Distribution of dimethylsulfide and dimethylsulfoniopropionate in the surface microlayer and subsurface water of the Yellow Sea, China during spring

The concentrations of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in the surface microlayer and subsurface water were measured at 21 grid stations and one anchor station in the Yellow Sea, China in March 2005. The average concentrations of DMS and DMSP of dissolved (DMSPd) and particulate (DMSPp) forms were, respectively, 2.31 (1.20-4.54), 6.04 (2.13-9.48) and 7.98 (4.89-13.50) nM in the subsurface water, and those in the microlayer water were 2.26 (0.99-5.14), 9.10 (5.65-13.10) and 9.31 (4.08-15.64) nM. Among the sulfur components investigated, only DMSPd was found to be enriched in the microlayer with an average enrichment factor of 1.70. The concentrations of DMS, DMSPd and DMSPp in the microlayer were closely correlated with those in the corresponding subsurface water, implying that there was a strong exchange effect between the microlayer and subsurface water. The concentrations of DMS were positively correlated with the levels of chlorophyll a in the microlayer as well as in the subsurface water. The chlorophyll a-normalized DMS, DMSPd and DMSPp concentrations were 2.92 (1.47-5.72), 9.63 (2.07-27.88) and 13.10 (3.81-34.60) mmol g− 1 in the subsurface water, and 2.91 (0.77-5.24), 15.86 (1.22-32.34) and 15.95 (2.75-40.10) mmol g− 1 in the microlayer, respectively. A preliminary estimate for average flux of DMS from the Yellow Sea to the atmosphere was 3.14 μmol m− 2 day− 1.