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O’Day PA, Pattammattel A, Aronstein P, Leppert VJ, Forman HJ. Iron Speciation in Respirable Particulate Matter and Implications for Human Health. Environ Sci Technol 2022; 56:7006-7016. [PMID: 35235749 PMCID: PMC9179659 DOI: 10.1021/acs.est.1c06962] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 01/19/2022] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
Particulate matter (PM) air pollution poses a major global health risk, but the role of iron (Fe) is not clearly defined because chemistry at the particle-cell interface is often not considered. Detailed spectromicroscopy characterizations of PM2.5 samples from the San Joaquin Valley, CA identified major Fe-bearing components and estimated their relative proportions. Iron in ambient PM2.5 was present in spatially and temporally variable mixtures, mostly as Fe(III) oxides and phyllosilicates, but with significant fractions of metallic iron (Fe(0)), Fe(II,III) oxide, and Fe(III) bonded to organic carbon. Fe(0) was present as aggregated, nm-sized particles that comprised up to ∼30% of the Fe spectral fraction. Mixtures reflect anthropogenic and geogenic particles subjected to environmental weathering, but reduced Fe in PM originates from anthropogenic sources, likely as abrasion products. Possible mechanistic pathways involving Fe(0) particles and mixtures of Fe(II) and Fe(III) surface species may generate hydrogen peroxide and oxygen-centered radical species (hydroxyl, hydroperoxyl, or superoxide) in Fenton-type reactions. From a health perspective, PM mixtures with reduced and oxidized Fe will have a disproportionate effect in cellular response after inhalation because of their tendency to shuttle electrons and produce oxidants and electrophiles that induce inflammation and oxidative stress.
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Affiliation(s)
- Peggy A. O’Day
- Life
and Environmental Sciences Department and the Sierra Nevada Research
Institute, University of California, Merced, California 95343, United States
- Environmental
Systems Graduate Program, University of
California, Merced, 95343, United States
| | - Ajith Pattammattel
- Life
and Environmental Sciences Department and the Sierra Nevada Research
Institute, University of California, Merced, California 95343, United States
- NSLS
II, Brookhaven National Laboratory, Upton, New York 11973 United States
| | - Paul Aronstein
- Environmental
Systems Graduate Program, University of
California, Merced, 95343, United States
| | - Valerie J. Leppert
- Materials
Science and Engineering Department, University
of California, Merced, California 95343, United States
| | - Henry Jay Forman
- Life
and Environmental Sciences Department and the Sierra Nevada Research
Institute, University of California, Merced, California 95343, United States
- Leonard
Davis School of Gerontology, University
of Southern California, Los Angeles, California 90089, United States
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Pattammattel A, Leppert VJ, Aronstein P, Robinson M, Mousavi A, Sioutas C, Forman HJ, O’Day PA. Iron Speciation in Particulate Matter (PM 2.5) from Urban Los Angeles Using Spectro-microscopy Methods. Atmos Environ (1994) 2021; 245:117988. [PMID: 33223923 PMCID: PMC7673293 DOI: 10.1016/j.atmosenv.2020.117988] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The speciation, oxidation states, and relative abundance of iron (Fe) phases in PM2.5 samples from two locations in urban Los Angeles were investigated using a combination of bulk and spatially resolved, element-specific spectroscopy and microscopy methods. Synchrotron X-ray absorption spectroscopy (XAS) of bulk samples in situ (i.e., without extraction or digestion) was used to quantify the relative fractions of major Fe phases, which were corroborated by spatially resolved spectro-microscopy measurements. Ferrihydrite (amorphous Fe(III)-hydroxide) comprised the largest Fe fraction (34-52%), with hematite (α-Fe2O3; 13-23%) and magnetite (Fe3O4; 10-24%) identified as major crystalline oxide components. An Fe-bearing phyllosilicate fraction (16-23%) was fit best with a reference spectrum of a natural illite/smectite mineral, and metallic Fe(0) was a relatively small (2-6%) but easily identified component. Sizes, morphologies, oxidation state, and trace element compositions of Fe-bearing PM from electron microscopy, electron energy loss spectroscopy (EELS), and scanning transmission X-ray microscopy (STXM) revealed variable and heterogeneous mixtures of Fe species and phases, often associated with carbonaceous material with evidence of surface oxidation. Ferrihydrite (or related Fe(III) hydroxide phases) was ubiquitous in PM samples. It forms as an oxidation or surface alteration product of crystalline Fe phases, and also occurs as coatings or nanoparticles dispersed with other phases as a result of environmental dissolution and re-precipitation reactions. The prevalence of ferrihydrite (and adsorbed Fe(III) has likely been underestimated in studies of ambient PM because it is non-crystalline, non-magnetic, more soluble than crystalline phases, and found in complex mixtures. Review of potential sources of different particle types suggests that the majority of Fe-bearing PM from these urban sites originates from anthropogenic activities, primarily abrasion products from vehicle braking systems and engine emissions from combustion and/or wear. These variable mixtures have a high probability for electron transfer reactions between Fe, redox-active metals such as copper, and reactive carbon species such as quinones. Our findings suggest the need to assess biological responses of specific Fe-bearing phases both individually and in combination to unravel mechanisms of adverse health effects of particulate Fe.
