Direct Effects of Atmospheric Sulfate Deposition on Vegetation

Acid sulfate aerosol (500 μg/m3) had no effect on soybean or pinto bean after a single 4-h exposure. However, visible Injury and chlorophyll loss occurred when plants were sequentially exposed to acid aerosol and ozone (380 μg/m3) for 4 h. In yellow poplar seedlings exposed to ozone (200 μg/m3), sulfur dioxide (210 μg/m3) and simulated rain solutions (pH 5.6, 4.3 and 3.0) for 6 weeks, root dry weight, leaf area increase, mean relative growth rate and unit leaf rate decreased linearly with pH in ozone-treated plants. However, unit leaf rate and mean relative growth rate increased linearly in response to sulfur dioxide as solution acidity increased. Ambient wet and dry sulfate concentrations appear insufficient to directly impact vegetation.