INORGANIC NITROGEN OVER THE WESTERN NORTH ATLANTIC OCEAN

The concentrations of the reactive nitrogen species NO2, NOx(= NO + NO2), NOy (the sum of all compounds of nitrogen and oxygen with the exception of N2O), particulate NO3-, and volatile NO3- were measured from ship and aircraft platforms over the western North Atlantic Ocean as part of the GCE/CASE/WATOX experiment. Air masses sampled were divided into continentally influenced and typical marine on the basis of trajectories, and radon and black carbon measurements. From the NO3- measurements on size separated aerosol and the altitude variations of volatile NO3- and particulate NO3-, a significant interaction between volatile NO3- and sea salt aerosol was indicated. The average marine concentrations measured were: 18 nmol m(-3) for NO2, 29 nmol m(-3) for NOx, 46 nmol m(-3) for NOy, and 10 nmol m(-3) for total r inorganic NO3-. The reactive nitrogen species were present at concentrations some 40 times those encountered in the remote Pacific Ocean, whereas the inorganic NO3- was only 3 times higher.