This project is a renewal of an investigation into the interaction between nitrogen and particle fluxes in the open ocean. The study features a time-series approach at a site 60 km southeast of Bermuda and the examination of nitrogen isotopic ratios as an in situ tracer. Results to date have provided a seasonal record for particle flux in the upper 350m and nitrogen isotope values for both suspended and sinking particles in the upper ocean. The proposed research focuses on several keu questions: 1) How does the magnitude of particle fluxes in the upper 500 m of the open ocean compare with other measures of new production and what is their seasonal and interannual variability? 2) What are the sources of "new" nitrogen to the euphotic zone and their seasonal, interannual, and regional variability? 3) How are sinking particles derived from suspended particles in the euphotic zone? 4) What is the nature of the coupling, if any, between suspended particles below the euphotic zone and particles sinking to this region?//
