Photochemical Oxygen Consumption in Marine Waters

氧化海洋光化学反应是修改和重新矿化陆源DOM的重要步骤，如个别例子和间接机制证据所示。重要的海洋来源的DOM可能也进入了这个周期。该项目将通过(1)在灵敏度允许的情况下直接进行O2吸收测量，以及(2)使用对“蓝水”和低反应性沿海水研究足够灵敏的间接方法，将总的光氧化过程量化为耗氧量。这一结果将为光氧化在海洋碳氧循环中的作用提供亟需的定量评估。与DOM氧化密切相关的耗氧量将在沿海和河口水域以及疏水吸附浓缩的有机物中进行测量。直接吸氧量将使用具有自动数据采集功能的脉冲极谱电极进行测量。一种灵敏的新间接技术，根据经验与直接测量进行了校准，将量化“蓝色”和低活动沿海水域中主要耗氧物种的通量。我们将研究波长、光强、温度、氧气浓度和长时间光解等变量对O2消耗速率的影响，以了解它们的(生物)地球化学意义，并确定O2吸收/C再矿化的主要机制。

Oxidative marine photochemical reactions are an important step in modifying and remineralizing terrestrially-derived DOM, as shown in individual examples and indirect mechanistic evidence. Important classes of marine-derived DOM probably also enter this cycle. This project will quantify total photooxidative processes as oxygen consumption, by (1) direct O2 uptake measurements where sensitivity permits, and (2) using an indirect method sensitive enough for "blue water" and for low-reactivity coastal water studies. The results will provide much-needed quantitative evaluation of the role of photooxidation in oceanic carbon and oxygen cycles. Oxygen consumption, closely related to DOM oxidation, will be measured in coastal and estuarine waters and in organic matter concentrated by hydrophobic adsorption. Direct O2 uptake will be measured using pulsed polarographic electrodes with automated data acquisition. A sensitive new indirect technique, calibrated empirically against direct measurements, will quantify fluxes of the primary O2 -consuming species in "blue" and low-activity coastal waters. Effects of variables such as wavelength, light intensity, temperature, oxygen concentration, and prolonged photolysis on O2 consumption rates will be investigated to understand their (bio) geochemical significance and to identify the major mechanisms involved in O2 uptake/C remineralization.