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Plants increase arsenic in solution but decrease the non-specifically bound fraction in the rhizosphere of an alkaline, naturally rich soil

Obeidy C., Bravin M., Bouchardon J.L., Conord C., Moutte J., Guy B., Faure O.. 2016. Ecotoxicology and Environmental Safety, 126 : p. 23-29.

We aimed at determining the major physical-chemical processes that drive arsenic (As) dynamic in the rhizosphere of four species (Holcus lanatus, Dittrichia viscosa, Lotus corniculatus, Plantago lanceolata) tested for phytostabilization. Experiments were performed with an alkaline soil naturally rich in As. Composition of the soil solution of planted and unplanted pots was monitored every 15 days for 90 days, with a focus on the evolution of As concentrations in solution and in the non-specifically bound (i.e. easily exchangeable) fraction. The four species similarly increased As concentration in solution, but decreased As concentration in the non-specifically bound fraction. The major part (60%) of As desorbed from the non-specifically bound fraction in planted pots was likely redistributed on the less available fractions of As on the solid phase. A second part (35%) of desorbed As was taken up by plants. The minor part (5%) of desorbed As supplied As increase in solution. To conclude, plants induced a substantial redistribution of As on the less available fractions in the rhizosphere, as expected in phytostabilization strategies. Plants however concomitantly increased As concentration in the rhizosphere solution which may contribute to As transfer through plant uptake and leaching. (Résumé d'auteur)

Mots-clés : enracinement; alcalinité; plantago lanceolata; lotus corniculatus; holcus lanatus; lessivage du sol; transport des substances nutritives; arsenic; propriété physicochimique du sol; rhizosphère; france; dittrichia viscosa

Thématique : Chimie et physique du sol; Fertilité du sol; Physiologie et biochimie végétales

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