Sample collection and analyses:Seasonal and spatial distributions of dimethylsulfide (DMS) were determined on aboard R/V Dong Fang Hong No. 2in the East China Sea (ECS) and the Yellow Sea (YS) during June-July, 2006 and January-February, 2007. The sampling stations are showed in Fig. 1. The summer cruise contained 35 stations along 8 transects, while 53 stations were made along 10 transects in the winter cruise, in which the horizontal distributions of DMS and chlorophyll a in the surface water were measured. Water samples were collected using 12 L Niskin bottles mounted to a Seabird 911 CTD. After collection, the concentrations of DMS in the samples were immediately analyzed on board, using a cryogenic purge-and-trap system, modified from Andreae and Barnard (1983).