Dimethylsulfide(DMS) measurements in the surface seawater of China eastern coastline were conducted during March 9—10, 1993 in Bohai Sea along the cruise from Dalian to Tianjin and during September 24—25, 1994 in Ye...Dimethylsulfide(DMS) measurements in the surface seawater of China eastern coastline were conducted during March 9—10, 1993 in Bohai Sea along the cruise from Dalian to Tianjin and during September 24—25, 1994 in Yellow Sea along the cruise from Shanghai to Qingdao. On the cruise in Bohai Sea DMS concentrations varied from 0.11 to 2.63 nmol/L with an average of 1.31 nmol/L, while DMS flux was estimated to be 0.85 μmol/(m 2·d) with the range of 0.04—3.12 μmol/(m 2·d). On the cruise in Yellow Sea DMS concentrations varied from 0.95 to 7.48 nmol/L with an average of 2.89 nmol/L, and DMS flux was estimated to be 7.94 μmol/(m 2·d) with the range of 0.11—18.88 μmol/(m 2·d). Variations in DMS concentrations along the latitude in Yellow Sea were observed larger than those along the longitude in Bohai Sea. DMS concentrations and fluxes had a similar spatial trend both in Bohai Sea and Yellow Sea with the correlation coefficients of 0.75 and 0.64, respectively.展开更多
The distributions of DMS and its precursor dimethylsulfoniopropionate, in both dissolved （DMSPd） and particulate fractions （DMSPp） were determined in the sea-surface microlayer and corresponding subsurface water o...The distributions of DMS and its precursor dimethylsulfoniopropionate, in both dissolved （DMSPd） and particulate fractions （DMSPp） were determined in the sea-surface microlayer and corresponding subsurface water of the Jiaozhou Bay, China and its adjacent area in May and August 2006. The concentrations of all these components showed a clear seasonal variation, with higher concen- trations occurring in summer. This can be mainly attributed to the higher phytoplankton biomass observed in summer. Simultaneously, the enrichment extents of DMSPd and DMSPp in the mi- crolayer also exhibited seasonal changes, with higher values in spring and lower ones in summer. Higher water temperature and stronger radiant intensity in summer can enhance their solubility and photochemical reaction in the microlayer water, reducing their enrichment factors （the ratio of concentration in the microlayer to that in the corresponding subsurface water）. A statistically significant relationship was found between the microlayer and subsurface water concentrations of DMS, DMSP and chlorophyll a, demonstrating that the biogenic materials in the microlayer come primarily from the underlying water. Moreover, our data show that the concentrations of DMSPp and DMS were significantly correlated with the levels of chlorophyll a, indicating that phytoplankton biomass might play an important role in controlling the distributions of biogenic sulfurs in the study area. The ratios of DMS/chlorophyll a and DMSPpchlorophyll a varied little from spring to summer, suggesting that there was no obvious change in the proportion of DMSP producers in the phytoplankton community. The mean sea-to-air flux of DMS from the study area was estimated to be 5.70 μmol/（m^2·d）, which highlights the effects of human impacts on DMS emission.展开更多
A sequential method for the determination of dimethyl sulfur compounds, including dimethylsulfide （DMS）, dimethylsulfonio- propionate （DMSP） and dimethylsulfoxide （DMSO）, in seawater samples has been developed. ...A sequential method for the determination of dimethyl sulfur compounds, including dimethylsulfide （DMS）, dimethylsulfonio- propionate （DMSP） and dimethylsulfoxide （DMSO）, in seawater samples has been developed. Detection limit of 2.5 pmol of DMS in 25 mL sample, corresponding to 0.10 nmol/L, was achieved. Recoveries for dimethyl sulfur compounds were in the range of 68.6- 78.3%. The relative standard deviations （R.S.D.s） for DMS, DMSP and DMSO determination were 3.0, 5.4 and 7.4%, respectively.展开更多
The production of dimethylsulfide （DMS） and dimethylsulfoniopropionate （DMSP） by marine microalgae was investigated to elucidate more on the role of marine phytoplankton in ocean-atmosphere interactions in the glo...The production of dimethylsulfide （DMS） and dimethylsulfoniopropionate （DMSP） by marine microalgae was investigated to elucidate more on the role of marine phytoplankton in ocean-atmosphere interactions in the global biogeochemical sulfur cycle.Axenic laboratory cultures of four marine microalgae–Isochrysis galbana 8701,Pavlova viridis,Platymonas sp.and Chlorella were tested for DMSP production and conversion into DMS.Among these four microalgae,Isochrysis galbana 8701 and Pavlova viridis are two species of Haptophyta,while Chlorella and Platymonas sp.belong to Chlorophyta.The results demonstrate that the four algae can produce various amounts of DMS（P）,and their DMS（P） production was species specific.With similar cell size,more DMS was released by Haptophyta than that by Chlorophyta.DMS and dissolved DMSP （DMSPd） concentrations in algal cultures varied significantly during their life cycles.The highest release of DMS appeared in the senescent period for all the four algae.Variations in DMSP concentrations were in strong compliance with variations in algal cell densities during the growing period.A highly significant correlation was observed between the DMS and DMSPd concentrations in algal cultures,and there was a time lag for the variation trend of the DMS concentrations as compared with that of the DMSPd.The consistency of variation patterns of DMS and DMSPd implies that the DMSPd produced by phytoplankton cells has a marked effect on the production of DMS.In the present study,the authors’ results specify the significant contribution of the marine phytoplankton to DMS（P） production and the importance of biological control of DMS concentrations in oceanic water.展开更多
