Atmospheric SO2 Research Articles

Long-term effects of sheep-grazing and its removal on vegetation dynamics of British upland grasslands and moorlands; local management cannot overcome large-scale trends

The upland and mountainous regions of northern Europe provide a wide variety of ecosystem services. However, these ecosystem services are highly vulnerable to environmental and land-use change. To ensure their future conservation, it is therefore, essential to understand whether upland plant communities will respond positively or negatively to a range of environmental factors such as grazing pressure and landscape-scale factors such as changes in atmospheric SO2 and NOx deposition. To understand this, here, we describe the long-term trends in four UK upland communities (high-level grassland, intermediate grassland, blanket bog, high-level bog) using four replicated long-term experiments examining the effects of sheep grazing compared to no-sheep grazing in Moor House (from 1954 to 2016). Our results showed that species richness and abundance recovered in grazed plots after 2000, with improvements in species richness and abundance of vascular plants, mosses, and liverworts. Unfortunately, no improvement was found for lichens. Species richness, vascular plants, and mosses recovered the fastest, and much faster than liverworts. There was no evidence of slower recovery of species richness and abundance in plots where sheep grazing was removed. These results are consistent with longitudinal studies suggesting recovery after 2000 as a result of reduced atmospheric deposition. Although trends in diversity and abundance in the grazed and ungrazed plots were not identical, they were not markedly different either. The similar richness and abundance trends in the grazed and ungrazed plots found in each plant community suggest that within-community dynamics may overcome initial differences between the grazing treatments over time. In contrast, differences in richness and abundance among plant communities over time suggest that some landscape-scale trends, such as those caused by a reduction in nutrient inputs, initiate community-dependent recovery.

Effects Of Environmental Factors And Atmospheric Pollution in the Incidence of Hospital Admissions of Patients With Stroke In São Paulo City By Stroke In São Paulo City

Introduction: Stroke is one of the major causes of morbidity and mortality worldwide, difficult to treat and recover. The risk of developing stroke may be associated with environmental factors. Objective: To analyze the association between ambient temperature, air humidity and atmospheric pollution with the incidence of hospital admissions for stroke in the city of São Paulo in 2016. Methods: This is an ecological study, carried out by secondary data collection in the city of São Paulo in 2016. The definition of Stroke was according to the tenth revision of the International Classification of Diseases in codes: I60, I61, I63 and I64. Results: There was a positive correlation between the incidence of hospital admissions for stroke and in SO2 in air (rho: 0.80, p=0002) in women. In men there was a positive correlation between the number of hospital admission and SO2 concentration (rho: 0.570, p=0.005). Conclusion: We observed a positive correlation between the incidence of stroke and the concentration of the atmospheric pollutant SO2, an important fact for the intervention in the dispersion of pollutants.

Attic dust: an archive of historical air contamination of the urban environment and potential hazard to health?

A comprehensive study of attic dust in an urban area is presented. Its entire life cycle, from determining historical emission sources to recognising the processes that take place in attic dust and its potential to impact human health is discussed. Its chemical composition and morphological characteristics of individual solid particles reflect past anthropogenic activities. High levels of Be-Cd-Cu-Sb-Sn-Pb-Te-Zn and occurrence of Cu-Zn shavings are typical for an industrial zone characterised by a foundry and a battery factory. High levels of Co-Fe-Mo-Ni-W-Ba-Cr-Mg-Mn-Nb-Ti and occurrence of various solid Fe-oxides, particularly spherical particles, were identified in another industrial zone, which was dominated by the automotive and metal-processing industries. Emissions from coal combustion affected the distribution of S-Se-Hg-Tl-As-Ag-U. The predominant mineral in attic dust is gypsum, which was presumably formed in situ by the reaction of carbonate dust particles and atmospheric SO2 gas. The high oral bioaccessibility of As-Cd-Cu-Pb-Zn in the gastric phase and high bioaccessibility of As-Cu-Cd-Ni in the gastrointestinal phase were identified. Determined characteristics of attic dust and identified possibilities of prolonged human exposure to it indicate that attic dust should be treated as an excellent proxy for historical air contamination as well as a potentially hazardous material for human health.

