Particle Export Fields in the Arabian Sea Derived from 234TH: 238U Disequilibria

小行星9310702 美国JGOFS阿拉伯海过程研究的主要研究目标之一是测量阿拉伯海颗粒物质，特别是颗粒有机碳的垂直和水平迁移率。 来自海洋表层的颗粒输出特别令人感兴趣，因为这是新的生物颗粒形成，放牧和物理改变的区域，然后进入分解循环，再生溶解的营养物质。 虽然一些调查人员将通过在不同深度放置开放的罐并测量随着时间的推移收集在其中的材料数量来进行这种估计，但这种努力有一些内在的不确定性。 本项目的主要研究者将以一种完全不同的方式处理估计海洋表面颗粒输出的问题，这将作为对沉积物捕集器估计的独立检查。 他的方法利用了这样一个事实，即溶解在海水中的铀会衰变，产生一种放射性的子体钍-234（半衰期为24天），它（不像铀）强烈地附着在粒子上。通过对混合上层水内部和下面的颗粒进行取样，测量其TH-234含量，并使用一些简单的数学模型，调查人员将能够估计混合层到深度的颗粒。 通过测量这些物质的碳和氮含量，他也将能够估计这两种元素的通量。 阿拉伯海地区的区域颗粒碳通量图片将建立从大约25个站收集的数据在两个季风季节（夏季和冬季）和两个季风间歇期。 ***

9310702 Buesseler One of the major research objectives of the U.S.JGOFS Arabian Sea Process Study is measurement of the vertical and horizontal transport rates of particulate material, especially particulate organic carbon, in the Arabian Sea. Particle export from the surface layers of the ocean is of particular interest because that is the zone where new biological particles are formed, grazed, and physically altered, and then enter the decomposition cycle that regenerates dissolved nutrients. Although some investigators will be making such estimates by setting out open canisters at different depths and measuring the amount of material that collects in them over time, such efforts have a number of built-in uncertainties. The principal investigator of the present project, will approach the problem of estimating particle export from the surface ocean in a radically different way, on that will serve as an independent check on the sediment trap estimates. His approach takes advantage of the fact that the dissolved uranium in seawater decays to produce a radioactive daughter, thoraium- 234 (half-life-24 days), which (unlike the uranium) strongly attaches to particles. By sampling particles within and below the mixed upper water layer and measuring their TH-234 content and using some simple mathematical models, the investigator will be able to estimate particle from the mixed layer to depth. By measuring carbon and nitrogen contents of these materials, he will also be able to estimate fluxes of those two elements. A regional particulate carbon flux picture for the Arabian Sea region will be built up by using the data from some 25 stations collected during two monsoonal seasons (summer and winter) and two intermonsoonal periods. ***