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Wade AM, Peloquin DM, Matheson JM, Luxton TP. Dermal and oral exposure risks to heavy metals from 3D printing metal-fill thermoplastics. Sci Total Environ 2023; 903:166538. [PMID: 37625731 PMCID: PMC10653099 DOI: 10.1016/j.scitotenv.2023.166538] [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: 06/13/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 08/27/2023]
Abstract
Manufacturing advancements in polymer printing now allow for the addition of metal additives to thermoplastic feedstock up to 80-90 % by weight and subsequent printing on low-cost desktop 3D printers. Particles associated with metal additives are not chemically bound to the plastic polymer, meaning these particles can potentially migrate and become bioavailable. This study investigated the degree to which two human exposure pathways, oral (ingestion) and dermal (skin contact), are important exposure pathways for metals (copper, chromium, and tin) from metal-fill thermoplastics used in consumer fused filament fabrication (FFF). We found that dermal exposure to copper and bronze filaments presents the highest exposure risk due to chloride (Cl-) in synthetic sweat driving copper (Cu2+) release and dissolution. Chromium and tin were released as micron-sized particles < 24 μm in diameter with low bioaccessibility during simulated oral and dermal exposure scenarios, with potential to undergo dissolution in the gastrointestinal tract based on testing using synthetic stomach fluids. The rate of metal particle release increased by one to two orders of magnitude when thermoplastics were degraded under 1 year of simulated UV weathering. This calls into question the long-term suitability of biodegradable polymers such as PLA for use in metal-fill thermoplastics if they are designed not to be sintered. The greatest exposure risk appears to be from the raw filaments rather than the printed forms, with the former having higher metal release rates in water and synthetic body fluids for all but one filament type. For brittle feedstock that requires greater handling, as metal-fill thermoplastics can be, practices common in metal powder 3D printing such as wearing gloves and washing hands may adequately reduce metal exposure risks.
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Affiliation(s)
- Anna M Wade
- Oak Ridge Institute for Science and Education, 1299 Bethel Valley Road, Oak Ridge, TN 37830, USA; U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA.
| | - Derek M Peloquin
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA.
| | - Joanna M Matheson
- U.S. Consumer Product and Safety Commission, 5 Research Place, Rockville, MD 20850, USA.
| | - Todd P Luxton
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA.
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2
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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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3
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Zhang Q, Weber RJ, Luxton TP, Peloquin DM, Baumann EJ, Black MS. Metal compositions of particle emissions from material extrusion 3D printing: Emission sources and indoor exposure modeling. Sci Total Environ 2023; 860:160512. [PMID: 36442638 PMCID: PMC10259682 DOI: 10.1016/j.scitotenv.2022.160512] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/26/2022] [Accepted: 11/22/2022] [Indexed: 06/14/2023]
Abstract
Material extrusion 3D printing has been widely used in industrial, educational and residential environments, while its exposure health impacts have not been well understood. High levels of ultrafine particles are found being emitted from 3D printing and could pose a hazard when inhaled. However, metals that potentially transfer from filament additives to emitted particles could also add to the exposure hazard, which have not been well characterized for their emissions. This study analyzed metal (and metalloid) compositions of raw filaments and in the emitted particles during printing; studied filaments included pure polymer filaments with metal additives and composite filaments with and without metal powder. Our chamber study found that crustal metals tended to have higher partitioning factors from filaments to emitted particles; silicon was the most abundant element in emitted particles and had the highest yield per filament mass. However, bronze and stainless-steel powder added in composite filaments were less likely to transfer from filament to particle. For some cases, boron, arsenic, manganese, and lead were only detected in particles, which indicated external sources, such as the printers themselves. Heavy metals with health concerns were also detected in emitted particles, while their estimated exposure concentrations in indoor air were below air quality standards and occupational regulations. However, total particle exposure concentrations estimated for indoor environments could exceed ambient air fine particulate standards.
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Affiliation(s)
- Qian Zhang
- Chemical Insights Research Institute, Underwriters Laboratories Inc., Marietta, GA 30067, USA.
| | - Rodney J Weber
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Todd P Luxton
- U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Cincinnati, OH 45224, USA
| | - Derek M Peloquin
- U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Cincinnati, OH 45224, USA; Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, USA
| | - Eric J Baumann
- U.S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Cincinnati, OH 45224, USA
| | - Marilyn S Black
- Chemical Insights Research Institute, Underwriters Laboratories Inc., Marietta, GA 30067, USA
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4
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Eckley CS, Eagles-Smith C, Luxton TP, Hoffman J, Janssen S. Using mercury stable isotope fractionation to identify the contribution of historical mercury mining sources present in downstream water, sediment and fish. Front Environ Chem 2023; 4:1096199. [PMID: 37323923 PMCID: PMC10269370 DOI: 10.3389/fenvc.2023.1096199] [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: 06/17/2023]
Abstract
Ecosystems downstream of mercury (Hg) contaminated sites can be impacted by both localized releases as well as Hg deposited to the watershed from atmospheric transport. Identifying the source of Hg in water, sediment, and fish downstream of contaminated sites is important for determining the effectiveness of source-control remediation actions. This study uses measurements of Hg stable isotopes in soil, sediment, water, and fish to differentiate between Hg from an abandoned Hg mine from non-mine-related sources. The study site is located within the Willamette River watershed (Oregon, United States), which includes free-flowing river segments and a reservoir downstream of the mine. The concentrations of total-Hg (THg) in the reservoir fish were 4-fold higher than those further downstream (>90 km) from the mine site in free-flowing sections of the river. Mercury stable isotope fractionation analysis showed that the mine tailings (δ202Hg: -0.36‰ ± 0.03‰) had a distinctive isotopic composition compared to background soils (δ202Hg: -2.30‰ ± 0.25‰). Similar differences in isotopic composition were observed between stream water that flowed through the tailings (particulate bound δ202Hg: -0.58‰; dissolved: -0.91‰) versus a background stream (particle-bound δ202Hg: -2.36‰; dissolved: -2.09‰). Within the reservoir sediment, the Hg isotopic composition indicated that the proportion of the Hg related to mine-release increased with THg concentrations. However, in the fish samples the opposite trend was observed-the degree of mine-related Hg was lower in fish with the higher THg concentrations. While sediment concentrations clearly show the influence of the mine, the relationship in fish is more complicated due to differences in methylmercury (MeHg) formation and the foraging behavior of different fish species. The fish tissue δ13C and Δ199Hg values indicate that there is a higher influence of mine-sourced Hg in fish feeding in a more sediment-based food web and less so in planktonic and littoral-based food webs. Identifying the relative proportion of Hg from local contaminated site can help inform remediation decisions, especially when the relationship between total Hg concentrations and sources do not show similar covariation between abiotic and biotic media.
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Affiliation(s)
| | - Collin Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, OR, United States
| | - Todd P. Luxton
- US EPA ORD, Center for Environmental Solutions and Emergency Response, Cincinnati, OH, United States
| | - Joel Hoffman
- U.S. EPA Office of Research and Development, Center for Computational Toxicology and Exposure, Great Lakes Toxicology and Ecology Division, Duluth, MN, United States
| | - Sarah Janssen
- U.S. Geological Survey, Mercury Research Lab, Upper Midwest Water Science Center, Madison, WI, United States
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5
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Millard G, Eckley CS, Luxton TP, Krabbenhoft D, Goetz J, McKernan J, DeWild J. Evaluating the influence of seasonal stratification on mercury methylation rates in the water column and sediment in a contaminated section of a western U.S.A. reservoir. Environ Pollut 2023; 316:120485. [PMID: 36279994 PMCID: PMC10259237 DOI: 10.1016/j.envpol.2022.120485] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [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: 05/27/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 06/14/2023]
Abstract
Mercury methylation frequently occurs at the active oxic/anoxic boundary between the sediment bed and water column of lakes and reservoirs. Previous studies suggest that the predominant mercury methylation zone moves to the water column during periods of stratification and that high potential methylation rates (Km) in sediment require oxygenated overlying water. However, simultaneous measurements of methylmercury (MeHg) production in both the sediment and water column remain limited. Understanding the relative importance of sediment versus water column methylation and the impact of seasonal stratification on these processes has important implications for managing MeHg production. This study measured Km and potential demethylation rates (Kdm) using stable isotope tracers of unfiltered inorganic mercury and MeHg in sediments and water of the littoral and profundal zones of a shallow branch of the Nacimiento Reservoir in California's central coastal range. Field sampling was conducted once during winter (well-mixed/oxygenated conditions) and once during late summer (thermally stratified/anoxic conditions). The results showed very high ambient MeHg concentrations in hypolimnetic waters (up to 7.5 ng L-1; 79% MeHg/total Hg). During late summer, littoral sediments had higher Km (0.024 day-1) compared to profundal sediments (0.013 day-1). Anoxic water column Km were of similar magnitude to Km in the sediment (0.03 day-1). Following turnover, profundal sediment Km did not change significantly, but water column Km became insignificant. Summer and winter sediment Kdm were higher in profundal (2.35, 3.54 day-1, respectively) compared to the littoral sediments (0.52, 2.56 day-1, respectively). When modelled, Km in the water column could account for approximately 40% of the hypolimnetic MeHg. Our modelling results show that the remaining MeHg in the hypolimnion could originate from the profundal sediment. While further study is needed, these results suggest that addressing methylation in the water column and profundal sediment are of equal importance to any remediation strategy.
