Spatial variability of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in the southern Gulf of Mexico

Abstract

Environmental context Dimethylsulfide (DMS), the main biogenic sulfur compound in the atmosphere, is produced by the marine biosphere and plays an important role in the atmospheric sulfur cycle. This study recorded the spatial variability of DMS and dissolved and particulate dimethylsulfoniopropionate (DMSP) in the water column of the southern Gulf of Mexico. The results suggest that the spatial variability of DMS and DMSP is directly related to the hydrodynamics of the study area. Abstract The spatial variability of dimethylsulfide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd and DMSPp) was recorded in the southern Gulf of Mexico at three different depths (10, 30 and 60m) in January 2013. DMS and DMSP values were recorded through solid-phase microextraction coupled to gas chromatography. Average concentrations of DMS (2.8±1.5nM), DMSPd (1.7±0.9nM) and DMSPp (352±157nM) were significantly correlated with chlorophyll-a concentrations and the depth of the mixed layer. Vertical concentration profiles were similar, indicating a well-mixed water column with a thermocline at a depth of 50–100m. Average DMS sea-to-air flux was 5.0±1.7µmolm–2day–1. The greatest fluxes were recorded at the stations in the western region of the study area, owing to the combined effect of high DMS concentrations (3.7–7.21nM) and a high wind speed (4.4–6.8ms–1). The greatest concentrations were recorded at the stations nearest the coast. The distribution of DMS and DMSP was apparently related to the oceanic hydrodynamics.