The Application of Thermal Ionization Mass Spectrometry to the Study of Thorium Scavenging in the Oceans

这项建议旨在研究Th在溶解相和各种自然产生的胶体和悬浮颗粒表面之间的分配。这些信息将被用来更详细地研究清除的机制。特别是，这种测量将允许将吸附到颗粒表面的过程与胶体和悬浮颗粒的聚集和解聚分开。建议的Th-230和Th-232测定需要提高分析灵敏度%，因为这些同位素的传统放射化学分析需要数千升海水。建议开发利用热电离质谱(TIMS)进行这些分析的技术。因此，本研究可使用亚升(Th-232)和1-10升(Th-230)的天然海水样品。将对不同颗粒制度下的若干样本进行检查，范围从开阔海洋的垂直剖面，到在生物活动强烈时期(春季和夏季)和物理再悬浮时期(秋季和冬季)收集的沿海水域。

This proposal is aimed at examining the partitioning of Th between the dissolved phase and various naturally occurring colloidal and suspended particulate surfaces. This information will be used to examine in more detail the mechanisms of scavenging. In particular, such measurements would allow for a separation of the processes of sorption onto particle surface from the aggregation and disaggregation of colloids and suspended particles. %%% Increased analytical sensitivity is needed for the proposed Th- 230 and Th-232 determinations, as traditional radiochemical analyses of these isotopes require thousands of liters of seawater. It is proposed to develop techniques which utilize thermal ionization mass spectrometry (TIMS) for these analyses. Sub-liter (for Th-232) and 1-10 liter (for Th-230) natural seawater samples could thereby be used for this study. A number of samples under differing particle regimes will be examined, ranging from vertical profiles in the open ocean, to coastal waters collected during periods of intense biological activity (spring and summer) and periods of physical resuspension (fall and winter).