Airborne microbial community structure and potential pathogen identification across the PM size fractions and seasons in the urban atmosphere

As a vital component of airborne bioaerosols, bacteria and fungi seriously endanger human health as pathogens and allergens. However, comprehensive effects of environmental variables on airborne microbial community structures remain poorly understood across the PM sizes and seasons. We collected atmospheric PM1.0, PM2.5, and PM10 samples in Hefei, a typical rapidly-developing city in East China, across three seasons, and performed a comprehensive analysis of airborne microbial community structures using qPCR and high-throughput sequencing. Overall the bacterial and fungal abundances in PM1.0 were one to two orders of magnitude higher than those in PM2.5 and PM10 across seasons, but their α-diversity tended to increase from PM1.0 to PM10. The bacterial gene abundances showed a strong positive correlation (P < 0.05) with atmospheric SO2 and NO2 concentrations and air quality index. The bacterial gene abundances were significantly higher (P = 0.001) than fungi, and the bacterial diversity showed stronger seasonality. The PM sizes influenced distribution patterns for airborne microbial communities within the same season. Source-tracking analysis indicated that soils, plants, human and animal feces represented important sources of airborne bacteria with a total relative abundance of more than 60% in summer, but total abundance from the unidentified sources surpassed in fall and winter. Total 10 potential bacterial and 12 potential fungal pathogens were identified at the species level with the highest relative abundances in summer, and their abundances increased with the PM sizes. Together, our results indicated that a complex set of environmental factors, including water-soluble ions in PM, changes in air pollutant levels and meteorological conditions, and shifts in the relative importance of available microbial sources, acted to control the seasonal compositions of microbial communities in the urban atmosphere.

Sulfur Compounds in Regulation of Stomatal Movement.

Sulfur, widely present in the soil and atmosphere, is one of the essential elements for plants. Sulfate is a dominant form of sulfur in soils taken up by plant roots. In addition to the assimilation into sulfur compounds essential for plant growth and development, it has been reported recently that sulfate as well as other sulfur containing compounds can also induce stomatal movement. Here, we first summarized the uptake and transport of sulfate and atmospheric sulfur, including H2O and SO2, and then, focused on the effects of inorganic and organic sulfur on stomatal movement. We concluded all the transporters for different sulfur compounds, and compared the expression level of those transporters in guard cells and mesophyll cells. The relationship between abscisic acid and sulfur compounds in regulation of stomatal movement were also discussed.

An Interdisciplinary Approach to Predicting the Effects of Transboundary Atmospheric Transport to Northwest European Neighboring States

The Kola North is the most industrial territory of the Arctic region, where enterprises are sources of sulfur dioxide (SO2), which disperses widely not only throughout the Kola North, but also to the territories of neighboring Northwest European countries: Norway and Finland. The purpose of this study was to reveal the main sources of atmospheric SO2 pollution in the Kola North, assess the possible contribution of SO2 to the morbidity of respiratory diseases among children in the region, study the daily dynamics of SO2 content, and examine the likelihood of transboundary transport to neighboring states. The pathways of SO2 transfer throughout 2020 were revealed by using daily data about SO2 surface mass, wind direction and speed selected from the Geographic Information System for the cities of Zapolyarny (69∘24′55″ N, 30∘48′48″ E) and Olenegorsk (68∘08′35″ N, 33∘ 15′10″ E). It was found that the prevalence of pneumonia in 0-14-year-old children was associated with Olenegorsk, where the maximum of SO2 emissions was detected. The median values of SO2 surface mass were 2.7 times higher for Olenegorsk than for Zapolyarny and exceeded the maximum permissible concentration. The probability of SO2 transport to the territories of Norway and Finland was also estimated. This study highlights the complexity of the problem of transboundary airborne pollution transport, which requires interdisciplinary research to predict the consequences of the contamination for territories of the neighboring Northwest European countries.&#x0D; Keywords: Kola North, sulfur dioxide, respiratory morbidity among children, transboundary atmospheric transport, neighboring states

No detection of SO2, H2S, or OCS in the atmosphere of Mars from the first two Martian years of observations from TGO/ACS

