Chemical Characterization and Reactivity of Dissolved Organic Matter in Seawater

溶解有机物（DOM）在海洋碳循环中的核心作用及其对众多物理、化学和生物过程的影响已被广泛认识，但关于DOM的来源、反应性和循环的基本问题仍有待解答。这些问题的许多答案都隐藏在DOM的化学结构中，但DOM的表征是具有挑战性的，因为海水中的浓度低，盐丰富。新方法的分离和化学表征DOM开始转变这一主要的碳库。切向流超滤已成为分离不同大小的海洋有机物的一种有效方法。近年来在超滤材料表征方面的努力为海洋DOM提供了丰富的新信息。未来三年的研究将集中在海水DOM的表征上，并以过去三年超滤DOM表征研究的主要成果为基础。本研究的主要目的是：1)研究海洋有机物的大小、组成和微生物反应性之间的关系；2)表征海洋中陆源DOM的分布和循环。

The central role of Dissolved Organic Matter (DOM) in the ocean carbon cycle and the influence of DOM on numerous physical, chemical, and biological processes are widely recognized, but fundamental questions about the sources, reactivity, and cycling of DOM remain to be answered. Many of the answers to these questions lie hidden within the chemical structures of DOM, but characterization of DOM is challenging because concentrations are low and salts are abundant in seawater. Novel approaches to the isolation and chemical characterization of DOM are beginning transformations of this major carbon reservoir. Tangential-flow ultrafiltration has emerged as a powerful approach for the isolation of different size classes of marine organic matter. Recent efforts in the characterization of ultrafiltered material have provided a wealth of new information about marine DOM. Over the next three years research will focus on the characterization of seawater DOM and build upon major findings of the past three years of research on the characterization of ultrafiltered DOM. The major objectives of the proposed research are: 1) to investigate relationships among size, composition, and microbial reactivity of marine organic matter, and 2) to characterize the distribution and cycling of terrigenous DOM in the ocean.