Quantifying the Ocean's Carbon Pumps with Dissolved Gas Measurements

海洋自然地从大气中去除二氧化碳，将其输送到深海，并将其储存在那里，导致大气水平较低，气候更温和。随着人类燃烧燃料并向大气中排放二氧化碳，我们需要了解海洋的天然碳运输机制是如何工作的，它们的工作速度有多快，以及它们是如何变化的，以便对未来的气候做出准确的预测，我们的社会可以利用这些预测来做出决策。我的研究旨在揭示和量化这些机制使用新的测量溶解气体。我们的研究小组已经开发出高精度测量溶解惰性气体浓度（氖、氩、氪和氙）的方法。这些气体没有生物功能，只对海洋中的物理过程有反应。我们将使用稀有气体测量来量化影响海洋中所有气体的物理过程的速率，例如空气-海洋气体交换和温度驱动的溶解度变化。这些过程控制着稠密海水沉入深海时携带的碳量。通过与大型气候建模者的直接合作，我们将改进这些过程在气候预测模型中的表现方式。我们的研究还侧重于生物过程，特别是光合作用产生的有机碳从海洋表面下沉，这是一个重要但量化不足的碳运输机制。我们已经开发出一种方法，通过对溶解气体的氧/氩比的高精度测量，来量化这种从表面“输出”的速率。现在，我们将扩展我们的技术，通过传感器来量化碳排放量，这些传感器可以检测海洋浮子和滑翔机上的氧气浓度，这些浮子和滑翔机可以在水柱中自主上下移动。这项工作将扩大作出这些估计的空间和时间尺度。我们的总体目标之一是建立一个基线，以检测海洋生产力的未来变化。任何变化不仅会影响海洋对大气中二氧化碳的吸收，还会影响海洋生态系统和依赖它的渔业。我们的第三个研究重点是从海洋中剥离生物可利用氮的反应，植物需要氮进行光合作用。这些被称为反硝化的反应发生在海洋中没有氧气的区域。这些缺氧区正在扩大，这意味着反硝化可能会影响未来全球海洋生物生产力的速度。我们已经开发出了检测这种反应的方法，使用高精度测量溶解在海洋中的N2气体。我们将在当地的萨尼奇湾（Saanich Inlet）和北冰洋（Arctic Ocean）对反硝化进行量化，前者为研究缺氧区提供了一个方便的天然实验室，而后者对反硝化反应的量化程度最低。

The ocean naturally removes carbon dioxide from the atmosphere, transports it to the deep, and stores it there, resulting in lower atmospheric levels and a more moderate climate. As humans burn fuels and add carbon dioxide to the atmosphere, we need to understand how the ocean's natural carbon transport mechanisms work, how fast they work, and how they are changing in order to make accurate projections of future climate that our society can use to make decisions. My research seeks to uncover and quantify these mechanisms using novel measurements of dissolved gases.Our research group has developed methods to make high precision measurements of dissolved noble gas concentrations (neon, argon, krypton, and xenon). These gases have no biological function, responding only to physical processes in the ocean. We will use our noble gas measurements to quantify the rates of physical processes that impact all gases in the ocean, such as air-sea gas exchange and temperature-driven solubility changes. These processes control how much carbon is carried as dense waters sink into the deep sea. Through direct collaborations with large-scale climate modellers, we will improve the way these processes are represented in the models from which climate projections are made.Our research also focuses on biological processes, particularly the sinking of organic carbon created by photosynthesis out of the surface ocean, an important but poorly quantified carbon transport mechanism. We have developed ways of quantifying this “export” rate from the surface using high precision measurements of the oxygen/argon ratio of dissolved gases. We will now expand our techniques to quantify carbon export from sensors that detect oxygen concentrations on ocean floats and gliders that autonomously move up and down through the water column. This work will expand the space and time scales over which these estimates are made. One of our overall goals is to establish a baseline against which future changes in ocean productivity can be detected. Any changes could affect not only ocean uptake of atmospheric carbon dioxide but also the ocean ecosystem and fisheries that rely on it.Our third research focus is on reactions that strip bioavailable nitrogen, which plants need to photosynthesize, out of the ocean. These reactions, known as denitrification, take place in regions of the ocean with no oxygen. These oxygen deficient zones are expanding, which means that denitrification could affect global rates of ocean biological productivity in the future. We have developed methods to detect this reaction using high precision measurements of N2 gas dissolved in the ocean. We will quantify denitrification both in local Saanich Inlet, which provides an accessible natural laboratory to study oxygen deficient zones, and in the Arctic Ocean, where these reactions are least well quantified.