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Sample records for dimethylsulfide

  1. Transformations of dimethylsulfide.

    PubMed

    Kappler, Ulrike; Schäfer, Hendrik

    2014-01-01

    Dimethylsulfide (DMS) is a naturally occurring chemical that is part of the biogeochemical sulfur cycle and has been implicated in climate-relevant atmospheric processes. In addition, DMS occurs in soil environments as well as in food stuff as a flavor compound and it can also be associated with disease states such as halitosis. A major environmental source of DMS is the marine algal osmoprotectant dimethylsulfoniopropionate (DMSP). A variety of bacterial enzyme systems lead either to the production of DMS from DMSP or dimethylsulfoxide (DMSO) or its oxidation to, e.g., DMSO. The interconversion of DMS and DMSO is catalyzed by molybdenum-containing metalloenzymes that have been very well studied, and recently another enzyme system, an NADH-dependent, flavin-containing monooxygenase, that produces formaldehyde and methanethiol from DMS has also been described.DMS conversions are not limited to a specialized group of bacteria - evidence for DMS-based metabolism exists for heterotrophic, autotrophic and phototrophic bacteria and there is also evidence for the occurrence of this type of sulfur compound conversion in Archaea. PMID:25416398

  2. Henry's law constants for dimethylsulfide in freshwater and seawater

    NASA Technical Reports Server (NTRS)

    Dacey, J. W. H.; Wakeham, S. G.; Howes, B. L.

    1984-01-01

    Distilled water and several waters of varying salinity were subjected, over a 0-32 C temperature range, to measurements for Henry's law constants for dimethylsulfide. Values for distilled water and seawater of the solubility parameters A and C are obtained which support the concept that the concentration of dimethylsulfide in the atmosphere is far from equilibrium with seawater.

  3. Emission of dimethylsulfide from Weddell Sea leads

    NASA Astrophysics Data System (ADS)

    Zemmelink, H. J.; Houghton, L.; Dacey, J. W. H.; Worby, A. P.; Liss, P. S.

    2005-12-01

    The distribution of dimethylsulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) was examined in lead water in pack ice of the Weddell Sea. Samples were taken by pulling water into a syringe from a series of depths from 0.002 m to 4 m and deeper. Concentrations of DMS, DMSP and DMSO remained low throughout the water column relative to surface water, which was highly enriched. Concentrations of the major sulfur compounds increased by over an order of magnitude during periods with smooth surface water conditions. This increase coincided with a profound stratification of the water column, caused by a decrease in salinity of near surface water. We estimate that the DMS emission from leads and open water in Antarctic sea ice could contribute significantly to the yearly DMS flux from the Southern Ocean.

  4. Factors controlling dimethylsulfide emission from salt marshes

    NASA Technical Reports Server (NTRS)

    Dacey, John W. H.; Wakeham, S. G.; Howes, B. L.

    1985-01-01

    The factors that control the emission of methylated gases from salt marshes are being studied. Research focusses on dimethylsulfide (DMS) formation and the mechanism of DMS and CH4 emission to the atmosphere. The approach is to consider the plants as valves regulating the emission of methylated gases to the atmosphere with the goal of developing appropriate methods for emission measurement. In the case of CH4, the sediment is the source and transport to the atmosphere occurs primarily through the internal gas spaces in the plants. The source of DMS appears to be dimethyl sulfoniopropionate (DMSP) which may play a role in osmoregulation in plant tissues. Concentrations of DMSP in leaves are typically several-fold higher than in roots and rhizomes. Even so, the large below ground biomass of this plant means that 2/3 of the DMSP in the ecosystem is below ground on the aerial basis. Upon introduction to sediment water, DMSP rapidly decomposes to DMS and acrylic acid. The solubility of a gas (its equilibrium vapor pressure) is a fundamental aspect of gas exchange kinetics. The first comprehensive study was conducted of DMS solubility in freshwater and seawater. Data suggest that the Setchenow relation holds for H at intermediate salinities collected. These data support the concept that the concentration of DMS in the atmosphere is far from equilibrium with seawater.

  5. Impact of dimethylsulfide chemistry on sulfate over the Northern Hemisphere

    EPA Science Inventory

    Sulfate aerosol forms from the gas- and aqueous-phase oxidation of sulfur dioxide and is an important component of atmospheric aerosols. Dimethylsulfide (DMS) present in sea-water can be emitted into the atmosphere which can then react with atmospheric oxidants to produce sulfur ...

  6. Enhancement of dimethylsulfide production by anoxic stress in natural seawater

    NASA Astrophysics Data System (ADS)

    Omori, Yuko; Tanimoto, Hiroshi; Inomata, Satoshi; Wada, Shigeki; Thume, Kathleen; Pohnert, Georg

    2015-05-01

    Dimethylsulfide (DMS) is produced by phytoplankton in the ocean and plays an important role in biogeochemical cycles and climate system of the Earth. Previous field studies reported a possible relationship between DMS enhancement and anoxic condition, although the governing processes are still to be identified. Here we show the first direct evidence for the enhancement of DMS production by natural planktonic assemblages caused by anoxic stress. Under the anoxic condition, DMS production was considerably enhanced and DMS bacterial consumption was inhibited, resulting in an eightfold higher rate of gross DMS production than that under the oxic condition. Our results demonstrated that anoxic stress is one of important "environmental factors" in the marine DMS dynamics, suggesting the possible global importance due to ubiquity of anoxic conditions in the coastal oceans. This process would become more important in the future due to expansion of coastal hypoxic and anoxic zones by global warming.

  7. Dimethylsulfide air/sea gas transfer in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    De Bruyn, W. J.; Bell, T. G.; Marandino, C.; Saltzman, E. S.; Miller, S. D.; Law, C. S.; Smith, M. J.

    2012-12-01

    Air/sea dimethylsulfide (DMS) fluxes were measured by eddy correlation over the Southern Ocean (Feb/March 2012) aboard the R/V Tangaroa during the Surface Ocean Aerosol Production (SOAP) study. Atmospheric and seawater DMS were measured by atmospheric pressure chemical ionization mass spectrometry (API-CIMS). Seawater DMS was measured continuously from the ship underway system using a porous membrane equilibrator. The study included measurements inside and outside a dinoflagellate bloom of large areal extent, with seawater DMS levels ranging up to 20 nM. Horizontal wind speeds of up to 20 m/sec were encountered. Gas transfer coefficients were calculated from eddy covariance DMS flux measurements and the air-sea concentration gradient. This study represents a significant addition to the limited database of direct gas transfer measurements in the Southern Ocean.

  8. Purification and characterization of dimethylsulfide monooxygenase from Hyphomicrobium sulfonivorans.

    PubMed

    Boden, Rich; Borodina, Elena; Wood, Ann P; Kelly, Donovan P; Murrell, J Colin; Schäfer, Hendrik

    2011-03-01

    Dimethylsulfide (DMS) is a volatile organosulfur compound which has been implicated in the biogeochemical cycling of sulfur and in climate control. Microbial degradation is a major sink for DMS. DMS metabolism in some bacteria involves its oxidation by a DMS monooxygenase in the first step of the degradation pathway; however, this enzyme has remained uncharacterized until now. We have purified a DMS monooxygenase from Hyphomicrobium sulfonivorans, which was previously isolated from garden soil. The enzyme is a member of the flavin-linked monooxygenases of the luciferase family and is most closely related to nitrilotriacetate monooxygenases. It consists of two subunits: DmoA, a 53-kDa FMNH₂-dependent monooxygenase, and DmoB, a 19-kDa NAD(P)H-dependent flavin oxidoreductase. Enzyme kinetics were investigated with a range of substrates and inhibitors. The enzyme had a K(m) of 17.2 (± 0.48) μM for DMS (k(cat) = 5.45 s⁻¹) and a V(max) of 1.25 (± 0.01) μmol NADH oxidized min⁻¹ (mg protein⁻¹). It was inhibited by umbelliferone, 8-anilinonaphthalenesulfonate, a range of metal-chelating agents, and Hg²(+), Cd²(+), and Pb²(+) ions. The purified enzyme had no activity with the substrates of related enzymes, including alkanesulfonates, aldehydes, nitrilotriacetate, or dibenzothiophenesulfone. The gene encoding the 53-kDa enzyme subunit has been cloned and matched to the enzyme subunit by mass spectrometry. DMS monooxygenase represents a new class of FMNH₂-dependent monooxygenases, based on its specificity for dimethylsulfide and the molecular phylogeny of its predicted amino acid sequence. The gene encoding the large subunit of DMS monooxygenase is colocated with genes encoding putative flavin reductases, homologues of enzymes of inorganic and organic sulfur compound metabolism, and enzymes involved in riboflavin synthesis. PMID:21216999

  9. Mechanism of the Thermal Decomposition of Ethanethiol and Dimethylsulfide

    NASA Astrophysics Data System (ADS)

    Melhado, William Francis; Whitman, Jared Connor; Kong, Jessica; Anderson, Daniel Easton; Vasiliou, AnGayle (AJ)

    2016-06-01

    Combustion of organosulfur contaminants in petroleum-based fuels and biofuels produces sulfur oxides (SO_x). These pollutants are highly regulated by the EPA because they have been linked to poor respiratory health and negative environmental impacts. Therefore much effort has been made to remove sulfur compounds in petroleum-based fuels and biofuels. Currently desulfurization methods used in the fuel industry are costly and inefficient. Research of the thermal decomposition mechanisms of organosulfur species can be implemented via engineering simulations to modify existing refining technologies to design more efficient sulfur removal processes. We have used a resistively-heated SiC tubular reactor to study the thermal decomposition of ethanethiol (CH_3CH_2SH) and dimethylsulfide (CH_3SCH_3). The decomposition products are identified by two independent techniques: 118.2 nm VUV photoionization mass spectroscopy and infrared spectroscopy. The thermal cracking products for CH_3CH_2SH are CH_2CH_2, SH, and H_2S and the thermal cracking products from CH_3SCH_3 are CH_3S, CH_2S, and CH_3.

  10. Modelling the production of dimethylsulfide during a phytoplankton bloom

    NASA Astrophysics Data System (ADS)

    Gabric, Albert; Murray, Nicholas; Stone, Lewi; Kohl, Manfred

    1993-12-01

    Dimethylsulfide (DMS) is an important sulfur-containing atmospheric trace gas of marine biogenic origin. DMS emitted from the oceans may be a precursor of tropospheric aerosols and cloud condensation nuclei (CCN), thereby affecting the Earth's radiative balance and possibly constituting a negative feedback to global warming, although this hypothesis is still somewhat controversial. The revised conceptual model of the marine pelagic food web gives a central role to planktonic bacteria. Recent experiments have shown that consumption of dissolved DMS by microbial metabolism may be more important than atmospheric exchange in controlling its concentration in surface waters and hence its ventilation to the atmosphere. In this paper we investigate the effect of the marine food web on cycling of dissolved DMS in surface waters during a phytoplankton bloom episode. A nitrogen-based flow network simulation model has been used to analyze the relative importance of the various biological and chemical processes involved. The model predictions suggest that the concentration of DMS in marine surface waters is indeed governed by bacterial metabolism. Environmental factors that affect the bacterial compartment are thus likely to have a relatively large influence on dissolved DMS concentrations. The ecological succession is particularly sensitive to the ratio of phytoplankton to bacterial nutrient uptake rates as well the interaction between herbivore food chain and the microbial loop. Importantly for the design of field studies, the model predicts that peak DMS concentrations are achieved during the decline of the phytoplankton bloom with a typical time lag between peak DMS and peak phytoplankton biomass of 1 to 2 days. Significantly, the model predicts a relatively high DMS concentration persisting after the phytoplankton bloom due to excretion from large protozoa and zooplankton, which may be an additional explanation for the lack of correlation between DMS and chlorophyll a

  11. Marine microbial production of dimethylsulfide from dissolved dimethylsulfoniopropionate. Doctoral thesis

    SciTech Connect

    Ledyard, K.M.

    1993-02-01

    Dimethylsulfide (DMS) plays a central role in the transfer of sulfur from the ocean to the atmosphere, and ultimately to land. The most abundant volatile organosulfur compound in seawater, DMS is believed to account for the bulk of the sea-to-air biogenic sulfur flux. DMS has also been implicated as the major precursor of submicron-sized sulfate aerosol over the ocean. This aerosol acts as an effective site for cloud droplet condensation, suggesting a possibly important role for DMS in marine cloud formation. In the ocean, the precursor of DMS is presumed to be the zwitterionic sulfonium compound dimethylsulfoniopropionate (DMSP), a common osmoticum in certain classes of marine algae. While some algae can cleave DMSP intracellularly to form DMS, correlation of DMS concentrations with indicators of algal productivity on a local scale is poor. This thesis focuses on an alternative pathway of DMS formation: microbial cleavage of dissolved (extracellular) DMSP. In laboratory studies, bacteria able to cleave DMSP to form DMS were isolated from seawater by a DMSP enrichment technique, and the kinetics of DMSP uptake and DMS production were examined closely in pure cultures of a bacterial isolate from the Sargasso Sea. The isolate could grow with both DMSP and acrylic acid, one of the products of DMSP cleavage, as the sole source of carbon and energy, and the enzyme catalyzing DMSP cleavage appeared to be induced by both of these compounds. Kinetic parameters were estimated for DMSP uptake and cleavage by whole cells. Comparison of the 16S rRNA sequence of this isolate with that of known eubacteria showed that it was most closely related to Erythrobacter longus, an aerobic, bacteriochlorophyll-containing member of the alpha proteobacteria.

  12. Physiological Ecology of Dimethylsulfoniopropionate (DMSP) and Dimethylsulfide (DMS) Production by Phytoplankton

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The main objectives of the previously funded work were: (1) to determine the rates of DMSP and DMS production as a function of phytoplankton growth rate; (2) to determine the light dependence (quantity and quality) of DiMethylSulfonioPropionate (DMSP) and DiMethylSulfide (DMS) production by phytoplankton; and (3) to study intraspecific differences in DMSP and DMS production by phytoplankton.

  13. A method for sampling dimethylsulfide in polluted and remote marine atmospheres

    NASA Astrophysics Data System (ADS)

    Davison, Brian M.; Allen, Andrew G.

    Methods have been developed for the measurement of atmospheric dimethylsulfide in both polluted and clean marine environments, avoiding Sampling losses due to reactions with atmospheric oxidants. Preconcentration of DMS on Molecular Sieve 5A was followed by analysis using gas chromatography with flame photometric detection. Prolonged contact of polluted air samples with a potassium iodide-based solution resulted in total oxidant destruction. Dimethylsulfide was measured over the Atlantic Ocean during a cruise between the U.K. and the Antarctic, between October 1992 and January 1993. In equatorial regions (30° N-30° S) the atmospheric DMS concentration ranged from 5 to 90 ng m -3 with an average of 30 ng m -3 In the polar waters and regions south of the Falkland Islands concentrations from 5 to 1050 ng m -3 were observed with a mean concentration of 120 ng m -3

  14. Vertical distribution of dimethylsulfide, sulfur dioxide, aerosol ions, and radon over the northeast Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Andreae, M. O.; Berresheim, H.; Andreae, T. W.; Kritz, M. A.; Bates, T. S.

    1988-01-01

    The vertical distributions, in temperate latitudes, of dimethylsulfide (DMS), SO2, radon, methanesulfonate (MSA), nonsea-salt sulfate (nss-sulfate), and aerosol Na(+), NH4(+), and NO(-) ions were determined in samples collected by an aircraft over the northeast Pacific Ocean during May 3-12, 1985. DMS was also determined in surface seawater. It was found that DMS concentrations, both in seawater and in the atmospheric boundary layer, were significantly lower than the values reported previously for subtropical and tropical regions, reflecting the seasonal variability in the temperate North Pacific. The vertical profiles of DMS, MSA, SO2, and nss-sulfate were found to be strongly dependent on the convective stability of the atmosphere and on air mass origin. Biogenic sulfur emissions could account for most of the sulfur budget in the boundary layer, while the long-range transport of continentally derived air masses was mainly responsible for the elevated levels of both SO2 and nss-sulfate in the free troposphere.

  15. Airborne sulfur trace species intercomparison campaign: Sulfur dioxide, dimethylsulfide, hydrogen sulfide, carbon disulfide, and carbonyl sulfide

    NASA Technical Reports Server (NTRS)

    Gregory, Gerald L.; Hoell, James M., Jr.; Davis, Douglas D.

    1991-01-01

    Results from an airborne intercomparison of techniques to measure tropospheric levels of sulfur trace gases are presented. The intercomparison was part of the NASA Global Tropospheric Experiment (GTE) and was conducted during the summer of 1989. The intercomparisons were conducted on the Wallops Electra aircraft during flights from Wallops Island, Virginia, and Natal, Brazil. Sulfur measurements intercompared included sulfur dioxide (SO2), dimethylsulfide (DMS), hydrogen sulfide (H2S), carbon disulfide (CS2), and carbonyl sulfide (OCS). Measurement techniques ranged from filter collection systems with post-flight analyses to mass spectrometer and gas chromatograph systems employing various methods for measuring and identifying the sulfur gases during flight. Sampling schedules for the techniques ranged from integrated collections over periods as long as 50 minutes to one- to three-minute samples every ten or fifteen minutes. Several of the techniques provided measurements of more than one sulfur gas. Instruments employing different detection principles were involved in each of the sulfur intercomparisons. Also included in the intercomparison measurement scenario were a host of supporting measurements (i.e., ozone, nitrogen oxides, carbon monoxide, total sulfur, aerosols, etc.) for purposes of: (1) interpreting results (i.e., correlation of any noted instrument disagreement with the chemical composition of the measurement environment); and (2) providing supporting chemical data to meet CITE-3 science objectives of studying ozone/sulfur photochemistry, diurnal cycles, etc. The results of the intercomparison study are briefly discussed.

  16. Air exposure of coral is a significant source of dimethylsulfide (DMS) to the atmosphere

    PubMed Central

    Hopkins, Frances E.; Bell, Thomas G.; Yang, Mingxi; Suggett, David J.; Steinke, Michael

    2016-01-01

    Corals are prolific producers of dimethylsulfoniopropionate (DMSP). High atmospheric concentrations of the DMSP breakdown product dimethylsulfide (DMS) have been linked to coral reefs during low tides. DMS is a potentially key sulfur source to the tropical atmosphere, but DMS emission from corals during tidal exposure is not well quantified. Here we show that gas phase DMS concentrations (DMSgas) increased by an order of magnitude when three Indo-Pacific corals were exposed to air in laboratory experiments. Upon re-submersion, an additional rapid rise in DMSgas was observed, reflecting increased production by the coral and/or dissolution of DMS-rich mucus formed by the coral during air exposure. Depletion in DMS following re-submersion was likely due to biologically-driven conversion of DMS to dimethylsulfoxide (DMSO). Fast Repetition Rate fluorometry showed downregulated photosynthesis during air exposure but rapid recovery upon re-submersion, suggesting that DMS enhances coral tolerance to oxidative stress during a process that can induce photoinhibition. We estimate that DMS emission from exposed coral reefs may be comparable in magnitude to emissions from other marine DMS hotspots. Coral DMS emission likely comprises a regular and significant source of sulfur to the tropical marine atmosphere, which is currently unrecognised in global DMS emission estimates and Earth System Models. PMID:27796323

  17. Biosynthesis of dimethylsulfide and dimethylpropiothetin by Hymenomonas carterae in relation to sulfur source and salinity variations

    SciTech Connect

    Vairavamurthy, A.; Andreae, M.O.; Iverson, R.L.

    1985-01-01

    The marine coccolithophoroid phytoplankton species Hymenomonas carterae (class Prymnesiophyceae) produces both dimethylpropiothetin (DMPT) and dimethylsulfide (DMS) in axenic cultures. The rate of DMS production is closely regulated by the cell; it remains independent of environmental sulfate concentration down to levels of 2.5% of the seawater value. Below this sulfate level, DMS production decreases with decreasing sulfate concentration, but significant amounts of DMS are released even under conditions of sulfate-limited growth. Hymenomonas carterae can grow on sulfite, thiosulfate, and cysteine as sulfur sources, but not on methionine. The rate of DMS output is similar for the different sulfur sources. Both the intracellular concentration of DMPT and the rate of output of DMS by H. carterae increase with increasing salinity of the medium. This increase is observed when either salt or sucrose is used to control the osmolarity of the growth medium. Variations in DMPT levels and DMS output were observed within hours after transferring cells to a medium of different osmotic pressure. These results suggest that DMPT plays an important role in osmoregulation by H. carterae.

  18. Dimethylsulfide gas transfer coefficients from algal blooms in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Bell, T. G.; De Bruyn, W.; Marandino, C. A.; Miller, S. D.; Law, C. S.; Smith, M. J.; Saltzman, E. S.

    2015-02-01

    Air-sea dimethylsulfide (DMS) fluxes and bulk air-sea gradients were measured over the Southern Ocean in February-March 2012 during the Surface Ocean Aerosol Production (SOAP) study. The cruise encountered three distinct phytoplankton bloom regions, consisting of two blooms with moderate DMS levels, and a high biomass, dinoflagellate-dominated bloom with high seawater DMS levels (> 15 nM). Gas transfer coefficients were considerably scattered at wind speeds above 5 m s-1. Bin averaging the data resulted in a linear relationship between wind speed and mean gas transfer velocity consistent with that previously observed. However, the wind-speed-binned gas transfer data distribution at all wind speeds is positively skewed. The flux and seawater DMS distributions were also positively skewed, which suggests that eddy covariance-derived gas transfer velocities are consistently influenced by additional, log-normal noise. A flux footprint analysis was conducted during a transect into the prevailing wind and through elevated DMS levels in the dinoflagellate bloom. Accounting for the temporal/spatial separation between flux and seawater concentration significantly reduces the scatter in computed transfer velocity. The SOAP gas transfer velocity data show no obvious modification of the gas transfer-wind speed relationship by biological activity or waves. This study highlights the challenges associated with eddy covariance gas transfer measurements in biologically active and heterogeneous bloom environments.

  19. Marine microbial production of dimethylsulfide from dissolved dimethylsulfoniopropionate. Ph. D. Thesis

    SciTech Connect

    Ledyard, K.M.

    1993-02-01

    Dimethylsulfide (DMS) plays a central role in the transfer of sulfur from the ocean to the atmosphere and ultimately to land. The most abundant volatile organosulfur compound in seawater, DMS is believed to account for the bulk of the sea-to-air biogenic sulfur flux. DMS has also been implicated as the major precursor of submicron-sized sulfate aerosol over the ocean. This aerosol acts as an effective site for cloud droplet condensation suggesting a possibly important role for DMS in marine cloud formation. In the ocean, the precursor of DMS is presumed to be the zwitterionic sulfonium compound dimethylsulfoniopropionate (DMSP), a common osmoticum in certain classes of marine algae. While some algae can cleave DMSP intracellularly to form DMS, correlation of DMS concentrations with indicators of algal productivity on a local scale is poor. This thesis focuses on an alternative pathway of DMS formation: microbial cleavage of dissolved (extracellular) DMSP. In laboratory studies, bacteria able to cleave DMSP to form DMS were isolated from seawater by a DMSP enrichment technique, and the kinetics of DMSP uptake and DMS production were examined closely in pure cultures of a bacterial isolate from the Sargasso Sea. The isolate could grow with both DMSP and acrylic acid, one of the products of DMSP cleavage, as the sole source of carbon and energy, and the enzyme catalyzing DMSP cleavage appeared to be induced by both of these compounds. Kinetic parameters were estimated for DMSP uptake and cleavage by whole cells. Comparison of the 16S rRNA sequence of this isolate with that of known eubacteria showed that it was most closely related to Erythrobacter longus, an aerobic, bacteriochlorophyll-containing member of the alpha proteobacteria.

  20. Weak response of oceanic dimethylsulfide to upper mixing shoaling induced by global warming.

    PubMed

    Vallina, S M; Simó, R; Manizza, M

    2007-10-01

    The solar radiation dose in the oceanic upper mixed layer (SRD) has recently been identified as the main climatic force driving global dimethylsulfide (DMS) dynamics and seasonality. Because DMS is suggested to exert a cooling effect on the earth radiative budget through its involvement in the formation and optical properties of tropospheric clouds over the ocean, a positive relationship between DMS and the SRD supports the occurrence of a negative feedback between the oceanic biosphere and climate, as postulated 20 years ago. Such a natural feedback might partly counteract anthropogenic global warming through a shoaling of the mixed layer depth (MLD) and a consequent increase of the SRD and DMS concentrations and emission. By applying two globally derived DMS diagnostic models to global fields of MLD and chlorophyll simulated with an Ocean General Circulation Model coupled to a biogeochemistry model for a 50% increase of atmospheric CO(2) and an unperturbed control run, we have estimated the response of the DMS-producing pelagic ocean to global warming. Our results show a net global increase in surface DMS concentrations, especially in summer. This increase, however, is so weak (globally 1.2%) that it can hardly be relevant as compared with the radiative forcing of the increase of greenhouse gases. This contrasts with the seasonal variability of DMS (1000-2000% summer-to-winter ratio). We suggest that the "plankton-DMS-clouds-earth albedo feedback" hypothesis is less strong a long-term thermostatic system than a seasonal mechanism that contributes to regulate the solar radiation doses reaching the earth's biosphere.

  1. Weak response of oceanic dimethylsulfide to upper mixing shoaling induced by global warming.

    PubMed

    Vallina, S M; Simó, R; Manizza, M

    2007-10-01

    The solar radiation dose in the oceanic upper mixed layer (SRD) has recently been identified as the main climatic force driving global dimethylsulfide (DMS) dynamics and seasonality. Because DMS is suggested to exert a cooling effect on the earth radiative budget through its involvement in the formation and optical properties of tropospheric clouds over the ocean, a positive relationship between DMS and the SRD supports the occurrence of a negative feedback between the oceanic biosphere and climate, as postulated 20 years ago. Such a natural feedback might partly counteract anthropogenic global warming through a shoaling of the mixed layer depth (MLD) and a consequent increase of the SRD and DMS concentrations and emission. By applying two globally derived DMS diagnostic models to global fields of MLD and chlorophyll simulated with an Ocean General Circulation Model coupled to a biogeochemistry model for a 50% increase of atmospheric CO(2) and an unperturbed control run, we have estimated the response of the DMS-producing pelagic ocean to global warming. Our results show a net global increase in surface DMS concentrations, especially in summer. This increase, however, is so weak (globally 1.2%) that it can hardly be relevant as compared with the radiative forcing of the increase of greenhouse gases. This contrasts with the seasonal variability of DMS (1000-2000% summer-to-winter ratio). We suggest that the "plankton-DMS-clouds-earth albedo feedback" hypothesis is less strong a long-term thermostatic system than a seasonal mechanism that contributes to regulate the solar radiation doses reaching the earth's biosphere. PMID:17901211

  2. Release of Dimethylsulfide from Dimethylsulfoniopropionate by Plant-Associated Salt Marsh Fungi

    PubMed Central

    Bacic, M. K.; Newell, S. Y.; Yoch, D. C.

    1998-01-01

    The range of types of microbes with dimethylsulfoniopropionate (DMSP) lyase capability (enzymatic release of dimethylsulfide [DMS] from DMSP) has recently been expanded from bacteria and eukaryotic algae to include fungi (a species of the genus Fusarium [M. K. Bacic and D. C. Yoch, Appl. Environ. Microbiol. 64:106–111, 1998]). Fungi (especially ascomycetes) are the predominant decomposers of shoots of smooth cordgrass, the principal grass of Atlantic salt marshes of the United States. Since the high rates of release of DMS from smooth cordgrass marshes have a temporal peak that coincides with peak shoot death, we hypothesized that cordgrass fungi were involved in this DMS release. We tested seven species of the known smooth cordgrass ascomycetes and discovered that six of them exhibited DMSP lyase activity. We also tested two species of ascomycetes from other DMSP-containing plants, and both were DMSP lyase competent. For comparison, we tested 11 species of ascomycetes and mitosporic fungi from halophytes that do not contain DMSP; of these 11, only 3 were positive for DMSP lyase. A third group tested, marine oomycotes (four species of the genera Halophytophthora and Pythium, mostly from mangroves), showed no DMSP lyase activity. Two of the strains of fungi found to be positive for DMSP lyase also exhibited uptake of DMS, an apparently rare combination of capabilities. In conclusion, a strong correlation exists between a fungal decomposer’s ability to catabolize DMSP via the DMSP lyase pathway and the host plant’s production of DMSP as a secondary product. PMID:16349548

  3. Effects of Harpacticus sp. (Harpacticoida, copepod) grazing on dimethylsulfoniopropionate and dimethylsulfide concentrations in seawater

    NASA Astrophysics Data System (ADS)

    Yu, Juan; Tian, Ji-Yuan; Yang, Gui-Peng

    2015-05-01

    We conducted 9 d and 24 h ingestion experiments to investigate the effects of copepod grazing on the concentrations of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) in seawater. Data from the 9 d trial showed that copepod Harpacticus sp. (Harpacticoida, copepod) grazing increased DMS (0-20%) and dissolved DMSP (DMSPd) (0-128%) apparently, accompanied by a significant reduction of particulate DMSP (DMSPp) in algal culture (0-30%). Ingestion rates (IRs) and pellet production rates (PPRs) of Harpacticus sp. varied with diet species (Platymonas subcordiformis (PS), Nitzschia closterium (NC), Skeletonema costatum (SC), Isochrysis galbana (IG), Prymnesium parvum (PP) or Heterosigma akashiwo (HA)), algal concentration, salinity and temperature. Harpacticus sp. fed on PP showed the lowest IRs (female/male, 0.72/0.53 × 104cells copepod- 1 h- 1) and PPRs (female/male, 0.75/0.5 pellets copepod- 1 h- 1), accompanied with the largest amounts of DMS and DMSPd,p (sum of DMSPd and DMSPp). IRs, PPRs, DMS and DMSPf (DMSP in fecal pellet) increased with the increase of food concentration and peaked at 25 × 104 cells mL- 1I. galbana. High salinity decreased IRs, PPRs, DMS and DMSPf and increased DMSPz (DMSP in copepod body) and DMSPd,p. IRs, PPRs, DMS and DMSPf increased with the increase of temperature from 15 to 25 °C, whereas DMSPz and DMSPd,p contents decreased. Pearson correlation analysis results showed that DMS concentrations presented positive relationships with IRs in algal concentration, salinity and temperature experiments (r = 0.746; P < 0.01). The contribution of DMSPz, DMSPf, DMS and DMSPd,p concentration to the total amounts (DMSPz + DMSPf + DMS + DMSPd,p) was 4-37%, 3-36%, 8-42% and 9-89%, respectively, indicating that DMSP was transferred to copepod tissue and fecal pellet via grazing. Our results are helpful for further understanding of the role of copepod grazing on DMS biogeochemical cycle.

  4. Short-term variability in the open ocean cycle of dimethylsulfide

    NASA Astrophysics Data System (ADS)

    Simó, Rafel; Pedrós-Alió, Carlos

    1999-12-01

    The marine biogeochemical cycle of dimethylsulfide (DMS), the main natural source of sulfur to the global atmosphere, was studied during a 2-week Lagrangian experiment in the subpolar North Atlantic, at 60°N 21°W. A bloom of coccolithopores, mostly of the species Emiliania huxleyi, dominated the phytoplankton assemblage over the first week. High surface concentrations of dimethylsulfoniopropionate (DMSP, 37-70 nM) were found along with moderate DMS concentrations (3-9 nM) during the entire experiment. Rates of biological DMSP consumption (8-51 nM d-1) and DMS production (1-14 nM d-1) and consumption (0-6 nM d-1) were measured in short-term dark incubations of surface seawater. Rates of DMSP biosynthesis (11-31 nM d-1) and DMS photochemical loss (1-10 nM d-1) were estimated by budgeting concentrations and transformation rates between Lagrangian samplings. Air-sea exchange rates for DMS (0.03-3 nM d-1) were calculated from surface concentrations, seawater temperature, and wind speed. All major processes involved in the DMS cycle showed significant short-term variability in coupling to the variability of solar radiation, wind speed, and mixing. Biotic and abiotic DMS turnover rates were of similar magnitude and very dynamic, with a prompt response to a rapidly changing physical environment. The rapid impact of meteorological forcing factors on DMS cycling provides the basis for a sulfur-mediated, short-term plankton/climate interaction.

  5. Production of dimethylsulfide and acrylic acid from dimethylsulfoniopropionate during growth of three marine microalgae

    NASA Astrophysics Data System (ADS)

    Liu, Chunying; Gao, Caixia; Zhang, Haibo; Chen, Shuo; Deng, Ping; Yue, Xin'an; Guo, Xiaoyi

    2014-11-01

    We measured the concentrations of dimethylsulfide (DMS), acrylic acid (AA), and dimethylsulfoniopropionate (DMSP) during growth of three microalgae: Prorocentrum micans, Gephyrocapsa oceanica, and Platymonas subcordiformis. The DMSP, AA, and DMS concentrations in culture media varied significantly among algal growth stages, with the highest concentrations in the late stationary growth stage or the senescent stage. In the stationary growth stage, the average DMSP concentration per cell in P. micans (0.066 5 pmol/cell) was 1.3 times that in G. oceanica (0.049 5 pmol/cell) and 20.2 times that in P. subcordiformis (0.003 29 pmol/cell). The average concentrations of AA were 0.044 6, 0.026 9, and 0.003 05 pmol/cell in P. micans, G. oceanica, and P. subcordiformi s, respectively, higher than the concentrations of DMS (0.272, 0.497, and 0.086 2 fmol/cell, respectively). There were significant positive correlations between cell density and AA, DMSP, and DMS concentrations. The ratios of DMS/AA and AA/(DMSP+AA) in the three algae differed significantly over the growth cycle. In all three microalgae, the DMS/AA ratios were less than 25% during the growth period, suggesting that the enzymatic cleavage pathway, which generates DMS, was not the main DMSP degradation pathway. The changes in the DMS/AA ratio indicated that there was a higher rate of enzymatic breakdown of DMSP in the early growth period and a lower rate during senescence. In all three microalgae, the AA/(DMSP+AA) ratio (degradation ratio of DMSP) decreased during the exponential growth phase, and then increased. The variations in these ratios can approximately indicate the cleavage mechanism of DMSP at different stages of algal growth.

  6. Production of dimethylsulfide and acrylic acid from dimethylsulfoniopropionate during growth of three marine microalgae

    NASA Astrophysics Data System (ADS)

    Liu, Chunying; Gao, Caixia; Zhang, Haibo; Chen, Shuo; Deng, Ping; Yue, Xin'an; Guo, Xiaoyi

    2014-07-01

    We measured the concentrations of dimethylsulfide (DMS), acrylic acid (AA), and dimethylsulfoniopropionate (DMSP) during growth of three microalgae: Prorocentrum micans, Gephyrocapsa oceanica, and Platymonas subcordiformis. The DMSP, AA, and DMS concentrations in culture media varied significantly among algal growth stages, with the highest concentrations in the late stationary growth stage or the senescent stage. In the stationary growth stage, the average DMSP concentration per cell in P. mican s (0.066 5 pmol/cell) was 1.3 times that in G. oceanica (0.049 5 pmol/cell) and 20.2 times that in P. subcordiformi s (0.003 29 pmol/cell). The average concentrations of AA were 0.044 6, 0.026 9, and 0.003 05 pmol/cell in P. micans, G. oceanica, and P. subcordiformi s, respectively, higher than the concentrations of DMS (0.272, 0.497, and 0.086 2 fmol/cell, respectively). There were significant positive correlations between cell density and AA, DMSP, and DMS concentrations. The ratios of DMS /AA and AA /(DMSP+AA) in the three algae differed significantly over the growth cycle. In all three microalgae, the DMS/AA ratios were less than 25% during the growth period, suggesting that the enzymatic cleavage pathway, which generates DMS, was not the main DMSP degradation pathway. The changes in the DMS/AA ratio indicated that there was a higher rate of enzymatic breakdown of DMSP in the early growth period and a lower rate during senescence. In all three microalgae, the AA /(DMSP+AA) ratio (degradation ratio of DMSP) decreased during the exponential growth phase, and then increased. The variations in these ratios can approximately indicate the cleavage mechanism of DMSP at different stages of algal growth.

  7. Diagnostic modeling of dimethylsulfide production in coastal water west of the Antarctic Peninsula

    NASA Technical Reports Server (NTRS)

    Hermann, Maria; Najjar, Raymond G.; Neeley, Aimee R.; Vila-Costa, Maria; Dacey, John W. H.; DiTullio, Giacomo, R.; Kieber, David J.; Kiene, Ronald P.; Matrai, Patricia A.; Simo, Rafel; Vernet, Maria

    2012-01-01

    The rate of gross biological dimethylsulfide (DMS) production at two coastal sites west of the Antarctic Peninsula, off Anvers Island, near Palmer Station, was estimated using a diagnostic approach that combined field measurements from 1 January 2006 through 1 March 2006 and a one-dimensional physical model of ocean mixing. The average DMS production rate in the upper water column (0-60 m) was estimated to be 3.1 +/- 0.6 nM/d at station B (closer to shore) and 2.7 +/- 0.6 nM/d1 at station E (further from shore). The estimated DMS replacement time was on the order of 1 d at both stations. DMS production was greater in the mixed layer than it was below the mixed layer. The average DMS production normalized to chlorophyll was 0.5 +/- nM/d)/(mg cubic m) at station B and 0.7 +/- 0.2 (nM/d)/(mg/cubic m3) at station E. When the diagnosed production rates were normalized to the observed concentrations of total dimethylsulfoniopropionate (DMSPt, the biogenic precursor of DMS), we found a remarkable similarity between our estimates at stations B and E (0.06 +/- 0.02 and 0.04 +/- 0.01 (nM DMS / d1)/(nM DMSP), respectively) and the results obtained in a previous study from a contrasting biogeochemical environment in the North Atlantic subtropical gyre (0.047 =/- 0.006 and 0.087 +/- 0.014 (nM DMS d1)/(nM DMSP) in a cyclonic and anticyclonic eddy, respectively).We propose that gross biological DMS production normalized to DMSPt might be relatively independent of the biogeochemical environment, and place our average estimate at 0.06 +/- 0.01 (nM DMS / d)/(nM DMSPt). The significance of this finding is that it can provide a means to use DMSPt measurements to extrapolate gross biological DMS production, which is extremely difficult to measure experimentally under realistic in situ conditions.

