Global Sulfur Emissions Research Articles

Self-assembly of Dawson-type H6P2W18O62@[Cu6O(TZI)3(H2O)6]4 for high-performance aerobic oxidation desulfurization of fuel.

Because global sulfur emission has escalated, the development of high-efficiency deep desulfurization techniques has become imperative. Herein, to design a high-activity heterogeneous catalyst for the aerobic oxidation desulfurization (AODS) of fuel, Dawson-type polyoxometalate (H6P2W18O62 abbreviated as D-P2W18), characterized by its high activity and strong oxidative capacity, was applied to react with CuCl2·2H2O and H3TZI via a one-pot hydrothermal method. Consequently, blue crystalline H6P2W18O62@[Cu6O(TZI)3(H2O)6]4 (abbreviated as D-P2W18@rht-MOF-1; rht-MOF-1 = [Cu6O(TZI)3(H2O)6]4·nH2O) was afforded. X-ray diffraction analysis indicated that D-P2W18 was successfully encapsulated in two different cages of rht-MOF-1, which is distinct from the crystal structure of Keggin-type POMs@rht-MOF-1. It represents the first crystal structure of Dawson-type POMs@rht-MOF-1. When D-P2W18@rht-MOF-1 was employed as a catalyst for AODS under ambient oxygen pressure with the assistance of surfactant dioctadecyl dimethyl ammonium chloride (DODMAC), it demonstrated remarkable catalytic capability and recyclability for both model fuel and commercial diesel. Further, the AODS reaction mechanism, identified as a free radical oxidation-reduction process, was verified by way of radical quenching experiments, EPR and XPS analysis. This approach offers a feasible route for the synthesis of new Dawson-type POMs@MOFs of heterogeneous catalysts for highly active AODS of fuel.

Global nitrogen and sulfur deposition mapping using a measurement–model fusion approach

Abstract. Global reactive nitrogen (N) deposition has more than tripled since 1860 and is expected to remain high due to food production and fossil fuel consumption. Global sulfur emissions have been decreasing worldwide over the last 30 years, but many regions are still experiencing unhealthily high levels of deposition. We update the 2010 global deposition budget for reactive nitrogen and sulfur components with new regional wet deposition measurements from Asia, improving the ensemble results of 11 global chemistry transport models from the second phase of the United Nations Economic Commission for Europe's Task Force on Hemispheric Transport of Air Pollution (HTAP II). The observationally adjusted global N deposition budget is 114.5 Tg N, representing a minor increase of 1 % from the model-only derived values, and the adjusted global sulfur deposition budget is 88.9 Tg S, representing a 6.5 % increase from the modeled values, using an interpolation distance of 2.5∘. Regionally, deposition adjustments can be up to ∼ 73 % for nitrogen and 112 % for sulfur. Our study demonstrates that a global measurement–model fusion approach can improve N and S deposition model estimates at a regional scale, with sufficient availability of observations; however, in large parts of the world, alternative approaches need to be explored. The analysis presented here represents a step forward toward the World Meteorological Organization's goal of global fusion products for accurately mapping harmful air pollution deposition.

A sulfur dioxide Covariance-Based Retrieval Algorithm (COBRA): application to TROPOMI reveals new emission sources

