Influence and Mechanism Study of Soil Moisture on the Stability of Arsenic-Bearing Ferrihydrite in Surface Soil Vertical Profiles

Lijuan Li, Xinyi Chen, Yan Wang, Fubin Zhang (), Xinyi Zhou and Tuo Zhang ()
Additional contact information
Lijuan Li: Institute of Agricultural Environment and Sustainable Development, Chinese Academy of Agriculture Sciences, Beijing 100081, China
Xinyi Chen: College of Environmental Science & Engineering, China West Normal University, Nanchong 637009, China
Yan Wang: College of Environmental Science & Engineering, China West Normal University, Nanchong 637009, China
Fubin Zhang: College of Environmental Science & Engineering, China West Normal University, Nanchong 637009, China
Xinyi Zhou: College of Environmental Science & Engineering, China West Normal University, Nanchong 637009, China
Tuo Zhang: School of Environmental and Life Science, Nanning Normal University, Nanning 530100, China

Agriculture, 2024, vol. 14, issue 3, 1-17

Abstract: Ferrihydrite is usually used as a remedy for arsenic (As)-contaminated soil due to its strong affinity and large specific surface area. However, its noncrystalline phase makes it unstable in long-term applications in the soil. In this study, a soil incubation experiment was designed using the diffusive gradient in thin film (DGT) technique and spectral techniques to investigate the fate of As-bearing ferrihydrite [As(V)-Fh] after long-term incubation at different soil water holding capacities (SWHCs). After As(V)-Fh (0.05 and 0.005 As/Fe molar ratio) was incubated in soil for 360 days, both DGT-derived labile As and Fe were released at 70% SWHC and 120% SWHC into the soil (at a vertical depth of 12 cm). The concentrations of DGT-As and DGT-Fe increased with incubation time and were greater at 120% SWHC. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that As(V)-Fh gradually transformed into hematite and goethite after 360 days of incubation. Goethite was mainly found in the 120% SWHC treatment after 180 days. Hematite and goethite formation rates were greater in the 120% SWHC treatment and in the bottom soil layer. Mechanistic analysis based on X-ray photoelectron spectroscopy (XPS) revealed that the variation in soil pH and the formation of Fe(II) (under flooded water conditions) are the two key factors promoting the formation of hematite (dehydrogenation and dehydration) and goethite (As(V)-Fh dissociation and reorganization). The As release mainly occurred due to the loss of adsorption sites. Thus, it is recommended that ferrihydrite be applied in paddy–dry rotations or dry-field patterns to effectively avoid the loss of As(V)-Fh in long-term-saturated soil.

Keywords: As; ferrihydrite; DGT; transformation; SWHC (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2024
References: View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/2077-0472/14/3/450/pdf (application/pdf)
https://www.mdpi.com/2077-0472/14/3/450/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jagris:v:14:y:2024:i:3:p:450-:d:1354702

Access Statistics for this article

Agriculture is currently edited by Ms. Leda Xuan

More articles in Agriculture from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().