Context. The detection of sulphur species in the Martian atmosphere would be a strong indicator of volcanic outgassing from the surface of Mars. Aims. We wish to establish the presence of SO2, H2S, or OCS in the Martian atmosphere or determine upper limits on their concentration in the absence of a detection. Methods. We perform a comprehensive analysis of solar occultation data from the mid-infrared channel of the Atmospheric Chemistry Suite instrument, on board the ExoMars Trace Gas Orbiter, obtained during Martian years 34 and 35. Results. For the most optimal sensitivity conditions, we determine 1σ upper limits of SO2 at 20 ppbv, H2S at 15 ppbv, and OCS at 0.4 ppbv; the last value is lower than any previous upper limits imposed on OCS in the literature. We find no evidence of any of these species above a 3σ confidence threshold. We therefore infer that passive volcanic outgassing of SO2 must be below 2 ktons day−1.

Study of CMAS infiltration and evaporation behaviour under water vapour/sulphur oxide conditions in EB-PVD 7YSZ

The infiltration behaviour of CaO-MgO-Al2O3-SiO2 (CMAS) in Electron Beam Physical Vapour Deposited (EB-PVD) 7 wt% yttria stabilised zirconia (7YSZ) under controlled atmospheres (dry, wet and sulphurizing) was studied in detail. The microstructure of the CMAS-infiltrated 7YSZ and the CMAS residue on top were analysed to interpret the corrosion mechanisms. One of the major goals was to investigate the stability and the infiltration of CaSO4 into the 7YSZ columns. At the testing temperature of 1250 °C, CaSO4 was stabilised only under the SO2 atmosphere within the TBC coating and only in CaSO4-containing CMAS. Hydroxylation of CMAS elements was found under wet conditions, which changed the local CMAS composition and infiltration behaviour. These chemistry changes have provoked acidity changes in the CMAS which directly affected their aggressivity and viscosity. Thermodynamic equilibrium predictions on the volatility of CMAS components and the anhydrite stability under various atmospheres were used to understand the experimental findings and the underlying mechanisms.

INFLUENCE OF INTERNAL CIRCULATION ON ABSORPTION OF ATMOSPHERIC CO2 AND SO2 IN RAINDROP

INFLUENCE OF INTERNAL CIRCULATION ON ABSORPTION OF ATMOSPHERIC CO2 AND SO2 IN RAINDROP

Absorption spectra measurements at ~1 cm&lt;sup&gt;–1&lt;/sup&gt; spectral resolution of &lt;sup&gt;32&lt;/sup&gt;S, &lt;sup&gt;33&lt;/sup&gt;S, &lt;sup&gt;34&lt;/sup&gt;S, and &lt;sup&gt;36&lt;/sup&gt;S sulfur dioxide for the 206–220 nm region and applications to modeling of the isotopic self-shielding

The sulfur isotope fractionation that occurs during SO2 photolysis is key to explaining the isotope signatures stored in ancient sedimentary rocks and understanding the atmospheric compositions of the early Earth and early Mars. Here, we report the photoabsorption cross-sections of 32SO2, 33SO2, 34SO2, and 36SO2 measured from 206 to 220 nm at 296 K. The wavelength resolution was set to 1 cm–1, 25 times higher than that of previous SO2 isotopologue absorption spectra measurements. The precision of ~10% is in agreement with previously reported SO2 absorption spectra. In comparison with previously reported high-resolution spectra of natural abundance, SO2 measurements demonstrate smaller cross-sectional magnitudes at absorption peaks and an offset wavelength by ~0.016 nm. Using the newly recorded isotopologue spectra, we calculated the sulfur isotope fractionation for self-shielding during SO2 photolysis. The calculated 34S fractionation (34ε) roughly reproduces the observed relationship between 34ε and the SO2 column density in previous photolysis experiments. Thus, the cross-section is useful for predicting 34S/32S isotope fractionation in an optically thick SO2 atmosphere. In contrast, for mass-independent fractionation (MIF-S, i.e., non-zero Δ33S), the measured spectra predicted a weakly negative Δ33S/δ34S slope of about –0.1. The small Δ33S/δ34S slope is consistent with the slopes of SO2 photolysis experiments under high-pressure atmospheres (i.e., the pressure broadened absorption line width will be comparable to the spectral resolution). Therefore, MIF-S during photolysis experiments was linked to spectroscopic measurements for the first time. We conclude that reasonable precision and high-resolution spectroscopic measurements are key to explaining the origin of MIF-S at column densities below 1018 cm–2. However, MIF-S production in chamber experiments or atmospheric conditions may require understanding pressure or temperature effects, such as linewidth broadening on the UV-absorption spectra, and how these effects manifest themselves on isotopologues.