  8. Oxidation of dimethylsulfide to tetrathionate by Methylophaga thiooxidans sp. nov.: a new link in the sulfur cycle.

    PubMed

    Boden, Rich; Kelly, Donovan P; Murrell, J Colin; Schäfer, Hendrik

    2010-10-01

    A new pathway of dimethylsulfide (DMS) metabolism was identified in a novel species of Gammaproteobacteria, Methylophaga thiooxidans sp. nov., in which tetrathionate (S(4)O(6)(2-)) was the end-product of DMS oxidation. Inhibitor evidence indicated that DMS degradation was initiated by demethylation, catalysed by a corrinoid demethylase. Thiosulfate was an intermediate, which was oxidized to tetrathionate by a cytochrome-linked thiosulfate dehydrogenase. Thiosulfate oxidation was coupled to ATP synthesis, and M. thiooxidans could also use exogenous thiosulfate as an energy source during chemolithoheterotrophic growth on DMS or methanol. Cultures grown on a variety of substrates oxidized thiosulfate, indicating that thiosulfate oxidation was constitutive. The observations have relevance to interactions among sulfur-metabolizing bacteria in the marine environment. The production of tetrathionate from an organosulfur precursor is previously undocumented and represents a potential step in the biogeochemical sulfur cycle, providing a 'shunt' across the cycle.

  9. A mechanism for bacterial transformation of dimethylsulfide to dimethylsulfoxide: a missing link in the marine organic sulfur cycle.

    PubMed

    Lidbury, Ian; Kröber, Eileen; Zhang, Zhidong; Zhu, Yijun; Murrell, J Colin; Chen, Yin; Schäfer, Hendrik

    2016-09-01

    The volatile organosulfur compound, dimethylsulfide (DMS), plays an important role in climate regulation and global sulfur biogeochemical cycles. Microbial oxidation of DMS to dimethylsulfoxide (DMSO) represents a major sink of DMS in surface seawater, yet the underlying molecular mechanisms and key microbial taxa involved are not known. Here, we reveal that Ruegeria pomeroyi, a model marine heterotrophic bacterium, can oxidize DMS to DMSO using trimethylamine monooxygenase (Tmm). Purified Tmm oxidizes DMS to DMSO at a 1:1 ratio. Mutagenesis of the tmm gene in R. pomeroyi completely abolished DMS oxidation and subsequent DMSO formation. Expression of Tmm and DMS oxidation in R. pomeroyi is methylamine-dependent and regulated at the post-transcriptional level. Considering that Tmm is present in approximately 20% of bacterial cells inhabiting marine surface waters, particularly the marine Roseobacter clade and the SAR11 clade, our observations contribute to a mechanistic understanding of biological DMSO production in surface seawater. PMID:27114231

  10. Influence of salinity and nitrogen content on production of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) by Skeletonema costatum

    NASA Astrophysics Data System (ADS)

    Yang, Guipeng; Li, Chengxuan; Sun, Juan

    2011-03-01

    The effects of changing salinity and nitrogen limitation on dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) concentrations were investigated in batch cultures of coastal diatom Skeletonema costatum, an ecologically important species. Changes in salinity from 20-32 caused no measurable variation in cell growth or culture yield, but increased intracellular DMSP per cell by 30%. Nitrogen limitation caused up to a two-fold increase in total DMSP per cell and up to a three-fold increase in DMS per cell. These changes in DMSP and DMS per cell in the Skeletonema costatum cultures with nitrogen limitation and changing salinity were primarily attributed to the physiological functions of DMSP as an osmolyte and an antioxidant. The data obtained in this study indicated that nitrogen limitation and salinity may play an important role in climate feedback mechanisms involving biologically derived DMS.

  11. Biological and physical controls on dissolved dimethylsulfide over the north-eastern continental shelf of New Zealand

    NASA Astrophysics Data System (ADS)

    Walker, C. F.; Harvey, M. J.; Bury, S. J.; Chang, F. H.

    2000-08-01

    Data presented in this paper are part of an extensive investigation of the physics of cross-shelf water mass exchange in the north-east of New Zealand and its effect on biological processes. Levels of dissolved dimethylsulfide (DMS) were quantified in relation to physical processes and phytoplankton biomass. Measurements were made at three main sites over the north-east continental shelf of New Zealand's North Island during a current-driven upwelling event in late spring 1996 (October) and an oceanic surface water intrusion event in summer 1997 (January). DMS concentrations in the euphotic zone ranged between 0.4 and 12.9 nmol dm -3. Integrated water column DMS concentrations ranged from 33 to 173 μmol m -2 in late spring during the higher biomass (15-62 Chl- a mg m -2) month of October, and from 25 to 38 μmol m -2 in summer during the generally lower biomass (16-42 Chl- a mg m -2) month of January. We observed high levels of DMS in the surface waters at an Inner Shelf site in association with a Noctiluca scintillans bloom which is likely to have enhanced lysis of DMSP-producing algal cells during phagotrophy. Integrated DMS concentrations increased three-fold at a Mid Shelf site over a period of a week in conjunction with a doubling of algal biomass. A high correlation ( r2=0.911, significant <0.001) of integrated DMS and chlorophyll- a concentrations for compiled data from all stations indicated that chlorophyll- a biomass may be a reasonable predictor of DMS in this region, even under highly variable hydrographic conditions. Integrated bacterial production was inversely correlated to DMS production, indicating active bacterial consumption of DMS and/or its precursor.

  12. Characteristics of dimethylsulfide, ozone, aerosols, and cloud condensation nuclei in air masses over the northwestern Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nagao, Ippei; Matsumoto, Kiyoshi; Tanaka, Hiroshi

    1999-05-01

    Long-term measurements of several trace gases and aerosols were carried out from December 1994 to October 1996 at Ogasawara Hahajima Island over the northwestern Pacific Ocean. The continental impact on the concentrations of sulfur compounds, ozone (O3), and cloud condensation nuclei (CCN) was estimated on the basis of the classification of air mass into seven types by isentropic trajectory analysis. From May to October, the air mass originating from the central North Pacific Ocean is predominant and regarded as the clean marine air for the concentrations of sulfur compounds and CCN. From the results of the molar ratio of methane sulfonic acid to non-sea-salt sulfate (NSS) and the positive correlation between dimethylsulfide (DMS) and CCN in this air mass it can be concluded that DMS largely contributes to the production of NSS and CCN. On the other hand, continental and anthropogenic substances are preferably transported to the northwestern Pacific Ocean by the predominant continental air mass from November to March. The enhancement of concentrations by the outflow from the Asian continent are estimated by a factor of 2.8 for O3, 3.9 for SO2, 3.5 for CCN activated at 0.5% supersaturation (0.5% CCN), 4.7 for 1.0% CCN, and 5.5 for NSS. Moreover, the CCN supersaturation spectra are also affected by the continental substances resulting in factor 2 of enhancement of cloud droplet number concentration. The diurnal variations of DMS and O3 for each air mass show a pattern of daytime minimum and nighttime maximum, which are typically found in remote ocean, even though those amplitudes are different for each air mass. Consequently, it can be concluded that the influence of nitric oxides (NOx) for the daytime O3 production and nitrate (NO3) radical for the nighttime oxidation of DMS are small even in the continental air mass.

  13. Assessing the potential for dimethylsulfide enrichment at the sea surface and its influence on air-sea flux

    NASA Astrophysics Data System (ADS)

    Walker, Carolyn F.; Harvey, Mike J.; Smith, Murray J.; Bell, Thomas G.; Saltzman, Eric S.; Marriner, Andrew S.; McGregor, John A.; Law, Cliff S.

    2016-09-01

    The flux of dimethylsulfide (DMS) to the atmosphere is generally inferred using water sampled at or below 2 m depth, thereby excluding any concentration anomalies at the air-sea interface. Two independent techniques were used to assess the potential for near-surface DMS enrichment to influence DMS emissions and also identify the factors influencing enrichment. DMS measurements in productive frontal waters over the Chatham Rise, east of New Zealand, did not identify any significant gradients between 0.01 and 6 m in sub-surface seawater, whereas DMS enrichment in the sea-surface microlayer was variable, with a mean enrichment factor (EF; the concentration ratio between DMS in the sea-surface microlayer and in sub-surface water) of 1.7. Physical and biological factors influenced sea-surface microlayer DMS concentration, with high enrichment (EF > 1.3) only recorded in a dinoflagellate-dominated bloom, and associated with low to medium wind speeds and near-surface temperature gradients. On occasion, high DMS enrichment preceded periods when the air-sea DMS flux, measured by eddy covariance, exceeded the flux calculated using National Oceanic and Atmospheric Administration (NOAA) Coupled-Ocean Atmospheric Response Experiment (COARE) parameterized gas transfer velocities and measured sub-surface seawater DMS concentrations. The results of these two independent approaches suggest that air-sea emissions may be influenced by near-surface DMS production under certain conditions, and highlight the need for further study to constrain the magnitude and mechanisms of DMS production in the sea-surface microlayer.

  14. Air-sea exchange of dimethylsulfide in the Southern Ocean: Measurements from SO GasEx compared to temperate and tropical regions

    NASA Astrophysics Data System (ADS)

    Yang, M.; Blomquist, B. W.; Fairall, C. W.; Archer, S. D.; Huebert, B. J.

    2011-04-01

    In the Southern Ocean Gas Exchange Experiment (SO GasEx), we measured an atmospheric dimethylsulfide (DMS) concentration of 118 ± 54 pptv (1σ), a DMS sea-to-air flux of 2.9 ± 2.1 μmol m-2 d-1 by eddy covariance, and a seawater DMS concentration of 1.6 ± 0.7 nM. Dividing flux by the concurrent air-sea concentration difference yields the transfer velocity of DMS (kDMS). The kDMS in the Southern Ocean was significantly lower than previous measurements in the equatorial east Pacific, Sargasso Sea, northeast Atlantic, and southeast Pacific. Normalizing kDMS for the temperature dependence in waterside diffusivity and solubility results in better agreement among various field studies and suggests that the low kDMS in the Southern Ocean is primarily due to colder temperatures. The higher solubility of DMS at a lower temperature results in greater airside control and less transfer of the gas by bubbles formed from breaking waves. The final normalized DMS transfer velocity is similar to k of less soluble gases such as carbon dioxide in low-to-moderate winds; in high winds, DMS transfer velocity is significantly lower because of the reduced bubble-mediated transfer.

  15. Differential response of planktonic primary, bacterial, and dimethylsulfide production rates to static vs. dynamic light exposure in upper mixed-layer summer sea waters

    NASA Astrophysics Data System (ADS)

    Galí, M.; Simó, R.; Pérez, G. L.; Ruiz-González, C.; Sarmento, H.; Royer, S.-J.; Fuentes-Lema, A.; Gasol, J. M.

    2013-12-01

    Microbial plankton experience short-term fluctuations in total solar irradiance and in its spectral composition as they are vertically moved by turbulence in the oceanic upper mixed layer (UML). The fact that the light exposure is not static but dynamic may have important consequences for biogeochemical processes and ocean-atmosphere fluxes. However, most biogeochemical processes other than primary production, like bacterial production or dimethylsulfide (DMS) production, are seldom measured in sunlight and even less often in dynamic light fields. We conducted four experiments in oligotrophic summer stratified Mediterranean waters, where a sample from the UML was incubated in ultraviolet (UV)-transparent bottles at three fixed depths within the UML and on a vertically moving basket across the same depth range. We assessed the response of the phyto- and bacterioplankton community with physiological indicators based on flow cytometry singe-cell measurements, fast repetition rate fluorometry (FRRf), phytoplankton pigment concentrations and particulate light absorption. Dynamic light exposure caused a subtle disruption of the photoinhibition and photoacclimation processes associated with ultraviolet radiation (UVR), which slightly alleviated bacterial photoinhibition but did not favor primary production. Gross DMS production (GPDMS) decreased sharply with depth in parallel to shortwave UVR, and displayed a dose-dependent response that mixing did not significantly disrupt. To our knowledge, we provide the first measurements of GPDMS under in situ UV-inclusive optical conditions.

  16. Differential response of planktonic primary, bacterial, and dimethylsulfide production rates to vertically-moving and static incubations in upper mixed-layer summer sea waters

    NASA Astrophysics Data System (ADS)

    Galí, M.; Simó, R.; Pérez, G. L.; Ruiz-González, C.; Sarmento, H.; Royer, S.-J.; Fuentes-Lema, A.; Gasol, J. M.

    2013-05-01

    Microbial plankton experience fluctuations in total solar irradiance and in its spectral composition as they are vertically moved by turbulence in the oceanic upper mixed layer (UML). The fact that the light exposure is not static but dynamic may have important consequences for biogeochemical processes and ocean-atmosphere fluxes. However, most biogeochemical processes other than primary production, like bacterial production or dimethylsulfide (DMS) production, are seldom measured in sunlight and even less often in dynamic light fields. We conducted four experiments in oligotrophic summer stratified Mediterranean waters, where a sample from the UML was incubated in ultraviolet (UV)-transparent bottles at three fixed depths within the UML and on a vertically-moving basket across the same depth range. We assessed the response of the phyto- and bacterioplankton community with physiological indicators based on flow cytometry singe-cell measurements, Fast Repetition Rate fluorometry (FRRf), phytoplankton pigment concentrations and particulate light absorption. Dynamic light exposure caused a disruption of the photoinhibition and photoacclimation processes associated to ultraviolet radiation (UVR), which slightly alleviated bacterial photoinhibition but did not favor primary production. Gross DMS production (GPDMS) decreased sharply with depth in parallel to shortwave UVR, and displayed a dose-dependent response that mixing did not significantly disrupt. To our knowledge, we provide the first measurements of GPDMS under in situ UV-inclusive optical conditions.

  17. Molecular genetic analysis of a dimethylsulfoniopropionate lyase that liberates the climate-changing gas dimethylsulfide in several marine alpha-proteobacteria and Rhodobacter sphaeroides.

    PubMed

    Curson, A R J; Rogers, R; Todd, J D; Brearley, C A; Johnston, A W B

    2008-03-01

    The alpha-proteobacterium Sulfitobacter EE-36 makes the gas dimethylsulfide (DMS) from dimethylsulfoniopropionate (DMSP), an abundant antistress molecule made by many marine phytoplankton. We screened a cosmid library of Sulfitobacter for clones that conferred to other bacteria the ability to make DMS. One gene, termed dddL, was sufficient for this phenotype when cloned in pET21a and introduced into Escherichia coli. Close DddL homologues exist in the marine alpha-proteobacteria Fulvimarina, Loktanella Oceanicola and Stappia, all of which made DMS when grown on DMSP. There was also a dddL homologue in Rhodobacter sphaeroides strain 2.4.1, but not in strain ATCC 17025; significantly, the former, but not the latter, emits DMS when grown with DMSP. Escherichia coli containing the cloned, overexpressed dddL genes of R. sphaeroides 2.4.1 and Sulfitobacter could convert DMSP to acrylate plus DMS. This is the first identification of such a 'DMSP lyase'. Thus, DMS can be made either by this DddL lyase or by a DMSP acyl CoA transferase, specified by dddD, a gene that we had identified in several other marine bacteria.

  18. Dimethylsulfide/cloud condensation nuclei/climate system - Relevant size-resolved measurements of the chemical and physical properties of atmospheric aerosol particles

    NASA Technical Reports Server (NTRS)

    Quinn, P. K.; Covert, D. S.; Bates, T. S.; Kapustin, V. N.; Ramsey-Bell, D. C.; Mcinnes, L. M.

    1993-01-01

    The mass and number relationships occurring within the atmospheric dimethylsulfide/cloud condensation nuclei (CCN)/climate system, using simultaneous measurements of particulate phase mass size distributions of nss SO4(2-), methanesulfonic acid (MSA), and NH4(+); number size distributions of particles having diameters between 0.02 and 9.6 microns; CCN concentrations at a supersaturation of 0.3 percent; relative humidity; and temperature, obtained for the northeastern Pacific Ocean in April and May 1991. Based on these measurements, particulate nss SO4(2-), MSA, and NH4(+) mass appeared to be correlated with both particle effective surface area and number in the accumulation mode size range (0.16 to 0.5 micron). No correlations were found in the size range below 0.16 micron. A correlation was also found between nss SO4(2-) mass and the CCN number concentration, such that a doubling of the SO4(2-) mass corresponded to a 40 percent increase in the CCN number concentration. However, no correlation was found between MSA mass and CCN concentration.

  19. Spatial variations of dimethylsulfide and dimethylsulfoniopropionate in the surface microlayer and in the subsurface waters of the South China Sea during springtime.

    PubMed

    Yang, Gui-Peng; Jing, Wei-Wen; Kang, Zhi-Qiang; Zhang, Hong-Hai; Song, Gui-Sheng

    2008-02-01

    Spatial variations in dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) were surveyed in the surface microlayer and in the subsurface waters of the low productivity South China Sea in May 2005. Overall, average subsurface water concentrations of DMS and DMSP of dissolved (DMSPd) and particulate (DMSPp) fractions were 1.74 (1.00-2.50), 3.92 (2.21-6.54) and 6.06 (3.40-8.68) nM, respectively. No enrichment in DMS and DMSPp was observed in the microlayer. In contrast, the microlayer showed a DMSPd enrichment, with an average enrichment factor (EF, defined as the ratio of the microlayer concentration to subsurface water concentration) of 1.40. In the study area, none of the sulfur components were correlated with chlorophyll a. An important finding in this study was that DMS, DMSP and chlorophyll a concentrations in the surface microlayer were respectively correlated with those in the subsurface water, suggesting a close linkage between these two water bodies. The ratios of DMS:Chl-a and DMSPp:Chl-a showed a gradually increasing trend from North to South. This might be due to changes in the proportion of DMSP producers in the phytoplankton community with the increased surface seawater temperature. A clear diurnal variation in the DMS and DMSP concentrations was observed at an anchor station with the highest concentrations appearing during the day and the lowest concentrations during the night. The higher DMS and DMSP concentrations during daytime might be attributed to the light-induced increase in both algal synthesis and exudation of DMSP and biological production of DMS. The mean flux of DMS from the investigated area to the atmosphere was estimated to be 2.06 micromo lm(-2)d(-1). This low DMS emission flux, together with the low DMS surface concentrations was attributed to the low productivity in this sea.

  20. Hydroxide decomposition of dimethylsulfoniopropionate to form dimethylsulfide. [in sea water

    NASA Technical Reports Server (NTRS)

    Dacey, John W. H.; Blough, Neil V.

    1987-01-01

    The kinetics of DMS production resulting from reaction of OH(-) with DMSP were investigated as a function of hydroxide concentration and temperature. The reaction was first-order with respect to DMSP and OH(-). The second order rate constant at 20+/-1 C is 0.0044/M/sec. The activation energy for this reaction is 14.4 kcal/mode. The investigation indicates that the rate of reaction of DMSP with OH(-) is very slow at the pH of seawater, suggesting that DMSP, which may be a major precursor of DMS in seawater, decomposes in the ocean by other mechanisms. A bacterium which produces DMS from DMSP quantitatively at rates many orders of magnitude higher than indicated by OH(-1) decomposition has been cultured, suggesting that enzymatic processes accelerate the production of DMS from DMSP in seawater.

  1. Diatom aggregation and dimethylsulfide production in phytoplankton blooms

    SciTech Connect

    Crocker, K.M.

    1994-01-01

    Phytoplankton blooms are crucial links in many of the earth's biogeochemical cycles. Blooms take up atmospheric carbon through photosynthesis, and sequester it on the ocean floor by sinking. Aggregation of single cells into [open quote]marine snow[close quote] particles speeds up the sinking of algal cells. Laboratory studies investigating the process of aggregation show that some species have a higher probability of aggregating than others, and that there exist several mechanisms for causing aggregation. Field studies confirm that some species are more likely to be found in aggregates than in the surrounding seawater. High latitude Premnesiophyte blooms are found to produce large amounts of dimethylsulflde (DMS), believed to be an important chemical in global thermoregulation. DMS is found to vary diurnally, possibly due to photooxidation by ultraviolet light. This possibility links the effects of DMS on cloud formation with the effects of increased ultraviolet light penetrating the earths ozone layer.

  2. Stimulation of gross dimethylsulfide (DMS) production by solar radiation

    NASA Astrophysics Data System (ADS)

    Galí, Martí; Saló, Violeta; Almeda, Rodrigo; Calbet, Albert; Simó, Rafel

    2011-08-01

    Oceanic gross DMS production (GP) exerts a fundamental control on the concentration and the sea-air flux of this climatically-active trace gas. However, it is a poorly constrained process, owing to the complexity of the microbial food web processes involved and their interplay with physical forcing, particularly with solar radiation. The “inhibitor method”, using dimethyldisulfide (DMDS) or other compounds to inhibit bacterial DMS consumption, has been frequently used to determine GP in dark incubations. In the work presented here, DMDS addition was optimized for its use in light incubations. By comparing simultaneous dark and light measurements of GP in meso- to ultraoligotrophic waters, we found a significant enhancement of GP in natural sunlight in 7 out of 10 experiments. Such stimulation, which was generally between 30 and 80% on a daily basis, occurred throughout contrasting microbial communities and oceanographic settings.

  3. Influence of wind speed averaging on estimates of dimethylsulfide emission fluxes

    DOE PAGES

    Chapman, E. G.; Shaw, W. J.; Easter, R. C.; Bian, X.; Ghan, S. J.

    2002-12-03

    The effect of various wind-speed-averaging periods on calculated DMS emission fluxes is quantitatively assessed. Here, a global climate model and an emission flux module were run in stand-alone mode for a full year. Twenty-minute instantaneous surface wind speeds and related variables generated by the climate model were archived, and corresponding 1-hour-, 6-hour-, daily-, and monthly-averaged quantities calculated. These various time-averaged, model-derived quantities were used as inputs in the emission flux module, and DMS emissions were calculated using two expressions for the mass transfer velocity commonly used in atmospheric models. Results indicate that the time period selected for averaging wind speedsmore » can affect the magnitude of calculated DMS emission fluxes. A number of individual marine cells within the global grid show DMS emissions fluxes that are 10-60% higher when emissions are calculated using 20-minute instantaneous model time step winds rather than monthly-averaged wind speeds, and at some locations the differences exceed 200%. Many of these cells are located in the southern hemisphere where anthropogenic sulfur emissions are low and changes in oceanic DMS emissions may significantly affect calculated aerosol concentrations and aerosol radiative forcing.« less

  4. Dimethylsulfide emissions over the multi-year ice of the western Weddell Sea

    NASA Astrophysics Data System (ADS)

    Zemmelink, H. J.; Dacey, J. W. H.; Houghton, L.; Hintsa, E. J.; Liss, P. S.

    2008-03-01

    This study, conducted in December 2004, is the first to present observations of DMS in a snow pack covering the multi-year sea ice of the western Weddell Sea. The snow layer is important because it is the interface through which DMS needs to be transported in order to be emitted directly from the ice to the overlying atmosphere. High concentrations of DMS, up to 6000 nmol m-3, were found during the first weeks of December but concentrations sharply decline as late spring-early summer progresses. This implies that DMS contained in sea ice is efficiently vented through the snow into the atmosphere. Indeed, field measurements by relaxed eddy accumulation indicate an average release of 11 μmol DMS m-2 d-1 from the ice and snow throughout December.

  5. Dimethylsulfide oxidation over the tropical South Atlantic: OH and other oxidants

    NASA Technical Reports Server (NTRS)

    Hemming, Brooke L.; Vastano, John A.; Chatfield, Robert B.; Andreae, Meinrat O.; Hildemann, Lynn M.

    1994-01-01

    The general course of events in the formation of a marine cloud begins with the emission of species which can eventually serve as nuclei around which water can condense to form a cloud droplet. In remote marine regions, cloud condensation nuclei (CCN) are primarily composed of sulfate, in either its acid or ammonium salt form. Most sulfate in these regions is the product of atmospheric oxidation of dimethyl sulfide (DMS), a reduced sulfur gas that is released by phytoplankton at the ocean surface. Therefore, in order to effectively quantify the links in the cloud-formation cycle, one must begin with a well-defined description of the atmospheric chemistry of DMS. The intent of this project has been to initiate development of a comprehensive model of the chemistry and dynamics responsible for the formation of clouds in the remote marine boundary layer. The primary tool in this work has been the Global/Regional Atmospheric Chemistry Event Simulator (GRACES), a global atmospheric chemistry model, which is under development within the Atmospheric Chemistry and Dynamics Branch of NASA-Ames Research Center. In this effort, GRACES was used to explore the first chemical link between DMS and sulfate by modeling the diurnal variation of DMS.

  6. Correlation between satellite-derived aerosol characteristics and oceanic dimethylsulfide (DMS). Master's thesis

    SciTech Connect

    Shema, R.A.

    1988-12-01

    Since the turn of the century, the earth's climate has fluctuated between warming and cooling cycles. A warming cycle has been observed in the early 1900's. The rising global temperature has been attributed to CO/sub 2/ release from the burning of fossil fuels. The absorption of IR energy emitted from the earth, or greenhouse effect , brought concern that continued warming would melt polar ice caps and permanently change global climate. However, beginning in the mid-1940's, atmospheric cooling was observed. A possible contribution to the cooling trend is an increase in the numbers of relatively small aerosol particles. These particles are efficient scatters of solar radiation. An increase in the number of scattering events causes a higher albedo, thereby creating a cooler planet. McCormick and Ludwig (1967) have presented arguments to show this relationship. Approximately forty years later, in the early 1980's, warming of the earth's climate again has been observed.

  7. Influence of wind speed averaging on estimates of dimethylsulfide emission fluxes

    SciTech Connect

    Chapman, E. G.; Shaw, W. J.; Easter, R. C.; Bian, X.; Ghan, S. J.

    2002-12-03

    The effect of various wind-speed-averaging periods on calculated DMS emission fluxes is quantitatively assessed. Here, a global climate model and an emission flux module were run in stand-alone mode for a full year. Twenty-minute instantaneous surface wind speeds and related variables generated by the climate model were archived, and corresponding 1-hour-, 6-hour-, daily-, and monthly-averaged quantities calculated. These various time-averaged, model-derived quantities were used as inputs in the emission flux module, and DMS emissions were calculated using two expressions for the mass transfer velocity commonly used in atmospheric models. Results indicate that the time period selected for averaging wind speeds can affect the magnitude of calculated DMS emission fluxes. A number of individual marine cells within the global grid show DMS emissions fluxes that are 10-60% higher when emissions are calculated using 20-minute instantaneous model time step winds rather than monthly-averaged wind speeds, and at some locations the differences exceed 200%. Many of these cells are located in the southern hemisphere where anthropogenic sulfur emissions are low and changes in oceanic DMS emissions may significantly affect calculated aerosol concentrations and aerosol radiative forcing.

  8. High wind speed measurements of dimethylsulfide air/sea gas transfer by eddy correlation in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Bell, T. G.; De Bruyn, W. J.; Miller, S. D.; Saltzman, E. S.; Slawksy, L.; Stacy, B.; Callaghan, A. H.

    2012-12-01

    Air/sea dimethylsulphide (DMS) fluxes and gas transfer coefficients (kDMS) were measured by eddy correlation over the western North Atlantic Ocean during June/July 2011 aboard the R/V Knorr. Atmospheric and seawater DMS were measured using atmospheric pressure chemical ionization mass spectrometry (API-CIMS). Seawater DMS was measured continuously from the ship's underway system using a porous membrane equilibrator and API-CIMS. The cruise included regions of high biological productivity, wind speeds from 0-18 m/sec and whitecap areas of 0-5%. Four stations were occupied during the cruise for periods of 24-36 hours. In general, the stations exhibited a linear relationship between kDMS and wind speed, although there were significant variations in the slope of this relationship. One of the stations showed kDMS increasing with wind speed to 10 m/sec and then levelling off at higher wind speeds. The data from this cruise suggest that gas transfer can vary substantially due to parameters other than wind speed, most likely sea state and surfactants.

  9. Inhibition of Ammonia Oxidation in Nitrosomonas europaea by Sulfur Compounds: Thioethers Are Oxidized to Sulfoxides by Ammonia Monooxygenase

    PubMed Central

    Juliette, Lisa Y.; Hyman, Michael R.; Arp, Daniel J.

    1993-01-01

    Organic sulfur compounds are well-known nitrification inhibitors. The inhibitory effects of dimethylsulfide, dimethyldisulfide, and ethanethiol on ammonia oxidation by Nitrosomonas europaea were examined. Both dimethylsulfide and dimethyldisulfide were weak inhibitors of ammonia oxidation and exhibited inhibitory characteristics typical of substrates for ammonia monooxygenase (AMO). Depletion of dimethylsulfide required O2 and was prevented with either acetylene or allylthiourea, two inhibitors of AMO. The inhibition of ammonia oxidation by dimethylsulfide was examined in detail. Cell suspensions incubated in the presence of ammonia oxidized dimethylsulfide to dimethyl sulfoxide. Depletion of six other thioethers was also prevented by treating cell suspensions with either allylthiourea or acetylene. The oxidative products of three thioethers were identified as the corresponding sulfoxides. The amount of sulfoxide formed accounted for a majority of the amount of sulfide depleted. By using gas chromatography coupled with mass spectrometry, allylmethylsulfide was shown to be oxidized to allylmethylsulfoxide by N. europaea with the incorporation of a single atom of 18O derived from 18O2 into the sulfide. This result supported our conclusion that a monooxygenase was involved in the oxidation of allylmethylsulfide. The thioethers are concluded to be a new class of substrates for AMO. This is the first report of the oxidation of the sulfur atom by AMO in whole cells of N. europaea. The ability of N. europaea to oxidize dimethylsulfide is not unique among the ammonia-oxidizing bacteria. Nitrosococcus oceanus, a marine nitrifier, was also demonstrated to oxidize dimethylsulfide to dimethyl sulfoxide. PMID:16349086

  10. GTE_PEMTB_DC8 Parameters 15

    Atmospheric Science Data Center

    2013-02-19

    ... Parameters:  NMHC/Halocarbons/Alkyl Nitrates: Methyl Chloride F-12 F-114 F-11 HCFC-141B HCFC-134a HCFC-22 ... Bromoform H-1211 F-113 H-2402 Methyl Iodide Dimethylsulfide Methyl nitrate Ethyl nitrate i-propyl ...

  11. GTE_PEMTB_P3B Parameters 17

    Atmospheric Science Data Center

    2013-02-19

    ... Parameters:  NMHC/Halocarbons/Alkyl Nitrates: Methyl Chloride F-12 F-114 F-11 HCFC-141B HCFC-134a HCFC-22 ... Bromoform H-1211 F-113 H-2402 Methyl Iodide Dimethylsulfide Methyl nitrate Ethyl nitrate i-propyl ...

  12. Technical note: Examining ozone deposition over seawater

    EPA Science Inventory

    Surface layer resistance plays an important role in determining ozone deposition velocity over sea-water and can be influenced by chemical interactions at the air-water interface. Here, we examine the effect of chemical interactions of iodide, dimethylsulfide, dissolved organic c...

  13. Low level measurements of atmospheric DMS, H2S, and SO2 for GTE/CITE-3

    NASA Technical Reports Server (NTRS)

    Saltzman, Eric; Cooper, David

    1991-01-01

    This project involved the measurement of atmospheric dimethylsulfide (DMS) and hydrogen sulfide (H2S) as part of the GTE/CITE-3 instrument intercomparison program. The two instruments were adapted for use on the NASA Electra aircraft and participated in all phases of the mission. This included ground-based measurements of NIST-provided standard gases and a series of airborne missions over the Western Atlantic Ocean. Analytical techniques used are described and the results are summarized.

  14. Selenium detoxification by volatilization and precipitation in aquatic plants

    SciTech Connect

    Fan, T.W.M.; Higashi, R.M.

    1995-12-31

    The narrow margin of requirement and toxicity for selenium makes it a difficult pollution problem to solve. Selenium bioaccumulation has been a major threat to wildlife in California and is becoming a major concern in the San Francisco Bay/Estuaries. Despite the past efforts in Se nutrition, chemistry, and remediation, its toxicity and detoxification mechanism(s) in wildlife, particularly primary producers, is still unclear, due to a lack of understanding in Se biochemistry. This is becoming a critical issue in assessing Se risk and remediation. To address this gap, the authors have been characterizing Se speciation and its linkage to detoxification mechanism(s) of two indigenous aquatic plants, duckweed (Lemna minor) and a microphyte (Chlorella). Using GT-MS analysis, they found that Chlorella monocultures transformed Se oxyanions into volatile dimethylselenide and dimethyidiselenide and into insoluble So at extremely high Se (up to 750 ppm) concentrations. This alga did not accumulate selenomethionine which is among the most toxic forms of Se to wildlife. Dimethylsulfide was also volatilized, consistent with the hypothesis that dimethylsulfide/dimethylselenide emissions share a similar biochemical pathway. Se-treated Chlorella biomass released dimethylsulfide/dimethylselenide upon alkaline hydrolysis, suggesting the presence of dimethylsulfonium and dimethylselenonium propionates. Dimethylsulfoniumpropionate is known as an osmoprotectant in marine phytoplankton and as a major contributor to global biogenic dimethylsulfide emissions. Dimethylselenoniumpropionate has not been identified previously and may be a byproduct of dimethylsulfoniumpropionate synthesis. The unusual Se tolerance of Chlorella may be due to its ability to volatilize and precipitate Se. Such activities may be utilized for in situ Se bioremediation. Similar investigations with duckweed is underway.

  15. Factors controlling emissions of dimethylsulphide from salt marshes

    NASA Technical Reports Server (NTRS)

    Dacey, John W. H.; Wakeham, Stuart G.; King, Gary M.

    1987-01-01

    Salt marshes are presently identified as systems exhibiting high area-specific sulfur emission in the form of dimethylsulfide (DMS) and H2S, with the former predominating in vegetated areas of the marshes. Attention is presently given to the distribution of DMS in salt marshes; it is found that this compound primarily arises from physiological processes in the leaves of higher plants, especially the grass species Spartina alterniflora. Uncertainties associated with DMS emission measurements are considered.

  16. Technical note: Examining ozone deposition over seawater

    NASA Astrophysics Data System (ADS)

    Sarwar, Golam; Kang, Daiwen; Foley, Kristen; Schwede, Donna; Gantt, Brett; Mathur, Rohit

    2016-09-01

    Surface layer resistance plays an important role in determining ozone deposition velocity over sea-water and can be influenced by chemical interactions at the air-water interface. Here, we examine the effect of chemical interactions of iodide, dimethylsulfide, dissolved organic carbon, and bromide in seawater on ozone deposition. We perform a series of simulations using the hemispheric Community Multiscale Air Quality model for summer months in the Northern Hemisphere. Our results suggest that each chemical interaction enhances the ozone deposition velocity and decreases the atmospheric ozone mixing ratio over seawater. Iodide enhances the median deposition velocity over seawater by 0.023 cm s-1, dissolved organic carbon by 0.021 cm s-1, dimethylsulfide by 0.002 cm s-1, and bromide by ∼0.0006 cm s-1. Consequently, iodide decreases the median atmospheric ozone mixing ratio over seawater by 0.7 ppb, dissolved organic carbon by 0.8 ppb, dimethylsulfide by 0.1 ppb, and bromide by 0.02 ppb. In a separate model simulation, we account for the effect of dissolved salts in seawater on the Henry's law constant for ozone and find that it reduces the median deposition velocity by 0.007 cm s-1 and increases surface ozone mixing ratio by 0.2 ppb. The combined effect of these processes increases the median ozone deposition velocity over seawater by 0.040 cm s-1, lowers the atmospheric ozone mixing ratio by 5%, and slightly improves model performance relative to observations.

  17. Particle nucleation in the tropical boundary layer and its coupling to marine sulfur sources

    PubMed

    Clarke; Davis; Kapustin; Eisele; Chen; Paluch; Lenschow; Bandy; Thornton; Moore; Mauldin; Tanner; Litchy; Carroll; Collins; Albercook

    1998-10-01

    New particle formation in a tropical marine boundary layer setting was characterized during NASA's Pacific Exploratory Mission-Tropics A program. It represents the clearest demonstration to date of aerosol nucleation and growth being linked to the natural marine sulfur cycle. This conclusion was based on real-time observations of dimethylsulfide, sulfur dioxide, sulfuric acid (gas), hydroxide, ozone, temperature, relative humidity, aerosol size and number distribution, and total aerosol surface area. Classic binary nucleation theory predicts no nucleation under the observed marine boundary layer conditions.

