title: Influence of arsenate adsorption to ferrihydrite, goethite, and boehmite on the kinetics of arsenate reduction by Shewanella putrefaciens strain CN-32.
abstract: The kinetics of As(V) reduction by Shewanella putrefaciens strain CN-32 was investigated in suspensions of 0.2, 2, or 20 g L(-1) ferrihydrite, goethite, or boehmite at low As (10 μM) and lactate (25 μM) concentrations. Experimental data were compared with model predictions based on independently determined sorption isotherms and rates of As(V) desorption, As(III) adsorption, and microbial reduction of dissolved As(V), respectively. The low lactate concentration was chosen to prevent significant Fe(III) reduction, but still allowing complete As(V) reduction. Reduction of dissolved As(V) followed first-order kinetics with a 3 h half-life of As(V). Addition of mineral sorbents resulted in pronounced decreases in reduction rates (32-1540 h As(V) half-life). The magnitude of this effect increased with increasing sorbent concentration and sorption capacity (goethite < boehmite < ferrihydrite). The model consistently underestimated the concentrations of dissolved As(V) and the rates of microbial As(V) reduction after addition of S. putrefaciens (∼5 × 10(9) cells mL(-1)), suggesting that attachment of S. putrefaciens cells to oxide mineral surfaces promoted As(V) desorption and thereby facilitated As(V) reduction. The interplay between As(V) sorption to mineral surfaces and bacterially induced desorption may thus be critical in controlling the kinetics of As reduction and release in reducing soils and sediments.
authors.affiliation: Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, CHN, CH-8092 Zurich, Switzerland. jenhow.huang@env.ethz.ch
authors.forename: Jen-How
authors.initials: JH
authors.lastname: Huang
authors.forename: Andreas
authors.initials: A
authors.lastname: Voegelin
authors.forename: Silvina A
authors.initials: SA
authors.lastname: Pombo
authors.forename: Anna
authors.initials: A
authors.lastname: Lazzaro
authors.forename: Josef
authors.initials: J
authors.lastname: Zeyer
authors.forename: Ruben
authors.initials: R
authors.lastname: Kretzschmar
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry; D000537:Aluminum Oxide / Q000737:chemistry; D001149:Arsenates / Q000737:chemistry / Q000378:metabolism*; D004785:Environmental Pollutants / Q000378:metabolism*; D005290:Ferric Compounds / Q000737:chemistry; D058085:Iron Compounds / Q000737:chemistry; D007700:Kinetics; D008903:Minerals / Q000737:chemistry; D010084:Oxidation-Reduction; D020614:Shewanella putrefaciens / Q000378:metabolism*
chemical_list: D001149:Arsenates; D004785:Environmental Pollutants; D005290:Ferric Compounds; D058085:Iron Compounds; D008903:Minerals; C094886:goethite; D000536:Aluminum Hydroxide; C069471:aluminum oxide hydroxide; C092844:ferric oxyhydroxide; D000537:Aluminum Oxide; C025657:arsenic acid