Treesearch

Using simple analytical techniques, the amounts of air pollutants accumulated in winter snow were determined and the results correlated with lichen survival on trees. Pollutants measured were particulate matter, sulfate, and chloride. An inverse relationship was found between amounts of each of these pollutants and the abundance of various lichens.

A preliminary study has been made around a sulfite plant in the north of Sweden. The emission of sulfur dioxide increased considerably in 1950 as a consequence of the introduction of lye-burning. Using the pH in pine bark and two common lichen epiphytes as indicators, the resistant Parmelia physodes and the very sensitive Alectoria implexa, the area studied was divided into regions with different degrees of air pollution, mainly sulfur dioxide.

Quantitative data were obtained for arboreal species within 50 lowland forests in southeastern Ohio. Thirty-seven communities were dominated by Betula nigra L. and 13 were dominated by Acer saccharinum L. The acidic soils collected from B. nigra communities contained toxic concentrations of exchangeable aluminum and low concentrations of calcium and magnesium. Tree species diversity (Shannon-Weaver index) and species equitability were inversely related to high concentrations of exchangeable aluminum and hydrogen and directly related to high concentrations of exchangeable calcium and...

The short needle disease of pines consists of dwarfing, crooking, twisting, and excessive elongation of random needles, failure of buds to develop, reduced lateral branch development and the premature casting of needles. The disease was initially associated with a power plant source of air pollution in the eastern United States during 1969; at that time the cause of the disease was unknown.

Acidified precipitation may affect the productivity of forests by altering the availability of plant nutrients of by affecting the ability of trees to absorb and assimilate those nutrients. In this study, the short-term effects of simulated acid rain (pH range 5.6 - 2.3) upon the growth and nutrient relations of Eastern White Pine seedlings (Pinus strobus, L.) grown in a sandy loam soil were examined. Soil chemistry, soil leachate chemistry, seedling tissue chemistry, and seedling productivity were monitored. In spite of increased leaching of cations from the soil, resulting in near...

Most plants can take up nutrients from the atmosphere as well as from the soil solution. This capacity is especially important in natural ecosystems such as forests and bogs where nutrients from other sources are scarce and where fertilization is not a normal management procedure. Trees develop very large canopies of leaves and branches that extend high into the air. Thus, trees offer a very large surface for deposition and potential assimilation of substances dispersed in the atmosphere.

The effect of acidic precipitation on cation leaching in a second-growth Douglas-fir ecosystem at the Thompson Research Center is reviewed. Sulfate mobility and soil pH buffering power were tested by applications of heavy doses of sulfuric acid to the study plot. Sulfate at high concentrations proved to be immobilized, presumably by adsorption to soil sesquioxide surfaces. Soil sulfate adsorption was determined at varying sulfate concentrations, and two mechanisms of adsorption are implied by the shapes of the adsorption isotherms.

In recent years concern has been expressed about the danger of harmful pollution deposits which affect areas at great distances from the emission sources. The investigation was so designed that a possible reaction in growth resulting from a supposed acidification could be observed as far as possible. A poorer growth development was observed in regions, which are suspected of being more susceptible to acidification than those regions which are presumed to be less susceptible in this respect. We have found no good reason for attributing the reduction in growth to any cause other than...

An aerosol generator and wind tunnel system designed for use in aerosol deposition is described. Gross deposition on rough pubescent leaves was nearly 7 times greater than on smooth, waxy leaves. Results suggest that aerosol deposition, on a per unit area basis, for single horizontal streamlining leaves is similar to that for arrays of leaves under similar flow conditions. Wind reentrainment of PbCl2 particles was negligible while 2.54 cm of simulated rainfall was sufficient to remove 85 percent of recently applied aerosol.

Semi-empirical formulae are presented which can be used to estimate precipitation scavenging and dry deposition of particles and gases. The precipitation scavenging formulae are appropriate both for in- and below-cloud scavenging and comparisons with data indicate the importance of accounting for aerosol particle growth by water vapor condensation and attachment of the pollutant to plume or cloud particles. It is suggested that both wet and dry removal of gases is usually dictated by other than atmospheric processes. Dry deposition of particles to a canopy is shown to depend on canopy...