Collaborative Research: Productivity, Biogeochemical Transformations and Cross-margin Transport in an Eastern Boundary Buoyant Plume Region

P.I. Hickey, Barbara （UW）项目概述本提案的重点是高产的东边界哥伦比亚河羽流。该羽流足够大，具有区域重要性，但又足够小，可以确定影响河流羽流的主要过程，并便于与羽流以外的地区进行速率比较。拟议的研究将整合附近风力驱动的CoOP研究结果，以及附近GLOBEC和ECOHAB项目的结果，以提供关于生物地球化学过程速率变化的明确新信息，通过独特的分层、浊度、河流羽流的混合环境和营养物。此外，由于哥伦比亚河在生长季节没有为羽流提供显著的陆源硝酸盐，因此该研究允许羽流特有过程被隔离，因此过程结果可以直接应用于其他羽流。结果还可以与富营养化程度更高、受浮力影响更大的沿海地区进行对比。拟议的研究将解决三个假设：-在上升流期间，羽流内浮游植物的生长速度超过了羽流外附近地区的浮游植物生长速度，受到相同的上升流大量营养物质的推动。-羽流促进了浮游生物和营养物的跨缘运输。-羽毛特有的营养素（铁和sio2）改变并提高附近架子上的生产力。拟议的策略是比较羽流内部和羽流外部的产量，在河口以北（华盛顿州）生产力较高的大陆架和南部（俄勒冈州）生产力较低的大陆架上。这项研究的结果解决了一个重要的问题，即为什么有较弱上升流风的大陆架比有较强风的大陆架生产率更高。

P.I. Hickey, Barbara (UW)Project Summary This proposal focuses on the highly productive Eastern Boundary Columbia river plume. This plume is sufficiently large to be of regional importance, yet small enough to allow determination of dominant processes affecting river plumes, and to facilitate rate comparisons with regions outside the plume The proposed study will integrate results from the nearby wind-driven CoOP study, as well as with those from nearby GLOBEC and ECOHAB projects to provide definitive new information on alteration of rates of biogeochemical processes by the unique stratification, turbidity, mixing environment and nutrients of a river plume. Moreover, because the Columbia River provides no significant terrigneous nitrate to the plume in the growing season, this study allows plume-endemic processes to be isolated and hence process results can be directly applied to other plumes. Results can also be contrasted with more eutrophic, buoyancy-influenced coastal areas.The proposed study will address three hypotheses: - During upwelling the growth rate of phytoplankton within the plume exceeds that in nearby areas outside the plume being fueled by the same upwelling macronutrients. - The plume enhances cross-margin transport of plankton and nutrients. - Plume-specific nutrients (Fe and SiO4) alter and enhance productivity on nearby shelves. The proposed strategy is to compare production rates within the plume and outside the plume, on the more productive shelf to the north of the river mouth (Washington) and the less productive shelf to the south (Oregon). Results from this study address important question as to why a shelf with weaker upwelling winds is more highly productive than a shelf with stronger winds.