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

9415563这项研究将研究底水含氧量对海底成岩过程和海洋沉积物中磷元素通量的影响。这项研究的重点来自初步数据，该数据表明，海洋沉积物中磷的整体埋藏和保存强烈依赖于沉积物上覆水域中的氧气浓度。这些研究表明，氧气枯竭的底层水域增强了沉积物中磷的再生，降低了整体埋藏效率。如果能够证实这一影响，它对沿海地区的富营养化和磷的长期循环具有重要意义，特别是在海洋大范围缺氧期。墨西哥湾和大普吉特湾地区被缺氧和含氧底水覆盖的地点将使用原位底栖通量舱、孔隙水和沉积物测量进行检查。磷及其伴生元素的稳态通量将通过现场海底洞室实验来确定。将底栖通量与沉积物埋藏通量相结合，以计算不同研究地点的磷埋藏效率。这项研究的一个主要目标是确定磷的埋藏和保存机制，以及它们在有氧和无氧时的不同之处。将特别注意可能对变化的氧化还原条件敏感的过程，如细菌对磷的循环和溶解的铁。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传输反应模型中，以限制早期磷成岩作用的动力学。结果将被用来评估沉积磷通量变化对全球长期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.