  18. Insights into the reactivity of gold-dithiocarbamato anticancer agents toward model biomolecules by using multinuclear NMR spectroscopy.

    PubMed

    Boscutti, Giulia; Marchiò, Luciano; Ronconi, Luca; Fregona, Dolores

    2013-09-27

    Some gold(III)-dithiocarbamato derivatives of either single amino acids or oligopeptides have shown promise as potential anticancer agents, but their capability to interact with biologically relevant macromolecules is still poorly understood. We investigated the affinity of the representative complex [Au(III)Br2(dtc-Sar-OCH3)] (dtc: dithiocarbamate; Sar: sarcosine (N-methylglycine)) with selected model molecules for histidine-, methionine-, and cysteine-rich proteins (that is, 1-methylimidazole, dimethylsulfide, and N-acetyl-L-cysteine, respectively). In particular, detailed mono- and multinuclear NMR studies, in combination with multiple (13)C/(15)N enrichments, allowed interactions to be followed over time and indicated somewhat unexpected reaction pathways. Whereas dimethylsulfide proved to be unreactive, a sudden multistep redox reaction occurred in the presence of the other potential sulfur donor, N-acetyl-L-cysteine (confirmed if glutathione was used instead). On the other hand, 1-methylimidazole underwent an unprecedented acid-base reaction with the gold(III) complex, rather than the expected coordination to the metal center by replacing, for instance, a bromide. Our results are discussed herein and compared with the data available in the literature on related complexes; our findings confirm that the peculiar reactivity of gold(III)-dithiocarbamato complexes can lead to novel reaction pathways and, therefore, to new cytotoxic mechanisms in cancer cells. PMID:24038383

  19. Genetic Basis for Metabolism of Methylated Sulfur Compounds in Methanosarcina Species

    PubMed Central

    Fu, He

    2015-01-01

    ABSTRACT Methanosarcina acetivorans uses a variety of methylated sulfur compounds as carbon and energy sources. Previous studies implicated the mtsD, mtsF, and mtsH genes in catabolism of dimethylsulfide, but the genes required for use of other methylsulfides have yet to be established. Here, we show that a four-gene locus, designated mtpCAP-msrH, is specifically required for growth on methylmercaptopropionate (MMPA). The mtpC, mtpA, and mtpP genes encode a putative corrinoid protein, a coenzyme M (CoM) methyltransferase, and a major facilitator superfamily (MFS) transporter, respectively, while msrH encodes a putative transcriptional regulator. Mutants lacking mtpC or mtpA display a severe growth defect in MMPA medium but are unimpaired during growth on other substrates. The mtpCAP genes comprise a transcriptional unit that is highly and specifically upregulated during growth on MMPA, whereas msrH is monocistronic and constitutively expressed. Mutants lacking msrH fail to transcribe mtpCAP and grow poorly in MMPA medium, consistent with the assignment of its product as a transcriptional activator. The mtpCAP-msrH locus is conserved in numerous marine methanogens, including eight Methanosarcina species that we showed are capable of growth on MMPA. Mutants lacking the mtsD, mtsF, and mtsH genes display a 30% reduction in growth yield when grown on MMPA, suggesting that these genes play an auxiliary role in MMPA catabolism. A quadruple ΔmtpCAP ΔmtsD ΔmtsF ΔmtsH mutant strain was incapable of growth on MMPA. Reanalysis of mtsD, mtsF, and mtsH mutants suggests that the preferred substrate for MtsD is dimethylsulfide, while the preferred substrate for MtsF is methanethiol. IMPORTANCE Methylated sulfur compounds play pivotal roles in the global sulfur and carbon cycles and contribute to global temperature homeostasis. Although the degradation of these molecules by aerobic bacteria has been well studied, relatively little is known regarding their fate in anaerobic

  20. Quality and aromatic sensory descriptors (mainly fresh and dry fruit character) of Spanish red wines can be predicted from their aroma-active chemical composition.

    PubMed

    San-Juan, Felipe; Ferreira, Vicente; Cacho, Juan; Escudero, Ana

    2011-07-27

    A satisfactory model explaining quality could be built in a set of 25 high quality Spanish red wines, by aroma-active chemical composition. The quality of the wines was positively correlated with the wine content in fruity esters, acids, enolones, and wood derived compounds, and negatively with phenylacetaldehyde, acetic acid, methional, and 4-ethylphenol. Wine fruitiness was demonstrated to be positively related not only to the wine content on fruity esters and enolones, but to wine volatile fatty acids. Fruitiness is strongly suppressed by 4-ethylphenol, acetic acid, phenylacetaldehyde, and methional, this involved in the perception of dry-fruit notes. Sensory effects were more intense in the presence of β-damascenone and β-ionone. A satisfactory model explaining animal notes could be built. Finally, the vegetal character of this set of wines could be related to the combined effect of dimethylsulfide (DMS), 1-hexanol, and methanethiol.

  1. Eutrophication counteracts ocean acidification effects on DMS emissions

    NASA Astrophysics Data System (ADS)

    Gypens, Nathalie; Borges, Alberto V.

    2014-05-01

    The accumulation of anthropogenic CO2 in the ocean has altered carbonate chemistry in surface waters since pre-industrial times and is expected to continue to do so in the coming centuries (ocean acidification). Changes in carbonate chemistry can modify the rates and fates of marine primary production and calcification. Available information from manipulative experiments suggests that the emission of dimethylsulfide (DMS) would decrease in response to ocean acidification. However, in coastal environments it has been shown that carbonate chemistry in surface waters has strongly responded to eutrophication during the last 50 years. Here, we test the hypothesis that DMS emissions also strongly respond to eutrophication in addition to ocean acidification at decadal timescales. We use the MIRO-BIOGAS model setup in the strongly eutrophied Southern Bight of the North Sea characterized by intense blooms of Phaeocystis that are strong producers of dimethylsulfoniopropionate (DMSP), the precursor of DMS.

  2. The cycle of biogenic sulfur compounds over the Amazon Basin. I - Dry season

    NASA Technical Reports Server (NTRS)

    Andreae, M. O.; Andreae, T. W.

    1988-01-01

    The concentrations of SO2, methylmercaptan, dimethylsulfide, H2S, aerosol sulfate, and methanesulfonate over the Amazon Basin during the July/August dry season were determined from samples collected by the NASA research aircraft. The results indicate that biogenic emissions represent an important, if not the dominant, source of sulfur to the atmosphere over Amazonia. Per unit area, the wet continental tropics appear to have about the same reduced sulfur emission flux as the oceanic area average (about 6 nmol/sq m per min), consistent with the fact that the aerosol sulfate concentration over the Amazon Basin is similar to the excess sulfate levels over the remote oceans. However, since the wet tropical continents represent only about 3 percent of the earth's surface, their global contribution is modest; it is also small relative to the anthropogenic emissions from fossil fuel burning.

  3. Dimethylsulfoxide and dimethylsulfone in the marine atmosphere

    NASA Astrophysics Data System (ADS)

    Harvey, George R.; Lang, Russell F.

    1986-01-01

    New isolation and detection methods were developed to measure dimethylsulfoxide (DMSO) and dimethylsulfone (DMSO2) in marine rain and marine air masses. Central equatorial Pacific rain contained 1 to 10 µg/ℓ of each of these compounds. Uncontaminated air sampled off Miami contained 2 to 6 ng/m³ of each component. These concentrations suggest that DMSO and DMSO2 may be as significant as dimethylsulfide (DMS) in marine sulfur transport. In fact, DMSO was observed to undergo disproportionation in illuminated seawater or distilled water to DMS and DMSO2. This latter observation implies a partially reversible loop in the sulfur transport cycle and complicates the calculation of the flux of sulfur into the marine boundary layer.

  4. High concentrations and turnover rates of DMS, DMSP and DMSO in Antarctic sea ice

    NASA Astrophysics Data System (ADS)

    Asher, Elizabeth C.; Dacey, John W. H.; Mills, Matthew M.; Arrigo, Kevin R.; Tortell, Philippe D.

    2011-12-01

    The vast Antarctic sea-ice zone (SIZ) is a potentially significant source of the climate-active gas dimethylsulfide (DMS), yet few data are available on the concentrations and turnover rates of DMS and the related compounds dimethylsulfoniopropionate (DMSP) and dimethylsulfoxide (DMSO) in sea ice environments. Here we present new measurements characterizing the spatial variability of DMS, DMSP, and DMSO concentrations across the Antarctic SIZ, and results from tracer experiments quantifying the production rates of DMS from various sources. We observed extremely high concentrations (>200 nM) and turnover rates (>100 nM d-1) of DMS in sea-ice brines, indicating intense cycling of DMS/P/O. Our results demonstrate a previously unrecognized role for DMSO reduction as a major pathway of DMS production in Antarctic sea ice.

  5. Molecular detection and isolation from antarctica of methylotrophic bacteria able to grow with methylated sulfur compounds.

    PubMed

    Moosvi, S Azra; McDonald, Ian R; Pearce, David A; Kelly, Donovan P; Wood, Ann P

    2005-08-01

    This study is the first demonstration that a diverse facultatively methylotrophic microbiota exists in some Antarctic locations. PCR amplification of genes diagnostic for methylotrophs was carried out with bacterial DNA isolated from 14 soil and sediment samples from ten locations on Signy Island, South Orkney Islands, Antarctica. Genes encoding the mxaF of methanol dehydrogenase, the fdxA for Afipia ferredoxin, the msmA of methanesulfonate monooxygenase, and the 16S rRNA gene of Methylobacterium were detected in all samples tested. The mxaF gene sequences corresponded to those of Hyphomicrobium, Methylobacterium, and Methylomonas. Over 30 pure cultures of methylotrophs were isolated on methanesulfonate, dimethylsulfone, or dimethylsulfide from ten Signy Island lakes. Some were identified from 16S rRNA gene sequences (and morphology) as Hyphomicrobium species, strains of Afipia felis, and a methylotrophic Flavobacterium strain. Antarctic environments thus contain diverse methylotrophic bacteria, growing on various C1-substrates, including C1-sulfur compounds. PMID:16104352

  6. Culture-dependent and culture-independent methods reveal diverse methylotrophic communities in terrestrial environments.

    PubMed

    Eyice, Özge; Schäfer, Hendrik

    2016-01-01

    One-carbon compounds such as methanol, dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) are significant intermediates in biogeochemical cycles. They are suggested to affect atmospheric chemistry and global climate. Methylotrophic microorganisms are considered as a significant sink for these compounds; therefore, we analyzed the diversity of terrestrial bacteria that utilize methanol, DMS and DMSO as carbon and energy source using culture-dependent and culture-independent methods. The effect of habitat type on the methylotrophic community structure was also investigated in rhizosphere and bulk soil. While thirteen strains affiliated to the genera Hyphomicrobium, Methylobacterium, Pseudomonas, Hydrogenophaga, Rhodococcus, Flavobacterium and Variovorax were isolated, denaturing gradient gel electrophoresis revealed the dominance of Thiobacillus, Rhodococcus, Flavobacterium and Bacteroidetes species. Furthermore, methylotrophic communities that degrade methanol or DMS are not shaped by terrestrial habitat type. Rhizosphere and soil samples showed dominance of Methylophilus spp. and Methylovorus spp. for methanol enrichments; Cytophaga spp., Pseudomonas tremae and Thiobacillus thioparus for DMS enrichments. PMID:26475353

  7. Dimethylsulfoniopropionate (DMSP) cell quota of key Southern North Sea spring diatoms and Phaeocystis globosa.

    NASA Astrophysics Data System (ADS)

    Speeckaert, Gaëlle; Gypens, Nathalie; Lancelot, Christiane; Borges, Alberto V.

    2015-04-01

    Dimethylsulfide (DMS) in the ocean results of complex transformations of dimethylsulfoniopropionate (DMSP) produced by phytoplankton under different controls, including microbial transformation pathways. The phytoplankton composition is an important factor of variability due to the species dependence of the DMSP production and conversion to DMS. To better appraise the link between phytoplankton diversity and the DMS(P) cycling in the Southern North Sea we present measurements of the DMSP cell quota of key spring phytoplankton species (Skeletonema costatum, Thalassiosira rotula, Rhizosolenia delicatula, Asterionella glacialis, Nitzschia closterium, Chaetoceros debilis, Chaetoceros socialis and Phaeocystis globosa) isolated from the North Sea and maintained in non-limiting and axenic laboratory culture conditions. Results are discussed with regards to literature data and hypothesis currently used in DMS(P) biogeochemical models.

  8. Genomic insights into bacterial DMSP transformations.

    PubMed

    Moran, Mary Ann; Reisch, Chris R; Kiene, Ronald P; Whitman, William B

    2012-01-01

    Genomic and functional genomic methods applied to both model organisms and natural communities have rapidly advanced understanding of bacterial dimethylsulfoniopropionate (DMSP) degradation in the ocean. The genes for the two main pathways in bacterial degradation, routing DMSP to distinctly different biogeochemical fates, have recently been identified. The genes dmdA, -B, -C, and -D mediate the demethylation of DMSP and facilitate retention of carbon and sulfur in the marine microbial food web. The genes dddD, -L, -P, -Q, -W, and -Y mediate the cleavage of DMSP to dimethylsulfide (DMS), with important consequences for ocean-atmosphere sulfur flux. In ocean metagenomes, sufficient copies of these genes are present for approximately 60% of surface ocean bacterial cells to directly participate in DMSP degradation. The factors that regulate these two competing pathways remain elusive, but gene transcription analyses of natural bacterioplankton communities are making headway in unraveling the intricacies of bacterial DMSP processing in the ocean.

  9. Genomic Insights into Bacterial DMSP Transformations

    NASA Astrophysics Data System (ADS)

    Moran, Mary Ann; Reisch, Chris R.; Kiene, Ronald P.; Whitman, William B.

    2012-01-01

    Genomic and functional genomic methods applied to both model organisms and natural communities have rapidly advanced understanding of bacterial dimethylsulfoniopropionate (DMSP) degradation in the ocean. The genes for the two main pathways in bacterial degradation, routing DMSP to distinctly different biogeochemical fates, have recently been identified. The genes dmdA, -B, -C, and -D mediate the demethylation of DMSP and facilitate retention of carbon and sulfur in the marine microbial food web. The genes dddD, -L, -P, -Q, -W, and -Y mediate the cleavage of DMSP to dimethylsulfide (DMS), with important consequences for ocean-atmosphere sulfur flux. In ocean metagenomes, sufficient copies of these genes are present for ˜60% of surface ocean bacterial cells to directly participate in DMSP degradation. The factors that regulate these two competing pathways remain elusive, but gene transcription analyses of natural bacterioplankton communities are making headway in unraveling the intricacies of bacterial DMSP processing in the ocean.

  10. Methanohalophilus zhilinae sp. nov., an alkaliphilic, halophilic, methylotrophic methanogen

    NASA Technical Reports Server (NTRS)

    Mathrani, I. M.; Boone, D. R.; Mah, R. A.; Fox, G. E.; Lau, P. P.

    1988-01-01

    Methanohalophilus zhilinae, a new alkaliphilic, halophilic, methylotrophic species of methanogenic bacteria, is described. Strain WeN5T (T = type strain) from Bosa Lake of the Wadi el Natrun in Egypt was designated the type strain and was further characterized. This strain was nonmotile, able to catabolize dimethylsulfide, and able to grow in medium with a methyl group-containing substrate (such as methanol or trimethylamine) as the sole organic compound added. Sulfide (21 mM) inhibited cultures growing on trimethylamine. The antibiotic susceptibility pattern of strain WeN5T was typical of the pattern for archaeobacteria, and the guanine-plus-cytosine content of the deoxyribonucleic acid was 38 mol%. Characterization of the 16S ribosomal ribonucleic acid sequence indicated that strain WeN5T is phylogenetically distinct from members of previously described genera other than Methanohalophilus and supported the partition of halophilic methanogens into their own genus.

  11. Cryopreservation of marine thraustochytrids (Labyrinthulomycetes).

    PubMed

    Cox, Serena L; Hulston, Debbie; Maas, Elizabeth W

    2009-12-01

    In this research, the viability of three marine thraustochytrid isolates (fungoid protists) (WSG05, W15 and WH3) were investigated after freezing in liquid nitrogen. Five cryopreservative combinations containing horse serum, glycerol and dimethylsulfide (Me(2)SO) were used. The thraustochytrids were assessed directly after removal from liquid nitrogen and cell concentration measured for 10 days post-thawing. Results indicated that a combination of horse serum and Me(2)SO were the most effective cryoprotectants for each of the strains tested. Glycerol was only successful in producing growth in one of the strains once thawed. The protocols developed and tested in this study may have further application for cryopreserving other isolates in this class.

  12. Release and Consumption of DMSP from Emiliania Huxleyi during grazing by Oxyrrhis Marina

    NASA Technical Reports Server (NTRS)

    Wolfe, Gordon V.; Sherr, Evelyn B.; Sherr, Barry F.

    1994-01-01

    Degradation and release to solution of intracellular dimethylsulfoniopropionate (DMSP) from Emiliania huxleyi 370 was observed during grazing by the heterotrophic dinoflagellate Oxyrrhis marina in 24 h bottle incubations. Between 30 and 70% of the lost algal DMSP was metabolized by the grazers without production of dimethylsulfide (DMS) when grazer densities were 150 to 450/ml. The rest was released to solution and about 30% was converted to DMS by bacteria associated with the grazer culture. These experiments demonstrate that grazing by herbivorous protists may be an important sink for DMSP in marine waters, removing a potential source of DMS. Microzooplankton grazing may also indirectly increase the production of DMS by transferring algal DMSP to the dissolved pool, making it available for bacterial metabolism.

  13. Bacterial taxa that limit sulfur flux from the ocean.

    PubMed

    Howard, Erinn C; Henriksen, James R; Buchan, Alison; Reisch, Chris R; Bürgmann, Helmut; Welsh, Rory; Ye, Wenying; González, José M; Mace, Kimberly; Joye, Samantha B; Kiene, Ronald P; Whitman, William B; Moran, Mary Ann

    2006-10-27

    Flux of dimethylsulfide (DMS) from ocean surface waters is the predominant natural source of sulfur to the atmosphere and influences climate by aerosol formation. Marine bacterioplankton regulate sulfur flux by converting the precursor dimethylsulfoniopropionate (DMSP) either to DMS or to sulfur compounds that are not climatically active. Through the discovery of a glycine cleavage T-family protein with DMSP methyltransferase activity, marine bacterioplankton in the Roseobacter and SAR11 taxa were identified as primary mediators of DMSP demethylation to methylmercaptopropionate. One-third of surface ocean bacteria harbor a DMSP demethylase homolog and thereby route a substantial fraction of global marine primary production away from DMS formation and into the marine microbial food web.

  14. Exploring the aqueous vertical ionization of organic molecules by molecular simulation and liquid microjet photoelectron spectroscopy.

    PubMed

    Tentscher, Peter R; Seidel, Robert; Winter, Bernd; Guerard, Jennifer J; Arey, J Samuel

    2015-01-01

    To study the influence of aqueous solvent on the electronic energy levels of dissolved organic molecules, we conducted liquid microjet photoelectron spectroscopy (PES) measurements of the aqueous vertical ionization energies (VIEaq) of aniline (7.49 eV), veratrole alcohol (7.68 eV), and imidazole (8.51 eV). We also reanalyzed previously reported experimental PES data for phenol, phenolate, thymidine, and protonated imidazolium cation. We then simulated PE spectra by means of QM/MM molecular dynamics and EOM-IP-CCSD calculations with effective fragment potentials, used to describe the aqueous vertical ionization energies for six molecules, including aniline, phenol, veratrole alcohol, imidazole, methoxybenzene, and dimethylsulfide. Experimental and computational data enable us to decompose the VIEaq into elementary processes. For neutral compounds, the shift in VIE upon solvation, ΔVIEaq, was found to range from ≈-0.5 to -0.91 eV. The ΔVIEaq was further explained in terms of the influence of deforming the gas phase solute into its solution phase conformation, the influence of solute hydrogen-bond donor and acceptor interactions with proximate solvent molecules, and the polarization of about 3000 outerlying solvent molecules. Among the neutral compounds, variability in ΔVIEaq appeared largely controlled by differences in solute-solvent hydrogen-bonding interactions. Detailed computational analysis of the flexible molecule veratrole alcohol reveals that the VIE is strongly dependent on molecular conformation in both gas and aqueous phases. Finally, aqueous reorganization energies of the oxidation half-cell ionization reaction were determined from experimental data or estimated from simulation for the six compounds aniline, phenol, phenolate, veratrole alcohol, dimethylsulfide, and methoxybenzene, revealing a surprising constancy of 2.06 to 2.35 eV. PMID:25516011

  15. Does the odor from sponges of the genus Ircinia protect them from fish predators?

    PubMed

    Pawlik, Joseph R; McFall, Greg; Zea, Sven

    2002-06-01

    Caribbean sponges of the genus Ircinia contain high concentrations of linear furanosesterterpene tetronic acids (FTAs) and produce and exude low-molecular-weight volatile compounds (e.g., dimethyl sulfide, methyl isocyanide, methyl isothiocyanate) that give these sponges their characteristic unpleasant garlic odor. It has recently been suggested that FTAs are unlikely to function as antipredatory chemical defenses, and this function may instead be attributed to bioactive volatiles. We tested crude organic extracts and purified fractions isolated from Ircinia campana, I. felix, and I. strobilina at naturally occurring concentrations in laboratory and field feeding assays to determine their palatability to generalist fish predators. We also used a qualitative technique to test the crude volatile fraction from I. felix and I. strobilina and dimethylsulfide in laboratory feeding assays. Crude organic extracts of all three species deterred feeding of fishes in both aquarium and field experiments. Bioassay-directed fractionation resulted in the isolation of the FTA fraction as the sole active fraction of the nonvolatile crude extract for each species, and further assays of subfractions suggested that feeding deterrent activity is shared by the FTAs. FTAs deterred fish feeding in aquarium assays at concentrations as low as 0.5 mg/ml (fraction B, variabilin), while the natural concentrations of combined FTA fractions were > 5.0 mg/ml for all three species. In contrast, natural mixtures of volatiles transferred from sponge tissue to food pellets and pure dimethylsulfide incorporated into food pellets were readily eaten by fish in aquarium assays. Although FTAs may play other ecological roles in Ircinia spp., these compounds are effective as defenses against potential predatory fishes. Volatile compounds may serve other defensive functions (e.g., antimicrobial, antifouling) but do not appear to provide a defense against fish predators.

  16. L-methionine degradation potentialities of cheese-ripening microorganisms.

    PubMed

    Bonnarme, P; Lapadatescu, C; Yvon, M; Spinnler, H E

    2001-11-01

    Volatile sulphur compounds are major flavouring compounds in many traditional fermented foods including cheeses. These compounds are products of the catabolism of L-methionine by cheese-ripening microorganisms. The diversity of L-methionine degradation by such microorganisms, however, remains to be characterized. The objective of this work was to compare the capacities to produce volatile sulphur compounds by five yeasts, Geotrichum candidum, Yarrowia lipolytica, Kluyveromyces lactis, Debaryomyces hansenii, Saccharomyces cerevisiae and five bacteria, Brevibacterium linens, Corynebacterium glutamicum, Arthrobacter sp., Micrococcus lutens and Staphylococcus equorum of technological interest for cheese-ripening. The ability of whole cells of these microorganisms to generate volatile sulphur compounds from L-methionine was compared. The microorganisms produced a wide spectrum of sulphur compounds including methanethiol, dimethylsulfide, dimethyldisulfide, dimethyltrisulfide and also S-methylthioesters, which varied in amount and type according to strain. Most of the yeasts produced methanethiol, dimethylsulfide, dimethyldisulfide and dimethyltrisulfide but did not produce S-methylthioesters, apart from G. candidum that produced S-methyl thioacetate. Bacteria, especially Arth. sp. and Brevi. linens, produced the highest amounts and the greatest variety of volatile sulphur compounds includling methanethiol, sulfides and S-methylthioesters, e.g. S-methyl thioacetate, S-methyl thiobutyrate, S-methyl thiopropionate and S-methyl thioisovalerate. Cell-free extracts of all the yeasts and bacteria were examined for the activity of enzymes possibly involved in L-methionine catabolism, i.e. L-methionine demethiolase, L-methionine aminotransferase and L-methionine deaminase. They all possessed L-methionine demethiolase activity, while some (K. lactis, Deb. hansenii, Arth. sp., Staph. equorum) were deficient in L-methionine aminotransferase, and none produced L-methionine deaminase

  17. Global alteration of ocean ecosystem functioning due to increasing human CO2 emissions.

    PubMed

    Nagelkerken, Ivan; Connell, Sean D

    2015-10-27

    Rising anthropogenic CO2 emissions are anticipated to drive change to ocean ecosystems, but a conceptualization of biological change derived from quantitative analyses is lacking. Derived from multiple ecosystems and latitudes, our metaanalysis of 632 published experiments quantified the direction and magnitude of ecological change resulting from ocean acidification and warming to conceptualize broadly based change. Primary production by temperate noncalcifying plankton increases with elevated temperature and CO2, whereas tropical plankton decreases productivity because of acidification. Temperature increases consumption by and metabolic rates of herbivores, but this response does not translate into greater secondary production, which instead decreases with acidification in calcifying and noncalcifying species. This effect creates a mismatch with carnivores whose metabolic and foraging costs increase with temperature. Species diversity and abundances of tropical as well as temperate species decline with acidification, with shifts favoring novel community compositions dominated by noncalcifiers and microorganisms. Both warming and acidification instigate reduced calcification in tropical and temperate reef-building species. Acidification leads to a decline in dimethylsulfide production by ocean plankton, which as a climate gas, contributes to cloud formation and maintenance of the Earth's heat budget. Analysis of responses in short- and long-term experiments and of studies at natural CO2 vents reveals little evidence of acclimation to acidification or temperature changes, except for microbes. This conceptualization of change across whole communities and their trophic linkages forecast a reduction in diversity and abundances of various key species that underpin current functioning of marine ecosystems. PMID:26460052

  18. Evidence of methanesulfonate utilizers in the Sargasso Sea metagenome.

    PubMed

    Leitão, Elsa; Moradas-Ferreira, Pedro; De Marco, Paolo

    2009-09-01

    Methanesulfonate (MSA) is one of the products of the photo-oxidation of dimethylsulfide in the atmosphere. The genes responsible for the import of MSA into the cell (msm EFGH) and for its oxidation to formaldehyde (msm ABCD) have been previously sequenced from the soil bacterium Methylosulfonomonas methylovora str. M2 while genes for an MSA monooxygenase have been sequenced from marine bacterium Marinosulfonomonas methylotropha str. TR3. We performed a sequence-based screening of the Sargasso Sea metagenome for homologues of the MSA monooxygenase (MSAMO) and MSA import genes. Our search retrieved one scaffold bearing genes with high identity to the msm ABCD cluster plus two scaffolds bearing genes highly identical to the msm EFGH operon. We increased the available data by sequencing two metagenome plasmids, which revealed more msm genes. In these three cases synteny with the original msm operons was revealed. We also retrieved several singletons showing high identity to shorter segments of the msm clusters or individual msm genes. Furthermore, a characteristic 26-aa internal spacer of the MsmA Rieske-type motif was conserved. Our findings support the case for a significant role of MSA degraders in the marine sulfur cycle and seem to suggest that they may be prominent members of the methylotrophic community in surface ocean waters.

  19. Environmental, biochemical and genetic drivers of DMSP degradation and DMS production in the Sargasso Sea.

    PubMed

    Levine, Naomi Marcil; Varaljay, Vanessa A; Toole, Dierdre A; Dacey, John W H; Doney, Scott C; Moran, Mary Ann

    2012-05-01

    Dimethylsulfide (DMS) is a climatically relevant trace gas produced and cycled by the surface ocean food web. Mechanisms driving intraannual variability in DMS production and dimethylsulfoniopropionate (DMSP) degradation in open-ocean, oligotrophic regions were investigated during a 10-month time-series at the Bermuda Atlantic Time-series Study site in the Sargasso Sea. Abundance and transcription of bacterial DMSP degradation genes, DMSP lyase enzyme activity, and DMS and DMSP concentrations, consumption rates and production rates were quantified over time and depth. This interdisciplinary data set was used to test current hypotheses of the role of light and carbon supply in regulating upper-ocean sulfur cycling. Findings supported UV-A-dependent phytoplankton DMS production. Bacterial DMSP degraders may also contribute significantly to DMS production when temperatures are elevated and UV-A dose is moderate, but may favour DMSP demethylation under low UV-A doses. Three groups of bacterial DMSP degraders with distinct intraannual variability were identified and niche differentiation was indicated. The combination of genetic and biochemical data suggest a modified 'bacterial switch' hypothesis where the prevalence of different bacterial DMSP degradation pathways is regulated by a complex set of factors including carbon supply, temperature and UV-A dose.

  20. Diversity of bacterial dimethylsulfoniopropionate degradation genes in surface seawater of Arctic Kongsfjorden.

    PubMed

    Zeng, Yin-Xin; Qiao, Zong-Yun; Yu, Yong; Li, Hui-Rong; Luo, Wei

    2016-01-01

    Dimethylsulfoniopropionate (DMSP), which is the major source of organic sulfur in the world's oceans, plays a significant role in the global sulfur cycle. This compound is rapidly degraded by marine bacteria either by cleavage to dimethylsulfide (DMS) or demethylation to 3-methylmercaptopropionate (MMPA). The diversity of genes encoding bacterial demethylation (dmdA) and DMS production (dddL and dddP) were measured in Arctic Kongsfjorden. Both dmdA and dddL genes were detected in all stations along a transect from the outer to the inner fjord, while dddP gene was only found in the outer and middle parts of the fjord. The dmdA gene was completely confined to the Roseobacter clade, while the dddL gene was confined to the genus Sulfitobacter. Although the dddP gene pool was also dominated by homologs from the Roseobacter clade, there were a few dddP genes showing close relationships to both Alphaproteobacter and Gammaproteobacter. The results of this study suggest that the Roseobacter clade may play an important role in DMSP catabolism via both demethylation and cleavage pathways in surface waters of Kongsfjorden during summer. PMID:27604458

  1. Key changes in wine aroma active compounds during bottle storage of Spanish red wines under different oxygen levels.

    PubMed

    Ferreira, Vicente; Bueno, Mónica; Franco-Luesma, Ernesto; Culleré, Laura; Fernández-Zurbano, Purificación

    2014-10-15

    Samples from 16 Spanish red wines have been stored for 6 months at 25 °C under different levels of oxygen (0-56 mg/L). Amino acids, metals, and phenolic compounds were analyzed and related to the production or depletion of key oxidation- and reduction-related aroma compounds. Oxidation brings about sensory-relevant increases in Strecker aldehydes, 1-octen-3-one, and vanillin. Formation of Strecker aldehydes correlates to the wine content on the corresponding amino acid precursor, Zn, and caffeic acid ethyl ester and negatively to some flavonols and anthocyanin derivatives. Formation of most carbonyls correlates to wine-combined SO2, suggesting that part of the increments are the result of the release of aldehydes forming bisulfite combinations once SO2 is oxidized. Methanethiol (MeSH) and dimethylsulfide (DMS), but not H2S levels, increase during storage. MeSH increments correlate to methionine levels and proanthocyanidins and negatively to resveratrol and aluminum. H2S, MeSH, and DMS levels all decreased with oxidation, and for the latter two, there are important effects of Mn and pH, respectively.

  2. [Effect of design and operation parameters on volatile alkylsulfides removal in subsurface constructed wetlands].

    PubMed

    Feng, Lin; Gan, Li; Wang, Hua-jie; Mo, Ping; Huang, Yu-ming

    2010-02-01

    A pilot-scale subsurface constructed wetland wastewater treatment system was sampled for one year to study the effects of bed aspect ratio, substrate medium size, water depth, HLR (hydraulic loading rate) and temperature (season) on removal of volatile alkylsulfides such as DMS (dimethylsulfide) and DMDS (dimethyldisulfide). The yearly experimental results demonstrated that the system showed good performance for DMS and DMDS removal in wastewater under different HLR ranging from 12 cm x d(-1) to 86 cm x d(-1). The system could remove 86% of DMS, and 95% of DMDS, respectively. ANOVA statistical analysis shows that HLR and temperature (season) are major factors controlling the system performance for the target analytes. According to ANOVA test, the HLR caused significant differences (p < 0.01) on the average DMS effluent concentrations, and temperature (season) caused significant differences (p < 0.01) on the average DMS and DMDS effluent concentrations. However, bed aspect ratio, substrate medium size and water depth did not cause significant differences (p > 0.05) on the average DMS and DMDS effluent concentrations. A survey of dissolved oxygen and ORP indicates that the constructed wetlands system showed strong reduced condition. On the basis of investigations of electron acceptors (such as SO4(2-), NO3- and NO2-) and dissolved organic pollutants (such as TOC and acetic acid) concentrations along with the length of constructed wetlands, it can be concluded that sulfate reduction and methanogenisis were estimated to be significant for DMS and DMDS removal in constructed wetland beds. PMID:20391700

  3. Flavoromics approach in monitoring changes in volatile compounds of virgin rapeseed oil caused by seed roasting.

    PubMed

    Gracka, Anna; Jeleń, Henryk H; Majcher, Małgorzata; Siger, Aleksander; Kaczmarek, Anna

    2016-01-01

    Two varieties of rapeseed (one high oleic - containing 76% of oleic acid, and the other - containing 62% of oleic acid) were used to produce virgin (pressed) oil. The rapeseeds were roasted at different temperature/time combinations (at 140-180°C, and for 5-15min); subsequently, oil was pressed from the roasted seeds. The roasting improved the flavour and contributed to a substantial increase in the amount of a potent antioxidant-canolol. The changes in volatile compounds related to roasting conditions were monitored using comprehensive gas chromatography-mass spectrometry (GC×GC-ToFMS), and the key odorants for the non-roasted and roasted seeds oils were determined by gas chromatography-olfactometry (GC-O). The most important compounds determining the flavour of oils obtained from the roasted seeds were dimethyl sulphide, dimethyltrisulfide, 2,3-diethyl-5-methylpyrazine, 2,3-butenedione, octanal, 3-isopropyl-2-methoxypyrazine and phenylacetaldehyde. For the oils obtained from the non-roasted seeds, the dominant compounds were dimethylsulfide, hexanal and octanal. Based on GC×GC-ToFMS and principal component analysis (PCA) of the data, several compounds were identified that were associated with roasting at the highest temperatures regardless of the rapeseed variety: these were, among others, methyl ketones (2-hexanone, 2-heptanone and 2-octanone).

  4. Laser flash photolysis studies of atmospheric free radical chemistry using optical diagnostic techniques

    NASA Technical Reports Server (NTRS)

    Wine, Paul H.; Nicovich, J. M.; Hynes, Anthony J.; Stickel, Robert E.; Thorn, R. P.; Chin, Mian; Cronkhite, Jeffrey A.; Shackelford, Christie J.; Zhao, Zhizhong; Daykin, Edward P.

    1993-01-01

    Some recent studies carried out in our laboratory are described where laser flash photolytic production of reactant free radicals has been combined with reactant and/or product detection using time-resolved optical techniques to investigate the kinetics and mechanisms of important atmospheric chemical reactions. Discussed are (1) a study of the radical-radical reaction O + BrO yields Br + O2 where two photolysis lasers are employed to prepare the reaction mixture and where the reactants O and BrO are monitored simultaneously using atomic resonance fluorescence to detect O and multipass UV absorption to detect BrO; (2) a study of the reaction of atomic chlorine with dimethylsulfide (CH3SCH3) where atomic resonance fluorescence detection of Cl is employed to elucidate the kinetics and tunable diode laser absorption spectroscopy is employed to investigate the HCl product yield; and (3) a study of the aqueous phase chemistry of Cl2(-) radicals where longpath UV absorption spectroscopy is employed to investigate the kinetics of the Cl2(-) + H2O reaction.

  5. Production of Molecular Iodine and Tri-iodide in the Frozen Solution of Iodide: Implication for Polar Atmosphere.

    PubMed

    Kim, Kitae; Yabushita, Akihiro; Okumura, Masanori; Saiz-Lopez, Alfonso; Cuevas, Carlos A; Blaszczak-Boxe, Christopher S; Min, Dae Wi; Yoon, Ho-Il; Choi, Wonyong

    2016-02-01

    The chemistry of reactive halogens in the polar atmosphere plays important roles in ozone and mercury depletion events, oxidizing capacity, and dimethylsulfide oxidation to form cloud-condensation nuclei. Among halogen species, the sources and emission mechanisms of inorganic iodine compounds in the polar boundary layer remain unknown. Here, we demonstrate that the production of tri-iodide (I3(-)) via iodide oxidation, which is negligible in aqueous solution, is significantly accelerated in frozen solution, both in the presence and the absence of solar irradiation. Field experiments carried out in the Antarctic region (King George Island, 62°13'S, 58°47'W) also showed that the generation of tri-iodide via solar photo-oxidation was enhanced when iodide was added to various ice media. The emission of gaseous I2 from the irradiated frozen solution of iodide to the gas phase was detected by using cavity ring-down spectroscopy, which was observed both in the frozen state at 253 K and after thawing the ice at 298 K. The accelerated (photo-)oxidation of iodide and the subsequent formation of tri-iodide and I2 in ice appear to be related with the freeze concentration of iodide and dissolved O2 trapped in the ice crystal grain boundaries. We propose that an accelerated abiotic transformation of iodide to gaseous I2 in ice media provides a previously unrecognized formation pathway of active iodine species in the polar atmosphere. PMID:26745029

  6. Measurement of gas/water uptake coefficients for trace gases active in the marine environment. [Annual report

    SciTech Connect

    Davidovits, P.; Worsnop, D.W.; Zahniser, M.S.; Kolb, C.E.