Abstract. Sensitive and accurate detection of sulfur dioxide (SO2) from space is important for monitoring and estimating global sulfur emissions. Inspired by detection methods applied in the thermal infrared, we present here a new scheme to retrieve SO2 columns from satellite observations of ultraviolet back-scattered radiances. The retrieval is based on a measurement error covariance matrix to fully represent the SO2-free radiance variability, so that the SO2 slant column density is the only retrieved parameter of the algorithm. We demonstrate this approach, named COBRA, on measurements from the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Sentinel-5 Precursor (S-5P) satellite. We show that the method reduces significantly both the noise and biases present in the current TROPOMI operational DOAS SO2 retrievals. The performance of this technique is also benchmarked against that of the principal component algorithm (PCA) approach. We find that the quality of the data is similar and even slightly better with the proposed COBRA approach. The ability of the algorithm to retrieve SO2 accurately is further supported by comparison with ground-based observations. We illustrate the great sensitivity of the method with a high-resolution global SO2 map, considering 2.5 years of TROPOMI data. In addition to the known sources, we detect many new SO2 emission hotspots worldwide. For the largest sources, we use the COBRA data to estimate SO2 emission rates. Results are comparable to other recently published TROPOMI-based SO2 emissions estimates, but the associated uncertainties are significantly lower than with the operational data. Next, for a limited number of weak sources, we demonstrate the potential of our data for quantifying SO2 emissions with a detection limit of about 8 kt yr−1, a factor of 4 better than the emissions derived from the Ozone Monitoring Instrument (OMI). We anticipate that the systematic use of our TROPOMI COBRA SO2 column data set at a global scale will allow missing sources to be identified and quantified and help improve SO2 emission inventories.

Bi-perspective sulfur abatement options to mitigate coastal shipping ships emissions: A Case Study of Chinese coastal zone

In response to global sulfur emission restrictions, China has established sulfur emission control areas in its coastal areas. This has a huge impact on China's coastal shipping ships. These ships can adopt the following three sulfur abatement options to deal with it: (1) using low-sulfur fuel, (2) using an exhaust gas cleaning system, and (3) using alternative fuel Liquefied Natural Gas (LNG). This paper has established two models from two different perspectives to analyze the differences of abatement options between the shipowners and the general public. Sensitivity analyses are carried out on the factors affecting the sulfur abatement options, including remaining lifespan of ships, ship power, initial cost of sulfur abatement options, and fluctuations in the price of fuel. By analyzing the impact of these factors on the choice of the shipowners to reduce sulfur emission, this paper proposes some incentives and subsidy policies accordingly, which can provide references for policymakers.

Real option analysis for emission reduction investment under the sulfur emission control

In order to reduce marine pollution, the International Maritime Organization proposes the latest global sulfur emission limits, which will have a huge impact on the global shipping industry. In this paper, the traditional DCF evaluation method is compared with the real option analysis methods such as BS model, binary tree model and Monte Carlo method, and the three schemes are analyzed and compared from the short-term and long-term perspectives respectively. The research results show that the real option method is a more realistic, reliable and promising method for evaluating emission reduction projects, especially in the case of uncertainties and volatility in the material resources market. The results of the study can be applied to the assessment of all items in the shipping industry that depend on changes in the price of the underlying asset over a specified period of time.

Measuring global sulfur dioxide emissions with satellite sensors

Atmospheric sulfur dioxide affects the weather by enhancing cloud formation, and long‐term shifts in emissions can change the climate by increasing the amount of solar radiation scattered back into space. Sulfur dioxide emissions are the basis for acid rain, and the gas itself can cause respiratory problems. Despite the compound's importance to climate, the difficulties associated with accurately measuring sulfur dioxide mean that rates of emissions are generally not well understood.

The Doubtful Environmental Benefit of Reduced Maximum Sulfur Limit in International Shipping Fuel

On January 1st, 2012, the maximum limit for sulfur concentration in marine fuels on the high seas was lowered from 4.50% to 3.50% by the International Maritime Organization (IMO). It was one of a series of planned steps toward reducing the negative environmental and health impacts of international shipping. This study investigates the effectiveness of the IMO regulation in reducing global sulfur emissions. We found a reduction in global average sulfur concentration of only 0.07% points from 2011 to 2012. On the positive side, we also found that only 2.3% of the bunkerings were noncompliant in 2012, that is, exceeded the new 3.50% sulfur concentration cap. The analysis furthermore suggests that compliance with the new regulation is achieved by blending high sulfur fuel with lower sulfur fuel, rather than by removing high sulfur fuel from the market or removing the excess sulfur. The main conclusion is that the regulation has been effective in reducing the maximum sulfur concentration but has not been very effective in reducing the average sulfur concentration. Thus, the regulation may have resulted in local environmental benefits but has not resulted in global benefits with respect to global sulfur emissions from international shipping.

