Permanence of the recent expansions of the OMZ and denitrification regimes in the eastern tropical North Pacific

缺氧区(ODZ)是全球海洋中海水中溶解氧浓度非常低的区域。低氧浓度会影响反硝化的速度，反硝化是一种将硝酸盐转化为氮气的微生物过程。这可能会导致海洋中硝酸盐的大量损失。硝酸盐是海洋中一种重要的营养物质，支持海洋生态系统。海洋变暖可能会扩大这些臭氧专用区，因此我们必须了解臭氧专用区对这些地区的化学和生物的作用。这种理解需要随着时间的推移对营养和氧气浓度进行反复采样。调查员计划利用现有赠款中的可用船舶时间，在春季、夏季和冬季的两年时间里，对东热带北太平洋(ETNP)ODZ进行六次采样。其目的是确定ETNP中ODZ最近扩大的永久性和季节性，以及确定对任何观察到的变化负责的过程。这项研究将支持华盛顿大学的科学教师科学硕士计划，该计划在研究人员、研究生和小学青年之间提供联系，并将为两名本科生提供资金，让他们参加R/V Thompson上的两次研究巡航。该项目试图回答ETNP ODZ中观察到的反硝化率增加是仅仅由于日益严重的缺氧问题，还是可以归因于样品的时机和季节性。此外，将对硝酸盐损失的增加进行调查，以得出结论：这是否真的是由于ODZ的反硝化速率增加或其他原因造成的。气候模型模拟预测，海洋的溶解氧含量将受到很大的扰动，这可能会产生比纯粹的氧化学更严重的后果。这项研究希望回答这样一个问题，即气候变化对溶解氧的影响将如何影响海洋中的反硝化作用，而反硝化作用又会对限制海洋生产力产生更大的影响。

Oxygen Deficient Zones (ODZs) are regions in the global ocean where concentrations of dissolved oxygen in seawater are very low. Low oxygen concentrations affect rates of denitrification, a microbial process in which nitrate is converted to nitrogen gas. This can lead to significant losses of nitrate from the ocean. Nitrate is an important nutrient in the ocean that supports ocean ecosystems. Ocean warming is likely to expand these ODZs making it imperative we understand the role of the ODZs on the chemistry and biology of these regions. This understanding requires repeated sampling of nutrient and oxygen concentrations through time. The investigator plans to utilize available ship time from an existing grant to sample the Eastern Tropical North Pacific (ETNP) ODZ six times over a two year period during the spring, summer, and winter months. The aim is to determine the permanence and seasonality of the recent expansion of the ODZ in the ETNP, as well as identify the processes responsible for any observed changes. This research will support the University of Washington's Masters in Science for Science Teachers program, which provides a link between researchers, graduate students, and elementary aged youth, and there will be funds provided for two undergraduate students to participate in two research cruises on the R/V Thompson.This project seeks to answer whether observed increased rates of denitrification in the ODZ of the ETNP are solely due to a growing oxygen deficiency problem or can be attributed to sample timing and seasonality. Additionally, the increased loss of nitrate will be investigated to conclude whether it really is due to increased rates of denitrification in the ODZ or some other cause. Climate model simulations predict a large perturbation to the dissolved oxygen content of the ocean, which could have further consequences than purely oxygen chemistry. This study hopes to answer the question of how climate change impacts on dissolved oxygen will affect denitrification in the ocean, which in turn has a much larger effect on limiting marine productivity.