Degradation of Colloidal Organic Material and the Formation of Semi-Refractory DOM

在海洋中已经观察到大量的胶体（亚微米粒子），它们被认为在几种地球化学反应中起着关键作用。初步实验得出的假设是，胶体在半难溶性有机物（DOM）的生成过程中起着至关重要的作用，这种有机物在真正不稳定的化合物（如游离氨基酸）和难溶性DOM之间的周转期为1000年。具体来说，假设与胶体相关的化合物比自由溶解的相同化合物降解得慢。将进行实验来验证这一假设，并获得更多关于自然发生的亚微米颗粒周转的信息。这些实验将检验：1)吸附在或被捕获在14c脂质体中的3h蛋白的降解，这些脂质体模拟由鞭毛虫产生的胶体（鞭毛虫粪便颗粒）；2) 3H-蛋白被吸附或被捕获在14c脂质体中，这些脂质体类似于鞭毛虫产生的胶体（鞭毛虫粪便颗粒）；2)降解吸附在天然胶体上的蛋白质。胶体的周转将通过双放射性标记脂质体和14c标记鞭毛粪便颗粒的降解来估计。这些实验将在特拉华河口和沿海水域进行，在春天开花和夏天，这应该会得到一系列的胶体类型，浓度和降解率。这项工作将提供对胶体周转，DOM在海洋环境中的降解，以及可能导致真正难降解DOM形成的过程的见解。

9416740 KIRCHMAN Large numbers of colloids (submicron particles) have been observed in the ocean and are thought to play key roles in several geochemical reactions. Preliminary experiments have led to the hypothesis that colloids are crucial in the production of semi- refractory dissolved organic matter (DOM) with turnover times between truly labile compounds (e.g. free amino acids) and refractory DOM with turnover times 1000 years. Specifically it is hypothesized that compounds associated with colloids are degraded slower than the same compound freely dissolved. Experiments will be conducted to test this hypothesis and to gain more information about turnover of naturally-occurring submicron particles. These experiments will examine: 1) degradation of 3H-protein sorbed to or trapped inside 14C-liposomes which mimic colloids produced by flagellates (flagellate fecal pellets); 2) degradation of 3H- protein sorbed to or trapped inside 14C-liposomes which mimic colloids produced by flagellates (flagellate fecal pellets); and 2) degradation of protein adsorbed to natural colloids. Turnover of colloids will be estimated from the degradation of dual radiolabeled liposomes and from 14C-labeled flagellate fecal pellets. These experiments will be conducted in the Delaware Estuary and coastal waters during the spring bloom and summer, which should give a range of colloid types, concentrations and degradation rates. The work should provide insight into colloid turnover, the degradation of DOM in oceanic environments, and perphaps processes leading to the formation of truly refractory DOM.