Geochemical characteristics and microbial community composition in toxic metal-rich sediments contaminated with Au–Ag mine tailings

Kwon, Man Jae,Yang, Jung-Seok,Lee, Seunghak,Lee, Giehyeon,Ham, Baknoon,Boyanov, Maxim I.,Kemner, Kenneth M.,O’Loughlin, Edward J. Elsevier 2015 Journal of hazardous materials Vol.296 No.-

<P><B>Abstract</B></P> <P>The effects of extreme geochemical conditions on microbial community composition were investigated for two distinct sets of sediment samples collected near weathered mine tailings. One set (SCH) showed extraordinary geochemical characteristics: As (6.7–11.5%), Pb (1.5–2.1%), Zn (0.1–0.2%), and pH (3.1–3.5). The other set (SCL) had As (0.3–1.2%), Pb (0.02–0.22%), and Zn (0.01–0.02%) at pH 2.5–3.1. The bacterial communities in SCL were clearly different from those in SCH, suggesting that extreme geochemical conditions affected microbial community distribution even on a small spatial scale. The clones identified in SCL were closely related to acidophilic bacteria in the taxa <I>Acidobacterium</I> (18%), <I>Acidomicrobineae</I> (14%), and <I>Leptospirillum</I> (10%). Most clones in SCH were closely related to <I>Methylobacterium</I> (79%) and <I>Ralstonia</I> (19%), both well-known metal-resistant bacteria. Although total As was extremely high, over 95% was in the form of scorodite (FeAsO<SUB>4</SUB>·2H<SUB>2</SUB>O). Acid-extractable As was only ∼118 and ∼14mgkg<SUP>−1</SUP> in SCH and SCL, respectively, below the level known to be toxic to bacteria. Meanwhile, acid-extractable Pb and Zn in SCH were above toxic concentrations. Because As was present in an oxidized, stable form, release of Pb and/or Zn (or a combination of toxic metals in the sediment) from the sediment likely accounts for the differences in microbial community structure. The results also suggest that care should be taken when investigating mine tailings, because large differences in chemical/biological properties can occur over small spatial scales.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Over 95% of solid-phase As was in the form of scorodite (FeAsO<SUB>4</SUB>·2H<SUB>2</SUB>O). </LI> <LI> <I>Methylobacterium</I>/<I>Ralstonia</I> were predominant in sediments with high levels of toxic metals. </LI> <LI> Extreme geochemical conditions affected microbial community distribution. </LI> <LI> Pb and/or Zn released from the sediment might cause the differences in microbial community. </LI> </UL> </P>

Application of an in-situ soil sampler for assessing subsurface biogeochemical dynamics in a diesel-contaminated coastal site during soil flushing operations

Kwon, Man Jae,O'Loughlin, Edward J.,Ham, Baknoon,Hwang, Yunho,Shim, Moojoon,Lee, Soonjae Elsevier 2018 Journal of environmental management Vol.206 No.-

<P><B>Abstract</B></P> <P>Subsurface biogeochemistry and contaminant dynamics during the remediation of diesel-contamination by in-situ soil flushing were investigated at a site located in a coastal region. An in-situ sampler containing diesel-contaminated soils separated into two size fractions (<0.063- and <2-mm) was utilized in two monitoring wells: DH1 (located close to the injection and extraction wells for in-situ soil flushing) and DH2 (located beyond sheet piles placed to block the transport of leaked diesel). Total petroleum hydrocarbon (TPH) concentrations and biogeochemical properties were monitored both in soil and groundwater for six months. A shift occurred in the groundwater type from Ca-HCO<SUB>3</SUB> to Na-Cl due to seawater intrusion during intense pumping, while the concentrations of Ni, Cu, Co, V, Cr, and Se increased substantially following surfactant (TWEEN 80) injection. The in-situ sampler with fine particles was more sensitive to variations in conditions during the remedial soil flushing process. In both wells, soil TPH concentrations in the <0.063-mm fraction were much higher than those in the <2-mm fraction. Increases in soil TPH in DH1 were consistent with the expected outcomes following well pumping and surfactant injection used to enhance TPH extraction. However, the number of diesel-degrading microorganisms decreased after surfactant injection. 16S-rRNA gene-based analysis also showed that the community composition and diversity depended on both particle size and diesel contamination. The multidisciplinary approach to the contaminated site assessments showed that soil flushing with surfactant enhanced diesel extraction, but negatively impacted in-situ diesel biodegradation as well as groundwater quality. The results also suggest that the in-situ sampler can be an effective monitoring tool for subsurface biogeochemistry as well as contaminant dynamics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> In-situ samplers well reflected biogeochemical dynamics during in-situ soil flushing. </LI> <LI> In-situ samplers with fine particles showed contaminant dynamics much sensitively. </LI> <LI> Soil particle sizes and TPH concentrations impact community diversity and composition. </LI> <LI> Soil-flushing negatively impacted diesel biodegradation as well as groundwater quality. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Bioreduction of Hydrogen Uranyl Phosphate: Mechanisms and U(IV) Products