Dimethylsulfide （DMS） is generally thought to be lost from the surface oceans by evasion into the atmosphere as well as consumption by microbe. However, photochemical process might be important in the removal of DMS...Dimethylsulfide （DMS） is generally thought to be lost from the surface oceans by evasion into the atmosphere as well as consumption by microbe. However, photochemical process might be important in the removal of DMS in the oceanic photic zone. A kinetic investigation into the photochemical oxidation of DMS in seawater was performed. The photo-oxidation rates of DMS were influenced by various factors including the medium, dissolved oxygen, photosensitizers, and heavy metal ions. The photo-oxidation rates of DMS were higher in seawater than in distilled water, presumably due to the effect of salinity existing in seawater. Three usual photosensitizers （humic acid, fulvic acid and anthroquinone）, especially in the presence of oxygen, were able to enhance the photo-oxidation rate of DMS, with the fastest rate observed with anthroquinone. Photo-oxidation of DMS followed first order reaction kinetics with the rate constant ranging from 2.5 × 10^-5 to 34.3 × 10^-5. Quantitative analysis showed that approximately 32% of the photochemically removed DMS was converted to dimethylsulfoxide. One of the important findings was that the presence of Hg^2 ＋ could markedly accelerate the photo-oxidation rate of DMS in seawater. The mechanism of mercuric catalysis for DMS photolysis was suggested according to the way of CTTM （ charge transfer to metal） of DMS - Hg^2＋ complex.展开更多
文摘Dimethylsulfide(DMS) measurements in the surface seawater of China eastern coastline were conducted during March 9—10, 1993 in Bohai Sea along the cruise from Dalian to Tianjin and during September 24—25, 1994 in Yellow Sea along the cruise from Shanghai to Qingdao. On the cruise in Bohai Sea DMS concentrations varied from 0.11 to 2.63 nmol/L with an average of 1.31 nmol/L, while DMS flux was estimated to be 0.85 μmol/(m 2·d) with the range of 0.04—3.12 μmol/(m 2·d). On the cruise in Yellow Sea DMS concentrations varied from 0.95 to 7.48 nmol/L with an average of 2.89 nmol/L, and DMS flux was estimated to be 7.94 μmol/(m 2·d) with the range of 0.11—18.88 μmol/(m 2·d). Variations in DMS concentrations along the latitude in Yellow Sea were observed larger than those along the longitude in Bohai Sea. DMS concentrations and fluxes had a similar spatial trend both in Bohai Sea and Yellow Sea with the correlation coefficients of 0.75 and 0.64, respectively.
基金The National Natural Science Foundation of China under contract Nos 40476034, 40525017 and 40490265 the Science and Technology Key Project of Shandong Province, China under contract No 2006GG2205024the Taishan Mountain Scholar Construction Engineering Special Fund of Shandong Province, China
文摘The distributions of DMS and its precursor dimethylsulfoniopropionate, in both dissolved （DMSPd） and particulate fractions （DMSPp） were determined in the sea-surface microlayer and corresponding subsurface water of the Jiaozhou Bay, China and its adjacent area in May and August 2006. The concentrations of all these components showed a clear seasonal variation, with higher concen- trations occurring in summer. This can be mainly attributed to the higher phytoplankton biomass observed in summer. Simultaneously, the enrichment extents of DMSPd and DMSPp in the mi- crolayer also exhibited seasonal changes, with higher values in spring and lower ones in summer. Higher water temperature and stronger radiant intensity in summer can enhance their solubility and photochemical reaction in the microlayer water, reducing their enrichment factors （the ratio of concentration in the microlayer to that in the corresponding subsurface water）. A statistically significant relationship was found between the microlayer and subsurface water concentrations of DMS, DMSP and chlorophyll a, demonstrating that the biogenic materials in the microlayer come primarily from the underlying water. Moreover, our data show that the concentrations of DMSPp and DMS were significantly correlated with the levels of chlorophyll a, indicating that phytoplankton biomass might play an important role in controlling the distributions of biogenic sulfurs in the study area. The ratios of DMS/chlorophyll a and DMSPpchlorophyll a varied little from spring to summer, suggesting that there was no obvious change in the proportion of DMSP producers in the phytoplankton community. The mean sea-to-air flux of DMS from the study area was estimated to be 5.70 μmol/（m^2·d）, which highlights the effects of human impacts on DMS emission.
