Source of sulfate

Several types of chemical processes are used to produce potassium sulfate. The traditional Mannheim process is used in countries that produce KCl but lack a natural source of sulfate salts for converting the KCl to K2SO4. In this process, KCl reacts with sulfuric acid to yield K2SO4 and HCl as a co-product. 

In contrast to sodium chloride, langbeinite has an extremely slow rate of solution. Upon control of agitation time, essentially all the sodium chloride dissolves but most of the langbeinite remains as a soHd. Langbeinite is separated from the brine, dried, and then screened into granular, standard, and special-standard particle sizes. These fractions are marketed directiy. In one plant, the unsalable fines are used as the source of sulfate reactant for the production of potassium sulfate. 

The efficiency of the weathering of rocks in using carbonic acid produced in the carbon cycle is affected by various hydrologic, environmental, and cultural controls. The fact that the principal anion in fresh surface water worldwide almost always is bicarbonate attests to the overriding importance of this process. Exceptions are systems in which evaporite minerals are available for dissolution by groundwater or where human activities are major sources of sulfate or chloride inflow. 

Geochemical studies of sulfate ia streams have beea approached ia various ways. For example. Ref. 17 is a review of Hterature oa sources of sulfate ia the dissolved loads of streams, especially ia areas where developmeat effects are likely to be stroag. It was coacluded that for North America as much as 60% of the average yield of sulfate carried to the ocean is related to human activities. This study assigned a higher proportion of the total yield of sulfate ia European streams to human sources, but for other continents it was thought the effects of human activities to be relatively minor. 

Figures 33.3-33.4 show the results at the end of the simulation, after groundwater composition and microbial activity across the aquifer have approached steady state. Once the sulfate initially present is consumed or flushed from the aquifer, the only source of sulfate is in the recharging groundwater. With time in the simulation, sulfate reducing bacteria grow into a community that consumes sulfate from the recharging groundwater and some of the acetate diffusing into the aquifer the acetate and sulfate are consumed in equal molar proportions, according to Reac-...

Cockerton, S. 2008a. Experimental constraints for the source of sulfate toxicity and predictive water quality for the Hogarth and Caland pit lakes, Steep Rock Iron Mine, Northwestern Ontario, Canada. Mine Water and the Environment Proceedings, 10, 551-554. 

The data indicate that Mono Lake has the potential to become a significant source of sulfate aerosols if the lake bed areas are exposed. 

Dimethyl sulfide is believed to be a significant source of sulfate in the marine boundary layer via its oxidation by OH, N03, and Cl. Compare the lifetimes for rates of oxidation of DMS by these three species, assuming peak concentrations of OH of 1 X 107 radicals cm"3, NO-, = 10 ppt, and Cl = 1 X 105 atoms cm"3. (However, note that these oxidants peak at different times of the day see Problem 12.)... 

The source of sulfate may be dietary or generated by oxidative metabolism of cysteine. PAPS can become depleted when large amounts of a foreign compound conjugated with sulfate, such as paracetamol, are administered. 

Possible sources of sulfate include diffusion from the water column, hydrolysis of sulfate esters, and oxidation of reduced sulfur. Diffusion of S042" into sediments cannot supply sulfate at the measured rates of sulfate reduction. Rates of sulfate diffusion into sediments generally are 2 orders of... 

In the first paper, Wolff and his colleagues (16) describe the measurements of gas and particulate species found in the Lewes samples and the composition and sources of sulfate aerosol. On the average, the total-suspended-particulate (TSP) concentration at Lewes is 27.9 pg/m3 while the PM10 (mass of particles with diameters 10 im) concentration is 22.0 pg/m, or 79% of the TSP. The PM10 consists of 6.1 pg/m3 of coarse particles (CPM, diameters = 2.5 pm to 10 pm) and 15.9 pg/m of fine particles (FOM, diameters <... 

