Emissions to the Atmosphere

Source or activity Carbon exposed (Tg C/year) Carbon released (Tg C/year) N/C ratio (% by weight) Nitrogen released (Tg N/year) 

Element or compound Emission ratio Emission from biomass burning Total emissions from all sources 

Emission ratios for C and S compounds are in moles relative to CO2 those for N compounds are expressed as the ratios of emission relative to the N content of the fuel the emissions of TPM, POC, EC, and K are in grams per kilogram of fuel C. The emission ratios have been derived from information in (26, 29-31, 36, and 46). In calculating the ranges of total emissions, we used only half the ranges of total C emissions (2500-3900 Tg of C per year) and the emission ratios (for instance, 7.5-12.5 % for CO). A similar procedure was followed for the N compounds 

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The selection of equipment for the treatment of solid particle emissions to the atmosphere depends on a number of factors ... 

There always is a relation between fuel composition and that of hydrocarbon emissions to the atmosphere, whether it concerns hydrocarbon emissions from evaporative losses from the fuel system, or from exhaust gases. This is the reason that environmental protection regulations include monitoring the composition of motor and heating fuels. We will describe here the regulations already in existence and the work currently underway in this area with its possible effects on refining. 

Although the first impulse for emission reduction is often to add a control device, this may not be the environmentally best or least cosdy approach. Process examination may reveal changes or alternatives that can eliminate or reduce pollutants, decrease the gas quantity to be treated, or render pollutants mote amenable to collection. Following are principles to consider for controlling pollutants without the addition of specific treatment devices, ie, the fundamental means of reducing or eliminating pollutant emissions to the atmosphere (30) ... 

Another factor is the potential economic benefit that may be realized due to possible future environmental regulations from utilizing both waste and virgin biomass as energy resources. Carbon taxes imposed on the use of fossil fuels in the United States to help reduce undesirable automobile and power plant emissions to the atmosphere would provide additional economic incentives to stimulate development of new biomass energy systems. Certain tax credits and subsidies are already available for commercial use of specific types of biomass energy systems (93). 

Forest systems also act as sources of CO2 when controlled or uncontrolled burning and decay of litter occur. In addition, release of ethylene occurs during the flowering of various species. One additional form of emission to the atmosphere is the release of pollen grains. Pollen is essential to the reproductive cycle of most forest systems but becomes a human health hazard for individuals susceptible to hay fever. The contribution of sulfur from forests in the form of dimethyl sulfide is considered to be about 10-25% of the total amount released by soils and vegetation (12). 

For many industrialized countries, efforts to improve the outdoor air quality have been under way for the majority of this century. In many locations around the world, significant improvements have taken place. Air quality in many major cities such as London, New York, and Chicago has improved from the conditions present in the first half of the twentieth century. Mechanisms and control programs are in place in the developed countries to continue the improvement of ambient air quality. Considerable effort and energy have been expended to characterize, evaluate, and control air pollution emissions to the atmosphere. 

Discuss the use of data telemetered to the office of the air pollution control agency from automatic instruments measuring ambient air quality and automatic instruments measuring pollutant emissions to the atmosphere as air pollution control regulatory means. 

Most petrochemical processes are essentially enclosed and normally vent only a small amount of fugitive emissions. However, the petrochemical processes that use air-oxidation-type reactions normally vent large, continuous amounts of gaseous emissions to the atmosphere (10). Six major petrochemical processes employ reactions using air oxidation. Table 30-5 lists the atmospheric emissions from these processes along with applicable control measures. 

Emissions to the atmosphere from ammonia plants include sulfur dioxide (SOj), nitrogen oxides (NOJ, carbon monoxide (CO), carbon dioxide (COj), hydrogen sulfide (HjS), volatile organic compounds (VOCs), particulate matter, methane, hydrogen cyanide, and ammonia. The two primary sources of pollutants, with typical reported values, in kilograms per ton (kg/t) for the important pollutants, are as follows ... 

VISCREEN is an initial screening model for visual impact caused by emissions to the atmosphere. Click the filename to download the file. 

Hydrometallurgy has frequently been praised for not having any highly adverse impact on the environment. The problems associated with sulfur dioxide emission to the atmosphere from the roasters and the smelters of sulfidic sources have created much interest in treating these resources by hydrometallurgical methods. Moreover, the extreme amount of effort that has gone into the development of hydro-based processes for the sulfidic sources... 

In a pneumatic conveying system, air or some other gas is used to transfer solids from one place to another. These systems are entirely enclosed, hence the product loss is small, contamination is minimized, and the problem of dust emission to the atmosphere is greatly reduced. There are many different systems only a few will be presented here. 

Before the syngas from WGS reactor is separated into its primary components, the sulphur compounds, mainly in COS and H2S form, are removed to avoid its emission to the atmosphere. Sulphur is then recovered in either as solid in a Claus plant or as sulphuric acid. 

The primary source of lead in the environment has historically been anthropogenic emissions to the atmosphere. In 1984, combustion of leaded gasoline was responsible for approximately 90% of all anthropogenic lead emissions. EPA phased out the use of lead alkyls in gasoline, however, and by 1990, auto emissions accounted for only 33% of the annual lead emissions (EPA 1996h). Use of lead additives in motor fuels was totally banned after December 31, 1995 (EPA 1996f). The ban went into effect on February 2, 1996. Atmospheric deposition is the largest source of lead found in soils. Lead is transferred... 

In 1982-1983, the baseline value for daily intake of lead by inhalation in a nonurban environment was estimated to be 0.5 pg/day for a 2-year-old child. The baseline value was based on an average atmospheric lead concentration of 0.1 pg/m3 and an indoor/outdoor lead concentration ratio of 0.5. In an urban environment, the indoor/outdoor ratio was assumed to be approximately 0.8 (EPA 1986a). Drastic reductions in the lead content of gasoline since 1986 have resulted in a 64% decrease in lead emissions to the atmosphere (see Section 5.4.1). 

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