    1992-02-01

    Ocean produced reduced sulfur compounds including dimethylsulfide (DMS), hydrogen sulfide (H{sub 2}S), carbon disulfide (CS{sub 2}), methyl mercaptan (CH{sub 3}CH) and carbonyl sulfide (OCS) deliver a sulfur burden to the atmosphere which is roughly equal to sulfur oxides produced by fossil fuel combustion. These species and their oxidation products dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO{sub 2}) and methane sulfonic acid (MSA) dominate aerosol and CCN production in clean marine air. Furthermore, oxidation of reduced sulfur species will be strongly influenced by NO{sub x}/O{sub 3} chemistry in marine atmospheres. The multiphase chemical processes for these species must be understood in order to study the evolving role of combustion produced sulfur oxides over the oceans. We have measured the chemical and physical parameters affecting the uptake of reduced sulfur compounds, their oxidation products, ozone, and nitrogen oxides by the ocean`s surface, and marine clouds, fogs, and aerosols. These parameters include: gas/surface mass accommodation coefficients; physical and chemically modified (effective) Henry`s law constants; and surface and liquid phase reaction constants. These parameters are critical to understanding both the interaction of gaseous trace species with cloud and fog droplets and the deposition of trace gaseous species to dew covered, fresh water and marine surfaces.

  7. Measurement of gas/water uptake coefficients for trace gases active in the marine environment

    SciTech Connect

    Davidovits, P. . Dept. of Chemistry); Worsnop, D.W.; Zahniser, M.S.; Kolb, C.E. . Center for Chemical and Environmental Physics)

    1992-02-01

    Ocean produced reduced sulfur compounds including dimethylsulfide (DMS), hydrogen sulfide (H{sub 2}S), carbon disulfide (CS{sub 2}), methyl mercaptan (CH{sub 3}CH) and carbonyl sulfide (OCS) deliver a sulfur burden to the atmosphere which is roughly equal to sulfur oxides produced by fossil fuel combustion. These species and their oxidation products dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO{sub 2}) and methane sulfonic acid (MSA) dominate aerosol and CCN production in clean marine air. Furthermore, oxidation of reduced sulfur species will be strongly influenced by NO{sub x}/O{sub 3} chemistry in marine atmospheres. The multiphase chemical processes for these species must be understood in order to study the evolving role of combustion produced sulfur oxides over the oceans. We have measured the chemical and physical parameters affecting the uptake of reduced sulfur compounds, their oxidation products, ozone, and nitrogen oxides by the ocean's surface, and marine clouds, fogs, and aerosols. These parameters include: gas/surface mass accommodation coefficients; physical and chemically modified (effective) Henry's law constants; and surface and liquid phase reaction constants. These parameters are critical to understanding both the interaction of gaseous trace species with cloud and fog droplets and the deposition of trace gaseous species to dew covered, fresh water and marine surfaces.

  8. Prey-dependent retention of dimethylsulfoniopropionate (DMSP) by mixotrophic dinoflagellates

    PubMed Central

    Lee, Hyunwoo; Park, Ki-Tae; Lee, Kitack; Jeong, Hae Jin; Yoo, Yeong Du

    2012-01-01

    Summary We investigated the retention of dimethylsulfoniopropionate (DMSP) in phototrophic dinoflagellates arising from mixotrophy by estimating the cellular content of DMSP in Karlodinium veneficum (mixotrophic growth) fed for 7–10 days on either DMSP-rich Amphidinium carterae (phototrophic growth only) or DMSP-poor Teleaulax sp. (phototrophic growth only). In K. veneficum fed on DMSP-poor prey, the cellular content of DMSP remained almost unchanged regardless of the rate of feeding, whereas the cellular content of DMSP in cells of K. veneficum fed on DMSP-rich prey increased by as much as 21 times the cellular concentration derived exclusively from phototrophic growth. In both cases, significant fractions (10–32% in the former case and 55–65% in the latter) of the total DMSP ingested by K. veneficum were transformed into dimethylsulfide and other biochemical compounds. The results may indicate that the DMSP content of prey species affects temporal variations in the cellular DMSP content of mixotrophic dinoflagellates, and that mixotrophic dinoflagellates produce DMS through grazing on DMSP-rich preys. Additional studies should be performed to examine the universality of our finding in other mixotrophic dinoflagellates feeding on diverse prey species. PMID:21958033

  9. How phosphorus limitation can control climatic gas emission

    NASA Astrophysics Data System (ADS)

    Gypens, Nathalie; Borges, Alberto V.; Speeckaert, Gaelle; Ghyoot, Caroline

    2015-04-01

    Anthropogenic activities severely increased river nutrient [nitrogen (N) and phosphorus (P)] loads to European coastal areas. However, specific nutrient reduction policies implemented since the late 1990's have considerably reduced P loads, while N is maintained. In the Southern North Sea, the resulting N: P: Si imbalance (compared to phytoplankton requirements) stimulated the growth of Phaeocystis colonies modifying the functioning of the ecosystem and, therefore, the carbon cycle but also the biogenic sulphur cycle, Phaeocystis being a significant producer of DMSP (dimethylsulphide propionate), the precursor of dimethylsulfide (DMS). In this application, the mechanistic MIRO-BIOGAS model is used to investigate the effects of changing N and P loads on ecosystem structure and their impact on DMS and CO2 emissions. In particular, competition for P between phytoplankton groups (diatoms vs Phaeocystis colonies) but also between phytoplankton and bacteria is explored. The ability of autotroph and heterotroph organism to use dissolved organic phosphorus (DOP) as P nutrient source is also explored and its effect on climatic gas emission estimated. Simulations were done from 1950 to 2010 and different nutrient limiting conditions are analyzed.

  10. A modelling study of the atmospheric chemistry of DMS using the global model, STOCHEM-CRI

    NASA Astrophysics Data System (ADS)

    Khan, M. A. H.; Gillespie, S. M. P.; Razis, B.; Xiao, P.; Davies-Coleman, M. T.; Percival, C. J.; Derwent, R. G.; Dyke, J. M.; Ghosh, M. V.; Lee, E. P. F.; Shallcross, D. E.

    2016-02-01

    The tropospheric chemistry of dimethylsulfide (DMS) is investigated using a global three-dimensional chemical transport model, STOCHEM with the CRIv2-R5 chemistry scheme. The tropospheric distribution of DMS and its removal at the surface by OH abstraction, OH addition, NO3 oxidation, and BrO oxidation is modelled. The study shows that the lifetime and global burden of DMS is ca. 1.2 days and 98 Gg S, respectively. Inclusion of BrO oxidation resulted in a reduction of the lifetime (1.0 day) and global burden (83 Gg S) of DMS showing that this reaction is important in the DMS budget. The percentage contribution of BrO oxidation to the total removal of DMS is found to be only 7.9% that is considered a lower limit because the study does not include an inorganic source of bromine from sea-salt. BrO oxidation contributed significantly in the high latitudes of the southern hemisphere (SH). Inclusion of DMS removal by Cl2 showed that potentially a large amount of DMS is removed via this reaction specifically in the remote SH oceans, depending on the flux of Cl2 from the Southern Ocean. Model DMS levels are evaluated against measurement data from six different sites around the globe. The model predicted the correct seasonal cycle for DMS at all locations and correlated well with measurement data for most of the periods.

  11. Link Between Enhanced Arctic Tropospheric BrO Observed By Aura OMI and Meteorological Conditions

    NASA Astrophysics Data System (ADS)

    Choi, S.; Joiner, J.; Salawitch, R. J.; Canty, T. P.; Theys, N.; da Silva, A.; Chance, K.; Suleiman, R. M.; Kurosu, T. P.

    2014-12-01

    Bromine radicals (Br + BrO) are important species owing to the ability to destroy ozone catalytically. They may also impact oxidative pathways of many trace gases including dimethylsulfide (DMS) and mercury. Bromine monoxide (BrO) is the most commonly observed bromine radical species. Since it absorbs ultraviolet (UV) radiation, it can be observed using remote sensing technique including Differential Optical Absorption Spectroscopy (DOAS). Previous studies have reported rapid enhancements tropospheric BrO (so called "BrO explosion") connected to near-surface ozone depletion events during springtime in the Arctic. Space-based observation of BrO through Ozone Monitoring Instrument (OMI) is an excellent tool for studying bromine chemistry particularly for the Arctic due to its frequent observations at high latitudes. We derive tropospheric columns BrO by subtracting estimates of stratospheric column BrO from OMI total column BrO and air mass factor (AMF) correction, and analyze the tropospheric columns BrO in conjunction with Modern-Era Retrospective analysis for Research and Application (MERRA) meteorological fields provided by NASA Global Modeling and Assimilation Office (GMAO) in order to investigate a link between BrO explosion and near-surface meteorological factors.

  12. Link between Enhanced Arctic tropospheric BrO observed by Aura OMI and meteorological conditions

    NASA Astrophysics Data System (ADS)

    Choi, S.; Joiner, J.; Theys, N.; Salawitch, R. J.; Wales, P.; Canty, T. P.; Chance, K.; Suleiman, R. M.; Palm, S. P.; Cullather, R. I.; Darmenov, A.; da Silva, A.; Kurosu, T. P.

    2015-12-01

    Bromine radicals (Br + BrO) are important species owing to the ability to destroy ozone catalytically. They may also impact oxidative pathways of many trace gases including dimethylsulfide (DMS) and mercury. Bromine monoxide (BrO) is the most commonly observed bromine radical species. Since it absorbs ultraviolet (UV) radiation, it can be observed using remote sensing technique including Differential Optical Absorption Spectroscopy (DOAS). Previous studies have reported rapid enhancements tropospheric BrO (so called "bromine explosion") connected to near-surface ozone depletion events during springtime in the Arctic. Space-based observation of BrO through Ozone Monitoring Instrument (OMI) is an excellent tool for studying bromine chemistry particularly for the Arctic due to its frequent observations at high latitudes. We derive tropospheric columns BrO by subtracting estimates of stratospheric column BrO from OMI total column BrO and air mass factor (AMF) correction, and analyze the tropospheric columns BrO in conjunction with Modern-Era Retrospective analysis for Research and Application (MERRA) meteorological fields provided by NASA Global Modeling and Assimilation Office (GMAO) in order to investigate a link between bromine explosion and near-surface meteorological factors.

  13. Environmental, biochemical and genetic drivers of DMSP degradation and DMS production in the Sargasso Sea.

    PubMed

    Levine, Naomi Marcil; Varaljay, Vanessa A; Toole, Dierdre A; Dacey, John W H; Doney, Scott C; Moran, Mary Ann

    2012-05-01

    Dimethylsulfide (DMS) is a climatically relevant trace gas produced and cycled by the surface ocean food web. Mechanisms driving intraannual variability in DMS production and dimethylsulfoniopropionate (DMSP) degradation in open-ocean, oligotrophic regions were investigated during a 10-month time-series at the Bermuda Atlantic Time-series Study site in the Sargasso Sea. Abundance and transcription of bacterial DMSP degradation genes, DMSP lyase enzyme activity, and DMS and DMSP concentrations, consumption rates and production rates were quantified over time and depth. This interdisciplinary data set was used to test current hypotheses of the role of light and carbon supply in regulating upper-ocean sulfur cycling. Findings supported UV-A-dependent phytoplankton DMS production. Bacterial DMSP degraders may also contribute significantly to DMS production when temperatures are elevated and UV-A dose is moderate, but may favour DMSP demethylation under low UV-A doses. Three groups of bacterial DMSP degraders with distinct intraannual variability were identified and niche differentiation was indicated. The combination of genetic and biochemical data suggest a modified 'bacterial switch' hypothesis where the prevalence of different bacterial DMSP degradation pathways is regulated by a complex set of factors including carbon supply, temperature and UV-A dose. PMID:22324779

  14. Transcriptomic analysis of a marine bacterial community enriched with dimethylsulfoniopropionate.

    PubMed

    Vila-Costa, Maria; Rinta-Kanto, Johanna M; Sun, Shulei; Sharma, Shalabh; Poretsky, Rachel; Moran, Mary Ann

    2010-11-01

    Dimethylsulfoniopropionate (DMSP) is an important source of reduced sulfur and carbon for marine microbial communities, as well as the precursor of the climate-active gas dimethylsulfide (DMS). In this study, we used metatranscriptomic sequencing to analyze gene expression profiles of a bacterial assemblage from surface waters at the Bermuda Atlantic Time-series Study (BATS) station with and without a short-term enrichment of DMSP (25 nM for 30 min). An average of 303 143 reads were obtained per treatment using 454 pyrosequencing technology, of which 51% were potential protein-encoding sequences. Transcripts from Gammaproteobacteria and Bacteroidetes increased in relative abundance on DMSP addition, yet there was little change in the contribution of two bacterioplankton groups whose cultured members harbor known DMSP degradation genes, Roseobacter and SAR11. The DMSP addition led to an enrichment of transcripts supporting heterotrophic activity, and a depletion of those encoding light-related energy generation. Genes for the degradation of C3 compounds were significantly overrepresented after DMSP addition, likely reflecting the metabolism of the C3 component of DMSP. Mapping these transcripts to known biochemical pathways indicated that both acetyl-CoA and succinyl-CoA may be common entry points of this moiety into the tricarboxylic acid cycle. In a short time frame (30 min) in the extremely oligotrophic Sargasso Sea, different gene expression patterns suggest the use of DMSP by a diversity of marine bacterioplankton as both carbon and sulfur sources. PMID:20463763

  15. The reduced flavin-dependent monooxygenase SfnG converts dimethylsulfone to methanesulfinate.

    PubMed

    Wicht, Denyce K

    2016-08-15

    The biochemical pathway through which sulfur may be assimilated from dimethylsulfide (DMS) is proposed to proceed via oxidation of DMS to dimethylsulfoxide (DMSO) and subsequent conversion of DMSO to dimethylsulfone (DMSO2). Analogous chemical oxidation processes involving biogenic DMS in the atmosphere result in the deposition of DMSO2 into the terrestrial environment. Elucidating the enzymatic pathways that involve DMSO2 contribute to our understanding of the global sulfur cycle. Dimethylsulfone monooxygenase SfnG and flavin mononucleotide (FMN) reductase MsuE from the genome of the aerobic soil bacterium Pseudomonas fluorescens Pf0-1 were produced in Escherichia coli, purified, and biochemically characterized. The enzyme MsuE functions as a reduced nicotinamide adenine dinucleotide (NADH)-dependent FMN reductase with apparent steady state kinetic parameters of Km = 69 μM and kcat/Km = 9 min(-1) μM (-1) using NADH as the variable substrate, and Km = 8 μM and kcat/Km = 105 min(-1) μM (-1) using FMN as the variable substrate. The enzyme SfnG functions as a flavoprotein monooxygenase and converts DMSO2 to methanesulfinate in the presence of FMN, NADH, and MsuE, as evidenced by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy. The results suggest that methanesulfinate is a biochemical intermediate in sulfur assimilation. PMID:27392454

  16. The atmospheric sulfur cycle over the Amazon Basin. II - Wet season

    NASA Technical Reports Server (NTRS)

    Andreae, M. O.; Bingemer, H.; Berresheim, H.; Jacob, D. J.; Lewis, B. L.

    1990-01-01

    The fluxes and concentrations of atmospheric sulfur species were determined at ground level and from aircraft over the Amazon Basin during the 1987 wet season, providing a comprehensive description of the sulfur cycle over a remote tropical region. The vertical profile of dimethylsulfide (DMS) during the wet season was found to be very similar to that measured during the dry season, suggesting little seasonal variation in DMS fluxes. The concentrations of H2S were almost an order of magnitude higher than those of DMS, which makes H2S the most important biogenic source species in the atmosheric sulfur cycle over the Amazon Basin. Using the gradient-flux approach, the flux of DMS at the top of the tree canopy was estimated. The canopy was a source of DMS during the day, and a weak sink during the night. Measurements of sulfur gas emissions from soils, using the chamber method, showed very small fluxes, consistent with the hypothesis that the forest canopy is the major source of sulfur gases. The observed soil and canopy emission fluxes are similar to those measured in temperate regions. The concentrations of SO2 and sulfate aerosol in the wet season atmosphere were similar to dry season values.

  17. Global alteration of ocean ecosystem functioning due to increasing human CO2 emissions

    PubMed Central

    Nagelkerken, Ivan; Connell, Sean D.

    2015-01-01

    Rising anthropogenic CO2 emissions are anticipated to drive change to ocean ecosystems, but a conceptualization of biological change derived from quantitative analyses is lacking. Derived from multiple ecosystems and latitudes, our metaanalysis of 632 published experiments quantified the direction and magnitude of ecological change resulting from ocean acidification and warming to conceptualize broadly based change. Primary production by temperate noncalcifying plankton increases with elevated temperature and CO2, whereas tropical plankton decreases productivity because of acidification. Temperature increases consumption by and metabolic rates of herbivores, but this response does not translate into greater secondary production, which instead decreases with acidification in calcifying and noncalcifying species. This effect creates a mismatch with carnivores whose metabolic and foraging costs increase with temperature. Species diversity and abundances of tropical as well as temperate species decline with acidification, with shifts favoring novel community compositions dominated by noncalcifiers and microorganisms. Both warming and acidification instigate reduced calcification in tropical and temperate reef-building species. Acidification leads to a decline in dimethylsulfide production by ocean plankton, which as a climate gas, contributes to cloud formation and maintenance of the Earth’s heat budget. Analysis of responses in short- and long-term experiments and of studies at natural CO2 vents reveals little evidence of acclimation to acidification or temperature changes, except for microbes. This conceptualization of change across whole communities and their trophic linkages forecast a reduction in diversity and abundances of various key species that underpin current functioning of marine ecosystems. PMID:26460052

  18. Immobilized organic photosensitizers with versatile reactivity for various visible-light applications.

    PubMed

    Ronzani, Filippo; Saint-Cricq, Philippe; Arzoumanian, Emmanuel; Pigot, Thierry; Blanc, Sylvie; Oelgemöller, Michael; Oliveros, Esther; Richard, Claire; Lacombe, Sylvie

    2014-01-01

    Various photosensitizers were grafted by conventional peptide coupling methods to functionalized silica with several macroscopic shapes (powders, films) or embedded in highly transparent and microporous silica xerogel monoliths. Owing to the transparency and free-standing shape of the monoliths, the transient species arising from irradiation of the PSs could be analyzed and were not strikingly different from those observed in solutions. The observed reactivity for either liquid-solid (α-terpinene oxygenation vs dehydrogenation) or gas-solid (dimethylsulfide, DMS, solvent-free oxidation) reactions was consistent with the properties of the excited states of the PSs under consideration. Immobilized anthraquinone-derived materials preferentially react in both cases by electron transfer from the substrate to the triplet state of the sensitizer, in spite of an efficient singlet oxygen production. The recently developed 9,14-dicyanobenzo[b]triphenylene-3-carboxylic acid, DBTP-COOH, efficiently reacts via energy transfer to yield singlet oxygen from its triplet state. It was shown to perform better than 9,10-dicyanoanthracene and rose bengal for DMS oxidation and α-terpinene photooxygenation to ascaridole, respectively. Thus, by a proper choice of the organic immobilized photocatalyst, it is possible to develop efficient and reusable materials, activated under visible light, for various applications and to tune the reaction pathway, opening the way to green oxidation processes. PMID:24033260

  19. Variations in the methanesulfonate to sulfate molar ratio in submicrometer marine aerosol particles over the south Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Bates, Timothy S.; Calhoun, Julie A.; Quinn, Patricia K.

    1992-01-01

    Seawater concentrations of dimethylsulfide (DMS) and atmospheric concentrations of DMS, sulfur dioxide, methanesulfonate (MSA), and non-sea-salt (nss) sulfate were measured over the eastern Pacific Ocean between 105 deg and 110 deg W from 20 deg N to 60 deg S during February and March 1989. Although the samples collected in the Southern Hemisphere appear to be of marine origin, no significant correlation was found between the latitudinal distributions of DMS, SO2, MSA, and nss SO4(2-). However, an inverse correlation was found between atmospheric temperature and the MSA to nss SO4(2-) molar ratio in submicrometer aerosol particles with a decrease in temperature corresponding to an increase in the molar ratio. Although this trend is consistent with laboratory results indicating the favored production of MSA at lower temperatures, it is contrary to Southern Hemisphere baseline station data. This suggests either a decrease in the supply of DMS relative to nonmarine sources of nss SO4(2-) at the baseline stations in winter or additional mechanisms that affect the relative production of MSA and nss SO4(2-).

  20. Global alteration of ocean ecosystem functioning due to increasing human CO2 emissions.

    PubMed

    Nagelkerken, Ivan; Connell, Sean D

    2015-10-27

    Rising anthropogenic CO2 emissions are anticipated to drive change to ocean ecosystems, but a conceptualization of biological change derived from quantitative analyses is lacking. Derived from multiple ecosystems and latitudes, our metaanalysis of 632 published experiments quantified the direction and magnitude of ecological change resulting from ocean acidification and warming to conceptualize broadly based change. Primary production by temperate noncalcifying plankton increases with elevated temperature and CO2, whereas tropical plankton decreases productivity because of acidification. Temperature increases consumption by and metabolic rates of herbivores, but this response does not translate into greater secondary production, which instead decreases with acidification in calcifying and noncalcifying species. This effect creates a mismatch with carnivores whose metabolic and foraging costs increase with temperature. Species diversity and abundances of tropical as well as temperate species decline with acidification, with shifts favoring novel community compositions dominated by noncalcifiers and microorganisms. Both warming and acidification instigate reduced calcification in tropical and temperate reef-building species. Acidification leads to a decline in dimethylsulfide production by ocean plankton, which as a climate gas, contributes to cloud formation and maintenance of the Earth's heat budget. Analysis of responses in short- and long-term experiments and of studies at natural CO2 vents reveals little evidence of acclimation to acidification or temperature changes, except for microbes. This conceptualization of change across whole communities and their trophic linkages forecast a reduction in diversity and abundances of various key species that underpin current functioning of marine ecosystems.

  1. Climate regulation by marine phytoplankton. : A test by anthropogenic SO/sub 2/ emissions

    SciTech Connect

    Schwartz, S.E.

    1989-05-01

    The potential sensitivity of global mean albedo and temperature to N prompted a novel suggestion consistent with the Gaia hypothesis for regulation of global climate by marine phytoplankton. Certain species of coccolithophores excrete dimethylsulfide (DMS), and this DMS is arguably the principal source of reduced sulfur gases in the global atmosphere and, in the absence of anthropogenic SO/sub 2/, the principal source of atmospheric gaseous sulfur species. Such gaseous sulfur species are oxidized in the atmosphere to form sulfuric acid, which rapidly forms an aerosol. Since sulfate-containing AP are highly efficient CCN, it is argued that an increase in DMS production by marine phytoplankton would yield increased concentrations of CCN, resulting in increased cloud albedo, decreased surface insolation, and decreased planetary temperature. It is further hypothesized that such decreased insolation or temperature might result in decreased production of DMS by marine phytoplankton, i.e., that the process might constitute a negative feedback loop for regulation of planetary climate by marine microorganisms. 18 refs., 3 figs., 1 tab.

  2. Possible biogeochemical consequences of ocean fertilization

    SciTech Connect

    Fuhrman, J.A. ); Capone, D.G. )

    1991-12-01

    The authors consider biogeochemical secondary effects that could arise from an increase in ocean productivity, such as may occur via fertilization with Fe. These processes and feedback loops are infrequently discussed in this context, yet are likely to be highly relevant to the understanding of global change in general. In particular, the authors suggest that increased productivity may increase the production and efflux of greenhouse gases, such as nitrous oxide (N{sub 2}O) and methane (CH{sub 4}) and that shifts in phytoplankton species and productivity may cause changes in another climate-related gas, dimethylsulfide (DMS). N{sub 2}O is also implicated in the destruction of stratospheric ozone. Factors contributing to amplified release include both increased nutrient cycling in general and possible development of low oxygen conditions from fertilization. It is also remotely possible that reduced oxygen from an initial fertilization could mobilize existing Fe pools, inducing uncontrolled self-fertilization. Although lack of relevant physiological and ecological data makes it difficult to provide quantitative limits on the extent of the undesired effects, rough calculations suggest that the enhanced release of N{sub 2}O alone could totally negate any potential benefit from fertilization and likely worsen global warming and ozone depletion.

  3. Airborne observations of DMSO, DMS, and OH at marine tropical latitudes

    NASA Astrophysics Data System (ADS)

    Nowak, J. B.; Davis, D. D.; Chen, G.; Eisele, F. L.; Mauldin, R. L., III; Tanner, D. J.; Cantrell, C.; Kosciuch, E.; Bandy, A.; Thornton, D.; Clarke, A.

    This paper reports the first simultaneous fast-time resolution measurements of dimethylsulfide (DMS), dimethylsulfoxide (DMSO), and the hydroxyl radical (OH) at marine tropical latitudes. These observations were recorded during the PEM-Tropics B field program on NASA's P-3B aircraft. The observations of DMSO, using a Selected Ion Chemical Ionization Mass Spectrometry (SICIMS) technique, are of particular significance. They have revealed two unique findings: 1) average midday-tropical levels of DMSO are significantly higher than those predicted from current models when constrained by observed DMS and OH levels (e.g., 10 pptv versus 1 to 3 pptv); and 2) DMSO concentration profiles are significantly out-of-phase with model predictions, maximum values being seen under near dark conditions and minimum values being observed at midday. Although no simple explanation has yet been found for these unusual results, the fact that no evidence points to a problem in the measurements suggests that others may exist. Clearly, if the observations are correct, they indicate that at least for tropical upwelling regions the atmospheric sulfur budget may need to be adjusted to accommodate additional sources of DMSO.

  4. Linking TFT-LCD wastewater treatment performance to microbial population abundance of Hyphomicrobium and Thiobacillus spp.

    PubMed

    Fukushima, Toshikazu; Whang, Liang-Ming; Chen, Po-Chun; Putri, Dyah Wulandari; Chang, Ming-Yu; Wu, Yi-Ju; Lee, Ya-Ching

    2013-08-01

    This study investigated the linkage between performance of two full-scale membrane bioreactor (MBR) systems treating thin-film transistor liquid crystal display (TFT-LCD) wastewater and the population dynamics of dimethylsulfoxide (DMSO)/dimethylsulfide (DMS) degrading bacteria. High DMSO degradation efficiencies were achieved in both MBRs, while the levels of nitrification inhibition due to DMS production from DMSO degradation were different in the two MBRs. The results of real-time PCR targeting on DMSO/DMS degrading populations, including Hyphomicrobium and Thiobacillus spp., indicated that a higher DMSO oxidation efficiency occurred at a higher Hyphomicrobium spp. abundance in the systems, suggesting that Hyphomicrobium spp. may be more important for complete DMSO oxidation to sulfate compared with Thiobacillus spp. Furthermore, Thiobacillus spp. was more abundant during poor nitrification, while Hyphomicrobium spp. was more abundant during good nitrification. It is suggested that microbial population of DMSO/DMS degrading bacteria is closely linking to both DMSO/DMS degradation efficiency and nitrification performance. PMID:23628318

  5. Isolation and molecular detection of methylotrophic bacteria occurring in the human mouth.

    PubMed

    Anesti, Vasiliki; McDonald, Ian R; Ramaswamy, Meghna; Wade, William G; Kelly, Donovan P; Wood, Ann P

    2005-08-01

    Diverse methylotrophic bacteria were isolated from the tongue, and supra- and subgingival plaque in the mouths of volunteers and patients with periodontitis. One-carbon compounds such as dimethylsulfide in the mouth are likely to be used as growth substrates for these organisms. Methylotrophic strains of Bacillus, Brevibacterium casei, Hyphomicrobium sulfonivorans, Methylobacterium, Micrococcus luteus and Variovorax paradoxus were characterized physiologically and by their 16S rRNA gene sequences. The type strain of B. casei was shown to be methylotrophic. Enzymes of methylotrophic metabolism were characterized in some strains, and activities consistent with growth using known pathways of C1-compound metabolism demonstrated. Genomic DNA from 18 tongue and dental plaque samples from nine volunteers was amplified by the polymerase chain reaction using primers for the 16S rRNA gene of Methylobacterium and the mxaF gene of methanol dehydrogenase. MxaF was detected in all nine volunteers, and Methylobacterium was detected in seven. Methylotrophic activity is thus a feature of the oral bacterial community. PMID:16011760

  6. Methanogenesis in hypersaline ecosystems, and isolation and characterization of eight halophilic, methanogenic bacteria

    SciTech Connect

    Mathrani, I.M.

    1989-01-01

    The present ecological study of methanogenesis in hypersaline ecosystems focused on anaerobic sediment samples collected from several parts of the world. Inocula from solar salterns and natural hypersaline systems were examined for their ability to use catabolic substrates and for conditions which supported methanogenesis. Eight strictly anaerobic, halophilic, methane-producing Archaeobacteria were isolated from enrichment cultures inoculated with samples from hypersaline systems. The physiological and ecological characteristics of the isolates were examined and their phenotypic relatedness to each other and existing species of halophilic methanogens was discussed. The methanogenic, sulfate-reducing, and cellulolytic, halophilic bacteria from sediments of Lake Retba, Senegal were enumerated in depth profiles of sediment core samples. The catabolic substrates and environmental conditions for best growth of each bacterial group were determined. Trimethylamine, dimethylamine, methylamine, methanol, and sometimes dimethylsulfide were used as substrates for growth of methanogenic enrichment cultures and the eight isolates; hydrogen, acetate, or secondary alcohols did not support growth of methanogens. Hydrogen, formate, and lactate supported the growth of halophilic sulfate-reducing bacteria.

  7. Sulfur and primary production in aquatic environments: an ecological perspective.

    PubMed

    Norici, Alessandra; Hell, Ruediger; Giordano, Mario

    2005-12-01

    Sulfur is one of the critical elements in living matter, as it participates in several structural, metabolic and catalytic activities. Photosynthesis is an important process that entails the use of sulfur during both the light and carbon reactions. Nearly half of global photosynthetic carbon fixation is carried out by phytoplankton in the aquatic environment. Aquatic environments are very different from one another with respect to sulfur content: while in the oceans sulfate concentration is constantly high, freshwaters are characterized by daily and seasonal variations and by a wide range of sulfur concentration. The strategies that algal cells adopt for energy and resource allocation often reflect these differences. In the oceans, the amount and chemical form of sulfur has changed substantially during the course of the Earth's history; it is possible that sulfur availability played a role in the evolution of marine phytoplankton communities and it may continue to have appreciable effects on global biogeochemistry and ecology. Phytoplankton is also the main biogenic source of sulfur; sulfur can be released into the atmosphere by algal cells as dimethylsulfide, with possibly important repercussions on global climate. These and related matters are discussed in this review.

  8. Development and testing of a high-resolution model for tropospheric sulfate driven by observation-derived meteorology

    SciTech Connect

    Benkovitz, C.M.

    1994-05-01

    A high-resolution three-dimensional Eulerian transport and transformation model has been developed to simulate concentrations of tropospheric sulfate for specific times and locations; it was applied over the North Atlantic and adjacent continental regions during October and November, 1986. The model represents emissions of anthropogenic SO{sub 2} and sulfate and of biogenic sulfur species, horizontal and vertical transport, gas-phase oxidation of SO{sub 2} and dimethylsulfide, aqueous-phase oxidation of SO{sub 2}, and wet and dry deposition of SO{sub 2}, sulfate, and methanesulfonic acid (MSA). The meteorological driver is the 6-hour output from the forecast model of the European Centre for Medium-Range Weather Forecasts. Calculated sulfate concentrations and column burdens, examined in detail for October 15 and October 22 at 6Z, are related to existing weather patterns. These results exhibit rich temporal and spatial structure; the characteristic (1/e) temporal autocorrelation time for the sulfate column burdens over the central North Atlantic averages 20 hours; 95% of the values were 25 hours or less. The characteristic distance of spatial autocorrelation over this region depends on direction and averages 1,600 km; with 10{sup th} percentile value of 400 km and 90{sup th} percentile value of 1,700 km. Daily average model sulfate concentrations at the lowest vertical accurately represent the spatial variability, temporal episodicity, and absolute magnitudes of surface concentrations measured by monitoring stations in Europe, Canada and Barbados.

  9. Production of Molecular Iodine and Tri-iodide in the Frozen Solution of Iodide: Implication for Polar Atmosphere.

    PubMed

    Kim, Kitae; Yabushita, Akihiro; Okumura, Masanori; Saiz-Lopez, Alfonso; Cuevas, Carlos A; Blaszczak-Boxe, Christopher S; Min, Dae Wi; Yoon, Ho-Il; Choi, Wonyong

    2016-02-01

    The chemistry of reactive halogens in the polar atmosphere plays important roles in ozone and mercury depletion events, oxidizing capacity, and dimethylsulfide oxidation to form cloud-condensation nuclei. Among halogen species, the sources and emission mechanisms of inorganic iodine compounds in the polar boundary layer remain unknown. Here, we demonstrate that the production of tri-iodide (I3(-)) via iodide oxidation, which is negligible in aqueous solution, is significantly accelerated in frozen solution, both in the presence and the absence of solar irradiation. Field experiments carried out in the Antarctic region (King George Island, 62°13'S, 58°47'W) also showed that the generation of tri-iodide via solar photo-oxidation was enhanced when iodide was added to various ice media. The emission of gaseous I2 from the irradiated frozen solution of iodide to the gas phase was detected by using cavity ring-down spectroscopy, which was observed both in the frozen state at 253 K and after thawing the ice at 298 K. The accelerated (photo-)oxidation of iodide and the subsequent formation of tri-iodide and I2 in ice appear to be related with the freeze concentration of iodide and dissolved O2 trapped in the ice crystal grain boundaries. We propose that an accelerated abiotic transformation of iodide to gaseous I2 in ice media provides a previously unrecognized formation pathway of active iodine species in the polar atmosphere.

  10. Use of 13C-Labeled Substrates to Determine Relative Methane Production Rates in Hypersaline Microbial Communities

    NASA Astrophysics Data System (ADS)

    Kelley, C. A.; Bebout, B.; Chanton, J.

    2015-12-01

    Rates and pathways of methane production were determined from photosynthetic soft microbial mats and gypsum-encrusted endoevaporites collected in hypersaline environments from California, Mexico and Chile, as well as an organic-rich mud from a pond in the El Tatio volcanic fields, Chile. Samples (mud, homogenized soft mats and endoevaporites) were incubated anaerobically with deoxygenated site water, and the increase in methane concentration through time in the headspaces of the incubation vials was used to determine methane production rates. To ascertain the substrates used by the methanogens, 13C-labeled methylamines, methanol, dimethylsulfide, acetate or bicarbonate were added to the incubations (one substrate per vial) and the stable isotopic composition of the resulting methane was measured. The vials amended with 13C-labeled methylamines produced the most 13C-enriched methane, generally followed by the 13C-labeled methanol-amended vials. The stable isotope data and the methane production rates were used to determine first order rate constants for each of the substrates at each of the sites. Estimates of individual substrate use revealed that the methylamines produced 55 to 92% of the methane generated, while methanol was responsible for another 8 to 40%.

  11. Interaction between nitrogen and sulfur cycles in the polluted marine boundary layer

    NASA Astrophysics Data System (ADS)

    Yvon, S. A.; Plane, J. M. C.; Nien, C.-F.; Cooper, D. J.; Saltzman, E. S.

    1996-01-01

    Simultaneous measurements are reported of the nitrate radical (NO3), nitrogen dioxide (NO2), ozone (O3), and dimethylsulfide (DMS) in the nighttime marine boundary layer over Biscayne Bay in South Florida. These field observations are analyzed and used to initialize a boundary layer box model which examines the relative importance of the various sinks for NOx in the marine boundary layer. The results show that the observed lifetime of NO3 (≤6 min.) is probably controlled both by the loss of nitrogen pentoxide (N2O5) to reaction with water vapor and aerosols and by the reaction between NO3 and DMS. The model is then extended to investigate the loss of nitrogen oxides from an air parcel that remains in the boundary layer with a constant sea-to-air DMS flux for several days. The principal conclusions are (1) that DMS is a much more important sink for NO3 at lower NO2 levels and (2) that the reaction between NO3 and DMS is an important sink for DMS in the marine boundary layer and could exceed that of the daytime removal by OH.

  12. Distribution and metabolism of dimethylsulfoniopropionate (DMSP) and phylogenetic affiliation of DMSP-assimilating bacteria in northern Baffin Bay/Lancaster Sound

    NASA Astrophysics Data System (ADS)

    Motard-CôTé, J.; Levasseur, M.; Scarratt, M. G.; Michaud, S.; Gratton, Y.; Rivkin, R. B.; Keats, K.; Gosselin, M.; Tremblay, J.-É.; Kiene, R. P.; Lovejoy, C.