Rui, Xue,Kwon, Man Jae,O’Loughlin, Edward J.,Dunham-Cheatham, Sarrah,Fein, Jeremy B.,Bunker, Bruce,Kemner, Kenneth M.,Boyanov, Maxim I. American Chemical Society 2013 Environmental science & technology Vol.47 No.11

<P>The mobility of uranium (U) in subsurface environments is controlled by interrelated adsorption, redox, and precipitation reactions. Previous work demonstrated the formation of nanometer-sized hydrogen uranyl phosphate (abbreviated as HUP) crystals on the cell walls of <I>Bacillus subtilis</I>, a non-U<SUP>VI</SUP>-reducing, Gram-positive bacterium. The current study examined the reduction of this biogenic, cell-associated HUP mineral by three dissimilatory metal-reducing bacteria, <I>Anaeromyxobacter dehalogenans</I> strain K, <I>Geobacter sulfurreducens</I> strain PCA, and <I>Shewanella putrefaciens</I> strain CN-32, and compared it to the bioreduction of abiotically formed and freely suspended HUP of larger particle size. Uranium speciation in the solid phase was followed over a 10- to 20-day reaction period by X-ray absorption fine structure spectroscopy (XANES and EXAFS) and showed varying extents of U<SUP>VI</SUP> reduction to U<SUP>IV</SUP>. The reduction extent of the same mass of HUP to U<SUP>IV</SUP> was consistently greater with the biogenic than with the abiotic material under the same experimental conditions. A greater extent of HUP reduction was observed in the presence of bicarbonate in solution, whereas a decreased extent of HUP reduction was observed with the addition of dissolved phosphate. These results indicate that the extent of U<SUP>VI</SUP> reduction is controlled by dissolution of the HUP phase, suggesting that the metal-reducing bacteria transfer electrons to the dissolved or bacterially adsorbed U<SUP>VI</SUP> species formed after HUP dissolution, rather than to solid-phase U<SUP>VI</SUP> in the HUP mineral. Interestingly, the bioreduced U<SUP>IV</SUP> atoms were not immediately coordinated to other U<SUP>IV</SUP> atoms (as in uraninite, UO<SUB>2</SUB>) but were similar in structure to the phosphate-complexed U<SUP>IV</SUP> species found in ningyoite [CaU(PO<SUB>4</SUB>)<SUB>2</SUB>·H<SUB>2</SUB>O]. This indicates a strong control by phosphate on the speciation of bioreduced U<SUP>IV</SUP>, expressed as inhibition of the typical formation of uraninite under phosphate-free conditions.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2013/esthag.2013.47.issue-11/es305258p/production/images/medium/es-2012-05258p_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es305258p'>ACS Electronic Supporting Info</A></P>

전자공여체와 황산염 이용 토착미생물에 의한 침철석(α-FeOOH) 환원 연구

권만재,양중석,심무준,이승학,Maxim Boyanov,Kenneth Kemner,Edward O'Loughlin 한국지하수토양환경학회 2014 지하수토양환경 Vol.19 No.1

To better understand dissimilatory iron and sulfate reduction (DIR and DSR) by subsurface microorganisms, we investigated the effects of sulfate and electron donors on the microbial goethite (α-FeOOH) reduction. Batch systems were created 1) with acetate or glucose (donor), 2) with goethite and sulfate (acceptor), and 3) with aquifer sediment (microbial source). With 0.2 mM sulfate, goethite reduction coupled with acetate oxidation was limited. However, with 10 mM sulfate, 8 mM goethite reduction occurred with complete sulfate reduction and x-ray absorption fine-structure analysis indicated the formation of iron sulfide. This suggests that goethite reduction was due to the sulfide species produced by DSR bacteria rather than direct microbial reaction by DIR bacteria. Both acetate and glucose promoted goethite reduction. The rate of goethite reduction was faster with glucose, while the extent of goethite reduction was higher with acetate. Sulfate reduction (10 mM) occurred only with acetate. The results suggest that glucose-fermenting bacteria rapidly stimulated goethite reduction, but acetate-oxidizing DSR bacteria reduced goethite indirectly by producing sulfides. This study suggests that the availability of specific electron donor and sulfate significantly influence microbial community activities as well as goethite transformation, which should be considered for the bioremediation of contaminated environments.

