Atrazine biodegradation modulated by clays and clay/humic acid complexes.
The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment.
Laboratoire de Synthèse et Etude de Systèmes à Intérêt Biologique, UMR-CNRS 6504, Université Blaise Pascal, 63177 Aubière Cedex, France. Pascale.Besse@univ-bpclermont.fr
Pascale
P
Besse-Hoggan
Tatiana
T
Alekseeva
Martine
M
Sancelme
Anne-Marie
AM
Delort
Claude
C
Forano
D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D001280:Atrazine / Q000737:chemistry / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D000077215:Clay; D006540:Herbicides / Q000737:chemistry / Q000378:metabolism*; D006812:Humic Substances / Q000032:analysis* / Q000382:microbiology; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism*
D000538:Aluminum Silicates; D006540:Herbicides; D006812:Humic Substances; D012989:Soil Pollutants; D001280:Atrazine; D000077215:Clay