平远稀土尾矿植物重金属富集特性的研究

Study on the Heavy Metal Accumulation Characteristics of Plants in Pingyuan Rare Earth Tailings

摘要: 本研究以梅州市平远县仁居镇废弃稀土矿区为对象，分析5种优势植物，五节芒(Miscanthus floridulus (Lab.) Warb. ex Schum. et Laut.)、芒萁(Dicranopteris pedate (Houtt.) Nakaike)、雀稗(Paspalum thunbergii Kunth ex Steud.)、黑莎草(Gahnia tristis Nees Hooker & Arnott)对Pb、Cu、Zn、Cd、As等重金属及稀土元素的吸收、转运与富集特性，并评价土壤污染程度及植物食用安全性。结果表明，尾矿土与复垦土均存在Pb、Mn、Zn轻度污染，稀土元素以轻稀土为主且复垦土污染略重；芒萁对Cu (BCF = 2.936)和As (BCF = 2.881)富集能力最强，对Mn (TF = 7.29)、As (TF = 2.24)转运能力突出；黑莎草对Cd (BCF = 1.826)富集优势显著；五节芒对Cr、Ni转移系数较高。5种植物地上部重金属含量均低于国家饲料卫生标准，食用风险低。研究可为粤东北稀土尾矿土壤植物修复与植被重建提供科学依据，对区域生态可持续修复具有参考价值。

Abstract: This study taken the abandoned rare earth mining area in Renju Town, Pingyuan County, Meizhou City as the object, analyzed the absorption, transport, and enrichment characteristics of five dominant plants, Miscanthus floridulus (Lab.) Warb. ex Schum. et Laut., Dicranopteris pedata (Houtt.) Nakaike, Paspalum thunbergii Kunth ex Steud., and Gahnia tristis Nees Hooker & Arnott, on heavy metals and rare earth elements such as Pb, Cu, Zn, Cd, As, and evaluated the degree of soil pollution and plant food safety. The results showed that both tailings soil and reclaimed soil were mildly polluted with Pb, Mn, and Zn, and rare earth elements were mainly light rare earth elements, with reclaimed soil being slightly more polluted; Dicranopteris pedata had the strongest enrichment ability for Cu (BCF = 2.936) and As (BCF = 2.881), and outstanding transport ability for Mn (TF = 7.29) and As (TF = 2.24); Gahnia tristis had a significant advantage in Cd (BCF = 1.826) enrichment; Miscanthus floridulus had a higher transfer coefficient for Cr and Ni. The heavy metal content in the aboveground parts of 5 plant species was lower than the national feed hygiene standard, indicating low food risk. The research can provide scientific basis for soil vegetation restoration and vegetation reconstruction of rare earth tailings in northeastern Guangdong, and has reference value for regional ecological sustainable restoration.