The major focus of this one.year research period will be a synthesis of previously collected data on carbon and nitrogen cycling in three wetland habitats of the Barataria Basin, Louisiana . the freshwater upper basin, the brackish middle basin and the saline lower basin. In addition to the synthesis of extant data, a small field research effort will do two things: 1) determine the importance of fertilizers and sewage as nitrogen sources to Barataria Basin; and 2) determine the amount of a denitrification product, N.2, that is trapped in the sediments. The synthesis will include modeling at two hierarchical levels; detailed process level models for each of the three major habitats in the basin, and models that are less detailed, but link the three major habitats. The models will be validated with extant and newly collected field data that will not have been used in model development. Newly collected field data will result from state.of.the.art measurement technologies. For example, stable isotope ratios of nitrogen (.1.5N/.1.4N) will be used to distinguish fertilizer and sewage nitrogen sources from each other. The significance of this research is that it will provide important basic information on the functioning of one of our country's major wetland ecosystems. Data on the carbon and nitrogen cycles and how humankind is changing them are necessary if we are going to wisely manage this valuable wetland resource. Dr. Patrick and his colleagues at Louisiana State University have productive records in wetlands research. The institutional support available to them is of very high quality,
