Global database of surface ocean particulate organic carbon export fluxes diagnosed from the 234Th technique

Through the processes of the biological pump, carbon is exported to the deep ocean in the form of dissolved and particulate organic matter. There are several ways by which downward export fluxes can be estimated. The great attraction of the 234Th technique is that its fundamental operation allows a downward flux rate to be determined from a single water column profile of thorium coupled to an estimate of POC/234Th ratio in sinking matter. We present a database of 723 estimates of organic carbon export from the surface ocean derived from the 234Th technique. Data were collected from tables in papers published between 1985 and 2013 only. We also present sampling dates, publication dates and sampling areas. Most of the open ocean Longhurst provinces are represented by several measurements. However, the Western Pacific, the Atlantic Arctic, South Pacific and the South Indian Ocean are not well represented. There is a variety of integration depths ranging from surface to 220m. Globally the fluxes ranged from -22 to 125 mmol of C/m**2/d. We believe that this database is important for providing new global estimate of the magnitude of the biological carbon pump.通过生物泵（biological pump）的作用过程，碳以溶解态有机质与颗粒态有机质的形式被输送至深海。目前存在多种估算海洋碳向下输出通量的方法。钍-234（²³⁴Th）技术的核心优势在于，其原理可通过单根水柱的钍剖面数据，结合沉降物质中颗粒有机碳/钍-234（POC/²³⁴Th）比值的估算值，直接求得向下输出速率。本研究构建了一套基于钍-234技术的表层海洋有机碳输出通量估算数据集，共计收录723组估算结果。数据仅采集自1985年至2013年间发表的学术论文表格。数据集同时包含采样日期、论文发表日期以及采样区域信息。多数开阔大洋朗赫斯特海区（Longhurst provinces）均有多组测量数据覆盖。但西太平洋、大西洋北极海域、南太平洋与南印度洋的采样数据相对不足。采样的积分深度跨度较大，范围从表层至220米不等。全球范围内的通量数值介于-22至125毫摩尔碳/（平方米·天）。我们认为，本数据集可为全球生物碳泵（biological carbon pump）的强度提供全新的估算支撑，具有重要的科研价值。