Anthropogenic Sulfur Emissions Research Articles

Effects of anthropogenic sulfate on cloud drop nucleation and optical properties

The characteristics of the cloud drop size distribution near cloud base are initially determined by the aerosol particles that serve as cloud condensation nuclei (CCN) and the updraft velocity. Changes in CCN concentrations can change cloud drop number thereby affecting cloud optical properties and the global radiation budget. The CCN concentration depends on the composition and size distribution of the aerosol particles. Chemical reactions of the emitted gaseous sulfur compounds due to human activities will alter, through gas-to-particle conversion, the aerosol size distribution, total number, and its chemical composition. It is important to assess these changes in order to estimate the effect of anthropogenic sulfur emissions on cloud drop number concentrations. Here, we assume that the aerosol size distribution is modified, with total number unchanged, by two processes: condensation of sulfuric acid vapor (H 2 SO 4 ) on a prescribed pre-existing particle size distribution and aqueous-phase oxidation of SO 2 followed by evaporation of the drops. We examine the relationship between the resulting anthropogenic sulfate-containing aerosol size distribution and cloud drop number concentrations. The results are used to estimate the possible change in cloud optical thickness and cloud albedo due to an increase of anthropogenic sulfate mass concentration. This work is aimed at improving the assessment of the effects of anthropogenic sulfate on cloud optical properties and the global radiation budget. DOI: 10.1034/j.1600-0889.47.issue5.4.x

Effects of anthropogenic sulfate on cloud drop nucleation and optical properties

The characteristics of the cloud drop size distribution near cloud base are initially determined by the aerosol particles that serve as cloud condensation nuclei (CCN) and the updraft velocity. Changes in CCN concentrations can change cloud drop number thereby affecting cloud optical properties and the global radiation budget. The CCN concentration depends on the composition and size distribution of the aerosol particles. Chemical reactions of the emitted gaseous sulfur compounds due to human activities will alter, through gas-to-particle conversion, the aerosol size distribution, total number, and its chemical composition. It is important to assess these changes in order to estimate the effect of anthropogenic sulfur emissions on cloud drop number concentrations. Here, we assume that the aerosol size distribution is modified, with total number unchanged, by two processes: condensation of sulfuric acid vapor (H 2 SO 4 ) on a prescribed pre-existing particle size distribution and aqueous-phase oxidation of SO 2 followed by evaporation of the drops. We examine the relationship between the resulting anthropogenic sulfate-containing aerosol size distribution and cloud drop number concentrations. The results are used to estimate the possible change in cloud optical thickness and cloud albedo due to an increase of anthropogenic sulfate mass concentration. This work is aimed at improving the assessment of the effects of anthropogenic sulfate on cloud optical properties and the global radiation budget. DOI: 10.1034/j.1600-0889.47.issue5.4.x

Assessment of wet sulphur deposition over the former USSR

The data obtained by different national and international networks of precipitation chemistry monitoring the territory of the former Soviet Union (FSU) have been generalized. Analyses of long-term trends of sulphur concentrations in precipitation for a 30-year period showed that the changes did not correlate with the dynamics of anthropogenic sulphur emissions into the atmosphere both over the FSU territory and Europe as a whole. Sulphur concentrations in precipitation reveal an obvious seasonal dependence with the spring maximum while deposition intensity has its maximum during summer time. All the FSU territory has been divided into 20 regions, and the mean values of sulphur concentration in precipitation and wet deposition have been estimated for each of them. The highest values were characteristic of the south-western part of the country and lowest ones of the remote areas of NorthEast. In the 80s, about 6.0 Tg of sulphur were annually wet deposited over the European territory of the FSU, about 3.0 Tg over the territory of Kazahstan and Central Asia, about 5.7 Tg in Siberia and the Russian Far East. The total wet sulphur deposition made up 60–90% of the anthropogenic sulphur emissions into the FSU atmosphere. DOI: 10.1034/j.1600-0889.1994.t01-2-00004.x

A comparison between patterns of temperature trends and sulfate aerosol pollution

Global temperature records over the past century are compared to estimated atmospheric loading of anthropogenic aerosol sulfate, in order to investigate the possible cooling effect of such pollutants. Between the 1940s and the 1980s south‐eastern Europe, China, and the northern Atlantic have experienced a summertime cooling. The first two of these regions agree well with those where anthropogenic sulfur emissions have increased during the same period. During winter, the two former regions experienced a substantial warming while the northern Atlantic and south‐eastern US exhibited a cooling. The results are qualitatively consistent with theoretical calculations which indicate that anthropogenic sulfate aerosols cause a substantial cooling. However, because of large natural variations in the temperature records, the statistical significance of this conclusion is low.