Evaluation of SO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;, SO&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;&amp;lt;sup&amp;gt;2−&amp;lt;/sup&amp;gt; and an updated SO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; dry deposition parameterization in the United Kingdom Earth System Model

Abstract. In this study we evaluate simulated surface SO2 and sulfate (SO42-) concentrations from the United Kingdom Earth System Model (UKESM1) against observations from ground-based measurement networks in the USA and Europe for the period 1987–2014. We find that UKESM1 captures the historical trend for decreasing concentrations of atmospheric SO2 and SO42- in both Europe and the USA over the period 1987–2014. However, in the polluted regions of the eastern USA and Europe, UKESM1 over-predicts surface SO2 concentrations by a factor of 3 while under-predicting surface SO42- concentrations by 25 %–35 %. In the cleaner western USA, the model over-predicts both surface SO2 and SO42- concentrations by factors of 12 and 1.5 respectively. We find that UKESM1’s bias in surface SO2 and SO42- concentrations is variable according to region and season. We also evaluate UKESM1 against total column SO2 from the Ozone Monitoring Instrument (OMI) using an updated data product. This comparison provides information about the model's global performance, finding that UKESM1 over-predicts total column SO2 over much of the globe, including the large source regions of India, China, the USA, and Europe as well as over outflow regions. Finally, we assess the impact of a more realistic treatment of the model's SO2 dry deposition parameterization. This change increases SO2 dry deposition to the land and ocean surfaces, thus reducing the atmospheric loading of SO2 and SO42-. In comparison with the ground-based and satellite observations, we find that the modified parameterization reduces the model's over-prediction of surface SO2 concentrations and total column SO2. Relative to the ground-based observations, the simulated surface SO42- concentrations are also reduced, while the simulated SO2 dry deposition fluxes increase.

Analysis of atmospheric SO2 in Sichuan-Chongqing region based on OMI data.

The Sichuan-Chongqing region is the leader and growth pole of economic development in western China. With the rapid development of economy and unique geographical environment, high concentration of sulfur dioxide air pollution has existed for a long time in Sichuan-Chongqing area. Based on 10years of remote sensing data, this paper studies the temporal and spatial distribution characteristics, stability, and influencing factors of sulfur dioxide in this area. Based on potential sources, the impact of surrounding areas on sulfur dioxide in Sichuan and Chongqing is analyzed. The results shows that the spatial distribution of sulfur dioxide in the Sichuan-Chongqing region is higher in the southeast and lower in the west. The Midwest region has low fluctuation and good stability. The time distribution shows obvious seasonal regularity. The concentration of sulfur dioxide is affected by socio-economic factors and natural factors. In this study, it is found that the distribution of sulfur dioxide is closely related to PM2.5, which provides an important reference for the comprehensive management of air pollution. The OMI data effectively reflects the distribution and change of atmospheric sulfur dioxide in the Sichuan-Chongqing region, and provides certain ideas for air pollution control in the Sichuan-Chongqing region and other regions in China.

