首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
Extensive ambient concentration and flux measurements have been performed in the heavily polluted region of Cubatão/Brazil. Substantial contribution of anthropogenic sources to the local reduced sulfur burden has been observed. As a result of this atmospheric sulfur burden average gas exchange between vegetated soils and the atmosphere shows net deposition. Based mainly on own field measurements a local budget for H2S, COS, and CS2 has been made up in order to calculate anthropogenic emissions. All major sources and sinks in the chosen atmospheric reservoir (24×20×1 km) have been taken into account. Due to the small reservoir size fluxes across its boundaries are dominant sources and sinks. The differences between outflux and influx therefore account for the unknown anthropogenic emissions which have been determined to be 80±10 (H2S), 66±15 (COS), and 29±6 Mmol year-1 (CS2). Other sources and sinks like natural emissions, chemical conversion, and dry deposition turned out to be of minor importance on a local scale. In fact, inside the investigated reservoir natural emissions were below 0.5% of anthropogenic emissions. Anthropogenic emissions of H2S, COS, and CS2 quantified in this work have been compared with global emission estimates for these compounds made by other authors. We conclude that global anthropogenic emissions of reduced sulfur compounds especially of COS and CS2 are currently under-estimated.  相似文献   

2.
Atmospheric concentrations of several reduced sulphur compounds (H2S, COS, CH3SH, CH3SCH3, CS2) originating from both natural and anthropogenic sources were measured at a number of locations in the All Saints Bay area and Reconcavo Baiano, Brazil.The volatile reduced sulphur compounds were collected by pre-concentration using cryo-tubes. Analysis of these compounds was carried out at a later date using gas chromatography with a flame photometric detector. In areas dominated by biogenic sources, the COS concentration varied between 0.5 and 1.0 ppbv, consistent with its normal global distribution in the atmosphere.Areas without direct industrial influence showed low atmospheric concentrations for all volatile sulphur compounds ( 0.25 ppbv).The anthropogenic influence of the Petrochemical Complex in Camaçari resulted in relatively high levels of some reduced sulphur compounds, such as COS (8 ppbv), CH3SH (1.50 ppbv), H2S (1.35 ppbv) and CS2 (0.3 ppbv). In mangrove areas, the H2S concentrations (0.2 ppbv) were almost twice as high as those in the air masses arriving from the Atlantic Ocean. The maximum H2S concentrations were found in the industrial area of the Petrochemical Complex in Camaçari, but did not reach the limit of human perception (0.14 ppbv) and rarely reached the typical recognizable smelling level (0.40 ppbv). Industrial emissions from the Landulfo Alves Refinery increased the COS, DMS and CS2 concentrations to 2.0, 0.55 and 0.2 ppbv, respectively.  相似文献   

3.
Investigations about VOSCs (volatile organic sulfur compounds) have been received increasing attention for their significant contribution to the nonvolcanic background sulfate layer in the stratosphere and the earth’s radiation balance and as a potential tool to understand the carbon budget. In this study, COS and CS2 were always recorded throughout the entire rice cultivation season of 2014. COS fluxes appeared as emission in non-planted soil and as uptake in planted soil, the corresponding results were obtained as 2.66 and ?2.35 pmol·m?2·s?1, respectively. For CS2, both planted and non-planted paddy fields acted as sources with an emission rate of 1.02 pmol·m?2·s?1 and 2.40 pmol·m?2·s?1, respectively. COS emission or uptake rates showed a distinct seasonal variation, with the highest fluxes at the jointing-booting stage. COS and CS2 fluxes increased with increasing N fertilizer use because of improved plant and microbial growth and activity. Plots treated with both N and S reduced COS and CS2 fluxes slightly compared with plots with only-N treatment. Light, soil moisture or temperature showed no significant correlation with COS and CS2 fluxes, but revealed the important impacts on the magnitude and direction of gases fluxes. The results also showed that the (available) sulfur contents in soil and roots had a certain effect on VOSCs emission or uptake. Our results highlight the significance of biotic and abiotic production and consumption processes existing in the soil.  相似文献   

