Effects of Different Particle Sizes of Hydroxyapatite on the Distribution and Migration of Trace Elements (Copper and Cadmium) in a Smelter-Impacted Soil.

Lei Xu,Jing Zhou,Mingfei Ji,Xiangyu Xing,Ding Li,Jianbiao Peng,Hongbiao Cui,Zhenqiu Zhu

doi:10.1155/2021/2412646

Abstract

To study the remediation effect of hydroxyapatite with different particle sizes, a field in situ experiment was carried out by adding conventional hydroxyapatite (0.25 mm) and microhydroxyapatite (3 μm) and nanohydroxyapatite (40 nm) to the contaminated soil and planting Elsholtzia splendens. The distribution and migration of copper (Cu) and cadmium (Cd) in soil were investigated after 4 years. The results show that the application of three different particle sizes of hydroxyapatite significantly raise the soil pH, total phosphorus, and soil organic carbon. Moreover, the addition of hydroxyapatite can reduce the EXC fraction of Cu and Cd by 73.7%–80.1% and 20.8%–35.2%, respectively. In addition, the concentrations of Cu and Cd in >2 mm, 0.25–2 mm, 0.053–0.25 mm, and <0.053 mm aggregate are significantly increased. This improvement indicates that there are risks which may cause the increasing of total Cu and Cd in the soil where the pollution sources still exist. Furthermore, the content of soil colloid is significantly increased, and the colloidal Cu and Cd distribution percentage have been significantly increased by 49.9%–120% and 30.3%–181%. This result illustrates that the application of hydroxyapatite may greatly increase the possibility of colloid and dust migration of Cu and Cd.

Highlights

Lei Xu,1,2 Xiangyu Xing,3 Zhenqiu Zhu,4 Hongbiao Cui,5 Jianbiao Peng,6 Ding Li,1 Mingfei Ji,2 and Jing Zhou4
To study the remediation effect of hydroxyapatite with different particle sizes, a field in situ experiment was carried out by adding conventional hydroxyapatite (0.25 mm) and microhydroxyapatite (3 μm) and nanohydroxyapatite (40 nm) to the contaminated soil and planting Elsholtzia splendens. e distribution and migration of copper (Cu) and cadmium (Cd) in soil were investigated after 4 years. e results show that the application of three different particle sizes of hydroxyapatite significantly raise the soil pH, total phosphorus, and soil organic carbon
Farmers had used water containing heavy metals to irrigate for a long time, which led to heavy metal contamination in soil and Cd concentrations in rice exceeding the national food health standards (GB 15201-94). e soil texture is sandy loam, and the pH is 4.63. e contents of soil organic carbon, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus, and available potassium are 16.3 g·kg−1, 1.33 g·kg−1, 0.261 g·kg−1, 2.38 g·kg−1, 67.1 mg·kg−1, 186 mg·kg−1, and 54.8 mg·kg−1, respectively

Summary

Introduction

Lei Xu ,1,2 Xiangyu Xing, Zhenqiu Zhu, Hongbiao Cui, Jianbiao Peng, Ding Li, Mingfei Ji, and Jing Zhou. A large number of studies have shown that phosphoruscontaining materials (e.g., apatite, potassium dihydrogen phosphate, superphosphate, and hydroxyapatite) can effectively reduce the activities of heavy metals, such as Pb, Cd, and Cu in soil and wastewater [7]. Dong’s research results suggested that micro-nano hydroxyapatite whose particle size between microhydroxyapatite and nanohydroxyapatite was more helpful to reduce the availability of Cu and Cd in contaminated soil than microhydroxyapatite and nanohydroxyapatite [14]. Most of the studies about hydroxyapatite only focus on its effect on the heavy metal activity and bioavailability, but there are few researches paying attention to its potential effect on the distribution and migration of heavy metals in soil

Methods

Results

Conclusion