The major source of sulfate aerosols appears to be the oxidation of atmospheric I S and S02. While some is also produced by sea spray, most of the sea-salt aerosol returns directly to the ocean, resulting in only a small net production. 

Leung, Colussi and Hoffmann have used isotopic analysis in an attempt to constrain the amount of sulfate that could be produced by Crutzen s mechanism [129,130]. The first study retrieved the concentration profiles of OC S and OC S from infrared transmission spectra of the atmosphere recorded by the NASA MkIV balloon-borne interferometer. They derived an enrichment factor of 73.8 zb 8.67oo defined such that photolytically generated sulfur would be enriched in An isotopic budget based on this result shows that OCS photolysis cannot be a significant source of sulfate aerosol, since the enrichments of OCS, sulfuric acid aerosol and SO2 are known to be small [131]. A later laboratory study by the same group came to the conclusion that stratospheric photolysis results in an enrichment of 67 zb 77oo. 

Research Station (12,500 ft) there is a significant upper atmospheric source of sulfate. Johnson et al. (2001) have used the 5 0 measurements to provide new insight into surface water interactions and sources in a high alpine region of the Rocky Mountains. 

Intensive investigations of the sulfur dynamics of forest ecosystems in the last decade can be attributed to the dominant role of sulfur as a component of acidic deposition. Studies in forested catchments include Fuller et al. (1986), Mitchell et al. (1989), Stam et al. (1992), and Andersson et al. (1992). Sulfur with a distinctive isotopic composition has been used to identify pollution sources (Krouse et al., 1984), and has been added as a tracer (Legge and Krouse, 1992 Mayer et al., 1992, 1993). Differences in the natural abundances can also be used in systems where there is sufhcient variation in the 5 " S of ecosystem components. Rocky Mountain lakes (USA), thought to be dominated by atmospheric sources of sulfate, have different 5 " S values than lakes believed to be dominated by watershed sources of sulfate (Turk et al., 1993). 

The principal sources of sulfate in formation waters are dissolved marine sulfate, sulfate derived from the dissolution of evaporites, and sulfate formed by the oxidation of sulfides. Sulfate is destroyed by reduction to hydrogen sulfide. The value of 5 " S in gypsum is only — 1.6%o heavier than sulfate in solutions from which it precipitates. The isotopic composition of sulfur in gypsum in Phanerozoic deposits precipitated from seawater during evaporation thus tracks the secular changes in the isotopic composition of sulfur in seawater ( 10% to 30%o). 

Other sources of sulfate in crystalline environments have been documented to be magmatic or hydrothermal (Hattori and Cameron, 1986 Hattori, 1989). Such sulfates have positive 5 " S... 

Other evidence for low Archean atmospheric oxygen concentrations come from studies of mass-independent sulfur isotope fractionation. Photochemical oxidation of volcanic sulfur species, in contrast with aqueous-phase oxidation and dissolution that characterizes the modem sulfur cycle, may have been the major source of sulfate to seawater in the Archean (Farquhar et al., 2002 Farquhar et al., 2000). Distinct shifts in and in sulfide and sulfate from... 

The discovery of substantial amounts of volatile organosulfides in the oceans was one of the major additions to the sulfur cycle in the second half of the twentieth century. The largest flux of reduced sulfur to the atmosphere from the oceans is as DMS. The importance of this compound that was largely unknown in nature until the 1970s was revealed by Lovelock et al. (1972) as a potential explanation for the imbalance in the sulfur cycle. Over time it has become clear that this process has important implications to the atmosphere and offers a source of sulfate to form cloud condensation nuclei. 

Cravotta C. A., Ill (1994) Secondary iron sulfate minerals as sources of sulfate and acidity-the geochemical evolution of acidic ground water at a reclaimed surface coal mine in Pennsylvania. In Environmental Geochemsitry of Sulfide Oxidation (eds. C. N. Alpers and D. W. Blowes). American Chemical Society, Washington, DC, vol. 550, pp. 345-364. 

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