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11.
The biological processes have been proposed as climate variability contributors. Dimethylsulfide (DMS) is the main biogenic sulfur compound in the atmosphere; it is mainly produced by the marine biosphere and plays an important role in the atmospheric sulfur cycle. Currently it is accepted that terrestrial biota not only adapts to environmental conditions but also influences them through regulations of the chemical composition of the atmosphere. In the present study we used a wavelet method to investigate the relationship between DMS, Low cloud cover (LCC), Ultraviolet Radiation A (UVA), Total Solar Irradiance (TSI) and Sea Surface Temperature (SST) in the so called pristine zone of the Southern Hemisphere. We found that the series analyzed have different periodicities which can be associated with large scale climatic phenomena such as El Niño (ENSO) or the Quasi-Biennial Oscillation (QBO), and/or to solar activity. Our results show an intermittent but sustained DMS-SST correlation and a DMSUVA anti correlation; but DMS-TSI and DMS-LCC show nonlinear relationships. The time-span of the series allow us to study only periodicities shorter than 11 years, then we limit our analysis to the possibility that solar radiation influences the Earth climate in periods shorter than the 11-year solar cycle. Our results also suggest a positive feedback interaction between DMS and solar radiation. 相似文献
12.
Mireille Lefvre Alain Vzina Maurice Levasseur John W. H. Dacey 《Deep Sea Research Part I: Oceanographic Research Papers》2002,49(12)
Dimethylsulfide (DMS) is a volatile sulfur compound produced by the marine biota. The flux of DMS to the atmosphere may act on climate via aerosol formation. It is therefore important to improve our understanding of the processes that regulate sea surface DMS concentrations for eventual inclusion into climate models. In order to simulate the dynamics of DMS concentrations in the mixed layer, a model of DMS production was developed and calibrated against a 1 year time-series of DMS and DMSP (dissolved and particulate) data collected in the Sargasso Sea at Hydrostation ‘S’. The model reproduces the observed divergence between the seasonal cycles of particulate DMSP, the DMS precursor produced by algae, and DMS produced through the microbial loop from the cleavage of dissolved DMSP. DMSPp (particulate) reaches its maximum in the spring whereas DMSPd (dissolved) and DMS reach maximum concentrations in summer. Several parameters had to vary seasonally and with depth in order to reproduce the data, pointing out the importance of physiological and structural changes in the plankton food web. These parameters include the intracellular S(DMSp):N ratio, the C:Chl ratio and the sinking rates of phytoplankton and detritus. For the Sargasso Sea, variations in the solar zenithal angle, which co-vary with the seasonal variations in the depth of the mixed layer, proved to be a convenient signal to drive the seasonal variation in the structure and dynamics of the plankton. Variations of the temperature and photosynthetically active radiation also help to reproduce the short-term variability of the annual S cycle. Results from a sensitivity analysis show that variations in DMSPp are dependent mostly on parameters controlling phytoplankton biomass, whereas DMS is dependent mostly on variables controlling phytoplankton productivity. 相似文献
13.
A.J. Gabric P.A. Matrai R.P. Kiene R. Cropp J.W.H. Dacey G.R. DiTullio R.G. Najjar R. Sim D.A. Toole D.A. delValle D. Slezak 《Deep Sea Research Part II: Topical Studies in Oceanography》2008,55(10-13):1505
The major source of reduced sulfur in the remote marine atmosphere is the biogenic compound dimethylsulfide (DMS), which is ubiquitous in the world's oceans and released through food web interactions. Relevant fluxes and concentrations of DMS, its phytoplankton-produced precursor, dimethylsulfoniopropionate (DMSP) and related parameters were measured during an intensive Lagrangian field study in two mesoscale eddies in the Sargasso Sea during July–August 2004, a period characterized by high mixed-layer DMS and low chlorophyll—the so-called ‘DMS summer paradox’. We used a 1-D vertically variable DMS production model forced with output from a 1-D vertical mixing model to evaluate the extent to which the simulated vertical structure in DMS and DMSP was consistent with changes expected from field-determined rate measurements of individual processes, such as photolysis, microbial DMS and dissolved DMSP turnover, and air–sea gas exchange. Model numerical experiments and related parametric sensitivity analyses suggested that the vertical structure of the DMS profile in the upper 60 m was determined mainly by the interplay of the two depth-variable processes—vertical mixing and photolysis—and less by biological consumption of DMS. A key finding from the model calibration was the need to increase the DMS(P) algal exudation rate constant, which includes the effects of cell rupture due to grazing and cell lysis, to significantly higher values than previously used in other regions. This was consistent with the small algal cell size and therefore high surface area-to-volume ratio of the dominant DMSP-producing group—the picoeukaryotes. 相似文献
14.
