Anaerobic microbial remobilization of toxic metals coprecipitated with iron oxide

Francis, A.J.; Dodge, Cleveland J.

doi:10.1021/es00073a013

Cited by 111 publications

(62 citation statements)

References 14 publications

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“…Clay minerals such as illite have large surface areas, and tend to adsorb inorganic and organic contaminants (31). Dissolution of clay minerals by bacteria would mobilize these contaminants in soils and aquifers (32).…”

Section: Discussionmentioning

confidence: 99%

Microbial Reduction of Structural Fe(III) in Illite and Goethite

Dong

Kukkadapu

Fredrickson

et al. 2003

Environ. Sci. Technol.

136

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Microbial reduction of Fe(III) in illite was studied to evaluate the possibility of microbial utilization of Fe(III) in sedimentary clays and to determine the effects of bioreduction on clay composition and structure. A subsurface bacterium (Shewanella putrefaciens CN32) and illite separates (<0.2 µm) from St. Peter Formation sandstone in Ogle County, IL, were used in laboratory experiments. Illite suspensions buffered at pH 7 with bicarbonate were inoculated with CN32 and provided with H 2 as an electron donor. In selected treatments, anthraquinone-2,6-disulfonate (AQDS), was included as an electron shuttle to facilitate the bioreduction. Fe(II) production in inoculated treatments was determined by extraction with 0.5 N HCl and compared to uninoculated controls to establish the extent of biological reduction. The resulting solids were characterized by Mo ¨ssbauer spectroscopy and scanning and transmission electron microscopy (SEM and TEM). The characterization of the starting illite material revealed that it contained a minor component of goethite (R-FeOOH) in addition to fibrous illite. The starting material (both goethite and illite) contained 6% (w/ w) total Fe, and 82% of the total Fe was Fe(III). Approximately 30% of total Fe was associated with goethite. At the end of a 30-day incubation, residual goethite and illite remained. The extent of reduction was much greater in the presence of AQDS (25%) than in its absence (0%). Modeling of Mo ¨ssbauer spectra of the bioreduced material indicated that both goethite and illite were reduced but to a different extent. Additionally, TEM evidence suggested that there was a dramatic change in illite morphology upon bioreduction from fibrous needles to plates. The ability of bacteria to utilize Fe(III) in illite has important implications for microbial functions and survival mechanisms, as well as many geological processes, in the subsurface.

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Section: Discussionmentioning

confidence: 99%

Microbial Reduction of Structural Fe(III) in Illite and Goethite

Dong

Kukkadapu

Fredrickson

et al. 2003

Environ. Sci. Technol.

136

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“…In this study, denitrification and Mn(IV) and Fe(III) reduction occurred simultaneously, and even simultaneous Fe(III) and SO 4 2− reduction was reported earlier (Postma and Jakobsen 1996;Vink 2002). Francis and Dodge (1990) showed that the release of metals from Fe-oxyhydroxides was facilitated by microbial action, and that dissolved Mn(II) facilitated this mechanism (Guha et al 2001). Fig.…”

Section: Floodplain Soil Reductionmentioning

confidence: 99%

“…Chromium(VI) can be reduced to Cr (III) by reactions with e.g., Fe (acting as a catalyst (Eary and Rai 1988)) and organic matter (Kozuh et al 2000). The direct relation between DOM and reduction rates of chromium was discussed by Buerge and Hug (1998), and Francis and Dodge (1990) showed that Cr was liberated by Fe-oxyhydroxides by-again-microbial action. Later, Guha et al (2001) showed that dissolved Mn(II) facilitates this mechanism.…”

Section: Heavy Metal Response To Reductionmentioning

confidence: 99%

Delayed immobilization of heavy metals in soils and sediments under reducing and anaerobic conditions; consequences for flooding and storage

Vink

Harmsen²,

Rijnaarts

2010

J Soils Sediments

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Purpose The consequences of permanent inundation and storage of flood plain soils and aquatic sediments on metal mobility were studied. The main goal was to quantify kinetic mobilisation processes in order to pinpoint the conditions that pose emission risks to groundwater and surface waters. Materials and methods Anaerobic pore water compositions of six existing depots, containing sediments from either aquatic or terrestrial origin, were measured to obtain reliable field references. Reduction experiments were performed with SOFIE cells, in which time-dynamic measurements of reducing pore waters were carried out at the reigning redox conditions. A parallel experiment tested the possibility if sulfide-deficiencies could be compensated by the reduction of added gypsum, thus increasing the available pool of reactive S. Model calculations were performed to distinguish between the thermodynamic and kinetic processes. Results and discussion Reduction of flood plain soils showed that dissolved organic matter (DOM) concentrations increased up to 7-fold over time, as a result of nutrient-mediated metabolic boost of organic matter degrading microorganisms. The association of metals to DOM increased significantly due to the loss of reactive Mn-oxide and Fe-oxyhydroxide sorption phases during reduction. DOM released metals only slowly, therefore kinetically hindering the phase shifting to stable metalsulfide precipitates. The observed effects lasted at least 10 months. In aquatic sediments, reduction rates of sulphates were six times faster, and the release of DOM occurred in lower amounts than in soils from terrestrial origin. It is shown that the addition of gypsum stimulates the formation of sulfides, thereby decreasing dissolved concentrations of most metals. On the short term however, the addition of gypsum leads to elevated concentrations of Zn and Cd due to increased electrolyte strength and subsequent Ca-metal-competition for sorption sites. This effect may be eliminated by not only adding an electron acceptor to the sediment, but also an effective donor, e.g., degradable organic matter. Conclusions For depots containing flood plain soils, the same kinetic mechanisms were observed as in the reduction experiments (elevated production of DOM and associated metals). It was concluded that reduction of flood plain soils may not necessarily result in efficient metal trapping. When storage is considered, a distinction should be made between sediments of terrestrial and aquatic origin.

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“…However, the stability of bioreduced uranium is a major concern because they can be readily reoxidized to the soluble U(VI)from. Metals associated with or coprecipitated with iron and manganese oxides and hydroxides can be remobilized due to reduction of host metal Fe 3+ and Mn 4+ (hydro)oxides either chemically or enzymatically (Stone and Morgan, 1987;Francis and Dodge, 1990) under anaerobic conditions.…”

Section: Immobilization Of Uraniummentioning

confidence: 99%