Rhizosphere pH gradient controls copper availability in a strongly acidic soil

Bravin Matthieu, Tentscher P., Rose Jérôme, Hinsinger Philippe. 2009. Rhizosphere pH gradient controls copper availability in a strongly acidic soil. Environmental Science and Technology, 43 (15) : pp. 5686-5691.

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Liste HCERES des revues (en SHS) : oui

Thème(s) HCERES des revues (en SHS) : Psychologie-éthologie-ergonomie

Abstract : Using a root mat approach, we quantified how root-induced alkalization controlled the establishment of copper (Cu) gradients in the rhizosphere of durum wheat (Triticum turgidum durum L.) cropped in a strongly acidic, Cu-contaminated soil. Rhizosphere pH increased over 6 mm in soil, reaching up to+2.8 units close to root mat surface. Conversely, free Cu2+ activity decreased by 3 orders of magnitude and total Cu concentration by 3-fold in the rhizosphere solution, while labile Cu assessed by DGT (diffusive gradients in thin films) was halved. The DIFS (DGT-induced flux in soils and sediments) model failed to adequately simulate Cu depletion in the rhizosphere solution, showing that root-induced alkalization almost entirely explained Cu depletion while plant uptake had little impact. We modeled the observed pH gradient to recalculate its radial extension around a single root. The gradient of free Cu2+ activity in solution, deduced from pH modeling, extended over 1-4 mm in the rhizosphere depending on root radius and OH- efflux from root. Rhizosphere alkalization dramatically decreased root exposure to Cu, substantiating that root-induced chemical changes in the rhizosphere should be better accounted for to assess metal bioavailability to plants. (Résumé d'auteur)

Mots-clés Agrovoc : Triticum turgidum, Cuivre, Rhizosphère, Disponibilité d'élément nutritif, pH du sol, Relation plante sol, Alcalinisation, Sol pollué, Sol acide

Mots-clés géographiques Agrovoc : France

Classification Agris : P33 - Soil chemistry and physics
F01 - Crops
P02 - Pollution

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

Auteurs et affiliations

  • Bravin Matthieu, CIRAD-PERSYST-UPR Recyclage et risque (FRA) ORCID: 0000-0002-1436-7837
  • Tentscher P., INRA (FRA)
  • Rose Jérôme, Université d'Aix-Marseille (FRA)
  • Hinsinger Philippe, INRA (FRA)

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