Studies On Production Of Dimethylsulfide, Dimethylsulfoniopropionate And Acrylic Acid In Marine Algae

Dimethylsulfide (DMS) is the most abundant volatile biogenetic sulfur compoundin the ocean, which plays an important role in the global sulfur cycle.Dimethylsulfoniopropionate (DMSP) is the major precursor of DMS, which isproduced by a wide variety of marine algae. In this dissertation, we firstly focus onthe production of DMS, DMSP and AA in eight marine algae during the growth stagesby laboratory culture experiment. The ratios of DMS/AA and AA/(DMSP+AA) arealso analyzed during the growth cycle. Secondly, we choose the Qingdao surfacewater as the study area. During dark incubations, the concentrations of DMS, DMSPand AA were measured. We also investigated the influence of DMSP concentrationsand temperatures on the DMSP degradation in the microcosms experiment. Theresults are drawn as follows:1. Studies on DMS, DMSP and AA production of eight species in marine algae(1) On the whole, the DMSP concentrations per cell of eight marine algae areshown as follows: Gymnodinium sp.> Skeletonema costatum> Prorocentrumdonhaiense Lu> Coccolithophorid> Phaeodactylum tricornutum>Platymonas subcordiformis> Chaetoceros curvisetus. The ability to produceAA of these marine algae was as follows: Amphidiniumcarterae Hulburt>Prorocentrum donhaiense Lu> Platymonas subcordiformis>Coccolithophorid> Chaetoceros curvisetus> Phaeodactylum tricornutum>Gymnodinium sp. The algae cells produce the largest amount of DMS, DMSPand AA in the late exponential growth and senescent stage.(2) All the average ratios of DMS/AA in microalgae cultures were less than50%during the whole growth period. Ratios of DMS/AA in eight marine algaeincreased in the exponential growth stage and decrease in the senescent stage.(3) Ratios AA/(DMSP+AA) of the eight algae have similar variations in the partof the growth stage. The ratios of AA/(DMSP+AA) remain high values in thestationary phase and exhibit a strong decrease beforecell density reached the maximum. However, the ratios increased significantly during the stationaryphase.2. Studies on DMSP degradation and influence factors on the DMSP degradation(1) The net consumption rate of DMSP in surface water of Dagang was about27times of Shilaoren. The degradation of DMSP was inhibited by GBT.(2) The rates of DMSP degradation were directly related to the concentration ofDMSP in surface water sample. The higher the concentration of DMSP was，the higher the concentrations of the produced DMS and AA. The ratios ofAA/(DMSP+AA) also increased. The ratios of DMS/AA ranged from1%to7%.(3) Temperature had an influence on the DMSP degradation. We measured theconcentrations of DMS, DMSP and AA in different temperatures (4℃,20℃a nd30℃). The production rates of DMS and AA and the ratio of AA/(DMSP+AA) at30℃are apparently higher than the others.