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Affiliation(s)
- Geoffrey Millard
- U.S.A. Environmental Protection Agency, Office of Research and Development, 26 W Martin Luther King Dr, Cincinnati, OH, 45220, USA.
| | - Chris S Eckley
- U.S.A. Environmental Protection Agency, Region 10, 1200 Sixth Avenue, Suite 155, Seattle WA, 98101, USA.
| | - Todd P Luxton
- U.S.A. Environmental Protection Agency, Office of Research and Development, 26 W Martin Luther King Dr, Cincinnati, OH, 45220, USA.
| | - David Krabbenhoft
- U.S.A. Geological Survey, Mercury Research Laboratory, 2280 Woodale Drive, Mounds View MN, 55112, USA.
| | - Jennifer Goetz
- U.S.A. Environmental Protection Agency, Office of Research and Development, 26 W Martin Luther King Dr, Cincinnati, OH, 45220, USA.
| | - John McKernan
- U.S.A. Environmental Protection Agency, Office of Research and Development, 26 W Martin Luther King Dr, Cincinnati, OH, 45220, USA.
| | - John DeWild
- U.S.A. Geological Survey, Mercury Research Laboratory, 2280 Woodale Drive, Mounds View MN, 55112, USA.
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6
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Hatch AC, Peloquin D, Kumbar AS, Luxton TP, Clar JG. Transformation of zinc oxide nanoparticles in synthetic lung fluids. J Nanopart Res 2022; 24:153. [PMID: 35873670 PMCID: PMC9288259 DOI: 10.1007/s11051-022-05527-y] [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] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/30/2022] [Indexed: 06/15/2023]
Abstract
UNLABELLED Surface coatings, including paints, stains, and sealants, have recently become a focus of "nano-enabled" consumer product engineering. Specifically, zinc oxide (ZnO) nanoparticles (NPs) have been introduced to surface coatings to increase UV resistance. As more "nano-enabled" products are made available for purchase, questions arise regarding their long-term environmental and human health effects. This study tracked the transformation of NP additives commonly added to consumer paints and stains using ZnO NPs as a model system. During product application and use, there is a risk of inhalation of aerosolized ZnO NPs. To investigate the potential chemical interactions and transformations that would occur after inhalation, ZnO NPs were incubated in two synthetic lung fluids (SLFs). Initial studies utilized ZnO NPs dispersed in Milli-Q water (control), or a commercially available deck stain. Additionally, two commercially available products advertising the inclusion of ZnO NP additives were evaluated. Subsamples were taken throughout incubation and analyzed via atomic absorption spectroscopy to determine both the total (including particulate) zinc concentration and dissolved (non-particulate) zinc concentration. Results indicate that the vast majority of ZnO transformation takes place within the first 24 h of incubation and is primarily driven by SLF pH and composition complexity. Significant dissolution of ZnO NPs was observed when incubated in Gamble's solution (between 25 and 68% depending on the matrix. Additionally, all ZnO solutions saw near immediate dissolution (~ 98-100%) within 3 h of incubation in artificial lysosomal fluid. Results illustrate potential for NPs in consumer products to undergo significant transformation during use and exposure over short time periods. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1007/s11051-022-05527-y.
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Affiliation(s)
- Avery C Hatch
- Department of Chemistry, Elon University, Elon, NC 27244 USA
| | - Derek Peloquin
- Oak Ridge Institute for Science and Education (ORISE) Postdoctoral Research Associate, Oak Ridge, USA
| | - Amar S Kumbar
- Analytical and Nanofabrication Laboratory, University of North Carolina, Chapel Hill, NC 27599 USA
| | - Todd P Luxton
- Center for Environmental Solutions and Environmental Response, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224 USA
| | - Justin G Clar
- Department of Chemistry, Elon University, Elon, NC 27244 USA
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7
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Plunkett SA, Eckley CS, Luxton TP, Johnson MG. The effects of biochar and redox conditions on soil Pb bioaccessibility to people and waterfowl. Chemosphere 2022; 294:133675. [PMID: 35066080 PMCID: PMC9942605 DOI: 10.1016/j.chemosphere.2022.133675] [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: 09/24/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 05/03/2023]
Abstract
Biochar can reduce lead (Pb) bioavailability to plants in metal-contaminated soil, but the ability of biochar to reduce the bioavailability of soil Pb to people and wildlife remains unknown. In this study, 17 biochars were evaluated as in situ amendments for three soils with distinct sources of Pb contamination (smelter emissions, ceramics waste, mining waste), hydrology (upland, well-drained soil vs submerged wetland soil), and biological receptors (human vs waterfowl). Biochars were made from blends of 30% manure (poultry litter or dairy manure) and 70% lignocellulosic material (wheat straw or grand fir shavings) and pyrolyzed at 300, 500, 700, and 900 °C. Soils were amended with 2% biochar (w/w) and incubated for 6 months. A suite of standard (e.g., EPA Method 1340) and experimental soil Pb bioaccessibility assays were used to assess the impact of the treatments. The results showed that biochar amendments to upland soils resulted in modest reductions in gastrointestinal Pb bioaccessibility (maximum reduction from 78 to 68% bioaccessibility as a percent of total, EPA Method 1340 at pH 2.5). In the wetland soil, sample redox status had a greater impact on Pb bioaccessibility than any amendment. Low-solubility Pb sulfides in this soil oxidized over the course of the study and no treatment was able to offset the increase in Pb bioaccessibility caused by this oxidation. The impact of redox status on Pb bioaccessibility was only evident when soil bioaccessibility assays were adapted to preserve sample redox status. This result highlights the importance of maintaining in situ redox conditions when processing/analyzing samples from low-oxygen environments and that soil remediation efforts should consider the role of redox conditions on Pb bioaccessibility.
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Affiliation(s)
- Shannon A Plunkett
- Oak Ridge Institute for Science and Education (ORISE) Fellow, c/o U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, 200 SW 35th St, Corvallis, OR, 97333, USA; Duke University, Department of Civil and Environmental Engineering, 121 Hudson Hall, 100 Science Drive, Durham, NC, 27710, USA.
| | - Chris S Eckley
- U.S. Environmental Protection Agency, Region 10, 14 Park Place Building, 1200 6th Ave, Seattle, WA, 98101, USA.
| | - Todd P Luxton
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Solutions and Emergency Response, Land Remediation and Technology Division. 5995 Center Hill Ave, Cincinnati, OH, 45224, USA.
| | - Mark G Johnson
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, 200 SW 35th St, Corvallis, OR, 97333, USA.
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8
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Wang D, Saleh NB, Byro A, Zepp R, Sahle-Demessie E, Luxton TP, Ho KT, Burgess RM, Flury M, White JC, Su C. Nano-enabled pesticides for sustainable agriculture and global food security. Nat Nanotechnol 2022; 17:347-360. [PMID: 35332293 PMCID: PMC9774002 DOI: 10.1038/s41565-022-01082-8] [Citation(s) in RCA: 112] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 01/27/2022] [Indexed: 05/02/2023]
Abstract
Achieving sustainable agricultural productivity and global food security are two of the biggest challenges of the new millennium. Addressing these challenges requires innovative technologies that can uplift global food production, while minimizing collateral environmental damage and preserving the resilience of agroecosystems against a rapidly changing climate. Nanomaterials with the ability to encapsulate and deliver pesticidal active ingredients (AIs) in a responsive (for example, controlled, targeted and synchronized) manner offer new opportunities to increase pesticidal efficacy and efficiency when compared with conventional pesticides. Here, we provide a comprehensive analysis of the key properties of nanopesticides in controlling agricultural pests for crop enhancement compared with their non-nanoscale analogues. Our analysis shows that when compared with non-nanoscale pesticides, the overall efficacy of nanopesticides against target organisms is 31.5% higher, including an 18.9% increased efficacy in field trials. Notably, the toxicity of nanopesticides toward non-target organisms is 43.1% lower, highlighting a decrease in collateral damage to the environment. The premature loss of AIs prior to reaching target organisms is reduced by 41.4%, paired with a 22.1% lower leaching potential of AIs in soils. Nanopesticides also render other benefits, including enhanced foliar adhesion, improved crop yield and quality, and a responsive nanoscale delivery platform of AIs to mitigate various pressing biotic and abiotic stresses (for example, heat, drought and salinity). Nonetheless, the uncertainties associated with the adverse effects of some nanopesticides are not well-understood, requiring further investigations. Overall, our findings show that nanopesticides are potentially more efficient, sustainable and resilient with lower adverse environmental impacts than their conventional analogues. These benefits, if harnessed appropriately, can promote higher crop yields and thus contribute towards sustainable agriculture and global food security.
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Affiliation(s)
- Dengjun Wang
- Oak Ridge Institute for Science and Education, US Environmental Protection Agency, Ada, OK, USA.
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL, USA.
| | - Navid B Saleh
- Department of Civil, Architectural and Environmental Engineering, University of Texas, Austin, TX, USA
| | - Andrew Byro
- Antimicrobials Division, Office of Pesticide Programs, US Environmental Protection Agency, Arlington, VA, USA
| | - Richard Zepp
- Center for Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Athens, GA, USA
| | - Endalkachew Sahle-Demessie
- Center for Environmental Solutions and Emergency Response, Office of Research and Development, US Environmental Protection Agency, Cincinnati, OH, USA
| | - Todd P Luxton
- Center for Environmental Solutions and Emergency Response, Office of Research and Development, US Environmental Protection Agency, Cincinnati, OH, USA
| | - Kay T Ho
- Center for Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Narragansett, RI, USA
| | - Robert M Burgess
- Center for Environmental Measurement and Modeling, Office of Research and Development, US Environmental Protection Agency, Narragansett, RI, USA
| | - Markus Flury
- Department of Crop and Soil Sciences, Washington State University, Puyallup and Pullman, WA, USA
| | - Jason C White
- Connecticut Agricultural Experiment Station, New Haven, CT, USA
| | - Chunming Su
- Center for Environmental Solutions and Emergency Response, Office of Research and Development, US Environmental Protection Agency, Ada, OK, USA.