Isotopic constraints on the formation pathways of sulfate aerosol in the marine boundary layer of the subtropical northeast Atlantic Ocean

We use observations of the oxygen‐17 excess of non‐sea salt sulfate aerosol (Δ17O(nssSO42−)) collected from two ship cruises in the subtropical northeast Atlantic Ocean in August 2006 and February 2007 to quantify the formation pathways of sulfate in the marine boundary layer (MBL). The large observed Δ17O(nssSO42−) values up to 7.3‰ suggest a large role for sulfate formation via S(IV) oxidation by O3 in the MBL. Model simulations with the GEOS‐Chem global chemical transport model suggest that in‐cloud oxidation of S(IV) by O3 represents over one‐third (36–37%) of total in‐cloud sulfate production on average. A model parameterization accounting for the impacts of sea salt aerosol on cloud droplet chemical heterogeneity and resulting impacts on in‐cloud sulfate production rates improves the model's agreement with the Δ17O(nssSO42−) observations in the MBL. Including this parameterization in the model had little impact on the global sulfur budget due to the dominant role of continental anthropogenic emissions for global sulfur emissions in the present‐day. The large observed Δ17O(nssSO42−) argue against a significant role of hypobromous (HOBr) or hypochlorous (HOCl) acid for sulfate formation in the remote MBL of the wintertime subtropical northeast Atlantic, but S(IV) oxidation by HOBr/HOCl on the order of 20% of total sulfate abundance is consistent with the summertime Δ17O(nssSO42−) observations in the more polluted coastal region of the Iberian Peninsula. Additional measurements of Δ17O(nssSO42−) are needed to quantify sulfate production mechanisms in the MBL over larger spatial and temporal scales.

Sources, distribution, and acidity of sulfate–ammonium aerosol in the Arctic in winter–spring

We use GEOS-Chem chemical transport model simulations of sulfate-ammonium aerosol data from the NASA ARCTAS and NOAA ARCPAC aircraft campaigns in the North American Arctic in April 2008, together with longer-term data from surface sites, to better understand aerosol sources in the Arctic in winter-spring and the implications for aerosol acidity. Arctic pollution is dominated by transport from mid-latitudes, and we test the relevant ammonia and sulfur dioxide emission inventories in the model by comparison with wet deposition flux data over the source continents. We find that a complicated mix of natural and anthropogenic sources with different vertical signatures is responsible for sulfate concentrations in the Arctic. East Asian pollution influence is weak in winter but becomes important in spring through transport in the free troposphere. European influence is important at all altitudes but never dominant. West Asia (non-Arctic Russia and Kazakhstan) is the largest contributor to Arctic sulfate in surface air in winter, reflecting a southward extension of the Arctic front over that region. Ammonium in Arctic spring mostly originates from anthropogenic sources in East Asia and Europe, with added contribution from boreal fires, resulting in a more neutralized aerosol in the free troposphere than at the surface. The ARCTAS and ARCPAC data indicate a median aerosol neutralization fraction [NH^(+)_(4)]/(2[SO^(2-)_(4)] + [NO^(-)_(3)]) of 0.5 mol mol^(-1) below 2 km and 0.7 mol mol^(-1) above. We find that East Asian and European aerosol transported to the Arctic is mostly neutralized, whereas West Asian and North American aerosol is highly acidic. Growth of sulfur emissions in West Asia may be responsible for the observed increase in aerosol acidity at Barrow over the past decade. As global sulfur emissions decline over the next decades, increasing aerosol neutralization in the Arctic is expected, potentially accelerating Arctic warming through indirect radiative forcing and feedbacks.

