Large Fluxes of Dissolved Aluminum Exported from the China’s Coast to the Ocean

21 October 2015

In the Eastern China Sea, the continental shelf serves as an important source of dissolved aluminum (Al) for the overlaying waters via resuspension of sediments and benthic fluxes. This was demonstrated by researchers from GEOTERACES who identified cross-shelf transport in the subsurface water over the Eastern China Sea. The dissolved aluminum export from the 100 meter isobath is 1.67 x 1010 grams per yr.

Thanks to the Kuroshio current, more than half of this Al is transported northward within the region enclosed by the 100 m and 200 m isobaths to the Japan Sea/East Sea. The remaining flux is transported out of the shelf across the 200 meter isobath. This highlights the importance of coastal processes and subsurface cross-shelf transport as a source of dissolved trace elements to the open ocean.

The researchers used simulation tools from the Massachusetts Institute of Technology general circulation model (MITgcm) to calculate cross-shelf fluxes of water and dissolved Al. The calculated cross-shelf fluxes of Al at the subsurface layer indicate that the Eastern China Sea is highly efficient in pumping Al-rich coastal waters northward to the Japan Sea/East Sea and/or eastward into the western Pacific. Researchers also identified an important role of the monsoon, with a change from northeasterly wind to southwesterly wind in spring, on the cross-shelf transport of Al by use of numerical tracer experiments.

Reference:

Ren, J.-L., Xuan, J.-L., Wang, Z.-W., Huang, D., & Zhang, J. (2015). Cross-shelf transport of terrestrial Al enhanced by the transition of northeasterly to southwesterly monsoon wind over the East China Sea. Journal of Geophysical Research: Oceans, 120(7), 5054–5073. doi:10.1002/2014JC010655.