    2012-02-01

    We determined the distribution and bacterial metabolism of dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) in the two dominant surface water masses in northern Baffin Bay/Lancaster Sound during September 2008. Concentrations of particulate DMSP (DMSPp; 5-70 nmol L-1) and the DMSPp:Chl a ratios (15-229 nmol μg-1) were relatively high, suggesting the presence of DMSP-rich phytoplankton taxa. Photosynthetic picoeukaryotes and total prokaryotes were tenfold and threefold more abundant in Baffin Bay surface water (BBS) than in Arctic surface water (AS), respectively. Heterotrophic bacterial production (0.07-2.5 μC L-1 d-1) and bacterial turnover rate constants for dissolved DMSP (DMSPd) were low (0.03-0.11 h-1) compared with the values previously reported in warmer and more productive environments. Nonetheless, a relatively large proportion (12%-31%) of the DMSP metabolized by the bacteria was converted into DMS. Additionally, between 40% and 65% of the total bacterial cells incorporated sulfur from DMSPd, with Gammaproteobacteria and non-Roseobacter Alphaproteobacteria (AlfR-) contributing proportionally more to total DMSP-incorporating cells. The contribution of AlfR- to the total prokaryotic community was 50% higher in BBS than in AS, while the bacterial rate constants for DMSPd turnover were 78% higher in BBS than in AS. These results show that the two different Arctic water masses host specific microbial assemblages that result in distinct affinity for DMSP.

  13. Abundant and diverse bacteria involved in DMSP degradation in marine surface waters.

    PubMed

    Howard, Erinn C; Sun, Shulei; Biers, Erin J; Moran, Mary Ann

    2008-09-01

    An expanded analysis of oceanic metagenomic data indicates that the majority of prokaryotic cells in marine surface waters have the genetic capability to demethylate dimethylsulfoniopropionate (DMSP). The 1701 homologues of the DMSP demethylase gene, dmdA, identified in the (2007) Global Ocean Sampling (GOS) metagenome, are sufficient for 58% (+/-9%) of sampled cells to participate in this critical step in the marine sulfur cycle. This remarkable frequency of DMSP-demethylating cells is in accordance with biogeochemical data indicating that marine phytoplankton direct up to 10% of fixed carbon to DMSP synthesis, and that most of this DMSP is subsequently degraded by bacteria via demethylation. The GOS metagenomic data also revealed a new cluster of dmdA sequences (designated Clade E) that implicates marine gammaproteobacteria in DMSP demethylation, along with previously recognized alphaproteobacterial groups Roseobacter and SAR11. Analyses of G+C content and gene order indicate that lateral gene transfer is likely responsible for the wide distribution of dmdA among diverse taxa, contributing to the homogenization of biogeochemical roles among heterotrophic marine bacterioplankton. Candidate genes for the competing bacterial degradation process that converts DMSP to the climate-active gas dimethylsulfide (DMS) (dddD and dddL) occur infrequently in the (2007) GOS metagenome, suggesting either that the key DMS-producing bacterial genes are yet to be identified or that DMS formation by free-living bacterioplankton is insignificant relative to their demethylation activity.

  14. Flavoromics approach in monitoring changes in volatile compounds of virgin rapeseed oil caused by seed roasting.

    PubMed

    Gracka, Anna; Jeleń, Henryk H; Majcher, Małgorzata; Siger, Aleksander; Kaczmarek, Anna

    2016-01-01

    Two varieties of rapeseed (one high oleic - containing 76% of oleic acid, and the other - containing 62% of oleic acid) were used to produce virgin (pressed) oil. The rapeseeds were roasted at different temperature/time combinations (at 140-180°C, and for 5-15min); subsequently, oil was pressed from the roasted seeds. The roasting improved the flavour and contributed to a substantial increase in the amount of a potent antioxidant-canolol. The changes in volatile compounds related to roasting conditions were monitored using comprehensive gas chromatography-mass spectrometry (GC×GC-ToFMS), and the key odorants for the non-roasted and roasted seeds oils were determined by gas chromatography-olfactometry (GC-O). The most important compounds determining the flavour of oils obtained from the roasted seeds were dimethyl sulphide, dimethyltrisulfide, 2,3-diethyl-5-methylpyrazine, 2,3-butenedione, octanal, 3-isopropyl-2-methoxypyrazine and phenylacetaldehyde. For the oils obtained from the non-roasted seeds, the dominant compounds were dimethylsulfide, hexanal and octanal. Based on GC×GC-ToFMS and principal component analysis (PCA) of the data, several compounds were identified that were associated with roasting at the highest temperatures regardless of the rapeseed variety: these were, among others, methyl ketones (2-hexanone, 2-heptanone and 2-octanone). PMID:26592559

  15. Quantification of total and particulate dimethylsulfoniopropionate (DMSP) in five Bermudian coral species across a depth gradient

    NASA Astrophysics Data System (ADS)

    Yost, D. M.; Jones, R.; Rowe, C. L.; Mitchelmore, Carys Louise

    2012-06-01

    The symbiotic dinoflagellate microalgae of corals ( Symbiodinium spp.) contain high concentrations of dimethylsulfoniopropionate (DMSP), a multifunctional metabolite commonly found in many species of marine algae and dinoflagellates. A photoprotective antioxidant function for DMSP and its breakdown products has often been inferred in algae, but its role(s) in the coral-algal symbiosis remains elusive. To examine potential correlations between environmental and physiological parameters and DMSP, total DMSP (DMSPt, from the host coral and zooxanthellae), particulate DMSP (DMSPp, from the zooxanthellae only), coral surface area, and total protein, as well as zooxanthellae density, chlorophyll concentration, cell volume and genotype (i.e., clade) were measured in five coral species from the Diploria- Montastraea- Porites species complex in Bermuda along a depth gradient of 4, 12, 18, and 24 m. DMSPt concentrations were consistently greater than DMSPp concentrations in all species suggesting the possible translocation of DMSP from symbiont to host. D. labyrinthiformis was notably different from the other corals examined, showing DMSPp and DMSPt increases (per coral surface area or tissue biomass) with increasing water depth. However, overall, there were no consistent depth-related patterns in DMSPp and DMSPt concentrations. Further research, investigating dimethylsulfide (DMS), dimethylsulfoxide, and acrylate levels and DMSP-lyase activity in correlation with other biomarker endpoints that have been shown to be depth (i.e., temperature and light) responsive are needed to substantiate the significance of these findings.

  16. Bacterial ethane formation from reduced, ethylated sulfur compounds in anoxic sediments

    USGS Publications Warehouse

    Oremland, R.S.; Whiticar, Michael J.; Strohmaier, F.E.; Kiene, R.P.

    1988-01-01

    Trace levels of ethane were produced biologically in anoxic sediment slurries from five chemically different aquatic environments. Gases from these locations displayed biogenic characteristics, having 12C-enriched values of ??13CH4 (-62 to -86%.), ??13C2H6 (-35 to -55%.) and high ratios (720 to 140,000) of CH4 [C2H6 + C3H8]. Endogenous production of ethane by slurries was inhibited by autoclaving or by addition of the inhibitor of methanogenic bacteria, 2-bromoethanesulfonic acid (BES). Ethane formation was stimulated markedly by ethanethiol (ESH), and, to a lesser extent, by diethylsulfide (DES). Formation of methane and ethane in ESH- or DES-amended slurries was blocked by BES. Experiments showed that ethionine (or an analogous compound) could be a precursor of ESH. Ethylamine or ethanol additions to slurries caused only a minor stimulation of ethane formation. Similarly, propanethiol additions resulted in only a minor enhancement of propane formation. Cell suspensions of a methyltrophic methanogen produced traces of ethane when incubated in the presence of DES, although the organism did not grow on this compound. These results indicate that methanogenic bacteria produce ethane from the traces of ethylated sulfur compounds present in recent sediments. Preliminary estimates of stable carbon isotope fractionation associated with sediment methane formation from dimethylsulfide was about 40%., while ethane formation from DES and ESH was only 4. 6 and 6.5%., respectively. ?? 1988.

  17. DMS gas transfer coefficients from algal blooms in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Bell, T. G.; De Bruyn, W.; Marandino, C. A.; Miller, S. D.; Law, C. S.; Smith, M. J.; Saltzman, E. S.

    2014-11-01

    Air/sea dimethylsulfide (DMS) fluxes and bulk air/sea gradients were measured over the Southern Ocean in February/March 2012 during the Surface Ocean Aerosol Production (SOAP) study. The cruise encountered three distinct phytoplankton bloom regions, consisting of two blooms with moderate DMS levels, and a high biomass, dinoflagellate-dominated bloom with high seawater DMS levels (>15 nM). Gas transfer coefficients were considerably scattered at wind speeds above 5 m s-1. Bin averaging the data resulted in a linear relationship between wind speed and mean gas transfer velocity consistent with that previously observed. However, the wind speed-binned gas transfer data distribution at all wind speeds is positively skewed. The flux and seawater DMS distributions were also positively skewed, which suggests that eddy covariance-derived gas transfer velocities are consistently influenced by additional, log-normal noise. A~flux footprint analysis was conducted during a transect into the prevailing wind and through elevated DMS levels in the dinoflagellate bloom. Accounting for the temporal/spatial separation between flux and seawater concentration significantly reduces the scatter in computed transfer velocity. The SOAP gas transfer velocity data shows no obvious modification of the gas transfer-wind speed relationship by biological activity or waves. This study highlights the challenges associated with eddy covariance gas transfer measurements in biologically active and heterogeneous bloom environments.

  18. Changes in Atmospheric Sulfur Dioxide (SO2) over the English Channel - 1.5 Years of Measurements from the Penlee Point Atmospheric Observatory

    NASA Astrophysics Data System (ADS)

    Yang, Mingxi; Bell, Thomas; Hopkins, Frances; Smyth, Timothy

    2016-04-01

    Atmospheric sulfur dioxide (SO2) was measured continuously from the Penlee Point Atmospheric Observatory near Plymouth, United Kingdom between May 2014 and November 2015. This coastal site is exposed to marine air across a wide wind sector. The predominant southwesterly winds carry relatively clean background Atlantic air. In contrast, air from the southeast is heavily influenced by exhaust plumes from ships in the English Channel as well as near near the Plymouth Sound. International Maritime Organization regulation came into force in January 2015 to reduce sulfur emissions tenfold in Sulfur Emission Control Areas such as the English Channel. We observed a three-fold reduction from 2014 to 2015 in the estimated ship-emitted SO2 during southeasterly winds. Dimethylsulfide (DMS) is an important source of atmospheric SO2 even in this semi-polluted region. The relative contribution of DMS oxidation to the SO2 burden over the English Channel increased from ~1/3 in 2014 to ~1/2 in 2015 due to the reduction in ship sulfur emissions. Our diel analysis suggests that SO2 is removed from the marine atmospheric boundary layer in about half a day, with dry deposition to the ocean accounting for a quarter of the total loss.

  19. The distribution of dimethylsulfoniopropionate in tropical Pacific coral reef invertebrates

    NASA Astrophysics Data System (ADS)

    van Alstyne, Kathryn L.; Schupp, Peter; Slattery, Marc

    2006-08-01

    Dimethylsulfoniopropionate (DMSP) is an important component of the global sulfur cycle and may be involved, via its cleavage product dimethylsulfide, in climate regulation. Although it is common in many algae, reports of DMSP in animals, particularly tropical invertebrates, are limited. This study examined the distribution of DMSP in a diverse group of coral reef invertebrates. DMSP was present in all 22 species of cnidarians and ranged from 9 to 723 μmol g-1 of dry mass (DM) with a mean (± 1SD) of 110 ± 180 μmol g-1 DM. It was not detected in a flatworm and an ascidian or in two of five sponges. Concentrations in sponges ranged from undetectable to 16 μmol g-1 DM with a mean of 4 ± 7 μmol g-1 DM. Within the cnidarians, DMSP concentrations did not differ among orders. Among cnidarian species, DMSP concentrations were correlated with symbiotic zooxanthellae densities. Within cnidarian species, DMSP concentrations of individuals were positively correlated with zooxanthellae densities in three of the four species examined. We speculate that DMSP is dietarily derived in sponges and derived from zooxanthellae in the cnidarians. The functions of DMSP in coral reef invertebrates are not known.

  20. Transcriptomic analysis of a marine bacterial community enriched with dimethylsulfoniopropionate.

    PubMed

    Vila-Costa, Maria; Rinta-Kanto, Johanna M; Sun, Shulei; Sharma, Shalabh; Poretsky, Rachel; Moran, Mary Ann

    2010-11-01

    Dimethylsulfoniopropionate (DMSP) is an important source of reduced sulfur and carbon for marine microbial communities, as well as the precursor of the climate-active gas dimethylsulfide (DMS). In this study, we used metatranscriptomic sequencing to analyze gene expression profiles of a bacterial assemblage from surface waters at the Bermuda Atlantic Time-series Study (BATS) station with and without a short-term enrichment of DMSP (25 nM for 30 min). An average of 303 143 reads were obtained per treatment using 454 pyrosequencing technology, of which 51% were potential protein-encoding sequences. Transcripts from Gammaproteobacteria and Bacteroidetes increased in relative abundance on DMSP addition, yet there was little change in the contribution of two bacterioplankton groups whose cultured members harbor known DMSP degradation genes, Roseobacter and SAR11. The DMSP addition led to an enrichment of transcripts supporting heterotrophic activity, and a depletion of those encoding light-related energy generation. Genes for the degradation of C3 compounds were significantly overrepresented after DMSP addition, likely reflecting the metabolism of the C3 component of DMSP. Mapping these transcripts to known biochemical pathways indicated that both acetyl-CoA and succinyl-CoA may be common entry points of this moiety into the tricarboxylic acid cycle. In a short time frame (30 min) in the extremely oligotrophic Sargasso Sea, different gene expression patterns suggest the use of DMSP by a diversity of marine bacterioplankton as both carbon and sulfur sources.

  1. Quadruple sulfur isotope constraints on the origin and cycling of volatile organic sulfur compounds in a stratified sulfidic lake

    NASA Astrophysics Data System (ADS)

    Oduro, Harry; Kamyshny, Alexey; Zerkle, Aubrey L.; Li, Yue; Farquhar, James

    2013-11-01

    We have quantified the major forms of volatile organic sulfur compounds (VOSCs) distributed in the water column of stratified freshwater Fayetteville Green Lake (FGL), to evaluate the biogeochemical pathways involved in their production. The lake's anoxic deep waters contain high concentrations of sulfate (12-16 mmol L-1) and sulfide (0.12 μmol L-1 to 1.5 mmol L-1) with relatively low VOSC concentrations, ranging from 0.1 nmol L-1 to 2.8 μmol L-1. Sulfur isotope measurements of combined volatile organic sulfur compounds demonstrate that VOSC species are formed primarily from reduced sulfur (H2S/HS-) and zero-valent sulfur (ZVS), with little input from sulfate. Thedata support a role of a combination of biological and abiotic processes in formation of carbon-sulfur bonds between reactive sulfur species and methyl groups of lignin components. These processes are responsible for very fast turnover of VOSC species, maintaining their low levels in FGL. No dimethylsulfoniopropionate (DMSP) was detected by Electrospray Ionization Mass Spectrometry (ESI-MS) in the lake water column or in planktonic extracts. These observations indicate a pathway distinct from oceanic and coastal marine environments, where dimethylsulfide (DMS) and other VOSC species are principally produced via the breakdown of DMSP by plankton species.

  2. Surface Ocean—Lower Atmosphere Processes

    NASA Astrophysics Data System (ADS)

    Le Quéré, Corinne; Saltzman, Eric S.

    The focus of Surface Ocean-Lower Atmosphere Processes is biogeochemical interactions between the surface ocean and the lower atmosphere. This volume is an outgrowth of the Surface Ocean-Lower Atmosphere Study (SOLAS) Summer School. The volume is designed to provide graduate students, postdoctoral fellows, and researchers from a wide range of academic backgrounds with a basis for understanding the nature of ocean-atmosphere interactions and the current research issues in this area. The volume highlights include the following: • Background material on ocean and atmosphere structure, circulation, and chemistry and on marine ecosystems • Integrative chapters on the global carbon cycle and ocean biogeochemistry • Issue-oriented chapters on the iron cycle and dimethylsulfide • Tool-oriented chapters on biogeochemical modeling and remote sensing • A framework of underlying physical/chemical/biological principles, as well as perspectives on current research issues in the field. The readership for this book will include graduate students and/or advanced undergraduate students, postdoctoral researchers, and researchers in the fields of oceanography and atmospheric science. It will also be useful for experienced researchers in specific other disciplines who wish to broaden their perspectives on the complex biogeochemical coupling between ocean and atmosphere and the importance of this coupling to understanding global change.

  3. Analysis of volatile compounds of Iberian dry-cured loins with different intramuscular fat contents using SPME-DED.

    PubMed

    Ventanas, Sonia; Estevez, Mario; Andrés, Ana I; Ruiz, Jorge

    2008-05-01

    In order to study the effect of both, ripening time and IMF content on the volatile profile of Iberian dry-cured loin, volatile compounds from the headspace of 10 Iberian dry-cured loins with different intramuscular fat contents (IMF), low (average IMF content of 2.3%) and high (average IMF content of 6.7%), at days 40 and 55 of the ripening process were analysed using SPME coupled to a direct extraction device (DED) and subsequent gas chromatography/mass spectrometry (GC/MS). Chromatographic areas of the main chemical families detected (hydrocarbons, aldehydes, alcohols, ketones and acids) increased with ripening time. A higher total chromatographic area was detected in the headspace of high IMF loins compared to low IMF ones. Several volatile compounds derived from lipid oxidative reactions, such as hexanol, octanal, (E,E)-2,4-heptadienal or (E)-2-decenal, and others from the degradation of certain amino acids, such as dimethylsulfide, 3-methylbutanal or phenylacetaldehyde, showed higher chromatographic areas in the headspace of high IMF loins than in low IMF ones. Thus, IMF content could influence both the generation of volatile compounds and the transfer of such compounds from the product matrix to the headspace.

  4. Microaerobic steroid biosynthesis and the molecular fossil record of Archean life.

    PubMed

    Waldbauer, Jacob R; Newman, Dianne K; Summons, Roger E

    2011-08-16

    The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth's evolution. Among the various geochemical proxies for the presence of O(2) in the environment, molecular fossils offer a unique record of O(2) where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires molecular oxygen, fossil steranes have been used to draw inferences about aerobiosis in the early Precambrian. However, better quantitative constraints on the O(2) requirement of this biochemistry would clarify the implications of these molecular fossils for environmental conditions at the time of their production. Here we demonstrate that steroid biosynthesis is a microaerobic process, enabled by dissolved O(2) concentrations in the nanomolar range. We present evidence that microaerobic marine environments (where steroid biosynthesis was possible) could have been widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O(2). In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today. PMID:21825157

  5. Climate interaction mechanism between solar activity and terrestrial biota

    NASA Astrophysics Data System (ADS)

    Osorio-Rosales, J.; Mendoza, B.

    2012-07-01

    The solar activity has been proposed as one of the main factors of Earth's climate variability, however biological processes have been also proposed. Dimethylsulfide (DMS) is the main biogenic sulfur compound in the atmosphere. DMS 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 influences them through regulations of the chemical composition of the atmosphere. In the present study we used different methods of analysis to investigate the relationship between the DMS, Low Clouds, Ultraviolet Radiation A (UVA) and Sea Surface Temperature (SST) in the Southern Hemisphere. We found that the series analyzed have different periodicities which can be associated with climatic and solar phenomena such as El Niño, the Quasi-Biennial Oscillation (QBO) and the changes in solar activity. Also, we found an anticorrelation between DMS and UVA, the relation between DMS and clouds is mainly non-linear and there is a correlation between DMS and SST. Then, our results suggest a positive feedback interaction among DMS, solar radiation and cloud at time-scales shorter than the solar cycle.

  6. Production and loss of methanesulfonate and non-sea salt sulfate in the equatorial Pacific marine boundary layer

    SciTech Connect

    Huebert, B.J.; Wylie, D.J.; Zhuang, L.; Heath, J.A.

    1996-04-01

    The authors measured the concentrations of aerosol methanesulfonate (MSA) and non-sea salt sulfate (NSS) in the remote pacific marine boundary layer (MBL) at Christmas Island (157{degrees}W, 2{degrees}N) in July and August of 1994. The project-average MSA displayed a distinct diurnal variation, decreasing to 8.6 ppt at sunrise and increasing to 12.1 ppt by sunset. The average NSS diurnal variation ranged from 196 ppt at sunrise to 235 ppt at sunset. Large-particle dry deposition may account for 10-20% of the observed nighttime decrease, with entrainment of cleaner free tropospheric air responsible for the rest. The entrainment velocity inferred from the nighttime decrease averaged 0.5 {+-} 0.2 cm/s. A simple model suggests that NSS and MSA were produced at rates of about 74 and 6 ppt per day, respectively. Between 30 and 40% of the daily dimethylsulfide (DMS) flux forms NSS and 3% forms MSA. 11 refs., 3 fig.

  7. Aerosol dynamics in the equatorial Pacific Marine boundary layer: Microphysics, diurnal cycles and entertainment

    SciTech Connect

    Clarke, A D; Litchy, M; Li, Z

    1996-04-01

    During July-August of 1994 the authors measured the size resolved physiochemical properties of aerosol particles at Christmas Island in the equatorial Pacific. In spite of rapid diurnal conversion of dimethylsulfide (DMS) to sulfur dioxide (SO{sub 2}) the authors found no evidence for new particle production in the marine boundary layer (MBL) and more than 95% of all particles were consistently larger than 0.02{mu}m diameter, indicating an aged aerosol number (size-distribution) was bimodal with peaks near 0.05{mu}m and 0.2{mu}m particle diameter (D{sub p}) and had a cloud-processed intermode minimum at about 0.09{mu}m that varied in phase with diurnal changes in ozone concentration. This suggests that the number distribution for condensation nuclei (CN) and cloud condensation (CCN) was maintained by a quasiequilibrium between entrainment (estimated to be 0.6{+-}0.2 cm s{sup {minus}1}) from sources aloft and processes in the MBL. This implies a replenishment timescale for nuclei of about 2 and 4 days for this region. The stability of the distribution and the 0.09{mu}m cloud processed minima suggests trade winds cumulus supersaturations near 0.35% and updrafts near 1 m s{sup {minus}1}. 17 refs., 4 fig., 1 tab.

  8. Formation of methane and carbon dioxide from dimethylselenide in anoxic sediments and by a methanogenic bacterium

    USGS Publications Warehouse

    Oremland, Ronald S.; Zehr, Jon P.

    1986-01-01

    Anaerobic San Francisco Bay salt marsh sediments rapidly metabolized [14C]dimethylselenide (DMSe) to 14CH4 and 14CO2. Addition of selective inhibitors (2-bromoethanesulfonic acid or molybdate) to these sediments indicated that both methanogenic and sulfate-respiring bacteria could degrade DMSe to gaseous products. However, sediments taken from the selenium-contaminated Kesterson Wildlife Refuge produced only 14CO2 from [14C]DMSe, implying that methanogens were not important in the Kesterson samples. A pure culture of a dimethylsulfide (DMS)-grown methylotrophic methanogen converted [14C]DMSe to 14CH4 and14CO2. However, the organism could not grow on DMSe. Addition of DMS to either sediments or the pure culture retarded the metabolism of DMSe. This effect appeared to be caused by competitive inhibition, thereby indicating a common enzyme system for DMS and DMSe metabolism. DMSe appears to be degraded as part of the DMS pool present in anoxic environments. These results suggest that methylotrophic methanogens may demethylate methylated forms of other metals and metalloids found in nature.

  9. The genetic potential for key biogeochemical processes in Arctic frost flowers and young sea ice revealed by metagenomic analysis.

    PubMed

    Bowman, Jeff S; Berthiaume, Chris T; Armbrust, E Virginia; Deming, Jody W

    2014-08-01

    Newly formed sea ice is a vast and biogeochemically active environment. Recently, we reported an unusual microbial community dominated by members of the Rhizobiales in frost flowers at the surface of Arctic young sea ice based on the presence of 16S gene sequences related to these strains. Here, we use metagenomic analysis of two samples, from a field of frost flowers and the underlying young sea ice, to explore the metabolic potential of this surface ice community. The analysis links genes for key biogeochemical processes to the Rhizobiales, including dimethylsulfide uptake, betaine glycine turnover, and halocarbon production. Nodulation and nitrogen fixation genes characteristic of terrestrial root-nodulating Rhizobiales were generally lacking from these metagenomes. Non-Rhizobiales clades at the ice surface had genes that would enable additional biogeochemical processes, including mercury reduction and dimethylsulfoniopropionate catabolism. Although the ultimate source of the observed microbial community is not known, considerations of the possible role of eolian deposition or transport with particles entrained during ice formation favor a suspended particle source for this microbial community.

  10. Diversity of bacterial dimethylsulfoniopropionate degradation genes in surface seawater of Arctic Kongsfjorden

    NASA Astrophysics Data System (ADS)

    Zeng, Yin-Xin; Qiao, Zong-Yun; Yu, Yong; Li, Hui-Rong; Luo, Wei

    2016-09-01

    Dimethylsulfoniopropionate (DMSP), which is the major source of organic sulfur in the world’s oceans, plays a significant role in the global sulfur cycle. This compound is rapidly degraded by marine bacteria either by cleavage to dimethylsulfide (DMS) or demethylation to 3-methylmercaptopropionate (MMPA). The diversity of genes encoding bacterial demethylation (dmdA) and DMS production (dddL and dddP) were measured in Arctic Kongsfjorden. Both dmdA and dddL genes were detected in all stations along a transect from the outer to the inner fjord, while dddP gene was only found in the outer and middle parts of the fjord. The dmdA gene was completely confined to the Roseobacter clade, while the dddL gene was confined to the genus Sulfitobacter. Although the dddP gene pool was also dominated by homologs from the Roseobacter clade, there were a few dddP genes showing close relationships to both Alphaproteobacter and Gammaproteobacter. The results of this study suggest that the Roseobacter clade may play an important role in DMSP catabolism via both demethylation and cleavage pathways in surface waters of Kongsfjorden during summer.

  11. Vertically fired fume incinerator reduces VOC, HCl emissions while adapting to limited space

    SciTech Connect

    Olson, D.A.; Wickersham, C.P.

    1985-03-01

    Merck's Flint River plant in Albany, GA had been concerned with the control of dimethylsulfide (DMS) and methyl chloride. In November 1980, the state of Georgia enacted air pollution regulations requiring a 90% (by weight) reduction of all volatile organic compound (VOC) emission. A complete vertical incineration system was selected that could easily be installed in the available area. Total space for the vertically fired incineration system is 510 sq ft, which is 64% less than for a comparable horizontally configured system. The 39 hp system has a heat input of 5.6MM Btu/hr. Since completion in March 1984, the incinerator system has proven to be reliable with good corrosion resistance. High control efficiency (99.99 + %) has given Merck an ultimate disposal method for converting VOCs to inert byproducts. Stack emissions (on a dry volume basis) are approximately: 150 ppm (maximum) NO/sub x/ as NO/sub 2/, less than 5 ppm HCl, less than 5 ppm chlorine, and 25 ppm (maximum) SO/sub 2/. Confirmation of these emissions levels is anticipated once the engineering staff can perform the necessary testing procedures.

  12. An analytical system enabling consistent and long-term measurement of atmospheric dimethyl sulfide

    NASA Astrophysics Data System (ADS)

    Jang, Sehyun; Park, Ki-Tae; Lee, Kitack; Suh, Young-Sang

    2016-06-01

    We describe here an analytical system capable of continuous measurement of atmospheric dimethylsulfide (DMS) at pptv levels. The system uses customized devices for detector calibration and for DMS trapping and desorption that are controlled using a data acquisition system (based on Visual Basic 6.0/C 6.0) designed to maximize the efficiency of DMS analysis in a highly sensitive pulsed flame photometric detector housed in a gas chromatograph. The fully integrated system, which can sample approximately 6 L of air during a 1-hr sampling, was used to measure the atmospheric DMS mixing ratio over the Atlantic sector of the Arctic Ocean over 3 full annual growth cycles of phytoplankton in 2010, 2014, and 2015, with minimal routine maintenance and interruptions. During the field campaigns, the measured atmospheric DMS mixing ratio varied over a considerable range, from <1.5 pptv to maximum levels of 298 pptv in 2010, 82 pptv in 2014, and 429 pptv in 2015. The operational period covering the 3 full annual growth cycles of phytoplankton showed that the system is suitable for uninterrupted measurement of atmospheric DMS mixing ratios in extreme environments. Moreover, the findings obtained using the system showed it to be useful in identifying ocean DMS source regions and changes in source strength.

  13. Pathways and substrate specificity of DMSP catabolism in marine bacteria of the Roseobacter clade.

    PubMed

    Dickschat, Jeroen S; Zell, Claudia; Brock, Nelson L

    2010-02-15

    The volatiles released by Phaeobacter gallaeciensis, Oceanibulbus indolifex and Dinoroseobacter shibae have been investigated by GC-MS, and several MeSH-derived sulfur volatiles have been identified. An important sulfur source in the oceans is the algal metabolite dimethylsulfoniopropionate (DMSP). Labelled [2H6]DMSP was fed to the bacteria to investigate the production of volatiles from this compound through the lysis pathway to [2H6]dimethylsulfide or the demethylation pathway to [2H3]-3-(methylmercapto)propionic acid and lysis to [2H3]MeSH. [2H6]DMSP was efficiently converted to [2H3]MeSH by all three species. Several DMSP derivatives were synthesised and used in feeding experiments. Strong dealkylation activity was observed for the methylated ethyl methyl sulfoniopropionate and dimethylseleniopropionate, as indicated by the formation of EtSH- and MeSeH-derived volatiles, whereas no volatiles were formed from dimethyltelluriopropionate. In contrast, the dealkylation activity for diethylsulfoniopropionate was strongly reduced, resulting in only small amounts of EtSH-derived volatiles accompanied by diethyl sulfide in P. gallaeciensis and O. indolifex, while D. shibae produced the related oxidation product diethyl sulfone. The formation of diethyl sulfide and diethyl sulfone requires the lysis pathway, which is not active for [2H6]DMSP. These observations can be explained by a shifted distribution between the two competing pathways due to a blocked dealkylation of ethylated substrates.

  14. Sensitivity of modelled sulfate aerosol and its radiative effect on climate to ocean DMS concentration and air-sea flux

    NASA Astrophysics Data System (ADS)

    Tesdal, Jan-Erik; Christian, James R.; Monahan, Adam H.; von Salzen, Knut

    2016-09-01

    Dimethylsulfide (DMS) is a well-known marine trace gas that is emitted from the ocean and subsequently oxidizes to sulfate in the atmosphere. Sulfate aerosols in the atmosphere have direct and indirect effects on the amount of solar radiation reaching the Earth's surface. Thus, as a potential source of sulfate, ocean efflux of DMS needs to be accounted for in climate studies. Seawater concentration of DMS is highly variable in space and time, which in turn leads to high spatial and temporal variability in ocean DMS emissions. Because of sparse sampling (in both space and time), large uncertainties remain regarding ocean DMS concentration. In this study, we use an atmospheric general circulation model with explicit aerosol chemistry (CanAM4.1) and several climatologies of surface ocean DMS concentration to assess uncertainties about the climate impact of ocean DMS efflux. Despite substantial variation in the spatial pattern and seasonal evolution of simulated DMS fluxes, the global-mean radiative effect of sulfate is approximately linearly proportional to the global-mean surface flux of DMS; the spatial and temporal distribution of ocean DMS efflux has only a minor effect on the global radiation budget. The effect of the spatial structure, however, generates statistically significant changes in the global-mean concentrations of some aerosol species. The effect of seasonality on the net radiative effect is larger than that of spatial distribution and is significant at global scale.

  15. Influence of Nitrate Radical on the Oxidation of Dimethyl Sulfide in a Polluted Marine Environment: Implications for non Sea-Salt Sulfate Production

    NASA Astrophysics Data System (ADS)

    Stark, H.; Brown, S. S.; Goldan, P. D.; Aldener, M.; Kuster, W. C.; Jakoubek, R.; Fehsenfeld, F. C.; Meagher, J. F.; Bates, T. S.; Ravishankara, A. R.

    2006-12-01

    Dimethylsulfide (DMS, CH3SCH3) is the largest natural source of non-sea-salt sulfate (nss) in the marine environment via its oxidation to sulfuric acid (H2SO4). Aerosol particles produced from marine sulfur emissions may have a significant influence on the Earth's climate. The most important oxidants for DMS are hydroxyl (OH) radicals during daytime and nitrate (NO3) radicals during nighttime. Nitrate radical is an important nocturnal oxidant for several other biogenic and some anthropogenic compounds mainly originating from land. We performed simultaneous, in-situ atmospheric measurements of dimethyl sulfide (DMS) and nitrate radical (NO3) from the NOAA research vessel Ronald H. Brown off the New England Coast during the summer of 2002. We observed a clear anticorrelation between NO3 and DMS on 13 of 17 measurement nights. Diurnal averages indicate a stronger oxidation by NO3 at night than by OH at daytime under polluted conditions. These increased oxidation rates may influence global new nss aerosol particle production, depending on the chemical oxidation mechanism of DMS and the yield of sulfuric acid. We will discuss the influence of different scenarios for nss production from DMS oxidation mechanisms. We will also discuss the possible influence of halogens (e.g. Cl and BrO) on the DMS oxidation and their implication on nss aerosol production. Our measurements suggest that anthropogenic NO2 sources may influence marine boundary layer chemistry for up to 5 days or 3000 km downwind from NOx source regions.

  16. Diversity of bacterial dimethylsulfoniopropionate degradation genes in surface seawater of Arctic Kongsfjorden

    PubMed Central

    Zeng, Yin-Xin; Qiao, Zong-Yun; Yu, Yong; Li, Hui-Rong; Luo, Wei

    2016-01-01

    Dimethylsulfoniopropionate (DMSP), which is the major source of organic sulfur in the world’s oceans, plays a significant role in the global sulfur cycle. This compound is rapidly degraded by marine bacteria either by cleavage to dimethylsulfide (DMS) or demethylation to 3-methylmercaptopropionate (MMPA). The diversity of genes encoding bacterial demethylation (dmdA) and DMS production (dddL and dddP) were measured in Arctic Kongsfjorden. Both dmdA and dddL genes were detected in all stations along a transect from the outer to the inner fjord, while dddP gene was only found in the outer and middle parts of the fjord. The dmdA gene was completely confined to the Roseobacter clade, while the dddL gene was confined to the genus Sulfitobacter. Although the dddP gene pool was also dominated by homologs from the Roseobacter clade, there were a few dddP genes showing close relationships to both Alphaproteobacter and Gammaproteobacter. The results of this study suggest that the Roseobacter clade may play an important role in DMSP catabolism via both demethylation and cleavage pathways in surface waters of Kongsfjorden during summer. PMID:27604458

  17. Microaerobic steroid biosynthesis and the molecular fossil record of Archean life

    PubMed Central

    Waldbauer, Jacob R.; Newman, Dianne K.; Summons, Roger E.

    2011-01-01

    The power of molecular oxygen to drive many crucial biogeochemical processes, from cellular respiration to rock weathering, makes reconstructing the history of its production and accumulation a first-order question for understanding Earth’s evolution. Among the various geochemical proxies for the presence of O2 in the environment, molecular fossils offer a unique record of O2 where it was first produced and consumed by biology: in sunlit aquatic habitats. As steroid biosynthesis requires molecular oxygen, fossil steranes have been used to draw inferences about aerobiosis in the early Precambrian. However, better quantitative constraints on the O2 requirement of this biochemistry would clarify the implications of these molecular fossils for environmental conditions at the time of their production. Here we demonstrate that steroid biosynthesis is a microaerobic process, enabled by dissolved O2 concentrations in the nanomolar range. We present evidence that microaerobic marine environments (where steroid biosynthesis was possible) could have been widespread and persistent for long periods of time prior to the earliest geologic and isotopic evidence for atmospheric O2. In the late Archean, molecular oxygen likely cycled as a biogenic trace gas, much as compounds such as dimethylsulfide do today. PMID:21825157

  18. Role of sea ice and hemispheric circulation mode on sulphur oxidised compounds (Methanesulfonate and Sulfate) in the Artic aerosol

    NASA Astrophysics Data System (ADS)

    Becagli, Silvia; Calzolai, Giulia; Dayan, Uri; Di Biagio, Claudia; di Sarra, Alcide; Frosini, Daniele; Mazzola, Mauro; Rugi, Francesco; Severi, Mirko; Traversi, Rita; Vitale, Vito; Udisti, Roberto

    2013-04-01

    The recent decline in sea ice cover in the Arctic Ocean is expected to affect the regional radiation budget and to influence the ocean-atmosphere exchange of dimethylsulfide (DMS), thus the amount of biogenic aerosols formed from its atmospheric oxidation, such as methanesulfonate (MS-) and non-sea salt sulphate (nssSO42-). This study examines the temporal evolution of atmospheric MS- and nssSO42-, as measured in atmospheric aerosols, at Ny-Ålesund, (78.9°N, 11.9°E, Svalbard islands) and Thule (76.5°N, 68.8°W, Greenland) during three years (2010-12). Aerosol sampling was carried out using a PM10 sampler with Teflon filters, and a 12-stage impactor (SDI, Small Deposit-area Impactor) with polycarbonate filters. Analyses were performed by ion chromatography, for ion composition, and ICP-SFMS, for selected metals; both techniques are sufficiently sensitive, accurate, and reproducible to be applied to very low atmospheric load of aerosol particles, typical of remote polar regions. The evolution of MS- and nssSO4 concentrations was analysed as a function of speciation (as acidic species or ammonium salt), size distribution, and airmass pathways. This study reveals that nssSO4 is meanly associated with long range transport from anthropic sources, and presents a relative maximum in spring. Conversely, MS- arises from natural local sources and shows a peak in mid-summer. A large interannual variability is observed in MS- concentration with values in spring-summer 2010 in both the stations higher than in the other summers. In the previous winter a larger sea ice extent and larger sea ice melting surface in the following spring were observed. Arrigo et al. (2008) have observed a 22% increase in the annual primary productivity, that has been attributed to a longer phytoplankton growing season connected with the progressive decline in sea ice coverage in the Arctic over the past decade. Modeling results (Gabric et al., 2005) suggest that an increase in DMS production would

  19. Structures of dimethylsulfoniopropionate-dependent demethylase from the marine organism Pelagabacter ubique

    SciTech Connect

    Schuller, David J.; Reisch, Chris R.; Moran, Mary Ann; Whitman, William B.; Lanzilotta, William N.

