Geophysical Research Letters

A unique seasonal pattern in dissolved elemental mercury in the South China Sea, a tropical and monsoon-dominated marginal sea

Authors


Corresponding authors: C. M. Tseng, Institute of Oceanography, National Taiwan University, PO Box 23-13, Taipei 106, Taiwan. (cmtseng99@ntu.edu.tw)

C. H. Lamborg, Woods Hole Oceanographic Institution, MS 51, Woods Hole, MA 02543, USA. (clamborg@whoi.edu)

Abstract

[1] A unique seasonal pattern in dissolved elemental mercury (DEM) was observed in the tropical monsoon-dominated South China Sea (SCS). The DEM concentration varied seasonally, with a high in summer of 160 ± 40 fM (net evasion 580 ± 120 pmol m−2 d−1, n = 4) and a low in winter of 60 ± 30 fM (net invasion −180 ± 110, n = 4) and showed a positive correlation with sea surface temperature (SST). The elevated DEM concentration in summer appears mainly abiologically driven. In winter, the SCS acts as a sink of atmosphere Hg0 as a result of low SST and high wind of the year, enhanced vertical mixing, and elevated atmospheric gaseous elemental mercury. Annually, the SCS serves as a source of Hg0 to the atmosphere of 300 ± 50 pmol m−2 d−1 (385 ± 64 kmol Hg yr−1, ~2.6% of global emission in ~1% of global ocean area), suggesting high regional Hg pollution impacts from the surrounding Mainland (mostly China).

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