Budgets and turn-over times of atmospheric sulfur compounds

The paper starts by defining the time concepts ‘residence time’ ‘age’ and ‘turn-over time’ and by discussing their inter-relations briefly. Some basic comments about box models as applied to sulfur in the atmosphere are also presented. It is suggested that when using budgets to estimate overall fluxes the optimum size for such boxes should be about four times the product of the turn-over time and an average transport velocity.A brief review is made of previous estimates of atmospheric sulfur budgets of scales ranging from global down to about 100 km. Particular emphasis is put on the implied turn-over times (i.e. average residence times) for the different sulfur compounds. These estimates are compared with estimates of time scales made from observations and experiments and from the use of long range transport models. Such comparisons are complicated by possible deviations from exponential residence time distributions which make, for example, rate coefficients estimated for short transport times unrepresentative for the full life cycle of the molecules in the atmosphere.Based on the presently available data an estimate is presented of the overall turn-over times in the midlatitude atmosphere of man-made SO₂ and SO₄²⁻ and of the turn-over times with respect to the different transformation and removal processes. The estimated overall turn-over times of SO₂, SO₄²⁻ and sulfur (SO₂ + SO₄²⁻) in this climate are roughly 25, 80 and 50 h respectively. The turn-over time with respect to the different removal and transformation processes are generally somewhat more uncertain. For SO₂ the dry deposition, wet deposition and transformation to SO₄²⁻ correspond to turn-over times of about 60, 100 and 80 h respectively. These figures would imply that about 30% of the SO₂ is transformed to SO₄²⁻ before being deposited The time scales mentioned here represent average conditions for a particular type of climate and may not be applied directly to specific situations (e.g. seasons) in similar climates or to other climatic zones.Most of the sulfur budgets estimates utilized in this study apply to conditions in Europe. A plea is made for similar studies to be undertaken in other parts of the world In North America there may already be enough data available for such studies.     

Physical properties of atmospheric particulate sulfur compounds

Integral properties of the total aerosol—which are usually measured first—tend to be related to certain limited size ranges only and do not represent the aerosol in its entire particle size range. The connection between integral and differential properties will be discussed, as well as the consequences with respect to the presentation of total sulfur mass and the sulfur size distribution. The question of the mixture state will be discussed and data given for the internal and external mixture ratio of ammonium sulfate as the most abundant sulfur compound in aerosols. Finally, a discussion is given of the particle sizes which must be produced to maintain the observed aerosol size distribution by any nucleation processes converting sulfuric gases into particles.     

Photochemical oxidation of reduced sulfur compounds in an urban location based on short time monitoring data

This study examines the oxidation of reduced sulfur compounds (RSCs) in urban ambient air. The photochemical conversions of RSC (such as DMS, CS₂, H₂S, DMDS, and CH₃SH) to a further oxidized form (e.g., SO₂, MSA, and H₂SO₄) were assessed using a photochemical box model. For our model simulation of RSC oxidation, measurements were taken at an urban monitoring station in Seoul, Korea (37.6° N, 127° E) during three separate time periods (e.g., Sept. 17–18, Oct. 23, and Oct. 27–28, 2003). The results indicate that DMS and H₂S were the dominant RSCs with concentrations of 370 ± 140 and 110 ± 60 pptv, respectively. The photochemical conversion of DMDS to SO₂ was found to occur more efficiently than other RSCs. The overall results of our study suggest that photochemical conversion of RSCs accounted for less than 15% of the observed SO₂ during the measurement period. The SO₂ production from DMS oxidation (mainly by the reaction with OH) was found to be affected primarily by the abstraction channel due to high NO_x levels during the experimental conditions.     