4.
The net fluxes of carbonyl sulfide (COS) and carbon disulfide (CS2) to the atmosphere from nitrogen amended and unamended deciduous and coniferous forest soils were measured during the spring of 1986. We found that emissions of these gases from acidic forest soils were substantially increased after nitrogen fertilization. The total (COS+CS2) emissions were increased by nearly a factor of three in the hardwood stand and were more than doubled in the pine stand. Furthermore, vegetation type appeared to have an influence on which was the dominant sulfur gas released from the forest soils. The added nitrogen caused a dramatic increase in COS emissions from the hardwood stand (a factor of three increase), while CS2 emissions from this site were not affected. We observed the opposite response in the pine stand; that is, the nitrogen fertilization had no affect on COS emissions, but did stimulate CS2 emissions (a factor of more than nine increase).  相似文献   

5.
The diurnal-to-monthly behavior of the fluxes of OCS, H2S, and CS2 from a mixed-Spartina grass-covered site in a Wallops Island salt water marsh was determined through a series of experiments in August and September, 1982. Absolute flux values were determined for OCS and H2S, while only relative values were determined for CS2. The rates of emission of OCS and H2S were observed to vary diurnally and to be strongly influenced by tides. The time-averaged flux values show that such mixed-Spartina stands are insignificant ( 1%) global sources of H2S or CS2 and insignificant contributors to the global OCS cycle (< 1%). These results demonstrate that some marsh regions play a minor role in the global sulfur budget and, consequently, that the inclusion of such areas in extrapolations of measurements of more productive regions could lead to an overestimate of the role of salt water marshes in the global sulfur budget.  相似文献   

6.
Carbonyl sulfide emissions from biomass burning have been studied during field experiments conducted both in an African savanna area (Ivory Coast) and rice fields, central highland pine forest and savanna areas in Viet-Nam. During these experiments CO2, CO and C2H2 or CH4 have also been also monitored. COS values range from 0.6 ppbv outside the fires to 73 ppbv in the plumes. Significant correlations have been observed between concentrations of COS and CO (R 2=0.92,n=25) and COS and C2H2 (R 2=0.79,n=26) indicating a COS production during the smoldering combustion. COS/CO2 emission factors (COS/CO2) during field experiments ranged from 1.2 to 61×10–6 (11.4×10–6 mean value). COS emission by biomass burning was estimated to be up to 0.05 Tg S/yr in tropics and up to 0.07 Tg S/yr on a global basis, contributing thus about 10% to the global COS flux. Based on the S/C ratio measured in the dry plant biomass and the COS/CO2 emission factor, COS can account for only about 7% of the sulfur emitted in the atmosphere by biomass burning.  相似文献   

7.
Emissions of marine biogenic sulfur to the atmosphere of northern Europe   总被引：1，自引：0，他引：1  
Measurements of DMS and other reduced sulfur compounds in surface waters have been carried out from a helicopter in the seas surrounding Scandinavia. Average summer time concentrations of DMS ranged from 70 to 150 ngS L-1. Simultaneous measurements of biological and physical parameters revealed no correlation between DMS and phytoplankton species, species assemblages, total phytoplankton biomass, chlorophyll a, temperature, and salinity. The only exception was a correlation between DMS concentration, Chrysochromulina spp. belonging to the Prymnesiophyceae, and salinity over a narrow range of salinity in the Baltic Sea.The flux of reduced sulfur to the atmosphere in July in this region is estimated to be 120–170 gS m-2 d-1 from the Baltic, 240–810 in the Kattegat/Skagerrak, and 120–690 in the North Sea. Annual fluxes are roughly 100 times higher than these daily fluxes. On an annual basis, biogenic sulfur emissions from the coastal seas are negligible (<1%) compared to the anthropogenic emissions in northern Europe. However, during the summer months, the biogenic sulfur emissions from the seas surrounding the Scandinavian peninsula are estimated to be as high as 20–70% of the anthropogenic emissions in Scandinavia. This makes it of interest to incorporate the biogenic emissions in calculations of long-range transport and deposition of sulfur within the region.Other volatile sulfur species, mainly methyl mercaptan, contribute about 10% of the total flux of reduced sulfur. Estimated fluxes of CS2 to the atmosphere ranged from 1 gS m-2 d-1 in the Baltic Sea to 6 gS m-2 d-1 in the North Sea. No emissions for H2S or COS were detected.  相似文献   

