Laboratory Studies on the Role of Maine Colloidal Organic Material (COM) in the Scavenging of Thorium

9416088霍尼曼传统观点认为，钍与所有非水相配体(即大颗粒和胶体)的反应程度相同，其在这些配体中的分配与配体浓度成正比。然而，有新的证据表明，钍与“粒子”池的不同成分发生了不同的反应。这一证据表明，在海洋胶体物质(COM)池中，钍可能是高度分馏的，因此，有一条复杂的途径通过COM残留物。例如，最近的工作指出了海洋胶体行为令人费解的一个方面：从U-238/Th-234不平衡估计的胶体周转时间对于所有分子量组分来说相对较短：几周或更短取决于环境；相反，14C数据给出了低分子量胶体的旧表观年龄和高分子量组分的现代年龄(Santschi等人，1994年)。了解钍与COM中各组分之间的化学关系，应能提供作为碳循环中各组分的示踪剂的钍。

9416088 HONEYMAN Conventional wisdom has held that thorium reacts with all non- aqueous phase ligands (i.e., macroparticles and colloids) to the same degree with thorium distribution among those ligands being proportional to ligand concentration. There is, however, emerging evidence that thorium reacts differently with the various compo- nents of the "particle" pool. This evidence suggests that thorium may be highly fractionated within the pool of marine colloidal material (COM) and, thus, has a complicated path through the res- ervior of COM. For example, recent work points to a puzzling aspect of marine colloid behavior: colloid turnover times estimated from U-238/Th-234 disequilibrium are relatively short for all molecular weight fractions: several weeks or less depending on the environment; in contrast, 14C data yields old apparent ages for low molecular weight colloids and modern ages for the higher MW fractions (Santschi et al., 1994). Understanding the chemical relationship between thorium and components of COM should provide access to thorium as a tracer for components within the carbon cycle.