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9
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Johnson MG, Luxton TP, Rygiewicz PT, Reichman JR, Bollman MA, King GA, Storm MJ, Nash MS, Andersen CP. Transformation and release of micronized Cu used as a wood preservative in treated wood in wetland soil. Environ Pollut 2021; 287:117189. [PMID: 34023660 PMCID: PMC9299944 DOI: 10.1016/j.envpol.2021.117189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [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: 12/03/2020] [Revised: 04/08/2021] [Accepted: 04/16/2021] [Indexed: 06/12/2023]
Abstract
Micronized Cu (μ-Cu) is used as a wood preservative, replacing toxic chromated copper arsenate (CCA). Micronized Cu is malachite [Cu2CO3(OH)2] that has been milled to micron/submicron particles, with many particle diameters less than 100 nm, mixed with biocides and then used to treat wood. In addition to concerns about the fate of the Cu from μ-Cu, there is interest in the fate of the nano-Cu (n-Cu) constituents. We examined movement of Cu from μ-Cu-treated wood after placing treated-wood stakes into model wetland ecosystems. Release of Cu into surface and subsurface water was monitored. Surface water Cu reached maximum levels 3 days after stake installation and remained elevated if the systems remained inundated. Subsurface water Cu levels were 10% of surface water levels at day 3 and increased gradually thereafter. Sequential filtering indicated that a large portion of the Cu in solution was associating with soluble organics, but there was no evidence for n-Cu in solution. After 4 months, Cu in thin-sections of treated wood and adjacent soil were characterized with micro X-ray absorption fine structure spectroscopy (μ-XAFS). Localization and speciation of Cu in the wood and adjacent soil using μ-XAFS clearly indicated that Cu concentrations decreased over time in the treated wood and increased in the adjacent soil. However, n-Cu from the treated wood was not found in the adjacent soil or plant roots. The results of this study indicate that Cu in the μ-Cu-treated wood dissolves and migrates into adjacent soil and waters primarily in ionic form (i.e., Cu2+) and not as nano-sized Cu particles. A reduced form of Cu (Cu2S) was identified in deep soil proximal to the treated wood, indicating strong reducing conditions. The formation of the insoluble Cu2S effectively removes some portion of dissolved Cu from solution, reducing movement of Cu2+ to the water column and diminishing exposure.
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Affiliation(s)
- M G Johnson
- EPA, ORD, Center for Public Health and Environmental Assessment, Corvallis, OR, USA.
| | - T P Luxton
- EPA, ORD, Center for Environmental Solutions and Emergency Response, Cincinnati, OH, USA
| | - P T Rygiewicz
- EPA, ORD, Center for Public Health and Environmental Assessment, Corvallis, OR, USA
| | - J R Reichman
- EPA, ORD, Center for Public Health and Environmental Assessment, Corvallis, OR, USA
| | - M A Bollman
- EPA, ORD, Center for Public Health and Environmental Assessment, Corvallis, OR, USA
| | | | | | - M S Nash
- EPA, ORD, Center for Public Health and Environmental Assessment, Corvallis, OR, USA
| | - C P Andersen
- EPA, ORD, Center for Public Health and Environmental Assessment, Corvallis, OR, USA
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10
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Thornton SB, Luxton TP, Clar JG. Variation in zinc release from surface coatings as a function of methodology. Sci Total Environ 2021; 788:147907. [PMID: 34134384 PMCID: PMC9614699 DOI: 10.1016/j.scitotenv.2021.147907] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/23/2021] [Accepted: 05/16/2021] [Indexed: 06/12/2023]
Abstract
Over the last decade the growth of "nano-enabled" products have exploded in both industrial and direct to consumer applications. One area of interest is surface coatings, including paints, stains and sealants. Large scale applications of the products raise questions about both short- and long-term effects to both human and environmental health. Release of nanoparticles (NPs) from surfaces as a function of dermal contact is recognized as a potential human exposure route. Several standardized methods to quantify nanomaterial release have been previously used. In the current study, two standardized method were used to quantify the total mass of NPs released during sampling. ZnO (NPs) were used as a case study as they are commonly added to surface coatings to increase UV resistance. Particles were dispersed in Milli-Q water or a deck stain and applied to sanded plywood surfaces. Total release of Zn due to simulated dermal contact was evaluated using the Consumer Product Safety Commission (CPSC) and National Institute for Occupational Safety and Health (NIOSH) wipe methods. Additionally, three different sampling materials were tested. The total quantity of Zn released between the two methods was dependent upon the material used and how the ZnO was applied to the surface. Critically, less than 3% of the ZnO NPs applied to test surfaces was removed using either method. The results of this study demonstrate how different testing methodologies may result in varying estimates of human and environmental risk from NPs in surface coatings.
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Affiliation(s)
| | - Todd P Luxton
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Research and Emergency Response, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA
| | - Justin G Clar
- Elon University, Department of Chemistry, Elon, NC 27244, USA.
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11
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Eckley CS, Luxton TP, Knightes CD, Shah V. Methylmercury Production and Degradation under Light and Dark Conditions in the Water Column of the Hells Canyon Reservoirs, USA. Environ Toxicol Chem 2021; 40:1829-1839. [PMID: 33729607 PMCID: PMC8745031 DOI: 10.1002/etc.5041] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [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: 01/23/2021] [Revised: 02/28/2021] [Accepted: 03/09/2021] [Indexed: 05/28/2023]
Abstract
Methylmercury (MeHg) is a highly toxic form of mercury that can bioaccumulate in fish tissue. Methylmercury is produced by anaerobic bacteria, many of which are also capable of MeHg degradation. In addition, demethylation in surface waters can occur via abiotic sunlight-mediated processes. The goal of the present study was to understand the relative importance of microbial Hg methylation/demethylation and abiotic photodemethylation that govern the mass of MeHg within an aquatic system. The study location was the Hells Canyon complex of 3 reservoirs on the Idaho-Oregon border, USA, that has fish consumption advisories as a result of elevated MeHg concentrations. Our study utilized stable isotope addition experiments to trace MeHg formation and degradation within the water column of the reservoirs to understand the relative importance of these processes on the mass of MeHg using the Water Quality Analysis Simulation Program. The results showed that rates of MeHg production and degradation within the water column were relatively low (<0.07 d-1 ) but sufficient to account for most of the MeHg observed with the system. Most MeHg production within the water column appeared to occur in the spring when much of the water column was in the processes of becoming anoxic. In the surface waters, rates of photodemethylation were relatively large (up to -0.25 d-1 ) but quickly decreased at depths >0.5 m below the surface. These results can be used to identify the relative importance of MeHg processes that can help guide reservoir management decisions. Environ Toxicol Chem 2021;40:1829-1839. © 2021 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Chris S. Eckley
- US Environmental Protection Agency, Region-10, Seattle, Washington
| | - Todd P. Luxton
- Office of Research and Development, US Environmental Protection Agency, Cincinnati, Ohio
| | - Christopher D. Knightes
- Office of Research and Development, US Environmental Protection Agency, Narragansett, Rhode Island
| | - Vishal Shah
- College of the Sciences and Mathematics, West Chester University, West Chester, Pennsylvania, USA
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12
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Eckley CS, Luxton TP, Stanfield B, Baldwin A, Holloway J, McKernan J, Johnson MG. Effect of organic matter concentration and characteristics on mercury mobilization and methylmercury production at an abandoned mine site. Environ Pollut 2021; 271:116369. [PMID: 33401216 PMCID: PMC7903515 DOI: 10.1016/j.envpol.2020.116369] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [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: 07/03/2020] [Revised: 12/16/2020] [Accepted: 12/20/2020] [Indexed: 05/05/2023]
Abstract
Thousands of abandoned mines throughout the western region of North America contain elevated total-mercury (THg) concentrations. Mercury is mobilized from these sites primarily due to erosion of particulate-bound Hg (THg-P). Organic matter-based soil amendments can promote vegetation growth on mine tailings, reducing erosion and subsequent loading of THg-P into downstream waterbodies. However, the introduction of a labile carbon source may stimulate microbial activity that can produce methylmercury (MeHg)-the more toxic and bioaccumulative form of Hg. Our objectives were to investigate how additions of different organic matter substrates impact Hg mobilization and methylation using a combination of field observations and controlled experiments. Field measurements of water, sediment, and porewater were collected downstream of the site and multi-year monitoring (and load calculations) were conducted at a downstream gaging station. MeHg production was assessed using stable isotope methylation assays and mesocosm experiments that were conducted using different types of organic carbon soil amendments mixed with materials from the mine site. The results showed that >80% of the THg mobilized from the mine was bound to particles and that >90% of the annual Hg loading occurred during the period of elevated discharge during spring snowmelt. Methylation rates varied between different types of soil amendments and were correlated with the components of excitation emission matrices (EEMs) associated with humic acid fractions of organic matter. The mesocosm experiments showed that under anoxic conditions carbon amendments to tailings could significantly increase porewater MeHg concentrations (up to 13 ± 3 ng/L). In addition, the carbon amendments significantly increased THg partitioning into porewater. Overall, these results indicate that soil amendment applications to reduce surface erosion at abandoned mine sites could be effective at reducing particulate Hg mobilization to downstream waterbodies; however, some types of carbon amendments can significantly increase Hg methylation as well as increase the mobilization of dissolved THg from the site.