Photochemical oxidation and dispersion of gaseous sulfur compounds from natural and anthropogenic sources around a coastal location

The photochemical oxidation and dispersion of reduced sulfur compounds (RSCs: H₂S, CH₃SH, DMS, CS₂, and DMDS) emitted from anthropogenic (A) and natural (N) sources were evaluated based on a numerical modeling approach. The anthropogenic emission concentrations of RSCs were measured from several sampling sites at the Donghae landfill (D-LF) (i.e., source type A) in South Korea during a series of field campaigns (May through December 2004). The emissions of natural RSCs in a coastal study area near the D-LF (i.e., source type N) were estimated from sea surface DMS concentrations and transfer velocity during the same study period. These emission data were then used as input to the CALPUFF dispersion model, revised with 34 chemical reactions for RSCs. A significant fraction of sulfur dioxide (SO₂) was produced photochemically during the summer (about 34% of total SO₂ concentrations) followed by fall (21%), spring (15%), and winter (5%). Photochemical production of SO₂ was dominated by H₂S (about 55% of total contributions) and DMS (24%). The largest impact of RSCs from source type A on SO₂ concentrations occurred around the D-LF during summer. The total SO₂ concentrations produced from source type N around the D-LF during the summer (a mean SO₂ concentration of 7.4 ppbv) were significantly higher than those (≤0.3 ppbv) during the other seasons. This may be because of the high RSC and SO₂ emissions and their photochemistry along with the wind convergence.     

Concentration of sulfur compounds in remote continental and oceanic areas

The results of concentration measurements of atmospheric sulfur dioxide and sulfate particles carried out near the Earth's surface under background conditions are compiled. The data for continental (mainly Europe and North America) and oceanic (mainly Atlantic Ocean) areas are discussed. On the basis of the available information the sulfur quantities in an air column and in the whole atmosphere over continents and oceans are calculated. Some data on the H₂S concentration in the air are also presented.     

Concentration and dry deposition of atmospheric sulfur and nitrogen compounds in Hungary

The level of regional air pollution is regularly monitored at three stations in Hungary. The comparison of regional concentrations of SO₂ and NO₂ to those measured in Budapest shows that urban level concentration of SO₂ is ten times higher than the value for background conditions. The corresponding figure for NO₂ is five. An increase eastwards across the country can be observed for NO₂ and SO₂, while particulate sulphate, nitrate and ammonium have practically identical concentrations. The concentration of gaseous ammonia has a summer maximum, while the annual variation of particulate ammonium suggests a winter maximum. The ratio of the level of nitric acid to aerosol nitrate is higher than unity in summer, while in winter it is less than 1. The dry deposition of sulfur and oxidized nitrogen compounds is comparable to their wet deposition. However, in the case of NH_x (x = 3 or 4) the wet deposition exceeds the dry deposition by an order of magnitude.     

Monitoring of reduced sulfur compounds in the atmosphere of Gosan, Jeju Island during the Spring of 2001

The atmospheric concentrations of dimethylsulfide (DMS) and carbon disulfide (CS2) were measured concurrently with relevant environmental parameters at Gosan, Jeju Island, Korea during 5-26 April 2001. The mean concentrations for these two compounds were 18.7+/-17.9 and 6.4+/-9.9 pptv, respectively. Results of our analysis indicated that relative temporal variations between DMS and CS2 can be best described by dividing the whole data set into three different periods which reflect the variable transport patterns of air masses into the study area. (Periods I, II, and III denote: 5-10, 10-18, and 19-26 April.) The environmental conditions during those three periods varied greatly. The effects of continental and/or oceanic processes were evident for certain periods, yielding diverse relationships between DMS and CS2 in both absolute and relative terms. Most observed variations were best explained in terms of an interplay between source/sink processes and air mass transport patterns. The sea-to-air flux of DMS, when estimated using our measurement data during this study period, was approximately 4 micromole m(-2)d(-1).     

Concentrations of organotin compounds in sediment and clams collected from coastal areas in Vietnam

Levels of butyltin (BT) and phenyltin (PT) compounds were determined in sediments and clam Meretrix spp. collected from north and central coastal areas in Vietnam. Concentrations of TBT in sediments ranged from 0.89 to 34 ng g(-1) dry wt and those in clams ranged from 1.4 to 56 ng g(-1) wet wt. The levels of TBT in sediments and clams from Vietnam were within limits reported from other countries. Further, the TBT level in clams was lower than the tolerable average residue level (TARL) estimated based on tolerable daily intake (TDI). Trace amounts of PTs were also found in both sediment and clam samples. In sediments from north and central Vietnam, the concentrations of TBT were highest in the order of Hue (28 ng g(-1) dry wt), Cua Luc (15 ng g(-1) dry wt), Sam Son (6.3 ng g(-1) dry wt), and Tra Co (5.5 ng g(-1) dry wt). Among the clams from north and central Vietnam, the levels of TBT in clams from Cua Luc were dramatically high at 47 ng g(-1) wet wt. TBT formed the principal butyltin species in sediment at all sites studied. The ratios of TBT in sediment were higher among BT compounds at all study sites. Of total BTs, TBT was the dominant species in clams from almost all sites studied. In spatial distribution, TPT showed a pattern similar to TBT, suggesting the use of TPT as an antifouling paint. The partition coefficient between sediment and calms was calculated. The partition coefficients of TBT and TPT were 2.01 (0.56-5.5) and 9.23 (3.1-20), respectively. These results show that sediment-bound TBT is a source of contamination to clams in addition to dissolved TBT.     

