title: Localized metal solubilization in the rhizosphere of Salix smithiana upon sulfur application.
abstract: A metal-accumulating willow was grown under greenhouse conditions on a Zn/Cd-polluted soil to investigate the effects of sulfur (S(0)) application on metal solubility and plant uptake. Soil porewater samples were analyzed 8 times during 61 days of growth, while DGT-measured metal flux and O2 were chemically mapped at selected times. Sulfur oxidation resulted in soil acidification and related mobilization of Mn, Zn, and Cd, more pronounced in the rooted compared to bulk soil. Chemical imaging revealed increased DGT-measured Zn and Cd flux at the root-soil interface. Our findings indicated sustained microbial S(0) oxidation and associated metal mobilization close to root surfaces. The localized depletion of O2 along single roots upon S(0) addition indicated the contribution of reductive Mn (oxy)hydoxide dissolution with Mn eventually becoming a terminal electron acceptor after depletion of O2 and NO3(-). The S(0) treatments increased the foliar metal concentrations (mg kg(-1) dwt) up to 10-fold for Mn, (5810 ± 593), 3.3-fold for Zn (3850 ± 87.0), and 1.7-fold for Cd (36.9 ± 3.35), but had no significant influence on biomass production. Lower metal solubilization in the bulk soils should translate into reduced leaching, offering opportunities for using S(0) as environmentally favorable amendment for phytoextraction of metal-polluted soils.
authors.affiliation: Rhizosphere and Biogeochemistry Group, Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 24, Tulln A-3430, Austria.
authors.forename: Christoph
authors.initials: C
authors.lastname: Hoefer
authors.affiliation: Rhizosphere and Biogeochemistry Group, Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 24, Tulln A-3430, Austria.
authors.forename: Jakob
authors.initials: J
authors.lastname: Santner
authors.affiliation: Rhizosphere and Biogeochemistry Group, Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 24, Tulln A-3430, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Puschenreiter
authors.affiliation: Rhizosphere and Biogeochemistry Group, Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz-Strasse 24, Tulln A-3430, Austria.
authors.forename: Walter W
authors.initials: WW
authors.lastname: Wenzel
mesh_terms: D001673:Biodegradation, Environmental; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D008670:Metals / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D058441:Rhizosphere; D032108:Salix / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000378:metabolism*; D012995:Solubility; D013431:Sulfates / Q000378:metabolism*; D013455:Sulfur / Q000378:metabolism*
chemical_list: D008670:Metals; D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates; D013455:Sulfur; D010100:Oxygen