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Affiliation(s)
- Chris S Eckley
- U.S. Environmental Protection Agency, Region-10, Seattle, WA, USA.
| | - Todd P Luxton
- U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA
| | - Brooks Stanfield
- U.S. Environmental Protection Agency, Region-10, Seattle, WA, USA
| | - Austin Baldwin
- U.S. Geological Survey, Idaho Water Science Center, Boise, ID, USA
| | - JoAnn Holloway
- U.S. Geological Survey, Geology, Geophysics, and Geochemistry Science Center, Denver, CO, USA
| | - John McKernan
- U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA
| | - Mark G Johnson
- U.S. Environmental Protection Agency, Office of Research and Development, Center for Public Health and Environmental Assessment, Pacific Ecological Systems Division, Corvallis, OR, USA
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13
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Thornton SB, Boggins SJ, Peloquin DM, Luxton TP, Clar JG. Release and transformation of nanoparticle additives from surface coatings on pristine & weathered pressure treated lumber. Sci Total Environ 2020; 737:139451. [PMID: 32512308 PMCID: PMC8025203 DOI: 10.1016/j.scitotenv.2020.139451] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 04/12/2020] [Accepted: 05/13/2020] [Indexed: 04/14/2023]
Abstract
As the market for "nano-enabled" products (NEPs) continues to expand in commercial and industrial applications, there is a critical need to understand conditions that promote release of nanomaterials and their degradation products from NEPs. Moreover, these studies must aim to quantify both the abundance and form (aggregates, ions, hybrids, etc.) of material released from NEPs to produce reasonable estimates of human and environmental exposure. In this work ZnO nanoparticles (NPs), a common additive in NEP surface coatings, were dispersed in Milli-Q water and a commercially available wood stain before application to pristine and weathered (outdoor 1 year) micronized copper azole pressure treated lumber (MCA). Coated lumber surfaces were sampled consecutively eight times using a method developed by the Consumer Product Safety Commission (CPSC) to track potential human exposure to ZnO NPs and byproducts through simulated dermal contact. Surprisingly, the highest total release of Zn was observed from aged lumber coated with ZnO NPs dispersed in wood stain, releasing 233 ± 26 mg Zn/m2 over the course of all sampling events. Alternatively, separate leaching experiments using a synthetic precipitation solution to simulate environmental release found aged lumber released significantly less Zn than pristine lumber when using the same coating formulation. Zinc speciation analysis also demonstrates that transformation of crystalline ZnO to Zn-organic complexes shortly after application to aged lumber. Regardless of experimental treatment, the majority of applied zinc (>75%) remains on the MCA surface. Finally, this work highlights how the nature of the screening technique (dermal contact vs. leaching) may result in different interpretations of exposure and risk.
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Affiliation(s)
| | - Sarah J Boggins
- Elon University, Department of Chemistry, Elon, NC 27244, USA
| | - Derek M Peloquin
- Oak Ridge Institute for Science and Education (ORISE) Postdoctoral Research Associate, USA
| | - Todd P Luxton
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA
| | - Justin G Clar
- Elon University, Department of Chemistry, Elon, NC 27244, USA.
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Lentz DL, Hamilton TL, Dunning NP, Scarborough VL, Luxton TP, Vonderheide A, Tepe EJ, Perfetta CJ, Brunemann J, Grazioso L, Valdez F, Tankersley KB, Weiss AA. Molecular genetic and geochemical assays reveal severe contamination of drinking water reservoirs at the ancient Maya city of Tikal. Sci Rep 2020; 10:10316. [PMID: 32587274 PMCID: PMC7316703 DOI: 10.1038/s41598-020-67044-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 06/02/2020] [Indexed: 11/09/2022] Open
Abstract
Understanding civilizations of the past and how they emerge and eventually falter is a primary research focus of archaeological investigations because these provocative data sets offer critical insights into long-term human behavior patterns, especially in regard to land use practices and sustainable environmental interactions. The ancient Maya serve as an intriguing example of this research focus, yet the details of their spectacular emergence in a tropical forest environment followed by their eventual demise have remained enigmatic. Tikal, one of the foremost of the ancient Maya cities, plays a central role in this discussion because of its sharp population decline followed by abandonment during the late 9th century CE. Our results, based on geochemical and molecular genetic assays on sediments from four of the main reservoirs, reveal that two of the largest reservoirs at Tikal, essential for the survival of the city during the dry seasons, were contaminated with high levels of mercury, phosphate and cyanobacteria known to produce deadly toxins. Our observations demonstrate severe pollution problems at a time when episodes of climatic aridity were prevalent. This combination of catastrophic events clearly threatened the sustainability of the city and likely contributed to its abandonment.
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Affiliation(s)
- David L Lentz
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, 45221, USA.
| | - Trinity L Hamilton
- Department of Plant and Microbial Biology and the BioTechnology Institute, University of Minnesota, St. Paul, MN, 55108, USA
| | - Nicholas P Dunning
- Department of Geography, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Vernon L Scarborough
- Department of Anthropology, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Todd P Luxton
- National Risk Management Research Laboratory, US Environmental Protection Agency, Cincinnati, OH, 45224, USA
| | - Anne Vonderheide
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Eric J Tepe
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Cory J Perfetta
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - James Brunemann
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Liwy Grazioso
- Museo Miraflores, 7 Calle 21-55, Guatemala City, Guatemala
| | - Fred Valdez
- Department of Anthropology, University of Texas, Austin, TX, 78212, USA
| | - Kenneth B Tankersley
- Department of Anthropology, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Alison A Weiss
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, OH, 45267, USA
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15
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Peloquin DM, Baumann EJ, Luxton TP. Multi-method assessment of PVP-coated silver nanoparticles and artificial sweat mixtures. Chemosphere 2020; 249:126173. [PMID: 32065993 PMCID: PMC7449241 DOI: 10.1016/j.chemosphere.2020.126173] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [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: 11/04/2019] [Revised: 02/04/2020] [Accepted: 02/09/2020] [Indexed: 05/19/2023]
Abstract
Research presented here utilizes silver nanoparticles (AgNPs) as a case study for how the immediate local environment alters the physical and chemical properties of nanomaterials. Dermal exposure is a primary route for exposure to many of the consumer products containing AgNPs. Interactions between AgNPs and human sweat/perspiration are critical for understanding how changes in Ag speciation will impact exposure. Previous studies have examined silver release from AgNP-containing products after exposure to artificial sweat (AS), however there is no basic assessment of how mixtures of AgNPs and AS alter the physical and chemical properties of AgNPs. The current research evaluated changes in size, aggregation, chemical composition, and silver speciation of four different sizes of AgNPs exposed to four different formulations of AS. The AS formulations were from standardized methods with different chemical compositions, ionic strengths, and pH. Samples were collected at four-time intervals for analysis using dynamic light scattering , UV-Vis spectroscopy, and single-particle inductively coupled plasma-mass spectrometry . Each mixture was also prepared for speciation analysis using X-ray absorption spectroscopy and scanning electron microscopy coupled to energy-dispersive X-ray analysis. The equivalent diameter measurements from the three techniques followed the order of DLS > UV-Vis > spICP-MS. Speciation analyses indicate significant changes for the smaller NPs, while the largest (100 nm) NPs had less measurable differences. This study shows the need to fully understand what specific information an analytical technique might provide and to use those techniques properly in tandem to give the fullest answer to a given research question.
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Affiliation(s)
- Derek M Peloquin
- Oak Ridge Institute for Science and Education, 1299 Bethel Valley Rd, Oak Ridge, TN, 37830, USA; U.S. Environmental Protection Agency, Office of Research and Development, 26 West Martin Luther King Dr, Cincinnati, OH, 45268, USA.
| | - Eric J Baumann
- Oak Ridge Institute for Science and Education, 1299 Bethel Valley Rd, Oak Ridge, TN, 37830, USA; Pegasus Technical Services, Inc., 46 East Hollister Street, Cincinnati, OH, 45219, USA.
| | - Todd P Luxton
- U.S. Environmental Protection Agency, Office of Research and Development, 26 West Martin Luther King Dr, Cincinnati, OH, 45268, USA.
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16
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Eckley CS, Gilmour CC, Janssen S, Luxton TP, Randall PM, Whalin L, Austin C. The assessment and remediation of mercury contaminated sites: A review of current approaches. Sci Total Environ 2020; 707:136031. [PMID: 31869604 PMCID: PMC6980986 DOI: 10.1016/j.scitotenv.2019.136031] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/07/2019] [Accepted: 12/07/2019] [Indexed: 04/13/2023]
Abstract
Remediation of mercury (Hg) contaminated sites has long relied on traditional approaches, such as removal and containment/capping. Here we review contemporary practices in the assessment and remediation of industrial-scale Hg contaminated sites and discuss recent advances. Significant improvements have been made in site assessment, including the use of XRF to rapidly identify the spatial extent of contamination, Hg stable isotope fractionation to identify sources and transformation processes, and solid-phase characterization (XAFS) to evaluate Hg forms. The understanding of Hg bioavailability for methylation has been improved by methods such as sequential chemical extractions and porewater measurements, including the use of diffuse gradient in thin-film (DGT) samplers. These approaches have shown varying success in identifying bioavailable Hg fractions and further study and field applications are needed. The downstream accumulation of methylmercury (MeHg) in biota is a concern at many contaminated sites. Identifying the variables limiting/controlling MeHg production-such as bioavailable inorganic Hg, organic carbon, and/or terminal electron acceptors (e.g. sulfate, iron) is critical. Mercury can be released from contaminated sites to the air and water, both of which are influenced by meteorological and hydrological conditions. Mercury mobilized from contaminated sites is predominantly bound to particles, highly correlated with total sediment solids (TSS), and elevated during stormflow. Remediation techniques to address Hg contamination can include the removal or containment of Hg contaminated materials, the application of amendments to reduce mobility and bioavailability, landscape/waterbody manipulations to reduce MeHg production, and food web manipulations through stocking or extirpation to reduce MeHg accumulated in desired species. These approaches often rely on knowledge of the Hg forms/speciation at the site, and utilize physical, chemical, thermal and biological methods to achieve remediation goals. Overall, the complexity of Hg cycling allows many different opportunities to reduce/mitigate impacts, which creates flexibility in determining suitable and logistically feasible remedies.
