Sediment-Water Interface of the Peru Shelf: Biogenic Fluxes and Phosphorite Formation

两个前往秘鲁大陆边缘的探险队将调查沉积物表面附近的生物地球化学过程。pi: s将测量与细菌席活动、有机物成岩作用、铁氧化还原循环、磷酸盐沉淀和沉积反硝化有关的沉积物-水界面生物成分的通量。所选研究区（1140”S—15oS, 50 m—600 m）表现出高持续性上升流、初级生产和沉积有机碳；无处不在的微生物席；现代磷灰石;接近零的氧气和近底部水柱的“硝酸盐赤字”。面积较小的是1300平方英尺。选定用于研究底栖生物过程的区域，将在海底导航阵列中进行框芯，为潜水作业和海底实验提供详细的地图。通量将通过底生物通量室（Landers）、微电极（profiler）和毫米级孔隙水剖面（盒式岩心和全岩心挤压器）获得。私家侦探还将部署近海底沉积物陷阱和流速计，以确定移动速度和方向，以及极地海底流动中携带的颗粒的生物地球化学来源。在海底进行的长期和短期现场实验将检验以下理论：(1)磷灰石成核和溶解度；(2)泥沙扰动和缺沙；(3)层状沉积物、席状沉积物、有机碳和颗粒呈斑片状分布；(4) Fe-和o2 -氧化还原驱动磷反应。

Two expeditions to the Peru Continental Margin will investigate biogeo chemical processes near the sediment surface. The P.I:'s will measure the fluxes of biogenic components across the sediment-water interface linked to bacterial mat activity, organic matter diagenesis, iron redox cycling, phosphate precipitation and sedimentary denitrification. The selected study area (11o40"S - 15oS; 50 m -600 m) exhibits high persistent upwelling, primary production and sediment organic carbon; ubiquitous microbial mats; modern phosphorites; and near-zero oxygen and "nitrate deficit" in the near-bottom water column. A smaller are (1300 sq. Km at 13o30'S), selected to study benthic processes will be box cored in a bottom-navigated array to provide a detailed map for submersible operations and bottom experiments. Fluxes will be obtained with benthic flux chambers (Landers), microelectrodes (Profilers) and mm-scale pore water profiles (box cores and Whole-Core Squeezer). The P.I:'s will also deploy near-bottom sediment traps and current meters to determine transport velocities and directions and the biogeochemical sources of particles entrained in the poleward bottom flow. Both long- and short- term in situ experiments on the seabed will test theories concerning (1) apatite nucleation and solubility; (2) sediment disturbance and sediment starvation; (3) patchy distributions of laminated sediments, mats, organic carbon and pellets; and (4) Fe- and O2-redox driven phosphorus reaction.