Continental Shelf Benthic Oxygen Fluxes Determined by Eddy Correlation in the Presence of Wave Motions

在过去的十年中，位于北方加州海流系统的俄勒冈州-华盛顿州大陆架的广泛部分在夏季上升流季节受到严重缺氧的影响。 大陆架上溶解氧的质量平衡表明，沉积物的摄氧量大于使用传统底栖室和微剖面测量底栖通量的估计值。 这种不平衡的最可能的解释是在主要的物理和生物过程中的时间和空间的变化，有助于货架上的氧气利用率的不确定性。 俄勒冈州州立大学的一名科学家计划利用涡动相关技术确定俄勒冈州大陆架内和中的海底氧通量的大小和变化以及波浪引起的运动对这些通量的影响。 这种技术假定通过测量海底上方氧气波动和垂直速度波动之间的协方差可以获得直接的垂直通量估计。 为了实现这一目标，将进行波浪水槽实验和使用EC着陆器的现场测量。 最初，在高能波的存在下的EC测量将在大波浪水槽在俄勒冈州立大学的欣斯代尔波研究设施，这是其在北美最大的波通道。波浪水槽实验的目的是通过实验验证数据收集、平均和坐标旋转的最佳方法，以在波浪和桑迪床存在的情况下获得无偏通量。 此外，还将采用波浪-湍流分解法，以量化波浪对海底氧交换的贡献，并记录随波高逐步增加和减少而演变的床形和孔隙水剖面序列。一旦波浪水槽实验完成，将进行四次为期8天的研究航行，在3年的春季、夏季和秋季条件下对俄勒冈州大陆架进行测量。目标地点的特点是水深25至85米处有透水砂，并可能出现波纹。辅助测量将包括底层水溶解氧、营养物、色素浓度、温度和盐度，而沉积物芯将被二次取样，用于整体渗透率测量和210 Pb、有机碳、氮、粒度和色素的分布。这位科学家计划与美国和智利的科学家合作，参与孔塞普西翁和俄勒冈州（密歇根州）近海低氧沃茨的微生物倡议。LOCO）项目。 作为该项目的一部分，将支助和培训一名研究生。

Within the last decade, broad sections of the Oregon-Washington continental shelf located in the northern California Current System have been affected by severe hypoxia during the summer upwelling season. Mass balances of dissolved oxygen on the shelf indicate oxygen uptake of sediments is greater than estimated from benthic flux measurements using traditional benthic chambers and microprofiles. The most probable explanation for this inbalance is uncharacterized temporal and spatial variability in the major physical and biological processes contributing to on-shelf oxygen utilization. A scientist from Oregon State University (OSU) plans to determine the magnitude and variability of benthic oxygen fluxes on the inner and middle Oregon shelf and the contribution of wave-induced motions to these fluxes using the eddy correlation (EC) technique. This technique assumes that a direct vertical flux estimate can be obtained by measuring the covariance between fluctuations of oxygen and fluctuations of vertical velocity above the seabed. To attain the goal, both wave flume experiments and field measurements using the EC lander will be carried out. Initially, EC measurements in the presence of energetic waves will be studied in the large wave flume at OSU's Hinsdale Wave Research Facility which is the largest wave channel of its type in North America. The purpose of the wave flume experiments is to experimentally verify the best approaches to data collection, averaging, and coordinate rotation to derive unbiased fluxes in the presence of waves and a sandy bed. In addition, the wave-turbulence decomposition method will be applied to quantify wave contributions to seafloor oxygen exchange and to document the sequence of bedforms and pore water profiles that evolve in response to stepwise increases and decreases in wave height. Once the wave flume experiments have been completed, four 8-day research cruises will be carried out to make measurements on the Oregon shelf over 3 years during spring, summer and fall conditions. The sites to be targeted are characterized by permeable sands at 25 to 85 m water depth and can exhibit ripples. Ancillary measurements will include bottom water dissolved oxygen, nutrients, pigment concentration, temperature and salinity, whereas sediment cores will be subsampled for bulk permeability measurements and profiles of 210Pb, organic carbon, nitrogen, grain size, and pigments.As regards broader impacts, the scientist plans to collaborate with U.S. and Chilean scientists involved in the Microbial Initiative in Low Oxygen waters off Concepcion and Oregon (MI-LOCO) project. One graduate student would be supported and trained as part of this project.