{"596151":{"#nid":"596151","#data":{"type":"event","title":"Quantifying Nitrogen Fixation and it\u0027s Contribution to Export Production in the South Pacific Using Geochemical Tools","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003EEAS Fall 2017 Seminar Series presents Dr. Angie Knapp, Florida State University\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EIdentifying the spatial distribution of the largest di-nitrogen (N\u003Csub\u003E2\u003C\/sub\u003E) fixation fluxes to the ocean remains a critical goal of chemical oceanography because the answer informs our understanding of the environmental sensitivities of N\u003Csub\u003E2\u003C\/sub\u003E fixation as well as the capacity for the dominant marine nitrogen (N) source and sink processes to respond to each other and thus influence the global carbon cycle and climate.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EI will present results from studies in both the western and eastern South Pacific, regions of particular interest because of relatively low nitrate to phosphate concentration ratios in surface waters, as well as large gradients in the flux of atmospheric dust to surface waters.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EMy work quantifies rates of N\u003Csub\u003E2\u003C\/sub\u003E fixation and its importance for supporting export production using d\u003Csup\u003E15\u003C\/sup\u003EN budgets, however, \u003Csup\u003E15\u003C\/sup\u003EN\u003Csub\u003E2\u003C\/sub\u003E incubation-based N\u003Csub\u003E2\u003C\/sub\u003E fixation rates as well as molecular studies were done in parallel by other groups in both field studies. N\u003Csub\u003E2\u003C\/sub\u003E fixation rates in the eastern tropical South Pacific were very low, and did not support the \u0026ldquo;P*\u0026rdquo; hypothesis based on modeling of nutrient distributions and fluxes, and indicate that iron likely limits N\u003Csub\u003E2\u003C\/sub\u003E fixation in the region. N\u003Csub\u003E2\u003C\/sub\u003E fixation rates in the western tropical South Pacific were much higher at stations proximal to significant atmospheric dust sources, and at some stations supported a majority of export production, a unique result.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EAdditionally, d\u003Csup\u003E15\u003C\/sup\u003EN budget-based N\u003Csub\u003E2\u003C\/sub\u003E fixation rates were typically lower than \u003Csup\u003E15\u003C\/sup\u003EN\u003Csub\u003E2\u003C\/sub\u003E incubation-based N\u003Csub\u003E2\u003C\/sub\u003E fixation rates, although molecular characterization of diazotroph abundance and activity agreed more closely with d\u003Csup\u003E15\u003C\/sup\u003EN budget-based N\u003Csub\u003E2\u003C\/sub\u003E fixation rates.\u0026nbsp;\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"A seminar by Dr. Angela Knapp, School of Earth and Atmospheric Sciences Fall 2017 Seminar Speaker Series"}],"uid":"34458","created_gmt":"2017-09-19 16:20:45","changed_gmt":"2017-09-25 17:21:19","author":"nlawson3","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2017-10-05T12:00:00-04:00","event_time_end":"2017-10-05T12:55:00-04:00","event_time_end_last":"2017-10-05T12:55:00-04:00","gmt_time_start":"2017-10-05 16:00:00","gmt_time_end":"2017-10-05 16:55:00","gmt_time_end_last":"2017-10-05 16:55:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"hg_media":{"596145":{"id":"596145","type":"image","title":"Knapp Seminar","body":null,"created":"1505835768","gmt_created":"2017-09-19 15:42:48","changed":"1505835768","gmt_changed":"2017-09-19 15:42:48","alt":"","file":{"fid":"227193","name":"Knapp_180.jpg","image_path":"\/sites\/default\/files\/images\/Knapp_180.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/Knapp_180.jpg","mime":"image\/jpeg","size":9543,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/Knapp_180.jpg?itok=SoirXIT2"}}},"media_ids":["596145"],"groups":[{"id":"364801","name":"School of Earth and Atmospheric Sciences (EAS)"}],"categories":[],"keywords":[{"id":"175623","name":"EAS Seminar"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1795","name":"Seminar\/Lecture\/Colloquium"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"174045","name":"Graduate students"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003Enatasha.lawson@eas.gatech.edu\u003C\/p\u003E\r\n","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}