceans' interior. It is becoming increasingly evident that small changes in the efficiency of the BCP can significantly alter ocean carbon sequestration and, thus, atmospheric CO2 and climate, as well as the functioning of midwater ecosystems. Earth system models, including those used by the United Nation's Intergovernmental Panel on Climate Change, most often assess POC (particulate organic carbon) flux into the ocean interior at a fixed reference depth. The extrapolation of these fluxes to other depths, which defines the BCP efficiencies, is often executed using an idealized and empirically based flux-vs.-depth relationship, often referred to as the "Martin curve." We use a new compilation of POC fluxes in the upper ocean to reveal very different patterns in BCP efficiencies depending upon whether the fluxes are assessed at a fixed reference depth or relative to the depth of the sunlit euphotic zone (Ez). We find that the fixed-depth approach underestimates BCP efficiencies when the Ez is shallow, and vice versa. This adjustment alters regional assessments of BCP efficiencies as well as global carbon budgets and the interpretation of prior BCP studies. With several international studies recently underway to study the ocean BCP, there are new and unique opportunities to improve our understanding of the mechanistic controls on BCP efficiencies. However, we will only be able to compare results between studies if we use a common set of Ez-based metrics.