Spatial dynamics of pH in the rhizosphere of Leersia hexandra Swartz at different chromium exposure

Na Ding; Habib Ullah; Guo Yu; Yao He; Liheng Liu; Yiruiwen Xie; Asfandyar Shahab; Hua Lin

doi:10.1016/j.ecoenv.2023.115380

Spatial dynamics of pH in the rhizosphere of Leersia hexandra Swartz at different chromium exposure

Ecotoxicol Environ Saf. 2023 Sep 15:263:115380. doi: 10.1016/j.ecoenv.2023.115380. Epub 2023 Aug 17.

Authors

Na Ding¹, Habib Ullah², Guo Yu³, Yao He⁴, Liheng Liu⁵, Yiruiwen Xie⁶, Asfandyar Shahab⁷, Hua Lin⁸

Affiliations

¹ College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China. Electronic address: 485697901@qq.com.
² Innovation Center of Yangtze River Delta, Zhejiang University, Zhejiang 311400, China. Electronic address: habib901@mail.ustc.edu.cn.
³ College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China. Electronic address: yuguo@glut.edu.cn.
⁴ College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China. Electronic address: 2544017337@qq.com.
⁵ College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China. Electronic address: deanhenry_liu01@126.com.
⁶ Department of Architecture and Environmental Engineering, Taiyuan University, Taiyuan, China. Electronic address: rivenxy1020@163.com.
⁷ College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China. Electronic address: 2017022@glut.edu.cn.
⁸ College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China. Electronic address: linhua5894@163.com.

PMID: 37597293
DOI: 10.1016/j.ecoenv.2023.115380

Abstract

The roots of hyperaccumulators can significantly alter soil pH and thus change the chromium (Cr) availability in the rhizosphere. The pH dynamics in the rhizosphere of Cr hyperaccumulator Leersia hexandra Swartz remains unknown. In this study, the spatial dynamics of pH in the rhizosphere of L. hexandra at different Cr exposure were examined using planar optode (PO). The effects of different Cr concentrations on the biomass, physiological parameters, and soil enzyme activity were investigated. The results showed that pH in the rhizosphere of L. hexandra was highly heterogeneous and followed the root shape. There were obvious soil acidification in all groups and the average pH values in the control, Cr50, and Cr100 groups decreased by 0.26, 0.27, and 0.35 pH unit, respectively. At a certain concentration (50 mg kg^-1), Cr significantly increased the plant height and biomass of L. hexandra compared to the control (p < 0.05). The concentrations of chlorophyll a, chlorophyll b, and total chlorophyll in the leaves increased with increasing Cr concentrations. The acid phosphatase, urease, and catalase activities in the rhizosphere were higher than those in the bulk soil. These results provide new insights into elucidating the hyperaccumulating mechanism of Cr and improving the phytoremediation efficiency.

Keywords: Acidification; Leersia hexandra Swartz; PH mapping; Planar optode; Rhizosphere.

MeSH terms

Chlorophyll A
Chromium / toxicity
Hydrogen-Ion Concentration
Poaceae*
Rhizosphere*
Soil

Substances

Chlorophyll A
Chromium
Soil