The distributions of dimethylsulfide (DMS) as well as particulate and dissolved fractions of dimethylsulfoniopropionate (DMSPp and DMSPd) were examined in the sea-surface microlayer (SML) and corresponding subsurface water (SSL) of the Yellow Sea,China during April 2006.Average DMS concentrations in the SML and SSL were 4.86 and 5.35 nM,respectively.The enrichment factors (EFs) of DMS in the SML ranged from 0.47 to 2.24 with a mean of 0.98.In contrast,DMSPd and DMSPp appeared to be enriched in the SML with average EFs of 1.75 and 1.36,respectively,presumably due to the higher levels of chlorophyll a in the SML.Our results showed that both DMS and DMSPp concentrations were significantly correlated with chlorophyll a concentrations in the SML and SSL,respectively,suggesting that phytoplankton biomass might play an important role in controlling the distributions of DMS(P) in the study area.Interestingly,we observed higher production rates and consumption rates of DMS in the SML relative to SSL and the DMS production rates were closely correlated with the DMSPd concentrations.Microlayer enrichment of chlorophyll a and enhanced DMS production rates in the SML imply that the surface microlayer has a greater biological activity relative to the underlying water.Moreover,we found a consistent correlation between the microlayer and subsurface water concentrations of DMS,DMSP and chlorophyll a,demonstrating that the biogenic materials in the SML come primarily from the bulk water.In addition,our study showed that the major sink of DMS in the SML was escape into the atmosphere,which greatly exceeded its bacterial consumption.