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研究沉积物表面附近的生物地球化学过程。P.I.S将测量与细菌垫活动、有机质成岩作用、铁氧化还原循环、磷酸盐沉淀和沉积反硝化作用有关的生物成分在沉积物-水界面上的通量。所选择的研究区(11o40“S-15oS；50m-600m)具有较高的持续上升流、初级生产力和沉积物有机碳；普遍存在的微生物席；现代磷酸盐；近底水柱中接近于零的氧和硝酸盐亏损。较小的ARE(1300平方英尺)S)，被选中研究海底过程，将以底部导航阵列的盒子为核心，为潜水器作业和海底实验提供详细的地图。通量将通过海底通量小室(Landers)、微电极(剖面仪)和毫米尺度的孔隙水剖面(盒状岩心和全岩心压榨器)获得。S还将部署近底沉积物捕捉器和海流计，以确定向极地底流中携带的颗粒物的运移速度和方向以及颗粒的生物地球化学源。在海底进行的长期和短期现场实验将检验以下理论：(1)磷灰石的成核和溶解；(2)沉积物扰动和沉积物饥饿；(3)层状沉积物、席状物、有机碳和球团的片状分布；(4)Fe和O2-氧化还原驱动的磷反应。

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.