The transport behavior of As, Cu, Pb, and Zn during electrokinetic remediation of a contaminated soil using electrolyte conditioning

Yang, Jung-Seok,Kwon, Man Jae,Choi, Jaeyoung,Baek, Kitae,O’Loughlin, Edward J. Elsevier 2014 CHEMOSPHERE - Vol.117 No.-

<P><B>Abstract</B></P> <P>Electrokinetic remediation (also known as electrokinetics) is a promising technology for removing metals from fine-grained soils. However, few studies have been conducted regarding the transport behavior of multi-metals during electrokinetics. We investigated the transport of As, Cu, Pb, and Zn from soils during electrokinetics, the metal fractionation before and after electrokinetics, the relationships between metal transport and fractionation, and the effects of electrolyte conditioning. The main transport mechanisms of the metals were electroosmosis and electromigration during the first two weeks and electromigration during the following weeks. The direction of electroosmotic flow was from the anode to the cathode, and the metals in the dissolved and reducible-oxides fractions were transported to the anode or cathode by electromigration according to the chemical speciation of the metal ions in the pore water. Moreover, a portion of the metals that were initially in the residual fraction transitioned to the reducible and soluble fractions during electrokinetic treatment. However, this alteration was slow and resulted in decreasing metal removal rates as the electrokinetic treatment progressed. In addition, the use of NaOH, H<SUB>3</SUB>PO<SUB>4</SUB>, and Na<SUB>2</SUB>SO<SUB>4</SUB> as electrolytes resulted in conditions that favored the precipitation of metal hydroxides, phosphates, and sulfates in the soil. These results demonstrated that metal removal was affected by the initial metal fractionation, metal speciation in the pore solution, and the physical–chemical parameters of the electrolytes, such as pH and electrolyte composition. Therefore, the treatment time, use of chemicals, and energy consumption could be reduced by optimizing pretreatment and by choosing appropriate electrolytes for the target metals.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Metal fractionation during EK was changed by a suite of physical–chemical processes. </LI> <LI> Metal transport during EK was controlled by the metal speciation/fractionation. </LI> <LI> Electrolyte-conditioning for EK enhanced selectivity in metal removal. </LI> <LI> Simultaneous removal of multi-metals was not effective in single-electrolyte conditioning. </LI> </UL> </P>

Spatial and Vertical Distribution of Sb and Toxic Metals Near a Sb Refinery and a Shooting Range and Their Effects on Indigenous Microorganisms

( Soo-chan Park ),( Han-suk Kim ),( Junggil Lee ),( Maxim I. Boyanov ),( Edward J. O’loughlin ),( Kenneth M. Kemner ),( Man Jae Kwon ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

As the ninth-most mined metal worldwide, a large quantity of antimony (Sb) and Sb-contained compounds have been released into the environment. Sources of Sb release include abrasion from brake linings, use as flame retardants, plastic production, mining, refining and shooting activities. Though the ecotoxicity of Sb is not well known, Sb(III) compounds are generally considered to be more toxic and mobile than Sb(V), similar to that of As. Therefore, distribution, speciation, toxicity and bioavailability of Sb in various environmental compartments are considered to be primary controlling factors for human and ecosystem health. To investigate distribution and biogeochemical characteristics of Sb and other toxic metals in contaminated soils, we collected three different types of Sb-contaminated soil samples in South Korea: 1) Sb refinery, 2) Sb waste landfill site, and 3) military shooting range. Soil samples adjacent to the Sb refinery and the Sb waste landfill site generally represented much higher Sb concentration than the shooting rage. X-ray absorption fine-structure (XAFS) analysis showed that Sb was mainly in Sb(V) valence state and present as tripuhyite(FeSbO4) in sediments near refinery and landfill site. In the shooting range, multiple contamination of heavy metals from bullet was observed. Microbial population using most probable numbers (MPN) didn’t show a significant difference between sites (~10⁶ cells/g soil). 16S rRNA gene-based metagenomic analysis were also conducted to characterize the microbial community compositions in the sites. We will discuss the possible effects of the toxic metals on the indigenous microorganisms.

전자공여체와 황산염 이용 토착미생물에 의한 침철석(α-FeOOH) 환원 연구

Kwon, Man Jae,Yang, Jung-Seok,Shim, Moo Joon,Lee, Seunghak,Boyanov, Maxim,Kemner, Kenneth,O'Loughlin, Edward 한국지하수토양환경학회 2014 지하수토양환경 Vol.19 No.1

To better understand dissimilatory iron and sulfate reduction (DIR and DSR) by subsurface microorganisms, we investigated the effects of sulfate and electron donors on the microbial goethite (${\alpha}$-FeOOH) reduction. Batch systems were created 1) with acetate or glucose (donor), 2) with goethite and sulfate (acceptor), and 3) with aquifer sediment (microbial source). With 0.2 mM sulfate, goethite reduction coupled with acetate oxidation was limited. However, with 10 mM sulfate, 8 mM goethite reduction occurred with complete sulfate reduction and x-ray absorption fine-structure analysis indicated the formation of iron sulfide. This suggests that goethite reduction was due to the sulfide species produced by DSR bacteria rather than direct microbial reaction by DIR bacteria. Both acetate and glucose promoted goethite reduction. The rate of goethite reduction was faster with glucose, while the extent of goethite reduction was higher with acetate. Sulfate reduction (10 mM) occurred only with acetate. The results suggest that glucose-fermenting bacteria rapidly stimulated goethite reduction, but acetate-oxidizing DSR bacteria reduced goethite indirectly by producing sulfides. This study suggests that the availability of specific electron donor and sulfate significantly influence microbial community activities as well as goethite transformation, which should be considered for the bioremediation of contaminated environments.