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Affiliation(s)
- Ajith Pattammattel
- Sierra Nevada Research Institute and School of Natural Sciences, University of California, Merced, 95343, USA
| | | | - Paul Aronstein
- Environmental Systems Program, University of California, Merced, 95343, USA
| | - Matthew Robinson
- School of Engineering, University of California, Merced, 95343, USA
| | - Amirhosein Mousavi
- Viterbi School of Engineering, University of Southern California, Los Angeles, USA
| | - Constantinos Sioutas
- Viterbi School of Engineering, University of Southern California, Los Angeles, USA
| | - Henry Jay Forman
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, USA
| | - Peggy A. O’Day
- Sierra Nevada Research Institute and School of Natural Sciences, University of California, Merced, 95343, USA
- Environmental Systems Program, University of California, Merced, 95343, USA
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Pattammattel A, Leppert VJ, Forman HJ, O’Day PA. Surface characterization and chemical speciation of adsorbed iron(iii) on oxidized carbon nanoparticles. Environ Sci Process Impacts 2019; 21:548-563. [PMID: 30702742 PMCID: PMC6426675 DOI: 10.1039/c8em00545a] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Carbonaceous nanomaterials represent a significant portion of ultra-fine airborne particulate matter, and iron is the most abundant transition metal in air particles. Owing to their high surface area and atmospheric oxidation, carbon nanoparticles (CNP) are enriched with surface carbonyl functional groups and act as a host for metals and small molecules. Using a synthetic model, concentration-dependent changes in the chemical speciation of iron adsorbed on oxidized carbon surfaces were investigated by a combination of X-ray and electron microscopic and spectroscopic methods. Carbon K-edge absorption spectra demonstrated that the CNP surface was enriched with carboxylic acid groups after chemical oxidation but that microporosity was unchanged. Oxidized CNP showed a high affinity for sorption of Fe(iii) from solution (75-95% uptake) and spectroscopic measurements confirmed a 3+ oxidation state of Fe on CNP irrespective of surface loading. The bonding of adsorbed Fe(iii) at variable loadings was determined by iron K-edge X-ray absorption spectroscopy. At low loadings (3 and 10 μmol Fe m-2 CNP), mononuclear Fe was octahedrally coordinated to oxygen atoms of carboxylate groups. As Fe surface coverage increased (21 and 31 μmol Fe m-2 CNP), Fe-Fe backscatters were observed at interatomic distances indicating iron (oxy)hydroxide particle formation on CNP. Electron-donating surface carboxylate groups on CNP coordinated and stabilized mononuclear Fe(iii). Saturation of high-affinity sites may have promoted hydroxide particle nucleation at higher loading, demonstrating that the chemical form of reactive metal ions may change with surface concentration and degree of CNP surface oxidation. Model systems such as those discussed here, with controlled surface properties and known chemical speciation of adsorbed metals, are needed to establish structure-activity models for toxicity assessments of environmentally relevant nanoparticles.
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Affiliation(s)
- Ajith Pattammattel
- School of Natural Sciences and Sierra Nevada Research Institute, University of California, Merced, California, USA
- Corresponding authors ,
| | - Valerie J. Leppert
- School of Engineering, University of California, Merced, California, USA
| | - Henry Jay Forman
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
| | - Peggy A. O’Day
- School of Natural Sciences and Sierra Nevada Research Institute, University of California, Merced, California, USA
- Corresponding authors ,
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Gomez-Gonzalez MA, Bolea E, O’Day PA, Garcia-Guinea J, Garrido F, Laborda F. Combining single-particle inductively coupled plasma mass spectrometry and X-ray absorption spectroscopy to evaluate the release of colloidal arsenic from environmental samples. Anal Bioanal Chem 2016; 408:5125-35. [DOI: 10.1007/s00216-016-9331-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 01/05/2016] [Accepted: 01/12/2016] [Indexed: 10/22/2022]
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Bessinger BA, Vlassopoulos D, Serrano S, O’Day PA. Reactive Transport Modeling of Subaqueous Sediment Caps and Implications for the Long-Term Fate of Arsenic, Mercury, and Methylmercury. Aquat Geochem 2012; 18:297-326. [PMID: 27110214 PMCID: PMC4802735 DOI: 10.1007/s10498-012-9165-4] [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: 11/09/2011] [Accepted: 02/28/2012] [Indexed: 05/04/2023]
Abstract
A 1-D biogeochemical reactive transport model with a full set of equilibrium and kinetic biogeochemical reactions was developed to simulate the fate and transport of arsenic and mercury in subaqueous sediment caps. Model simulations (50 years) were performed for freshwater and estuarine scenarios with an anaerobic porewater and either a diffusion-only or a diffusion plus 0.1-m/year upward advective flux through the cap. A biological habitat layer in the top 0.15 m of the cap was simulated with the addition of organic carbon. For arsenic, the generation of sulfate-reducing conditions limits the formation of iron oxide phases available for adsorption. As a result, subaqueous sediment caps may be relatively ineffective for mitigating contaminant arsenic migration when influent concentrations are high and sorption capacity is insufficient. For mercury, sulfate reduction promotes the precipitation of metacinnabar (HgS) below the habitat layer, and associated fluxes across the sediment-water interface are low. As such, cap thickness is a key design parameter that can be adjusted to control the depth below the sediment-water interface at which mercury sulfide precipitates. The highest dissolved methylmercury concentrations occur in the habitat layer in estuarine environments under conditions of advecting porewater, but the highest sediment concentrations are predicted to occur in freshwater environments due to sorption on sediment organic matter. Site-specific reactive transport simulations are a powerful tool for identifying the major controls on sediment- and porewater-contaminant arsenic and mercury concentrations that result from coupling between physical conditions and biologically mediated chemical reactions.
