Evaluating the Effects of High Particulate Fluxes on Chemical Processes Occurring at the Amazon River/Ocean Boundary

这项提案是对现有拨款的延续，该拨款题为“评估亚马逊河/海洋边界高颗粒物通量的影响”，是AMasSeds(多学科亚马逊大陆架沉积物研究)项目的一部分。成功地完成了三次前往亚马逊大陆架的考察航行(8月、1990年2月、1990年5月和1991年11月)。这种了解亚马逊河/海洋边界活跃的化学、物理和地质过程的时间序列方法使研究人员能够解决河流流量、潮汐再悬浮、当地风应力和海岸洋流强度对颗粒相关过程的不同影响。这项建议中描述的具体研究主题包括：1)评估悬浮泥沙浓度对营养物质和碳的生物吸收和再生的影响；2)从颗粒和沉积物向水柱释放镭同位素，并将其用于跟踪海床/水柱交换过程；3)从大陆架水域中清除颗粒活性元素；4)河流/海洋混合过程中的铀循环；5)根据碳的分布和稳定的同位素数据追踪亚马逊陆架上的生物和物理过程。对水柱和海床中放射性示踪剂的测量使调查人员能够在不同的时间尺度(从几天到几百年)描述其中许多过程的特征。这项提案要求为另外两年的研究提供支助，这些研究将用于完成数据分析、建立单独的数据集、模拟初步结果，并将实地测量结果与参与该项目的其他研究小组结合起来。

This proposal is a renewal for the existing grant entitled "Evaluating the Effects of High Particulate Fluxes at the Amazon River/Ocean Boundary," which is part of the AmasSeds (A Multi- Disciplinary Amazon Shelf SEDiment Study) Project. Three research cruises to the Amazon shelf (August 1989; February, 1990; May 1990; and November, 1991) have been completed successfully. This time series approach to understanding the chemical, physical, and geological processes active at the Amazon River/ocean boundary enables the investigators to resolve the variable influences of river discharge, tidal resuspension, local wind stress, and the intensity of coastal currents on particle-associated processes. The specific topics of research described in this proposal include: 1) evaluating the effects of suspended sediment concentration on the biological uptake and regeneration of nutrients and carbon; 2) the release of radium isotopes to the water column from particles and sediments and their use in tracking seabed/water column exchange processes; 3) scavenging of particle-reactive elements from continental shelf waters; 4) uranium cycling during river/ocean mixing; and 5) tracing biological and physical processes on the Amazon shelf based on the distribution of carbon and stable isotopic data. Measurements of radioactive tracers in the water column and seabed enable investigators to characterize many of these processes on a variety of time scales (ranging from days to hundreds of years). This proposal requests support for two additional years of research, which will be used to complete data analyses, work up individual data sets, model the initial results, and integrate the field measurements with the other research groups taking part in the project.