PTR-MS measurement of partition coefficients of reduced volatile sulfur compounds in liquids from biotrickling filters

Biological air filtration for reduction of emissions of volatile sulfur compounds (e.g., hydrogen sulfide, methanethiol and dimethyl sulfide) from livestock production facilities is challenged by poor partitioning of these compounds into the aqueous biofilm or filter trickling water. In this study, Henry’s law constants of reduced volatile sulfur compounds were measured for deionized water, biotrickling filter liquids (from the first and second stages of a two-stage biotrickling filter), and NaCl solutions by a dynamic method using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) at a temperature range of 3–45 °C. NaCl solutions were used to estimate salting-out constants up to an ionic strength of 0.7 M in order to evaluate the effect of ionic strength on partitioning between air and biofilter liquids. Thermodynamic parameters (enthalpy and entropy of phase exchange) were obtained from the measured partition coefficients as a function of temperature. The results show that the partition coefficients of organic sulfur compounds in the biotrickling filter liquids were generally very close to the corresponding partition coefficients in deionized water. Based on the estimated ionic strength of biofilter liquids, it is assessed that salting-out effects are of no importance for these compounds. For H₂S, a higher enthalpy of air–liquid partitioning was observed for 2nd stage filter liquid, but not for 1st stage filter liquid. In general, the results show that co-solute effects for sulfur compounds can be neglected in numerical biofilter models and that the uptake of volatile sulfur compounds in biotrickling filter liquids cannot be increased by decreasing ionic strength.     

Spatial and diel variability in the emissions of some biogenic sulfur compounds from a Florida Spartinaalterniflora coastal zone

Emission rates of the biogenic reduced sulfur gases dimethyl sulfide, dimethyl disulfide, carbon disulfide and hydrogen sulfide were measured from several environments within a Florida Spartina alterniflora coastal zone. Spatial and diel variability was observed in the emission rates of all the sulfur gases. The speciation and magnitude of sulfur emissions can be related to site elevation and the spatial variability of vegetation coverage. Dimethyl sulfide appears to be a metabolic byproduct of S. alterniflora.     

Input of atmospheric sulfur by dry and wet deposition to two central European forest ecosystems

The total input of atmospheric sulfur to a beech and a spruce forest in the Federal Republic of Germany has been measured over a period of 6 years. The contribution of dry deposition to the total input was determined indirectly by comparing seasonal changes in the sulfur flux coupled with precipitation beneath the canopy of the deciduous beech forest. As a result of these investigations seasonal and annual sulfur fluxes are reported corresponding to removal rates of atmospheric sulfur. The experimental data show clearly that the removal rates depend upon the quality of the atmosphere/ land interface, in forested areas from the tree species forming the canopy. The 6-years average of total deposition on bare soil is 23kg S ha⁻¹ y⁻¹, on a beech forest 47–51 kg S ha⁻¹y⁻¹, on a spruce forest 80–86 kg S ha⁻¹ y⁻¹. Based upon the experimental results the role of the forest vegetation in the removal of sulfur from the atmosphere in the area of the Federal Republic of Germany is considered. The figures indicate, that at least 50% of the total sulfur deposition takes place on forested areas which cover only 28% of the total land surface.     