    2012-01-20

    Dimethylsulfoniopropionate (DMSP) is a ubiquitous algal metabolite and common carbon and sulfur source for marine bacteria. DMSP is a precursor for the climatically active gas dimethylsulfide that is readily oxidized to sulfate, sulfur dioxide, methanesulfonic acid, and other products that act as cloud condensation nuclei. Although the environmental importance of DMSP metabolism has been known for some time, the enzyme responsible for DMSP demethylation by marine bacterioplankton, dimethylsufoniopropionate-dependent demethylase A (DmdA, EC 2.1.1.B5), has only recently been identified and biochemically characterized. In this work, we report the structure for the apoenzyme DmdA from Pelagibacter ubique (2.1 {angstrom}), as well as for DmdA co-crystals soaked with substrate DMSP (1.6 {angstrom}) or the cofactor tetrahydrofolate (THF) (1.6 {angstrom}). Surprisingly, the overall fold of the DmdA is not similar to other enzymes that typically utilize the reduced form of THF and in fact is a triple domain structure similar to what has been observed for the glycine cleavage T protein or sarcosine oxidase. Specifically, while the THF binding fold appears conserved, previous biochemical studies have shown that all enzymes with a similar fold produce 5,10-methylene-THF, while DmdA catalyzes a redox-neutral methyl transfer reaction to produce 5-methyl-THF. On the basis of the findings presented herein and the available biochemical data, we outline a mechanism for a redox-neutral methyl transfer reaction that is novel to this conserved THF binding domain.

  20. Modeling natural emissions in the Community Multiscale Air Quality (CMAQ) Model-I: building an emissions data base

    NASA Astrophysics Data System (ADS)

    Smith, S. N.; Mueller, S. F.

    2010-05-01

    A natural emissions inventory for the continental United States and surrounding territories is needed in order to use the US Environmental Protection Agency Community Multiscale Air Quality (CMAQ) Model for simulating natural air quality. The CMAQ air modeling system (including the Sparse Matrix Operator Kernel Emissions (SMOKE) emissions processing system) currently estimates non-methane volatile organic compound (NMVOC) emissions from biogenic sources, nitrogen oxide (NOx) emissions from soils, ammonia from animals, several types of particulate and reactive gas emissions from fires, as well as sea salt emissions. However, there are several emission categories that are not commonly treated by the standard CMAQ Model system. Most notable among these are nitrogen oxide emissions from lightning, reduced sulfur emissions from oceans, geothermal features and other continental sources, windblown dust particulate, and reactive chlorine gas emissions linked with sea salt chloride. A review of past emissions modeling work and existing global emissions data bases provides information and data necessary for preparing a more complete natural emissions data base for CMAQ applications. A model-ready natural emissions data base is developed to complement the anthropogenic emissions inventory used by the VISTAS Regional Planning Organization in its work analyzing regional haze based on the year 2002. This new data base covers a modeling domain that includes the continental United States plus large portions of Canada, Mexico and surrounding oceans. Comparing July 2002 source data reveals that natural emissions account for 16% of total gaseous sulfur (sulfur dioxide, dimethylsulfide and hydrogen sulfide), 44% of total NOx, 80% of reactive carbonaceous gases (NMVOCs and carbon monoxide), 28% of ammonia, 96% of total chlorine (hydrochloric acid, nitryl chloride and sea salt chloride), and 84% of fine particles (i.e., those smaller than 2.5 μm in size) released into the atmosphere

  1. Modeling natural emissions in the Community Multiscale Air Quality (CMAQ) model - Part 1: Building an emissions data base

    NASA Astrophysics Data System (ADS)

    Smith, S. N.; Mueller, S. F.

    2010-01-01

    A natural emissions inventory for the continental United States and surrounding territories is needed in order to use the US Environmental Protection Agency Community Multiscale Air Quality (CMAQ) Model for simulating natural air quality. The CMAQ air modeling system (including the Sparse Matrix Operator Kernel Emissions (SMOKE) emissions processing system) currently estimates volatile organic compound (VOC) emissions from biogenic sources, nitrogen oxide (NOx) emissions from soils, ammonia from animals, several types of particulate and reactive gas emissions from fires, as well as windblown dust and sea salt emissions. However, there are several emission categories that are not commonly treated by the standard CMAQ Model system. Most notable among these are nitrogen oxide emissions from lightning, reduced sulfur emissions from oceans, geothermal features and other continental sources, and reactive chlorine gas emissions linked with sea salt chloride. A review of past emissions modeling work and existing global emissions data bases provides information and data necessary for preparing a more complete natural emissions data base for CMAQ applications. A model-ready natural emissions data base is developed to complement the anthropogenic emissions inventory used by the VISTAS Regional Planning Organization in its work analyzing regional haze based on the year 2002. This new data base covers a modeling domain that includes the continental United States plus large portions of Canada, Mexico and surrounding oceans. Comparing July 2002 source data reveals that natural emissions account for 16% of total gaseous sulfur (sulfur dioxide, dimethylsulfide and hydrogen sulfide), 44% of total NOx, 80% of reactive carbonaceous gases (VOCs and carbon monoxide), 28% of ammonia, 96% of total chlorine (hydrochloric acid, nitryl chloride and sea salt chloride), and 84% of fine particles (i.e., those smaller than 2.5 μm in size) released into the atmosphere. The seasonality and

  2. Investigating the 'Iron Hypothesis' in the North Pacific: Trans-Pacific Dust and Methanesulfonate (MSA) in the Denali Ice Core, Alaska

    NASA Astrophysics Data System (ADS)

    Saylor, P. L.; Osterberg, E. C.; Winski, D.; Ferris, D. G.; Koffman, B. G.; Kreutz, K. J.; Wake, C. P.; Campbell, S. W.

    2015-12-01

    Oceanic deposition of Asian-sourced, Iron-rich dust particulate has been linked to enhanced phytoplankton productivity in regions of the Pacific Ocean. High Nutrient Low Chlorophyll (HNLC) ocean regions, such as the North Pacific, are hypothesized to play a significant role in changing atmospheric CO­2 concentrations on glacial-interglacial timescales. Phytoplankton blooms generate methanesulfonate (MSA), an atmospheric oxidation product of dimethylsulfide (DMS) that is readily aerosolized and deposited in nearby glacial ice. In the summer of 2013, an NSF-funded team from Dartmouth College and the Universities of Maine and New Hampshire collected two 1000 year-long parallel ice cores to bedrock from the summit plateau of Mount Hunter in Denali National Park, Alaska (62.940° N, 151.088° W, 3912 m elevation). The Mt. Hunter ice core site is well situated to record changes in trans-Pacific dust flux and MSA emissions in the North Pacific. Here we investigate the history of dust flux to Denali over the last millennium using major and trace element chemistry and microparticle concentration and size distribution data from the Mt. Hunter cores. We evaluate potential controlling mechanisms on Denali dust flux including conditions at Asian dust sources (storminess, wind speed, precipitation), the strength of the Aleutian Low, and large-scale climate modes such as the El Niño-Southern Oscillation and the Pacific Decadal Oscillation. We also evaluate the Mt. Hunter record for relationships between dust flux and MSA concentrations to investigate whether dust fertilization enhanced North Pacific phytoplankton production over the past 1000 years. Future work will create a composite North Pacific dust record using new and existing Mt. Logan ice core records to evaluate these relationships over the entire Holocene.

  3. Emission of volatile sulfur compounds from spruce trees

    SciTech Connect

    Rennenberg, H.; Huber, B.; Schroeder, P.; Stahl, K.; Haunold, W.; Georgil, H.W.; Slovik, S.; Pfanz, H. )

    1990-03-01

    Spruce (Picea abies L.) trees from the same clone were supplied with different, but low, amounts of plant available sulfate in the soil (9.7-18.1 milligrams per 100 grams of soil). Branches attached to the trees were enclosed in a dynamic gas exchange cuvette and analyzed for the emission of volatile sulfur compounds. Independent of the sulfate supply in the soil, H{sub 2}S was the predominant reduced sulfur compound continuously emitted from the branches with high rates during the day and low rates in the night. In the light, as well as in the dark, the rates of H{sub 2}S emission increased exponentially with increasing water vapor flux from the needles. Approximately 1 nanomole of H{sub 2}S was found to be emitted per mole of water. When stomata were closed completely, only minute emission of H{sub 2}S was observed. Apparently, H{sub 2}S emission from the needles is highly dependent on stromatal aperture, and permeation through the cuticle is negligible. In several experiments, small amounts of dimethylsulfide and carbonylsulfide were also detected in a portion of the samples. However, SO{sub 2} was the only sulfur compound consistently emitted from branches of spruce trees in addition to H{sub 2}S. Emission of SO{sub 2} mainly proceeded via an outburst starting before the beginning of the light period. The total amount of SO{sub 2} emitted from the needles during this outburst was correlated with the plant available sulfate in the soil. The diurnal changes in sulfur metabolism that may result in an outburst of SO{sub 2} are discussed.

  4. Influence of Sea Ice on Arctic Marine Sulfur Biogeochemistry in the Community Climate System Model

    SciTech Connect

    Deal, Clara; Jin, Meibing

    2013-06-30

    Global climate models (GCMs) have not effectively considered how responses of arctic marine ecosystems to a warming climate will influence the global climate system. A key response of arctic marine ecosystems that may substantially influence energy exchange in the Arctic is a change in dimethylsulfide (DMS) emissions, because DMS emissions influence cloud albedo. This response is closely tied to sea ice through its impacts on marine ecosystem carbon and sulfur cycling, and the ice-albedo feedback implicated in accelerated arctic warming. To reduce the uncertainty in predictions from coupled climate simulations, important model components of the climate system, such as feedbacks between arctic marine biogeochemistry and climate, need to be reasonably and realistically modeled. This research first involved model development to improve the representation of marine sulfur biogeochemistry simulations to understand/diagnose the control of sea-ice-related processes on the variability of DMS dynamics. This study will help build GCM predictions that quantify the relative current and possible future influences of arctic marine ecosystems on the global climate system. Our overall research objective was to improve arctic marine biogeochemistry in the Community Climate System Model (CCSM, now CESM). Working closely with the Climate Ocean Sea Ice Model (COSIM) team at Los Alamos National Laboratory (LANL), we added 1 sea-ice algae and arctic DMS production and related biogeochemistry to the global Parallel Ocean Program model (POP) coupled to the LANL sea ice model (CICE). Both CICE and POP are core components of CESM. Our specific research objectives were: 1) Develop a state-of-the-art ice-ocean DMS model for application in climate models, using observations to constrain the most crucial parameters; 2) Improve the global marine sulfur model used in CESM by including DMS biogeochemistry in the Arctic; and 3) Assess how sea ice influences DMS dynamics in the arctic marine

  5. Aboveground and Belowground Herbivores Synergistically Induce Volatile Organic Sulfur Compound Emissions from Shoots but Not from Roots.

    PubMed

    Danner, Holger; Brown, Phil; Cator, Eric A; Harren, Frans J M; van Dam, Nicole M; Cristescu, Simona M

    2015-07-01

    Studies on aboveground (AG) plant organs have shown that volatile organic compound (VOC) emissions differ between simultaneous attack by herbivores and single herbivore attack. There is growing evidence that interactive effects of simultaneous herbivory also occur across the root-shoot interface. In our study, Brassica rapa roots were infested with root fly larvae (Delia radicum) and the shoots infested with Pieris brassicae, either singly or simultaneously, to study these root-shoot interactions. As an analytical platform, we used Proton Transfer Reaction Mass Spectrometry (PTR-MS) to investigate VOCs over a 3 day time period. Our set-up allowed us to monitor root and shoot emissions concurrently on the same plant. Focus was placed on the sulfur-containing compounds; methanethiol, dimethylsulfide (DMS), and dimethyldisulfide (DMDS), because these compounds previously have been shown to be biologically active in the interactions of Brassica plants, herbivores, parasitoids, and predators, yet have received relatively little attention. The shoots of plants simultaneously infested with AG and belowground (BG) herbivores emitted higher levels of sulfur-containing compounds than plants with a single herbivore species present. In contrast, the emission of sulfur VOCs from the plant roots increased as a consequence of root herbivory, independent of the presence of an AG herbivore. The onset of root emissions was more rapid after damage than the onset of shoot emissions. The shoots of double infested plants also emitted higher levels of methanol. Thus, interactive effects of root and shoot herbivores exhibit more strongly in the VOC emissions from the shoots than from the roots, implying the involvement of specific signaling interactions.

  6. Emissions of Monoterpenes and DMS from Corn and their Influence on Nighttime Chemical Processing of Nitrogen Oxides

    NASA Astrophysics Data System (ADS)

    Graus, M.; De Gouw, J. A.; Brown, S. S.; Williams, E. J.; Eller, A. S.; Gilman, J. B.; Lerner, B. M.; Fall, R.; Warneke, C.

    2012-12-01

    In the United States large amounts of corn are grown for the use as animal feed, for the food industry and for the production of fuel ethanol. In 2012 the acreage of corn planted was 390,000 km2 covering over 4.2% of the US land surface. The BioCORN 2011 field experiment took place in summer 2011 to look at ecosystem fluxes of volatile organic compounds (VOCs) from a cornfield in Colorado during the period of rapid biomass increase and the development of flowers and ears. Eddy covariance, soil and leaf cuvette measurements using various instruments including PTR-MS, NI-PT-CIMS and GC-MS were used to determine fluxes of VOCs, CO2 and NOx. Corn plants emit significant amounts of VOCs with methanol being the largest emission and smaller emissions of other VOCs such acetone, acetaldehyde, monoterpene and dimethylsulfide (DMS). During the day VOCs mainly react with hydroxyl radicals and during the night with nitrate radicals (NO3), where emissions from corn may act as a sink for reactive nitrogen. DMS, mainly emitted from oceans and to a lesser extent from terrestrial vegetation, had a diurnal cycle: mixing ratios high during the night, but fluxes high during the day. DMS was found to dominate the reactivity of NO3 followed by monoterpenes and the heterogeneous loss of N2O5, which has implications for the nighttime chemistry. Other results of BioCORN 2011 on VOC emissions from corn and their impact on atmospheric chemistry will be presented and discussed.

  7. Metabolomics and the Legacy of Previous Ecosystems: a Case Study from the Brine of Lake Vida (Antarctica)

    NASA Astrophysics Data System (ADS)

    Chou, L.; Kenig, F. P. H.; Murray, A. E.; Doran, P. T.; Fritsen, C. H.

    2015-12-01

    The McMurdo Dry Valleys of Antarctica are regarded as one of the best Earth analogs for astrobiological investigations of icy worlds. In the dry valleys, Lake Vida contains an anoxic and aphotic ice-sealed brine that has been isolated for millennia and yet is hosting a population of active microbes at -13˚ C. The biogeochemical processes used by these slow-growing microbes are still unclear. We attempt to elucidate the microbial processes responsible for the survivability of these organisms using metabolomics. Preliminary investigations of organic compounds of Lake Vida Brine (LVBr) was performed using gas chromatography-mass spectrometry (GC-MS) and solid-phase micro-extraction (SPME) GC-MS. LVBr contains a vast variety of lipids and is dominated by low molecular weight compounds. Many of these compounds are biomarkers of processes that took place in Lake Vida prior to evaporation and its cryo-encapsulation. These compounds include dimethylsulfide that is derived from the photosynthate dimethylsulfoniopropionate, dihydroactinidiolide that is derived from a diatom pigment, and 2-methyl-3-ethyl-maleimide that is derived from chlorophyll. These compounds, which dominate the lipid reservoir, represent a legacy from an ecosystem that is different from the current bacterial ecosystem of the brine. The abundance of the legacy compounds in the brine is most likely a reflection of the very slow metabolism of the bacterial community in the cold brine. It is important, thus, to be able to distinguish the legacy metabolites and their diagenetic products from the metabolites of the current ecosystem. This legacy issue is specific to a slow growing microbial ecosystem that cannot process the legacy carbon completely. It applies not only to Lake Vida brine, but other slow growing ecosystems such as other subglacial Antarctic lakes, the Arctic regions, and the deep biosphere.

  8. Metabolism of reduced methylated sulfur compounds in anaerobic sediments and by a pure culture of an estuarine methanogen

    USGS Publications Warehouse

    Kiene, R.P.; Oremland, Ronald S.; Catena, Anthony; Miller, Laurence G.; Capone, D.G.

    1986-01-01

    Addition of dimethylsulfide (DMS), dimethyldisulfide (DMDS), or methane thiol (MSH) to a diversity of anoxic aquatic sediments (e.g., fresh water, estuarine, alkaline/hypersaline) stimulated methane production. The yield of methane recovered from DMS was often 52 to 63%, although high concentrations of DMS (as well as MSH and DMDS) inhibited methanogenesis in some types of sediments. Production of methane from these reduced methylated sulfur compounds was blocked by 2-bromoethanesulfonic acid. Sulfate did not influence the metabolism of millimolar levels of DMS, DMDS, or MSH added to sediments. However, when DMS was added at ∼2-μM levels as [14C]DMS, metabolism by sediments resulted in a 14CH4/14CO2 ratio of only 0.06. Addition of molybdate increased the ratio to 1.8, while 2-bromoethanesulfonic acid decreased it to 0, but did not block 14CO2 production. These results indicate the methanogens and sulfate reducers compete for DMS when it is present at low concentrations; however, at high concentrations, DMS is a “noncompetitive” substrate for methanogens. Metabolism of DMS by sediments resulted in the appearance of MSH as a transient intermediate. A pure culture of an obligately methylotrophic estuarine methanogen was isolated which was capable of growth on DMS. Metabolism of DMS by the culture also resulted in the transient appearance of MSH, but the organism could grow on neither MSH nor DMDS. The culture metabolized [14C]-DMS to yield a 14CH4/14CO2 ratio of ∼2.8. Reduced methylated sulfur compounds represent a new class of substrates for methanogens and may be potential precursors of methane in a variety of aquatic habitats.

  9. Do oceanic emissions account for the missing source of atmospheric carbonyl sulfide?

    NASA Astrophysics Data System (ADS)

    Lennartz, Sinikka; Marandino, Christa A.; von Hobe, Marc; Cortés, Pau; Simó, Rafel; Booge, Dennis; Quack, Birgit; Röttgers, Rüdiger; Ksionzek, Kerstin; Koch, Boris P.; Bracher, Astrid; Krüger, Kirstin

    2016-04-01

    Carbonyl sulfide (OCS) has a large potential to constrain terrestrial gross primary production (GPP), one of the largest carbon fluxes in the carbon cycle, as it is taken up by plants in a similar way as CO2. To estimate GPP in a global approach, the magnitude and seasonality of sources and sinks of atmospheric OCS have to be well understood, to distinguish between seasonal variation caused by vegetation uptake and other sources or sinks. However, the atmospheric budget is currently highly uncertain, and especially the oceanic source strength is debated. Recent studies suggest that a missing source of several hundreds of Gg sulfur per year is located in the tropical ocean by a top-down approach. Here, we present highly-resolved OCS measurements from two cruises to the tropical Pacific and Indian Ocean as a bottom-up approach. The results from these cruises show that opposite to the assumed ocean source, direct emissions of OCS from the tropical ocean are unlikely to account for the missing source. To reduce uncertainty in the global oceanic emission estimate, our understanding of the production and consumption processes of OCS and its precursors, dimethylsulfide (DMS) and carbon disulphide (CS2), needs improvement. Therefore, we investigate the influence of dissolved organic matter (DOM) on the photochemical production of OCS in seawater by considering analysis of the composition of DOM from the two cruises. Additionally, we discuss the potential of oceanic emissions of DMS and CS2 to closing the atmospheric OCS budget. Especially the production and consumption processes of CS2 in the surface ocean are not well known, thus we evaluate possible photochemical or biological sources by analyzing its covariation of biological and photochemical parameters.

  10. Dust in an acidified ocean: iron bioavailability, phytoplankton growth and DMS

    NASA Astrophysics Data System (ADS)

    Mélançon, J.; Levasseur, M.; Lizotte, M.; Scarratt, M. G.; Tremblay, J. E.; Tortell, P. D.; Yang, G.; Shi, G. Y.; Gao, H.; Semeniuk, D.; Robert, M.; Arychuk, M.; Johnson, K.; Sutherland, N.; Davelaar, M.; Nemcek, N.; Pena, A.; Richardson, W.

    2015-12-01

    Ocean acidification (OA) is likely to have an effect on the fertilizing potential of desert dust in high-nutrient, low-chlorophyll oceanic regions, either by modifying Fe speciation and bioavailability, or by altering phytoplankton Fe requirements and acquisition. To address this issue, short incubations (4 days) of northeast subarctic Pacific waters enriched with either FeSO4 or dust, and maintained at pH 8.0 (in situ) and 7.8 were conducted in August 2010. We assessed the impact of a decrease in pH on dissolved Fe concentration, phytoplankton biomass, taxonomy and productivity, and the production of dimethylsulfide (DMS) and its algal precursor dimethylsulfoniopropionate (DMSP). Chlorophyll a (chl a) remained unchanged in the controls and doubled in both the FeSO4-enriched and dust-enriched incubations, confirming the Fe-limited status of the plankton assemblage during the experiment. In the acidified treatments, a significant reduction (by 16-38%) of the final concentration of chl a was measured compared to their non-acidified counterparts, and a 15% reduction in particulate organic carbon (POC) concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched non-acidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria. Lowering the pH affected mostly the haptophytes, but pelagophyte concentrations were also reduced in some acidified treatments. Acidification did not significantly alter DMSP and DMS concentrations. These results show that dust deposition events in a low-pH iron-limited Northeast subarctic Pacific are likely to stimulate phytoplankton growth to a lesser extent than in today's ocean during the few days following fertilization and point to a low initial sensitivity of the DMSP and DMS dynamics to OA.

  11. Effects of dust additions on phytoplankton growth and DMS production in high CO2 northeast Pacific HNLC waters

    NASA Astrophysics Data System (ADS)

    Mélançon, J.; Levasseur, M.; Lizotte, M.; Scarratt, M.; Tremblay, J.-É.; Tortell, P.; Yang, G.-P.; Shi, G.-Y.; Gao, H.-W.; Semeniuk, D. M.; Robert, M.; Arychuk, M.; Johnson, K.; Sutherland, N.; Davelaar, M.; Nemcek, N.; Peña, A.; Richardson, W.

    2015-08-01

    Ocean acidification (OA) is likely to have an effect on the fertilizing potential of desert dust in high-nutrient, low-chlorophyll oceanic regions, either by modifying Fe speciation and bioavailability, or by altering phytoplankton Fe requirements and acquisition. To address this issue, short incubations (4 days) of northeast subarctic Pacific waters enriched with either FeSO4 or dust, and set at pH 8.0 (in situ) and 7.8 were conducted in August 2010. We assessed the impact of a decrease in pH on dissolved Fe concentration, phytoplankton biomass, taxonomy and productivity, and the production of dimethylsulfide (DMS) and its algal precursor dimethylsulfoniopropionate (DMSP). Chlorophyll a (chl a) remained unchanged in the controls and doubled in both the FeSO4-enriched and dust-enriched incubations, confirming the Fe-limited status of the plankton assemblage during the experiment. In the acidified treatments, a significant reduction (by 16-38 %) of the final concentration of chl a was measured compared to their non-acidified counterparts, and a 15 % reduction in particulate organic carbon (POC) concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched non-acidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria. Lowering the pH affected mostly the haptophytes, but pelagophyte concentrations were also reduced in some acidified treatments. Acidification did not significantly alter DMSP and DMS concentrations. These results show that dust deposition events in a low-pH iron-limited Northeast subarctic Pacific are likely to stimulate phytoplankton growth to a lesser extent than in today's ocean during the few days following fertilization and point to a low initial sensitivity of the DMSP and DMS dynamics to OA.

  12. Biogenic influence on cloud microphysics over the global ocean

    NASA Astrophysics Data System (ADS)

    Lana, A.; Simó, R.; Vallina, S. M.; Dachs, J.

    2012-02-01

    Aerosols have a large potential to influence climate through their effects on the microphysics and optical properties of clouds and, hence, on the Earth's radiation budget. Aerosol-cloud interactions have been intensively studied in polluted air, but the possibility that the marine biosphere plays a role in regulating cloud brightness in the pristine oceanic atmosphere remains largely unexplored. We used 9 yr of global satellite data and ocean climatologies to derive parameterizations of (a) production fluxes of sulfur aerosols formed by the oxidation of the biogenic gas dimethylsulfide emitted from the sea surface; (b) production fluxes of secondary organic aerosols from biogenic organic volatiles; (c) emission fluxes of biogenic primary organic aerosols ejected by wind action on sea surface; and (d) emission fluxes of sea salt also lifted by the wind upon bubble bursting. Series of global weekly estimates of these fluxes were correlated to series of cloud droplet effective radius data derived from satellite (MODIS). Similar analyses were conducted in more detail at 6 locations spread among polluted and clean regions of the oceanic atmosphere. The outcome of the statistical analysis was that negative correlation was common at mid and high latitude for sulfur and organic secondary aerosols, indicating both might be important in seeding cloud droplet activation. Conversely, primary aerosols (organic and sea salt) showed more variable, non-significant or positive correlations, indicating that, despite contributing to large shares of the marine aerosol mass, they are not major drivers of the variability of cloud microphysics. Uncertainties and synergisms are discussed, and recommendations of research needs are given.

  13. Studies of sulfur biogeochemistry, microbiology and paleontology in three anoxic environments: The Black Sea, a salt marsh mat, and an Ordovician black shale

    SciTech Connect

    Muramoto, J.A.

    1992-01-01

    The author studied the biogeochemistry, microbial ecology and paleontology of three anoxic environments. In the Black Sea, three studies dealt with the role of particle fluxes in sulfur cycling and microbial ecology. In the water column, iron sulfides form at the oxic-anoxic interface from dissolved sulfide left after chemical oxidation, based on sulfur isotopes; formation in deep water is minimal and iron-limited. Sinking organic aggregates transport iron sulfides to the bottom. Sedimentary sulfides may originate from sulfide fluxes and record intensity of chemical vs. microbial oxidation at the oxic-anoxic interface. Sulfate reduction rates from modelled diagenesis of organic carbon fluxes agree with other measured rates. A box model summarizes sulfur cycling between water column and sediments. An algal sulfur compound, dimethylsulfoniopropionate (DMSP), precursor to dimethylsulfide (DMS), was measured in deep-sea particle fluxes. DMSP levels in particle fluxes vary seasonally and between oceans. Though DMSP is only 0.005% of organic carbon fluxes, its removal to the deep sea by fluxes may lessen sea-air DMS fluxes. A DMSP-DMS cycle for ocean and sediments is proposed. A third study compared bacteria biomass and morphology in particle fluxes and water column, using TEM and epifluorescence microscopy. Some bacteria had intracellular structures indicating autotrophy. Concentrations in particle fluxes were high compared to sediment bacteria populations elsewhere, but bacterial carbon is a tiny fraction of total organic carbon. In contrast, phototrophic bacteria dominated a microbial mat in a salt marsh where sulfate reduction is important. Cyanobacteria, purple and green sulfur bacteria species were strongly depth-zoned, and cell sizes decreased as depth increased. Also investigated was spatiotemporal change in a fossil lingulid brachiopod from a suboxic facies, using gradient analyses of benthic invertebrate and planktonic graptolite assemblages.

  14. A Satellite-Based Method for Estimating Global Oceanic DMS and Its Application in a 3-D Atmospheric GCM

    SciTech Connect

    Belviso, S.; Moulin, C.; Bopp, L.; Cosme, E.; Chapman, Elaine G.; Aranami, K.

    2003-01-01

    The flux of dimethylsulfide (DMS) from the world's oceans is the largest known source of biogenically-derived reduced sulfur compounds to the atmosphere. Its impact on atmospheric chemistry and radiative transfer is an active area of scientific research, and DMS is routinely included in three-dimensional global climate change and chemical transport models. In such models, DMS fluxes typically are based on global sea surface DMS concentrations and wind-speed-dependent parameterizations of the mass transfer coefficient. We show here how sea surface DMS concentrations can be estimated from satellite-based Sea-viewing Wide Field-of-View Sensor (SeaWiFS) observations of sea surface chlorophyll a. We compare SeaWiFS-derived DMS concentrations for the twelve month period November 1997 through October 1998 with shipboard measurements made in the Pacific and Indian Oceans. The SeaWiFS-derived DMS distributions demonstrate improved capture of DMS spatial variability in Southern Ocean surface waters relative to previous works, but underestimate the amplitude of seasonal DMS variations in this region. Using the three-dimensional Atmospheric General Circulation Model of the Laboratoire de M?orologie Dynamique, model-time-step wind speeds, an atmospheric-stability-dependent parameterization of the mass transfer coefficient, and our SeaWiFS-derived oceanic DMS distributions, we estimate an annual Southern Ocean DMS emission of 6.8 Tg S yr-1. This value represents approximately one-third of the annual global DMS marine emission, and underscores the importance of this region as a source of natural sulfur emissions.

  15. Coccolithophores and the Merchant Fishing Corps Along Northern California Shores: Atmospheric Monitoring of DMS and CO at the Bodega Marine Lab

    NASA Astrophysics Data System (ADS)

    Faloona, I.; Day, D.; Choi, W.; Cox, E.

    2005-12-01

    Two major science steering documents have explicitly identified the importance of the coastal oceans in Earth systems science - the North American Carbon Plan and The Ocean Carbon & Climate Change implementation strategy, and both emphasize the need to augment current monitoring networks in these environments. The Northern California coast is a particularly interesting locale because of the intense upwelling induced there by strong northerly flow leeward of the Pacific High during the spring and summer. This upwelling system, and some four others like it around the globe, sustain the most ecologically bountiful regions in the marine biosphere, and collectively are responsible for almost half of the world's fish catch. There is also some concern about the response of these critically important ecosystems to global climate change. We are operating a continuous, high-rate CO instrument at the Bodega Marine Lab on the Northern California coast in order to better understand and quantify regional sources that may influence what is commonly considered to be the North American background atmosphere. Inspection of the high resolution CO time series reveals frequent spikes during onshore flow thought to represent ship plumes advecting past the sensor. Analysis of these data has rendered an estimate of the CO emissions from local ship traffic, while measurements of dissolved CO in the ocean permit an estimate of the natural emissions from coastal waters. Moreover, a pilot study measuring atmospheric dimethylsulfide (DMS) during July and August, 2005 indicates concentrations ranging from 30 to 1,300 pptv, confirming that this site is a unique one. We will show some of the main meteorological and sea state variables that control the emissions of these important biogeochemical species, and estimate their contribution to the total CO and aerosol sulfur loading in the coastal boundary layer, all the while emphasizing the unique importance of this monitoring station.

  16. Spatial variation of biogenic sulfur in the south Yellow Sea and the East China Sea during summer and its contribution to atmospheric sulfate aerosol.

    PubMed

    Zhang, Sheng-Hui; Yang, Gui-Peng; Zhang, Hong-Hai; Yang, Jian

    2014-08-01

    Spatial distributions of biogenic sulfur compounds including dimethylsulfide (DMS), dissolved and particulate dimethylsulfoniopropionate (DMSPd and DMSPp) were investigated in the South Yellow Sea (SYS) and the East China Sea (ECS) in July 2011. The concentrations of DMS and DMSPp were significantly correlated with the levels of chlorophyll a in the surface water. Simultaneously, relatively high ratio values of DMSP/chlorophyll a and DMS/chlorophyll a occurred in the areas where the phytoplankton community was dominated by dinoflagellates. The DMSPp and chlorophyll a size-fractionation showed that larger nanoplankton (5-20 μm) was the most important producer of DMSPp in the study area. The vertical profiles of DMS and DMSP were characterized by a maximum at the upper layer and the bottom concentrations were also relatively higher compared with the overlying layer of the bottom. In addition, a positive linear correlation was observed between dissolved dimethylsulfoxide (DMSOd) and DMS concentrations in the surface waters. The sea-to-air fluxes of DMS in the study area were estimated to be from 0.03 to 102.35 μmol m(-2) d(-1) with a mean of 16.73 μmol m(-2) d(-1) and the contribution of biogenic non-sea-salt SO4(2-) (nss-SO4(2-)) to the measured total nss-SO4(2-) in the atmospheric aerosol over the study area varied from 1.42% to 30.98%, with an average of 8.2%.

  17. Impact of ocean acidification on phytoplankton assemblage, growth, and DMS production following Fe-dust additions in the NE Pacific high-nutrient, low-chlorophyll waters

    NASA Astrophysics Data System (ADS)

    Mélançon, Josiane; Levasseur, Maurice; Lizotte, Martine; Scarratt, Michael; Tremblay, Jean-Éric; Tortell, Philippe; Yang, Gui-Peng; Shi, Guang-Yu; Gao, Huiwang; Semeniuk, David; Robert, Marie; Arychuk, Michael; Johnson, Keith; Sutherland, Nes; Davelaar, Marty; Nemcek, Nina; Peña, Angelica; Richardson, Wendy

    2016-03-01

    Ocean acidification (OA) is likely to have an effect on the fertilizing potential of desert dust in high-nutrient, low-chlorophyll oceanic regions, either by modifying iron (Fe) speciation and bioavailability or by altering phytoplankton Fe requirements and acquisition. To address this issue, short incubations (4 days) of northeast subarctic Pacific waters enriched with either FeSO4 or dust and set at pH 8.0 (in situ) and 7.8 were conducted in August 2010. We assessed the impact of a decrease in pH on dissolved Fe concentration, phytoplankton biomass, taxonomy and productivity, and the production of dimethylsulfide (DMS) and its algal precursor dimethylsulfoniopropionate (DMSP). Chlorophyll a (chl a) remained unchanged in the controls and doubled in both the FeSO4-enriched and dust-enriched incubations, confirming the Fe-limited status of the plankton assemblage during the experiment. In the acidified treatments, a significant reduction (by 16-38 %) in the final concentration of chl a was measured compared to their nonacidified counterparts, and a 15 % reduction in particulate organic carbon (POC) concentration was measured in the dust-enriched acidified treatment compared to the dust-enriched nonacidified treatment. FeSO4 and dust additions had a fertilizing effect mainly on diatoms and cyanobacteria as estimated from algal pigment signatures. Lowering the pH affected mostly the haptophytes, but pelagophyte concentrations were also reduced in some acidified treatments. Acidification did not significantly alter DMSP and DMS concentrations. These results show that dust deposition events in a low-pH iron-limited northeast subarctic Pacific are likely to stimulate phytoplankton growth to a lesser extent than in today's ocean during the few days following fertilization and point to a low initial sensitivity of the DMSP and DMS dynamics to OA.

  18. A meta-analysis of oceanic DMS and DMSP cycling processes: Disentangling the summer paradox

    NASA Astrophysics Data System (ADS)

    Galí, Martí; Simó, Rafel

    2015-04-01

    The biogenic volatile compound dimethylsulfide (DMS) is produced in the ocean mainly from the ubiquitous phytoplankton osmolyte dimethylsulfoniopropionate (DMSP). In the upper mixed layer, DMS concentration and the daily averaged solar irradiance are roughly proportional across latitudes and seasons. This translates into a seasonal mismatch between DMS and phytoplankton biomass at low latitudes, termed the "DMS summer paradox," which remains difficult to reproduce with biogeochemical models. Here we report on a global meta-analysis of DMSP and DMS cycling processes and their relationship to environmental factors. We show that DMS seasonality reflects progressive changes in a short-term dynamic equilibrium, set by the quotient between gross DMS production rates and the sum of biotic and abiotic DMS consumption rate constants. Gross DMS production is the principal driver of DMS seasonality, due to the synergistic increases toward summer in two of its underlying factors: phytoplankton DMSP content (linked to species succession) and short-term community DMSP-to-DMS conversion yields (linked to physiological stress). We also show that particulate DMSP transformations (linked to grazing-induced phytoplankton mortality) generally contribute a larger share of gross DMS production than dissolved-phase DMSP metabolism. The summer paradox is amplified by a decrease in microbial DMS consumption rate constants toward summer. However, this effect is partially compensated by a concomitant increase in abiotic DMS loss rate constants. Besides seasonality, we identify consistent covariation between key sulfur cycling variables and trophic status. These findings should improve the modeling projections of the main natural source of climatically active atmospheric sulfur.

