HYDROXYL RADICAL-MEDIATED DEGRADATION OF PHENYLARSONIC ACID

摘要

Arsenic is present in natural waters in both inorganic and organic forms. Although the inorganic species are predominant, the presence of organoarsenic compounds, such as methylated and phenylated arsenic compounds, have been reported. Organoarsenic compounds, especially phenylated arsenic compounds, are used in agriculture to control cecal coccidiosis in poultry and promote growth, providing improved feed conversion, better feathering and increased egg production and pigmentation. 4-Hydroxy-3-nitrophenylarsonic acid (roxarsone), p-arsanilic acid, 4-nitrophenylarsonic acid, p-ureidophenylarsonic acid and phenylarsonic acid are all utilized in the broiler poultry industry as feed additives. Approximately 70% of broiler chickens produced in the U.S. are fed with roxarsone. Large quantities of arsenic are introduced into the environment through land application of poultry litter containing the phenylated arsenic feed additives, especially roxarsone. It is estimated that approximately 10~6 kilograms (Kg) per year of roxarsone and its degradation products are introduced into the environment from the disposal of poultry litter spread onto agricultural fields near the chicken houses (Cortinas et al., 2006). The knowledge and concern about the environmental impact and the ultimate fate of organoarsenicals applied to soils and other ecosystems is steadily growing.