Magnitude, Variability and Controls of Particulate Export in the Upper Ocean

利用现有的和相关的全球海洋通量联合研究的国际数据集，伍兹霍尔海洋研究所的研究人员将研究出口和生产之间的关系，以及食物网过程在控制上层海洋出口中可能发挥的特殊作用。到目前为止的结果表明，碳固定和碳去除通过下沉颗粒的相对速率变化很大，作为当地食物网动态的函数。鉴于大量研究现在使用铀-238系列放射性同位素234 Th作为POC输出的代理，这些研究人员打算编制上层海洋颗粒有机碳输出的全球地图。他们将直接查看234 Th输出数据的全部范围，以评估季节性、偶发性或区域性通量变化与一系列物理和生物参数之间的趋势。 由于很大一部分输出可能发生在短脉冲或事件期间，因此，目标是帮助解释输出的可变性，以便更好地模拟更大时间或空间尺度上的长期平均输出，如果能够找到生产和输出变化的共同机制，则可以将其纳入更可靠的全球碳循环模型。虽然大部分海洋的特点是相对较低的POC输出，高输出的网站往往是以大型浮游植物，特别是硅藻为主的食物网的特点。如果这一结果成立，试图从表面叶绿素或生产预测新的和出口生产的模型将无法解决当地的碳平衡或允许一个模型的出口控制。对潜在输出过程的机械理解对于能够将这种理解纳入模型至关重要，特别是如果我们希望预测未来气候状态的通量。

ABSTRACTOCE-0097232Using existing and related international data sets from the Joint Global Ocean Flux Study, researchers at the Woods Hole Oceanographic Institution will study the relationships between export and production and the special role that food web processes may have in controlling upper ocean export. The results thus far indicate that the relative rates of carbon fixation and carbon removal via sinking particles vary widely as a function of local food web dynamics. Given the large number of studies that now use the uranium-238 series radioisotope 234Th as a proxy for POC export, these investigators intend to compile global maps of particulate organic carbon export from the upper ocean. They will look directly at the full range of 234Th export data to assess trends between seasonal, episodic, or regional flux variability and a suite of physical and biological parameters. Because a significant portion of export may occur during short pulses or events, the goal is to help explain export variability in order to better model long-term mean export over larger time or space scales.If common mechanisms can be found for the variations of production and export, these could then be incorporated into more reliable models of the global carbon cycle. While much of the ocean is characterized by low relative POC export, sites of high export are most often characterized by food webs dominated by large phytoplankton, in particular diatoms. If this result holds, models that attempt to predict new and export production from surface chlorophyll or production alone will not resolve the local carbon balance or allow one to model export controls. A mechanistic understanding of the underlying export processes is crucial to being able to incorporate this understanding into models, particularly if we desire to predict fluxes in future climate states.