CHLORAMBEN (AMIBEN) DEGRADATION JN SOIL

Summary. When columns of three soil types were perfused with a microbial medium containing 5·7 and 26·9 ppm ¹⁴COOH-labelled chloramben, there was a rapid decrease in the ¹⁴C activity remaining in solution, attributable to soil adsorption. Soil pH and organic matter content were the primary factors controlling chloramben adsorption. Soil pH may enhance adsorption through its effect on the number of soil anion exchange sites, and sites for polyvalent cation bridging and H bonding. Following adsorption, liver decreases in solution ¹⁴C-chloramben activity were attributed to degradation; ¹⁴CO2 evolved during perfusion amounted to 25–30% of the total decrease in ¹⁴C-chloramben from solution. It was concluded that more than 90% of the ¹⁴C-activity remaining in solution could be attributed to intact chloramben. Thus, decarboxylation appeared to be the primary mechanism of chloramben degradation in soils. Lag phases observed during degradation and subsequent investigations with re-amended solutions implicated the soil microflora; even at chloramben concentrations of 26.9 ppm no toxic effect on the chloramben-degrading micro-organisms was apparent.
Dégradation du chlorambène amibène) dans le sol