Natural sulfur emissions to the atmosphere of the continental United States

Seasonal emissions of biogenic sulfur gases from marine and terrestrial sources were assessed for 13 regions of the continental United States. The resulting inventory was compared to volcanic and anthropogenic sulfur emissions from the same regions. Terrestrial biogenic sulfur emissions were less than 1% of the total sulfur emissions in each region. However, during the summer, marine biogenic sulfur emissions may be contributing 20–40% of the total sulfur emissions in western coastal regions.

Anthropogenic influence on the distribution of tropospheric sulphate aerosol

HUMAN activities have increased global emissions of sulphur gases by about a factor of three during the past century, leading to increased sulphate aerosol concentrations, mainly in the Northern Hemisphere. Sulphate aerosols can affect the climate directly, by increasing the backscattering of solar radiation in cloud-free air, and indirectly, by providing additional cloud condensation nuclei1–4. Here we use a global transport–chemistry model to estimate the changes in the distribution of tropospheric sulphate aerosol and deposition of non-seasalt sulphur that have occurred since pre-industrial times. The increase in sulphate aerosol concentration is small over the Southern Hemisphere oceans, but reaches a factor of 100 over northern Europe in winter. Our calculations indicate, however, that at most 6% of the anthropogenic sulphur emissions is available for the formation of new aerosol particles. This is because about one-half of the sulphur dioxide is deposited on the Earth's surface, and most of the remainder is oxidized in cloud droplets so that the sulphate becomes associated with pre-existing particles. Even so, the rate of formation of new sulphate particles may have doubled since pre-industrial times.

SULFUR: THE PLANKTON/CLIMATE CONNECTION

Question (Aiken et al.): Given the uncertainties involved in the calculation of air-sea exchange of gases such as DMS, is it possible to assess by other methods the importance of natural versus anthropogenic sulfur emissions? Answer: In our paper we discuss various approaches that have been taken to estimate the rate of emission of DMS from the oceans including models (Erikson et al. 1990, Thompson et al. 1990) and the use of observed concentration fields of DMS combined with knowledge of air-sea transfer velocity (Andreae 1986, Bates et al. 1987b). In addition measurements of MSA in atmospheric aerosols can be used to infer the emission of DMS into the atmosphere (J. Prospero, University of Miami, pers. commun.). Many studies (not reviewed in this paper) have investigated the emissions of sulfur from manmade sources. In all these attempts, an assessment is often made of the relative importance of the two sources, although the methodology used to calculate biogenic and anthropogenic sources are fundamentally different. The only consistent approach we are aware of, which has the potential to directly ascribe sulfur in the atmosphere to its major sources, is through the use of sulfur isotope signature measurements. The method relies on the sulfur isotope signature of fossil fuels being significantly different from that of DMS and its oxidation products. This approach shows great promise and is currently being investigated in our laboratory.

The influence of north American anthropogenic sulphur emissions over western Europe

The influence of north American anthropogenic sulphur emissions over western Europe

Sulfur emissions to the atmosphere from natural sourees

Emissions of sulfur gases from both natural and anthropogenic sources strongly influence the chemistry of the atmosphere. To assess the relative importance of these sources we have combined the measurements of sulfur gases and fluxes during the past decade to create a global emission inventory. The inventory, which is divided into 12 latitude belts, takes into account the seasonal dependence of sulfur emissions from biogenic sources. The total emissions of sulfur gases from natural sources are approximately 0.79 Tmol S/a. These emissions are 16% of the total sulfur emissions in the Northern Hemisphere and 58% in the Southern Hemisphere. The inventory clearly shows the impact of anthropogenic sulfur emissions in the region between 35° and 50°N.

人為起源の硫黄酸化物による地球規模的な環境影響について

On global environment impact by acid precipitation, this paper projected anthropogenic sulfur dioxide emission by the end of next century, and discussed on its environmental effects. Comprehensive global environmental model, now we are developing, was applied in order to give quantitative aspects of the analysis. The amount of anthropogenic sulfur emission is ranged from 59TgS/y to 800TgS/y by the end of next century, corresponding to the prescribed social and economical scenarios. Land area where 22%-40% of total world people live is influenced from the view point of soil alkalinity depression. Population and economic growth variations, degree of eagerness of energy efficiency improvement as well as the direct effort on emission reduction greatly influence on the future global environment.

