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

缺氧区（ODZs）是全球海洋中溶解氧浓度非常低的区域。低氧浓度影响反硝化速率，这是一种将硝酸盐转化为氮气的微生物过程。这可能导致海洋中硝酸盐的大量流失。硝酸盐是海洋中支持海洋生态系统的重要营养物质。海洋变暖可能会扩大这些臭氧消耗物，因此我们必须了解臭氧消耗物在这些地区的化学和生物学中的作用。这种理解需要对营养物和氧气浓度随时间反复取样。研究人员计划利用现有拨款的可用船舶时间，在两年的时间内，分别在春季、夏季和冬季对东部热带北太平洋（ETNP） ODZ进行六次采样。其目的是确定东太平洋东部地区ODZ最近扩大的持久性和季节性，并查明造成任何观察到的变化的过程。这项研究将支持华盛顿大学的科学教师硕士项目，该项目为研究人员、研究生和小学青年提供了一个联系，并将为两名本科生提供资金，让他们参加R/V汤普森号的两次研究巡航。该项目旨在回答在ETNP的ODZ中观察到的反硝化速率增加是否仅仅是由于日益严重的缺氧问题，还是可以归因于采样时间和季节性。此外，将对硝酸盐损失的增加进行调查，以确定它是否真的是由于ODZ中反硝化速率的增加或其他原因。气候模型模拟预测海洋溶解氧含量会受到很大的扰动，这可能会产生比纯氧化学更深远的影响。这项研究希望回答这样一个问题：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，而反硝化作用反过来又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.