Interannual variation of reactive nitrogen emissions and their impacts on PM2.5 air pollution in China during 2005–2015

Emissions of reactive nitrogen as ammonia (NH3) and nitrogen oxides (NO x ), together with sulfur dioxide (SO2), contribute to formation of secondary PM2.5 in the atmosphere. Satellite observations of atmospheric NH3, NO2, and SO2 levels since the 2000s provide valuable information to constrain the spatial and temporal variability of their emissions. Here we present a bottom-up Chinese NH3 emission inventory combined with top-down estimates of Chinese NO x and SO2 emissions using ozone monitoring instrument satellite observations, aiming to quantify the interannual variations of reactive nitrogen emissions in China and their contributions to PM2.5 air pollution over 2005–2015. We find small interannual changes in the total Chinese anthropogenic NH3 emissions during 2005–2016 (12.0–13.3 Tg with over 85% from agricultural sources), but large interannual change in top-down Chinese NO x and SO2 emissions. Chinese NO x emissions peaked around 2011 and declined by 22% during 2011–2015, and Chinese SO2 emissions declined by 55% in 2015 relative to that in 2007. Using the GEOS-Chem chemical transport model simulations, we find that rising atmospheric NH3 levels in eastern China since 2011 as observed by infrared atmospheric sounding interferometer and atmospheric infrared sounder satellites are mainly driven by rapid reductions in SO2 emissions. The 2011–2015 Chinese NO x emission reductions have decreased regional annual mean PM2.5 by 2.3–3.8 μg m−3. Interannual PM2.5 changes due to NH3 emission changes are relatively small, but further control of agricultural NH3 emissions can be effective for PM2.5 pollution mitigation in eastern China.

Significant decrease in SO2 emission and enhanced atmospheric oxidation trigger changes in sulfate formation pathways in China during 2008–2016

Understanding the changes in the sulfate (SO42−) formation pathway is important to further control particle pollution owing to the significant reduction of SO2 emission and enhanced atmospheric oxidation. This study applied the Community Multiscale Air Quality (CMAQ) model coupled with the sulfur tracking model (STM) to quantify sources of atmospheric SO42− in China and their changes during 2008–2016. The results showed that the surface SO42− concentration decreased by 51.1%, 40.8%, 37.5%, and 36.2% for Beijing–Tianjin–Hebei (BTH), Yangtze River Delta (YRD), Pearl River Delta (PRD), and Sichuan Basin (SCB), respectively. In addition, the SO42− formation pathways also changed in a sustained manner. The gas-phase reaction of SO2 with OH (SO4_GAS) and the reaction catalyzed by Fe3+ and Mn2+ (SO4_FEMN) decreased significantly (63.4% and 61.7%), whereas the aqueous-phase reaction of SO2 with O3 (SO4_O3) increased by 39.9% from 2008 to 2016. Primary SO42− emission (SO4_EMIS) played an important role in autumn and winter with over 30% contribution, whereas SO4_GAS and the aqueous-phase reaction of SO2 with H2O2 (SO4_H2O2) dominated in spring and summer, respectively. The sensitivity simulation results showed that sharp SO2 reduction significantly decreased SO4_GAS (over 60%); however, it was less sensitive to SO4_O3 (8%–11%). In addition, the SO2 emission reduction resulted in a large increase in atmospheric NH3 concentrations due to less neutralization reaction, thus increasing NO3− concentration in some regions. These results suggest that multi-pollutants control for SO2-NOx-VOC should be implemented to prevent the enhanced atmospheric oxidation furtherly deteriorating secondary air pollution, particularly in spring and summer. In addition, limiting primary emissions from residential combustion in winter is important to achieve coordinated control of SO2 and SO42− in northern China.

Source apportionment of volatile organic compounds, CO, SO2 and trace metals in a complex urban atmosphere

