9413843 BENNER Research on the sources and reactions of dissolved organic matter (DOM) in seawater will focus primarily on the 20-30% of total dissolved organic matter which can be gently isolated in relatively large amounts by tangential-flow ultrafiltration. The three central objectives of research are: 1. To identify the biological sources and transformations of the major DOM components. 2. To elucidate compositional trends among DOM constituents of different size. 3. To characterize in detail the compositions and associations of the various organic materials comprising seawater DOM. Research to determine the biological and diagenetic origins of DOM will emphasis rapid processes occurring in the upper column where large differences in DOM concentrations and compositions are observed. A better understanding of compositional trends among dissolved organic materials of different size will help to delineate processes affecting DOM cycling and to judge how representative ultrafiltered isolates are of bulk DOM. More detailed characterizations of the compositions and forms of ultrafiltered DOM will aid in distinguishing its biological sources, identifying key transformations, and deconvoluting functional relationships among DOM constituents. This line of research has already provided new insights on both the reactive and refractory components of the immense seawater DOM pool and should continue to yield information useful over a wide range of oceanographic studies.