Perfluorinated compounds in water, sediment, soil and biota from estuarine and coastal areas of Korea

Soil, sediment, water, and biota collected from the western coast of Korea were analyzed to determine occurrence and sources of perfluorinated compounds (PFCs). PFCs were significantly concentrations of PFCs were measured in some water and biological samples, while concentrations of PFCs in soils and sediments were relatively low. The most widely detected compound was found to be perfluorooctanesulfonate (PFOS), with a maximum concentration in water of 450 ng/L and in fish of 612 ng/g, dw. PFOS concentrations in water and biota were both less than those thought to cause toxicity. However, in both cases concentrations were within a factor of 10 of the toxicity threshold concentration. Concentrations of PFCs were significantly greater downstream than those upstream on the same river, suggesting point sources. Overall, the detection of PFCs at relatively great concentrations in various environmental matrixes from this region of Korea suggests that further studies characterizing PFCs and their potential risk to both humans and wildlife are needed.     

阳极氧化联合电-Fenton氧化深度处理垃圾渗滤液

采用多孔碳素阴极、Ti/SnO2-Sb2O5-IrO2阳极构建电化学氧化系统用于渗滤液的深度处理。研究结果表明,所构建的电化学氧化系统通过阳极氧化和电-Fenton氧化2种机制降解有机污染物;处理过程中阴极表面形成的沉淀物对TOC和COD的衰减也产生了影响。在阴极电位为-1.0 V、Fe2+ 初始浓度为0.5 mmol/L的条件下,电化学处理120 min获得了58% 的TOC去除;处理480 min COD去除率为55%,NH3-N去除率为99%,TN去除率为60%,色度几乎被完全去除。GC-MS分析结果表明,渗滤液中以腐殖质类物质为主的有机化合物被降解为分子量相对较小的有机物,直至完全矿化。联合阳极氧化和电-Fenton氧化机制的电化学处理方法为垃圾渗滤液深度处理提供了新的选择。     

Identification of some plasticizers compounds in landfill leachate

In this work it was described a simple method for extraction of plasticizer compounds (mainly phthalate esters and bisphenol A (BPA)) from landfill leachate samples. The samples were submitted to an extraction procedures based on precipitation, solid phase extraction (SPE) and ionic exchange chromatography (IEC). Firstly the landfill leachate sample was acidified by addition of HCl concentrated, in order to precipitate the organic compounds that are less soluble in water. The precipitate was washed with several solvents. The aqueous phase was then submitted to SPE with XAD-4 resin and IEC with Amberlyst A-27 resin. The instrumental analysis was performed by gas chromatography with mass spectrometer detector (GC/MSD) and the compounds were identified by the GC/MSD library (Wiley) and by using some standard substances. These methodologies allow the isolation and identification of the following compounds: dioctylphthalate, diisobutilphthalate, BPA, benzoic acid, palmitic acid and diisopentylphthalate. The methods are very simple, rapid and selective, for plasticizers extraction from landfill leachate matrices.     

Identification of organic compounds in municipal landfill leachates

Forty-five organic compounds have been identified in leachates from a Swedish municipal landfill. The samples were taken from the interior of the landfill to minimize alterations caused by contact with the surroundings and were identified and quantified by gas chromatography combined with mass spectrometry. Two analytical procedures were used, one for priority pollutants, the other for a wider range of phenolic and neutral compounds and acids. Analyses of the leachates for water quality parameters indicated that the part of the landfill which was sampled had reached an anaerobic stage in which methane was being produced. Possible origins for most of the compounds identified have been suggested.     

不同生物覆盖层厚度对甲烷氧化的影响研究

利用和强化垃圾填埋场生物覆盖层的甲烷氧化能力是控制垃圾填埋场温室气体排放的一种经济和有效的手段。以陶粒和堆肥复合基质生物覆盖层为研究对象,采用实验室模拟柱试验方法对不同厚度(30～80 cm)生物覆盖层的甲烷氧化行为进行为期4个月的研究。试验结果表明,不同厚度生物覆盖层的甲烷氧化速率以30 cm厚度最佳;生物覆盖层氧气的空间分布与柱中甲烷氧化活动有显著的交互影响;以碳同位素(δ13C)测得80 cm生物覆盖层中甲烷的氧化率为41.73%。     

The influence of hydroxyl volatile organic compounds on the oxidation of aqueous sulfur dioxide by oxygen

