Atmospheric deposition of inorganic nutrients to the Western North Pacific Ocean

Abstract

We evaluated the potential impacts of atmospheric deposition on marine productivity and inorganic carbon chemistry in the northwestern Pacific Ocean (8-39 degrees N, 125-157 degrees E). The nutrient concentration in atmospheric total suspended particles decreased exponentially with increasing distance from the closest land-mass (Asia), clearly revealing anthropogenic and terrestrial contributions. The predicted mean depositional fluxes of inorganic nitrogen were approximately 34 and 15 mu mol m(-2) d(-1) to the west and east of 140 degrees E, respectively, which were at least two orders of magnitude greater than the inorganic phosphorus flux. On average, atmo-spheric particulate deposition would support 3-4% of the net primary production along the surveyed tracks, which is equivalent to similar to 2% of the dissolved carbon increment caused by the penetration of anthropogenic CO2. Our observations generally fell within the ranges observed over the past 18 years, despite an increasing trend of atmospheric pollution in the source regions during the same period, which implies high temporal and spatial variabilities of atmospheric nutrient concentration in the study area. Continued atmospheric anthropogenic nitrogen deposition may alter the relative abundances of nitrogen and phosphorus. (C) 2021 Elsevier B.V. All rights reserved.