Atmospheric Environment (1967)最新文献

Observations of lead $\text{206}\text{207}$ ratios and trace element concentrations in atmospheric aerosols at a rural location in Ontario, Canada confirm results of a previous study of urban aerosols that showed there are significant differences in the isotopic composition of lead from Canadian autos, Canadian smelters and eastern American sources. Lead measurements in fall 1984 and spring 1986 were apportioned to the respective sources as follows: for 1984 (55, 2, 43%) and for 1986 (69, 7, 24%). Lead isotopic and meteorological information point to In as the best elemental tracer of emissions from selected northern Canadian smelters.

The trend of annual average sulfate and nitrate ion concentrations in precipitation at 17 stations in eastern North America over 7 years 1979–1985 is estimated and compared with a modeled trend. The observed concentrations fluctuate from year-to-year about a mean value with a standard deviation of 12.7% on average. The average slope of a linear regression line at the 17 stations is −2.8% a⁻¹ for sulfate and −0.4% a⁻¹ for nitrate. The modeled trend at these stations, which assumes constant meteorology but a year-to-year varying emission inventory, is −2.4% a⁻¹ for sulfate and −0.9% a⁻¹ for nitrate.

An estimate is made of the emissions of the five main air pollutants resulting from combustion processes: sulphur oxides (SO_x), nitrogen oxides (NO_x), total suspended particles (TSP), CO and volatile organic compounds (VOC) which include gases. An initial estimate, intended to provide some indication of the emission time trend, covers the years 1976, 1980 and 1984. Here emissions are divided according to both large fuel-consuming sectors (industry, agriculture, thermal power plants, residential and commercial, transportation), and the type of fuel used (coal, lignite, natural gas, oil products).

A further estimate is made, with reference to 1980, in which identified emissions are related to individual Italian regions and to the large activity sectors. For the same year emissions are grouped with reference to the 150 km × 150 km EMEP grid.

The rotating shadowband photometer (RSP) is a simple, low-cost instrument that automatically measures the total, diffuse and direct solar illuminance. On clear days, the direct component yields a measure of the total column extinction. This extinction calculation compares favorably with an independent and more conventional determination of extinction. The column extinction measurements can be corrected for the effect of stratospheric aerosols, thereby yielding the lower atmosphere extinction coefficient. This extinction coefficient should be useful in assessing small changes in atmospheric visibility over the long term.

Dominant spatial and temporal theories of acid rain in the U.S. are identified, followed by brief comments on how historical data have generally been used in modern acid rain research. A frequently-cited 1982 article by E.B. Cowling is examined, one that has influenced much thinking on the history of acid rain. The article overlooks early American smelters, however, and the role they played in the true history and geography of acid rain in the United States. Continuing with this theme, a connection is established between acid rain and turn-of-the-century smelter smoke problems. Literature on the latter subject is discussed, and American and German examples are given. A beginning is then made on writing acid rain's neglected chapter, focusing on Tennessee's Copper Basin (Ducktown District) where copper smelting dates back to the 1850s. A short historical overview of this area's smelting operations is given, with particular attention to the air pollution and other environmental problems resulting from large emissions of sulfur dioxide. Five additional early smelter sites for potential study are mentioned as well. The paper concludes with some observations regarding the way in which expanded research of early smelter sites could affect the general perception of acid rain in the U.S. It is also suggested that such research might contribute to a better atmosphere for making decisions and policies pertaining to the phenomenon as it exists today.

Taking into account the wind speed perturbations from the deterministic equation of conservation of the molecular species of the pollutant we obtained the corresponding stochastic differential equation. Because there is no mathematical reason to discriminate between its Ito and Stratonovich interpretations, we retained, on physical grounds, the Stratonovich interpretation and we derived the equation of the expected value of the pollutant concentration.

Ozone plays an important role in the physicochemical interactions between plumes and background air. During two field programs conducted at Cordemais in fall 1984 and at Le Havre in fall 1985, concentration measurements were performed in background air and in the plumes of fossil-fuel fired power plants. In background air, the daily average ozone concentration varied between 15 and 60 ppb depending on solar irradiation, pollution level and atmospheric stability. Maximum values of 100 ppb were observed in industrial area plumes. In the power plant plume, consumption of atmospheric ozone by emitted NO is important during the first 5 km downwind of the power plant but does not totally explain some important formation of NO₂ identified at short distances downwind of the power plant.

Halogenated methanes, ethanes and ethenes have been determined quantitatively in the soil-air and in the atmosphere in forests of southern F.R.G.; the levels in both compartments are similar for most halocarbons, except for trichloromethane. The concentrations of the latter in soil-air are consistently higher than in the air above the ground, which is most pronounced on a mountain crest with severe tree damage.