Airborne sulfur compounds

Acid aerosol, description, 58 Acidification effects of airborne sulfur compounds, 62-63,64/... 

Airborne sulfur compounds acidification effects, 62-63,64/ atmospheric visibility effects, 63,65 human health effects, 61-62 materials degradation effects, 62 w-Alkanes, predominance of even-number compounds, 435,438,435/440 n-Alkyl monocyclic sulfides, structures,... 

Lead-stabilized products, used in some parts of the world in rigid extrusions, often contain 0.4-0.8 phr of calcium stearate as internal lubricant, 0.2-0.5 phr of stearyl alcohol to improve the mobility of the stabilizer (normally dibasic lead phosphate or combinations with tribasic lead sulfate), and 0.4-0.75 phr of partly saponified mon-tanic ester as a multifunctional lubricant. For the ultimate in process stability, calcium stearate may be replaced by a barium/cadmium stearate blend. The inclusion of cadmium also reduces the severity of staining by airborne sulfur compounds. Although lead-stabilized rigid compounds offer advantages in material cost and process safety, their use should be abandoned because of the hazard involved and because such usage is prejudicial to acceptance of vinyl products. 

In the case of these two regions there is a natural source of airborne salinity the waters of the Atlantic Ocean, the Gulf of Mexico and the Caribbean Sea. Airborne salinity plays an important role in determining corrosion aggressivity in Cuba [1-4] and in the Yucatan Peninsula [2, 5-6], Other anthropogenic contaminants can be present also in this region, particularly sulfur compounds coming from the oil production and manufacture industries and... 

Because the FPD responds to both aerosol and gaseous sulfur species, it has also been possible to modify these instruments to continuously measure aerosol sulfur by selectively removing gaseous sulfur compounds with a lead(II) oxide-glycerol coated denuder (55). Use of such an instrument for airborne measurements of aerosol sulfur in and around broken clouds has been reported (57). In principle, speciation between aerosol sulfate, disulfate, and sulfuric acid by selective thermal decomposition (58, 59) can also be achieved. Flame photometric detectors have also been used as selective detectors for gas chromatography. Thornton and Bandy (60) reported the use of a chromatographic system with a flame photometric detector for airborne measurement of S02 and OCS with a detection limit of 25 pptrv. 

Deposition of airborne compounds derived from volcanic eruptions, and the presence of sulfur compounds brought about through hydrothermal activity (i.e., hot springs). 

Poisoning of the catalyst by contaminants in the fuel/air mixture is one of the major factors affecting catalyst lifetime. Sulfur compounds in the natural gas fuel are possible catalyst poisons. Dust or other contaminants in the air ingested by the turbine could be deposited on the catalyst and mask the active sites or could react with and deactivate the catalyst. In coastal areas salt from sea air is a potential catalyst poison. The catalyst should be sufficiently resistant to these airborne contaminants so that performance is maintained for at least one year. 

Combustion of coal and other fossil fuels is the primary source of airborne selenium compounds. In air, elemental selenium burns to form selenium dioxide however, during the combustion of fossil fuels, essentially all of the selenium dioxide produced should be reduced to elemental selenium by the sulfur dioxide that results from the combustion of these materials (NAS 1976a). Estimates of the quantity of selenium released to the air from fossil fuel combustion vary. Estimated annual selenium air emissions from stationary sources in the United States for 1969-1971,1978, and 1983 were 900,1,240, and 1,560 tons selenium/year, respectively (EPA 1974 Lee and Duffield 1979). Dulka and Risby (1976) estimated yearly releases of selenium to the air from fossil fuel combustion to be 1,000 tons. Harr (1978)... 

Eutrophication and Acidification Eutrophication potential comprise airborne and waterborne emissions of nitrogen and phosphor compounds that promote excessive plant growth (Fig. 13.27). Acidification potential takes into account emissions of some nitrogen and sulfur compounds, hydrogen fluoride, and other... 

Industrial environments contain sulfur compounds, nitrogen compounds, and other acidic agents that can promote the corrosion of steels. In addition, industrial environments contain a heavier loading of airborne particles, which also contribute to corrosion. Urban environments are comparable with industrial, but the amount of pollution will be less intense. Marine environments are characterized by the presence of chloride, an ion that is particularly detrimental to the corrosion resistance of steels. Rural and indoor environments are the least corrosive of the atmospheric environments. 

Environmental protection to seal out moisture and other airborne contaminants, especially salts and sulfur compounds... 

Effects of Sulfur Compounds on Materials, Including Historical and Cultural Monuments, in Airborne Sulfur Pollution Effects and Control," United Nations, New York, 1984. 

Thiuram Sulfides. These compounds, (8) and (9), are an important class of accelerator. Thiurams are produced by the oxidation of sodium dithiocarbamates. The di- and polysulfides can donate one or more atoms of sulfur from their molecular stmcture for vulcanization. The use of these compounds at relatively high levels with litde or no elemental sulfur provides articles with improved heat resistance. The short-chain (methyl and ethyl) thiurams and dithiocarbamates ate priced 2/kg. Producers have introduced ultra-accelerators based on longer-chain and branched-chain amines that are less volatile and less toxic. This development is also motivated by a desire to rninirnize airborne nitrosamines. 

The chemical composition of particulate pollutants is determined in two forms specific elements, or specific compounds or ions. Knowledge of their chemical composition is useful in determining the sources of airborne particles and in understanding the fate of particles in the atmosphere. Elemental analysis yields results in terms of the individual elements present in a sample such as a given quantity of sulfur, S. From elemental analysis techniques we do not obtain direct information about the chemical form of S in a sample such as sulfate (SO/ ) or sulfide. Two nondestructive techniques used for direct elemental analysis of particulate samples are X-ray fluorescence spectroscopy (XRF) and neutron activation analysis (NAA). 

The toxicity characteristic leaching procedure may be subject to misinterpretation if the compounds under investigation are not included in the methods development or the list of contaminants leading to the potential for technically invalid results. However, an alternative procedure, the synthetic precipitation leaching procedure (SPLP, EPA SW-846 Method 1312) may be appropriate. This procedure is applicable for materials where the leaching potential due to normal rainfall is to be determined. Instead of the leachate simulating acetic acid mixture, nitric and sulfuric acids are utilized in an effort to simulate the acid rains resulting from airborne nitric and sulfuric oxides. 

Becker, G., Nilsson, U., Cohnsjo, A., and Ostman, C., Determination of polycyclic aromatic sulfur heterocyclic compounds in airborne particulate by gas chromatography with atomic emission and mass spectrometric detection, J. Chromatogr. A, 825, 57-66, 1998. 

Other atmospheric factors such as gaseous impurities in the air (e.g. sulfur dioxide, ammonia, carbon monoxide, ozone, carbon dioxide, halogen compounds, or formaldehyde) and solid impurities in the atmosphere (airborne dust, sand, and soot) result in an acceleration of aging processes in polymers. Whereas the effects of the gaseous impurities on polymers are mainly chemical in nature, the solid particles mostly cause abrasive damage to the plastic surface. 

Acid rain A solution of acidic compounds formed when sulfur and nitrogen oxides react with water droplets and airborne particles. 

Large amounts of smoke from oil slick burning can result in oil rain. The formation and possible sinking of extremely viscous and dense residues can damage the sea bed and its inhabitants. The viscous residue may also be transported to shorelines and beaches by ocean tides or currents. Airborne irritants and possibility of secondary fire are sources of concern when combustion has to be carried out close to residential areas. Carbon monoxide, sulfur dioxide, and polycyclic aromatic hydrocarbons (PAH) are common toxic compounds emitted while burning oil on water. 

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