Abstract. The Yellow Sea, surrounded by East China and the Korea Peninsula, is a potentially important receptor for anthropogenic mercury (Hg) emissions from East Asia. However, there is little documentation about the distribution and cycle of Hg in this marine system. During the cruise covering the Yellow Sea in July 2010, gaseous elemental mercury (GEM or Hg(0)) in the atmosphere, total Hg (THg), reactive Hg (RHg) and dissolved gaseous mercury (DGM, largely Hg(0)) in the waters were measured aboard the R/V Kexue III. The mean (±SD) concentration of GEM over the entire cruise was 2.61 ± 0.50 ng m −3 (range: 1.68 to 4.34 ng m −3 ), which were generally higher than other open oceans. The spatial distribution of GEM generally reflected a clear gradient with high levels near the coast of East China and low levels in open waters, suggesting the significant atmospheric Hg outflow from East China. The mean concentration of THg in the surface waters was 1.69 ± 0.35 ng l −1 and the RHg accounted for a considerable fraction of THg (RHg: 1.08 ± 0.28 ng l −1 , %RHg/THg = 63.9%). The mean concentration of DGM in the surface waters was 63.9 ± 13.7 pg l −1 and always suggested the supersaturation of Hg(0) in the surface waters with respect to Hg(0) in the atmosphere (the degree of saturation: 7.8 ± 2.3 with a range of 3.6-14.0). The mean Hg(0) flux at the air-sea interface was estimated to be 18.3 ± 11.8 ng m −2 h −1 based on a two-layer exchange model. The high wind speed and DGM levels induced the extremely high Hg(0) emission rates. Measurements at three stations showed no clear vertical patterns of DGM, RHg and THg in the water column. Overall, the elevated Hg levels in the Yellow Sea compared with other open oceans suggested that the human activity has influenced the oceanic Hg cycle downwind of East Asia.

The subtropical forested catchments are important for retention of atmospheric mercury deposition in southwest China. a r t i c l e i n f o a b s t r a c tForested catchments are an important part of the mercury (Hg) cycle and a link between the atmospheric and the aquatic environments. In this study, Hg input and output fluxes and its retention were investigated at subtropical forested catchments in southwest China. Significantly enhanced atmospheric Hg inputs were observed, and the contribution of litterfall Hg plays a more important role at these subtropical forested catchments. The ratios of Hg output fluxes from stream water to total input were 2.5% and 1.2% for LGS and TSP, which were markedly lower than those reported from Europe and North America. The current annual input Hg only accounted for 0.8 and 1.8 per mille to the Hg stored in the upper 90 cm of soil in LGS and TSP. These suggest that subtropical forested catchments are important for retention of atmospheric mercury deposition in southwest China.

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