Between Estimates of the Environmental Kuznets Curve

Recent papers by Wagner in this journal and Vollebergh et al. in the Journal of Environmental Economics and Management point out some fundamental econometric problems with traditional methods of estimating the environmental Kuznets curve (EKC) and propose alternative approaches that avoid these issues. Wagner notes that traditional methods do not take into account the presence of powers of unit root variables and cross-sectional dependence in the data while Vollebergh et al point out that the time effects are not uniquely identified in the EKC model. The between estimator is a simple estimator that also addresses the concerns of these authors. It makes no a priori assumption about the nature of the time effects and is likely to provide consistent estimates of long-run relationships in real world data situations. I apply several common panel data estimators including the between estimator to the datasets for carbon and sulfur emissions in the OECD and global sulfur emissions. The between estimates of the sulfur-income elasticity are 0.732 in the OECD and 1.067 in the global data set and the estimated carbon-income elasticity is 1.612 in the OECD and 1.509 globally.

Sulfur in plants: an ecological perspective

A book on sulfur research is highly justified at present as there has been, in the last decades, renewed research interest in S-biology in plants aimed at a better understanding of how plants adjust and cope with different sulfur availability. The biggest push has come from the increased incidence of sulfur deficiency in many areas of North Europe; something similar is happening around the whole of Europe now. Persistent sulfur impoverishment of soils, from Poland to Spain, from Italy to Finland, is combining with global climate changes to squeeze farmers. There is clear evidence linking these conditions to changes in soil sulfur content: essentially, the significant decrease in the input of sulfur from atmospheric deposition and the use of high-analysis low-sulfur fertilizers. Recent reports have shown that global sulfur emissions have declined at an annual rate of more than 2·7 %. Furthermore, today's molecular tools are far more sophisticated than any previous techniques, thus allowing unprecedented progress in study of the physiology, cell biology and molecular biology of sulfur. In this book, edited by two renowned experts in the field, the advances of the past decade are summarized and synthesized to elucidate the current state of knowledge of plant sulfur research. Twenty researchers who study plant sulphur nutrition have done an excellent job of discussing some of the most topical aspects in the plant-sulfur field in the context of plant ecology and physiology. The book consists of ten chapters and each one can be read in isolation. The chapters typically start with a very short introduction that raises a few important questions, which is followed by an extensive review of the relevant literature. The editors have chosen a style very similar to that of a review article, describing many experimental details of the corresponding original publications. Furthermore, chapters include comprehensive reference sections. We live in a scientific age and modern research and literature are very dynamic, so it is difficult to publish a book with the most recent references included. I am impressed that all the chapters include many papers published in 2006 and that more historic information is carefully selected with respect to relevance. Chapter 1 sets the scene with a short introduction covering a brief historical overview and gives some basic definitions. Chapter 2 provides an overview of various aspects of the adaptation of crop plants to changes in sulfur supply. Chapters 3 and 4 deal with the ecophysiological aspects of sulfur metabolism that contribute to the characterization of forest ecosystems and marine environments, respectively. Chapter 5 focuses on the impact of atmospheric sulfur gases on plants. The main focus of Chapter 6 is the presentation of comprehensive analyses using diverse ‘omic’ approaches, to improve our current understanding of sulfate metabolism and its integration into plant metabolism. Chapter 7 discusses the effect of sulfur on the capability of plants to cope with various oxidative stresses and on the efficiency of antioxidative defence systems. Chapter 8 dwells on the interrelations between metals and sulfur metabolism. The critical role of sulfur and sulfur compounds in plant responses to biotic stresses is discussed in Chapter 9 and, lastly, Chapter 10 provides valuable information on the physiological significance of selenium and its relationship with sulfur. In conclusion, this book provides the reader with a good overview of plant sulfur metabolism. The price is not low enough to be student-friendly, but taking into account the work that had to be done to collect the information relevant to this field, I would strongly recommend making the investment.

