Assessing the impact of global change on the distribution and physicochemical speciation of bioactive trace elements in seawater

必需微量元素的分布和生物可利用性可影响海洋生产力、生态系统结构和温室气体的海气交换。因此，要了解海洋生物地球化学循环对全球变化的响应，就必须研究微量元素的源、汇和化学形态。 这是因为海洋微生物对微量元素营养素有绝对的需求，这有助于解释微生物群落结构的时空变化，并设定海洋中碳和氮固定的上限。微量元素营养物对海洋微生物的生物利用率不仅受浓度控制，而且受必需元素在海水中的形态或化学形式控制。反过来，微生物可以通过生物介导的吸收/渗出、氧化还原反应和产生强有机配体来影响微量元素的分布和形态，所述强有机配体络合水柱中溶解的微量元素。拟议的研究计划将调查水文学和海洋酸化的变化将如何影响海洋表层沃茨中微量元素营养素的生物利用度，并继续研究控制海洋微生物与沿海和开放海洋环境中微量金属之间相互作用的主导机制。该计划的长期目标是了解海洋微生物生物活性微量金属的分布和可用性变化如何影响：1）C和N流入和流出海洋表面的量，以及2）颗粒物下沉通量的元素和同位素组成海洋内部。

The distribution and bioavailability of essential trace elements can impact marine productivity, ecosystem structure and air-sea exchange of greenhouse gases. An understanding of the response of marine biogeochemical cycles to global change must, therefore, include studies of trace element sources, sinks, and chemical speciation. This is because marine microbes have absolute requirements for trace element nutrients that can help explain temporal-spatial variability in microbial community structure and set upper limits on carbon and nitrogen fixation in the sea. The bioavailability of trace element nutrients to marine microbes is controlled not only by the concentration but the speciation, or chemical form, that essential elements take in seawater. In turn, microorganisms can affect the distribution and speciation of trace elements through biologically mediated uptake/exudation, redox reactions and the production of strong organic ligands that complex dissolved trace elements in the water column. The proposed research program will investigate how changing hydrography and ocean acidification will affect the bioavailability of trace element nutrients in marine surface waters and continue studies of the dominant mechanisms that control interactions between marine microbes and trace metals in coastal and open ocean environments. The long term goals of the program are to provide an understanding of how changes in the distribution and availability of bioactive trace metals to marine microbes affect: 1) the magnitude of C and N fluxes into and out of the surface ocean, and, 2) the elemental and isotopic composition of the sinking flux of particulate matter to the ocean interior.