RAPID: Does dinitrogen fixation occur in oxygen minimum zones?

最近和多线的证据表明，二氮（N2）固定和反硝化作用可能是更紧密地耦合在空间比以前建议和nifH基因及其表达已被确定从内的最低含氧区（OMZ）的阿拉伯海。在该OMZ中，同位素证据和N2过饱和度表明N2固定是一个重要的过程。然而，尽管有关于阿拉伯海固氮的位置和程度的地球化学推断，以及该盆地通过反硝化作用从海洋中去除固定氮的重要性，但人们认为，有机MZ不包含固氮菌（固氮菌）。Old自治领大学的一组研究人员认为，OMZ可能是活跃的N2固定场所，在快速反应研究基金（RAPID）的资助下，他们将参加东热带北太平洋（ETNP）的机会巡航，以确定N2固定是否是OMZ内或附近的重要过程。他们希望能够更好地了解OMZ和主动反硝化区域的N2固定发生的位置。 在与船上其他海洋氮循环同事的合作中，他们希望能够同时比较反硝化和N2固定的速率，同时还可以检查ETNP OMZ内的生物多样性，群落结构以及微生物和N2固定生物的并置。武装与反硝化和固氮相对于OMZ的分布更全面的了解，一个更现实的观点内的N循环应该得到。更广泛的影响。结果将有助于目前的理解控制海洋固氮一般，以及N输入和OMZ的损失之间的平衡。 我们有理由认为，这个项目将改变我们对海洋氮循环的看法，特别是在氮输入方面。

Recent and multiple lines of evidence suggest that dinitrogen (N2) fixation and denitrification may be more closely coupled in space than previously suggested and nifH genes and their expression have been identified from within the oxygen minimum zone (OMZ) of the Arabian Sea. In this OMZ, isotopic evidence and N2 supersaturation suggests N2 fixation is a significant process. However, despite the geochemical inferences regarding the location and magnitude of N2 fixation in the Arabian Sea, and the importance of this basin in removing fixed N from the ocean via denitrification, it is thought that OMZs do not harbour diazotrophs (nitrogen fixing bacteria). A team of researchers at Old Dominion University believe that OMZs may be sites of active N2 fixation, and with funding from this Rapid Response Research Grant (RAPID) they will participate in a cruise of opportunity in the Eastern Tropical North Pacific (ETNP) to determine whether N2 fixation is an important process within or adjacent to this OMZ. They expect to achieve a better understanding of where N2 fixation occurs with respect to the OMZ and areas of active denitrification. In collaboration with other marine nitrogen cycle colleagues onboard, they expect to be able to simultaneously compare rates of denitrification and N2 fixation while also examining the diversity, community structure, and juxtaposition of denitrifying and N2 fixing organisms within the ETNP OMZ. Armed with this more comprehensive understanding of the distribution of denitrification and N2 fixation with respect to the OMZ, a more realistic view of the N cycle within should be gained. Broader Impacts. Results will contribute to current understanding of the controls on marine N2 fixation in general, as well as the balance between N inputs and losses from OMZs. IT is reasonable to think that this project will be transformative in shaping our view of the marine N cycle, particularly as regards to N inputs.