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Affiliation(s)
- Chris S Eckley
- U.S. Environmental Protection Agency, Region-10, 1200 6th Ave, Seattle, WA 98101, USA.
| | - Cynthia C Gilmour
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd., Edgewater, MD 21037-0028, USA.
| | - Sarah Janssen
- USGS Upper Midwest Water Science Center, 8505 Research Way, Middleton, WI 53562, USA.
| | - Todd P Luxton
- US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Paul M Randall
- US Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA.
| | - Lindsay Whalin
- San Francisco Bay Water Board, 1515 Clay St., Ste. 1400, Oakland, CA 94612, USA.
| | - Carrie Austin
- San Francisco Bay Water Board, 1515 Clay St., Ste. 1400, Oakland, CA 94612, USA.
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17
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Clar JG, Platten WE, Baumann E, Remsen A, Harmon S, Rodgers K, Thomas T, Matheson J, Luxton TP. Transformation and release of nanoparticle additives & byproducts from commercially available surface coatings on pressure treated lumber via dermal contact. Sci Total Environ 2019; 694:133669. [PMID: 31382174 PMCID: PMC7440215 DOI: 10.1016/j.scitotenv.2019.133669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [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: 06/04/2019] [Revised: 07/23/2019] [Accepted: 07/29/2019] [Indexed: 06/10/2023]
Abstract
Production and marketing of "nano-enabled" products for consumer purchase has continued to expand. However, many questions remain about the potential release and transformation of these nanoparticle (NP) additives from products throughout their lifecycle. In this work, two surface coating products advertised as containing ZnO NPs as active ingredients, were applied to micronized copper azol (MCA) and aqueous copper azol (ACA) pressure treated lumber. Coated lumber was weathered outdoors for a period of six months and the surface was sampled using a method developed by the Consumer Product Safety Commission (CPSC) to track potential human exposure to ZnO NPs and byproducts through simulated dermal contact. Using this method, the total amount of zinc extracted during a single sampling event was <1 mg/m2 and no evidence of free ZnO NPs was found. Approximately 0.5% of applied zinc was removed via simulated dermal contact over 6-months, with increased weathering periods resulting in increased zinc release. XAFS analysis found that only 27% of the zinc in the as received coating could be described as crystalline ZnO and highlights the transformation of these mineral phases to organically bound zinc complexes during the six-month weathering period. Additionally, SEM images collected after sampling found no evidence of free NP ZnO release during simulated dermal contact. Both simulated dermal contact experiments, and separate leaching studies demonstrate the application of surface coating solutions to either MCA and ACA lumber will reduce the release of copper from the pressure treated lumber. This work provides clear evidence of the transformation of NP additives in consumer products during their use stage.
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Affiliation(s)
- Justin G Clar
- Elon University, Department of Chemistry, Elon, NC 27244, USA
| | | | - Eric Baumann
- Pegasus Technical Services Inc, Cincinnati, OH, USA
| | | | - Steve Harmon
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA
| | - Kim Rodgers
- National Health Effects and Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Treye Thomas
- U.S. Consumer Product Safety Commission, Office of Hazard Identification and Reduction, 4330 East West Highway, Bethesda, MD 20814, USA
| | - Joanna Matheson
- U.S. Consumer Product Safety Commission, Office of Hazard Identification and Reduction, 4330 East West Highway, Bethesda, MD 20814, USA
| | - Todd P Luxton
- Elon University, Department of Chemistry, Elon, NC 27244, USA.
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18
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Clar JG, Platten WE, Baumann E, Remsen A, Harmon SM, Rodgers K, Thomas TA, Matheson J, Luxton TP. Release and transformation of ZnO nanoparticles used in outdoor surface coatings for UV protection. Sci Total Environ 2019; 670:78-86. [PMID: 30903905 PMCID: PMC6770995 DOI: 10.1016/j.scitotenv.2019.03.189] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/11/2019] [Accepted: 03/13/2019] [Indexed: 05/31/2023]
Abstract
A major area of growth for "nano-enabled" products has been the addition of nanoparticles (NPs) to surface coatings including paints, stains and sealants. Zinc oxide (ZnO) NPs, long used in sunscreens and sunblocks, have found growing use in surface coating formulations to increase their UV resistance, especially on outdoor products. In this work, ZnO NPs, marketed as an additive to paints and stains, were dispersed in Milli-Q water and a commercial deck stain. Resulting solutions were applied to either Micronized-Copper Azole (MCA) pressure treated lumber or a commercially available composite decking. A portion of coated surfaces were placed outdoors to undergo environmental weathering, while the remaining samples were stored indoors to function as experimental controls. Weathered and control treatments were subsequently sampled periodically for 6 months using a simulated dermal contact method developed by the Consumer Product Safety Commission (CPSC). The release of ZnO NPs, and their associated degradation products, was determined through sequential filtration, atomic spectroscopy, X-Ray Absorption Fine Structure Spectroscopy, and electron microscopy. Across all treatments, the percentage of applied zinc released through simulated dermal contact did not exceed 4%, although transformation and release of zinc was highly dependent on dispersion medium. For MCA samples weathered outdoors, water-based applications released significantly more zinc than stain-based, 180 ± 28, and 65 ± 9 mg/m2 respectively. Moreover, results indicate that the number of contact events drives material release.
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Affiliation(s)
- Justin G Clar
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA; Oak Ridge Institute for Science and Education (ORISE) Postdoctoral Research Associate, USA.
| | | | - Eric Baumann
- Pegasus Technical Services Inc., Cincinnati, OH, USA
| | - Andrew Remsen
- Pegasus Technical Services Inc., Cincinnati, OH, USA
| | - Steve M Harmon
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA
| | - Kim Rodgers
- National Health Effects and Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Treye A Thomas
- U.S. Consumer Product Safety Commission, Office of Hazard Identification and Reduction, 4330 EastWest Highway, Bethesda, MD 20814, USA
| | - Joanna Matheson
- U.S. Consumer Product Safety Commission, Office of Hazard Identification and Reduction, 4330 EastWest Highway, Bethesda, MD 20814, USA
| | - Todd P Luxton
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA
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Parks AN, Cantwell MG, Katz DR, Cashman MA, Luxton TP, Clar JG, Perron MM, Portis L, Ho KT, Burgess RM. Assessing the release of copper from nanocopper-treated and conventional copper-treated lumber into marine waters II: Forms and bioavailability. Environ Toxicol Chem 2018; 37:1969-1979. [PMID: 29575127 PMCID: PMC6038930 DOI: 10.1002/etc.4140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [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: 12/07/2017] [Revised: 01/06/2018] [Accepted: 03/22/2018] [Indexed: 05/18/2023]
Abstract
One application of nanocopper is as a wood-preserving pesticide in pressure-treated lumber. Recent research has shown that pressure-treated lumber amended with micronized copper azole (MCA), which contains nanosized copper, releases copper under estuarine and marine conditions. The form of copper released (i.e., ionic, nanocopper [1-100 nm in size]) is not fully understood but will affect the bioavailability and toxicity of the metal. In the present study, multiple lines of evidence, including size fractionation, ion-selective electrode electrochemistry, comparative toxicity, and copper speciation were used to determine the form of copper released from lumber blocks and sawdust. The results of all lines of evidence supported the hypothesis that ionic copper was released from MCA lumber and sawdust, with little evidence that nanocopper was released. For example, copper concentrations in size fractionations of lumber block aqueous leachates including unfiltered, 0.1 μm, and 3 kDa were not significantly different, suggesting that the form of copper released was in the size range operationally defined as dissolved. These results correlated with the ion-selective electrode data which detects only ionic copper. In addition, comparative toxicity testing resulted in a narrow range of median lethal concentrations (221-257 μg/L) for MCA lumber blocks and CuSO4 . We conclude that ionic copper was released from the nanocopper pressure-treated lumber under estuarine and marine conditions. Environ Toxicol Chem 2018;37:1969-1979. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.
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Affiliation(s)
- Ashley N Parks
- National Research Council c/o U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
| | - Mark G Cantwell
- U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
| | - David R Katz
- U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
| | - Michaela A Cashman
- University of Rhode Island, Department of Geosciences, Kingston, RI, USA
| | - Todd P Luxton
- U.S. EPA, ORD/NRMRL, Land and Materials Management Division, Cincinnati, OH, USA
| | - Justin G Clar
- Oak Ridge Institute for Science and Education c/o U.S. EPA, ORD/NRMRL/LMMD, Cincinnati, OH, USA
| | - Monique M Perron
- US EPA, OCSPP, Office of Pesticides Programs, Washington, DC, USA
| | - Lisa Portis
- Lifespan Ambulatory Care Center, East Greenwich, RI USA
| | - Kay T Ho
- U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
| | - Robert M Burgess
- U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
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Parks AN, Cantwell MG, Katz DR, Cashman MA, Luxton TP, Ho KT, Burgess RM. Assessing the release of copper from nanocopper-treated and conventional copper-treated lumber into marine waters I: Concentrations and rates. Environ Toxicol Chem 2018; 37:1956-1968. [PMID: 29575152 PMCID: PMC6040830 DOI: 10.1002/etc.4141] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [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: 09/27/2017] [Revised: 12/08/2017] [Accepted: 03/13/2018] [Indexed: 05/18/2023]
Abstract
Little is known about the release of metal engineered nanomaterials (ENMs) from consumer goods, including lumber treated with micronized copper. Micronized copper is a recent form of antifouling wood preservative containing nanosized copper particles for use in pressure-treated lumber. The present study investigated the concentrations released and the release rate of total copper over the course of 133 d under freshwater, estuarine, and marine salinity conditions (0, 1, 10, and 30‰) for several commercially available pressure-treated lumbers: micronized copper azole (MCA) at 0.96 and 2.4 kg/m3 , alkaline copper quaternary (ACQ) at 0.30 and 9.6 kg/m3 , and chromated copper arsenate (CCA) at 40 kg/m3 . Lumber was tested as blocks and as sawdust. Overall, copper was released from all treated lumber samples. Under leaching conditions, total release ranged from 2 to 55% of the measured copper originally in the lumber, with release rate constants from the blocks of 0.03 to 2.71 (units per day). Generally, measured release and modeled equilibrium concentrations were significantly higher in the estuarine conditions compared with freshwater or marine salinities, whereas rate constants showed very limited differences between salinities. Furthermore, organic carbon was released during the leaching and demonstrated a significant relationship with released copper concentrations as a function of salinity. The results indicate that copper is released into estuarine/marine waters from multiple wood treatments including lumber amended with nanoparticle-sized copper. Environ Toxicol Chem 2018;37:1956-1968. Published 2018 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.
