Determination of the diffusion constants of dimethylsulfide and dimethylsulfoniopropionate by diffusion-ordered nuclear magnetic resonance spectroscopy

Diffusion of small molecules influences sea-to-air transfer in the oceans as well as export or uptake from the water column by microorganisms. Direct quantification of diffusion therefore can better constrain the rates of these processes. The diffusion coefficients (D) for both dimethylsulfide (DMSP) and dimethylsulfoniopropionate (DMSP) were determined using diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY). Diffusion coefficients were measured across a temperature range (285-315 K, 12-42 degrees C) and were corrected for changes in the diffusion coefficient of water. DDMSP was determined in both artificial seawater (salinity 30.5) and in MilllQ water. Diffusion constants (0.929-2.22 x 10(-5) cm(2) s(-1) for DMS and 0.504-1.22 x 10(-5) cm(2) s(-1) for DMSP) were within the range predicted by various empirical models (0.72-2.12 x 10(-5) cm(2) s(-1) for DMS and 0.34-1.12 x 10(-5) cm(2) s(-1) for DMSP). Dpmsp was well-predicted by theoretical models such (Evans et al., 2013) and does not have a strong concentration, salinity, or pH dependence. Implications for diffusion of DMSP on cellular physiology are discussed.