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Kastury F, Besedin J, Betts AR, Asamoah R, Herde C, Netherway P, Tully J, Scheckel KG, Juhasz AL. Arsenic, cadmium, lead, antimony bioaccessibility and relative bioavailability in legacy gold mining waste. J Hazard Mater 2024; 469:133948. [PMID: 38493633 PMCID: PMC11097331 DOI: 10.1016/j.jhazmat.2024.133948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 03/19/2024]
Abstract
Bioaccessibility and relative bioavailability of As, Cd, Pb and Sb was investigated in 30 legacy gold mining wastes (calcine sands, grey battery sands, tailings) from Victorian goldfields (Australia). Pseudo-total As concentration in 29 samples was 1.45-148-fold higher than the residential soil guidance value (100 mg/kg) while Cd and Pb concentrations in calcine sands were up to 2.4-fold and 30.1-fold higher than the corresponding guidance value (Cd: 20 mg/kg and Pb: 300 mg/kg). Five calcine sands exhibited elevated Sb (31.9-5983 mg/kg), although an Australian soil guidance value is currently unavailable. Arsenic bioaccessibility (n = 30) and relative bioavailability (RBA; n = 8) ranged from 6.10-77.6% and 10.3-52.9% respectively. Samples containing > 50% arsenopyrite/scorodite showed low As bioaccessibility (<20.0%) and RBA (<15.0%). Co-contaminant RBA was assessed in 4 calcine sands; Pb RBA ranged from 73.7-119% with high Pb RBA associated with organic and mineral sorbed Pb and, lower Pb RBA observed in samples containing plumbojarosite. In contrast, Cd RBA ranged from 55.0-67.0%, while Sb RBA was < 5%. This study highlights the importance of using multiple lines of evidence during exposure assessment and provides valuable baseline data for co-contaminants associated with legacy gold mining activities.
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Affiliation(s)
- Farzana Kastury
- Future Industries Institute, STEM, University of South Australia, SA, Australia.
| | - Julie Besedin
- Future Industries Institute, STEM, University of South Australia, SA, Australia; School of Science, STEM, RMIT University, Victoria, Australia
| | - Aaron R Betts
- United States Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Land Remediation and Technology Division, Cincinnati, OH, USA
| | - Richmond Asamoah
- Future Industries Institute, STEM, University of South Australia, SA, Australia
| | - Carina Herde
- South Australian Health and Medical Research Institute, Adelaide 5086, Australia
| | - Pacian Netherway
- EPA Science, Environment Protection Authority Victoria, Centre for Applied Sciences, Ernest Jones Drive, Macleod, Melbourne, Victoria 3085, Australia
| | - Jennifer Tully
- United States Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Water Infrastructure Division, Cincinnati, OH, USA
| | - Kirk G Scheckel
- United States Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Land Remediation and Technology Division, Cincinnati, OH, USA
| | - Albert L Juhasz
- Future Industries Institute, STEM, University of South Australia, SA, Australia
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Sowers TD, Blackmon MD, Betts AR, Jerden ML, Scheckel KG, Bradham KD. Potassium jarosite seeding of soils decreases lead and arsenic bioaccessibility: A path toward concomitant remediation. Proc Natl Acad Sci U S A 2023; 120:e2311564120. [PMID: 38048468 PMCID: PMC10723135 DOI: 10.1073/pnas.2311564120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 10/23/2023] [Indexed: 12/06/2023] Open
Abstract
Soils are common sources of metal(loid) contaminant exposure globally. Lead (Pb) and arsenic (As) are of paramount concern due to detrimental neurological and carcinogenic health effects, respectively. Pb and/or As contaminated soils require remediation, typically leading to excavation, a costly and environmentally damaging practice of removing soil to a central location (e.g., hazardous landfill) that may not be a viable option in low-income countries. Chemical remediation techniques may allow for in situ conversion of soil contaminants to phases that are not easily mobilized upon ingestion; however, effective chemical remediation options are limited. Here, we have successfully tested a soil remediation technology using potted soils that relies on converting soil Pb and As into jarosite-group minerals, such as plumbojarosite (PLJ) and beudantite, possessing exceptionally low bioaccessibility [i.e., solubility at gastric pH conditions (pH 1.5 to 3)]. Across all experiments conducted, all new treatment methods successfully promoted PLJ and/or beudantite conversion, resulting in a proportional decrease in Pb and As bioaccessibility. Increasing temperature resulted in increased conversion to jarosite-group minerals, but addition of potassium (K) jarosite was most critical to Pb and As bioaccessibility decreases. Our methods of K-jarosite treatment yielded <10% Pb and As bioaccessibility compared to unamended soil values of approximately 70% and 60%, respectively. The proposed treatment is a rare dual remediation option that effectively treats soil Pb and As such that potential exposure is considerably reduced. Research presented here lays the foundation for ongoing field application.