8.
A new sensitive method for measuring atmospheric concentrations of sulfur dioxide is presented. Samples are obtained using the mist chamber, which collects highly water-soluble gases with high efficiency, and concentrates them in a small volume of water. Particles are removed from the sampled air stream with a teflon filter, before it enters the mist chamber. After collection, the pH of the water is raised above pH 10 using sodium carbonate, then hydrogen peroxide (H2O2) is added to oxidize sulfur that may be present in the sulfur (IV) oxidation state, to sulfate. After a reaction time of at least 16 hours, the sulfate concentration is measured by ion chromatography. From the sulfate concentration, the water volume used in the mist chamber, and the volume of air sampled, the atmospheric concentration of SO2 is computed. The method is not sensitive to other atmospheric sulfur gases such as DMS, SC2, H2S, COS, or MSH. The estimated overall precision of the method is 10%. The detection limit at the present stage of technique development is approximately 20 ppt (parts per trillion, or 10-12 mol · mol-1) for a 45 minute sampling time, with lower concentrations being detectable with lower precision.  相似文献   

9.
Sulfur fluxes from bare soils, naturally vegetated surfaces and from several agricultural crops were measured at two mid-continent sites (Ames, Iowa and Celeryville, Ohio) and from one salt water marsh site (Cedar Island, North Carolina) during a field program conducted jointly by the NOAA Aeronomy Laboratory, Washington State University Laboratory for Atmospheric Research and University of Idaho Department of Chemistry during July and August 1985. The sites were chosen specifically because they had been characterized by previous studies (Anejaet al., 1979; Adamset al., 1980, 1981). The NOAA gas chromatographic/dynamic-enclosure measurements yielded bare soil surfaces fluxes from the mid-continent sites composed predominantly of COS, H2S, CH3–S–CH3 (DMS) and CS2, all of which were strongly correlated with air temperature. Net fluxes of approximately 5 and 15 ng S/m2 min were observed in Iowa and Ohio, respectively, at appropriate weighted mean July temperatures. These fluxes are roughly a factor of 10 smaller than the earlier measurements, the greatest difference being in the measurement of the H2S flux. The presence of growing vegetation was observed to measurably increase the flux of H2S, significantly increase that of DMS and to decrease that of COS. Sulfur fluxes in the Cedar Island environs were observed to be both spatially and temporally much more variable and to include CH3SH as a measurable contributor. Net fluxes, composed predominantly of DMS and H2S, were estimated to be about 300 ngS/m2min during August; again about a factor of 10 lower than previous estimates. All measurements were corroborated to within about a factor of 2 by those of the other participating laboratories.  相似文献   

10.
Concentrations of sulfur gases H2S and SO2 have been measured in the marine atmosphere over the Atlantic Ocean at various sites. Mean values of 40 ng H2S m-3 STP and 209 ng SO2 m-3 STP are the results of the measurements. A diurnal variation of H2S concentration was detected on the west coast of Ireland with nighttime concentrations of up to 200 ng H2S m-3 STP and values below detection limit (15 ng H2S m-3 STP) during daytime.  相似文献   

11.
Boundary-layer and free-troposphere measurements of sulfur dioxide, dimethyl sulfide, and carbon disulfide were made during transits of the central and southern Pacific Ocean between Hawaii and Australia. Sulfur dioxide was generally less than 100 pptv and highly variable with no correlation with respect to geographic location or altitude. Dimethyl sulfide in the boundary layer had a concentration range of <10 to 200 pptv. Highest concentrations of DMS were in the equatorial region of the southern hemisphere although the concentrations were dependent on location and meteorological regime. In the region of the Fiji Islands several boundary layer samples had SO2, DMS, and CS2. In 1989, additional SO2 measurements were made between Hawaii and the equator and to the west of Hawaii downwind of the Kilauea volcano plumes.Paper submitted to the 7th International Symposium of the Commission for Atmospheric Chemistry and Global Pollution on the Chemistry of the Global Atmosphere held in Chamrousse, France, from 5 to 11 September 1990.  相似文献   

12.
Shipboard measurements of atmospheric dimethyl sulfide were made during two transects along the east coast of the United States and at several stations in the Gulf of Maine. Limited measurements of carbon disulfide and hydrogen sulfide are also reported. The mean DMS mixing ratio was 29 pptv (=25, n=84, median 19 pptv) during the Atlantic transects, and 101 pptv (=67, n=77, median 79 pptv) in the Gulf of Maine. Distinct diurnal variations were found in the DMS data from the transects. The meteorology of the study area appears to control day-to-day differences in the magnitude of these diurnal variations, although rapid daytime oxidation is suggested in some cases. Diurnal variations were also evident in near-shore stations in the Gulf of Maine due to nocturnal boundary-layer inversion. Diurnal variation was not evident at other sites in the Gulf due to large scale changes in the atmospheric circulation pattern, which effectively masked any effects due to oxidation processes. Model simulations confirm that the DMS levels and diurnal variation found during the transects are not consistent with atmospheric oxidation processes alone. Atmospheric CS2 and H2S mixing ratios were less than 3 pptv during the transects, except for a single period of higher CS2 mixing ratios (reaching 11 pptv) during advection of continental air. Calculations of the flux of oceanic sulfur to the eastern United States show that the contribution of natural sulfur to the North American sulfur budget is small compared to anthropogenic sources.  相似文献   

