Nitrogen Fixation from vertical CTD profile rosette samples by stable-isotope mass spectrometry on cruise D346 dataset https://portal.medin.org.uk/portal/start.php?tpc=006_407ff26103ef57a587c930fdc80cec63 Nitrogen Fixation was determined from samples collected during CTD profiles at the surface and chlorophyll maximum once per day from the North Atlantic at approximately 24.5 degrees North on cruise D346 between 5th January and 19th February 2010. The samples were incubated at sea-surface temperature for 24 hours, filtered onto ashed-GF/F's and dried in oven at 50 degrees for further 24 hours. The data are being used as part of a wider study in the role iron has in nitrogen fixation. David Honey collected these data as part of his PhD, supervised by Martha Gledhill and Eric Achterberg. 20180518 20160210