Although the effect of volatile organic compounds (VOCs) on the oxidation of dissolved sulfur dioxide by oxygen has been the subject of many investigations, this is the first study which examines the effect of a large number of precisely 16 hydroxy compounds. The kinetics both in the absence and the presence of VOCs was defined by rate laws (A and B): A $$ \hbox{-} \mathrm{d}\left[\mathrm{S}\left(\mathrm{IV}\right)\right]/\mathrm{dt}={R}_o={k}_o\left[\mathrm{S}\left(\mathrm{IV}\right)\right] $$ B $$ \hbox{-} \mathrm{d}\left[\mathrm{S}\left(\mathrm{IV}\right)\right]/\mathrm{dt}={R}_i={k}_i\left[\mathrm{S}\left(\mathrm{IV}\right)\right] $$ where R _o and k _o are the initial rate and first-order rate constant, respectively, in the absence of VOCs, R _i , and k _i are the initial rate and the first-order rate constant, respectively, in the presence of VOCs, and [S(IV)] is the concentration of dissolved sulfur dioxide, sulfur(IV). The nature of the dependence of k _i on the concentration of inhibitor, [Inh], was defined by Eq. (C). C $$ {k}_i={k}_0/\left(1+B\left[\mathrm{Inh}\right]\right) $$ where B is an empirical inhibition parameter. The values of B have been determined from the plots of 1/k _i versus [Inh]. Among aliphatic and aromatic hydroxy compounds studied, t-butyl alcohol and pinacol were without any inhibition effect due to the absence of secondary or tertiary hydrogen. The values of inhibition parameter, B, were related to k _inh , the rate constant for the reaction of SO₄ ^? radical with the inhibitor, by Eq. (D). D $$ B=\left(9\pm 2\right)\times 1{0}^{-4}\times {k}_{inh} $$ Equation (D) may be used to calculate the values of either of B or k _inh provided that the other is known. The extent of inhibition depends on the value of the composite term, B[Inh]. However, in accordance with Eq. (C), the extent of inhibition would be sizeable and measurable when B[Inh]?>?0.1 and oxidation of S(IV) would be almost completely stopped when B[Inh]?≥?10. B[Inh] value can be used as a guide whether the reaction step: SO₄ ^??+?organics? \( \overset{k_{inh}}{\to } \) ?SO₄ ^2??+?non-chain products: should be included in the multiphase models or not.     

Effects of ammonia on methane oxidation in landfill cover materials

The effects of ammonia (NH₃) on CH₄ attenuation in landfill cover materials consisting of landfill cover soil (LCS) and aged municipal solid waste (AMSW), at different CH₄ concentrations, were investigated. The CH₄ oxidation capacities of LCS and AMSW were found to be significantly affected by the CH₄ concentration. The maximum oxidation rates for LCS and AMSW were obtained at CH₄ concentrations of 5 % and 20 %(v/v), respectively, within 20 days. CH₄ biological oxidation in AMSW was significantly inhibited by NH₃ at low CH₄ concentrations (5 %, v/v) but highly stimulated at high levels (20 % and 50 %, v/v). Oxidation in LCS was stimulated by NH₃ at all CH₄ concentrations due to the higher conversion of the nitrogen in NH₃ in AMSW than in LCS. NH₃ increases CH₄ oxidation in landfill cover materials.     

Do aerosols act as catalysts in the OH radical initiated atmospheric oxidation of volatile organic compounds?

Smog chamber/FTIR techniques were used to study the relative reactivity of OH radicals with methanol, ethanol, phenol, C₂H₄, C₂H₂, and p-xylene in 750 Torr of air diluent at 296±2 K. Experiments were performed with, and without, 500–8000 μg m⁻³ (4000–50 000 μm² cm⁻³ surface area per volume) of NaCl, (NH₄)₂SO₄ or NH₄NO₃ aerosol. In contrast to the recent findings of Oh and Andino (Atmospheric Environment 34 (2000) 2901, 36 (2002) 149; International Journal of Chemical Kinetics 33 (2001) 422) there was no discernable effect of aerosol on the rate of loss of the organic compounds via reaction with OH radicals. Gas kinetic theory arguments cast doubt upon the findings of Oh and Andino. The available data suggest that the answer to the title question is “No”. As part of this work the rate constants for reactions of OH radicals with methanol, ethanol, and phenol in 750 Torr of air at 296 K were determined to be: k_OH+CH3OH=(8.12±0.54)×10⁻¹³, k_OH+C2H5OH=(3.47±0.32)×10⁻¹² and k_OH+phenol=(3.27±0.31)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹.