Edward T. Peltzer; Monterey Bay Aquarium Research Institute

"Distribution, Sources and Sinks of Dissolved Organic Matter in the Southern Ocean"

The principal objectives of this proposal are: (1) to determine via shipboard measurement of both dissolved and total organic carbon (DOC/TOC) the spatial and temporal distribution of dissolved organic matter (DOM) in the Southern Ocean; (2) to identify the sites of net DOM production and export; (3) to estimate rates of net DOM production and export; (4) to estimate rates of bacterial remineralization of DOM; and (5) to place these rates in the context of the global carbon cycle. The net rates of DOM production and consumption will be estimated by a combination of in situ measurements and shipboard incubation experiments. Large scale rates will be calculated from a combination of simple box and advection diffusion models. Routine sample collection will be accomplished via 100 mL samples drawn from 10L Niskin bottles on the CTD rosette. The incubation experiments require on the order of 520L; these samples can be obtained either from multiple 10L niskin bottles or from the larger GoFlo bottles used on the trace metal clean rosette. This work will be conducted in collaboration with the study conducted by Drs. Dennis Hansell and Craig Carlson. These two studies offer complementary approaches: whereas the emphasis of this study is on making large scale surveys and repeating these surveys on a seasonal basis, their study emphasizes process orientated measurements with a more intense effort in determining bacterial remineralization rates. In order to provide maximal coverage of the proposed cruises, and to best address the objectives of our respective studies, we have developed the attached plan for cruise participation.