4501 Circle 75 Parkway Suite f-6320 Atlanta, ga 30339 (770) 953-4143 Table of Contents
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Air QualityAs in most expanding metropolitan areas, air pollution is an unwelcome and unhealthy byproduct of urban growth and development. In addition to reducing air pollution through energy conservation, trees also help to remove and store several major air pollutants. The CITYgreen air pollutant and carbon sequestration models estimated the amount of several major air pollutants that trees remove. Table 5 indicates the pollution removal benefits from each of the study sites. State Public Service Commissions (PSCs), the appointed bodies that regulate utilities, estimate the costs of externalities, or social costs, associated with energy production. An example of these costs is the health costs associated with treating the disease that pollutants would cause. The dollar value savings shown represent the savings of these externality costs derived from the trees’ storage of pollutants. The Old Neighborhood study site provided the greatest amount of savings, about $455 per year, due to its high canopy cover. With a smaller canopy cover, the Young Neighborhood site produced approximately $83 per year in air pollution removal benefits.
In addition to the air pollutant benefit analysis, CITYgreen estimates the amount of carbon that is sequestered and stored in trees. Carbon accounts for about half of the dry weight of most trees. Trees help to control the amount of carbon in two important ways – storage and sequestration. Carbon storage is the amount of carbon currently stored in a tree’s biomass while carbon sequestration is the rate at which trees absorb carbon (American Forests 1996). The CITYgreen carbon models estimate that the existing trees in all study sites store over 235 tons of carbon each year, an average of about 39 tons per site. The varying storage levels correspond to the different amounts of tree biomass at each site. A tree’s biomass can roughly be measured by analyzing the number of trees, the size of the trees, and the canopy percentage for each study site (American Forests 1996). For the rate of carbon sequestration, the CITYgreen software calculated an annual rate of carbon absorption of 0.67 tons for all study sites, an average of 0.11 tons per study site. The differing levels of sequestration also correspond to the wide range of vegetation biomass found at each site.
Annual carbon sequestration values can be calculated by multiplying the costs of pollution control by annual sequestration rates (McPherson et al. 1994). Using this method, the annual value of carbon sequestration ranges from almost $37 for the Downtown sample site to a high of about $250 for the Young Neighborhood site. The average value of carbon sequestered for all study sites is approximately $103 per year. As these estimates are based on the cost of controlling emissions, it is likely that they overestimate the value of reducing the pollution. These estimates do not take into consideration the adverse effects that pollution causes on human health, structures, and visibility before the pollutants are removed by trees (McPherson et al. 1994). Stormwater ManagementReducing volume and velocity of stormwater runoff is a significant part of stormwater management. CITYgreen stormwater analysis provided important insight into how trees can help to control stormwater runoff volume and velocity (peak flow rate). According to the analysis of the Macon-Bibb County study sites, existing trees reduce the volume of stormwater runoff by an average of 23 percent when compared to areas with no tree cover. The estimated volume of stormwater runoff ranges from 0.35 to a high of 3.25 inches per square inch. Not surprisingly, study sites having very little vegetation and large amounts of impervious surfaces (Office Building and Downtown commercial study sites) had the highest runoff volumes and peak flow rates. By contrast, study sites with high vegetation cover and low to medium impervious cover (Apartment Complex and Old Neighborhood sites) had the lowest runoff volumes and peak flow rates.
Directory: 2000 2000 -> Radioactivities n ewsletter of the a rgonne a mateur r adio c lub 2000 -> The neotectonic setting of Puerto Rico 2000 -> - 2000 -> Annex 1 to the Interim Report 2000 -> 1996 atlanta olympic games sailing competition 470 women 2000 -> 2000 End of Season Standings 2000 -> Stardust August, 2000 Star Class Newsletter for the 1 2000 -> 2000 Black College Football Classic Schedule date home visitor 2000 -> 2000 Black College Composite Football Schedule Saturday, August 26, 2000 2000 -> Administrative panel decision Download 0.68 Mb. Share with your friends:
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