Seasonal and spatial variations of dimethylsulfoxide (DMSO) in the East China Sea and the Yellow Sea

Seasonal and spatial distributions of dissolved and particulate dimethylsulfoxide (DMSOd, DMSOp) were measured in the East China Sea and the Yellow Sea during March-April 2011 and October-November 2011. The concentrations of DMSOd and DMSOp in the surface water were 20.6 (5.13-73.8) and 8.90 (3.75-29.6) nmol/L in spring, and 13.4 (4.17-42.7) and 8.18 (3.44-22.6) nmol/L in autumn, respectively. Both DMSOd and DMSOp concentrations revealed similar seasonal changes with higher values occurring in spring, mainly because of the higher phytoplankton biomass observed in spring. Moreover, the ratios of DMSOp/chlorophyll a also exhibited an apparent seasonal change with higher values in autumn (35.7 mmol/g) and lower values in spring (23.4 mmol/g), thereby corresponding with the seasonal variation in the proportion of DMSO producers in the phytoplankton community between spring and autumn. In addition, DMSOd and DMSOp concentrations in the surface seawater revealed obvious diurnal variations with the maxima appearing in the afternoon.