부산대학교 도서관

The ocean's biological carbon pump (BCP) plays a major role in the global carbon cycle. A fraction of the photosynthetically fixed organic carbon produced in surface waters is exported below the sunlit layer as settling particles (e.g., marine snow). Since the seminal works on the BCP, global estimates of the global strength of the BCP have improved but large uncertainties remain (from 5 to 20 Gt C yr.sup.-1 exported below the euphotic zone or mixed-layer depth). The .sup.234 Th technique is widely used to measure the downward export of particulate organic carbon (POC). This technique has the advantage of allowing a downward flux to be determined by integrating the deficit of .sup.234 Th in the upper water column and coupling it to the POC/.sup.234 Th ratio in sinking particles. However, the factors controlling the regional, temporal, and depth variations of POC/.sup.234 Th ratios are poorly understood. We present a database of 9318 measurements of the POC/.sup.234 Th ratio in the ocean, from the surface down to 5500 m, sampled on three size fractions (â¼0.7 µm, â¼1-50 µm, â¼50 µm), collected with in situ pumps and bottles, and also from bulk particles collected with sediment traps. The dataset is archived in the data repository PANGAEA.sup.® under https://doi.org/10.1594/PANGAEA.911424 (Puigcorbé, 2019). The samples presented in this dataset were collected between 1989 and 2018, and the data have been obtained from published papers and open datasets available online. Unpublished data have also been included. Multiple measurements can be found in most of the open ocean provinces. However, there is an uneven distribution of the data, with some areas highly sampled (e.g., China Sea, Bermuda Atlantic Time Series station) compared to some others that are not well represented, such as the southeastern Atlantic, the south Pacific, and the south Indian oceans. Some coastal areas, although in a much smaller number, are also included in this global compilation. Globally, based on different depth horizons and climate zones, the median POC/.sup.234 Th ratios have a wide range, from 0.6 to 18 µmol dpm.sup.-1.
Byline: Viena Puigcorbé, Pere Masqué, Frédéric A. C. Le Moigne To access, purchase, authenticate, or subscribe to the full-text of this article, please visit this link: https://essd.copernicus.org/articles/12/1267/2020/essd-12-1267-2020.html, or to download [...]