Dominance of benthic flux of REEs on continental shelves: implications for oceanic budgets
Dominance of benthic flux of REEs on continental shelves: implications for oceanic budgets
复制标题
大陆架上稀土元素底栖通量的主导地位：对海洋预算的影响
DOI：
10.7185/geochemlet.2223
复制
发表时间：
2022-06-30
影响因子：
4.9
通讯作者：
Vance, D.
中科院分区：
文献类型：
--
作者：
Deng, K.;Yang, S.;Vance, D.
稀土元素是跟踪海洋生物地球化学过程的有力工具。然而，我们对稀土元素来源的认识是不完整的，导致对其海洋循环的解释存在争议。大陆边缘沉积物通常被认为是一个主要的来源，但了解控制潜在来源的过程所需的沉积物孔隙水数据很少。本文对长江口-东海陆架的孔隙水和河口REE数据进行了测量和整理。研究表明，稀土元素从浅层孔隙水向上覆海水的释放与锰的还原有关。相反，在深层孔隙水中，稀土元素可能通过自生含稀土相的形成而被去除。该沉积源可能解释中高盐度下河口稀土元素的添加。我们的计算表明，底栖生物通量是东海陆架最大的Nd源（约40%）。然而，在全球范围内，尽管平流主导的陆架上的底栖Nd通量较高，但更广泛的深海仍然主导着总面积综合底栖通量。我们的结果要求对底栖生物向海洋的稀土通量的大小进行更广泛的调查。
Rare earth elements (REEs) are powerful tools to track oceanic biogeochemical processes. However, our understanding of REE sources is incomplete, leading to contro-versial interpretations regarding their oceanic cycling. Continental margin sediments are often assumed to be a major source, but the sediment pore water data required to understand the processes controlling that potential source are scarce. Here, we mea-sure and compile pore water and estuarine REE data from the Changjiang (Yangtze) estuary – East China Sea shelf. We show that release of REEs, from shallow pore water to overlying seawater, is coupled to Mn reduction. In contrast, REEs are removed in deep pore water, perhaps via formation of an authigenic REE-bearing phase. This sedimentary source can potentially explain REE addition in the estuary at mid-high salinity. Our calculations suggest that the benthic flux is the largest Nd source ( ∼ 40 %) on the East China Sea shelf. Globally, however, despite a higher benthic Nd flux on the advection-dominated shelf, the much more extensive deep ocean still domi-nates the total area-integrated benthic flux. Our results call for a more extensive investigation of the magnitude of the benthic flux of REEs to the oceans.