Spatial and temporal variability of dissolved sulfur compounds in European estuaries

The spatial and temporal distribution of Dimethylsulfide (DMS),Dimethylsulfoniopropionate (DMSP) – its precursor –,Dimethylsulfoxyde (DMSO) – one of its oxidation products –Carbonyl sulfide (COS) and Carbonyl disulfide (CS₂) wereinvestigated during nine oceanographic cruises carried out in six majortidal European estuaries between July 1996 and May 1998. Low levels ofDMS were recorded (mean of 0.6 nM, standard deviation () 0.3 nM)during these 9 cruises. Positive correlations between DMS and salinitywere frequently observed, with the highest DMS concentrations in theplume of estuaries, which could be explained by change in phytoplanktonspeciation from estuarine to shelf waters. Strong correlation betweenDMSP and DMS was reported for most of the estuaries denoting a simpleconservative mixing of riverine and marine waters controlled by tide. Incontrast to DMS, significant levels of COS and CS₂ with meanconcentrations of 220 ± 150 (pM; pM =10^–12 M) and 25 ± 6 pM respectively wererecorded in four estuaries, indicating that estuaries could be asignificant source of these compounds.