Marine nitrogen fixation as a possible source of atmospheric water-soluble organic nitrogen aerosols in the subtropical North Pacific

Abstract. Water-soluble organic nitrogen (WSON) in marine atmospheric aerosols affect the water solubility, acidity, and light-absorbing properties of aerosol particles, which are important parameters assessing both climate impact biogeochemical cycling bioelements. Size-segregated surface seawater (SSW) samples were simultaneously collected over subtropical North Pacific to investigate origin WSON atmosphere. The fine-mode concentration (7.5 ± 6.6 ngN m−3) at 200–240∘ E along 23∘ N, defined as eastern (ENP), was significantly higher than that (2.4 1.9 135–200∘ E, western (WNP). Analysis stable carbon isotope ratio water-soluble (WSOC; δ13CWSOC) together with backward trajectory indicated most observed fine particles ENP originated from ocean surface. We found positive relations among nitrogen-fixation rate, dissolved (DON) SSW, concentrations. result suggests reactive (DON ammonium), produced exuded by nitrogen-fixing microorganisms contributed formation aerosols. This study provides new insights into role ocean-derived associated microbial activity.