Taiwan GEOTRACES Process Study: the Importance of Aerosol Deposition on the Seasonal Transformation of Trace Metal Distribution in the Western Philippine Sea

The Western Philippine Sea (WPS), receiving tremendous amount of anthropogenic and lithogenic aerosols during winter and spring seasons, provides an ideal platform to investigate the fates of aerosol trace metals and their seasonal transformation in the surface water. Two cruises were carried out in July 2013 and March 2014 at 8 same stations along 23.5 degree N transect in the WPS. The trace metal composition and distribution were determined in the samples of seawater, size-fractionated suspended particles, sinking particles, and aerosols to study their seasonal variations and transformation in the pools between the high and low deposition seasons. We found that trace metal fluxes through high aerosol deposition seasons were about one order of magnitude higher than the low deposition seasons in the studied sites. We have also observed significantly different metal distribution patterns among different pools, exhibiting element-specific biogeochemical cycling mechanisms in the oceanic surface water.