Asteraceae degrade atrazine in the presence of iron under circumneutral conditions via a rhizosphere Fenton reaction

The objective of the present study was to degrade the herbicide atrazine in iron-containing media using several selected plant species under circumneutral conditions. The concentration of the root apoplastic H2O2 (CRAH) for 59 plant species was mainly measured using the potassium iodide-starch qualitative staining technique. Plant species with a range of CRAH values were used for the atrazine degradation. At pH 6.5, atrazine was immediately removed and most significantly by Asteraceae plants having high CRAH (≥ 1.5 mM) in the presence of Fe3+-nitrilotriacetate. Less biologically harmful degradation products (deethylatrazine and deisopropylatrazine) of the Fenton reaction were identified in the treated medium. Asteraceae plants were estimated to remove atrazine via a rhizosphere Fenton reaction which was more than twice that via plant uptake. This is the first report demonstrating direct and immediate degradation of atrazine in the medium by plant roots. The high CRAH of Asteraceae plants was connected with salinity/drought tolerance mechanisms and phylogenetic evolution. Roots of Asteraceae plants with high apoplastic H2O2 significantly degraded atrazine by transforming to less biologically harmful degradation products in the presence of iron under circumneutral conditions via the rhizosphere Fenton reaction.