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Affiliation(s)
- Tyler D. Sowers
- Center for Environmental Measurement and Modeling, Office of Research and Development, United States Environmental Protection Agency, Durham, NC27711
| | - Matthew D. Blackmon
- Center for Environmental Measurement and Modeling, Office of Research and Development, United States Environmental Protection Agency, Durham, NC27711
| | - Aaron R. Betts
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH45268
| | | | - Kirk G. Scheckel
- Center for Environmental Solutions & Emergency Response, Office of Research and Development, United States Environmental Protection Agency, Cincinnati, OH45268
| | - Karen D. Bradham
- Center for Environmental Measurement and Modeling, Office of Research and Development, United States Environmental Protection Agency, Durham, NC27711
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Betts AR, Siebecker MG, Elzinga EJ, Luxton TP, Scheckel KG, Sparks DL. Influence of clay mineral weathering on green rust formation at iron-reducing conditions. Geochim Cosmochim Acta 2023; 350:46-56. [PMID: 37469621 PMCID: PMC10355121 DOI: 10.1016/j.gca.2023.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Green rusts (GR) are important drivers for trace metal and nutrient cycling in suboxic environments. We investigated whether green rusts would incorporate aluminum (Al) or other elements from naturally-formed clay minerals containing easily-weatherable clay minerals (e.g. mica, interlayered clays). We isolated the clay minerals from a Matapeake silt loam soil by removal of silt and sand, organic matter, and reducible oxides to study mechanisms of interaction between Fe(II) and soil-sourced clay minerals. We conducted batch Fe(II) sorption experiments at multiple near-neutral pHs (6.5-7.5) and reaction times (2 h-365 days). Mineral transformations were characterized by selective extractions, X-ray diffraction (XRD), and Fe X-ray absorption spectroscopy (XAS) analyzed by shell-fitting and linear combination fitting (LCF) with natural and synthetic standards. Clay mineral fraction contained a mixture of quartz, kaolinite, interlayered vermiculite, mica, and chlorite with significant structural Fe (2.6% wt). Uptake of Fe(II) increased with pH and kinetics were rapid until 5 days, followed by slow continuous Fe(II) uptake. Citrate-bicarbonate desorption kinetics from Fe(II) sorbed clay released more Al and silicon (Si) compared with unreacted soil clay fraction whereas magnesium (Mg) and potassium (K) were unaffected. Citrate-bicarbonate extracted Fe contained more Fe(II) than an ideal GR with an Fe(II)/Fe(III) molar ratio of 5.50. Analysis of the Fe EXAFS by both LCF and shell fitting was best modeled as a combination of Fe(III)-clay reduction to Fe(II) and precipitation of GR and Fe(II)-Al LDH. After 7 days of Fe(II) sorption, LCF identified 55.2% total Fe in clay, 33.4% GR(Cl) and 11.4% Fe(II)-Al LDH. These results provide novel evidence of Fe(II)-Al LDHs precipitating on naturally-formed soil clay minerals as a minor phase to GR. The geochemical implications are that GRs formed in soils and sediments should be considered to have Al and Si as well as Mg substitutions affecting their structure and reactivity.
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Affiliation(s)
- Aaron R. Betts
- Department of Plant and Soil Science, University of Delaware, 221 Academy St, Newark, DE 19716, USA
| | - Matthew G. Siebecker
- Department of Plant and Soil Science, University of Delaware, 221 Academy St, Newark, DE 19716, USA
| | - Evert J. Elzinga
- Department of Earth and Environmental Sciences, Rutgers University, 101 Warren St, Newark, NJ 07102, USA
| | - Todd P. Luxton
- Office of Research & Development, U.S. Environmental Protection Agency, 5995 Center Hill Ave, Cincinnati, OH 45224, USA
| | - Kirk G. Scheckel
- Office of Research & Development, U.S. Environmental Protection Agency, 5995 Center Hill Ave, Cincinnati, OH 45224, USA
| | - Donald L. Sparks
- Department of Plant and Soil Science, University of Delaware, 221 Academy St, Newark, DE 19716, USA
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Sowers TD, Wani RP, Coward EK, Fischel MHH, Betts AR, Douglas TA, Duckworth OW, Sparks DL. Spatially Resolved Organomineral Interactions across a Permafrost Chronosequence. Environ Sci Technol 2020; 54:2951-2960. [PMID: 32023050 DOI: 10.1021/acs.est.9b06558] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Permafrost contains a large (1700 Pg C) terrestrial pool of organic matter (OM) that is susceptible to degradation as global temperatures increase. Of particular importance is syngenetic Yedoma permafrost containing high OM content. Reactive iron phases promote stabilizing interactions between OM and soil minerals and this stabilization may be of increasing importance in permafrost as the thawed surface region ("active layer") deepens. However, there is limited understanding of Fe and other soil mineral phase associations with OM carbon (C) moieties in permafrost soils. To elucidate the elemental associations involved in organomineral complexation within permafrost systems, soil cores spanning a Pleistocene permafrost chronosequence (19,000, 27,000, and 36,000 years old) were collected from an underground tunnel near Fairbanks, Alaska. Subsamples were analyzed via scanning transmission X-ray microscopy-near edge X-ray absorption fine structure spectroscopy at the nano- to microscale. Amino acid-rich moieties decreased in abundance across the chronosequence. Strong correlations between C and Fe with discrete Fe(III) or Fe(II) regions selectively associated with specific OM moieties were observed. Additionally, Ca coassociated with C through potential cation bridging mechanisms. Results indicate Fe(III), Fe(II), and mixed valence phases associated with OM throughout diverse permafrost environments, suggesting that organomineral complexation is crucial to predict C stability as permafrost systems warm.
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Affiliation(s)
- Tyler D Sowers
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
- Office of Research and Development, United States Environmental Protection Agency, Research Triangle Park, Durham, North Carolina 27711, United States
| | - Rucha P Wani
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
| | - Elizabeth K Coward
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
| | - Matthew H H Fischel
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
| | - Aaron R Betts
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
| | - Thomas A Douglas
- U.S. Army Cold Regions Research & Engineering Laboratory, 9th Avenue, Building 4070, Fort Wainwright, Fairbanks, 99703 Alaska, United States
| | - Owen W Duckworth
- Department of Crop and Soil Sciences, North Carolina State University, 101 Derieux Street, Campus Box 7620, Raleigh, North Carolina 26795, United States
| | - Donald L Sparks
- Delaware Environmental Institute, Department of Plant and Soil Sciences, University of Delaware, Newark, Delaware 19716-7310, United States
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Karna RR, Noerpel M, Betts AR, Scheckel KG. Lead and Arsenic Bioaccessibility and Speciation as a Function of Soil Particle Size. J Environ Qual 2017; 46:1225-1235. [PMID: 29293839 PMCID: PMC5868743 DOI: 10.2134/jeq2016.10.0387] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 01/12/2017] [Indexed: 05/04/2023]
Abstract
Bioavailability research of soil metals has advanced considerably from default values to validated in vitro bioaccessibility (IVBA) assays for site-specific risk assessment. Previously, USEPA determined that the soil-size fraction representative of dermal adherence and consequent soil ingestion was <250 μm. This size fraction was widely used in testing efforts for both in vivo and in vitro experiments. However, recent studies indicate the <150-μm size fraction better represents the particle size that adheres to skin for potential ingestion. At issue is the relevance of validated in vivo and in vitro methods developed with <250 μm moving to the <150-μm fraction. The objectives of this study were to investigate <250-μm versus <150-μm particle size and particle size groups for evaluating lead (Pb) and arsenic (As) IVBA and speciation. Soils with different properties were homogenized, oven dried, and sieved: <250 to > 150, <150 to >75, <75 to >38, and <38 μm. Sieved versus ground subsamples of <250-μm and <150-μm bulk soils were also used for IVBA and synchrotron-based Pb and As speciation. Although we observed an increase in total and IVBA-extractable Pb and As with decreased soil particle size, changes in %IVBA of Pb and As (dependent on the ratio extractable:total) remained consistent in all of the tested soils. No significant changes in Pb and As speciation were observed across the soil fractions. The results suggest that using the more relevant <150-μm fraction will not undermine currently validated IVBA protocols in future bioavailability studies.
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Affiliation(s)
- Ranju R. Karna
- Research Participant, Oak Ridge Institute of Science and Education, National Risk Management Research Laboratory-Land Remediation and Pollution Control Division, 5995 Center Hill Avenue, Cincinnati, OH 45224-1701
| | - Matt Noerpel
- Research Participant, Oak Ridge Institute of Science and Education, National Risk Management Research Laboratory-Land Remediation and Pollution Control Division, 5995 Center Hill Avenue, Cincinnati, OH 45224-1701
| | - Aaron R. Betts
- Research Participant, Oak Ridge Institute of Science and Education, National Risk Management Research Laboratory-Land Remediation and Pollution Control Division, 5995 Center Hill Avenue, Cincinnati, OH 45224-1701
- Graduate Student, Department of Soil and Plant Sciences, University of Delaware, 221 Academy St., Newark, DE-19711
| | - Kirk G. Scheckel
- Senior Research Soil Scientist, United States Environmental Protection Agency, National Risk Management Research Laboratory-Land Remediation and Pollution Control Division, 5995 Center Hill Avenue, Cincinnati, OH 45224-1701
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Juhasz AL, Scheckel KG, Betts AR, Smith E. Predictive Capabilities of in Vitro Assays for Estimating Pb Relative Bioavailability in Phosphate Amended Soils. Environ Sci Technol 2016; 50:13086-13094. [PMID: 27934280 DOI: 10.1021/acs.est.6b04059] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In this study, the in vitro bioaccessibility (IVBA) of lead (Pb) in phosphate-amended Pb-contaminated soil was assessed using a variety of IVBA assays with an overarching aim of determining whether changes in Pb IVBA were congruent to those observed for Pb relative bioavailability (RBA) determined using an in vivo mouse assay. Amending soil with phosphoric acid or rock phosphate resulted in changes in Pb speciation, however, varying Pb IVBA results were obtained depending on the methodology utilized. In addition, IVBA assays influenced Pb speciation as a consequence of interactions between dissolved Pb and unreacted phosphate arising from the amendment or from assay constituents. When the relationship between Pb RBA and IVBA was assessed, a comparison of treatment effect ratios (Pb RBA or IVBA in treated soil divided by Pb RBA or IVBA for untreated soil) provided the best in vivo-in vitro correlation particular for SBRC (r2 = 0.83) and IVG (r2 = 0.89) intestinal extraction. For these assays, the slope of the lines of best fit were close to 1 (1.12, 0.82; SBRC, IVG intestinal extraction respectively) with small y-intercepts (0.09, 0.08 respectively) indicating that the efficacy of phosphate amendments for reducing Pb RBA may be predicted using IVBA assays.
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Affiliation(s)
- Albert L Juhasz
- Future Industries Institute, University of South Australia , Mawson Lakes, South Australia 5095, Australia
| | - Kirk G Scheckel
- U.S. Environmental Protection Agency, National Risk Management Research Laboratory, Land Remediation and Pollution Control Division, Cincinnati, Ohio 45224-1701, United States
| | - Aaron R Betts
- U.S. Environmental Protection Agency, National Risk Management Research Laboratory, Land Remediation and Pollution Control Division, Cincinnati, Ohio 45224-1701, United States
- Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37831, United States
| | - Euan Smith
- Future Industries Institute, University of South Australia , Mawson Lakes, South Australia 5095, Australia
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Ollson CJ, Smith E, Scheckel KG, Betts AR, Juhasz AL. Assessment of arsenic speciation and bioaccessibility in mine-impacted materials. J Hazard Mater 2016; 313:130-137. [PMID: 27060218 DOI: 10.1016/j.jhazmat.2016.03.090] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 03/04/2016] [Accepted: 03/30/2016] [Indexed: 06/05/2023]
Abstract
Mine-impacted materials were collected from Victoria, Australia and categorized into three source materials; tailings (n=35), calcinated (n=10) and grey slimes (n=5). Arsenic (As) concentrations in these materials varied over several orders of magnitude (30-47,000mgkg(-1)), with median concentrations of 500, 10,800 and 1500mgkg(-1), respectively. When As bioaccessibility was assessed using the Solubility Bioaccessibility Research Consortium (SBRC) assay, As bioaccessibility ranged between 4 and 90%, with mean gastric phase values of 30%, 49% and 82% for tailings, calcinated and grey slimes, respectively. An analysis of variance (ANOVA) determined that As bioaccessibility was significantly different (P<0.05) between source materials. This was due to differences in As mineralogy, soil particle size as well as the concentration and nature of Fe present. X-ray Absorption Near Edge Structure (XANES) analysis identified arseniosiderite, yukonite, realgar, loellingite and mineral sorbed arsenate species in mine-impacted materials. Despite differences in physicochemical properties, 'mine wastes' are often reported under a generic descriptor. Outcomes from this research highlight that variability in As bioaccessibility can be prescribed to As mineralogy and matrix physicochemical properties, while categorizing samples into sub-groups can provide some notional indication of potential exposure.
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Affiliation(s)
- Cameron J Ollson
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
| | - Euan Smith
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Kirk G Scheckel
- United States Environmental Protection Agency, National Risk Management Research Laboratory, Land Remediation and Pollution Control Division, Cincinnati, OH 45224-1701 USA
| | - Aaron R Betts
- United States Environmental Protection Agency, National Risk Management Research Laboratory, Land Remediation and Pollution Control Division, Cincinnati, OH 45224-1701 USA
| | - Albert L Juhasz
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
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Mele E, Donner E, Juhasz AL, Brunetti G, Smith E, Betts AR, Castaldi P, Deiana S, Scheckel KG, Lombi E. In Situ Fixation of Metal(loid)s in Contaminated Soils: A Comparison of Conventional, Opportunistic, and Engineered Soil Amendments. Environ Sci Technol 2015; 49:13501-9. [PMID: 26457447 DOI: 10.1021/acs.est.5b01356] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This study aimed to assess and compare the in vitro and in vivo bioaccessibility/bioavailability of As and Pb in a mining contaminated soil (As, 2267 mg kg(-1); Pb, 1126 mg kg(-1)), after the addition of conventional (phosphoric acid), opportunistic [water treatment residues (WTRs)], and engineered [nano- and microscale zero valent iron (ZVI)] amendments. Phosphoric acid was the only amendment that could significantly decrease Pb bioaccessibility with respect to untreated soil (41 and 47% in the gastric phase and 2.1 and 8.1% in the intestinal phases, respectively), giving treatment effect ratios (TERs, the bioaccessibility in the amended soil divided by the bioaccessibility in the untreated soil) of 0.25 and 0.87 in the gastric and intestinal phase, respectively. The in vivo bioavailability of Pb decreased in the phosphate treatment relative to the untreated soil (6 and 24%, respectively), and also in the Fe WTR 2% (12%) and nZVI-2 (13%) treatments. The ZVI amendments caused a decrease in As bioaccessibility, with the greatest decrease in the nZVI2-treated soil (TERs of 0.59 and 0.64 in the gastric and intestinal phases, respectively). Arsenic X-ray absorption near-edge spectroscopy analysis indicated that most of the As in the untreated soil was present as As(V) associated with Fe mineral phases, whereas in the treated soil, the proportion of arsenosiderite increased. Arsenite was present only as a minor species (3-5%) in the treated soils, with the exception of an nZVI treatment [∼14% of As(III)], suggesting a partial reduction of As(V) to As(III) caused by nZVI oxidation.
