Abstract
It was believed that when hydroxyapatite (HAP) was used to remediate heavy metal-contaminated soils, its effectiveness seemed likely to be affected by its particle size. In this study, a pot trial was conducted to evaluate the efficiency of two particle sizes of HAP: nanometer particle size of HAP (nHAP) and micrometer particle size of HAP (mHAP) induced metal immobilization in soils. Both mHAP and nHAP were assessed for their ability to reduce lead (Pb), zinc (Zn), copper (Cu), and chromium (Cr) bioavailability in an artificially metal-contaminated soil. The pakchoi (Brassica chinensisL.) uptake and soil sequential extraction method were used to determine the immobilization and bioavailability of Pb, Zn, Cu, and Cr. The results indicated that both mHAP and nHAP had significant effect on reducing the uptake of Pb, Zn, Cu, and Cr by pakchoi. Furthermore, both mHAP and nHAP were efficient in covering Pb, Zn, Cu, and Cr from nonresidual into residual forms. However, mHAP was superior to nHAP in immobilization of Pb, Zn, Cu, and Cr in metal-contaminated soil and reducing the Pb, Zn, Cu, and Cr utilized by pakchoi. The results suggested that mHAP had the better effect on remediation multiple metal-contaminated soils than nHAP and was more suitable for applying inin situremediation technology.
Highlights
Heavy metal pollution in the soil has become a serious environmental problem in China, following the rapid industrialization of the nation
This study indicated that the supplement of micrometer particle size of HAP (mHAP) and nanometer particle size of HAP (nHAP) both significantly increased the soil pH compared to the unamended metals contaminated soil (Table 5)
The results showed that both mHAP and nHAP had significant effect on reducing the uptake of Pb, Zn, Cu, and Cr by pakchoi
Summary
Heavy metal pollution in the soil has become a serious environmental problem in China, following the rapid industrialization of the nation. A number of remediation methods have been developed in an attempt to control heavy metal pollution, including the use of organic manure, soil amendment addition, cultivation of heavy metal hyperaccumulator plants, and the application of agroecological engineering techniques [2, 3]. Supplementation of phosphate-based materials has been found to have a great effect on immobilizing Pb in contaminated soil and has recently become a commonly used technique due to its cost-effectiveness and decreased disruptive nature [4, 5]. Hydroxyapatite (HAP) is considered to be the most effective supplement among P-based materials and is commonly used in Pb-contaminated soil. It has been reported that HAP facilitates the remediation of Pb, but it is quite effective in immobilizing other heavy metals, such as Zn, Cd, and Cu [6, 7]. The overall effectiveness of using phosphate to immobilize metals and its mechanisms of action remain unknown
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