The influence of north American anthropogenic sulphur emissions over western Europe

3-dimensional Eulerian model is used to evaluate the influence of North American anthropogenic sulphur emissions over the western coast of Europe. Transport of sulphur across the North Atlantic ocean is simulated on the basis of the actual meteorology for 4 different months during 1982 and 1983. Results show large regional variations and indicate that the relative importance of North American emissions is largest over north western Europe. The North American contribution to pollution levels over western Europe is shown to occur mainly as wet deposition. Maximum wet deposition of North American origin over north western Europe is predicted for January 1983. On average over the four simulated months, the wet deposition of North American origin is estimated to be 2 mg S m-2 month-1 which represents 10% of the calculated total deposition over western Europe. The influence of North American sulphur on the air concentrations over the west coast of Europe is relatively larger at higher levels in the atmosphere. At ground level, the North American contribution to sulphate in air represents only 2.5% of the averaged total calculated, but it ascends to 50% at 5000 m. Maximum contributions to the sulphate concentrations in air over western Europe are estimated to occur during July 1983.

Hints of another gremlin in the greenhouse: anthropogenic sulfur

Already there are many complicating factors (‘gremlins’) that frustrate attempts to link observed climate changes to predictions from the greenhouse hypothesis. Consequences of these ‘gremlins in the greenhouse’ (along with their possible identities) include hemispherically asymmetric cooling of the lower stratosphere (perhaps caused by asymmetric ozone destruction by chlorofluorocarbons), cooling of the tropical upper troposphere (perhaps caused by an increase in water vapor), lack of polar amplification of lower tropospheric warming (poorly modeled clouds, ocean currents, ice and snow et al.), and asymmetric warming of the lower tropospheres of the two hemispheres (differences in thermal inertias, responses to volcanic eruptions et al.). In this report, emphasis is on examining hints that the cause of the relative cooling of the Northern Hemisphere has been anthropogenic sulfur emission; it is concluded that this concept is not inconsistent with the data; however, the possibility that all observed temperature changes are natural is also not inconsistent with the data. Research needed to remove these ambiguities includes more extensive monitoring, improvements to climate models, advances in statistical analyses of time series, better definition of climatic consequences of volcanic eruptions, and focused efforts to understand and describe the major climate changes that occurred in the Northern Hemisphere c. 1940 and 1815.

Rainwater composition at two BAPMoN regional stations in SE Australia

Analysis of 5 years of rainwater composition data from two BAPMoN Regional stations in southeastern Australia shows both sites to be relatively little influenced by anthropogenic sulfur and nitrogen emissions. Long-term average depositions of non-sea-salt (nss) sulfate, nitrate and ammonium were all 5, though it must be acknowledged that the sampling protocols used in the BAPMoN network are such that weak organic acids will be lost from the samples prior to analysis. No secular trends in ion concentration or deposition were discernible over the 5-year data record for any of the species determined. DOI: 10.1034/j.1600-0889.1991.t01-4-00004.x

Cloud condensation nuclei over the Southern Ocean

The basis of a cloud condensation nucleus (CCN) climatology program has been in place at Cape Grim (Tasmania) since 1982. This has shown both marked seasonal variation and evidence of interannual variation in CCN concentration. CCN concentrations have been found to be substantially understandable in terms of the condensation or Aitken nucleus (CN) concentration and size. Whether CCN concentrations are systematically changing in response to climate change and/or increasing anthropogenic sulfur emission is an unresolved question. Although present CCN concentrations are higher than those reported for clean oceanic regions two decades earlier, the data do not allow confident conclusions about the cause.

Acid rain, a world‐wide phenomenon: a perspective from the united states

The observation that precipitation carries particles and gases to the earth's surface has been a recurrent interest of scientists for more than two hundred years. Since the late 1940s, this interest has been piqued by the observation that rainfall is acidic, and that this acidity results largely from the byproducts of combustion. “Acid rain” occurs over large areas of Europe and North America. Using recent data from a large United States network of collection stations, we show maps of pH, sulfate, nitrate, ammonium, and calcium in precipitation; we also show the results of an analysis of trends in these ions from 1979 to 1986. Sulfate, nitrate, and hydrogen ion concentrations peak in the northeastern United States where anthropogenic emissions of sulfur and nitrogen are highest. Ammonium and calcium ions peak in the central part of the United States, where the combination of biogenic, surficial and anthropogenic sources of these pollutants is highest. Though only calcium trends were statistically signific...