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Affiliation(s)
- Ashley N Parks
- Southern California Coastal Water Research Project, Costa Mesa, CA, USA
| | - Mark G Cantwell
- U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
| | - David R Katz
- U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
| | - Michaela A Cashman
- University of Rhode Island, Department of Geosciences, Kingston, RI, USA
| | - Todd P Luxton
- U.S. EPA, ORD/NRMRL, Land Remediation and Pollution Control Division, Division, Cincinnati, OH, USA
| | - Kay T Ho
- U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
| | - Robert M Burgess
- U.S. EPA, ORD/NHEERL, Atlantic Ecology Division, Narragansett, RI, USA
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21
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Karna RR, Noerpel MR, Luxton TP, Scheckel KG. Point of zero charge: Role in pyromorphite formation and bioaccessibility of lead and arsenic in phosphate amended soils. Soil Syst 2018; 2:22. [PMID: 30714024 DOI: 10.3390/soilsystems2020022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Soluble lead (Pb) can be immobilized in pure systems as pyromorphite by adding sources of phosphorus (P), but uncertainties still remain in natural systems. Knowledge of PZC is important to predict the ionization of functional groups and their interaction with metal species in solution. This study utilized the Pb- and As-contaminated soils to determine the combined effect of pH with respect to PZC and different rates of P-application on pyromorphite formation, and Pb and arsenic (As) bioaccessibility as impacted by speciation changes. Solution chemistry analysis along with synchrotron-based Pb- and As-speciation, and bioaccessibility treatment effect ratios (TERs) were conducted. Results indicated no significant effect of PZC on pyromorphite formation in P-amended soils; however, the TERPb appeared significantly lower at pH>pHPZC and higher at pH<pHPZC (α = 0.05). In contrast, the TERAs was significantly higher at pH>pHPZC, compared to the other two treatments, for the tested soils. The lack of conversion of soil Pb to pyromorphite may be attributed to presence of stable minerals limiting soluble-Pb availability and high organic matter content of the tested soils.
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Affiliation(s)
- Ranju R Karna
- Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee, USA
- United States Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH 45224, USA
| | - Matthew R Noerpel
- Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee, USA
- United States Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH 45224, USA
| | - Todd P Luxton
- United States Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH 45224, USA
| | - Kirk G Scheckel
- United States Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH 45224, USA
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22
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Clar JG, Platten WE, Baumann EJ, Remsen A, Harmon SM, Bennett-Stamper CL, Thomas TA, Luxton TP. Dermal transfer and environmental release of CeO 2 nanoparticles used as UV inhibitors on outdoor surfaces: Implications for human and environmental health. Sci Total Environ 2018; 613-614:714-723. [PMID: 28938214 PMCID: PMC6738344 DOI: 10.1016/j.scitotenv.2017.09.050] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [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: 08/01/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 05/30/2023]
Abstract
A major area of growth for "nano-enabled" consumer products have been surface coatings, including paints stains and sealants. Ceria (CeO2) nanoparticles (NPs) are of interest as they have been used as additives in these these products to increase UV resistance. Currently, there is a lack of detailed information on the potential release, and speciation (i.e., ion vs. particle) of CeO2 NPs used in consumer-available surface coatings during intended use scenarios. In this study, both Micronized-Copper Azole pressure-treated lumber (MCA), and a commercially available composite decking were coated with CeO2 NPs dispersed in Milli-Q water or wood stain. Coated surfaces were divided into two groups. The first was placed outdoors to undergo environmental weathering, while the second was placed indoors to act as experimental controls. Both weathered surfaces and controls were sampled over a period of 6months via simulated dermal contact using methods developed by the Consumer Product Safety Commission (CPSC). The size and speciation of material released was determined through sequential filtration, total metals analysis, X-Ray Absorption Fine Structure Spectroscopy, and electron microscopy. The total ceria release from MCA coated surfaces was found to be dependent on dispersion matrix with aqueous applications releasing greater quantities of CeO2 than stain based applications, 66±12mg/m2 and 36±7mg/m2, respectively. Additionally, a substantial quantity of CeO2 was reduced to Ce(III), present as Ce(III)-organic complexes, over the 6-month experimental period in aqueous based applications.
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Affiliation(s)
- Justin G Clar
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA; Oak Ridge Institute for Science and Education (ORISE), Postdoctoral Research Associate, USA
| | | | | | - Andrew Remsen
- Pegasus Technical Services Inc., Cincinnati, OH, USA
| | - Steve M Harmon
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA
| | - Christina L Bennett-Stamper
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA
| | - Treye A Thomas
- U.S. Consumer Product Safety Commission, Office of Hazard Identification and Reduction, 4330 East West Highway, Bethesda, MD 20814, USA
| | - Todd P Luxton
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA.
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23
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Favorito JE, Luxton TP, Eick MJ, Grossl PR. Selenium speciation in phosphate mine soils and evaluation of a sequential extraction procedure using XAFS. Environ Pollut 2017; 229:911-921. [PMID: 28781183 PMCID: PMC7363211 DOI: 10.1016/j.envpol.2017.07.071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [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: 03/09/2017] [Revised: 07/17/2017] [Accepted: 07/22/2017] [Indexed: 05/20/2023]
Abstract
Selenium is a trace element found in western US soils, where ingestion of Se-accumulating plants has resulted in livestock fatalities. Therefore, a reliable understanding of Se speciation and bioavailability is critical for effective mitigation. Sequential extraction procedures (SEP) are often employed to examine Se phases and speciation in contaminated soils but may be limited by experimental conditions. We examined the validity of a SEP using X-ray absorption spectroscopy (XAS) for both whole and a sequence of extracted soils. The sequence included removal of soluble, PO4-extractable, carbonate, amorphous Fe-oxide, crystalline Fe-oxide, organic, and residual Se forms. For whole soils, XANES analyses indicated Se(0) and Se(-II) predominated, with lower amounts of Se(IV) present, related to carbonates and Fe-oxides. Oxidized Se species were more elevated and residual/elemental Se was lower than previous SEP results from ICP-AES suggested. For soils from the SEP sequence, XANES results indicated only partial recovery of carbonate, Fe-oxide and organic Se. This suggests Se was incompletely removed during designated extractions, possibly due to lack of mineral solubilization or reagent specificity. Selenium fractions associated with Fe-oxides were reduced in amount or removed after using hydroxylamine HCl for most soils examined. XANES results indicate partial dissolution of solid-phases may occur during extraction processes. This study demonstrates why precautions should be taken to improve the validity of SEPs. Mineralogical and chemical characterizations should be completed prior to SEP implementation to identify extractable phases or mineral components that may influence extraction effectiveness. Sequential extraction procedures can be appropriately tailored for reliable quantification of speciation in contaminated soils.
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Affiliation(s)
- Jessica E Favorito
- Department of Crop and Soil Environmental Sciences, 185 Ag Quad Lane, 237 Smyth Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
| | - Todd P Luxton
- United States Environmental Protection Agency, National Risk Management Research Laboratory Land Remediation and Pollution Control Division, 5995 Center Hill Avenue, Cincinnati, OH 45243, USA.
| | - Matthew J Eick
- Department of Crop and Soil Environmental Sciences, 185 Ag Quad Lane, 237 Smyth Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
| | - Paul R Grossl
- Department of Plants, Soils, and Climate, 4820 Old Main Hill, Utah State University, Logan, UT 84322, USA.
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Eckley CS, Luxton TP, Goetz J, McKernan J. Water-level fluctuations influence sediment porewater chemistry and methylmercury production in a flood-control reservoir. Environ Pollut 2017; 222:32-41. [PMID: 28104341 PMCID: PMC6498431 DOI: 10.1016/j.envpol.2017.01.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [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: 10/28/2016] [Revised: 12/15/2016] [Accepted: 01/07/2017] [Indexed: 05/26/2023]
Abstract
Reservoirs typically have elevated fish mercury (Hg) levels compared to natural lakes and rivers. A unique feature of reservoirs is water-level management which can result in sediment exposure to the air. The objective of this study is to identify how reservoir water-level fluctuations impact Hg cycling, particularly the formation of the more toxic and bioaccumulative methylmercury (MeHg). Total-Hg (THg), MeHg, stable isotope methylation rates and several ancillary parameters were measured in reservoir sediments (including some in porewater and overlying water) that are seasonally and permanently inundated. The results showed that sediment and porewater MeHg concentrations were over 3-times higher in areas experiencing water-level fluctuations compared to permanently inundated sediments. Analysis of the data suggest that the enhanced breakdown of organic matter in sediments experiencing water-level fluctuations has a two-fold effect on stimulating Hg methylation: 1) it increases the partitioning of inorganic Hg from the solid phase into the porewater phase (lower log Kd values) where it is more bioavailable for methylation; and 2) it increases dissolved organic carbon (DOC) in the porewater which can stimulate the microbial community that can methylate Hg. Sulfate concentrations and cycling were enhanced in the seasonally inundated sediments and may have also contributed to increased MeHg production. Overall, our results suggest that reservoir management actions can have an impact on the sediment-porewater characteristics that affect MeHg production. Such findings are also relevant to natural water systems that experience wetting and drying cycles, such as floodplains and ombrotrophic wetlands.