Strong sensitivity of late 21st century climate to projected changes in short‐lived air pollutants

This study examines the impact of projected changes (A1B “marker” scenario) in emissions of four short‐lived air pollutants (ozone, black carbon, organic carbon, and sulfate) on future climate. Through year 2030, simulated climate is only weakly dependent on the projected levels of short‐lived air pollutants, primarily the result of a near cancellation of their global net radiative forcing. However, by year 2100, the projected decrease in sulfate aerosol (driven by a 65% reduction in global sulfur dioxide emissions) and the projected increase in black carbon aerosol (driven by a 100% increase in its global emissions) contribute a significant portion of the simulated A1B surface air warming relative to the year 2000: 0.2°C (Southern Hemisphere), 0.4°C globally, 0.6°C (Northern Hemisphere), 1.5–3°C (wintertime Arctic), and 1.5–2°C (∼40% of the total) in the summertime United States. These projected changes are also responsible for a significant decrease in central United States late summer root zone soil water and precipitation. By year 2100, changes in short‐lived air pollutants produce a global average increase in radiative forcing of ∼1 W/m2; over east Asia it exceeds 5 W/m2. However, the resulting regional patterns of surface temperature warming do not follow the regional patterns of changes in short‐lived species emissions, tropospheric loadings, or radiative forcing (global pattern correlation coefficient of −0.172). Rather, the regional patterns of warming from short‐lived species are similar to the patterns for well‐mixed greenhouse gases (global pattern correlation coefficient of 0.8) with the strongest warming occurring over the summer continental United States, Mediterranean Sea, and southern Europe and over the winter Arctic.

Predicted change in global secondary organic aerosol concentrations in response to future climate, emissions, and land use change

The sensitivity of secondary organic aerosol (SOA) concentration to changes in climate and emissions is investigated using a coupled global atmosphere‐land model driven by the year 2100 IPCC A1B scenario predictions. The Community Atmosphere Model (CAM3) is updated with recent laboratory determined yields for SOA formation from monoterpene oxidation, isoprene photooxidation and aromatic photooxidation. Biogenic emissions of isoprene and monoterpenes are simulated interactively using the Model of Emissions of Gases and Aerosols (MEGAN2) within the Community Land Model (CLM3). The global mean SOA burden is predicted to increase by 36% in 2100, primarily the result of rising biogenic and anthropogenic emissions which independently increase the burden by 26% and 7%. The later includes enhanced biogenic SOA formation due to increased emissions of primary organic aerosol (5–25% increases in surface SOA concentrations in 2100). Climate change alone (via temperature, removal rates, and oxidative capacity) does not change the global mean SOA production, but the global burden increases by 6%. The global burden of anthropogenic SOA experiences proportionally more growth than biogenic SOA in 2100 from the net effect of climate and emissions (67% increase predicted). Projected anthropogenic land use change for 2100 (A2) is predicted to reduce the global SOA burden by 14%, largely the result of cropland expansion. South America is the largest global source region for SOA in the present day and 2100, but Asia experiences the largest relative growth in SOA production by 2100 because of the large predicted increases in Asian anthropogenic aromatic emissions. The projected decrease in global sulfur emissions implies that SOA will contribute a progressively larger fraction of the global aerosol burden.

