Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

[摘要] Dimethylsulphide (DMS) and dissolved and particulatedimethylsulfoniopropionate (DMSP_d, DMSP_p) were measured innear-surface waters along the Mauritanian coast, Northwest Africa, duringthe upwelling season in February 2008. DMS, DMSP_d and DMSP_psurface concentrations of up to 10 nmol L⁻¹, 15 nmol L⁻¹ and990 nmol L⁻¹, respectively, were measured. However, the DMS concentrationsmeasured are in the low range compared to other upwelling regions. Themaximum DMSP_p concentration is the highest reported from upwellingregions so far, which might indicate that the Mauritanian upwelling is a hotspot for DMSP. Within the phytoplankton groups, dinoflagellates wereidentified as important contributors to DMS concentrations, while otheralgae seemed to have only a minor or no influence on DMS and DMSPconcentrations. A pronounced switch from high DMSP to high DMSconcentrations was observed when the nitrogen to phosphorus ratio (N:P) wasbelow 7. The high DMS/DMSP ratios at N:P ratios <7 indicate that nitrogenlimitation presumably triggered a switch from DMSP to DMS independent of thespecies composition. Our results underline the importance of coastalupwelling regions as a local source for surface seawater sulphur.

[学科分类] 地球化学与岩石