Issue 5, 2023

Speciation of Zn and Cd in sierozem soil, northwest China: bulk EXAFS and micro synchrotron X-ray fluorescence

Abstract

Previous research studies have confirmed that Zn and Cd are the most predominant heavy metals in the Baiyin district, Gansu province, China. Furthermore, the speciation of Zn and Cd is a key factor in controlling the mobility, bioavailability, and toxicity of metals in Zn/Cd co-contaminated soil. In this study, the speciation of Zn and Cd in different types of agricultural soils including the Yellow River irrigated soil (s3) and sewage irrigated soil (s1 and s2) was investigated and compared by a combination of sequential extraction, bulk X-ray absorption fine structure (XAFS), and micro-X-ray fluorescence (μ-XRF) techniques. The results of the speciation quantified by XAFS were in general agreement with those obtained by sequential extraction, and the combination of both approaches allowed a reliable description of Zn/Cd speciation in soil. The speciation of Zn in the s1 soil exposed around the smelter was similar to speciation of Zn in the sewage irrigated s2 soil. In both soils, Zn was predominantly present as Zn–Al LDH (31–36%), Zn adsorbed on calcite (37–47%), and primary minerals (14–18% sphalerite and 9% franklinite). In contrast, the proportions of organic Zn (23%) and Zn–Al LDH (53%) were significantly higher in the Yellow River irrigated s3 soil, while that of Zn-calcite (24%) was lower. This indicated that Zn in s3 was less mobile and bioavailable than that in s1 and s2 soils. The content of bioavailable Zn in s3 was much lower than the background value and Zn did not pose a threat to the Yellow River irrigated soil. In addition, Cd was strongly correlated with Zn content and exhibited a simpler speciation. Cd adsorbed on illite and calcite was found as the major species in both soil types, posing higher migration and toxicity to the environment. Our study reported the speciation and correlation of Zn/Cd in sierozem soil for the first time and provided a significant theoretical basis for remediation actions to minimize Zn/Cd risks.

Graphical abstract: Speciation of Zn and Cd in sierozem soil, northwest China: bulk EXAFS and micro synchrotron X-ray fluorescence

Supplementary files

Article information

Article type
Paper
Submitted
07 Feb 2023
Accepted
08 Mar 2023
First published
13 Apr 2023

Environ. Sci.: Processes Impacts, 2023,25, 954-963

Speciation of Zn and Cd in sierozem soil, northwest China: bulk EXAFS and micro synchrotron X-ray fluorescence

X. Zhao, Y. Takahashi, W. Wu, C. Liu and Q. Fan, Environ. Sci.: Processes Impacts, 2023, 25, 954 DOI: 10.1039/D3EM00052D

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements