Aggregation of nanoscale iron oxyhydroxides and corresponding effects on metal uptake, retention, and speciation: II. Temperature and time

Stegemeier, John P.; Reinsch, Brian C.; Lentini, C.J.; Dale, James G.; Kim, C.S.

doi:10.1016/j.gca.2014.08.031

Cited by 20 publications

(13 citation statements)

References 64 publications

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“…The unique features of subglacial weathering environments provide an explanation for the predominance of these colloidal/ nanoparticulate TE phases. The low temperatures (∼0°C) may aid in slowing the aggregation and aging of nanoparticles into denser, larger-size fractions >0.45 μm in size, with smaller aggregates having a greater adsorption capacity due to their extremely high surface area to volume ratios (54). Additionally, aggregation under higher pH conditions (mean pH was >8, up to 9.6) (SI Appendix, Table S1) has been found to generate less ordered porous aggregates with high sorption properties (55).…”

Section: Resultsmentioning

confidence: 99%

Enhanced trace element mobilization by Earth’s ice sheets

Hawkings

Skidmore

Wadham

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Trace elements sustain biological productivity, yet the significance of trace element mobilization and export in subglacial runoff from ice sheets is poorly constrained at present. Here, we present size-fractionated (0.02, 0.22, and 0.45 µm) concentrations of trace elements in subglacial waters from the Greenland Ice Sheet (GrIS) and the Antarctic Ice Sheet (AIS). Concentrations of immobile trace elements (e.g., Al, Fe, Ti) far exceed global riverine and open ocean mean values and highlight the importance of subglacial aluminosilicate mineral weathering and lack of retention of these species in sediments. Concentrations are higher from the AIS than the GrIS, highlighting the geochemical consequences of prolonged water residence times and hydrological isolation that characterize the former. The enrichment of trace elements (e.g., Co, Fe, Mn, and Zn) in subglacial meltwaters compared with seawater and typical riverine systems, together with the likely sensitivity to future ice sheet melting, suggests that their export in glacial runoff is likely to be important for biological productivity. For example, our dissolved Fe concentration (20,900 nM) and associated flux values (1.4 Gmol y−1) from AIS to the Fe-deplete Southern Ocean exceed most previous estimates by an order of magnitude. The ultimate fate of these micronutrients will depend on the reactivity of the dominant colloidal size fraction (likely controlled by nanoparticulate Al and Fe oxyhydroxide minerals) and estuarine processing. We contend that ice sheets create highly geochemically reactive particulates in subglacial environments, which play a key role in trace elemental cycles, with potentially important consequences for global carbon cycling.

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Section: Resultsmentioning

confidence: 99%

Enhanced trace element mobilization by Earth’s ice sheets

Hawkings

Skidmore

Wadham

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…Stegemeier et al . 49 , 50 pointed out that the factors that enhance iron oxyhydroxides nanoparticle aggregation generally follow the order of ionic strength ≈ pH < aging < freezing < drying. Accordingly, the interstitial water and pore space between aggregated particles are decreased by these factors and result in greater compaction of the aggregates and smaller specific surface areas in the same order.…”

Section: Resultsmentioning

confidence: 99%

Roles of different types of oxalate surface complexes in dissolution process of ferrihydrite aggregates

Koopal

Tan

2018

Sci Rep

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The dissolution of ferrihydrite induced by low molar mass (LMM) organics is an important process that provides bioavailable iron for organisms. Here, ATR-FTIR analysis was combined with characterization of ferrihydrite nanoparticles and kinetic modeling to investigate the roles of different oxalate surface complex species in the dissolution of ferrihydrite aggregates. ATR-FTIR results revealed that at least four different species were present at or near the ferrihydrite surface in the process of ferrihydrite aggregate dissolution. At a relatively low addition of oxalate (oxalate/Fe < 0.1), oxalate was dominantly present as binuclear bidentate surface complexes and aqueous species. The binuclear bidentate complexes mainly caused electrostatic repulsion between particles, resulting in the disaggregation of large ferrihydrite aggregates into colloidal particles with hydrodynamic diameters of 116–174 nm. Kinetic modeling showed that these colloidal particles were stable at the oxalate/Fe ratio of 0.1. With increasing addition of oxalate (oxalate/Fe ≥ 0.1), mononuclear bidentate oxalate complexes and hydrogen-bonded surface complex replaced the binuclear bidentate complexes and aqueous species. The aggregates or larger colloidal particles were further disaggregated into smaller colloidal particles with hydrodynamic diameters of 35–64 nm. Additionally, the mononuclear bidentate oxalate complexes promoted the dissolution of ferrihydrite colloids into dissolved Fe.

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“…The even adsorption of heavy metals on gellike ferrihydrite may be because of the open and loosely aggregated structure, which provided larger surface area, more accessible binding sites, and higher sticking efficiency (Wang et al, 2013, 2016, Wang et al, 2015a). However, freeze‐drying resulted in a much denser structure with reduced surface area and less accessible metal binding sites (Dale et al, 2015; Scheinost et al, 2001; Stegemeier et al, 2015). As a result, metal could only adsorb on certain accessible binding sites but not a great number of other hidden binding sites of dense ferrihydrite in the short term.…”

Section: Resultsmentioning

confidence: 99%

“…However, the impact of ferrihydrite morphologies on the reactivity of ferrihydrite with heavy metals and underlying mechanisms remain unclear. The changing of aggregation state and morphology of ferrihydrite was found to have large effects on metal uptake, retention, and speciation (Dale et al, 2015; Gilbert et al, 2009; Stegemeier et al, 2015; Vindedahl et al, 2016). The gellike ferrihydrite aggregate forming through fast precipitation represents the newly formed ferrihydrite during Fe cycling in soil, while the denser ferrihydrite aggregate occurs through slow redox precipitation or through seasonal drying of ferrihydrite gel in redoxomorphic soils, both of which had significant impact on metal adsorption behavior (Scheinost et al, 2001).…”

mentioning

confidence: 99%

“…The gellike ferrihydrite aggregate forming through fast precipitation represents the newly formed ferrihydrite during Fe cycling in soil, while the denser ferrihydrite aggregate occurs through slow redox precipitation or through seasonal drying of ferrihydrite gel in redoxomorphic soils, both of which had significant impact on metal adsorption behavior (Scheinost et al, 2001). Previous studies found that increasing ferrihydrite aggregation led to the decreasing percentage of metal adsorption (Dale et al, 2015), and the transition from low to high aggregation states reduced pore space between aggregated particles and resulted in the more condensed aggregate and less reactive surface area (Dale et al, 2015; Gilbert et al, 2009; Hofmann et al, 2004; Scheinost et al, 2001; Stegemeier et al, 2015). Therefore, the changes of morphology and reactive surface areas may have significant implications on the fate of heavy metals in soil environments.…”

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confidence: 99%

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Pb(II) and Cu(II) Adsorption and Desorption Kinetics on Ferrihydrite with Different Morphologies

Tian

Yao

et al. 2018

Soil Science Soc of Amer J

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Gellike and dense ferrihydrite had different structures and Pb/Cu distributions. Ferrihydrite morphology and solution chemistry affected sorption and desorption kinetics. The kinetics model successfully described the stirred‐flow kinetic data of Pb and Cu. Different binding sites controlled adsorption and desorption kinetics differently. Understanding the effect of ferrihydrite morphology on the kinetic reactions of metals with ferrihydrite is essential for predicting the dynamic behavior of metals in soil. In this study, kinetics of Pb(II) and Cu(II) adsorption and desorption on two types of ferrihydrite, the freshly precipitated gellike ferrihydrite and freeze‐dried dense ferrihydrite representing two typical morphologies under extreme soil conditions, were studied. The high‐resolution transmission electron microscopy (TEM) images revealed that the gellike ferrihydrite loosely aggregated with open structure, while the dense ferrihydrite compactly aggregated with more consolidated and thicker structure. The energy dispersive spectroscopy (EDS), at the nanometer scale, showed that Pb(II) and Cu(II) distributed evenly on gellike ferrihydrite but localized on dense ferrihydrite after adsorption. The stirred‐flow kinetic experiments showed that higher pH and higher influent metal concentrations increased metal adsorption for both types of ferrihydrite. The dense ferrihydrite adsorbed slower and much less metals than gellike ferrihydrite because of less reactive sites. The desorption of heavy metals from ferrihydrite was affected by combined factors of the ferrihydrite morphology, adsorbed metal concentrations, pH, and metal re‐adsorption rates. The mechanic kinetics model based on the CD‐MUSIC model successfully described the adsorption and desorption kinetics of Pb(II) and Cu(II) on both gellike and dense ferrihydrite under various chemistry conditions. Our model provided quantitative tools for considering the effects of ferrihydrite morphology and heterogeneous binding sites under varying solution chemistry conditions when predicting the dynamic behavior of Pb(II) and Cu(II) in soil environment.

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Aggregation of nanoscale iron oxyhydroxides and corresponding effects on metal uptake, retention, and speciation: II. Temperature and time

Cited by 20 publications

References 64 publications

Enhanced trace element mobilization by Earth’s ice sheets

Enhanced trace element mobilization by Earth’s ice sheets

Roles of different types of oxalate surface complexes in dissolution process of ferrihydrite aggregates

Pb(II) and Cu(II) Adsorption and Desorption Kinetics on Ferrihydrite with Different Morphologies

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