Extreme iron isotope fractionation between colloids and particles of boreal and temperate organic-rich waters

Ilina, Svetlana; Poitrasson, Franck; Lapitskiy, S. A.; Alekhin, Yuriy V.; Viers, Jérôme; Pokrovsky, Oleg S.

doi:10.1016/j.gca.2012.10.023

Cited by 107 publications

(120 citation statements)

References 84 publications

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“…56 Fe values Fe measured in Arctic rivers to date (À1.7‰) occurs in the <0.1 lm to <1 kD size fraction of small organic-rich arctic rivers (Ilina et al, 2013;Escoube et al, 2015). Glacial ouflows are not organic rich compared with riverine systems, with dissolved organic carbon concentrations typically on the order of 0.32 mg L À1 (Bhatia et al, 2013b).…”

Section: Controls On the Fe Isotopic Composition Of Dissolved Fe In Smentioning

confidence: 96%

“…Fantle and DePaolo, 2004;Bergquist and Boyle, 2006;Ilina et al, 2013;Chen et al, 2014;Escoube et al, 2015). In addition, it is expected that the geochemistry of glacial streams is impacted by subglacial weathering processes such as icerock grinding, water-rock interaction, and microbial activity that have been documented to fractionate Fe isotopically (e.g.…”

mentioning

confidence: 99%

“…For example, isotopic effects as large as 4‰ have been associated with organic-Fe complexation (e.g. Dideriksen et al, 2008;Ilina et al, 2013), abiotic precipitation of Fe(III) (e.g. Bullen et al, 2001;Balci et al, 2006), and silicate weathering (Kiczka et al, 2011).…”

mentioning

confidence: 99%

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The iron isotopic composition of subglacial streams draining the Greenland ice sheet

Stevenson

Fantle

Das

et al. 2017

Geochimica et Cosmochimica Acta

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Section: Controls On the Fe Isotopic Composition Of Dissolved Fe In Smentioning

confidence: 96%

mentioning

confidence: 99%

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The iron isotopic composition of subglacial streams draining the Greenland ice sheet

Stevenson

Fantle

Das

et al. 2017

Geochimica et Cosmochimica Acta

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“…The colloidal fraction of the A4 river locality (10 kD -0.2 mm) is heavier (À0.14 ± 0.07‰, 2SD) than the corresponding dissolved fraction (<0.2 mm; À0.46 ± 0.07‰, 2SD). Based on an isotope mass balance calculation where 26% of Fe has been measured in the colloidal fraction ( (Ingri et al, 2006;Ilina et al, 2013;Akerman et al, 2014;Escoube et al, 2015;Mulholland et al, 2015;Fig. 5a) relative to the dissolved fraction of global rivers (e.g., Bergquist and Boyle, 2006).…”

Section: Implications For the Fe Export To Riversmentioning

confidence: 99%

Iron and silicon isotope behaviour accompanying weathering in Icelandic soils, and the implications for iron export from peatlands

Opfergelt

Williams

Cornélis

et al. 2017

Geochimica et Cosmochimica Acta

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Incipient warming of peatlands at high latitudes is expected to modify soil drainage and hence the redox conditions, which has implications for Fe export from soils. This study uses Fe isotopes to assess the processes controlling Fe export in a range of Icelandic soils including peat soils derived from the same parent basalt, where Fe isotope variations principally reflect differences in weathering and drainage. In poorly weathered, well-drained soils (non-peat soils), the limited Fe isotope fractionation in soil solutions relative to the bulk soil (D 57 Fe solution-soil = À0.11 ± 0.12‰) is attributed to proton-promoted mineral dissolution. In the more weathered poorly drained soils (peat soils), the soil solutions are usually lighter than the bulk soil (D 57 Fe solution-soil = À0.41 ± 0.32‰), which indicates that Fe has been mobilised by reductive mineral dissolution and/or ligand-controlled dissolution. The results highlight the presence of Fe-organic complexes in solution in anoxic conditions. An additional constraint on soil weathering is provided by Si isotopes. The Si isotope composition of the soil solutions relative to the soil (D 30 Si solution-soil = 0.92 ± 0.26‰) generally reflects the incorporation of light Si isotopes in secondary aluminosilicates. Under anoxic conditions in peat soils, the largest Si isotope fractionation in soil solutions relative to the bulk soil is observed (D 30 Si solution-soil = 1.63 ± 0.40‰) and attributed to the cumulative contribution of secondary clay minerals and amorphous silica precipitation. Si supersaturation in solution with respect to amorphous silica is reached upon freezing when Al availability to form aluminosilicates is limited by the affinity of Al for metal-organic complexes. Therefore, the precipitation of amorphous silica in peat soils indirectly supports the formation of metal-organic complexes in poorly drained soils. These observations highlight that in a scenario of decreasing soil drainage with warming high latitude peatlands, Fe export from soils as Fe-organic complexes will increase, which in turn has implications for Fe transport in rivers, and ultimately the delivery of Fe to the oceans.

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“…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%

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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Extreme iron isotope fractionation between colloids and particles of boreal and temperate organic-rich waters

Cited by 107 publications

References 84 publications

The iron isotopic composition of subglacial streams draining the Greenland ice sheet

The iron isotopic composition of subglacial streams draining the Greenland ice sheet

Iron and silicon isotope behaviour accompanying weathering in Icelandic soils, and the implications for iron export from peatlands

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

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