Biodegradation of atrazine in the presence of soil models

摘要

Atrazine, still a widely used herbicide for control of broad leaf weeds in major crops (com, sugarcane), is a relatively common contaminant of groundwater. Before entering this compartment, atrazine is first in contact with soil where degradation by microorganisms occurs. Within the framework of a CNRS programme, we investigated the sorption and biodegradation of atrazine by Pseudomonas sp. strain ADP in the presence of different soil models. Humic acids were chosen as a model of the organic part of soil, and anionic (Layered Double Hydroxide = LDH) and cationic (Bentonites) clays were chosen as models for the mineral part. No atrazine adsorption on LDH occured, but the presence of this matrix in the incubation medium increased dramatically the rate of its biodegradation. With Ca-bentonites, the effects observed are completely reversed: strong adsorption of atrazine and decrease of the rate of biodegradation. The use of humic acid-clay complexes lead to a strong increase in the sorption capacities of atrazine.