  19. Effect of a variety of Chinese herbs and an herb-containing dentifrice on volatile sulfur compounds associated with halitosis: An in vitro analysis

    PubMed Central

    Li, Ming-yu; Wang, Jun; Xu, Zhu-ting

    2010-01-01

    Background: The principal components of halitosis are volatile sulfur compounds (VSCs) such as hydrogen sulfide, methyl mercaptan, and dimethylsulfide or compounds such as butyric acid, propionic acid, putrescine, and cadaverine. Objective: The aim of this study was to evaluate the effect of Chinese herbs on VSCs in vitro. Methods: Saliva samples from volunteers were used as the source for the evaluation of bacterial activity and VSC inhibition. Extracted substances from Chinese herbs were identified by VSC inhibition tests with a Halimeter and microbial sensitivity testing. The effectiveness on halitosis was compared between a dentifrice containing one of the effective Chinese herbs (ie, chrysanthemum flower [Chrysanthemum morifolium flos]), 4 commercially available antihalitosis dentifrices, and a positive control that received no treatment. Results: Ten volunteers provided saliva samples for VSC testing. Of the 40 herbs tested, 14 extracts had percent inhibition rates of VSCs >50%. Ten herbs showed greatest effect against all culturable microorganisms with bacterial inhibition >70%. There was a weak positive correlation between bacteriostasis and the anti-VSC activity of the herbs with a correlation coefficient of 0.2579 (Pearson). The mean (SD) values of the VSC testing were as follows: dentifrice containing chrysanthemum flower, 55.91 (8.16) ppb; Crest Tea Refreshing Dentifrice®, 48.39 (7.48) ppb (P = NS); Cortex Phellodendri Dentifrice®, 139.90 (14.70) ppb (P < 0.01); Colgate Total Plus Whitening®, 120.94 (15.58) ppb (P < 0.01); Zhong Hua Chinese Herbs Dentifrice®, 136.96 (13.06) ppb (P < 0.01); and positive control, 312.38 (28.58) ppb (P < 0.01). Conclusions: Of 40 herbs tested, 14 Chinese herbs were found to be effective for VSC inhibition. A dentifrice containing chrysanthemum flower reduced the formation of VSC in vitro, showing a significantly greater effect than the control group and 3 of 4 dentifrices already on the market. PMID:24683259

  20. Volatile metabolites of higher plant crops as a photosynthesizing life support system component under temperature stress at different light intensities

    NASA Astrophysics Data System (ADS)

    Gitelson, I. I.; Tikhomirov, A. A.; Parshina, O. V.; Ushakova, S. A.; Kalacheva, G. S.

    The effect of elevated temperatures of 35 and 45°C (at the intensities of photosynthetically active radiation 322, 690 and 1104 μmol·m -2·s -1) on the photosynthesis, respiration, and qualitative and quantitative composition of the volatiles emitted by wheat ( Triticum aestuvi L., cultivar 232) crops was investigated in growth chambers. Identification and quantification of more than 20 volatile compounds (terpenoids-α-pinene, Δ3 carene, limonene, benzene, α-and trans-caryophyllene, α- and γ-terpinene, their derivatives, aromatic hydrocarbons, etc.) were conducted by gas chromatograph/mass spectrometry. Under light intensity of 1104 μmol·m -2·s -1 heat resistance of photosynthesis and respiration increased at 35°C and decreased at 45°C. The action of elevated temperatures brought about variations in the rate and direction of the synthesis of volatile metabolites. The emission of volatile compounds was the greatest under a reduced irradiation of 322 μmol·m -2·s -1 and the smallest under 1104 μmol·m -2·s -1, at 35°C. During the repair period, the contents and proportions of volatile compounds were different from their initial values, too. The degree of disruption and the following recovery of the functional state depended on the light intensity during the exposure to elevated temperatures. The investigation of the atmosphere of the growth chamber without plants has revaled the substances that were definitely technogenic in origin: tetramethylurea, dimethylsulfide, dibutylsulfide, dibutylphthalate, and a number of components of furan and silane nature.

  1. Explicit solvent simulations of the aqueous oxidation potential and reorganization energy for neutral molecules: gas phase, linear solvent response, and non-linear response contributions.

    PubMed

    Guerard, Jennifer J; Tentscher, Peter R; Seijo, Marianne; Samuel Arey, J

    2015-06-14

    First principles simulations were used to predict aqueous one-electron oxidation potentials (Eox) and associated half-cell reorganization energies (λaq) for aniline, phenol, methoxybenzene, imidazole, and dimethylsulfide. We employed quantum mechanical/molecular mechanical (QM/MM) molecular dynamics (MD) simulations of the oxidized and reduced species in an explicit aqueous solvent, followed by EOM-IP-CCSD computations with effective fragment potentials for diabatic energy gaps of solvated clusters, and finally thermodynamic integration of the non-linear solvent response contribution using classical MD. A priori predicted Eox and λaq values exhibit mean absolute errors of 0.17 V and 0.06 eV, respectively, compared to experiment. We also disaggregate Eox into several well-defined free energy properties, including the gas phase adiabatic free energy of ionization (7.73 to 8.82 eV), the solvent-induced shift in the free energy of ionization due to linear solvent response (-2.01 to -2.73 eV), and the contribution from non-linear solvent response (-0.07 to -0.14 eV). The linear solvent response component is further apportioned into contributions from the solvent-induced shift in vertical ionization energy of the reduced species (ΔVIEaq) and the solvent-induced shift in negative vertical electron affinity of the ionized species (ΔNVEAaq). The simulated ΔVIEaq and ΔNVEAaq are found to contribute the principal sources of uncertainty in computational estimates of Eox and λaq. Trends in the magnitudes of disaggregated solvation properties are found to correlate with trends in structural and electronic features of the solute. Finally, conflicting approaches for evaluating the aqueous reorganization energy are contrasted and discussed, and concluding recommendations are given.

  2. Chemical Speciation of Sulfur in Marine Cloud Droplets and Particles: 1. Analysis of Individual Particles Using Complementary Microprobe Methods.

    NASA Astrophysics Data System (ADS)

    Desyaterik, Y.; Hopkins, R. J.; Tivanski, A. V.; Berkowitz, C. M.; Gilles, M. K.; Laskin, A.

    2006-12-01

    Chemical speciation of dry residues of individual cloud droplets and interstitial aerosol collected from sea-fog during the Marine Stratus Experiment (MASE) in July 2005 was facilitated using a complementary combination of computer controlled scanning electron microscopy with energy dispersed analysis of x-rays (CCSEM/EDX), time-of-flight secondary ionization mass spectrometry (TOF-SIMS), and scanning transmission x-ray microscopy with near edge x-ray absorption fine structure spectroscopy (STXM/NEXAFS). Particle samples were collected at the ground site located in Pt. Reyes National Seashore, about 0.5 miles from the ocean coast over the period of time when the air plume, that originated over the open ocean, passed the area of the cold stream along the northern California coast. Based on composition, morphology, and microstructure, two externally mixed, distinct types of sea-fog particles were identified in the samples: chemically modified (aged) sea salt particles and secondary formed sulfate particles. The results indicate excessive formation of methanesulfonate (CH3SO3-) rather then non-sea-salt sulfate (nss-SO42-) in the sea salt particles. This observation is consistent with the recent modeling studies of dimethylsulfide (DMS) oxidation chemistry in the marine boundary layer (MDL). Modeling studies predict enhanced formation of CH3SO3- in activated sea salt particles under cloudy MBL conditions over the areas with low ocean surface temperatures. We discuss the climate related effects of this chemistry which likely results in: a) increasing size and hygroscopicity of the pre-existing CCN (sea salt particles), and b) reducing the production of gaseous H2SO4 and subsequent new sulfate particle formation.

  3. Transsulfuration in an adult with hepatic methionine adenosyltransferase deficiency.

    PubMed Central

    Gahl, W A; Bernardini, I; Finkelstein, J D; Tangerman, A; Martin, J J; Blom, H J; Mullen, K D; Mudd, S H

    1988-01-01

    We investigated sulfur and methyl group metabolism in a 31-yr-old man with partial hepatic methionine adenosyltransferase (MAT) deficiency. The patient's cultured fibroblasts and erythrocytes had normal MAT activity. Hepatic S-adenosylmethionine (SAM) was slightly decreased. This clinically normal individual lives with a 20-30-fold elevation of plasma methionine (0.72 mM). He excretes in his urine methionine and L-methionine-d-sulfoxide (2.7 mmol/d), a mixed disulfide of methanethiol and a thiol bound to an unidentified group X, which we abbreviate CH3S-SX (2.1 mmol/d), and smaller quantities of 4-methylthio-2-oxobutyrate and 3-methylthiopropionate. His breath contains 17-fold normal concentrations of dimethylsulfide. He converts only 6-7 mmol/d of methionine sulfur to inorganic sulfate. This abnormally low rate is due not to a decreased flux through the primarily defective enzyme, MAT, since SAM is produced at an essentially normal rate of 18 mmol/d, but rather to a rate of homocysteine methylation which is abnormally high in the face of the very elevated methionine concentrations demonstrated in this patient. These findings support the view that SAM (which is marginally low in this patient) is an important regulator that helps to determine the partitioning of homocysteine between degradation via cystathionine and conservation by reformation of methionine. In addition, these studies demonstrate that the methionine transamination pathway operates in the presence of an elevated body load of that amino acid in human beings, but is not sufficient to maintain methionine levels in a normal range. PMID:3339126

  4. Biochemical, Kinetic, and Spectroscopic Characterization of Ruegeria pomeroyi DddW—A Mononuclear Iron-Dependent DMSP Lyase

    PubMed Central

    Brummett, Adam E.; Schnicker, Nicholas J.; Crider, Alexander; Todd, Jonathan D.; Dey, Mishtu

    2015-01-01

    The osmolyte dimethylsulfoniopropionate (DMSP) is a key nutrient in marine environments and its catabolism by bacteria through enzymes known as DMSP lyases generates dimethylsulfide (DMS), a gas of importance in climate regulation, the sulfur cycle, and signaling to higher organisms. Despite the environmental significance of DMSP lyases, little is known about how they function at the mechanistic level. In this study we biochemically characterize DddW, a DMSP lyase from the model roseobacter Ruegeria pomeroyi DSS-3. DddW is a 16.9 kDa enzyme that contains a C-terminal cupin domain and liberates acrylate, a proton, and DMS from the DMSP substrate. Our studies show that as-purified DddW is a metalloenzyme, like the DddQ and DddP DMSP lyases, but contains an iron cofactor. The metal cofactor is essential for DddW DMSP lyase activity since addition of the metal chelator EDTA abolishes its enzymatic activity, as do substitution mutations of key metal-binding residues in the cupin motif (His81, His83, Glu87, and His121). Measurements of metal binding affinity and catalytic activity indicate that Fe(II) is most likely the preferred catalytic metal ion with a nanomolar binding affinity. Stoichiometry studies suggest DddW requires one Fe(II) per monomer. Electronic absorption and electron paramagnetic resonance (EPR) studies show an interaction between NO and Fe(II)-DddW, with NO binding to the EPR silent Fe(II) site giving rise to an EPR active species (g = 4.29, 3.95, 2.00). The change in the rhombicity of the EPR signal is observed in the presence of DMSP, indicating that substrate binds to the iron site without displacing bound NO. This work provides insight into the mechanism of DMSP cleavage catalyzed by DddW. PMID:25993446

  5. Sulfonium Ion Derivatization, Isobaric Stable Isotope Labeling and Data Dependent CID- and ETD-MS/MS for Enhanced Phosphopeptide Quantitation, Identification and Phosphorylation Site Characterization

    PubMed Central

    Lu, Yali; Zhou, Xiao; Stemmer, Paul M.; Reid, Gavin E.

    2014-01-01

    An amine specific peptide derivatization strategy involving the use of novel isobaric stable isotope encoded ‘fixed charge’ sulfonium ion reagents, coupled with an analysis strategy employing capillary HPLC, ESI-MS, and automated data dependent ion trap CID-MS/MS, -MS3, and/or ETD-MS/MS, has been developed for the improved quantitative analysis of protein phosphorylation, and for identification and characterization of their site(s) of modification. Derivatization of 50 synthetic phosphopeptides with S,S′-dimethylthiobutanoylhydroxysuccinimide ester iodide (DMBNHS), followed by analysis using capillary HPLC-ESI-MS, yielded an average 2.5-fold increase in ionization efficiencies and a significant increase in the presence and/or abundance of higher charge state precursor ions compared to the non-derivatized phosphopeptides. Notably, 44% of the phosphopeptides (22 of 50) in their underivatized states yielded precursor ions whose maximum charge states corresponded to +2, while only 8% (4 of 50) remained at this maximum charge state following DMBNHS derivatization. Quantitative analysis was achieved by measuring the abundances of the diagnostic product ions corresponding to the neutral losses of ‘light’ (S(CH3)2) and ‘heavy’ (S(CD3)2) dimethylsulfide exclusively formed upon CID-MS/MS of isobaric stable isotope labeled forms of the DMBNHS derivatized phosphopeptides. Under these conditions, the phosphate group stayed intact. Access for a greater number of peptides to provide enhanced phosphopeptide sequence identification and phosphorylation site characterization was achieved via automated data-dependent CID-MS3 or ETD-MS/MS analysis due to the formation of the higher charge state precursor ions. Importantly, improved sequence coverage was observed using ETD-MS/MS following introduction of the sulfonium ion fixed charge, but with no detrimental effects on ETD fragmentation efficiency. PMID:21952753

  6. Trimethylamine and Organic Matter Additions Reverse Substrate Limitation Effects on the δ13C Values of Methane Produced in Hypersaline Microbial Mats

    PubMed Central

    Nicholson, Brooke E.; Beaudoin, Claire S.; Detweiler, Angela M.; Bebout, Brad M.

    2014-01-01

    Methane production has been observed in a number of hypersaline environments, and it is generally thought that this methane is produced through the use of noncompetitive substrates, such as the methylamines, dimethylsulfide and methanol. Stable isotope measurements of the produced methane have also suggested that the methanogens are operating under conditions of substrate limitation. Here, substrate limitation in gypsum-hosted endoevaporite and soft-mat hypersaline environments was investigated by the addition of trimethylamine, a noncompetitive substrate for methanogenesis, and dried microbial mat, a source of natural organic matter. The δ13C values of the methane produced after amendments were compared to those in unamended control vials. At all hypersaline sites investigated, the δ13C values of the methane produced in the amended vials were statistically lower (by 10 to 71‰) than the unamended controls, supporting the hypothesis of substrate limitation at these sites. When substrates were added to the incubation vials, the methanogens within the vials fractionated carbon isotopes to a greater degree, resulting in the production of more 13C-depleted methane. Trimethylamine-amended samples produced lower methane δ13C values than the mat-amended samples. This difference in the δ13C values between the two types of amendments could be due to differences in isotope fractionation associated with the dominant methane production pathway (or substrate used) within the vials, with trimethylamine being the main substrate used in the trimethylamine-amended vials. It is hypothesized that increased natural organic matter in the mat-amended vials would increase fermentation rates, leading to higher H2 concentrations and increased CO2/H2 methanogenesis. PMID:25239903

  7. Bacterial Catabolism of Dimethylsulfoniopropionate (DMSP)

    PubMed Central

    Reisch, Chris R.; Moran, Mary Ann; Whitman, William B.

    2011-01-01

    Dimethylsulfoniopropionate (DMSP) is a metabolite produced primarily by marine phytoplankton and is the main precursor to the climatically important gas dimethylsulfide (DMS). DMS is released upon bacterial catabolism of DMSP, but it is not the only possible fate of DMSP sulfur. An alternative demethylation/demethiolation pathway results in the eventual release of methanethiol, a highly reactive volatile sulfur compound that contributes little to the atmospheric sulfur flux. The activity of these pathways control the natural flux of sulfur released to the atmosphere. Although these biochemical pathways and the factors that regulate them are of great interest, they are poorly understood. Only recently have some of the genes and pathways responsible for DMSP catabolism been elucidated. Thus far, six different enzymes have been identified that catalyze the cleavage of DMSP, resulting in the release of DMS. In addition, five of these enzymes appear to produce acrylate, while one produces 3-hydroxypropionate. In contrast, only one enzyme, designated DmdA, has been identified that catalyzes the demethylation reaction producing methylmercaptopropionate (MMPA). The metabolism of MMPA is performed by a series of three coenzyme-A mediated reactions catalyzed by DmdB, DmdC, and DmdD. Interestingly, Candidatus Pelagibacter ubique, a member of the SAR11 clade of Alphaproteobacteria that is highly abundant in marine surface waters, possessed functional DmdA, DmdB, and DmdC enzymes. Microbially mediated transformations of both DMS and methanethiol are also possible, although many of the biochemical and molecular genetic details are still unknown. This review will focus on the recent discoveries in the biochemical pathways that mineralize and assimilate DMSP carbon and sulfur, as well as the areas for which a comprehensive understanding is still lacking. PMID:21886640

  8. The Effects of Trimethylamine and Organic Matter Additions on the Stable Carbon Isotopic Composition of Methane Produced in Hypersaline Microbial Mat Environments

    NASA Astrophysics Data System (ADS)

    Kelley, C. A.; Nicholson, B. E.; Beaudoin, C. S.; Detweiler, A. M.; Bebout, B.

    2014-12-01

    Methane production has been observed in a number of hypersaline environments, and it is generally thought that this methane is produced through the use of non-competitive substrates, such as the methylamines, methanol and dimethylsulfide. The stable carbon isotopic composition of the produced methane has suggested that the methanogens are operating under conditions of substrate limitation. We investigated substrate limitation in gypsum-hosted endoevaporite and soft mat hypersaline environments by the additions of trimethylamine, a non-competitive substrate for methanogenesis, and dried microbial mat, a source of natural organic matter. The δ13C values of the methane produced after amendments were compared to those in unamended control vials. At all hypersaline sites investigated, the δ13C values of the methane produced in the amended vials were statistically lower (by 10 to 71 ‰) than the unamended controls, supporting the hypothesis of substrate limitation at these sites. When substrates were added to the incubation vials, the methanogens within the vials fractionated carbon isotopes to a greater degree, resulting in the production of more 13C-depleted methane. Trimethylamine-amended samples produced lower methane δ13C values than the mat-amended samples. This difference in the δ13C values between the two types of amendments could be due to differences in isotope fractionation associated with the dominant methane production pathway (or substrate used) within the vials, with trimethylamine being the main substrate used in the trimethylamine-amended vials. We hypothesize that increased natural organic matter in the mat-amended vials would increase fermentation rates, leading to higher H2 concentrations and increased CO2/H2 methanogenesis.

  9. Atmospheric Sulfur Cycle Simulated in The Global Model GOCART: Model Description and Global Properties

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Rood, Richard B.; Lin, Shian-Jiann; Mueller, Jean-Francois; Thompson, Anne M.

    2000-01-01

    The Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model is used to simulate the atmospheric sulfur cycle. The model uses the simulated meteorological data from the Goddard Earth Observing System Data Assimilation System (GEOS DAS). Global sulfur budgets from a 6-year simulation for SO2, sulfate, dimethylsulfide (DMS), and methanesulfonic acid (MSA) are presented in this paper. In a normal year without major volcanic perturbations, about 20% of the sulfate precursor emission is from natural sources (biogenic and volcanic) and 80% is anthropogenic: the same sources contribute 339% and 67% respectively to the total sulfate burden. A sulfate production efficiency of 0.41 - 0.42 is estimated in the model, an efficiency which is defined as a ratio of the amount oi sulfate produced to the total amount of SO2 emitted and produced in the atmosphere. This value indicates that less than half of the SO2 entering the atmosphere contributes to the sulfate production, the rest being removed by dry and wet depositions. In a simulation for 1990, we estimate a total sulfate production of 39 Tg S /yr with 36% and 64% respectively from in-air and in-cloud oxidation of SO2. We also demonstrate that major volcanic eruptions, such as the Mt. Pinatubo eruption in 1991, can significantly change the sulfate formation pathways, distributions, abundance, and lifetime. Comparison with other models shows that the parameterizations for wet removal or wet production of sulfate are the most critical factors in determining the burdens of SO2 and sulfate. Therefore, a priority for future research should be to reduce the large uncertainties associated with the wet physical and chemical processes.

  10. Plankton origin of particulate dimethylsulfoniopropionate in a Mediterranean oligotrophic coastal and shallow ecosystem

    NASA Astrophysics Data System (ADS)

    Jean, Natacha; Bogé, Gérard; Jamet, Jean-Louis; Jamet, Dominique; Richard, Simone

    2009-03-01

    We report here dimethylsulfide (DMS) and dimethylsulfoniopropionate (DMSP) levels as a function of plankton communities and abiotic factors over a 12-month cycle in the Mediterranean oligotrophic coastal and shallow ecosystem of Niel Bay (N.W. Mediterranean Sea, France). Total particulate DMSP (DMSP p) and DMS concentrations were highly seasonal, peaking during a spring (April) bloom at 8.9 nM and 73.9 nM, respectively. Significant positive correlations were found between total DMSP p concentration and the abundance or biomass of the dinoflagellate Prorocentrum compressum (Spearman's rank correlation test: r = 0.704; p = 0.011). Similarly, DMS concentrations peaked during the development of blooms of P. compressum and Gymnodinium sp. There seemed to be a positive relationship between the chlorophyll a to pheopigment ratio and DMS concentrations, suggesting that DMS was released during phytoplankton growth. High DMS levels recorded in the shallow Niel Bay may also result from the activity of benthic macroalgae, and/or macrophytes such as Posidonia spp., or the resuspension of sulfur species accumulating in sediments. The fractionation of particulate DMSP into three size classes (>90 μm, 5-90 μm and 0.2-5 μm) revealed that 5-90 μm DMSP-containing particles made the greatest contribution to the total DMSP p pool (annual mean contribution = 62%), with a maximal contribution in April (96%). This size class consisted mainly of dinoflagellates (annual mean contribution = 68%), with P. compressum and Gymnodinium sp. the predominant species, together accounting for up to 44% of the phytoplankton present. The positive correlation between DMSP concentration in the 5-90 μm size class and the abundance of P. compressum (Spearman's rank correlation test: r = 0.648; p = 0.023) suggests that this phytoplankton species would be the major DMSP producer in Niel Bay. The DMSP collected in the >90 μm fraction was principally associated with zooplankton organisms, dominated by

  11. Molecular analysis of volatile metabolites released specifically by staphylococcus aureus and pseudomonas aeruginosa

    PubMed Central

    2012-01-01

    Background The routinely used microbiological diagnosis of ventilator associated pneumonia (VAP) is time consuming and often requires invasive methods for collection of human specimens (e.g. bronchoscopy). Therefore, it is of utmost interest to develop a non-invasive method for the early detection of bacterial infection in ventilated patients, preferably allowing the identification of the specific pathogens. The present work is an attempt to identify pathogen-derived volatile biomarkers in breath that can be used for early and non- invasive diagnosis of ventilator associated pneumonia (VAP). For this purpose, in vitro experiments with bacteria most frequently found in VAP patients, i.e. Staphylococcus aureus and Pseudomonas aeruginosa, were performed to investigate the release or consumption of volatile organic compounds (VOCs). Results Headspace samples were collected and preconcentrated on multibed sorption tubes at different time points and subsequently analyzed with gas chromatography mass spectrometry (GC-MS). As many as 32 and 37 volatile metabolites were released by S. aureus and P. aeruginosa, respectively. Distinct differences in the bacteria-specific VOC profiles were found, especially with regard to aldehydes (e.g. acetaldehyde, 3-methylbutanal), which were taken up only by P. aeruginosa but released by S. aureus. Differences in concentration profiles were also found for acids (e.g. isovaleric acid), ketones (e.g. acetoin, 2-nonanone), hydrocarbons (e.g. 2-butene, 1,10-undecadiene), alcohols (e.g. 2-methyl-1-propanol, 2-butanol), esters (e.g. ethyl formate, methyl 2-methylbutyrate), volatile sulfur compounds (VSCs, e.g. dimethylsulfide) and volatile nitrogen compounds (VNCs, e.g. 3-methylpyrrole). Importantly, a significant VOC release was found already 1.5 hours after culture start, corresponding to cell numbers of ~8*106 [CFUs/ml]. Conclusions The results obtained provide strong evidence that the detection and perhaps even identification of bacteria

  12. BIOSIGNATURE GASES IN H{sub 2}-DOMINATED ATMOSPHERES ON ROCKY EXOPLANETS

    SciTech Connect

    Seager, S.; Bains, W.; Hu, R.

    2013-11-10

    Super-Earth exoplanets are being discovered with increasing frequency and some will be able to retain stable H{sub 2}-dominated atmospheres. We study biosignature gases on exoplanets with thin H{sub 2} atmospheres and habitable surface temperatures, using a model atmosphere with photochemistry and a biomass estimate framework for evaluating the plausibility of a range of biosignature gas candidates. We find that photochemically produced H atoms are the most abundant reactive species in H{sub 2} atmospheres. In atmospheres with high CO{sub 2} levels, atomic O is the major destructive species for some molecules. In Sun-Earth-like UV radiation environments, H (and in some cases O) will rapidly destroy nearly all biosignature gases of interest. The lower UV fluxes from UV-quiet M stars would produce a lower concentration of H (or O) for the same scenario, enabling some biosignature gases to accumulate. The favorability of low-UV radiation environments to accumulate detectable biosignature gases in an H{sub 2} atmosphere is closely analogous to the case of oxidized atmospheres, where photochemically produced OH is the major destructive species. Most potential biosignature gases, such as dimethylsulfide and CH{sub 3}Cl, are therefore more favorable in low-UV, as compared with solar-like UV, environments. A few promising biosignature gas candidates, including NH{sub 3} and N{sub 2}O, are favorable even in solar-like UV environments, as these gases are destroyed directly by photolysis and not by H (or O). A more subtle finding is that most gases produced by life that are fully hydrogenated forms of an element, such as CH{sub 4} and H{sub 2}S, are not effective signs of life in an H{sub 2}-rich atmosphere because the dominant atmospheric chemistry will generate such gases abiologically, through photochemistry or geochemistry. Suitable biosignature gases in H{sub 2}-rich atmospheres for super-Earth exoplanets transiting M stars could potentially be detected in transmission

  13. Potential for a biogenic influence on cloud microphysics over the ocean: a correlation study with satellite-derived data

    NASA Astrophysics Data System (ADS)

    Lana, A.; Simó, R.; Vallina, S. M.; Dachs, J.

    2012-09-01

    Aerosols have a large potential to influence climate through their effects on the microphysics and optical properties of clouds and, hence, on the Earth's radiation budget. Aerosol-cloud interactions have been intensively studied in polluted air, but the possibility that the marine biosphere plays an important role in regulating cloud brightness in the pristine oceanic atmosphere remains largely unexplored. We used 9 yr of global satellite data and ocean climatologies to derive parameterizations of the temporal variability of (a) production fluxes of sulfur aerosols formed by the oxidation of the biogenic gas dimethylsulfide emitted from the sea surface; (b) production fluxes of secondary organic aerosols from biogenic organic volatiles; (c) emission fluxes of biogenic primary organic aerosols ejected by wind action on sea surface; and (d) emission fluxes of sea salt also lifted by the wind upon bubble bursting. Series of global monthly estimates of these fluxes were correlated to series of potential cloud condensation nuclei (CCN) numbers derived from satellite (MODIS). More detailed comparisons among weekly series of estimated fluxes and satellite-derived cloud droplet effective radius (re) data were conducted at locations spread among polluted and clean regions of the oceanic atmosphere. The outcome of the statistical analysis was that positive correlation to CCN numbers and negative correlation to re were common at mid and high latitude for sulfur and organic secondary aerosols, indicating both might be important in seeding cloud droplet activation. Conversely, primary aerosols (organic and sea salt) showed widespread positive correlations to CCN only at low latitudes. Correlations to re were more variable, non-significant or positive, suggesting that, despite contributing to large shares of the marine aerosol mass, primary aerosols are not widespread major drivers of the variability of cloud microphysics. Validation against ground measurements pointed out that

  14. Phytoplankton bloom dynamics in coastal ecosystems: A review with some general lessons from sustained investigation of San Francisco Bay, California

    USGS Publications Warehouse

    Cloern, James E.

    1996-01-01

    Phytoplankton blooms are prominent features of biological variability in shallow coastal ecosystems such as estuaries, lagoons, bays, and tidal rivers. Long-term observation and research in San Francisco Bay illustrates some patterns of phytoplankton spatial and temporal variability and the underlying mechanisms of this variability. Blooms are events of rapid production and accumulation of phytoplankton biomass that are usually responses to changing physical forcings originating in the coastal ocean (e.g., tides), the atmosphere (wind), or on the land surface (precipitation and river runoff). These physical forcings have different timescales of variability, so algal blooms can be short-term episodic events, recurrent seasonal phenomena, or rare events associated with exceptional climatic or hydrologic conditions. The biogeochemical role of phytoplankton primary production is to transform and incorporate reactive inorganic elements into organic forms, and these transformations are rapid and lead to measurable geochemical change during blooms. Examples include the depletion of inorganic nutrients (N, P, Si), supersaturation of oxygen and removal of carbon dioxide, shifts in the isotopic composition of reactive elements (C, N), production of climatically active trace gases (methyl bromide, dimethylsulfide), changes in the chemical form and toxicity of trace metals (As, Cd, Ni, Zn), changes in the biochemical composition and reactivity of the suspended particulate matter, and synthesis of organic matter required for the reproduction and growth of heterotrophs, including bacteria, zooplankton, and benthic consumer animals. Some classes of phytoplankton play special roles in the cycling of elements or synthesis of specific organic molecules, but we have only rudimentary understanding of the forces that select for and promote blooms of these species. Mounting evidence suggests that the natural cycles of bloom variability are being altered on a global scale by human

  15. Analysis of small scale turbulent structures and the effect of spatial scales on gas transfer

    NASA Astrophysics Data System (ADS)

    Schnieders, Jana; Garbe, Christoph

    2014-05-01

    processes on interfacial transport and relate it to gas transfer. References [1] T. G. Bell, W. De Bruyn, S. D. Miller, B. Ward, K. Christensen, and E. S. Saltzman. Air-sea dimethylsulfide (DMS) gas transfer in the North Atlantic: evidence for limited interfacial gas exchange at high wind speed. Atmos. Chem. Phys. , 13:11073-11087, 2013. [2] J Schnieders, C. S. Garbe, W.L. Peirson, and C. J. Zappa. Analyzing the footprints of near surface aqueous turbulence - an image processing based approach. Journal of Geophysical Research-Oceans, 2013.

  16. Seasonal and interannual variabilities of coccolithophore blooms in the Bay of Biscay and the Celtic Sea observed from a 18-year time-series of non-algal Suspended Particulate Matter images

    NASA Astrophysics Data System (ADS)

    Perrot, Laurie; Gohin, Francis; Ruiz-Pino, Diana; Lampert, Luis

    2016-04-01

    Coccolithophores belong to the nano-phytoplankton size-class and produce CaCO3 scales called coccoliths which form the «shell» of the algae cell. Coccoliths are in the size range of a few μm and can also be detached from the cell in the water. This phytoplankton group has an ubiquitous distribution in all oceans but blooms only in some oceanic regions, like the North East Atlantic ocean and the South Western Atlantic (Patagonian Sea). At a global scale coccolithopore blooms are studied in regard of CaCO3 production and three potential feedback on climate change: albedo modification by the way of dimethylsulfide (DMS) production and atmospheric CO2 source by calcification and a CO2 pump by photosynthesis. As the oceans are more and more acidified by anthropogenic CO2 emissions, coccolithophores generally are expected to be negatively affected. However, recent studies have shown an increase in coccolithophore occurrence in the North Atlantic. A poleward expansion of the coccolithophore Emiliana Huxleyi has also been pointed out. By using a simplified fuzzy method applied to a 18-year time series of SeaWiFS (1998-2002) and MODIS (2003-2015) spectral reflectance, we assessed the seasonal and inter-annual variability of coccolithophore blooms in the vicinity of the shelf break in the Bay of Biscay and the Celtic Sea After identification of the coccolith pixels by applying the fuzzy method, the abundance of coccoliths is assessed from a database of non-algal Suspended Particulate Matter (SPM). Although a regular pattern in the phenology of the blooms is observed, starting south in April in Biscay and moving northwards until July in Ireland, there is a high seasonal and interannual variability in the extent of the blooms. Year 2014 shows very low concentrations of detached coccoliths (twice less than average) from space and anomalies point out the maximum level in 2001. Non-algal SPM, derived from a procedure defined for the continental shelf, appears to be well

  17. The effect of surface irradiance on the absorption spectrum of chromophoric dissolved organic matter in the global ocean

    NASA Astrophysics Data System (ADS)

    Swan, Chantal M.; Nelson, Norman B.; Siegel, David A.; Kostadinov, Tihomir S.

    2012-05-01

    The cycling pathways of chromophoric dissolved organic matter (CDOM) within marine systems must be constrained to better assess the impact of CDOM on surface ocean photochemistry and remote sensing of ocean color. Photobleaching, the loss of absorption by CDOM due to light exposure, is the primary sink for marine CDOM. Herein the susceptibility of CDOM to photobleaching by sea surface-level solar radiation was examined in 15 samples collected from wide-ranging open ocean regimes. Samples from the Pacific, Atlantic, Indian and Southern Oceans were irradiated over several days with full-spectrum light under a solar simulator at in situ temperature in order to measure photobleaching rate and derive an empirical matrix, ɛsurf (m-1 μEin-1), which quantifies the effect of surface irradiance on the spectral absorption of CDOM. Irradiation responses among the ocean samples were similar within the ultraviolet (UV) region of the spectrum spanning 300-360 nm, generally exhibiting a decrease in the CDOM absorption coefficient (m-1) and concomitant increase in the CDOM spectral slope parameter, S (nm-1). However, an unexpected irradiation-induced increase in CDOM absorption between approximately 360 and 500 nm was observed for samples from high-nutrient low-chlorophyll (HNLC) environments. This finding was linked to the presence of dissolved nitrate and may explain discrepancies in action spectra for dimethylsulfide (DMS) photobleaching observed between the Equatorial Pacific and Subtropical North Atlantic Oceans. The nitrate-to-phosphate ratio explained 27-70% of observed variability in ɛsurf at observation wavelengths of 330-440 nm, while the initial spectral slope of the samples explained up to 52% of variability in ɛsurf at observation wavelengths of 310-330 nm. These results suggest that the biogeochemical and solar exposure history of the water column, each of which influence the chemical character and thus the spectral quality of CDOM and its photoreactivity, are the

  18. Modelling marine emissions and atmospheric distributions of halocarbons and DMS: the influence of prescribed water concentration vs. prescribed emissions

    NASA Astrophysics Data System (ADS)

    Lennartz, S. T.; Krysztofiak-Tong, G.; Marandino, C. A.; Sinnhuber, B.-M.; Tegtmeier, S.; Ziska, F.; Hossaini, R.; Krüger, K.; Montzka, S. A.; Atlas, E.; Oram, D.; Keber, T.; Bönisch, H.; Quack, B.

    2015-06-01

    Marine produced short-lived trace gases such as dibromomethane (CH2Br2), bromoform (CHBr3), methyliodide (CH3I) and dimethylsulfide (DMS) significantly impact tropospheric and stratospheric chemistry. Describing their marine emissions in atmospheric chemistry models as accurately as possible is necessary to quantify their impact on ozone depletion and the Earth's radiative budget. So far, marine emissions of trace gases have mainly been prescribed from emission climatologies, thus lacking the interaction between the actual state of the atmosphere and the ocean. Here we present simulations with the chemistry climate model EMAC with online calculation of emissions based on surface water concentrations, in contrast to directly prescribed emissions. Considering the actual state of the model atmosphere results in a concentration gradient consistent with model real-time conditions at ocean surface and atmosphere, which determine the direction and magnitude of the computed flux. This method has a number of conceptual and practical benefits, as the modelled emission can respond consistently to changes in sea surface temperature, surface wind speed, sea ice cover and especially atmospheric mixing ratio. This online calculation could enhance, dampen or even invert the fluxes (i.e. deposition instead of emissions) of VSLS. We show that differences between prescribing emissions and prescribing concentrations (-28 % for CH2Br2 to +11 % for CHBr3) result mainly from consideration of the actual, time-varying state of the atmosphere. The absolute magnitude of the differences depends mainly on the surface ocean saturation of each particular gas. Comparison to observations from aircraft, ships and ground stations reveals that computing the air-sea flux interactively leads in most of the cases to more accurate atmospheric mixing ratios in the model compared to the computation from prescribed emissions. Calculating emissions online also enables effective testing of different air

  19. Theoretical spectroscopic characterization at low temperatures of detectable sulfur-organic compounds: ethyl mercaptan and dimethyl sulfide.

