稀土矿废弃地植被恢复过程中土壤微生物演变

以福建长汀典型离子型稀土矿堆浸冶炼废弃地作为研究对象,采取"空间代时间"的方法,对堆浸废弃地不同植物恢复年限样地土壤理化性质及微生物进行调查测定,分析植物恢复对稀土矿堆浸废弃地土壤理化特性及微生物的影响.结果表明：在植被恢复第3a和4a土壤理化性质显著高于未治理废弃地,但仍显著低于矿区周边未开采对照（P<0.05）.植被恢复年4a以后,长汀稀土矿废弃地土壤理化性质则呈下降趋势,但仍显著高于未治理废弃地（P<0.05）.长汀稀土矿堆浸废弃地不同植被恢复年限土壤细菌丰度及多样存在一定差异.随植被恢复年限的增加,土壤细菌多样性及丰度降低,但一些特殊细菌群如γ-变形菌纲（Gammaproteobacteria）、a-变形杆菌纲（Alphaproteobacteria）、酸杆菌门（Acidobacteria）、蓝藻菌门（Cyanobacteria）等在不同植被恢复年限样地中其相对丰度明显增加.具有固氮作用的蓝藻菌门（Cyanobacteria）随着植被恢复年限的增加,其相对丰度降低.广古菌门（Euryarchaeota）仅存在于未开采对照样地;土壤寡营养细菌酸杆菌门（Acidobacteria）随植被恢复年限的增加,相对丰度呈增大趋势.土壤中优势菌群广古菌门（Euryarchaeota）、厚壁菌门（Firmicutes）、β-变形菌门（Proteobacteria）、Methanobacterium属、罗尔斯通菌属（Ralstonia）与土壤pH、全磷、全钾、速效磷等呈正相关.土壤pH值、全磷、全钾等是影响广古菌门（Euryarchaeota）、厚壁菌门（Firmicutes）等细菌菌群多样性及相对丰度变化的重要因素.以上结果表明,离子型稀土矿堆浸废弃地植被恢复治理到3~4a时,应采取防治措施对其进行人工抚育管理,否则可能会出现前期恢复后期退化的问题.

Soil physicochemical characteristics and microbial evolution during vegetation restoration in ionic rare earth ore heap leaching waste land

In order to mitigate of the sever soil erosion and degradation in ecological environment in the rare earth mining area, a vegetation restoration project in the abandoned land of rare earth mining area in Changting, Fujian was implemented several years ago. Physical and chemical properties and microorganisms' composition of soil in the heap leaching of abandoned land of rare earth mining, Changting after different years of vegetation restoration were analyzed. The results showed that physical and chemical properties of soil after three and four years of vegetation restoration were significantly higher than those in the untreated abandoned land (without restoration) but lower than the unmined area (P<0.05). After 4years of vegetation restoration, the physical and chemical properties of soil in the abandoned land of rare earth mining area, Changting showed a downward trend, but still significantly higher than that of untreated abandoned land (P<0.05). Differences were identified in the abundance and diversity of soil bacteria of abandoned land of rare earth mining between different years of vegetation restoration. The diversity and abundance of soil bacteria decreased with the years of vegetation restoration,. However, the relative abundance of some special bacterial groups such as Gamma proteobacteria, Alphaproteobacteria, Acidobacteria and Cyanobacteria significantly increased in the stands of different years of vegetation restoration. The relative abundance of Cyanobacteria, a type of bacteria of nitrogen fixing, decreased along with the process of vegetation recovery. Euryarchaeota only existed in the unmined land, and Acidobacteria increased with the increase of years of vegetation restoration. The dominant flora in soil, Euryarchaeota, Firmicutes, Proteobacteria, Methanobacterium and Ralstonia, were positively correlated with soil pH, total phosphorus, total potassium and available phosphorus. The diversity and relative abundance of bacterial flora such as Euryarchaeota and Firmicutes were significantly affected by the physical and chemical properties of soil. In conclusion, the artificial prevention and control measures should be taken after 3-4 years of vegetation restoration in the heap leaching land of ion-type rare earth mining area to mitigate the degradation.