An Experimental Protocol for Structural Characterization of Fe in Dilute Natural Waters

Sundman, Anneli; Karlsson, Torbjörn; Persson, Per

doi:10.1021/es304630a

Cited by 13 publications

(25 citation statements)

References 39 publications

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“…This showed that a large fraction of Fe was associated with negatively charged NOM. The extent of Fe adsorption was in line with previous studies (Sundman et al, 2013(Sundman et al, , 2014a, which also have shown that adsorption of Fe-NOM species onto the resins was partly selective favouring for example Fe(III)-NOM over Fe(II)-NOM. Concomitantly, the percentage of As adsorption remained constant at 85% in the As-spiked samples (Table 1) implying that the Fe to As molar ratio on the resins decreased with increasing As concentrations.…”

Section: Resultssupporting

confidence: 91%

“…Three of these were spiked with As(V) to final Fe/As molar ratios of 15.6, 4.0 and 2.0, respectively. The As(V)-spiked samples were equilibrated, at room temperature, for 24 h prior to pre-concentration via addition of ion exchange resins (Dowex 1 Â 8, chloride form, Sigma Aldrich), according to the experimental protocol described in Sundman et al (2013). All samples were covered with aluminum foil and manually rotated on a regular basis for 5 days.…”

Section: Chemicals and Sample Preparationmentioning

confidence: 99%

“…As a result, Fe speciation in natural waters has received increased attention over the last years, e.g. Ingri et al (2006), Kleja et al (2012), Ilina et al (2013), Neubauer et al (2013), Sjöstedt et al (2013) and Sundman et al (2013Sundman et al ( , 2014a. A growing pool of evidence suggests that Fe speciation in oxygenated, aquatic systems can be divided into two main categories; organically complexed Fe(III)/Fe(II) and Fe(III) (hydr)oxides (Karlsson and Persson, 2012;Neubauer et al, 2013;Sjöstedt et al, 2013;Sundman et al, 2013Sundman et al, , 2014a.…”

Section: Introductionmentioning

confidence: 99%

“…Ingri et al (2006), Kleja et al (2012), Ilina et al (2013), Neubauer et al (2013), Sjöstedt et al (2013) and Sundman et al (2013Sundman et al ( , 2014a. A growing pool of evidence suggests that Fe speciation in oxygenated, aquatic systems can be divided into two main categories; organically complexed Fe(III)/Fe(II) and Fe(III) (hydr)oxides (Karlsson and Persson, 2012;Neubauer et al, 2013;Sjöstedt et al, 2013;Sundman et al, 2013Sundman et al, , 2014a. The limited solubility of Fe(III) (hydr)oxides indicates that they should be the predominant form of Fe at environmentally relevant conditions, but these solid phases can be dissolved via complexation by NOM, and both Fe(III) and Fe(II) may be stabilized as organic complexes Persson, 2010, 2012;Neubauer et al, 2013;Sundman et al, 2014a).…”

Section: Introductionmentioning

confidence: 99%

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Reactivity of Fe from a natural stream water towards As(V)

Sundman

Karlsson

Persson

2015

Applied Geochemistry

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a b s t r a c tInteractions between iron (Fe) and arsenic (As) play a vital role in aquatic and terrestrial ecosystems influencing the reactivity and transport of arsenic. A key aspect is the effect of natural organic matter (NOM) on these interactions, and previous investigations have reported the existence of ternary AsFe-NOM species. In this study, the reactivity of Fe, from a boreal stream water, towards As(V) was investigated using Fe and As K-edge X-ray absorption spectroscopy (XAS). The native stream water was shown to contain mononuclear Fe-NOM complexes together with Fe(III) (hydr)oxides associated with the NOM. Addition of As(V) to this water at Fe to As ratios of 2.0-15.6 resulted in substantial changes in the Fe speciation; the Fe(III) (hydr)oxides were partly converted into FeAsO 4 (s) or a solid solution where As(V) was incorporated into Fe(III) (hydr)oxide structures. Under the same conditions no or only small effects of As(V) on the Fe-NOM complexes initially present were observed, and the concurrent existence of these complexes and free As(V) showed that a large fraction of the Fe-NOM complexes were non-reactive towards As(V). This study suggests that complexation of Fe by NOM in organic rich environments may lead to elevated free, aqueous arsenic levels as these complexes do not interact with As(V). Moreover, the formation of Fe-NOM complexes also reduce the tendency of Fe to form reactive Fe(III) (hydr)oxides particles and Fe(III)-arsenate precipitates.