Changes in atmospheric sulfur burdens and concentrations and resulting radiative forcings under IPCC SRES emission scenarios for 1990–2100

Simulations of the global sulfur cycle under the IPCC SRES scenarios have been performed. Sulfur dioxide and sulfate burdens, as well as the direct and first indirect radiative forcing (RF) by sulfate aerosols only, are presented for the period 1990 to 2100. By 2100, global sulfur emission rates decline everywhere in all scenarios. At that time, the anthropogenic sulfate burden ranges from 0.34 to 1.03 times the 1990 value of 0.47 Tg S. Direct and indirect global and annually mean RFs relative to the year 1990 are near 0 or positive (range of −0.07 to 0.28 Wm−2 and 0.01 to 0.38 Wm−2 for the direct and indirect effects, respectively). For reference these forcings amount respectively to −0.42 and −0.79 Wm−2 in 1990 relative to preindustrial conditions (around 1750). Sulfur aerosols will therefore induce a smaller cooling effect in 2100 than in 1990 relative to preindustrial conditions. For the period 1990 to 2100, the forcing efficiencies (computed relatively to 1990) are fairly constant for the direct effect (around −160 W (g sulfate)−1). The forcing efficiencies for the indirect effect are around −200 and −100 W (g sulfate)−1 for negative and positive burden differences, respectively. This is due to a shift in regional patterns of emissions and a saturation in the indirect effect. The simulated annually averaged SO2 concentrations for A1B scenario in 2020 are close to air quality objectives for public health in some parts of Africa and exceed these objectives in some parts of China and Korea. Moreover, sulfate deposition rates are estimated to increase by 200% from the present level in East and Southeast Asia. This shows that Asia may experience in the future sulfur‐related environmental and human health problems as important as Europe and the United States did in the 1970s.

Global sulfur emissions from 1850 to 2000

The ASL database provides continuous time-series of sulfur emissions for most countries in the World from 1850 to 1990, but academic and official estimates for the 1990s either do not cover all years or countries. This paper develops continuous time series of sulfur emissions by country for the period 1850–2000 with a particular focus on developments in the 1990s. Global estimates for 1996–2000 are the first that are based on actual observed data. Raw estimates are obtained in two ways. For countries and years with existing published data I compile and integrate that data. Previously published data covers the majority of emissions and almost all countries have published emissions for at least 1995. For the remaining countries and for missing years for countries with some published data, I interpolate or extrapolate estimates using either an econometric emissions frontier model, an environmental Kuznets curve model, or a simple extrapolation, depending on the availability of data. Finally, I discuss the main movements in global and regional emissions in the 1990s and earlier decades and compare the results to other studies. Global emissions peaked in 1989 and declined rapidly thereafter. The locus of emissions shifted towards East and South Asia, but even this region peaked in 1996. My estimates for the 1990s show a much more rapid decline than other global studies, reflecting the view that technological progress in reducing sulfur based pollution has been rapid and is beginning to diffuse worldwide.

Explaining changes in global sulfur emissions: an econometric decomposition approach

Changes in the emission of anthropogenic pollutants can be attributed to changes in input mix, output mix, scale, and the state of technical progress. I develop a non-linear emissions decomposition model and apply it to a panel data set for sulfur emissions in 64 countries from 1973 to 1990. The results show that though input and output mix are statistically significant and important in explaining emissions in individual countries, they make only a small contribution to changes in global emissions. Increasing scale and countervailing technical change explain most of the observed global change. I also estimate an environmental Kuznets curve model for the same dataset, which yields a monotonic emissions-income relation at the global level. This model does not explain as much variance as the decomposition model and has poorer statistical properties. A nested test of the two models shows that the EKC imposes significant restrictions on the general model, while the decomposition model does not.

The annual volcanic gas input into the atmosphere, in particular into the stratosphere: a global data set for the past 100 years

