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

两支前往秘鲁大陆边缘的探险队将调查 沉积物表面附近的微生物化学过程。 的 P.I：的将测量生物成分的通量， 沉积物-水界面与细菌垫活性有关， 有机质成岩作用，铁氧化还原循环，磷酸盐 降水和沉积反硝化作用。 所选 研究区（11 o 40“S -15 oS; 50 m-600 m） 持续上升流、初级生产力和沉积物有机质 碳;无处不在的微生物席;现代磷块岩;以及 近底层水中几乎为零的氧气和“硝酸盐缺乏” 柱 一个更小的是（1300平方米。Km at 13 o30'S），选择为 研究底栖过程将在一个底部导航的 阵列，为潜水作业提供详细的地图， 底层实验 通量将通过底栖通量获得 腔室（Landers）、微电极（Profiler）和mm级 孔隙水剖面（箱式岩心和全岩心挤压器）。 的 P.I.还将部署近底沉积物捕集器和海流捕集器。 测定运输速度和方向， 向极携带粒子的地球化学来源 底流 长期和短期的原位实验 海底将测试有关理论（1）磷灰石成核 （2）沉积物扰动与沉积物 饥饿;（3）片状分布的层状沉积物， 毡、有机碳和颗粒;以及（4）Fe-和O2-氧化还原 磷的反应。

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.