Solution chemistry mechanisms of exogenous silicon influencing the speciation and bioavailability of cadmium in alkaline paddy soil

Lei Guo; Aiting Chen; Cai Li; Yaojing Wang; Dan Yang; Na He; Mingda Liu

doi:10.1016/j.jhazmat.2022.129526

Solution chemistry mechanisms of exogenous silicon influencing the speciation and bioavailability of cadmium in alkaline paddy soil

J Hazard Mater. 2022 Sep 15:438:129526. doi: 10.1016/j.jhazmat.2022.129526. Epub 2022 Jul 2.

Authors

Lei Guo¹, Aiting Chen¹, Cai Li¹, Yaojing Wang², Dan Yang¹, Na He¹, Mingda Liu³

Affiliations

¹ College of Land and Environment, Shenyang Agricultural University, Shenyang, Liaoning 110866, PR China.
² College of Science, Shenyang Agricultural University, Shenyang, Liaoning 110866, PR China.
³ College of Land and Environment, Shenyang Agricultural University, Shenyang, Liaoning 110866, PR China. Electronic address: mdsausoil@syau.edu.cn.

PMID: 35999739
DOI: 10.1016/j.jhazmat.2022.129526

Abstract

The mechanism of silicon (Si) influencing cadmium (Cd) speciation and bioavailability in alkaline paddy soil solution remains unclear. Therefore, this study sought to elucidate the effect of Si on Cd by combining chemical analysis and rice pot experiments. In this work, the effects of Na₂SiO₃ alkalinity and the differences in Na⁺ were eliminated in all treatments, and the Cd speciation in soil solutions was determined in-situ using a Field-Donnan membrane technology (DMT) cell. Additionally, rice yields and the Cd content in various parts of the rice plant were studied. The results showed that Si application significantly increased rice biomass by 32% (P < 0.05) while significantly reduced the Cd content in brown rice by 52% (P < 0.01) and the free Cd²⁺ concentration in the soil solution. Further analysis of the interaction of Si and Cd using Fourier transform-infrared spectroscopy (FT-IR), Raman, and X-ray photoelectron spectroscopy (XPS) indicated that a Si-Cd complex was formed by Cd and Si-O groups. In summary, Si changed the chemical speciation of Cd in the alkaline soil solution and formed a water-soluble Si-Cd complex that the rice could not absorb, consequently reducing Cd bioavailability.

Keywords: Cadmium bioavailability; Cadmium speciation; Field-DMT cell; Rice; Silicon.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biological Availability
Cadmium / metabolism
Oryza* / metabolism
Silicon
Soil / chemistry
Soil Pollutants* / metabolism
Spectroscopy, Fourier Transform Infrared

Substances

Soil
Soil Pollutants
Cadmium
Silicon