Burial and Preservation of Phosphorus in Marine Sediments: Response to Bottom Water Oxygenation

本研究将研究底水氧浓度对海底成岩过程和海洋沉积物中磷元素通量的影响。这项研究的重点源于初步数据，这些数据表明，海洋沉积物中磷的整体埋藏和保存在很大程度上取决于沉积物上覆水域的氧浓度。这些研究表明，缺氧的底水促进了沉积物的磷再生，降低了总体埋藏效率。如果这种效应能够得到证实，它对沿海地区的富营养化和P的长期循环具有重要意义，特别是在广泛的海洋缺氧期间。在墨西哥湾和大普吉特海湾地区被缺氧和缺氧底水覆盖的地点将使用原位底栖生物通量室，孔隙水和沉积物测量进行检查。P和相关元素的稳态通量将从原位底栖室实验中确定。底栖生物通量将与沉积物埋葬通量相结合，以计算不同研究地点的P埋葬效率。这项研究的一个主要目的是确定负责埋葬和保存磷的机制，以及它们在有氧和没有氧的情况下可能有何不同。将特别关注可能对变化的氧化还原条件敏感的过程，如细菌和溶解铁对P的循环。在野外和随后的实验室研究中收集的数据将被整合到一个数值输运反应模型中，以约束早期磷成岩动力学。这些结果将用于评估沉积P通量变化对长期全球海洋生产力的潜在影响。

9415563 INGALL This research will study the effect of bottom water oxygen concentration on seafloor diagenetic processes and elemental fluxes of phosphorous in marine sediments. The focus of the research stems from preliminary data suggesting that the overall burial and preservation of phosphorus in marine sediments is strongly dependent on the concentration of oxygen in waters overlying the sediments. These studies indicate that oxygen depleted bottom waters enhance phosphorus regeneration from sediments, diminishing overall burial efficiency. If this effect can be verified it has important implications for eutrophication in coastal regions and for the long term cycling of P especially during periods of widespread ocean anoxia. Sites overlain by anoxic and oxic bottom waters in the Gulf of Mexico and the greater Puget Sound region will be examined using in situ benthic flux chambers, pore water and sediment measurements. Steady state fluxes of P and associated elements will be determined from in situ benthic chamber experiments. Benthic fluxes will be combined with sediments burial fluxes in order to calculate P burial efficiencies for the different study sites. A major objective of this research is to identify the mechanisms responsible for the burial and preservation of phosphorus and how they may differ in the presence and absence of oxygen. Particular attention will be paid to processes potentially sensitive to changing redox conditions such as the cycling of P by bacteria and dissolved iron. Data gathered during the field and subsequent lab studies will be integrated into a numerical transport reaction model in order to constrain the kinetics of early phosphorus diagenesis. The results will be used to evaluate the potential effects of variations in sedimentary P flux on long term global marine productivity.