Trace metal regulation of autotrophic and heterotrophic processes involved in the cycling of climate-active gases in the Subarctic Pacific and the Arctic Oceans

在世界上的大部分海洋中，铁（Fe）和铜（Cu）等“生物活性”微量金属的供应影响了产生和消耗气候活性气体（例如二氧化碳，一氧化二氮和甲烷）的微生物过程。海洋酸化和次表层氧含量下降的气候变化预计将最显著地改变铁和铜的化学性质，从而可能影响微生物气体循环的速率，导致生物地球化学气候反馈。虽然铁在光合作用和异养代谢的生化作用，以及建立在少数个别物种，和一些信息是可利用的铜代谢硅藻（一个生态上重要的浮游植物类群）和藻类，很少有人知道的生理铁和铜在许多其他细菌和浮游植物群体。此外，海洋微生物对与气候有关的微量金属可用性变化的反应在很大程度上还未得到探索。该提案寻求资金来研究海洋pH值和O2水平的变化将如何影响Fe和Cu的生物利用度，以及这些变化将如何影响关键的自养和异养途径（例如温室气体循环、微量金属运输、体内平衡）的速率浮游植物以及反硝化和甲烷氧化细菌。拟议的研究计划将整合实地和实验室研究。实地调查将在a）东北亚北极太平洋，一个铁贫乏区域，具有酸化的表层沃茨和不断扩大的次表层氧气最小区，以及B）北冰洋，一个未充分研究的区域，海洋酸化和甲烷释放突出。拟议的研究将推进我们对关键海洋微生物中痕量金属生理学的基础知识，并可能应用于环境生物修复。更广泛地说，了解微量元素如何控制北极和东北太平洋的碳和营养循环，对于更好地预测气候变化对海洋生物地球化学循环，碳封存能力和“气候活性”气体的海-气梯度的影响至关重要。

Over much of the world's oceans, the supply of 'bioactive' trace metals such as iron (Fe) and copper (Cu) influences microbial processes that produce and consume climate-active gases (e.g. carbon dioxide, nitrous oxide and methane). Climate-dependent changes in ocean acidification and decreasing sub-surface oxygen levels are expected to alter Fe and Cu chemistry most dramatically, thus potentially affecting the rate of microbial gas cycling, leading to biogeochemical climate feedbacks. Although the biochemical roles of Fe in photosynthetic and heterotrophic metabolism are well established in a few individual species, and some information is available on Cu metabolism in diatoms (an ecologically important phytoplankton taxon) and denitrifiers, little is known about the physiology of Fe and Cu in many other bacteria and phytoplankton groups. Moreover, the response of marine microorganisms to climate related changes in trace metal availability is largely unexplored. This proposal seeks funds to investigate how altered oceanic pH and O2 levels will affect Fe and Cu bioavailability, and how these changes will influence the rate of key autotrophic and heterotrophic pathways (e.g. greenhouse gas cycling, trace metal transport, homeostasis,) by phytoplankton, as well as denitrifying and methane oxidizing bacteria. The proposed research program will integrate field-based and laboratory studies. Field investigations will be conducted in a) the NE Subarctic Pacific, a Fe poor region with acidified surface waters and an expanding sub-surface oxygen minimum zone, and b) the Arctic Ocean, an understudied region where ocean acidification and methane release are prominent. The proposed research will advance our fundamental knowledge of trace metal physiology in key marine microorganisms, with possible applications for environmental bioremediation. More broadly, understanding how trace elements control C and nutrient cycling in the Arctic and NE Pacific Oceans is essential to better predict climate change impacts on marine biogeochemical cycles, C sequestration capacity and sea-air gradients of 'climate active' gases.