Search

Broussonetia papyrifera, Cryptomeria fortunei, Arundo donax, and Robinia pseudoacacia were planted on a zinc smelting slag site. The habitat conditions and spatial distribution of arsenic (As) and antimony (Sb) in slag were analyzed after seven years of restoration. The results showed that the pH, conductivity (EC), and moisture content of phytoremediated slag were lower than those of the control slag. The redox potential (Eh) and EC decreased with increasing slag depth. Phytostabilization significantly increased the contents of total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), available phosphorus (AP), and dissolved organic carbon (DOC) in slag. TN, AN, AP, and DOC in slag showed obvious surface polymerization. Phytostabilization increased the content of calcite and gypsum in the slag. As and Sb concentrations were significantly lower than control slag, with an average decrease of 651–844 and 422–693 mg·kg −1, respectively. Residual As and Sb in phytoremediated slag was the most present form, the proportion of which was higher than that in the control slag. The proportions of calcium-bound and aluminum-bound As and Sb were lower. The contents of arsenic and antimony in plants had lower levels and followed the order of roots > leaves > stems. As and Sb showed a strong positive correlation with pH, EC, moisture content, and a negative correlation with TN, TP, AN, AP, and DOC. In summary, phytostabilization significantly improved slag site conditions and reduce As and Sb available concentrations. Novelty statement Co-contamination of As and Sb is common in mining areas because of similar chemical properties. There are only few reports on the effects of matrix modification and phytoremediation (without additional soil cover) on the soil physicochemical properties, the spatial distribution, and the bioavailability of As and Sb in zinc slag with an alkaline pH. The research determined that phytostabilization significantly improved slag site conditions and reduce As and Sb available concentrations. The results obtained can be used as necessary information for the large-scale ecological restoration or vegetation reconstruction of zinc smelting slag yards. [ABSTRACT FROM AUTHOR]

We studied the speciation of arsenic and antimony in the rhizosphere of 6 pioneer plants grown in zinc smelting slag to understand the main affecting factors of phytoremediation. Compared with the control slag, the pH of rhizosphere decreased significantly (p < 0.05) and the DOC content increased significantly (p < 0.05). Overall, the contents of arsenic (except Photinia serrulata and Lolium perenne) and antimony in the rhizosphere were lower than those of control slag. The proportions of residual arsenic and antimony in the rhizosphere were the highest and significantly higher than control slag. Exchangeable state, aluminum-bound state and calcium-bound state were lower than control slag. The contents of arsenic and antimony in plants were normal and followed the order of roots > leaves > stems. Arsenic and antimony were significantly positively correlated with Free iron and aluminum oxides and negatively correlated with DOC. After 7 years of phytoremediation, the content and bioavailability of arsenic and antimony in the rhizosphere were significantly reduced and have a normal contents in plants. It is speculated that phytoremediation increases the migration of arsenic and antimony to the surrounding area, and Photinia serrulata and Lolium perenne exhibited the best performance on stabilise arsenic in slag. [ABSTRACT FROM AUTHOR]