We compiled a global data set of volcanic degassing during both explosive and quiescent volcanic events. The data set comprises estimates of gas emissions of volcanoes from Europe (e.g. Etna), Asia (e.g. Merapi), the Americas (e.g. Fuego), Africa (e.g. Erta Ale) and ocean islands (e.g. Kilauea) over the past 100 yr. The set includes 50 monitored volcanoes and ∼310 extrapolated explosively erupting volcanoes. Among the ∼360 volcanoes, 75% are located in the Northern and 25% in the Southern Hemisphere. We have estimated the total annual global volcanic sulfur emission into the atmosphere to be on the order of 7.5–10.5×1012 g/yr S (here as SO2), amounting to 10–15% of the annual anthropogenic sulfur output (∼70×1012 g/yr S during the decade 1981–1990) and 7.5–10.5% of the total global sulfur emission (e.g. biomass burning, anthropogenic, dimethylsulfide) with ∼100×1012 g/yr S. The estimates of other volcanic gases emitted (e.g. H2S, HCl) are based on the assumption that the different gas components emitted by a volcano are in equilibrium with each other. Accordingly, the molar ratios of the gas species in high-temperature fumaroles are similar to molar ratios equilibrated at depth where the gas separates from the magma. Thus, we can use the directly measured SO2 fluxes and known molar ratios (e.g. H2S/SO2) for a semi-quantitative estimate of other gas components emitted (e.g. H2S). The total annual emission of HCl is 1.2–170×1012 g/yr, that of H2S 1.5–37.1×1012 g/yr, of HF 0.7–8.6×1012 g/yr, of HBr 2.6–43.2×109 g/yr, and of OCS 9.4×107–3.2×1011 g/yr. We estimate an emission of 1.3×107–4.4×1010 g/yr for CS2.

Global and regional anthropogenic sulfur dioxide emissions

We present a new inventory of global sulfur dioxide emissions from anthropogenic activities for the years 1980–2000. Emissions were estimated in 11 world regions using country-level emissions inventories and regional fossil fuel sulfur content information. Estimated global emissions in 1990 are 72 TgS with an estimated uncertainty of ±8% due to random errors with additional systematic errors that suggest that true emissions may be higher than this central value. We estimate that 56% of 1990 world emissions are from coal, 24% from oil, 15% from industrial processes and 3% from biomass burning. When our results are compared with other studies, they are similar at the global-mean level, but show marked differences at the regional level. Globally, emissions have been roughly constant from 1980 to the present. However, a significant shift has occurred in the spatial distribution of emissions. While 60% of global emissions in 1980 were from around the North Atlantic basin, this region contributed less than 40% of the global total by 1995 and will contribute even less in the future. Currently, based on our estimates, the centrally planned Asia (CPA) region, dominated by China, is the largest contributor to global sulfur dioxide emissions. A gridded data set for 1990 emissions is also produced, including a consistent seasonal cycle and a stratification of emissions into low and elevated releases. Implications for climate modeling and detection studies are discussed.

Estimating historical anthropogenic global sulfur emission patterns for the period 1850–1990

It is important to establish a reliable regional emission inventory of sulfur as a function of time when assessing the possible effects of global change and acid rain. This study developed a database of annual estimates of national sulfur emissions from 1850 to 1990. A common methodology was applied across all years and countries allowing for global totals to be produced by adding estimates from all countries. The consistent approach facilitates the modification of the database and the observation of changes at national, regional, or global levels. The emission estimates were based on net production (i.e., production plus imports minus exports), sulfur content, and sulfur retention for each country's production activities. Because the emission estimates were based on the above considerations, our database offers an opportunity to independently compare our results with those estimates based on individual country estimates. Fine temporal resolution clearly shows emission changes associated with specific historical events (e.g., wars, depressions, etc.) on a regional, national, or global basis. The spatial pattern of emissions shows that the US, the USSR, and China were the main sulfur emitters (i.e., approximately 50% of the total) in the world in 1990. The USSR and the US appear to have stabilized their sulfur emissions over the past 20 yr, and the recent increases in global sulfur emissions are linked to the rapid increases in emissions from China. Sulfur emissions have been reduced in some cases by switching from high- to low-sulfur coals. Flue gas desulfurization (FGD) has apparently made important contributions to emission reductions in only a few countries, such as Germany.

Global sulfur emissions inventories for oceangoing ships and their impact in global chemical transport models

Global sulfur emissions inventories for oceangoing ships and their impact in global chemical transport models