A commixture of gasphase compounds including carbon monoxide (CO), sulphur dioxide (SO2), volatile organic compounds (VOCs) and trace metals were collected at a site located at the urban/industrial interface in Houston, Texas. Positive Matrix Factorization (PMF) analysis yielded nine factors: gas/crude oil (21.3±5.5%), isoprene emission (17.0±7.1%), Si-rich (14.6±1.3%), liquefied petroleum gas (LPG) (11.2±4.0%), traffic (10.6±0.4%), Fluidized-bed Catalytic Cracking (FCC)/high temperature operations (7.2±4.3%), oil refinery (6.8±0.9%), soil and road dust (6.2±0.6%), and petrochemical industries (5.0±5.0%). Daytime and nighttime PMF runs were carried out to see potential differences among and within emission sources. Notable findings include: (1) Nocturnal isoprene emission was identified from traffic exhaust and industrial sources. (2) LPG emissions were higher during the day most likely due to temperature dependent evaporative processes. (3) V/Ni and SO2/V ratios reveal greater contribution from crude oil in the merged natural gas/crude oil emission factor. Corrosion might be responsible for emitting metals (i.e., Cr, Cu, Mo, Ni) from oil refineries during nighttime. (4) In the soil and road dust factor, metals relevant to plant physiological processes are mostly retained by the plants while the lanthanoids and other metals (i.e. Y, Pb, Mn, Ga, Ba) are more prone to physical removal during the day. (5) FCC/high temperature operations are dominated by metals at night. (6) The traffic factor increases during the day possibly due to the higher number of vehicles. Bivariate polar plots suggest the Houston Ship Channel area as the primary emission source for LPG, natural gas/crude oil, FCC/high temperature operations, and petrochemical industries.

Rapid cloud removal of dimethyl sulfide oxidation products limits SO2 and cloud condensation nuclei production in the marine atmosphere

Oceans emit large quantities of dimethyl sulfide (DMS) to the marine atmosphere. The oxidation of DMS leads to the formation and growth of cloud condensation nuclei (CCN) with consequent effects on Earth's radiation balance and climate. The quantitative assessment of the impact of DMS emissions on CCN concentrations necessitates a detailed description of the oxidation of DMS in the presence of existing aerosol particles and clouds. In the unpolluted marine atmosphere, DMS is efficiently oxidized to hydroperoxymethyl thioformate (HPMTF), a stable intermediate in the chemical trajectory toward sulfur dioxide (SO2) and ultimately sulfate aerosol. Using direct airborne flux measurements, we demonstrate that the irreversible loss of HPMTF to clouds in the marine boundary layer determines the HPMTF lifetime (τHPMTF < 2 h) and terminates DMS oxidation to SO2 When accounting for HPMTF cloud loss in a global chemical transport model, we show that SO2 production from DMS is reduced by 35% globally and near-surface (0 to 3 km) SO2 concentrations over the ocean are lowered by 24%. This large, previously unconsidered loss process for volatile sulfur accelerates the timescale for the conversion of DMS to sulfate while limiting new particle formation in the marine atmosphere and changing the dynamics of aerosol growth. This loss process potentially reduces the spatial scale over which DMS emissions contribute to aerosol production and growth and weakens the link between DMS emission and marine CCN production with subsequent implications for cloud formation, radiative forcing, and climate.

Investigation on the Relationship between Satellite Air Quality Measurements and Industrial Production by Generalized Additive Modeling

The development of the green economy is universally recognized as a solution to natural resource shortages and environmental pollution. When exploring and developing a green economy, it is important to study the relationships between the environment and economic development. As opposed to descriptive and qualitative research without modeling or based on environmental Kuznets curves, quantitative relationships between environmental protection and economic development must be identified for exploration and practice. In this paper, we used the generalized additive model (GAM) regression method to identify relationships between atmospheric pollutants (e.g., NO2, SO2 and CO) from remote sensing and in situ measurements and their driving effectors, including meteorology and economic indicators. Three representative cities in the Anhui province, such as Hefei (technology-based industry), Tongling (resource-based industry) and Huangshan (tourism-based industry), were studied from 2016 to 2020. After eliminating the influence of meteorological factors, the relationship between air quality indexes and industrial production in the target cities was clearly observed. Taking Hefei, for example, when the normalized output of chemical products increases by one unit, the effect on atmospheric NO2 content increases by about 20%. When the normalized output of chemical product increases by one unit, the effect on atmospheric SO2 content increases by about 10%. When chemical and steel product outputs increase by one unit, the effect on atmospheric CO content increases by 25% and 20%, respectively. These results can help different cities predict local economic development trends varying by the changes in air quality and adjust local industrial structure.

