Biogeochemical significance of Asian aerosol deposition in the southern East Sea (Sea of Japan)

Abstract

We presented results from the atmospheric investigation for metals and ions in the southern East Sea (35°-39°N and 129°-134°E), a marginal sea between Korea and Japan. Five-year observations (Oct. 2003-Oct. 2008) at Ulleung Island revealed that seasonal change of the atmospheric concentration and chemical composition was related to relative intensity of crustal and anthropogenic-originated aerosols. Atmospheric metal fluxes to the southern East Sea showed that Al and Co fluxes were similar to those to the Mediterranean Sea. On the other hand, anthropogenic-originated Pb and Zn fluxes were comparable to those over the North Sea.In addition, we investigated the transport patterns of aerosols on the east coast of Korea (37.58°N; 129.11°E) using backward trajectories and the associated concentrations of water-soluble ions (NO3-, NH4+ and nss-SO42-) and certain metals (Al, Na, nss-Ca, V, Zn and Pb). Air masses passing slowly over eastern China contributed higher concentrations of water-soluble ions than those fast-moving northwesterly winds. With measured NO3- and NH4+ concentrations during the period Mar. 2002-Feb. 2003, the dry N deposition flux was 460 mg N m-2 year-1. Taking into account wet N deposition flux of 613 mg N m-2 year-1, the atmospheric deposition flux of N over the southern East Sea was higher than that reported for the Mediterranean Sea and the North Sea. Contribution of atmospheric N deposition was -10% of new production on an annual scale, while it could account for over -25% of new production during the water column stratification seasons.