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Affiliation(s)
- Elena Mele
- Dipartimento di Agraria, Sezione di Scienze e Tecnologie Ambientali e Alimentari, University of Sassari , Viale Italia 39, 07100 Sassari, Italy
| | - Erica Donner
- Centre for Environmental Risk Assessment and Remediation, University of South Australia , Building X, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia
- Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) , P.O. Box 486, Salisbury, South Australia 5106, Australia
| | - Albert L Juhasz
- Centre for Environmental Risk Assessment and Remediation, University of South Australia , Building X, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia
- Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) , P.O. Box 486, Salisbury, South Australia 5106, Australia
| | - Gianluca Brunetti
- Centre for Environmental Risk Assessment and Remediation, University of South Australia , Building X, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia
- Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) , P.O. Box 486, Salisbury, South Australia 5106, Australia
| | - Euan Smith
- Centre for Environmental Risk Assessment and Remediation, University of South Australia , Building X, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia
- Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) , P.O. Box 486, Salisbury, South Australia 5106, Australia
| | - Aaron R Betts
- Office of Research and Development, National Risk Management Research Laboratory, United States Environmental Protection Agency , 26 West Martin Luther King Drive, Cincinnati, Ohio 45268, United States
- Oak Ridge Institute for Science and Education , P.O. Box 117, Oak Ridge, Tennessee 37831, United States
| | - Paola Castaldi
- Dipartimento di Agraria, Sezione di Scienze e Tecnologie Ambientali e Alimentari, University of Sassari , Viale Italia 39, 07100 Sassari, Italy
| | - Salvatore Deiana
- Dipartimento di Agraria, Sezione di Scienze e Tecnologie Ambientali e Alimentari, University of Sassari , Viale Italia 39, 07100 Sassari, Italy
| | - Kirk G Scheckel
- National Risk Management Research Laboratory, United States Environmental Protection Agency , 5995 Centre Hill Avenue, Cincinnati, Ohio 45224, United States
| | - Enzo Lombi
- Centre for Environmental Risk Assessment and Remediation, University of South Australia , Building X, Mawson Lakes Campus, Adelaide, South Australia 5095, Australia
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Abstract
Biochars produced from meat and bonemeal (MBM) waste materials contain large amounts of calcium phosphate and are potentially useful sorbents for the remediation of metals. Because the reactivity of biochars depends strongly upon the conditions used in their production, the objective of this study was to evaluate the rates and mechanisms of Zn sorption onto a commercially supplied MBM biochar prior to its application in a field-scale revegetation project. Sorption experiments varying pH, time, and Zn concentration found that, above pH 6.1, Zn adsorbed to MBM biochar quickly (within 5 h) with a maximum adsorption capacity of 0.65 mmol Zn g(-1). Synchrotron-based Zn K-edge extended X-ray absorption fine structure spectroscopy was consistent with a tetrahedral Zn bound to phosphate groups in a monodentate inner-sphere surface complex for all conditions tested. With an acidification pretreatment and at more acidic pH, MBM biochar causes precipitation of a ZnPO4 phase. On the basis of these results, this MBM biochar has a high capacity to rapidly adsorb Zn in adsorption experiments and can be considered a promising sorbent for Zn remediation of contaminated soils.
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Affiliation(s)
- Aaron R Betts
- Oak Ridge Institute for Science and Education , U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, United States
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