Temporal and spatial variations of dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) in the East China Sea and the Yellow Sea 总被引：5，自引：0，他引：5
Temporal and spatial distributions of dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) were determined in the East China Sea and the Yellow Sea during June-July, 2006 and January-February, 2007. The concentrations of DMS and total DMSP in surface water in the study area were 5.64 (1.79-12.24) and 28.25 (13.98-44.93) nmol L−1 in summer, and were 1.79 (1.02-3.51) and 11.01 (6.90-17.98) nmol L−1 in winter, respectively. The distributions of DMS and DMSP in the study area were obviously influenced by the Yangtze River effluent and the Kuroshio water. Even under highly variable hydrographic conditions, a significant relationship was observed between DMS and chlorophyll a concentrations in summer as well as in winter, suggesting that phytoplankton biomass might play an important role in controlling DMS distribution in the study area. The summer ratios of DMS/chlorophyll a and DMSP/chlorophyll a were approximately twofold higher than winter values, corresponding with the temporal variation in phytoplankton community structure between summer and winter. The sea-to-air fluxes of DMS were estimated to be 5.32 and 11.92 μmol m−2 d−1 using the equations of Liss and Merlivat (1986) and Wanninkhof (1992), respectively. 相似文献
15.
The distributions of dimethylsulfide (DMS) and its precursor, dimethylsulfoniopropionate (DMSP), were examined in the surface microlayer and corresponding subsurface water of the Yellow Sea, China, in April 2006. The average concentrations of DMS and DMSP of dissolved (DMSPd) and particulate (DMSPp) forms were 5.42 (1.78–12.75), 9.22 (2.85–19.73) and 17.50 (4.33–36.09) nmol L−1 in the subsurface water, and those in the surface microlayer were 4.92 (1.69–10.66), 17.08 (3.13–38.82) and 22.54 (4.85–47.24) nmol L−1, respectively. The enrichment factor (EF) of DMS in the microlayer ranged from 0.47 to 2.24 with a mean of 0.98. In contrast, DMSPd and DMSPp appeared to be enriched in the microlayer with average EFs of 1.98 and 1.39, respectively. A close correlation of integrated DMS, DMSPp and chlorophyll a concentrations for compiled data from all stations in the microlayer and the subsurface water indicated that phytoplankton biomass might play an important role in controlling the distributions of biogenic sulfurs in the study area. Moreover, a statistically significant relationship was found between the microlayer concentrations of DMS, DMSP and chlorophyll a and their subsurface water concentrations, suggesting a close linkage between these two water compartments. Interestingly, we observed higher biological production rates and consumption rates of DMS in the microlayer relative to the subsurface water. Furthermore, the DMS production rates were closely correlated both with DMSPd and chlorophyll a concentrations. Our study showed that the major sink of DMS in microlayer was escape into the atmosphere, which greatly exceeded its bacterial consumption. A preliminary estimate for average flux of DMS from the Yellow Sea to the atmosphere was 6.41 μmol m−2 d−1 during spring. 相似文献
16.
胶州湾及青岛近海微表层与次表层中二甲基硫(DMS)与二甲巯基丙酸(DMSP)的浓度分布 总被引：3，自引：0，他引：3
以胶州湾及青岛近海为研究区域,利用吹扫-捕集气相色谱法研究了二甲基硫(DMS)和二甲巯基丙酸(DMSP,分为溶解态DMSPd和颗粒态DMSPp)在微表层与次表层中的浓度以及它们在微表层中的富集行为。结果表明,DMS、DMSPd和DMSPp在微表层中的浓度高于次表层,它们在微表层中的富集因子分别为1.17、1.84和1.51。研究发现,DMS及DMSPp浓度与叶绿素a(Chl-a)浓度有很好的相关性,但它们的周日变化与Chl-a并不完全同步。DMS/Chl-a和DMSPp/Chl-a的比值在次表层和微表层分别为4.35、13.47mmol/g和3.99、15.88mmol/g。胶州湾及青岛近海生态环境受人为活动干扰严重,使本海域DMS含量较高,从而贡献出较大的DMS海-气通量。 相似文献
17.
The distributions of DMS and its precursor dimethylsulfoniopropionate, in both dissolved (DMSPd) and particulate fractions (DMSPp) were determined in the seasurface 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 concentrations 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 microlayer 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 DMSPp/chlorophyll 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/(m2·d), which highlights the effects of human impacts on DMS emission. 相似文献
18.
