High elevations

Since SO2 and NO2 are criteria pollutants, their emissions are regulated. In addition, for the purposes of abating acid deposition in the United States, the 1990 Clean Air Act Amendments require that nationwide SO2 and NO emissions be reduced by approximately 10 million and 2 million t/yr, respectively, by the year 2000. Reasons for these reductions are based on concerns which include acidification of lakes and streams, acidification of poorly buffered soils, and acid damage to materials. An additional major concern is that acid deposition is contributing to the die-back of forests at high elevations in the eastern United States and in Europe. 

The equilibrium vapor pressure above a confined liquid depends only on temperature. The fraction of the total pressure exerted by vapor pressure determines the composition of the vapor-air mixture. Thus when the total pressure is reduced, for example at high elevations or in vacuum tmcks, the vapor concentration in air increases. Since flash points are reported at a... 

In the eastern United States, high elevation red spruce and fir forests found in the Northeast have suffered significant injury and mortality. Significant... 

Schemenauer, R.S., Schuepp, P., Kermasha, S., and Cereceda, P. In NATO Advanced Research Workshop Acid Deposition Processes at high Elevation Sites, D. Reidel Publisher, 1988, pp. 359-374.

Given a sufficient period of time, in the absence of tectonic processes, continents would presumably be eroded flat to about sea level. It is not surprising, therefore, that most tectonically quiet areas on continents tend to have low elevations and are often flat, whereas tectonically active areas, mostly mountain belts, have high elevations and steep slopes (Figs 9-2 and 9-4). 

Fig. 16-4 pH sensitivity to SO4- and NH4. Model calculations of expected pH of cloud water or rainwater for cloud liquid water content of 0.5 g/m. 100 pptv SO2, 330 ppmv CO2, and NO3. The abscissa shows the assumed input of aerosol sulfate in fig/m and the ordinate shows the calculated equilibrium pH. Each line corresponds to the indicated amoimt of total NH3 + NH4 in imits of fig/m of cloudy air. Solid lines are at 278 K, dashed ones are at 298 K. The familiar shape of titration curves is evident, with a steep drop in pH as the anion concentration increases due to increased input of H2SO4. (From Charlson, R. J., C. H. Twohy and P. K. Quinn, Physical Influences of Altitude on the Chemical Properties of Clouds and of Water Deposited from the Atmosphere." NATO Advanced Research Workshop Acid Deposition Processes at High Elevation Sites, Sept. 1986. Edinburgh, Scotland.)... 

Niacin can be combined with a fibrate in patients with high elevations in serum triglycerides. The combination may increase the risk of myopathy compared to either agent alone. 

The most common way radon enters a building is when lower indoor air pressure draws air from the soil, bedrock, or drainage system into the house. If there is radon in the soil gas, it will also be drawn in. Just as gravity will make water flow from a high elevation to a lower elevation, pressure differences will make radon-laden air move from an area of higher pressure to an area of lower pressure. For a variety of reasons, most buildings tend to maintain an indoor air pressure lower than outdoor air pressure. If cracks and holes in the foundation are open to the soil, radon will be drawn indoors. Radon movement by pressure differences is called pressure-driven transport. 

Stabilizing agents are used to maintain drilling fluid rheological properties at highly elevated downhole temperatures. Chromium and chromium-free lignosulfonates, polyglycol ethers, sodium polystyrene sulfonate-co-maleic anhydride), and a melanin polymer have been used in this application. Additives such as sodium diethyldi-thiocarbamate have been used to stabilize aqueous polysaccharides such as xanthan gum (18). 

Melegos, D. N., et al. (1999). Highly elevated levels of prostaglandin D synthase in the serum of patients with renal failure. Urology 53, 32-7. 

Friedland, A.J. and A.H. Johnson. 1985. Lead distribution and fluxes in a high-elevation forest in northern Vermont. Jour. Environ. Qual. 14 332-336. 

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