13.
In order to study the concentrations of hydrogen peroxide (H2O2) and the factors controlling its concentrations, we monitored concentrations of H2O2 and other gases such as sulfur dioxide, ozone, and NO x as well as meteorological factors such as air temperature, relative humidity, and wind direction/speed during eight measurement periods from 2000 to 2002 in a Japanese red pine forest in Japan. The H2O2 concentrations ranged from below 0.01 to 1.64 ppb, and analysis of the diurnal variation in H2O2 concentration showed high concentrations around noon, and low concentrations in the morning and late afternoon. The H2O2 concentrations were high in early summer, when O3 concentration, temperature, and solar radiation were high, and were low in fall, when O3 concentration, temperature, and solar radiation were low. We propose that O3 concentration affects the production of H2O2 in the monitored region during the period under study, but that high H2O2 concentrations were sometimes caused by the transport of polluted air from urban regions. H2O2 concentrations decreased remarkably when SO2 concentrations increased by transported volcanic emission on Miyake Island. In the absence of the effects of SO2, H2O2 concentrations increased with increasing O3 concentration and temperature.  相似文献   

14.
The products of the 254 nm photolysis of ppm levels of DMDS have been studied as a function of the O2 partial pressure at 760 Torr (N2 + O2) and 298±2 K. The major sulfur containing compounds detected were SO2 and CH3SO3H (methane sulfonic acid, MSA) and the major carbon containing compounds were CO, HCHO, CH3OH and CH3OOH (methyl hydroperoxide). Within the experimental error limits the observed sulfur and carbon balances were approximately 100%. CH3OOH has been observed for the first time in such a photooxidation system. Its observation provides evidence for the formation of CH3 radicals by the further oxidation of the CH3S radicals formed in the primary photolysis step.From the behavior of the DMDS photolysis products as a function of the O2 partial pressure, O3 concentration and added OH radical source it is postulated that the further reactions of CH3SOH (methyl sulfenic acid), formed in the reaction OH + CH3SCCH3 CH3SOH + CH3S, are the main source of MSA in the 254 nm photolysis of DMDS.Some of the possible implications of the results of this study for the degradation mechanisms of other atmospherically important organic sulfur compounds, in particular DMS, are briefly considered.  相似文献   

15.
Using the chemical composition of snow and ice of a central Greenland ice core, we have investigated changes in atmospheric HNO3 chemistry following the large volcanic eruptions of Laki (1783), Tambora (1815) and Katmai (1912). The concentration of several cations and anions, including SO 4 2– and NO 3 – , were measured using ion chromatography. We found that following those eruptions, the ratio of the concentration of NO 3 – deposited during winter to that deposited during summer was significantly higher than during nonvolcanic periods. Although we cannot rule out that this pattern originates from snow pack effects, we propose that increased concentrations of volcanic H2SO4 particles in the stratosphere may have favored condensation and removal of HNO3 from the stratosphere during Arctic winter. In addition, this pattern might have been enhanced by slower formation of HNO3 during summer, caused by direct consumption of OH through oxidation of volcanic SO2.  相似文献   

16.
In 1978–1980 nine aircraft flights to an altitude of up to 15 km were made over western Europe. Sulfur dioxide was measured with a sensitive chemiluminescence method consisting of separate sampling and analysis stages and application of a wet chemical filter procedure (detection limit: 8 pptv SO2).The measurements performed in the upper troposphere and lower stratosphere lead to some unexpected results: (a) the meteorological conditions at the tropopause level have an important influence on the observed SO2 mixing ratio; (b) between the 500 mb and the actual tropopause level the SO2 mixing ratio is found to be <100 pptv, and weak vertical gradients of SO2 suggest only a small flux of tropospheric SO2 into the stratosphere; (c) increasing SO2 mixing ratios within the first kilometers of the stratosphere give strong support to a stratospheric source of SO2.In the light of improved one-dimensional models considering the vertical distribution of stratospheric sulfur compounds (Crutzen, 1981; Turco et al. 1981) it can be shown that the oxidation of organic sulfur compounds (e.g., OCS, CS2) seems to be a stratospheric source of SO2. Furthermore, the flux calculations based on the SO2 mixing ratios measured at the tropopause level indicate that the contribution of tropospheric (man-made) SO2 to the stratospheric aerosol layer is of only minor importance.  相似文献   

