Measurement of Oxygen Uptake from Marine Sediments by Eddy Correlation

在自然海洋环境中，氧气向沉积物中的传输是由上覆溶液的湍流传输运动尺度介导的，分子扩散慢了几个数量级，实际上是一个无关紧要的术语。沉积物耗氧量是评价有机质分解速率的重要参数，也是控制沉积物厌氧呼吸过程中产生的还原剂如NH 4+、Mn 2+、Fe 2+、HS-、FeS等氧化的重要因素。通风和灌溉的沉积层无论是波引起的泵送或生物扰动活动的过程中，可能会被量化的沉积物O2 uptake.This建议将扩展和探索最近提出的方法正在共同开发的PI与同事在马克斯普朗克海洋微生物学研究所（不莱梅）。该技术涉及到相关的溶解氧的时变浓度，测量快速响应微电极，在沉积物边界层内的几厘米的表面与本地感测的垂直速度分量也采样在高频率的声学多普勒测速仪（ADV）。涡动相关方法与大气科学家测量行星边界层标量（例如热量、水分（动量）和痕量气体）通量所使用的类似技术有直接的相似之处。理论和实践的考虑适应水生系统的基本方法进行了讨论，并将探讨在浅沿海实地在丹麦（奥胡斯湾）。

ABSTRACTOCE-0221259Oxygen transport into sediments in natural marine environments is mediated by the turbulent transport scales of motion of the bulk overlying solution, molecular diffusion being orders of magnitude slower and a virtually insignificant term. The oxygen consumption by sediments, conventionally quantified by either laboratory measurements on recovered cores or by the artifice of an in-situ enclosure experiment, is a key parameter in assessing organic matter decomposition rates and also controls the oxidation of sediment reductants such as NH4+, Mn2+, Fe2+, HS-, FeS etc produced during anaerobic respiration. Ventilation and irrigation of sedimentary layers either by wave induced pumping or bioturbation activity are also processes that could potentially be quantified by more reliable measurements of sediment O2 uptake.This proposal will extend and explore a recently suggested approach being jointly developed by the PI together with colleagues at the Max Planck Institute for Marine Microbiology (Bremen). The technique involves correlating the time varying concentration of dissolved oxygen, measured by fast response microelectrodes, in the sediment boundary layer within a few cm of that surface with locally sensed vertical velocity components also sampled at high frequency by acoustic Doppler velocimetry (ADV). An eddy correlation approach has direct analogues with similar techniques that are used by atmospheric scientists measuring scalar (e.g. heat, moisture (momentum) and trace gas) fluxes in the planetary boundary layer. Theoretical and practical considerations for the adaptation of the basic approach into aquatic systems are discussed and will be explored at shallow coastal field sites in Denmark (Aarhus Bay).