Monitoring Gas Concentrations in Pollutant Exposure Systems: Defining Exposure Concentrations

Abstract

Several reasons have been offered in the recent literature to explain the disagreement in experimental results on the effects of SO² on plants. The tacit assumption that each research group is monitoring exposure concentration in a comparable manner is challenged. For example, in well-stirred chambers exposure concentrations are identical with outlet concentrations, yet several studies have interpreted plant response in terms of supply (i.e. inlet) concentrations. Experiments are presented that illustrate the extent to which supply concentrations can be depleted within chambers, and the magnitude of error in assuming supply to represent exposure concentrations. Definitions for exposure concentration in chamber, wind tunnel, and glasshouse systems are suggested.