Cycling of Vitamin B12 in the Ocean

摘要-035199尽管已知超过65种浮游植物是维生素B12营养缺陷型的，这意味着它们需要外源供应才能生长，但海洋中初级生产的有机调节还没有得到很好的理解。 虽然在过去10年中进行了重大的研究努力，以了解微量金属和其他无机微量营养素对浮游植物生产的重要性，但维生素B12等有机生长因子的作用却被忽视了。 对维生素B12在海洋环境中的循环缺乏明确的了解，也妨碍了对甲烷的产生、有机螯合剂的形成（这可能控制钴等某些生物活性微量金属的生物利用率）以及在世界海洋某些区域观察到的浮游植物组合变化（从需要维生素的物种到不需要维生素的物种）的了解。不幸的是，缺乏快速可靠的定量B12技术，阻碍了海洋环境中维生素B12研究的进展。 在这项研究中，纽约州立大学斯托尼布鲁克分校的研究人员开发了一种新的方法，通过固相萃取预浓缩，反相HPLC梯度洗脱定量，紫外-可见吸收检测，直接测定海水中的维生素B12。 通过使用这项新技术，研究人员将研究维生素B12在不同海洋地球化学区的海洋循环。 需要这些信息来评估这种维生素在海洋环境中的重要性，以及验证以前使用生物测定技术进行的研究。 选择实地研究地点是为了提供关于维生素B12在各种海洋环境（南大洋、马尾藻海、中部和下加利福尼亚的上升流区域、Cariaco盆地和沿海环境）中循环的最大信息量。 这些B12测量值将使用一套分析来解释，以确定被采样的水中的主要浮游植物群体，以及DOC，POC，PON，叶绿素a，无机营养素和细菌生物量的分析。 确定B12在对比海洋学制度中的循环不仅将更好地了解影响“生物泵”的过程，而且还将更好地了解世界海洋中的甲烷。 因此，这种新的维生素B12方法的应用有可能在进一步了解如何提高海洋的碳封存能力方面发挥至关重要的作用。

ABSTRACTOCE-035199 The organic regulation of primary production in the ocean is not well understood, despite the fact that more than 65 species of phytoplankton are known to be auxotrophic for vitamin B12, meaning they require exogenous supplies for growth. While a major research effort has been directed in the last 10 years to understand the importance of trace metals and other inorganic micronutrients on phytoplankton production, the role of organic growth factors such vitamin B12 has been overlooked. The lack of clear understanding of the cycling of vitamin B12 in the marine environment has also hindered the understanding of methane production, the formation of organic chelators (which may control the bioavailability of some bioactive trace metals such as cobalt), and phytoplankton assemblage shifts (from vitamin-requiring to non-vitamin-requiring species) observed in some regions of the world ocean. Unfortunately, the lack of availability for a quantifying B12 in a quick and reliable technique has hindered the progress of vitamin B12 studies in the marine environment. In this study, researchers at SUNY at Stony Brook have developed a new method for the direct determination of vitamin B12 in seawater by pre-concentration using solid phase extraction, quantification using reversed phase HPLC with gradient elution, and detection by UV-visible absorption. By using this new technique the researchers will study the marine cycling of vitamin B12 in various biogeochemical provinces. This information is needed to evaluate the importance of this vitamin in the marine environment, as well as to validate previous studies carried out using the bioassay technique. The field study sites have been selected to give the maximum amount of information about the cycling of vitamin B12 in a broad range of marine environments (Southern Ocean, Sargasso Sea, upwelling regions of central and Baja California, the Cariaco Basin and a coastal environment). These B12 measurements will be interpreted using a suite of analyses to determine the dominant phytoplankton groups in the water being sampled, as well as analyses of DOC, POC, PON, chlorophyll a, inorganic nutrients and bacterial biomass. The determination of B12 cycling in contrasting oceanographic regimes will not only provide a better understanding of the processes influencing the "biological pump" but also of methane in the world ocean. Therefore, the application of this new vitamin B12 method has the potential to play a vital role in furthering our understanding of how the carbon sequestration capacity of the ocean could be enhanced.