Bioavailability of atmospheric organic nitrogen deposition to coastal phytoplankton

Atmospheric dissolved organic nitrogen has recently gained attention as a significant additional source of "new" N loading to the oceans. The effect of atmospheric N on marine productivity depends on the biological availability of both inorganic and organic N forms. Event-based measurements for coastal North Carolina showed that similar to 30% of rainwater N concentration and deposition was organic N. Enrichment bioassay results suggested that similar to 20-30% of atmospheric organic N is available to primary producers on short (hours to days) time scales. Atmospheric N loading estimates, therefore, should include all available N inputs to properly assess the impact of N deposition on coastal and oceanic primary productivity.