Global anthropogenic sulfur emissions

FIGURE 2.1 Estimated global anthropogenic sulfur emissions. The range of global natural sulfur emissions (excluding seasalt) is indicated. [Adapted from Lefohn et al. (1999).]... 

Hemisphere. Figure 2.1 shows estimates of global anthropogenic sulfur emissions since 1850, and Table 2.3 summarizes observed mixing ratios and atmospheric lifetimes of atmospheric sulfur gases. 

Figure 5.4.1 Global anthropogenic sulfur emissions (as SO2) from 1850 to 2000 [data from Stern (2005)].

The results of a global 3-dimensional model simulation also suggest that in the boundaiy layer in the United States, a 50% reduction in anthropogenic S02 emissions in the United States will result in a similar (53%) annual reduction in the total (wet plus dry) deposition of sulfur (Chin and Jacob, 1996). 

On a global scale, natural emissions of reduced sulfur compounds account for about 50% of the total sulfur flux into the atmosphere (1-3). Hence, it is important to understand the natural sulfur cycle in order to establish a "base line" for assessing the significance of anthropogenic perturbations (primarily SO2 emissions). Dimethylsul-fide (DMS) is the predominant reduced sulfur compound entering the atmosphere from the oceans (4-9), and DMS oxidation represents a major global source of S(VI). The atmospheric oxidation of DMS can be initiated by reaction with either OH or NO3. In marine environments, however, NO3 levels are typically very low and DMS is destroyed primarily by OH ... 

Table 10-17 includes a global atmospheric sulfur budget based on the emission estimates discussed in this chapter and the flux diagrams shown in Figs. 10-8 and 10-9. The marine budget of 36 Tg S/yr supplied by the biosphere must be augmented by about 6.8 Tg S/yr from anthropogenic sources. In addition, about one-half of the sulfur from volcanic emissions... 

Table 2.2 presents estimates of total sulfur emissions to the atmosphere, both anthropogenic and natural, including estimated division between Northern and Southern Hemispheres. Current estimates place total global emissions (excluding seasalt) in the range of 98-120 Tg(S)yr -1. At present, anthropogenic emissions account for about 75% of total sulfur emissions, and 90% of the anthropogenic emissions occur in the Northern... 

Lefohn, A. S., Husar, J. D., and Husar, R. B. (1999) Estimating historical anthropogenic global sulfur emission patterns for the period 1850-1990, Atmos. Environ. 33, 3435-3444. 

Natural and anthropogenic sulfur aerosols play a major role in atmospheric chemistry and potentially in modulating global climate. One theory holds that a negative feedback links the emission of volatile organic sulfur (mostly as DMS) from the ocean with the formation of cloud condensation nuclei, thereby... 

Smith, S. (2001) Global and regional anthropogenic sulfur dioxide emissions. Global and Planetary Change 29, 99-119... 

Varhelyi, G. (1985) Continental and global sulfur budgets-I. Anthropogenic SO2 emissions. 

Particle precursor gases are emitted into the atmosphere either directly by natural and anthropogenic sources or by oxidation processes in the atmosphere. The most prominent precursor gas is probably sulfur dioxide (SO2). It is the precursor for particulate sulfates, such as sulfuric acid (H2SO4) or ammonium sulfate [(NH4)2S04]. Sulfur dioxide is directly emitted by natural sources (e.g., volcano emptions). Anthropogenic sources in industrial regions are mostly associated with combustion processes (e.g., coal combustion). Additional SO2 is derived from oxidation processes of dimethyl sulfide (DMS) over the oceans. Estimations of the global sulfur emissions from these sources are listed in Table 3. 

Little snlfnr is re-emitted from wetlands into the atmosphere. Table 8.7 gives estimates of global emissions of volatile sulfur compounds from different sources. Total emissions are in the range 98 to 120 Tg (S) year 75 % is anthropogenic, mainly from fossil fnel combustion in the northern hemisphere. The main natural sources are the oceans and volcanoes. Wetlands and soils contribnte less than 3 % of the total emission. 

The global natural flux of sulfur compounds to the atmosphere has recently been estimated to be about 2.5 Tmol yr1 (1) which is comparable to the emissions of sulfur dioxide (SO2) from anthropogenic sources (2). A substantial amount of the natural sulfur contribution (0.5-1.2 Tmol yr1) is attributed to the emission of dimethylsulfide (DMS) from the world s oceans to the atmosphere (3.4). One of the major uncertainties in this estimate is due to a scarcity of DMS and other sulfur data from the Southern Hemisphere, particularly the Southern Ocean region between about 40°S and the Antarctic continent, which represents about one fifth of the total world ocean area. 

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