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着产生和消耗气候活性气体（如二氧化碳、一氧化二氮和甲烷）的微生物过程。海洋酸化的气候依赖变化和地表下氧水平的降低预计会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度，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中的生化作用已经在少数个别物种中得到了很好的确立，并且在硅藻（生态上重要的浮游植物分类群）和反硝化菌中有一些关于铜代谢的信息，但对许多其他细菌和浮游植物群中铁和铜的生理知之甚少。此外，海洋微生物对气候相关的痕量金属可用性变化的响应在很大程度上尚未被探索。该提案寻求资金来研究海洋pH和O2水平的变化如何影响铁和铜的生物利用度，以及这些变化如何影响浮游植物以及反硝化和甲烷氧化细菌的关键自养和异养途径（如温室气体循环、微量金属运输、体内平衡）的速率。拟议的研究计划将结合实地研究和实验室研究。实地调查将在a)东北亚北极太平洋进行，这是一个铁贫乏的地区，表层海水酸化，地表下氧气最小带正在扩大，b)北冰洋，这是一个研究不足的地区，海洋酸化和甲烷释放突出。本研究将促进我们对关键海洋微生物微量金属生理的基础认识，并有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养分循环，对于更好地预测气候变化对海洋生物地球化学循环、碳固存能力和“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.