Sulfur dioxide atmospheric concentrations

The atmospheric sulfur dioxide (SO2) concentration over a certain region is 0.12 ppm by volume. Calculate the pH of the rainwater due to this pollutant. Assume that the dissolution of SO2 does not affect its pressure. 

There are two accepted methods for determining the sulfur dioxide (SO2) concentration in the atmosphere of interest. Both employ the affinity of lead oxide for sulfur dioxide. The most common technique uses sulfation plates. This procedure is covered in dqtail in ASTM G 91, Test Method for Monitoring Atmo heric SO2 Using the Sulfation Plate Technique. These devices are no longer available for purchsise, but must be prepared in the laboratory. The second method is the peroxide candle, similar in its function to the chloride candle. The procedure suggests a 30-day exposure, followed by a standard sulfate analysis. This procedure is covered by ASTM D 2010, Test Methods for Evaluation of Total Sulfation Activity in the Atmosphere by the Lead Dioxide Technique. In both cases, the results are calculated as the capture rate of SO2 per unit area, normally per m. ... 

If sulfur dioxide vapor is released, the irritating effect of the vapor will force personnel to leave the area long before they have been exposed to dangerous concentrations. To facilitate their rapid evacuation, there should be sufficient well-marked and easily accessible exits. If, despite all precautions, a person should become trapped in a sulfur dioxide atmosphere, partial protection may be gained by holding a wet cloth over the nose and mouth. Since sulfur dioxide vapor is heavier than air, the upper floors of buildings will normally have lower concentrations, but personnel may get trapped if assistance is not quick. 

There are two widely used methods for determining the sulfur dioxide (SO ) concentration in the atmosphere of interest Both employ the affinity of lead oxide to react with gaseous SO to form lead sulfate. The most common method used in corrosion work is the sulfation. These devices can be either purchased or prepared in the laboratory. They consist of small disks of lead oxide that are exposed facing the ground under a small shelter to prevent the reactive paste from being removed by the elements [15]. 

An evaporator—crystallizer is used to reverse the sodium bisulfite formation reaction and release the sulfur dioxide as a vapor. The regenerated sodium sulfite, which crystallizes out of solution, is redissolved and returned to the absorber. The absorber overhead gas can be vented to the atmosphere. A concentrated sulfur dioxide stream is produced as a by-product of this process. 

Particulate emissions are controHed mainly through venting, baghouses and water scmbbers. Atmospheric zinc loss is estimated at 100 g/1 or zinc mines, mostly from handling dry ore and concentrate and wind erosion of tailing pHes. Sulfur dioxide emissions have been reduced by installing double absorption acid plants and improved containment of dilute gases. 

A variety of models have been developed to study acid deposition. Sulfuric acid is formed relatively slowly in the atmosphere, so its concentrations are beUeved to be more uniform than o2one, especially in and around cities. Also, the impacts are viewed as more regional in nature. This allows an even coarser hori2ontal resolution, on the order of 80 to 100 km, to be used in acid deposition models. Atmospheric models of acid deposition have been used to determine where reductions in sulfur dioxide emissions would be most effective. Many of the ecosystems that are most sensitive to damage from acid deposition are located in the northeastern United States and southeastern Canada. Early acid deposition models helped to estabUsh that sulfuric acid and its precursors are transported over long distances, eg, from the Ohio River Valley to New England (86—88). Models have also been used to show that sulfuric acid deposition is nearly linear in response to changing levels of emissions of sulfur dioxide (89). 

Sufficient evidence is available to indicate that atmospheric pollution in vaiying degrees does affect health adversely. [Amdur, Melvin, and Drinker, Effec t of Inhalation of Sulfur Dioxide by Man, Lancet, 2, 758 (1953) Barton, Corn, Gee, VassaUo, and Thomas, Response of Healthy Men to Inhaled Low Concentrations of Gas-Aerosol Mixtures, Arch. Lnviron. Health, 18, 681 (1969) Bates, Bell, Burnham, Hazucha, and Mantha, Problems in Studies of Human Exposure to Air Pollutants, Can. Med. A.s.soc. J., 103, 833 (1970) Ciocco and... 

Sulfur oxides (SO,) are compounds of sulfur and oxygen molecules. Sulfur dioxide (SO2) is the predominant form found in the lower atmosphere. It is a colorless gas that can be detected by taste and smell in the range of 1, (X)0 to 3,000 uglm. At concentrations of 10,000 uglm , it has a pungent, unpleasant odor. Sulfur dioxide dissolves readily in water present in the atmosphere to form sulfurous acid (H SOj). About 30% of the sulfur dioxide in the atmosphere is converted to sulfate aerosol (acid aerosol), which is removed through wet or dry deposition processes. Sulfur trioxide (SO3), another oxide of sulfur, is either emitted directly into the atmosphere or produced from sulfur dioxide and is readily converted to sulfuric acid (H2SO4). 

