The impact of ionic strength on the proton reactivity of clay minerals

Hao, Weiduo; Flynn, Shannon L.; Kashiwabara, Teruhiko; Alam, Sabiha; Bandara, Sasiri; Swaren, Logan; Robbins, Leslie J.; Alessi, Daniel S.; Konhauser, Kurt O.

doi:10.1016/j.chemgeo.2019.119294

Cited by 34 publications

(31 citation statements)

References 54 publications

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“…2 ). However, the surface charge of kaolinite is pH-dependent 48 , 49 . Surface complexation modeling based on acid-base titrations of kaolinite shows that kaolinite surface functional groups are highly protonated at pH < 4.7, lending the clay a net positive charge (supplementary note 4), which can electrostatically attract negatively charged P species (dominantly H 2 PO 4 − at pH 2–7).…”

Section: Resultsmentioning

confidence: 99%

The kaolinite shuttle links the Great Oxidation and Lomagundi events

Hao

Mänd

et al. 2021

Nat Commun

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The ~2.22–2.06 Ga Lomagundi Event was the longest positive carbon isotope excursion in Earth’s history and is commonly interpreted to reflect perturbations in continental weathering and the phosphorous cycle. Previous models have focused on mechanisms of increasing phosphorous solubilization during weathering without focusing on transport to the oceans and its dispersion in seawater. Building from new experimental results, here we report kaolinite readily absorbs phosphorous under acidic freshwater conditions, but quantitatively releases phosphorous under seawater conditions where it becomes bioavailable to phytoplankton. The strong likelihood of high weathering intensities and associated high kaolinite content in post-Great-Oxidation-Event paleosols suggests there would have been enhanced phosphorus shuttling from the continents into marine environments. A kaolinite phosphorous shuttle introduces the potential for nonlinearity in the fluxes of phosphorous to the oceans with increases in chemical weathering intensity.

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Section: Resultsmentioning

confidence: 99%

The kaolinite shuttle links the Great Oxidation and Lomagundi events

Hao

Mänd

et al. 2021

Nat Commun

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“…Surface complexation modeling (SCM) was used to model the protonation‐deprotonation behavior of functional groups on the surfaces of minerals in mud samples as a function of solution pH. Since the mud samples are mostly composed of clay minerals, we applied the same model for protonation and deprotonation surface reactions as used in previous clay studies (Barbier et al., 2000; Hao et al., 2018; Hao, Flynn, et al., 2019; Ikhsan et al., 2005; Lackovic et al., 2003; Peacock & Sherman, 2005). The following surface complexation reactions and corresponding mass action equations were used:

\equiv L N a + H^{+} \leftrightarrow \equiv L H + N a^{+}

K = \frac{[\equiv LH] • α_{{Na}^{+}}}{[\equiv LNa] • α_{H^{+}}}

\equiv X O H \leftrightarrow H^{+} + \equiv X O^{-}

{normalK}_{a -} = \frac{[\equiv {XO}^{-}] • α_{H^{+}}}{[\equiv XOH]}

\equiv X O H + H^{+} \leftrightarrow \equiv X O H_{2}^{+}

{normalK}_{a +} = \frac{[\equiv {XOH}_{2}^{+}]}{[\equiv XOH] • α_{H^{+}}}

…”

Section: Discussionmentioning

confidence: 99%

Trace Elemental Partitioning on Clays Derived From Hydrothermal Muds of the El Tatio Geyser Field, Chile

et al. 2021

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“…Cadmium was chosen based on its wide use in biosorption studies and it is representative of a wide range of trace metals (e.g. Liu et al, 2015;Hao et al, 2019Hao et al, , 2020. Initially 100 ml of 0.56 M NaCl was added to a 150 ml glass beaker.…”

Section: Cadmium Adsorption Experimentsmentioning

confidence: 99%

“…Both D. cuprea and C. major are characterized by approximately 50% of Cd adsorption at pH 9, whereas A. marina faecal material is characterized by approximately 25% Cd adsorption at this pH. Surface complexation models (SCMs) provide a more versatile solution over traditional adsorption isotherm approaches because they account for variations in system pH and ionic strength that can occur in an estuarine environment and impact the extent of metal adsorption (Fein, 2017;Alam et al, 2018;Alessi et al, 2019). Using the pK a values and site concentrations determined in the protonation models, a nonelectrostatic SCM approach was applied to the Cd adsorption data to calculate Cd adsorption equilibrium constants, invoking the following two reactions (except for A. marina which only invokes one adsorption site):…”

Section: Cadmium Adsorption Experimentsmentioning

confidence: 99%

The influence of invertebrate faecal material on compositional heterogeneity, diagenesis and trace metal distribution in the Ogeechee River estuary, Georgia, USA

et al. 2020

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Bioturbating organisms contribute significantly to elemental cycling in sediments through burrowing, grazing, organic matter and altering porewater chemical conditions. In the process, organisms are known to produce copious amounts of faecal material at high rates, sometimes in excess of 1 000 000 kg day−1 in a 1 km2 area. Material from three organisms (Arenicola marina, Callichirus major and Diopatra cuprea) was collected from two locations, Raccoon Key and Steamboat Pass, in the Ogeechee River estuary, Georgia, USA, to explore how faecal production affects organic carbon cycling and clay mineralogies. The individual organisms’ feeding strategies played a strong role in the extent to which they concentrate organic matter and lead to the formation of clay minerals. The faecal material of filter feeding Diopatra cuprea and selective deposit feeding Callichirus major contains up 45.8% and 47.3% kaolinite, respectively, while kaolinite is below detection limits in the surrounding matrix. By contrast, the non‐selective deposit‐feeder Arenicola marina does not appear to form or concentrate clay minerals. Callichirus major increases organic carbon contents at Raccoon Key by 68‐fold and Diopatra cuprea increases total organic carbon (w/w%) by 119‐fold and 32‐fold at Raccoon Key and Steamboat Pass, respectively. Arenicola marina, in contrast, does not noticeably concentrate organic matter in its faecal material, most likely as a consequence of non‐selective deposit‐feeding. Potentiometric titration data was used to explore surface reactivity and metal sorption. Diopatra cuprea and Callichirus major faecal material has strong metal binding affinities relative to the surrounding matrix, thereby increasing the potential for trace metals to be sequestered into the sedimentary record. The widespread occurrence of invertebrate faecal material enriched in clay minerals and organic matter likely has a significant influence on organic matter, grain size and trace metal distribution in estuarine sediments.

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The impact of ionic strength on the proton reactivity of clay minerals

Cited by 34 publications

References 54 publications

The kaolinite shuttle links the Great Oxidation and Lomagundi events

The kaolinite shuttle links the Great Oxidation and Lomagundi events

Trace Elemental Partitioning on Clays Derived From Hydrothermal Muds of the El Tatio Geyser Field, Chile

The influence of invertebrate faecal material on compositional heterogeneity, diagenesis and trace metal distribution in the Ogeechee River estuary, Georgia, USA

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