    PubMed

    Senent, M L; Puzzarini, C; Domínguez-Gómez, R; Carvajal, M; Hochlaf, M

    2014-03-28

    Highly correlated ab initio methods are used for the spectroscopic characterization of ethyl mercaptan (CH3CH2 (32)SH, ETSH) and dimethyl sulfide (CH3 (32)SCH3, DMS), considering them on the vibrational ground and excited torsional states. Since both molecules show non-rigid properties, torsional energy barriers and splittings are provided. Equilibrium geometries and the corresponding rotational constants are calculated by means of a composite scheme based on CCSD(T) calculations that accounts for the extrapolation to the complete basis set limit and core-correlation effects. The ground and excited states rotational constants are then determined using vibrational corrections obtained from CCSD/cc-pVTZ force-field calculations, which are also employed to determine anharmonic frequencies for all vibrational modes. CCSD(T) and CCSD force fields are employed to predict quartic and sextic centrifugal-distortion constants, respectively. Equilibrium rotational constants are also calculated using CCSD(T)-F12. The full-dimensional anharmonic analysis does not predict displacements of the lowest torsional excited states due to Fermi resonances with the remaining vibrational modes. Thus, very accurate torsional transitions are calculated by solving variationally two-dimensional Hamiltonians depending on the CH3 and SH torsional coordinates of ethyl mercaptan or on the two methyl groups torsions of dimethyl-sulfide. For this purpose, vibrationally corrected potential energy surfaces are computed at the CCSD(T)/aug-cc-pVTZ level of theory. For ethyl mercaptan, calculations show large differences between the gauche (g) and trans (t) conformer spectral features. Interactions between rotating groups are responsible for the displacements of the g-bands with respect to the t-bands that cannot therefore be described with one-dimensional models. For DMS, the CCSD(T) potential energy surface has been semi-empirically adjusted to reproduce experimental data. New assignments are

  20. Theoretical spectroscopic characterization at low temperatures of detectable sulfur-organic compounds: ethyl mercaptan and dimethyl sulfide.

    PubMed

    Senent, M L; Puzzarini, C; Domínguez-Gómez, R; Carvajal, M; Hochlaf, M

    2014-03-28

    Highly correlated ab initio methods are used for the spectroscopic characterization of ethyl mercaptan (CH3CH2 (32)SH, ETSH) and dimethyl sulfide (CH3 (32)SCH3, DMS), considering them on the vibrational ground and excited torsional states. Since both molecules show non-rigid properties, torsional energy barriers and splittings are provided. Equilibrium geometries and the corresponding rotational constants are calculated by means of a composite scheme based on CCSD(T) calculations that accounts for the extrapolation to the complete basis set limit and core-correlation effects. The ground and excited states rotational constants are then determined using vibrational corrections obtained from CCSD/cc-pVTZ force-field calculations, which are also employed to determine anharmonic frequencies for all vibrational modes. CCSD(T) and CCSD force fields are employed to predict quartic and sextic centrifugal-distortion constants, respectively. Equilibrium rotational constants are also calculated using CCSD(T)-F12. The full-dimensional anharmonic analysis does not predict displacements of the lowest torsional excited states due to Fermi resonances with the remaining vibrational modes. Thus, very accurate torsional transitions are calculated by solving variationally two-dimensional Hamiltonians depending on the CH3 and SH torsional coordinates of ethyl mercaptan or on the two methyl groups torsions of dimethyl-sulfide. For this purpose, vibrationally corrected potential energy surfaces are computed at the CCSD(T)/aug-cc-pVTZ level of theory. For ethyl mercaptan, calculations show large differences between the gauche (g) and trans (t) conformer spectral features. Interactions between rotating groups are responsible for the displacements of the g-bands with respect to the t-bands that cannot therefore be described with one-dimensional models. For DMS, the CCSD(T) potential energy surface has been semi-empirically adjusted to reproduce experimental data. New assignments are

  1. Aerosol composition, chemistry, and source characterization during the 2008 VOCALS Experiment

    SciTech Connect

    Lee, Y.; Springston, S.; Jayne, J.; Wang, J.; Senum, G.; Hubbe, J.; Alexander, L.; Brioude, J.; Spak, S.; Mena-Carrasco, M.; Kleinman, L.; Daum, P.

    2010-03-15

    Chemical composition of fine aerosol particles over the northern Chilean coastal waters was determined onboard the U.S. DOE G-1 aircraft during the VOCALS (VAMOS Ocean-Cloud-Atmosphere-Land Study) field campaign between October 16 and November 15, 2008. SO42-, NO3-, NH4+, and total organics (Org) were determined using an Aerodyne Aerosol Mass Spectrometer, and SO42-, NO3-, NH4+, Na+, Cl-, CH3SO3-, Mg2+, Ca2+, and K+ were determined using a particle-into-liquid sampler-ion chromatography technique. The results show the marine boundary layer (MBL) aerosol mass was dominated by non- sea-salt SO42- followed by Na+, Cl-, Org, NO3-, and NH4+, in decreasing importance; CH3SO3-, Ca2+, and K+ rarely exceeded their respective limits of detection. The SO42- aerosols were strongly acidic as the equivalent NH4+ to SO42- ratio was only {approx}0.25 on average. NaCl particles, presumably of sea-salt origin, showed chloride deficits but retained Cl- typically more than half the equivalency of Na+, and are externally mixed with the acidic sulfate aerosols. Nitrate was observed only on sea-salt particles, consistent with adsorption of HNO3 on sea-salt aerosols, responsible for the Cl- deficit. Dust particles appeared to play a minor role, judging from the small volume differences between that derived from the observed mass concentrations and that calculated based on particle size distributions. Because SO42- concentrations were substantial ({approx}0.5 - {approx}3 {micro}g/m3) with a strong gradient (highest near the shore), and the ocean-emitted dimethylsulfide and its unique oxidation product, CH3SO3-, were very low (i.e., {le} 40 parts per trillion and <0.05 {micro}g/m3, respectively), the observed SO42- aerosols are believed to be primarily of terrestrial origin. Back trajectory calculations indicate sulfur emissions from smelters and power plants along coastal regions of Peru and Chile are the main sources of these SO4- aerosols. However, compared to observations, model

  2. Modal structure of chemical mass size distribution in the high Arctic aerosol

    NASA Astrophysics Data System (ADS)

    Hillamo, Risto; Kerminen, Veli-Matti; Aurela, Minna; MäKelä, Timo; Maenhaut, Willy; Leek, Caroline

    2001-11-01

    dimethylsulfide (DMS) emissions from biogenic processes in seawater, followed by gas-to-particle conversion, formation of particulate sulfate and methane sulfonate (MSA) and neutralization by ammonia.

  3. Potential aromatic compounds as markers to differentiate between Tuber melanosporum and Tuber indicum truffles.

    PubMed

    Culleré, Laura; Ferreira, Vicente; Venturini, María E; Marco, Pedro; Blanco, Domingo

    2013-11-01

    The Tuber indicum (Chinese truffle) and Tuber melanosporum (Black truffle) species are morphologically very similar but their aromas are very different. The black truffle aroma is much more intense and complex, and it is consequently appreciated more gastronomically. This work tries to determine whether the differences between the aromatic compounds of both species are sufficiently significant so as to apply them to fraud detection. An olfactometric evaluation (GC-O) of T. indicum was carried out for the first time. Eight important odorants were identified. In order of aromatic significance, these were: 1-octen-3-one and 1-octen-3-ol, followed by two ethyl esters (ethyl isobutyrate and ethyl 2-methylbutyrate), 3-methyl-1-butanol, isopropyl acetate, and finally the two sulfides dimethyldisulfide (DMDS) and dimethylsulfide (DMS). A comparison of this aromatic profile with that of T. melanosporum revealed the following differences: T. indicum stood out for the significant aromatic contribution of 1-octen-3-one and 1-octen-3-ol (with modified frequencies (MF%) of 82% and 69%, respectively), while in the case of T. melanosporum both had modified frequencies of less than 30%. Ethyl isobutyrate, ethyl 2-methylbutyrate and isopropyl acetate were also significantly higher, while DMS and DMDS had low MF (30-40%) compared to T. melanosporum (>70%). The volatile profiles of both species were also studied by means of headspace solid-phase microextraction (HS-SPME-GC-MS). This showed that the family of C8 compounds (3-octanone, octanal, 1-octen-3-one, 3-octanol and 1-octen-3-ol) is present in T. indicum at much higher levels. The presence of 1-octen-3-ol was higher by a factor of about 100, while 1-octen-3-one was detected in T. indicum only (there was no chromatographic signal in T. melanosporum). As well as showing the greatest chromatographic differences, these two compounds were also the most powerful from the aromatic viewpoint in the T. indicum olfactometry. Therefore

  4. Pollution Levels in Fog at the Chilean Coast

    NASA Astrophysics Data System (ADS)

    Sträter, E.; Klemm, O.; Westbeld, A.

    2010-07-01

    oceanic dimethylsulfide (DMS). With regard to the back trajectories, the air masses generally reach the study site from southerly directions after travelling along the Chilean coast. Presumably the air masses pick up pollutants in the densely populated cities, industrial plants and power plants along the Chilean coast and transport them over hundreds of kilometers to Patache. Here, they were detected as ingredients in fog water and lead to high pollution levels therein.

  5. Volatile Organic Compound (VOC) Emissions from Dairy Cows and Their Waste

    NASA Astrophysics Data System (ADS)

    Shaw, S.; Holzinger, R.; Mitloehner, F.; Goldstein, A.

    2005-12-01

    Biogenic VOCs are typically defined as those directly emitted from plants, but approximately 6% of global net primary production is consumed by cattle that carry out enteric fermentation and then emit VOCs that could also be considered biogenic. Current regulatory estimates suggest that dairy cattle in central California emit VOCs at rates comparable to those from passenger vehicles in the region, and thus contribute significantly to the extreme non-attainment of ozone standards there. We report PTR-MS measurements of ammonia and VOCs, and cavity-enhanced-absorption gas analyzer (Los Gatos Research, Inc.) measurements of CH4, emitted from dairy cattle in various stages of pregnancy/lactation and their waste. Experiments were conducted in chambers at UC Davis that simulate freestall cow housing conditions. CH4 fluxes ranged from 125-374 lb/cow/year. The compounds with the highest fluxes from '3 cows+waste' treatments were: ammonia (1-18), methanol (0-2.3), acetone+propanal (0.2-0.7), dimethylsulfide (0-0.4), and mass 109 (likely ID = p-cresol; 0-0.3) in lb/cow/year. Mass 60 (likely ID = trimethylamine) and acetic acid were also abundant. There were 10s of additional compounds with detectable, but small, emissions. A few compounds that were likely emitted (i.e. ethanol, formaldehyde, and dimethylamine) were not quantified by the PTR-MS. The total flux for all measured organic gases (TOG = CH4 + PTR-MS VOCs(including acetone+propanal)) averaged 246±45 lb/cow/year for '3 cows+waste' treatments, and was dominated by methane (>98%). TOG flux for 'waste only' treatments averaged 1.1±0.1 lb/cow/year, and was instead dominated by VOC (>84%). The PTR-MS VOCs as a percent of TOG (0.6±0.2%) emitted from '3 cows+waste' treatments in chamber conditions was a factor of 10 smaller than that currently estimated by the California Air Resources Board. In addition, the ozone forming potentials of the most abundant VOCs are only about 10% those of typical combustion or plant

  6. Relationship between methanesulfonate (MS-) in atmospheric particulate and remotely sensed phytoplankton activity in oligo-mesotrophic central Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Becagli, S.; Lazzara, L.; Fani, F.; Marchese, C.; Traversi, R.; Severi, M.; di Sarra, A.; Sferlazzo, D.; Piacentino, S.; Bommarito, C.; Dayan, U.; Udisti, R.

    2013-11-01

    The coupling between oceanic and atmospheric sulfur cycles is fundamental for the understanding of the role of sulfate particles as potential climate regulators. We discuss existing relationships among methanesulfonate (MS- - one of the end products of oxidation of biogenic dimethylsulfide - DMS) in the atmospheric particulate, phytoplankton biomass, and remotely-sensed activity in the central Mediterranean. The MS- concentration in the aerosol particles is based on PM10 sampling (from 2005 to 2008) of atmospheric aerosols at the island of Lampedusa (35.5°N, 12.6°E) in the central Mediterranean Sea. The marine primary production in the sea sector surrounding the sampling site is obtained by using Ocean Color remote sensed data (SeaWiFS, MODIS-Aqua). In particular, primary production is calculated using a bio-optical model of sea reflectance and a Wavelength-Depth-Resolved Model (WDRM), fed by elaborated satellite data (chlorophyll concentration in the euphotic layer - Chl, sea surface temperature) and daily solar surface irradiance measurements. The multi-year evolution of MS- atmospheric concentration shows a well-defined seasonal cycle with a summer maximum, corresponding to the annual peak of solar radiation and a minimum of phytoplankton biomass (expressed as Chl). Statistically significant linear relationships between monthly means of atmospheric MS- and both the phytoplankton productivity index PB (r2 = 0.84, p < 0.001) and the solar radiation dose (SRD; r2 = 0.87, p < 0.001) in the upper mixed layer of the sea around Lampedusa are found. These correlations are mainly driven by the common seasonal pattern and suggest that DMS production in the marine surface layer is mainly related to the phytoplankton physiology. High values of PB are also the expression of stressed cells. The main stress factors in Mediterranean Sea during summer are high irradiance and shallow depth of the upper mixed layer, which lead to enhanced DMS emissions and higher MS- amounts in

  7. Nature of the N-H...S hydrogen bond.

    PubMed

    Biswal, Himansu S; Wategaonkar, Sanjay

    2009-11-19

    The N-H...S hydrogen-bonded complexes of the model compounds of tryptophan (indole and 3-methylindole) and methionine (dimethyl sulfide, Me(2)S) have been characterized by a combination of experimental techniques like resonant two-photon ionization (R2PI), resonant ion dip infrared spectroscopy (RIDIRS), and fluorescence dip infrared spectroscopy (FDIRS) and computational methods like ab initio electronic structure calculations, atoms-in-molecules (AIM), natural bond orbital (NBO), and energy decomposition analyses. The results are compared with the N-H...O (M.H(2)O; M = indole, 3-methyl indole) sigma-type and N-H...Phi (M.benzene) pi-type hydrogen-bonded complexes. It was shown that the S(1)-S(0) band origin red shifts in the N-H...S hydrogen-bonded complexes correlated well with the polarizability of the acceptor rather than their proton affinity, contrary to the trend observed in most X-H...Y (X, Y = O, N, halogens, etc.) hydrogen-bonded systems. The red shift in the N-H stretching frequency in the N-H...S HB clusters (Me(2)S as HB acceptor) was found to be 1.8 times greater than that for the N-H...O hydrogen-bonded complexes (H(2)O as HB acceptor), although the binding energies for the two complexes were comparable. The energy decomposition analyses for all of the N-H...S hydrogen-bonded complexes showed that the correlation (or dispersion) energy has significant contribution to the total binding energy. It is pointed out that the binding energy of the N-H...S complex was also comparable to that of the indole.benzene complex, which is completely dominated by the dispersion interaction. Atoms-in-molcules (AIM) and natural bond orbital (NBO) analyses indicated a nontrivial electrostatic component in the hydrogen-bonding interaction. Greater dispersion contribution to the stabilization energy as well as greater red shifts in the N-H stretch relative to those of N-H...O hydrogen-bonded complexes makes the indole.dimethylsulfide complex unique in regard to the

  8. WRF-Chem model predictions of the regional impacts of N2O5 heterogeneous processes on night-time chemistry over north-western Europe

    DOE PAGES

    Lowe, Douglas; Archer-Nicholls, Scott; Morgan, Will; Allan, James D.; Utembe, Steve; Ouyang, Bin; Aruffo, Eleonora; Le Breton, Michael; Zaveri, Rahul A.; di Carlo, Piero; et al

    2015-02-09

    alkenes (× 80) and comparable for dimethylsulfide (DMS). However the suppression of NO3 mixing ratios across the domain by N2O5 heterogeneous chemistry has only a very slight, negative, influence on this oxidative capacity. The influence on regional particulate nitrate mass loadings is stronger. Night-time N2O5 heterogeneous chemistry maintains the production of particulate nitrate within polluted regions: when this process is taken into consideration, the daytime peak (for the 95th percentile) of PM10 nitrate mass loadings remains around 5.6 μg kg−1air, but the night-time minimum increases from 3.5 to 4.6 μg kg−1air. The sustaining of higher particulate mass loadings through the night by this process improves model skill at matching measured aerosol nitrate diurnal cycles and will negatively impact on regional air quality, requiring this process to be included in regional models.« less

  9. Biogeochemistry of DMS in Surface Waters

    NASA Technical Reports Server (NTRS)

    Dacey, J. W. H.

    1997-01-01

    Dimethylsulfide (DMS) is important in influencing the formation of aerosols in the troposphere over large areas of the world's oceans. Understanding the dynamics of aerosols is important to understanding the earth's radiation balance. In evaluating the factors controlling DMS in the troposphere it is vital to understand the dynamics of DMS in the surface ocean. The biogeochemical processes controlling DMS concentration in seawater are myriad; modeling and theoretical estimation are problematic. At the beginning of this project we believed that we were on the verge of simplifying the ship-track measurement of DMS, and we proposed to deploy such a system to develop a database relating high frequency DMS measurements to biological and physicochemical and optical properties of surface water that can be quantified by remote sensing techniques. We designed a system to measure DMS concomitantly with other basic chemical and biological data in a flow-through system. The project was collaborative between Woods Hole Oceanographic Institution (WHOI) and Bermuda Biological Station for Research (BBSR). The project on which we are reporting was budgeted for only one year with a one year no-cost extension. At WHOI our effort was directed towards designing traps which would be used to concentrate DMS from seawater and allow storage for subsequent analysis. At that time, GC systems were too large for easy long-term deployment on a research vessel like R/V Weatherbird, so we focused on simplifying the shipboard sampling procedure. Initial studies of sample recovery with high levels of DMS suggested that Carboxen 1000, a relatively new carbon molecular sieve, could be used as a stable storage medium. The affinity of Carboxen for DMS is several orders of magnitude higher than gold wool (another adsorbent used for DMS collection) on a weight or volume basis. Furthermore, Carboxen's affinity for DMS is also far less susceptible to humidity than gold wool. Unfortunately, further

  10. Relationships linking primary production, sea ice melting, and biogenic aerosol in the Arctic

    NASA Astrophysics Data System (ADS)

    Becagli, S.; Lazzara, L.; Marchese, C.; Dayan, U.; Ascanius, S. E.; Cacciani, M.; Caiazzo, L.; Di Biagio, C.; Di Iorio, T.; di Sarra, A.; Eriksen, P.; Fani, F.; Giardi, F.; Meloni, D.; Muscari, G.; Pace, G.; Severi, M.; Traversi, R.; Udisti, R.

    2016-07-01

    This study examines the relationships linking methanesulfonic acid (MSA, arising from the atmospheric oxidation of the biogenic dimethylsulfide, DMS) in atmospheric aerosol, satellite-derived chlorophyll a (Chl-a), and oceanic primary production (PP), also as a function of sea ice melting (SIM) and extension of the ice free area in the marginal ice zone (IF-MIZ) in the Arctic. MSA was determined in PM10 samples collected over the period 2010-2012 at two Arctic sites, Ny Ålesund (78.9°N, 11.9°E), Svalbard islands, and Thule Air Base (76.5°N, 68.8°W), Greenland. PP is calculated by means of a bio-optical, physiologically based, semi-analytical model in the potential source areas located in the surrounding oceanic regions (Barents and Greenland Seas for Ny Ålesund, and Baffin Bay for Thule). Chl-a peaks in May in the Barents sea and in the Baffin Bay, and has maxima in June in the Greenland sea; PP follows the same seasonal pattern of Chl-a, although the differences in absolute values of PP in the three seas during the blooms are less marked than for Chl-a. MSA shows a better correlation with PP than with Chl-a, besides, the source intensity (expressed by PP) is able to explain more than 30% of the MSA variability at the two sites; the other factors explaining the MSA variability are taxonomic differences in the phytoplanktonic assemblages, and transport processes from the DMS source areas to the sampling sites. The taxonomic differences are also evident from the slopes of the correlation plots between MSA and PP: similar slopes (in the range 34.2-36.2 ng m-3of MSA/(gC m-2 d-1)) are found for the correlation between MSA at Ny Ålesund and PP in Barents Sea, and between MSA at Thule and PP in the Baffin Bay; conversely, the slope of the correlation between MSA at Ny Ålesund and PP in the Greenland Sea in summer is smaller (16.7 ng m-3of MSA/(gC m-2 d-1)). This is due to the fact that DMS emission from the Barents Sea and Baffin Bay is mainly related to the MIZ

  11. Oceanic isoprene and DMS distributions during low-productive conditions in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Booge, Dennis; Zavarsky, Alexander; Bell, Thomas; Marandino, Christa

    2015-04-01

    Despite their low abundances compared to the long lived greenhouse gases such as carbon dioxide and methane, short-lived trace gases produced in the oceans have been recognized as playing an important role in atmospheric chemistry and climate. Both isoprene and dimethylsulfide (DMS) are biogenic trace gases produced in the ocean and due to their supersaturation in the surface ocean are emitted to the atmosphere. Once emitted, they produce secondary organic aerosols via fast oxidation processes in the atmosphere (isoprene has a lifetime on approximately 1 hour and DMS 1 day). Consequently, both are hypothesized to significantly impact the radiative balance of the marine atmosphere. However, the strength of this impact is controversial. It is known that the emissions of these compounds to the atmosphere are critically controlled by surface ocean biogeochemical and physical factors which are, especially for isoprene, poorly quantified and unpredictable. Therefore, in order to more fully understand the role of isoprene and DMS on the marine atmosphere, more studies of their distributions, controlling factors, and air-sea exchange are urgently needed. Here we present preliminary measurements of isoprene and DMS concentrations from the SPACES and OASIS campaigns onboard the R/V Sonne that took place from July 8th to August 7th starting in Durban, South Africa and ending in Malé, Maledives. An improved purge and trap technique coupled with a gas chromatograph-mass spectrometer (GC-MS) was used to measure isoprene and DMS in one run for both surface and depth profile samples. In addition, an atmospheric pressure chemical ionization mass spectrometer (AP-CIMS) was used to perform continuous surface measurements of these compounds. The discrete surface measurements were made every three hours using a submersible pump located in the ship's moonpool at 6 m depth. For depth profile measurements samples were taken from 5 m to about 100 m depth. There have been no reported

  12. Investigations of Methane Production in Hypersaline Environments

    NASA Technical Reports Server (NTRS)

    Bebout, Brad M.

    2015-01-01

    produced by these sediments. Substrate limitation of methanogenesis in these environments, and not methane oxidation, would explain the isotopic values of the methane in these environments. Incubations with both isotopically labeled and unlabeled putative substrates for methanogenesis have shown that the substrates most important for methanogenesis in these environments are the so-called non-competitive substrates, e.g., methylamines, dimethylsulfide, and methanol. Acetate and bicarbonate appear not to be important substrates for methanogens in these environments. Extraction of DNA and analysis of a gene used for methane production (mcrA) has revealed that the community composition of methanogens is consistent with organisms known to use non-competitive substrates. Our work has shown that hypersaline environments have the potential to both produce and preserve methane for analysis, e.g., by capable rovers. Our work expends the range of methane isotopic values now known to be produced by active methanogenesis

  13. WRF-Chem model predictions of the regional impacts of N2O5 heterogeneous processes on night-time chemistry over north-western Europe

    SciTech Connect

    Lowe, Douglas; Archer-Nicholls, Scott; Morgan, Will; Allan, James D.; Utembe, Steve; Ouyang, Bin; Aruffo, Eleonora; Le Breton, Michael; Zaveri, Rahul A.; di Carlo, Piero; Percival, Carl; Coe, H.; Jones, Roderic L.; McFiggans, Gordon

    2015-02-09

    3 oxidation of VOCs across the whole region was found to be 100–300 times slower than the daytime OH oxidation of these compounds. The difference in contribution was less for alkenes (× 80) and comparable for dimethylsulfide (DMS). However the suppression of NO3 mixing ratios across the domain by N2O5 heterogeneous chemistry has only a very slight, negative, influence on this oxidative capacity. The influence on regional particulate nitrate mass loadings is stronger. Night-time N2O5 heterogeneous chemistry maintains the production of particulate nitrate within polluted regions: when this process is taken into consideration, the daytime peak (for the 95th percentile) of PM10 nitrate mass loadings remains around 5.6 μg kg−1air, but the night-time minimum increases from 3.5 to 4.6 μg kg−1air. The sustaining of higher particulate mass loadings through the night by this process improves model skill at matching measured aerosol nitrate diurnal cycles and will negatively impact on regional air quality, requiring this process to be included in regional models.

  14. Interactive effects of solar UV radiation and climate change on biogeochemical cycling.

    PubMed

    Zepp, R G; Erickson, D J; Paul, N D; Sulzberger, B

    2007-03-01

    exposure to increased UV-B radiation, and have synergistic effects on the penetration of light into aquatic ecosystems. Future changes in climate will enhance stratification of lakes and the ocean, which will intensify photodegradation of CDOM by UV radiation. The resultant increase in the transparency of water bodies may increase UV-B effects on aquatic biogeochemistry in the surface layer. Changing solar UV radiation and climate also interact to influence exchanges of trace gases, such as halocarbons (e.g., methyl bromide) which influence ozone depletion, and sulfur gases (e.g., dimethylsulfide) that oxidize to produce sulfate aerosols that cool the marine atmosphere. UV radiation affects the biological availability of iron, copper and other trace metals in aquatic environments thus potentially affecting metal toxicity and the growth of phytoplankton and other microorganisms that are involved in carbon and nitrogen cycling. Future changes in ecosystem distribution due to alterations in the physical and chemical climate interact with ozone-modulated changes in UV-B radiation. These interactions between the effects of climate change and UV-B radiation on biogeochemical cycles in terrestrial and aquatic systems may partially offset the beneficial effects of an ozone recovery. PMID:17344963

  15. WRF-Chem model predictions of the regional impacts of N2O5 heterogeneous processes on night-time chemistry over north-western Europe

    NASA Astrophysics Data System (ADS)

    Lowe, D.; Archer-Nicholls, S.; Morgan, W.; Allan, J.; Utembe, S.; Ouyang, B.; Aruffo, E.; Le Breton, M.; Zaveri, R. A.; Di Carlo, P.; Percival, C.; Coe, H.; Jones, R.; McFiggans, G.

    2015-02-01

    comparable for dimethylsulfide (DMS). However the suppression of NO3 mixing ratios across the domain by N2O5 heterogeneous chemistry has only a very slight, negative, influence on this oxidative capacity. The influence on regional particulate nitrate mass loadings is stronger. Night-time N2O5 heterogeneous chemistry maintains the production of particulate nitrate within polluted regions: when this process is taken into consideration, the daytime peak (for the 95th percentile) of PM10 nitrate mass loadings remains around 5.6 μg kg-1air, but the night-time minimum increases from 3.5 to 4.6 μg kg-1air. The sustaining of higher particulate mass loadings through the night by this process improves model skill at matching measured aerosol nitrate diurnal cycles and will negatively impact on regional air quality, requiring this process to be included in regional models.

  16. Effect of ocean acidification and elevated fCO2 on trace gas production by a Baltic Sea summer phytoplankton community

    NASA Astrophysics Data System (ADS)

    Webb, Alison L.; Leedham-Elvidge, Emma; Hughes, Claire; Hopkins, Frances E.; Malin, Gill; Bach, Lennart T.; Schulz, Kai; Crawfurd, Kate; Brussaard, Corina P. D.; Stuhr, Annegret; Riebesell, Ulf; Liss, Peter S.

    2016-08-01

    The Baltic Sea is a unique environment as the largest body of brackish water in the world. Acidification of the surface oceans due to absorption of anthropogenic CO2 emissions is an additional stressor facing the pelagic community of the already challenging Baltic Sea. To investigate its impact on trace gas biogeochemistry, a large-scale mesocosm experiment was performed off Tvärminne Research Station, Finland, in summer 2012. During the second half of the experiment, dimethylsulfide (DMS) concentrations in the highest-fCO2 mesocosms (1075-1333 µatm) were 34 % lower than at ambient CO2 (350 µatm). However, the net production (as measured by concentration change) of seven halocarbons analysed was not significantly affected by even the highest CO2 levels after 5 weeks' exposure. Methyl iodide (CH3I) and diiodomethane (CH2I2) showed 15 and 57 % increases in mean mesocosm concentration (3.8 ± 0.6 increasing to 4.3 ± 0.4 pmol L-1 and 87.4 ± 14.9 increasing to 134.4 ± 24.1 pmol L-1 respectively) during Phase II of the experiment, which were unrelated to CO2 and corresponded to 30 % lower Chl a concentrations compared to Phase I. No other iodocarbons increased or showed a peak, with mean chloroiodomethane (CH2ClI) concentrations measured at 5.3 (±0.9) pmol L-1 and iodoethane (C2H5I) at 0.5 (±0.1) pmol L-1. Of the concentrations of bromoform (CHBr3; mean 88.1 ± 13.2 pmol L-1), dibromomethane (CH2Br2; mean 5.3 ± 0.8 pmol L-1), and dibromochloromethane (CHBr2Cl, mean 3.0 ± 0.5 pmol L-1), only CH2Br2 showed a decrease of 17 % between Phases I and II, with CHBr3 and CHBr2Cl showing similar mean concentrations in both phases. Outside the mesocosms, an upwelling event was responsible for bringing colder, high-CO2, low-pH water to the surface starting on day t16 of the experiment; this variable CO2 system with frequent upwelling events implies that the community of the Baltic Sea is acclimated to regular significant declines in pH caused by up to 800 µatm fCO2. After

  17. Interactive effects of solar UV radiation and climate change on biogeochemical cycling.

    PubMed

    Zepp, R G; Erickson, D J; Paul, N D; Sulzberger, B

    2007-03-01

    exposure to increased UV-B radiation, and have synergistic effects on the penetration of light into aquatic ecosystems. Future changes in climate will enhance stratification of lakes and the ocean, which will intensify photodegradation of CDOM by UV radiation. The resultant increase in the transparency of water bodies may increase UV-B effects on aquatic biogeochemistry in the surface layer. Changing solar UV radiation and climate also interact to influence exchanges of trace gases, such as halocarbons (e.g., methyl bromide) which influence ozone depletion, and sulfur gases (e.g., dimethylsulfide) that oxidize to produce sulfate aerosols that cool the marine atmosphere. UV radiation affects the biological availability of iron, copper and other trace metals in aquatic environments thus potentially affecting metal toxicity and the growth of phytoplankton and other microorganisms that are involved in carbon and nitrogen cycling. Future changes in ecosystem distribution due to alterations in the physical and chemical climate interact with ozone-modulated changes in UV-B radiation. These interactions between the effects of climate change and UV-B radiation on biogeochemical cycles in terrestrial and aquatic systems may partially offset the beneficial effects of an ozone recovery.

  18. Methanogenesis in hypersaline environments -Analogs for Ancient Mars?

    NASA Astrophysics Data System (ADS)

    Bebout, Brad; Chanton, Jeff; Kelley, Cheryl; Tazaz, Amanda; Poole, Jennifer; García Maldonado, José Q.; López Cortés, Alejandro

    values, (ca. -60 to -30 o/oo). The hydrogen isotopic (δ 2 H) composition of the methane ranged from -450 to -350 o/oo. These combinations of carbon and hydrogen isotopic values include many outside of the range of values normally considered to be biogenic. Incubations of evaporitic minerals and sediments confirm, however, that the methane is indeed being produced within these sediments. Substrate limitation of methanogenesis in these environments, and not methane oxidation, can explain the isotopic values of the methane in these environments. Incubations with both isotopically labeled and unlabeled putative substrates for methanogenesis have shown that the substrates most important for methanogenesis in these environments are the so-called non competitive substrates, e.g., methylamines, dimethylsulfide, and methanol. Acetate and bicarbonate appear not to be important substrates for methanogens in these environments. Analysis of partial sequences of the methyl-CoM-reductase A gene (mcrA), involved in methane production, has revealed that the community composition of methanogens is consistent with organisms known to use non-competitive substrates. Our work has shown that hypersaline environments have the potential to both produce and preserve methane for analysis on other planets, e.g., by capable rovers on Mars. These studies expand the range of isotopic values now known to be produced by active methanogenesis, and offer explanations as to how methane with these particular stable isotopic values is produced.

  19. Water Soluble Organic Compounds over the Eastern Mediterranean: Study of their occurrence and sources

    NASA Astrophysics Data System (ADS)

    Tziaras, T.; Spyros, A.; Mandalakis, M.; Apostolaki, M.; Stephanou, E. G.

    2010-05-01

    Fine marine aerosols influence the climate system by acting as cloud condensation nuclei (CCN) in the atmosphere. The organic chemical composition and origin of the marine fine particulate matter are still largely unknown, because of the insufficient reports on in situ studies, the large variability in the emission from the sea, from the complex transfer of gases and particles at the air-sea interface, and the transport of aerosol particles from very distant sources. As important processes of formation of marine organic aerosol production we consider: transport of terrestrial particles, secondary organic aerosol (SOA) formation from the oxidation of biogenic dimethyl-sulfide (DMS), and biogenic particle emissions through sea spray. Specific compounds related to the above-mentioned processes have been proposed as molecular markers: e.g. n-alkanoic acids and n-alkanes (terrestrial particles), levoglucosan (biomass burning aerosol), aminoacids (biological terrestrial or marine particles), methanesulphonate (MSA) (DMS oxidation), C8 and C9 dicarboxylic acids and oxo-carboxylic acids (marine SOA) and other short-chain dicarboxylic acids (marine or terrestrial SOA), and humic-like compounds (emission of marine organic carbon). In our study, we made an effort to characterize the water-soluble organic fraction of marine aerosols collected at a background sampling site of Eastern Mediterranean (Finokalia, N35o20', E25o40', Island of Crete, Greece). The sampling period was 2007-2008. In order to identify and quantify the water-soluble organic compounds of marine aerosols determined in the present study we have used gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and nuclear magnetic resonance spectroscopy (NMR) and ion chromatography (IC). The origin of air masses arriving in the study area was studied by using backward trajectories calculation (NOAA HYSPLIT Model). In addition, we have used the "MODIS fire products" for fire

  20. Tropospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Buseck, P. R.; Schwartz, S. E.

    2003-12-01

    It is widely believed that "On a clear day you can see forever," as proclaimed in the 1965 Broadway musical of the same name. While an admittedly beautiful thought, we all know that this concept is only figurative. Aside from Earth's curvature and Rayleigh scattering by air molecules, aerosols - colloidal suspensions of solid or liquid particles in a gas - limit our vision. Even on the clearest day, there are billions of aerosol particles per cubic meter of air.Atmospheric aerosols are commonly referred to as smoke, dust, haze, and smog, terms that are loosely reflective of their origin and composition. Aerosol particles have arisen naturally for eons from sea spray, volcanic emissions, wind entrainment of mineral dust, wildfires, and gas-to-particle conversion of hydrocarbons from plants and dimethylsulfide from the oceans. However, over the industrial period, the natural background aerosol has been greatly augmented by anthropogenic contributions, i.e., those produced by human activities. One manifestation of this impact is reduced visibility (Figure 1). Thus, perhaps more than in other realms of geochemistry, when considering the composition of the troposphere one must consider the effects of these activities. The atmosphere has become a reservoir for vast quantities of anthropogenic emissions that exert important perturbations on it and on the planetary ecosystem in general. Consequently, much recent research focuses on the effects of human activities on the atmosphere and, through them, on the environment and Earth's climate. For these reasons consideration of the geochemistry of the atmosphere, and of atmospheric aerosols in particular, must include the effects of human activities. (201K)Figure 1. Impairment of visibility by aerosols. Photographs at Yosemite National Park, California, USA. (a) Low aerosol concentration (particulate matter of aerodynamic diameter less than 2.5 μm, PM2.5=0.3 μg m-3; particulate matter of aerodynamic diameter less than 10

  1. PERSPECTIVE: Snow matters in the polar regions

    NASA Astrophysics Data System (ADS)

    Sodeau, John

    2010-03-01

    Antarctica is not quite as chemically pristine as might sometimes be thought (Jones et al 2008). For example, as elsewhere, reduced sulfur species such as dimethylsulfide (DMS) are emitted from biogenic marine sources at the poles (Read et al 2008). Somewhat less well known is that inland (as opposed to coastal) field campaigns have also detected, within the Antarctic boundary layer (ABL), emissions containing unexpectedly high levels of diverse, oxidizing chemicals such as NOx, nitrate ions, formaldehyde, ozone and hydrogen peroxide (Honrath et al 1999, Hutterli et al 2004, Sumner and Shepson 1999). And then there are the halogen-containing compounds (Simpson et al 2007). The transformation of DMS to sulfate aerosols capable of acting as cloud condensation nuclei often proceeds via one main oxidized product of DMS, namely methanesulfonic acid (MSA). Two specific reactions have been well studied to date in this regard, namely DMS plus either OH or NO3 radicals. Corresponding reactions with halogen radicals, which also contribute to the oxidizing capacity of our atmosphere, have generally been considered to be of less importance. The reason for this view is that even though the reactivity of bromine- and iodine-containing radicals is much greater than that of OH, the halogens were thought to be relatively scarce in the polar atmosphere. However both BrO (and IO) have been detected in the Antarctic CHABLIS campaign, as discussed in depth in the Atmospheric Chemistry and Physics special issue of 2008, see Jones et al (2008). It was subsequently shown that calculated MSA production from the DMS/BrO reaction may be about an order of magnitude greater than when the OH radical was the oxidizing reactant. The recent analytical measurements by Antony et al (2010) of MSA, Br and NO3 found in snow along the Ingrid Christensen Coast of East Antarctica are important in the above field context. Hence it would appear that the concentrations of these ions in ice-cap sites are up