Health effects attributed to sulfur oxides are likely due to exposure to sulfur dioxide, sulfate aerosols, and sulfur dioxide adsorbed onto particulate matter. Alone, sulfur dioxide will dissolve in the watery fluids of the upper respiratory system and be absorbed into the bloodstream. Sulfur dioxide reacts with other substances in the atmosphere to form sulfate aerosols. Since most sulfate aerosols are part of PMj 5, they may have an important role in the health impacts associated with fine particulates. However, sulfate aerosols can be transported long distances through the atmosphere before deposition actually occurs. Average sulfate aerosol concentrations are about 40% of average fine particulate levels in regions where fuels with high sulfur content are commonly used. Sulfur dioxide adsorbed on particles can be carried deep into the pulmonary system. Therefore, reducing concentrations of particulate matter may also reduce the health impacts of sulfur dioxide. Acid aerosols affect respiratory and sensory functions. 

Preferably, the HjS flare system should consist of a segregated header and separate line routed up the side of a conventional elevated flare stack, sharing the same structure, pilots and igniters. However, the HjS header may be tied into the regular flare seal drum if there are special mechanical design problems associated with the separate stack e.g., in the case of a flare which is to be dismantled for overhaul. Flare elevation must be sufficient to meet atmospheric pollution and ground level concentration requirements for the sulfur dioxide produced. 

The environmental problem of sulfur dioxide emission, as has been pointed out, is very much associated with sulfidic sources of metals, among which a peer example is copper production. In this context, it would be beneficial to describe the past and present approaches to copper smelting. In the past, copper metallurgy was dominated by reverberatory furnaces for smelting sulfidic copper concentrate to matte, followed by the use of Pierce-Smith converters to convert the matte into blister copper. The sulfur dioxide stream from the reverberatory furnaces is continuous but not rich in sulfur dioxide (about 1%) because it contains carbon dioxide and water vapor (products of fuel combustion), nitrogen from the air (used in the combustion of that fuel), and excess air. The gas is quite dilute and unworthy of economical conversion of its sulfur content into sulfuric acid. In the past, the course chosen was to construct stacks to disperse the gas into the atmosphere in order to minimize its adverse effects on the immediate surroundings. However, this is not an en-... 

Oxidative microcoulometry has become a widely accepted technique for the determination of low concentrations of sulfur in petroleum and petroleum products (ASTM D3120). The method involves combustion of the sample in an oxygen-rich atmosphere followed by microcoulometric generation of a triiodide ion to consume the resulting sulfur dioxide. It is intended to distinguish the technique from reductive microcoulometry, which converts sulfur in the sample to hydrogen sulflde that is titrated with coulometrically generated silver ion. 

Many deleterious effects have been associated with photochemically polluted air ozone is deflnitely associated with respiratory problems, plant damage, and material damage PAN has deflnitely been associated with plant damage, and some other members of this class of chemical compounds have been associated with eye irritation the hydroxyl radical is considered to be an important factor in the conversion of gas-phase intermediates to end products, such as sulfur dioxide to particulate sulfate the particulate complex is responsible for haze formation and has also been associated with eye irritation and respiratory effects. The aldehydes have been associated with eye irritation. Ozone and PAN themselves do not cause eye irritation. For purposes of control, much more research is needed, in order to relate the laboratory data about the concentrations of these various materials that have significant effects to their formation in the atmosphere from emission and their atmospheric distribution. The lack of convenient measurement methods has hindered progress in gaining this understanding. 

Further studies are needed to give better dose-response information and to provide a frequency distribution of the population response to oxidants alone and in combination with other pollutants at various concentrations. Such studies should include the effects of mixed pollutants over ranges corresponding to the ambient atmosphere. With combinations of ozone and sulfur dioxide, the mixture should be carefully characterized to be sure of the effects of trace pollutants on sulfate aerosol formation. The design of such studies should consider the need to use the information for cost-benefit analysis and for extrapolation from animals to humans and from small groups of humans to populations. Recent research has indicated the possibility of human a ptation to chronic exposure to oxidants. Further study is desirable. 

Chemical/Physical. At room temperature, concentrated sulfuric acid will react with pyrene to form a mixture of disulfonic acids. In addition, an atmosphere containing 10% sulfur dioxide transformed pyrene into many sulfur compounds, including pyrene-1-sulfonic acid and pyrenedisulfonic acid (Nielsen et al., 1983). 

Steel objects, when exposed to humid atmospheres or when immersed in electrolytes, corrode at a rapid rate. For example, abrasively polished, cold-rolled steel panels will show signs of rust within 15 minutes when immersed in dilute chloride solutions with pH in the range of 7-10. One of the methods used to control this rapid corrosion is to coat the metal with a polymeric formulation such as a paint. The role of the paint is to serve primarily as a barrier to environmental constituents such as water, oxygen, sulfur dioxide, and ions and secondarily as a reservoir for corrosion inhibitors. Some formulations contain very high concentrations of metallic zinc or metallic aluminum such that the coating provides galvanic protection as well as barrier protection, but such formulations are not discussed in this paper. 

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