17.
Cascade impactor samples were collected over the Alaskan Arctic during the first three research flights of AGASP-II. These samples were analyzed using analytical electron microscopy to determine the morphology, mineralogy and elemental composition of individual particles. For analytical considerations, a typical impactor sample was run for approximately 20 min, thus giving excellent time resolution of discrete events.Samples collected during flights 201 and 202 consisted of stratospheric aerosol and lower-altitude haze samples. Stratospheric samples were characterized by moderate loadings of H2SO4 droplets with relatively few particles of other types. Samples collected in tropospheric haze layers generally exhibited light-to-moderate particle loadings. H2SO4 was again the most prevalent species, with crustal and anthropogenic particles also observed. One sample taken over south-central Alaska near the end of flight 203 showed high concentrations of solid crustal particles, with relatively little associated H2SO4. Giant particles larger than 5 m were occasionally observed in this aerosol. The composition of this material closely matches that of bulk ash from the Mt. Augustine volcano, which erupted 9–13 days before collection of this sample. This brings forth the possibility that pockets of ash-rich aerosol existed over parts of south and central Alska during the AGASP-II field mission. There is no evidence that these volcanic aerosols were present in the AGASP study area north of the Brooks Range.  相似文献   

18.
Products and mechanisms have been investigated for the reactions between dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) and the hydroxyl radical (OH) in the presence of NOx. All of the experiments were performed in a 480 L reaction chamber, applying Fourier transform infrared spectroscopy (FT-IR) and ion chromatography as the analytical techniques.In addition to the sulfur containing products that are known to be produced from the gas phase reaction between DMS and OH (SO2, dimethylsulfone, methylsulfonyl peroxynitrate, methanesulfonic acid, H2SO4), DMSO and methanesulfinic acid (CH3S(O)OH) were also observed as products. Only SO2, DMSO2 and methylsulfonyl peroxynitrate were found as sulfur containing products in the reaction between DMSO and OH. Based on these new results we propose a mechanism for the atmospheric oxidation of DMS and DMSO by OH radical.  相似文献   

19.
10Be is used as a spike of the natural background atmospheric aerosol to calculate the global flux of sulfur (FS) into the free troposphere. The sulfate and10Be concentrations determined in polar snow are compared. On the basis of an annual10Be production rate of 1.21 106 at.cm-2, a very low figure of 2.9 Tg S a-1 is calculated for FS, which suggests that most of the sulfur emitted at ground level remains in the boundary layer. The role of OCS in the upper tropospheric sulfur budget is reviewed. It is also shown that cataclysmic volcanic eruptions may disturb considerably for 1–2 years this vast background tropospheric sulfur reservoir.  相似文献   

20.
A chemistry module has been incorporated into a Lagrangian type model that computes the dynamics and microphysics of an orographical cloud formed in moist air flowing over the summit of Great Dun Fell (GDF) in England. The cloud droplets grow on a maritime aerosol which is assumed to be an external mixture of sea-salt particles and ammonium-sulfate particles. The dry particle radii are in the range 10 nm<r<1 µm. The gas-phase chemical reaction scheme considers reactions of nitrogen compounds that are important at night. The treatment of scavenging of gases into the aqueous phase in the model takes into account the different solubilities and accommodation coefficients. The chemistry in the aqueous phase focusses on the oxidation of S(IV) via different pathways.Sensitivity analyses have been performed to investigate deviations from gas-liquid equilibria according to Henry's law and also to study the influence of iron and of nitrogen compounds on the aqueous-phase oxidation of dissolved SO2. When addressing these questions, special attention has been given to the dependence on the droplet size distribution and on the chemical composition of the cloud condensation nuclei on which the droplets have formed. It was found that the oxidation of S(IV) via a chain reaction of sulfur radicals can be important under conditions where H2O2 is low. However, major uncertainties remain with respect to the interaction of iron with the radical chain. It was shown that mixing of individual cloud droplets, which are not in equilibrium according to Henry's law, can result in a bulk sample in equilibrium with the ambient air. The dependence of the aqueous-phase concentrations on the size of the cloud droplets is discussed for iron, chloride and NO3.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号