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The effect of the ferrihydrite dissolution/transformation process on mobility of arsenic in soils: investigated by coupling a two-step sequential extraction with the diffusive gradient in the thin films (DGT) technique

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The effect of the ferrihydrite dissolution/transformation process on mobility of arsenic in soils : investigated by coupling a two-step sequential extraction with the diffusive gradient in the thin films (DGT) technique. / Zhang, T.; Zeng, X.; Zhang, H.; Lin, Q.; Su, S.; Wang, Y.; Bai, L.; Wu, C.

In: Geoderma, Vol. 352, 15.10.2019, p. 22-32.

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@article{edc0420690b1468395e3bcfabcb21a2c,
title = "The effect of the ferrihydrite dissolution/transformation process on mobility of arsenic in soils: investigated by coupling a two-step sequential extraction with the diffusive gradient in the thin films (DGT) technique",
abstract = "Ferrihydrite has been prevalently used in soil remediation as an effective amendment for in situ immobilization of arsenic (As). However, its poorly crystalline structure is unstable and can pose the risk of re-releasing As into soil. In this study, sequential extraction was coupled with a newly-established method, chelex-metsorb diffusive gradient in thin films (DGT), to study the ferrihydrite transformation/dissolution process and its effect on the mobility of arsenic in soil. Experiments in this work found that high soil moisture (70% SWHC) with a low soil redox potential (Eh) can significantly increase the rate of the ferrihydrite transformation/dissolution process compared to 30% SWHC. Soils with low pH and high available iron (Fe) content may also accelerate ferrihydrite transformation/dissolution, while soils with high clay fraction and high soil total organic matter (STOM) may inhibit the process. The amount of arsenic adsorption can also affect ferrihydrite transformation, even exceeding the effect of soil pH and dissolved Fe. Arsenic release was clearly observed in all three soils across all treatments, and it was also affected by changes in soil redox potential. More arsenic was released at high soil moisture (70% SWHC) roughly 7–15 d after the release of Fe. In addition, a partial arsenic fraction was transformed, along with ferrihydrite, from a combined As (F1–As) amorphous phase to combined As (F2–As) well-crystallized phase. These results suggested that ferrihydrite transformation/dissolution can affect the mobility of arsenic and that this phenomenon is more extreme at higher soil moisture levels. ",
keywords = "As, DGT, Ferrihydrite, pH, Soils, Transformation/dissolution, Arsenic, Extraction, Positive ions, Redox reactions, Soil conservation, Soil pollution, Thin films, Crystalline structure, Diffusive gradients, Ferrihydrites, Sequential extraction, Situ immobilization, Soil redox potential, Total organic matter, Soil moisture",
author = "T. Zhang and X. Zeng and H. Zhang and Q. Lin and S. Su and Y. Wang and L. Bai and C. Wu",
year = "2019",
month = oct,
day = "15",
doi = "10.1016/j.geoderma.2019.05.042",
language = "English",
volume = "352",
pages = "22--32",
journal = "Geoderma",
issn = "0016-7061",
publisher = "Elsevier Science B.V.",

}

RIS

TY - JOUR

T1 - The effect of the ferrihydrite dissolution/transformation process on mobility of arsenic in soils

T2 - investigated by coupling a two-step sequential extraction with the diffusive gradient in the thin films (DGT) technique

AU - Zhang, T.

AU - Zeng, X.

AU - Zhang, H.

AU - Lin, Q.

AU - Su, S.

AU - Wang, Y.

AU - Bai, L.

AU - Wu, C.

PY - 2019/10/15

Y1 - 2019/10/15

N2 - Ferrihydrite has been prevalently used in soil remediation as an effective amendment for in situ immobilization of arsenic (As). However, its poorly crystalline structure is unstable and can pose the risk of re-releasing As into soil. In this study, sequential extraction was coupled with a newly-established method, chelex-metsorb diffusive gradient in thin films (DGT), to study the ferrihydrite transformation/dissolution process and its effect on the mobility of arsenic in soil. Experiments in this work found that high soil moisture (70% SWHC) with a low soil redox potential (Eh) can significantly increase the rate of the ferrihydrite transformation/dissolution process compared to 30% SWHC. Soils with low pH and high available iron (Fe) content may also accelerate ferrihydrite transformation/dissolution, while soils with high clay fraction and high soil total organic matter (STOM) may inhibit the process. The amount of arsenic adsorption can also affect ferrihydrite transformation, even exceeding the effect of soil pH and dissolved Fe. Arsenic release was clearly observed in all three soils across all treatments, and it was also affected by changes in soil redox potential. More arsenic was released at high soil moisture (70% SWHC) roughly 7–15 d after the release of Fe. In addition, a partial arsenic fraction was transformed, along with ferrihydrite, from a combined As (F1–As) amorphous phase to combined As (F2–As) well-crystallized phase. These results suggested that ferrihydrite transformation/dissolution can affect the mobility of arsenic and that this phenomenon is more extreme at higher soil moisture levels.

AB - Ferrihydrite has been prevalently used in soil remediation as an effective amendment for in situ immobilization of arsenic (As). However, its poorly crystalline structure is unstable and can pose the risk of re-releasing As into soil. In this study, sequential extraction was coupled with a newly-established method, chelex-metsorb diffusive gradient in thin films (DGT), to study the ferrihydrite transformation/dissolution process and its effect on the mobility of arsenic in soil. Experiments in this work found that high soil moisture (70% SWHC) with a low soil redox potential (Eh) can significantly increase the rate of the ferrihydrite transformation/dissolution process compared to 30% SWHC. Soils with low pH and high available iron (Fe) content may also accelerate ferrihydrite transformation/dissolution, while soils with high clay fraction and high soil total organic matter (STOM) may inhibit the process. The amount of arsenic adsorption can also affect ferrihydrite transformation, even exceeding the effect of soil pH and dissolved Fe. Arsenic release was clearly observed in all three soils across all treatments, and it was also affected by changes in soil redox potential. More arsenic was released at high soil moisture (70% SWHC) roughly 7–15 d after the release of Fe. In addition, a partial arsenic fraction was transformed, along with ferrihydrite, from a combined As (F1–As) amorphous phase to combined As (F2–As) well-crystallized phase. These results suggested that ferrihydrite transformation/dissolution can affect the mobility of arsenic and that this phenomenon is more extreme at higher soil moisture levels.

KW - As

KW - DGT

KW - Ferrihydrite

KW - pH

KW - Soils

KW - Transformation/dissolution

KW - Arsenic

KW - Extraction

KW - Positive ions

KW - Redox reactions

KW - Soil conservation

KW - Soil pollution

KW - Thin films

KW - Crystalline structure

KW - Diffusive gradients

KW - Ferrihydrites

KW - Sequential extraction

KW - Situ immobilization

KW - Soil redox potential

KW - Total organic matter

KW - Soil moisture

U2 - 10.1016/j.geoderma.2019.05.042

DO - 10.1016/j.geoderma.2019.05.042

M3 - Journal article

VL - 352

SP - 22

EP - 32

JO - Geoderma

JF - Geoderma

SN - 0016-7061

ER -