Transformation of zinc-concentrate in surface and subsurface environments: Implications for assessing zinc mobility/toxicity and choosing an optimal remediation strategy

Kwon, Man Jae,Boyanov, Maxim I.,Yang, Jung-Seok,Lee, Seunghak,Hwang, Yun Ho,Lee, Ju Yeon,Mishra, Bhoopesh,Kemner, Kenneth M. Elsevier Applied Science Publishers 2017 Environmental pollution Vol.226 No.-

<P><B>Abstract</B></P> <P>Zinc contamination in near- and sub-surface environments is a serious threat to many ecosystems and to public health. Sufficient understanding of Zn speciation and transport mechanisms is therefore critical to evaluating its risk to the environment and to developing remediation strategies. The geochemical and mineralogical characteristics of contaminated soils in the vicinity of a Zn ore transportation route were thoroughly investigated using a variety of analytical techniques (sequential extraction, XRF, XRD, SEM, and XAFS). Imported Zn-concentrate (ZnS) was deposited in a receiving facility and dispersed over time to the surrounding roadside areas and rice-paddy soils. Subsequent physical and chemical weathering resulted in dispersal into the subsurface. The species identified in the contaminated areas included Zn-sulfide, Zn-carbonate, other O-coordinated Zn-minerals, and Zn species bound to Fe/Mn oxides or clays, as confirmed by XAFS spectroscopy and sequential extraction. The observed transformation from S-coordinated Zn to O-coordinated Zn associated with minerals suggests that this contaminant can change into more soluble and labile forms as a result of weathering. For the purpose of developing a soil washing remediation process, the contaminated samples were extracted with dilute acids. The extraction efficiency increased with the increase of O-coordinated Zn relative to S-coordinated Zn in the sediment. This study demonstrates that improved understanding of Zn speciation in contaminated soils is essential for well-informed decision making regarding metal mobility and toxicity, as well as for choosing an appropriate remediation strategy using soil washing.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zn-concentrate accumulated in soils transformed to Zn species of various stability. </LI> <LI> Zn species at our site underwent the transformation from Zn sulfides → O-coordinated Zn. </LI> <LI> XAFS/sequential extraction showed a correlation between acid extractability and Zn speciation. </LI> <LI> Metal speciation enables a better assessment of metal mobility/toxicity and the choice of an optimal remediation strategy. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Graphical Abstract. Conceptual model of the apparent physical and geochemical processes controlling surface-subsurface partitioning of Zn in the study area.</P> <P>[DISPLAY OMISSION]</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.

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>

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.

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.

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>