Insight into the mechanism of phosphate and cadmium co-transport in natural soils

Xiaoli Wu; Bin Gao; Xueyan Lyu; Xiankui Zeng; Jichun Wu; Yuanyuan Sun

doi:10.1016/j.jhazmat.2022.129095

Insight into the mechanism of phosphate and cadmium co-transport in natural soils

J Hazard Mater. 2022 Aug 5:435:129095. doi: 10.1016/j.jhazmat.2022.129095. Epub 2022 May 7.

Authors

Xiaoli Wu¹, Bin Gao², Xueyan Lyu³, Xiankui Zeng¹, Jichun Wu¹, Yuanyuan Sun⁴

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Hydrosciences Department, Nanjing University, Nanjing 210023, China.
² Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, USA.
³ School of Hydrology and Water Resources, Nanjing University of Information Science and Technology, Nanjing 210044, China.
⁴ State Key Laboratory of Pollution Control and Resource Reuse, Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Hydrosciences Department, Nanjing University, Nanjing 210023, China. Electronic address: sunyy@nju.edu.cn.

PMID: 35650735
DOI: 10.1016/j.jhazmat.2022.129095

Abstract

Phosphate is ubiquitous in the environment and can affect the transport of heavy metals in the subsurface systems. In this study, column experiments were conducted to systematically evaluate the effects of phosphate on the transport of Cd in natural soils (RS, BS) under different ionic strength (IS) conditions. The presence of phosphate significantly retarded the transport of Cd in the soils. The extent of retardation was closely associated with phosphate concentrations, IS and soil properties. Increasing phosphate adsorption induced more negative surface charges on soils, thereby contributing to greater retention of Cd through electrostatic attraction. In contrast, higher IS not only promoted mobility of Cd, but also reduced the retardation effect of phosphate on Cd transport in soils. Moreover, higher Fe/Al oxides contents in RS exhibited a more pronounced effect of phosphate on Cd retardation. Our results indicated that electrostatic interaction was the predominant mechanism controlling co-transport of Cd with phosphate, but no ternary surface complexes was observed in the Cd L_III-edge XANES spectra. Our findings highlight the critical role of phosphate in retarding Cd transport in natural soils, which should be considered in assessing environmental risks of heavy metals in the subsurface.

Keywords: Cd; Phosphate; Soil properties; Transport; XANES.

Publication types

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

MeSH terms

Cadmium / analysis
Metals, Heavy* / analysis
Phosphates
Soil
Soil Pollutants* / analysis

Substances

Metals, Heavy
Phosphates
Soil
Soil Pollutants
Cadmium