A model for the kinetics of high-temperature reactions between polydisperse volcanic ash and SO2 gas

AbstractRapid calcium diffusion occurs in rhyolitic volcanic ash particles exposed to hot SO2 atmospheres. Such chemical transport is important immediately following fragmentation, during proximal transport in eruption plumes and during percolative gas transport through a permeable volcanic edifice. Here we analyze published results of experiments designed to constrain the kinetics of this process. The experiments involve crushed rhyolitic glass particles tumbled in SO2-bearing atmospheres at a wide range of relevant temperatures. We find that the particle-gas reaction is fed by calcium diffusion from the bulk to the particle surfaces where calcium-sulfate crystals grow. The calcium flux is accommodated by local iron oxidation state changes. This process results in time-dependent concentrations of surface calcium that are leachable in aqueous solutions. Those leachate concentrations represent a proxy for the diffusive flux of Ca2+ out of the particle to form the surface deposits. We formulate a mathematical framework to convolve the starting particle size distributions with the solution to Fickian one-dimensional diffusion to find a weighted polydisperse result. Using this framework, we minimize for a temperature-dependent calcium diffusivity and compare our results with published calcium diffusivity data. We demonstrate that calcium diffusivity in rhyolite can be decomposed into two regimes: (1) a high-temperature regime in which the diffusivity is given by the Eyring equation and (2) a low-temperature regime more relevant to rhyolite volcanism and these gas-ash reactions. As a further test of our model, we compare the output against spatially resolved data for the calcium gradients in the experimental particles. Our analysis suggests that surface reaction rates are rapid compared with the diffusion of calcium from the particle to the surface, such that full diffusion models must be solved to predict the rhyolite-SO2 reaction. We conclude by suggesting how this framework could be used to make quantitative predictions of sulfur budgets and iron oxidation during rhyolitic eruptions.

Weathering of materials at Notre-Dame from changes in air pollution and climate in Paris, 1325–2090

Notre-Dame, as with much historic architecture in Paris, has been exposed to the ravages of changing pollution and climate. Estimates of historic temperature, precipitation and relative humidity and concentrations of key atmospheric pollutants SO2 NO2, O3 and PM10 have been combined with projections under Intergovernmental Panel on Climate Change scenarios RCP2.6 and RCP8.5 to estimate long term soiling, recession and corrosion. The Lipfert function and dose response equations from the International Co-operative Programme on Effects on Materials were used to estimate long-term damage. The picture reveals that the effect of pollution is apparent from around 1700, though it increases notably after 1850; then most pollutant concentrations decreased through the latter half of the 20th century. The soiling predicted for sheltered surfaces follows this trend, although changes in wind direction and washing by rain can also alter the dark and light patterns. Buildings facades are likely to be cleaner over the present century, so we may well be sensitised to other changes that architectural surfaces undergo, e.g. changing patterns and forms of biological growth and parallel changes in colour, especially if surfaces remain wet for substantial periods. In the coming century, decreasing snow fall and longer times of wetness could enhance recession and corrosion rates. While metals in general are likely to corrode less in future compared to the 20th century, some such as copper would be sensitive to any increases in ozone concentrations. Lead used as new roofing for Notre-Dame can be mobilised, increasing heavy metal concentrations in the local environment.

Attrition performance and morphology of limestone under different conditions in fluidized bed

The attrition characteristics of limestone have an important influence on the material balance and the efficiency of desulfurization in circulating fluidized bed boiler. By means of XRD, XRF, SEM and BET analysis, the attrition behaviour and morphology of two kinds of limestone with different particle sizes were studied by investigating the effects of simultaneous reaction of sulfation and calcination, sulfation reaction, oxygen-enriched flue gas atmosphere.The variation trend of attrition rate constant under simultaneous reaction is similar to that under only sulfation condition. Both of these conditions decrease with time and then reach a stable value. The attrition rate of finer limestone is higher than that of coarser limestone in a certain size range. The attrition rate of limestone in air atmosphere is the largest, while, in SO2 atmosphere it's far less. This is mainly caused by the formation of CaSO4 layer that reduces the attrition rate. By calculating the conversion of Ca to CaSO4, it is found that the conversion increases with time, but the increasing rate decreases gradually. The increase of SO2 concentration leads to the increase of final conversion. In the oxygen-enriched flue gas atmosphere, the limestone is more attrition-resistant than that in the air.