No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Ever since air pollution became a national concern in the 1950's, more and more emphasis has been placed on collection of representative air samples for many purposed, to include (1) evaluation of the degree to which national ambient air quality standards are being met and (2) to monitor maximum emission levels from point sources. Until recently efforts were directed toward qualitative methods of siting monitors for representative sampling. Since the dispersion of effluents is most complex, the quality of the data collected on the basis of judgment and, more or less, incremental siting about the source, has become suspect. Furthermore, with the increasing demands for monitoring due to international growth in network monitoring systems, amendments to the Clean Air Act and the legislation on the Prevention of Significant Deteoriation of Air Quality, it is not cost-effective to encircle point sources with large numbers of equally spaced monitors. This paper discussed the history of air pollution concerns that have resulted in the need for monitoring; the development of siting techniques through largely qualitative measures; and finally, summarizes three quantitative methodologies for monitoring point sources. Emphasis is placed on the methodology developed by Noll, et al., (1977), based on the author's belief that this methodology represents the state of the art.

No description available.

No description available.

Three studies were performed to investigate the impact of air pollution on high-elevation red spruce-Fraser fir forests in the Southern Appalachians. In the first study, red spruce (Picea rubens Sarg.) and Fraser fir (Abies fraseri (Pursh.) Poir.) seedlings were submitted to long-term (2.5 yrs), multiple growing cycle (4 and 5, respectively), intermittent ozone fumigations (0.025, 0.070, and 0.150 ppm). No effect of ozone exposure on growth and gas exchange of the seedlings was found. Net photosynthesis at saturating light intensity was reduced in both species and the light compensation point was shifted upwards in spruce when exposed to ozone. Fraser fir seedlings showed inconsistent responses of CO₂ curve parameters to ozone exposure. There were indications that ozone exposure modified cell wall modulus of elasticity in both species. In the second study, the impact of summer exposure to ambient pollutants on winter hardiness in red spruce seedlings was examined. The seedlings were subjected to the following summertime treatments while kept in exclusion chambers on the top of Whitetop Mountain (Virginia): ambient air and clouds, ambient air with clouds excluded, charcoal filtered air, and chamberless control treatment. During the following winter the seedlings were placed in Blacksburg (Virginia), in two locations: in the open and in a shadehouse. A number of conducted tests indicated that there were significant differences in winter damage between the chamber treatments and chamberless control, as well as between the winter exposure locations. Among the summer chamber exposure regimes, the treatment excluding clouds seemed to perform the best (although not all the evidence supports the latter statement). In the third study, the physiology of red spruce trees of various sizes (seedlings, saplings, and overstory trees), growing on two sites on the top of Whitetop Mtn., was compared and related to ambient ozone concentration. Some seedlings were treated with an antioxidant EDU, to help evaluate the impact of ozone on their physiology. The trees of various sizes showed clear differences in gas exchange, with overstory trees photosynthesizing at the lowest rates, and seedlings - at the highest. Overstory trees also showed more negative shoot water potential and higher night respiration than smaller tree sizes. No deleterious effects of ambient ozone on red spruce physiology were detected. / Ph. D.