Grand Canyon

The United States Clean Air Act of 1977 set as a national goal the prevention of any future degradation and the reduction of any existing impairment of visibility in mandatory class I federal areas caused by anthropogenic air pollution. The Clean Air Act Amendments of 1990 reinforce the support of these goals. (See Chapter 22 foj a discussion of federal classes of areas.) These areas include most of the major national parks, such as the Grand Canyon, Yosemite, and Zion Park. This portion of the Clean Air Act ad-... 

Pltme Two-plane air oollision over Grand Canyon, Arizona June 30, 1956 128 Controlled airspaoe exptmded use of infrared as a warning indioalor... 

Grand Canyon University College of Nursing Phoenix, Arizona Adjunct Faculty... 

The pressure p of the air above any point on the Earth s surface relates ultimately to the amount of air above it. If we are standing high up, for example on the top of a tall mountain, there is less air between us and space for gravity to act upon. Conversely, if we stand at the bottom of the Grand Canyon (one of the lowest places on Earth) then more air separates us from space, causing the air pressure p to be much greater. 

M., "Aerosol Chemical Species Contribution to Visibility Reduction in the Southwestern United States " Proceedings of the Grand Canyon Conference on Plumes and Visibility, November 10-14, 1980. 

Tanner, R. L., and D. E. Schorran, Measurements of Gaseous Peroxides near the Grand Canyon—Implication for Summertime Visibility Impairment from Aqueous-Phase Secondary Sulfate Formation, Atmos. Environ., 29, 1113-1122 (1995). 

Application of a combination of all of these approaches can be particularly powerful when the requisite input data are available. For example, Malm and Gebhart (1997) used a combination of these source apportionment techniques to show that in the Grand Canyon area, about 50% of the sulfur in particles was associated with sources that also emitted Se and hence was attributed to coal-fired power plants in the region. A strong association with bromine was also found, suggesting that wood smoke was also a significant source of sulfur in this region. 

FIGURE 9.52 Mass concentrations of acidic and neutral elutable organics in fine particles ( 2.1 (im) at Hopi Point (Grand Canyon region), at San Nicholas Island in the Pacific Ocean upwind of Los Angeles, in West Los Angeles, and downwind at Rubidoux. The bare represent all of the organics that elute between the n-alkanes C and C , where n is shown under each bar. Note the different scales for concentrations (adapted from Mazurek et al., 1997). 

More recently, the uptake of water by tropospheric particles in relatively remote locations near the Grand Canyon and in a polluted urban area near Los Angeles was studied by Saxena et al. (1995) using a TDMA similar to the studies of McMurry and co-workers. Figure 9.58 shows the measured total water content of these particles in Claremont, California, east of Los Angeles, as a function of the water calculated to be associated with inorganics. As already discussed, a vari-... 

FIGURE 9.59 Measured and calculated water content of particles near the Grand Canyon in 1992 at an RH of 80-85% (adapted from Saxena et al., 1995). 

Malm, W. C., J. V. Molenar, R. A. Eldred, and J. F. Sisler, "Examining the Relationship among Atmospheric Aerosols and Light Scattering and Extinction in the Grand Canyon Area, J. Geo-phys. Res., 101, 19251-19265 (1996). 

Mazurek, M., K. A. Hallock, M. Leach, M. C. Masonjones, H. D. Masonjones, L. G. Salmon, and G. R. Cass, Visibility-Reducing Organic Aerosols in the Vicinity of Grand Canyon National Park ... 

Zhang, X. Q., P. H. McMurry, S. V. Hering, and G. S. Casuccio, Mixing Characteristics and Water Content of Submicron Aerosols Measured in Los Angeles and at the Grand Canyon, Atmos. Environ., 27A, 1593-1607 (1993). 

Layers of rock exposed in the Grand Canyon by the erosive action of the Colorado River provide a window on a billion years Of Earth s history. /From J. Grotzinger. T. H. Jordan, F Press, and R. Siever, Understanding Earth. 5th ed. (New York ... 

A fourth example of data showing the particle distribution was a study that used the DRUM sampler at Grand Canyon National Park in 1984 (22). Recording the size distribution of sulfur was necessary in helping to understand the effects of sulfur on visibility degradation because there were two size modes one near 0.3 xm and one around 0.1 xm. These modes were not present simultaneously but appeared somewhat anticorrelated (see August 14 in Figure 7). 

Figure 7. Sulfur size distributions at Grand Canyon National Parky August 1984, The finest aerosols are at the top (stage 8, around 0.1 xm), and the coarsest (8.5 to about 15 xm) are at the bottom. Most sulfur mass occurs between 0.34 and 0.56 xm (stage 6). The periods of August 14 are used for Table 111. (Reproduced with permission from reference 15. Copyright 1988.)...

Table III. Concentrations of Selected Elements at Grand Canyon National Park for an 8-h Period on August 16, 1984...

Oordasco, F,.M., C. Zenz, and S.T.. Demeler Environmental Respiratory Diseases, John Wiley Sons. Tnc, New York, NY, 1997 Crawford, M. Scientists Battle Over Grand Canyon Pollution. Science, 911 (February 23, 1990). 

Ashbaugh LL, Malm WC, Zadeh WZ (1985) A residence time probability analysis of sulfur concentrations at grand canyon national park. Atmos Environ 19 1263-1270... 

Hawkins DP, Bowring SA (1999) U-Pb monzaite, xenotime and titanite geochronological constraints on the prograde to post-peak metamorphic thermal history of Paleoproterozoic migmatites from the Grand Canyon, Arizona. Contrib Mineral Petrol 134 150-169... 

Atmospheric Effects. The presence of fine particles (0.1-1.0 mm in diameter) or N02 in the atmosphere can result in atmospheric haze or reduced visibility due to light scattering by the particles. The major effect of atmospheric haze has been degradation in visual air quality and is of particular concern in areas of scenic beauty, including most of the major national parks such as Great Smoky Mountain, Grand Canyon, Yosemite, and Zion Parks. 

With the efforts of conservation-minded citizens like President Theodore Roosevelt and Gifford Pinchot, America s first native-born professional forester, the United States Government soon became involved in preserving land and forming national parks. In fact, Roosevelt was so impressed with Muir and the need to protect our environment that he created five national parks overall. He added 140 million A (57 million ha) to the national forest system and set aside 18 areas of historic or natural interest (Bade, 1924). Yellowstone became the first national park in 1872, and with Muir s help was followed by the establishment of the Yosemite, Grand Canyon, Sequoia, and Mount Rainier national parks. In 1892, Muir established an organization that is now called the Sierra Club. 

---