Identification of cadmium phytoavailability in response to cadmium transformation and changes in soil pH and electrical conductivity

Zhuoyi Yan; Wenchuan Ding; Gengxin Xie; Ming Yan; Jianbing Li; Ya Han; Xin Xiong; Chen Wang

doi:10.1016/j.chemosphere.2023.140042

Identification of cadmium phytoavailability in response to cadmium transformation and changes in soil pH and electrical conductivity

Chemosphere. 2023 Nov:342:140042. doi: 10.1016/j.chemosphere.2023.140042. Epub 2023 Sep 1.

Authors

Zhuoyi Yan¹, Wenchuan Ding², Gengxin Xie³, Ming Yan⁴, Jianbing Li⁵, Ya Han⁶, Xin Xiong⁷, Chen Wang⁸

Affiliations

¹ College of Environment and Ecology, Chongqing University, Campus B 83 Shabeijie, Shapingba, Chongqing, 400045, China; Center of Space Exploration, Ministry of Education, Chongqing University, Campus A 174 Shazhengjie, Shapingba, Chongqing, 400044, China. Electronic address: chineseyanzy91@sina.com.
² College of Environment and Ecology, Chongqing University, Campus B 83 Shabeijie, Shapingba, Chongqing, 400045, China. Electronic address: dingwenchuan@cqu.edu.cn.
³ College of Environment and Ecology, Chongqing University, Campus B 83 Shabeijie, Shapingba, Chongqing, 400045, China; Center of Space Exploration, Ministry of Education, Chongqing University, Campus A 174 Shazhengjie, Shapingba, Chongqing, 400044, China. Electronic address: xiegengxin@vip.sina.com.
⁴ College of Environmental Science and Engineering, Hunan University, Changsha, 410082, China. Electronic address: ym8188@hnu.edu.cn.
⁵ Environmental Engineering Program, University of Northern British Columbia (UNBC), Prince George, British Columbia, V2N 4Z9, Canada. Electronic address: Jianbing.Li@unbc.ca.
⁶ College of Environment and Ecology, Chongqing University, Campus B 83 Shabeijie, Shapingba, Chongqing, 400045, China. Electronic address: hy159232@163.com.
⁷ College of Environment and Ecology, Chongqing University, Campus B 83 Shabeijie, Shapingba, Chongqing, 400045, China. Electronic address: xiongxin169711@sina.com.
⁸ College of Environment and Ecology, Chongqing University, Campus B 83 Shabeijie, Shapingba, Chongqing, 400045, China. Electronic address: 202117021073@cqu.edu.cn.

PMID: 37660802
DOI: 10.1016/j.chemosphere.2023.140042

Abstract

Owing to complex changes in the soil environment, determining cadmium (Cd) phytoavailability is challenging. We devised a soil-wheat system to monitor alterations in soil pH, electrical conductivity (EC), and Cd transformation under various rates of calcium chloride and/or low-molecular-weight organic acids (LMWOAs) addition. The findings indicate that decreasing soil pH value, increasing soil EC value, and Cd transformation affect the phytoextraction of Cd. The exchangeable Cd and transformation of Cd under shifts in soil pH and EC contribute differentially to the phytoextracted Cd. The level of potentially phytoavailable Cd was identified through complete wheat cultivation in which the soil pH decreased by 0.47 unit and soil EC increased by 600-1000 μS cm^-1, resembling the concentration of 0.01 M LMWOAs extractable Cd, when transitioning from paddy to dryland soil. Based on considering the phytoextracted Cd as the phytoavailable Cd throughout a complete wheat growth term, the threshold for phytoavailable Cd in soil, ensuring the safety of wheat grain (limit: 0.1 mg kg^-1), is determined to be 2.90 μg kg^-1. Maintaining control over Cd phytoavailability in soil emerges as the key factor in ensuring the safety of wheat grain cultivation.

Keywords: Paddy-dryland rotation; Phytoavailable Cd threshold; Phytoextracted Cd; Soil EC; Soil pH; Wheat.

MeSH terms

Acids
Cadmium / analysis
Edible Grain / chemistry
Hydrogen-Ion Concentration
Oryza*
Soil
Soil Pollutants* / analysis
Triticum

Substances

Soil
Cadmium
Soil Pollutants
Acids