N. Mthalopoulos B. C. Nguyen C. Boissard J. M. Campin J. P. Putaud S. Belviso I. Barnes K. H. Becker 《Journal of Atmospheric Chemistry》1992,14(1-4):459-477
Measurements of atmospheric dimethylsulfide (DMS) and its oxidation products, sulfur dioxide (SO2), methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO4
2-) were monitored during the period June 9–26, 1989 at a coastal site in Brittany. As indicated by the radon (Rn-222) activities and the high concentrations of NOx the air masses, for most of the experiment, were continental in origin. The observed concentrations range from 1.9 to 65 nmol/m3 for DMS (n=157), 0.6 to 94.2 nmol/m3 for SO2 (n=50), 0.6 to 11.6 nmol/m3 for MSA (n=44) and 42 to 350 nmol/m3 for nss-SO4
2- (n=44). Aitken nuclei reached values as high as 4.5 × 105 particles/m3. When continental conditions predominated, the measured SO2 concentrations were lower than those expected from a consideration of the observed DMS concentrations and the existence of SO2 background of the continental air masses. Similarly, compared to the MSA/DMS ratio in the marine atmosphere, higher concentrations of MSA were observed than those expected from the measured levels of DMS. The presence of enhanced levels of MSA was also endorsed by the observation that the measured mean MSA/nss-SO4
2- ratio of 6±3% was similar to the mean value of 6.9% observed in the marine atmosphere. These above observations are in line with recent laboratory findings by Barnes et al. (1988), which show an increase of the MSA/DMS yield with a simultaneous decrease of the SO2/DMS yield in the presence of NOx. 相似文献
19.
Shipboard measurements of atmospheric dimethylsulfide and hydrogen sulfide in the Caribbean and Gulf of Mexico 总被引：1，自引：0，他引：1
Simultaneous shipboard measurements of atmospheric dimethylsulfide and hydrogen sulfide were made on three cruises in the Gulf of Mexico and the Caribbean. The cruise tracks include both oligotrophic and coastal waters and the air masses sampled include both remote marine air and air masses heavily influenced by terrestrial or coastal inputs. Using samples from two north-south Caribbean transects which are thought to represent remote subtropical Atlantic air, mean concentrations of DMS and H2S were found to be 57 pptv (74 ng S m-3, =29 pptv, n=48) and 8.5 pptv (11 ng S m-3, =5.3 pptv, n=36), respectively. The ranges of measured concentrations for all samples were 0–800 pptv DMS and 0–260 pptv H2S. Elevated concentrations were found in coastal regions and over some shallow waters. Statistical analysis reveals slight nighttime maxima in the concentrations of both DMS and H2S in the remote marine atmosphere. The diurnal nature of the H2S data is only apparent after correcting the measurements for interference due to carbonyl sulfide. Calculations using the measured ratio of H2S to DMS in remote marine air suggest that the oxidation of H2S contributes only about 11% to the excess (non-seasalt) sulfate in the marine boundary layer. 相似文献
20.
The tendency of dimethylsulfide (DMS) to form complexes with heavy metal ions in aqueous solutions and the factors that influence
it have been investigated. Among five heavy metal ions examined (Cu2+, Cd2+, Zn2+, Pb2+ and Hg2+), only Hg2+ bound significantly with DMS in aqueous solutions in which Hg2+ concentration was increased to much higher levels than that of natural seawater. The complexation capacity of Hg2+ for DMS was influenced by pH and media. The affinity of Hg2+ for DMS was generally lower at high than at low pH, presumably due to the competition of hydroxide ion to form hydroxomercury
species. In different solutions, the affinity of Hg2+ for DMS followed the following sequence: ultra-purified water > 35‰ NaCl solution > seawater. It seems apparent that chloride
had a negative impact on the complexation of DMS by Hg2+, owing to the competition of chloride with DMS for complexing Hg2+. In addition, the affinity of Hg2+ for DMS in the bulk seawater appeared to be higher than that in the surface microlayer seawater. The tendency of Hg2+ to form complexes with DMS in aqueous solution can be reduced by the presence of 2 mM amino-acid such as glycine, alanine,
serine and cysteine, as these ligands give stable mercury complexes. However, the presence of 2 mM acetate in experimental
solutions had no significant effect on the complexation of Hg2+ with DMS, even though this ligand has a relatively strong complexing capacity for Hg2+. Although mercury ions appeared to have a strong affinity for DMS, the concentration of mercury in seawater is too low to
produce a great effect on the distribution of DMS in oceans. 相似文献