Sulfur dioxide phytotoxic pollutant

Oxidant air pollutants exist as parts of a complex mixture of gases, many of which may be phytotoxic. However, expect for ambient-air studies and simulated photochemical-oxidant studies, little research was done with pollutant combinations until the classic work of Menser and Heggestad in 1966. It is of interest that Thomas et suggested that sulfur dioxide might lessen the effect of oxidants in causing foliar injury to pinto bean. Middleton et working with ratios of sulfur... 

Sulfur dioxide (SO2) is regarded as the most important phytotoxic air pollutant emitted from industrial (point) sources. 

Air pollutants can affect plants both directly and indirectly. The principal phytotoxic air pollutants are ozone, nitric oxide, nitrogen dioxide, sulfur dioxide, fluorides, and peroxyacyl nitrate (PAN). Their toxic effects have been demonstrated convincingly through field measure-... 

FIGU RE 1.1 Illustration of the definition of environmental chemistry exemplified by the life cycle of a typical pollutant, sulfur dioxide. Sulfur present in fuel, almost always coal, is oxidized to gaseous sulfur dioxide, which is emitted to the atmosphere with stack gas. Sulfur dioxide is an air pollutant that may affect human respiration and may be phytotoxic (toxic to plants). Of greater importance is the oxidation of sulfur dioxide in the atmosphere to sulfuric acid, the main ingredient of acid rain. Acidic precipitation may adversely affect plants, materials, and water, where excessive acidity may kill fish. Eventually, the sulfuric acid or sulfate salts end up in water or in soil. 

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