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Affiliation(s)
- Chris S Eckley
- US Environmental Protection Agency, Region-10. 1200, 6th Ave Seattle, WA 98101, USA
| | - Todd P Luxton
- US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA.
| | - Jennifer Goetz
- US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
| | - John McKernan
- US Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA
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25
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Clar JG, Li X, Impellitteri CA, Bennett-Stamper C, Luxton TP. Copper Nanoparticle Induced Cytotoxicity to Nitrifying Bacteria in Wastewater Treatment: A Mechanistic Copper Speciation Study by X-ray Absorption Spectroscopy. Environ Sci Technol 2016; 50:9105-9113. [PMID: 27466862 DOI: 10.1021/acs.est.6b01910] [Citation(s) in RCA: 3] [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: 06/06/2023]
Abstract
With the inclusion of engineered nanomaterials in industrial processes and consumer products, wastewater treatment plants (WWTPs) could serve as a major sink for these emerging contaminants. Previous research has demonstrated that nanomaterials are potentially toxic to microbial communities utilized in biological wastewater treatment (BWT). Copper-based nanoparticles (CuNPs) are of particular interest based on their increasing use in wood treatment, paints, household products, coatings, and byproducts of semiconductor manufacturing. A critical step in BWT is nutrient removal through nitrification. This study examined the potential toxicity of uncoated and polyvinylpyrrolidone (PVP)-coated CuO, and Cu2O nanoparticles, as well as Cu ions to microbial communities responsible for nitrification in BWT. Inhibition was inferred from changes to the specific oxygen uptake rate (sOUR) in the absence and presence of Cu ions and CuNPs. X-ray absorption fine structure spectroscopy, with linear combination fitting (LCF), was utilized to track changes to Cu speciation throughout exposure. Results indicate that the dissolution of Cu ions from CuNPs drive microbial inhibition. The presence of a PVP coating on CuNPs has little effect on inhibition. LCF analysis of the biomass combined with metal partitioning analysis supports the current hypothesis that Cu-induced cytotoxicity is primarily caused by reactive oxygen species formed from ionic Cu in solution via catalytic reaction intermediated by reduced Cu(I) species.
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Affiliation(s)
- Justin G Clar
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, Ohio 45224, United States
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, Tennessee 37831, United States
| | - Xuan Li
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, Ohio 45224, United States
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, Tennessee 37831, United States
| | - Christopher A Impellitteri
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, Ohio 45224, United States
| | - Christina Bennett-Stamper
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, Ohio 45224, United States
| | - Todd P Luxton
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, 5995 Center Hill Avenue, Cincinnati, Ohio 45224, United States
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26
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Weber JS, Goyne KW, Luxton TP, Thompson AL. Phosphate Treatment of Lead-Contaminated Soil: Effects on Water Quality, Plant Uptake, and Lead Speciation. J Environ Qual 2015; 44:1127-1136. [PMID: 26437094 DOI: 10.2134/jeq2014.10.0447] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Water quality threats associated with using phosphate-based amendments to remediate Pb-contaminated soils are a concern, particularly in riparian areas. This study investigated the effects of P application rates to a Pb-contaminated alluvial soil on Pb and P loss via surface water runoff, Pb accumulation in tall fescue ( Schreb; Kentucky 31), and Pb speciation. An alluvial soil was treated with triple superphosphate at P to Pb molar ratios of 0:1 (control), 4:1, 8:1, and 16:1. After a 6-mo reaction period, rainfall simulation (RFS) studies were conducted, followed by tall fescue establishment and a second set of RFS studies (1 yr after treatment). Results from the first RFS study (unvegetated) demonstrated that the total Pb and P concentrations in the effluents of 8:1 and 16:1 (P:Pb molar ratio) treatment levels were significantly greater ( < 0.05) than the control. One year after P treatment and 6 mo after vegetation establishment, total P and Pb concentrations of the effluents from a second RFS decreased by one to three orders of magnitude. Total and dissolved P concentration in runoff from the 16:1 P:Pb treatment remained significantly greater than all other treatments. However, total Pb concentration in the runoff was comparable among the treatments. Phosphorus treatment also reduced Pb uptake into tall fescue by >55%. X-ray absorption near-edge structure spectroscopy data showed that pyromorphite [Pb(PO)OH,Cl,F] abundance ranged from 0% (control) to 32% (16:1 P:Pb; 1 yr after treatment) of the total soil Pb. Although P treatment stimulated pyromorphite formation, pyromorphite abundance was comparable between the P-treated soils. These findings suggest that a 4:1 (P:Pb molar ratio) P treatment may be a sufficient means of reducing Pb bioavailability while minimizing concerns related to P loss in an alluvial setting.
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27
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Impellitteri CA, Harmon S, Silva RG, Miller BW, Scheckel KG, Luxton TP, Schupp D, Panguluri S. Transformation of silver nanoparticles in fresh, aged, and incinerated biosolids. Water Res 2013; 47:3878-3886. [PMID: 23561507 DOI: 10.1016/j.watres.2012.12.041] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 10/01/2012] [Accepted: 12/03/2012] [Indexed: 06/02/2023]
Abstract
The purpose of this research was to assess the chemical transformation of silver nanoparticles (AgNPs) in aged, fresh, and incinerated biosolids in order to provide information for AgNP life cycle analyses. Silver nanoparticles were introduced to the influent of a pilot-scale wastewater (WW) treatment system consisting of a primary clarifier (PC), aeration basin, and secondary clarifier. The partitioning of the AgNPs between the aqueous and solid phases in the system was monitored. Less than 3% of the total AgNPs introduced into the PC were measured at the overflow of the PC. Biosolids were collected from the pilot-scale system for silver analyses, including Ag concentration and speciation. Additionally, biosolids were collected from a publically owned treatment works (POTW). The POTW biosolids were spiked with AgNPs, AgNO3, and Ag2S. One set of the spiked POTW biosolids was aged for one month, and another set was analyzed within 24 h via X-ray absorption spectroscopy (XAS) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDX) in order to determine Ag chemical speciation and elemental associations. Replicates of the aged and 24-h samples were also incinerated at 850 °C for 4 h. The residual ash was analyzed by XAS and SEM-EDX. The results show that AgNPs are converted to Ag-sulfur (as sulfide and sulfhydryl) species in fresh and aged biosolids, which is in agreement with other studies on AgNPs in biosolids. Results from linear combination fitting of the XAS data for incinerated biosolids show that a significant proportion of the spiked silver (30-50%) is converted to elemental Ag in the incineration process. In addition to elemental Ag, the results suggest the presence of additional Ag-S complexes such as Ag2SO4 (up to 25%), and silver associated with sulfhydryl groups (26-50%) in the incinerated biosolids. Incinerated biosolids spiked with AgNO3 and Ag2S exhibited similar transformations. These transformations of AgNPs should be accounted for in life-cycle analyses of AgNPs and in management decisions regarding the disposal of incinerated biosolids.
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Affiliation(s)
- Christopher A Impellitteri
- United States Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA.
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Gerke TL, Little BJ, Luxton TP, Scheckel KG, Maynard JB. Strontium concentrations in corrosion products from residential drinking water distribution systems. Environ Sci Technol 2013; 47:5171-7. [PMID: 23600992 DOI: 10.1021/es4000609] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The United States Environmental Protection Agency (US EPA) will require some U.S. drinking water distribution systems (DWDS) to monitor nonradioactive strontium (Sr(2+)) in drinking water in 2013. Iron corrosion products from four DWDS were examined to assess the potential for Sr(2+) binding and release. Average Sr(2+) concentrations in the outermost layer of the corrosion products ranged from 3 to 54 mg kg(-1) and the Sr(2+) drinking water concentrations were all ≤0.3 mg L(-1). Micro-X-ray adsorption near edge structure spectroscopy and linear combination fitting determined that Sr(2+) was principally associated with CaCO3. Sr(2+) was also detected as a surface complex associated with α-FeOOH. Iron particulates deposited on a filter inside a home had an average Sr(2+) concentration of 40.3 mg kg(-1) and the associated drinking water at a tap was 210 μg L(-1). The data suggest that elevated Sr(2+) concentrations may be associated with iron corrosion products that, if disturbed, could increase Sr(2+) concentrations above the 0.3 μg L(-1) US EPA reporting threshold. Disassociation of very small particulates could result in drinking water Sr(2+) concentrations that exceed the US EPA health reference limit (4.20 mg kg(-1) body weight).
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Affiliation(s)
- Tammie L Gerke
- Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221-0013, United States.
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Ford RG, Acree SD, Lien BK, Scheckel KG, Luxton TP, Ross RR, Williams AG, Clark P. Delineating landfill leachate discharge to an arsenic contaminated waterway. Chemosphere 2011; 85:1525-1537. [PMID: 22018591 DOI: 10.1016/j.chemosphere.2011.09.046] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 09/10/2011] [Accepted: 09/12/2011] [Indexed: 05/27/2023]
Abstract
Discharge of contaminated ground water may serve as a primary and on-going source of contamination to surface water. A field investigation was conducted at a Superfund site in Massachusetts, USA to define the locus of contaminant flux and support source identification for arsenic contamination in a pond abutting a closed landfill. Subsurface hydrology and ground-water chemistry were evaluated in the aquifer between the landfill and the pond during the period 2005-2009 employing a network of wells to delineate the spatial and temporal variability in subsurface conditions. These observations were compared with concurrent measures of ground-water seepage and surface water chemistry within a shallow cove that had a historical visual record of hydrous ferric oxide precipitation along with elevated arsenic concentrations in shallow sediments. Barium, presumably derived from materials disposed in the landfill, served as an indicator of leachate-impacted ground water discharging into the cove. Evaluation of the spatial distributions of seepage flux and the concentrations of barium, calcium, and ammonium-nitrogen indicated that the identified plume primarily discharged into the central portion of the cove. Comparison of the spatial distribution of chemical signatures at depth within the water column demonstrated that direct discharge of leachate-impacted ground water was the source of highest arsenic concentrations observed within the cove. These observations demonstrate that restoration of the impacted surface water body will necessitate control of leachate-impacted ground water that continues to discharge into the cove.
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Affiliation(s)
- Robert G Ford
- National Risk Management Research Laboratory, US Environmental Protection Agency, Office of Research and Development, 26 W Martin Luther King Dr., Cincinnati, OH 45268, USA.
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30
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El Badawy AM, Luxton TP, Silva RG, Scheckel KG, Suidan MT, Tolaymat TM. Impact of environmental conditions (pH, ionic strength, and electrolyte type) on the surface charge and aggregation of silver nanoparticles suspensions. Environ Sci Technol 2010; 44:1260-6. [PMID: 20099802 DOI: 10.1021/es902240k] [Citation(s) in RCA: 653] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The impact of capping agents and environmental conditions (pH, ionic strength, and background electrolytes) on surface charge and aggregation potential of silver nanoparticles (AgNPs) suspensions were investigated. Capping agents are chemicals used in the synthesis of nanoparticles to prevent aggregation. The AgNPs examined in the study were as follows: (a) uncoated AgNPs (H(2)-AgNPs), (b) electrostatically stabilized (citrate and NaBH(4)-AgNPs), (c) sterically stabilized (polyvinylpyrrolidone (PVP)-AgNPs), and (d) electrosterically stabilized (branched polyethyleneimine (BPEI)-AgNPs)). The uncoated (H(2)-AgNPs), the citrate, and NaBH(4)-coated AgNPs aggregated at higher ionic strengths (100 mM NaNO(3)) and/or acidic pH (3.0). For these three nanomaterials, chloride (Cl(-), 10 mM), as a background electrolyte, resulted in a minimal change in the hydrodynamic diameter even at low pH (3.0). This was limited by the presence of residual silver ions, which resulted in the formation of stable negatively charged AgCl colloids. Furthermore, the presence of Ca(2+) (10 mM) resulted in aggregation of the three previously identified AgNPs regardless of the pH. As for PVP coated AgNPs, the ionic strength, pH and electrolyte type had no impact on the aggregation of the sterically stabilized AgNPs. The surface charge and aggregation of the BPEI coated AgNPs varied according to the solution pH.
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Affiliation(s)
- Amro M El Badawy
- Department of Civil & Environmental Engineering, University of Cincinnati, Cincinnati, OH, USA
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31
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Scheckel KG, Luxton TP, El Badawy AM, Impellitteri CA, Tolaymat TM. Synchrotron speciation of silver and zinc oxide nanoparticles aged in a kaolin suspension. Environ Sci Technol 2010; 44:1307-1312. [PMID: 20078035 DOI: 10.1021/es9032265] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Assessments of the environmental fate and mobility of nanoparticles must consider the behavior of nanoparticles in relevant environmental systems that may result in speciation changes over time. Environmental conditions may act on nanoparticles to change their size, shape, and surface chemistry. Changing these basic characteristics of nanoparticles may result in a final reaction product that is significantly different than the initial nanomaterial. As such, basing long-term risk and toxicity on the initial properties of a nanomaterial may lead to erroneous conclusions if nanoparticles change upon release to the environment. The influence of aging on the speciation and chemical stability of silver and zinc oxide nanoparticles in kaolin suspensions was examined in batch reactors for up to 18 months. Silver nanoparticles remained unchanged in sodium nitrate suspensions; however, silver chloride was identified with the metallic silver nanoparticles in sodium chloride suspensions and may be attributed to an in situ silver chloride surface coating. Zinc oxide nanoparticles were rapidly converted via destabilization/dissolution mechanisms to Zn(2+) inner-sphere sorption complexes within 1 day of reaction and these sorption complexes were maintained through the 12 month aging processes. Chemical and physical alteration of nanomaterials in the environment must be examined to understand fate, mobility, and toxicology.
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Affiliation(s)
- Kirk G Scheckel
- U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA.
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Tolaymat TM, El Badawy AM, Genaidy A, Scheckel KG, Luxton TP, Suidan M. An evidence-based environmental perspective of manufactured silver nanoparticle in syntheses and applications: a systematic review and critical appraisal of peer-reviewed scientific papers. Sci Total Environ 2010; 408:999-1006. [PMID: 19945151 DOI: 10.1016/j.scitotenv.2009.11.003] [Citation(s) in RCA: 389] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 10/20/2009] [Accepted: 11/02/2009] [Indexed: 05/18/2023]
Abstract
BACKGROUND Most recently, renewed interest has arisen in manufactured silver nanomaterials because of their unusually enhanced physicochemical properties and biological activities compared to the bulk parent materials. A wide range of applications has emerged in consumer products ranging from disinfecting medical devices and home appliances to water treatment. Because the hypothesized mechanisms that govern the fate and transport of bulk materials may not directly apply to materials at the nanoscale, there are great concerns in the regulatory and research communities about potential environmental impacts associated with the use of silver nanoparticles. In particular, the unlimited combinations of properties emerging from the syntheses and applications of silver nanoparticles are presenting an urgent need to document the predominant salt precursors, reducing agents and stabilizing agents utilized in the synthesis processes of silver nanoparticles to guide the massive efforts required for environmental risk assessment and management. OBJECTIVES The primary objective of this study is to present an evidence-based environmental perspective of silver nanoparticle properties in syntheses and applications. The following specific aims are designed to achieve the study objective: Aim 1--to document the salt precursors and agents utilized in synthesizing silver nanoparticles; Aim 2--to determine the characteristics of silver nanoparticles currently in use in the scientific literature when integrated in polymer matrices to form nanocomposites and combined with other metal nanoparticles to form bimetallic nanoparticles; Aim 3--to provide a summary of the morphology of silver nanoparticles; and (4) Aim 4--to provide an environmental perspective of the evidence presented in Aims 1 to 3. METHODS A comprehensive electronic search of scientific databases was conducted in support of the study objectives. Specific inclusion criteria were applied to gather the most pertinent research articles. Data and information extraction relied on the type of synthesis methods, that is, synthesized silver nanoparticles in general and specific applications, nanocomposites, and bimetallic techniques. The following items were gathered for: type of silver salt, solvent, reducing agent, stabilizing agent, size, and type of application/nanocomposite/bimetallic, and template (for nanocomposites). The description of evidence was presented in tabular format. The critical appraisal was analyzed in graphical format and discussed. RESULTS An analysis of the scientific literature suggests that most synthesis processes produce spherical silver nanoparticles with less than 20nm diameter. Silver nanoparticles are often synthesized via reduction of AgNO(3), dissolution in water, and utilization of reductants also acting as capping or stabilizing agents for the control of particle size to ensure a relatively stable suspension. Two of the most commonly used reductants and stabilizing agents are NaBH(4) and citrate which yield particles with a negative surface charge over the environmental pH range (3-10). The environmental perspectives of these parameters are discussed. CONCLUDING REMARKS It is expected that the antibacterial property of bulk silver is carried over and perhaps enhanced, to silver nanoparticles. Therefore, when one examines the environmental issues associated with the manufacture and use of silver nanoparticle-based products, the antibacterial effects should always be taken into account particularly at the different stages of the product lifecycle. Currently, there are two arguments in the scientific literature about the mechanisms of antimicrobial properties of silver nanoparticles as they relate to colloidal silver particles and inonic silver. Methodologies of risk assessment and control have to account for both arguments.
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Affiliation(s)
- Thabet M Tolaymat
- USEPA Office of Research and Development, National Risk Management Laboratory, 26 West Martin Luther King Drive, Cincinnati, OH 45224, United States.
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Abstract
The adsorption of chromate on mineral surfaces has received much attention due to its toxicity in natural systems. Spectroscopic studies have demonstrated that chromate forms inner-sphere complexes on variable-charge surfaces. However, in natural systems chromate has been observed to be fairly mobile, which has been explained by the presence of naturally occurring ligands competing with chromate for mineral surface sites. Silicic acid is a ubiquitous ligand in soil and water environments and also sorbs strongly to variable-charge surfaces. Yet little research has examined its influence on chromate adsorption to variable-charge surfaces such as goethite. This study examined the influence of silicic acid (0.10 and 1.0 mM) on the adsorption kinetics of chromate (0.05 and 0.10 mM) on goethite over a range of common soil pH values (4, 6, and 8). The rate and total quantity of chromate adsorption decreased in all the experiments except at a pH value of 4 and a chromate concentration of 0.05 mM. The inhibition of chromate adsorption ranged from 3.1% (pH = 4, Si = 0.10 mM, chromate = 0.10 mM) to 83.3% (pH = 8, Si = 1.0 mM, chromate = 0.05 mM). The rate of chromate adsorption decreased with an increase in pH and silicic acid concentration. This was attributed to a reduction in the surface potential of goethite on silicic acid adsorption as well as a competition for surface sites. The presence of naturally occurring ligands such as silicic acid may be responsible for the enhanced mobility of chromate in natural systems and demonstrates the importance of competitive adsorption for evaluating the mobility of trace elements.
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Affiliation(s)
- Stephanie M Garman
- Department of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, USA
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