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Section: Resultssupporting

confidence: 91%

Section: Chemicals and Sample Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reactivity of Fe from a natural stream water towards As(V)

Sundman

Karlsson

Persson

2015

Applied Geochemistry

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“…It has been extensively used for the speciation of actinides for two decades 19 and for transition metal speciation in the natural water compartment (see, for example, Sundman et al 20 ). It has been extensively used for the speciation of actinides for two decades 19 and for transition metal speciation in the natural water compartment (see, for example, Sundman et al 20 ).…”

Section: Introductionmentioning

confidence: 99%

XAS and TRLIF spectroscopy of uranium and neptunium in seawater

et al. 2015

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Seawater contains radionuclides at environmental levels; some are naturally present and others come from anthropogenic nuclear activity. In this report, the molecular speciation in seawater of uranium(VI) and neptunium(V) at a concentration of 5 × 10(-5) M has been investigated for the first time using a combination of two spectroscopic techniques: Time-resolved laser-induced fluorescence (TRLIF) for U and extended X-ray absorption fine structure (EXAFS) for U and Np at the LIII edge. In parallel, the theoretical speciation of uranium and neptunium in seawater at the same concentration is also discussed and compared to spectroscopic data. The uranium complex was identified as the neutral carbonato calcic complex UO2(CO3)3Ca2, which has been previously described in other natural systems. In the case of neptunium, the complex identified is mainly a carbonato complex whose exact stoichiometry is more difficult to assess. The knowledge of the actinide molecular speciation and reactivity in seawater is of fundamental interest in the particular case of uranium recovery and more generally regarding the actinide life cycle within the biosphere in the case of accidental release. This is the first report of actinide direct speciation in seawater medium that can complement inventory data.

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Improving the Measurement of Iron(III) Bioavailability in Freshwater Samples: Methods and Performance

Crespo

Reichelt‐Brushett

Smith

et al. 2022

Enviro Toxic and Chemistry

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The toxicity of iron(III) in fresh waters has been detected at concentrations above the iron solubility limit, indicating a contribution of colloidal and particulate forms of iron(III) to the toxicity response. Current water quality guideline values for iron in fresh water are based on analytical determinations of filterable or total iron. Filtration, however, can underestimate bioavailable iron by retaining some of the colloidal fraction, and total determinations overestimate bioavailable iron measurements by recovering fractions of low bioavailability from suspended solids (e.g., iron oxides and oxyhydroxides) naturally abundant in many surface waters. Consequently, there is a need for an analytical method that permits the determination of a bioavailable iron fraction, while avoiding false‐negative and false‐positive results. Ideally, a measurement technique is required that can be readily applied by commercial laboratories and field sampling personnel, and integrated into established regulatory schemes. The present study investigated the performance of pH 2 and pH 4 extractions to estimate a bioavailable iron(III) fraction in synthetic water samples containing iron phases of different reactivities. The effects of aging on fresh precipitates were also studied. The total recoverable, 0.45‐µm filtered, and pH 4 extractable fractions did not discriminate iron phases and age groups satisfactorily. Contrastingly, the pH 2 extraction showed specificity toward iron phases and aging (0.5–2‐h interval). Extraction times above 4 h and up to 16 h equally recovered >90% of the spiked iron regardless of its age. Furthermore, <1% of the well‐mineralized iron was targeted. The present study shows that a pH 2 dilute‐acid extraction is a suitable candidate method to operationally define iron fractions of higher bioavailability avoiding false‐negative and false‐positive results. Environ Toxicol Chem 2023;42:303–316. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

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An Experimental Protocol for Structural Characterization of Fe in Dilute Natural Waters

Cited by 13 publications

References 39 publications

Reactivity of Fe from a natural stream water towards As(V)

Reactivity of Fe from a natural stream water towards As(V)

XAS and TRLIF spectroscopy of uranium and neptunium in seawater

Improving the Measurement of Iron(III) Bioavailability in Freshwater Samples: Methods and Performance

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