Methyl parathion degradation and metabolism in soil: Influence of high soil-water contents

Mineralization of ¹⁴C]methyl parathion (MP) in Cecil sandy loam was considerably reduced when soil-water content was near saturation. Despite the fact that amounts of MP residue in soil held at 10?0 kPa after 35 days were about the same, larger amounts of metabolites were accumulated and higher amounts of non-extractable ¹⁴C-activity were formed in soil held at ? 2.5 kPa than held at ? 6 kPa. Three principal metabolites, p-nitrophenol (PNP), p-aminophenol (PAP) and a water-soluble polar product ($\text{R}{}_{\mathrm{?}}\text{= 0}$), were detected in soil held at ? 2.5 kPa but only PNP and PAP were detected in soil held at ? 6 kPa. The major metabolite PNP behaved like parent MP, in that it was rapidly mineralized in soil held at ? 6kPa. Much slower mineralization was observed in soil held at ? 2.5kPa.