Emissions of gaseous air pollutants have increased in the last years in spite of increased controls and concern for air quality. Predictions of future development also indicate that a further increase in emissions must be expected. From an extensive analysis of fuel use in conventional power plants in industry and for domestic heating, Brocke and Schade (1971) and Schade (1975) predict that sulfur dioxide (S02) emissions in the Federal Republic of Germany will increase from '3. 5 million t in 1969, over 4. 2 million t in 1973, to 4. 6 million t in 1980. Rasch (1971) predicts that emission of hydrogen chloride (HCI) from burning of wastes will increase from a present 8000 t/year to about 100000 t in 1980. Emission of gaseous fluoride compounds, in North Rhine Westphalia alone, are expected to increase from 7500 t in 1969 to 8800 t in 1985 (MAGS, 1972). Similar predic­ tions have also been made in the USA (Heggestadt and Heck, 1971). A doubling of S02 emissions from oil and particularly coal-fired power plants is expected between 1960 and 1980 (Wood, 1968; Lewis et aI. , 1974). When it is considered that total control of air pollutants is technically and especially economically impossible, it is important that, in the future, emissions are controlled within a technical and economic framework to such an extent that ambient pollutant concentrations near the ground present no hazard to man or his environment (BImSchG, 1974).

Inhalt

1. Materials and Methods.- 1.1 Apparatus for the Experimental Determination of Air Pollution Effects.- 1.1.1 Field Study Near a Sulfur Dioxide Source.- 1.1.2 Fumigation Experiments in the Field.- 1.1.3 Fumigation Experiments in Controlled-environment Chambers.- 1.1.4 Comparison of Experimental Methods.- 1.2 Air Analyses.- 1.3 Test Plants and Soils.- 1.4 Determination of Plant Responses.- 1.4.1 Growth, Yield, and Quality.- 1.4.2 Gas-exchange Measurements.- 1.4.3 Chemical Analysis of Plant Material.- 1.4.4 Electron-microscopic Analysis of Ultrastructure.- 2. Experimental Analysis of the Effects of Gaseous Air Pollutants.- 2.1 Criteria for the Evaluation of Air Pollution Effects.- 2.2 Influence of Concentration and Exposure Time.- 2.3 Significance of Continuous and Intermittent Pollutant Action.- 2.4 Effects of Gaseous Air Pollutants in Combination.- 2.5 Significance of External and Internal Growth Factors.- 2.5.1 Influence of Climatic Factors.- 2.5.1.1 Radiation.- 2.5.1.2 Temperature.- 2.5.1.3 Humidity.- 2.5.2 Edaphic Factors.- 2.5.2.1 Soil Moisture.- 2.5.2.2 Nutrition.- 2.5.3 Influence of Stage of Development and Leaf Age.- 2.5.3.1 Stage of Development.- 2.5.3.2 Leaf Age.- 2.5.4 . Specific, Varietal, and Individual Resistance.- 3. Comparisons of the Phytotoxic Characteristics of Sulfur Dioxide, Hydrogen Fluoride, and Hydrogen Chloride.- 3.1 Functions in Plant Metabolism.- 3.1.1 Sulfur.- 3.1.2 Fluorine.- 3.1.3 Chlorine.- 3.2 Accumulation of Pollutants in Plant Organs.- 3.2.1 Accumulation of S, F, and CI in Connection with Pollutant Dosage.- 3.2.2 Relationship Between Accumulation of Pollutants and Plant Injury.- 3.2.3 Pollutant Content in Plant Organs as an Indicator for Pollutant Activity.- 3.3 Hidden Injury.- 4. Discussion of the Suitability of Plant Responses as a Basis for Air Pollution Control Measures.- 4.1 Air Quality Criteria and Their Use in Setting Air Quality Standards.- 4.1.1 Air Quality Criteria.- 4.1.1.1 Sulfur Dioxide.- 4.1.1.2 Hydrogen Fluoride.- 4.1.1.3 Hydrogen Chloride.- 4.1.2 Air Pollution Standards.- 4.2 Plants as Indicators for Pollutants Containing Sulfur, Fluoride, and Chloride.- 4.3 Measures for the Reduction of Pollutant Action in Plant Stands.- 4.3.1 Cultivation of Resistant Species and Varieties.- 4.3.2 Fertilizing and Cultivation.- References.- Color Plates.