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以铁尾矿区人工营造的沙棘-桑树混交林为研究对象,从沙棘和桑树的各个部位(根、干、枝、叶、皮)、单个植株以及混交林生态系统结构(乔木层、草本层、枯落物层、土壤层)3个层面,测定分析Fe、Mn、Cu、Zn、Cr、Pb、Ni、Cd等8种重金属离子的积累、分配和富集特征,为铁尾矿重金属污染土壤的森林修复生态系统构建以及保障与维持系统的平衡、可持续性提供科学依据。2个树种植株的各个部位,均以树根和树叶中的重金属元素含量较高,其次为树皮和树枝,树干中的含量最低,而且2个树种植株的根系对8种重金属元素的富集能力普遍较强,树皮和树叶对Pb、Cr、Cd的富集能力高于其他部位。2个树种在单株水平上均对土壤Ni的富集能力最强,对Fe的富集能力最弱,但沙棘对Fe、Mn、Cu、Cr、Pb和Cd的平均富集能力比桑树强,而桑树对Ni的富集能力比沙棘强,二者对Zn的平均富集能力相当;沙棘单株对8种重金属元素的总积累量为3.094 2×10-3kg/株,桑树为2.402 0×10-3kg/株。2个树种的混交林地土壤中,Fe元素贮存量占总贮存量的98.79%,Mn元素占0.94%,其他6种元素合计共占0.27%;沙棘根际土壤重金属的平均含量低于桑树,特别是Cd含量低于桑树。混交林生态系统结构各层次的重金属元素贮存量从大到小依次是土壤层、枯落物层、乔木层、草本层。以上研究结果提示,在铁尾矿上营建对重金属元素富集能力强,而且树种间对不同重金属元素的富集具有互补性的沙棘-桑树混交林,是一种较优的治理铁尾矿区土壤重金属污染的模式。
Taking the artificial seabuckthorn-mulberry mixed plantation built in the iron tailing area as the research object, from the different parts of the sea buckthorn and the mulberry (root, stem, branch, leaf, skin), single plant and mixed forest ecosystem structure Litter layer and soil layer), the accumulation, distribution and enrichment characteristics of 8 heavy metal ions such as Fe, Mn, Cu, Zn, Cr, Pb, Ni and Cd were determined and analyzed. Provide the scientific basis for the construction of the forest restoration ecosystem and the balance and sustainability of the system of maintenance and maintenance. The contents of heavy metal elements in the roots and leaves of the two tree species were higher than others, followed by the barks and branches, the lowest in the trunk, and the roots of the two tree species were enriched in eight heavy metal elements The ability is generally stronger, bark and leaves of Pb, Cr, Cd enrichment ability than other parts. The two species had the strongest enrichment ability on soil Ni and the weakest ability on Fe accumulation at the single plant level, but the average enrichment ability of seabuckthorn to Fe, Mn, Cu, Cr, Pb and Cd was higher than that of Mulberry , While the mulberry tree had stronger enrichment ability on Ni than sea buckthorn, and the average enrichment ability of Zn on the two was similar. The total accumulation of eight heavy metal elements in seabuckthorn was 3.094 2 × 10-3kg / plant and mulberry was 2.402 0 × 10 -3 kg / plant. The content of Fe element in the soil of the mixed forest of two species accounted for 98.79% of the total storage, Mn element accounted for 0.94%, the other six elements accounted for a total of 0.27%; Seabuckthorn Rhizosphere soil heavy metal content is lower than mulberry, especially The content of Cd is lower than mulberry. The storage of heavy metal elements at different levels of the ecosystem structure in the mixed forest ranged from soil layer to litter layer, arbor layer and herb layer. The above results suggest that the establishment of sea-buckthorn-mulberry mixed forest with strong enrichment of heavy metal elements on the iron tailings and the complementarity of different heavy metal elements among the species is a better method to treat the soil of iron tailings Heavy metal pollution mode.