文摘A sequential method for the determination of dimethyl sulfur compounds, including dimethylsulfide （DMS）, dimethylsulfonio- propionate （DMSP） and dimethylsulfoxide （DMSO）, in seawater samples has been developed. Detection limit of 2.5 pmol of DMS in 25 mL sample, corresponding to 0.10 nmol/L, was achieved. Recoveries for dimethyl sulfur compounds were in the range of 68.6- 78.3%. The relative standard deviations （R.S.D.s） for DMS, DMSP and DMSO determination were 3.0, 5.4 and 7.4%, respectively.
基金The National Natural Science Foundation of China under contract Nos 40525017 and 40476034the Changjiang Scholars Programme,Ministry of Education of China+1 种基金the Science and Technology Key Project of Shandong Province under contract No.2006GG2205024the "Taishan Scholar" Special Research Fund of Shandong Province,China
文摘The production of dimethylsulfide （DMS） and dimethylsulfoniopropionate （DMSP） by marine microalgae was investigated to elucidate more on the role of marine phytoplankton in ocean-atmosphere interactions in the global biogeochemical sulfur cycle.Axenic laboratory cultures of four marine microalgae–Isochrysis galbana 8701,Pavlova viridis,Platymonas sp.and Chlorella were tested for DMSP production and conversion into DMS.Among these four microalgae,Isochrysis galbana 8701 and Pavlova viridis are two species of Haptophyta,while Chlorella and Platymonas sp.belong to Chlorophyta.The results demonstrate that the four algae can produce various amounts of DMS（P）,and their DMS（P） production was species specific.With similar cell size,more DMS was released by Haptophyta than that by Chlorophyta.DMS and dissolved DMSP （DMSPd） concentrations in algal cultures varied significantly during their life cycles.The highest release of DMS appeared in the senescent period for all the four algae.Variations in DMSP concentrations were in strong compliance with variations in algal cell densities during the growing period.A highly significant correlation was observed between the DMS and DMSPd concentrations in algal cultures,and there was a time lag for the variation trend of the DMS concentrations as compared with that of the DMSPd.The consistency of variation patterns of DMS and DMSPd implies that the DMSPd produced by phytoplankton cells has a marked effect on the production of DMS.In the present study,the authors’ results specify the significant contribution of the marine phytoplankton to DMS（P） production and the importance of biological control of DMS concentrations in oceanic water.
基金We greatly acknowledge the support provided for this research by the National Natural Science Foundation of China under contract Nos 40476034,40525017 and 40490265We are also grateful for the support of Key Project of Ministry of Education,China under contract No.105105+1 种基金the Program for New Century Excellent Talents in University,Ministry of Education under contract No.NCET-04-0643Taishan Mountain Scholar Construction Engineering Special Fund of Shandong Province,China.
文摘Dimethylsulfide （DMS） is generally thought to be lost from the surface oceans by evasion into the atmosphere as well as consumption by microbe. However, photochemical process might be important in the removal of DMS in the oceanic photic zone. A kinetic investigation into the photochemical oxidation of DMS in seawater was performed. The photo-oxidation rates of DMS were influenced by various factors including the medium, dissolved oxygen, photosensitizers, and heavy metal ions. The photo-oxidation rates of DMS were higher in seawater than in distilled water, presumably due to the effect of salinity existing in seawater. Three usual photosensitizers （humic acid, fulvic acid and anthroquinone）, especially in the presence of oxygen, were able to enhance the photo-oxidation rate of DMS, with the fastest rate observed with anthroquinone. Photo-oxidation of DMS followed first order reaction kinetics with the rate constant ranging from 2.5 × 10^-5 to 34.3 × 10^-5. Quantitative analysis showed that approximately 32% of the photochemically removed DMS was converted to dimethylsulfoxide. One of the important findings was that the presence of Hg^2 ＋ could markedly accelerate the photo-oxidation rate of DMS in seawater. The mechanism of mercuric catalysis for DMS photolysis was suggested according to the way of CTTM （ charge transfer to metal） of DMS - Hg^2＋ complex.
