ABSTRACT
This chapter reviews the formation of hydroxyl as relevant to agricultural field water and reaction pathways as they relate to the fate of pesticides and aromatic contaminants. It presents methods for measuring steady-state hydroxyl concentrations and describes the use of one of these to determine the relative reaction rates of hydroxyl with common pesticides. To assess the relationship between persistence and reactivity, carbaryl, carbofuran, and hexazinone were irradiated in field water under various conditions. The importance of hydroxyl in the degradation of pollutants in the aquatic environment has received increased attention as the sources, and concentrations in natural waters became better known. Selection of an appropriate probe requires that the degradation mechanism be specific for hydroxyl or that the products not be appreciably degraded during the course of the measurement. The extreme reactivity of hydroxyl makes it difficult to monitor directly, requiring the use of surrogate reactions for elucidating reaction pathways and quantifying the concentrations present under various environmental conditions.