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Affiliation(s)
- Brad A. Bessinger
- S.S. Papadopulos and Associates, 19215 SE 34th St., Suite 106-370, Camas, WA 98607 USA
| | | | - Susana Serrano
- School of Natural Sciences, University of California, 5200 North Lake Rd, Merced, CA 95343 USA
- Present Address: Institute for Agricultural Sciences, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 115-dup, 28006 Madrid, Spain
| | - Peggy A. O’Day
- School of Natural Sciences, University of California, 5200 North Lake Rd, Merced, CA 95343 USA
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Hayes SM, O’Day PA, Webb SM, Maier RM, Chorover J. Changes in zinc speciation with mine tailings acidification in a semiarid weathering environment. Environ Sci Technol 2011; 45:7166-72. [PMID: 21761897 PMCID: PMC3175378 DOI: 10.1021/es201006b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
High concentrations of residual metal contaminants in mine tailings can be transported easily by wind and water, particularly when tailings remain unvegetated for decades following mining cessation, as is the case in semiarid landscapes. Understanding the speciation and mobility of contaminant metal(loid)s, particularly in surficial tailings, is essential to controlling their phytotoxicities and to revegetating impacted sites. In prior work, we showed that surficial tailings samples from the Klondyke State Superfund Site (AZ, USA), ranging in pH from 5.4 to 2.6, represent a weathering series, with acidification resulting from sulfide mineral oxidation, long-term Fe hydrolysis, and a concurrent decrease in total (6000 to 450 mg kg(-1)) and plant-available (590 to 75 mg kg(-1)) Zn due to leaching losses and changes in Zn speciation. Here, we used bulk and microfocused Zn K-edge X-ray absorption spectroscopy (XAS) data and a six-step sequential extraction procedure to determine tailings solid phase Zn speciation. Bulk sample spectra were fit by linear combination using three references: Zn-rich phyllosilicate (Zn(0.8)talc), Zn sorbed to ferrihydrite (Zn(adsFeOx)), and zinc sulfate (ZnSO(4) · 7H(2)O). Analyses indicate that Zn sorbed in tetrahedral coordination to poorly crystalline Fe and Mn (oxyhydr)oxides decreases with acidification in the weathering sequence, whereas octahedral zinc in sulfate minerals and crystalline Fe oxides undergoes a relative accumulation. Microscale analyses identified hetaerolite (ZnMn(2)O(4)), hemimorphite (Zn(4)Si(2)O(7)(OH)(2) · H(2)O) and sphalerite (ZnS) as minor phases. Bulk and microfocused spectroscopy complement the chemical extraction results and highlight the importance of using a multimethod approach to interrogate complex tailings systems.
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Affiliation(s)
- Sarah M. Hayes
- Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721
| | - Peggy A. O’Day
- School of Natural Sciences, University of California, Merced, CA 95343, USA
| | - Sam M. Webb
- Stanford Synchrotron Radiation Laboratory, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, MS 69, Menlo Park, California 94025
| | - Raina M. Maier
- Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721
| | - Jon Chorover
- Department of Soil, Water and Environmental Science, University of Arizona, Tucson, AZ 85721
- Corresponding author ; phone: 520-626-5635; fax: 520-621-1647
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Abstract
Amending soils with mineral-based materials to immobilize contaminants is both old and new. Although mineral amendments have been used for decades in agriculture, new applications with a variety of natural and reprocessed materials are emerging. By sequestering contaminants in or on solid phases and reducing their ability to partition into water or air, amendments can reduce the risk of exposure to humans or biota. A variety of mineral types are commonly used to amend contaminated soils, with different modes of molecular-scale sequestration. Regulatory, social, and economic factors also influence decisions to employ mineral amendments as a treatment technology.
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Affiliation(s)
- Peggy A. O’Day
- School of Natural Sciences, University of California, Merced, CA 95343, USA
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