摘要
摘要:随着经济和社会的发展，土壤重金属污染对粮食安全及人类的身体健康构成了巨大的威胁，而目前对于土壤重金属污染的治理主要以植物修复为主。为了寻找适宜修复Cu、Pb复合污染土壤的牧草，采用盆栽试验法，将试验的植物设置9组处理：1组对照组（CK），不添加任何重金属盐；4组单一污染，即单一Cu低（Cu₁，200 mg·kg^-1）、高浓度（Cu₂ 400 mg·kg^-1），单一Pb低（Pb₁ 300 mg·kg^-1）、高浓度（Pb₂ 800 mg·kg^-1）；4组Cu、Pb复合污染（Cu₁Pb₁、Cu₁Pb₂、Cu₂Pb₁、Cu₂Pb₂）。通过比较紫花苜蓿（Medicago sativa）、黑麦草（Lolium perenne）、狼尾草（Pennisetum alopecuroides）的适应能力和富集特征，研究了这3种常见牧草植物对受Cu、Pb复合污染土壤的修复效果。结果表明：1）紫花苜蓿地上部和根部生物量均在Pb₁处理组时最大，显著高于其他处理组；黑麦草地上部生物量在Cu₁Pb₁处理组最大，根部生物量在Pb₁处理组最大；狼尾草地上部生物量在Cu₂Pb₂处理组最大，根部生物量在Cu₂处理组最大。2）Cu单一污染下，狼尾草抗性系数最大；Pb单一污染下，紫花苜蓿抗性系数最大；Cu-Pb复合污染下，狼尾草的抗性系数较大。高浓度Cu处理组3种牧草植物的地上部生物量、根部生物量和抗性系数均呈现：狼尾草>黑麦草>紫花苜蓿，且狼尾草显著大于黑麦草和紫花苜蓿。3）种植3种牧草植物后，土壤重金属Cu、Pb含量均有所降低。在一定浓度下，土壤Cu-Pb重金属间会相互促进对方在牧草植物中的吸收。4）3种牧草中紫花苜蓿地上部对Cu的富集系数在Cu₂Pb₂处理组最大，达1.61；黑麦草根部对Cu的富集系数在Cu₂Pb₂处理组最大，达3.80；3种牧草地上部和根部对Pb的富集系数只在黑麦草根部的Cu₁Pb₁处理组时大于1，达1.46。5）黑麦草对Pb的吸收能力较强，且主要积累在根系；紫花苜蓿对Cu-Pb复合污染综合修复效果最好。紫花苜蓿和黑麦草分别在Cu-Pb复合污染和Pb单一污染土壤中对Pb的转运系数大于1，分别为2.72和2.06，反映其对土壤中的Pb具有富集潜力。综合表明，黑麦草对重金属Pb具有较强的耐性，在Pb单一污染土壤的植物修复及尾矿废弃地的植被重建中，可优先作为选择的材料；紫花苜蓿对重金属Cu、Pb均具有较强的耐性，在重金属Cu单一或Cu-Pb复合污染土壤的植物修复及尾矿废弃地的植被重建中，可优先作为选择的材料。
关键词:紫花苜蓿/
黑麦草/
狼尾草/
重金属/
Cu/
Pb/
复合污染/
富集/
转运
Abstract:With rapid socio-economic development, the problem of heavy metal contamination of soils is increasingly threatening food security and human health. So far, phytoremediation has been the main mode of treatment of soils for heavy metal pollution. To develop pastures suitable for remediation of complex Cu and Pb contaminated soils, a pot experiment consisting of 9 treatments was set up. The control (CK) was not treated with heavy metal salts. Four other treatments had low and high pollutions of single metals including Cu (Cu₁:200 mg·kg^-1 Cu²⁺; Cu₂:400 mg·kg^-1 Cu²⁺), Pb (Pb₁:300 mg·kg^-1 Pb²⁺; Pb₂:800 mg·kg^-1 Pb²⁺). The other four treatments consisted of both Cu and Pb pollutions of Cu₁Pb₁, Cu₁Pb₂, Cu₂Pb₁ and Cu₂Pb₂. The effects of pastures (forages) plantation on the Cu and Pb contaminated soil remediation were determined by comparing the adaptability and enrichment characteristics of alfalfa (Medicago sativa), ryegrass (Lolium perenne) and pennisetum (Pennisetum alopecuroides). The results showed that:1) the aboveground and belowground biomasses of M. sativa were largest under Pb₁ treatment, which were significantly larger than those for the other treatments. The aboveground biomass of L. perenne was largest under Cu₁Pb₁ treatment and belowground biomass of L. perenne largest under Pb₁ treatment. The aboveground biomass of P. alopecuroides was largest under Cu₂Pb₂ treatment and belowground biomass of P. alopecuroides largest under Cu₂ treatment. 2) When the soil was treated solely with Cu, the resistance coefficient of P. alopecuroides was largest among the three pasture species. Then when the soil was treated solely with Pb, the resistance coefficient of M. sativa was largest. For Cu and Pb combined treatment, the resistance coefficient of P. alopecuroides was largest. The order of aboveground biomass, belowground biomass and resistance coefficient of the three pasture plants under high Cu concentration treatments was P. alopecuroides > L. perenne > M. sativa. Then the aboveground biomass, belowground biomass and resistance coefficient of P. alopecuroides were significantly higher than those of L. perenne and M. sativa. 3) Soil contents of Cu and Pb decreased after planting the forage plants. At a certain concentration, soil Cu-Pb promoted the absorption of each other by the pasture plants. 4) The enrichment coefficient of Cu for aboveground biomass of M. sativa was highest under Cu₂Pb₂ treatment, which was 1.61. Then the enrichment coefficient of Cu for belowground biomass of L. perenne was highest under Cu₂Pb₂ treatment, which was 3.80. Only the enrichment coefficient of Pb for aboveground and belowground biomass of L. perenne exceeded 1.0, reaching 1.46. 5) The absorption ability of Pb by L. perenne was stronger and accumulated mainly in belowground biomass. M. sativa had the best comprehensive repair effect of complex Cu-Pb pollution. The transport coefficients of Pb in M. sativa and L. perenne were higher than 1.0 in complex Cu-Pb and single Pb polluted soils, respectively, and were 2.72 and 2.06, which reflected their respective potentials for enrichment of Pb in the soil. Thus L. perenne had a stronger tolerance to Pb pollution and was therefore a better remedy for Pb-polluted soils. M. sativa had a stronger tolerance to Cu and Pb and was therefore a better remedy for soils polluted with single Cu or composite Cu-Pb.
Key words:Medicago sativa/
Lolium perenne/
Pennisetum alopecuroides/
Heavy metal/
Cu/
Pb/
Combined pollution/
Enrichment/
Translocation



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