Benthic Metabolism in Continental Margin Sediments: Controls on Reaction Rate and Potential Consequences

小行星9416626 在这个项目中，研究人员将解决全球碳循环的一个主要问题：是什么决定了世界海洋初级生产产生的有机碳在多大程度上能在矿化作用中存活下来并被埋在海底沉积物中？ 该项目将继续研究人员过去在西太平洋边缘的两个地区的工作，一个在美国太平洋西北部，另一个在墨西哥西北部海岸。它有 通常认为，颗粒有机物的量 沉积物-水界面附近的物质决定了有机矿化或氧化的速度;这一过程是由异养细菌介导的，它们利用溶解氧或硝酸盐作为氧化剂。 然而，在这项研究中，研究人员还将探讨当水柱氧浓度低时，溶解氧和硝酸盐（而不是有机物）的浓度可能实际上控制矿化速率。为了澄清这些问题，该项目将涉及实地测量有机沉积速率、沉积物中的化学反应和（通过直接测量）沉积物-水界面的溶质通量。

9416626 Devol In this project, the investigator will address one of the major questions on the global carbon cycle: What determines the extent to which organic carbon produced by primary production in the world ocean survives mineralization and is buried in seafloor sediments? The project will continue the investigator's past work in two regions of the western Pacific margin, one off the U.S. Pacific Northwest, the other off the coast of northwestern Mexico. It has commonly been assumed that the amount of particulate organic matter near the sediment-water interface determines the rate of organic mineralization, or oxidation; the process is mediated by heterotrophic bacteria that use either dissolved oxygen or nitrate as oxidant. However, in this study the investigator will also explore the possibly that, when water column oxygen concentrations are low, the concentrations of dissolved oxygen and nitrate (rather than organic matter) may actually control mineralization rates. To clarify these issues, the project will involve field measurements of the rates of organic sedimentation, chemical reactions in the sediments, and (by direct measurement) solute fluxes across the sediment-water interface.