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

P.I.Hickey，Barbara(UW)项目概述本提案侧重于高生产力的东部边界哥伦比亚河羽流。这个羽状物足够大，具有区域重要性，但又足够小，可以确定影响河流羽状物的主要过程，并便于与羽状物以外的区域进行比率比较。拟议的研究将综合附近的风力驱动COOP研究的结果，以及附近GLOBEC和ECOHAB项目的结果，以提供关于独特的层结、浑浊、混合环境和河流羽状物的营养物质对生物地球化学过程速率变化的明确新信息。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，这项研究允许分离羽流特有的过程，因此过程结果可以直接应用于其他羽流。结果也可以与更富营养化、受浮力影响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，羽流中浮游植物的增长率超过由相同上升流常量营养素推动的羽流以外附近地区的增长率。-羽流加强了浮游生物和营养物质的跨境运输。-羽流特有的营养物质(铁和二氧化硅)改变和提高附近货架的生产力。拟议的战略是比较羽流内和羽流外的生产率，在河口以北生产力较高的大陆架(华盛顿州)和生产力较低的南方大陆架(俄勒冈州)。这项研究的结果解决了一个重要的问题，即为什么上升风较弱的大陆架比风力较强的大陆架更具生产力。

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.