遮阴对伴矿景天Cd、Pb、Zn累积特征的影响

Effect of shading on the accumulation of Cd, Pb and Zn of Sedum plumbizincicola

  • 摘要: 为促进伴矿景天(Sedum plumbizincicola)在云南高原土壤污染地区修复实践中的应用, 本文在云南怒江兰坪铅锌矿区矿渣地开展种植伴矿景天的大田试验, 设置遮阴处理(光照强度降低25%), 以自然光照为对照, 测定植株生物量、亚细胞组分和化学形态镉(Cd)、铅(Pb)、锌(Zn)含量及全量, 研究遮阴处理对伴矿景天Cd、Pb、Zn累积特征的影响。结果表明: 1)遮阴处理导致伴矿景天茎、叶中Cd、Pb、Zn含量和累积量均显著降低(P<0.05或P<0.01), 含量降幅范围为15.2%~52.1%, 累积量降幅范围为17.6%~67.4%; 且遮阴条件下伴矿景天Cd、Zn的富集系数和转移系数显著小于未遮阴条件下生长的伴矿景天(P<0.05)。2)遮阴条件下, 伴矿景天植株叶细胞壁Cd含量显著降低(P<0.05), Pb含量显著增加(P<0.05); 且伴矿景天茎、叶中细胞器和可溶部分Zn含量均显著降低(P<0.05), 降幅范围为11.8%~57.3%。3)伴矿景天茎、叶中Zn以醋酸提取态(FHAc)和盐酸提取态(FHCl)为主, Cd、Pb以氯化钠提取态(FNaCl)为主; 且遮阴处理导致伴矿景天叶片中FHAc-Cd含量极显著增加(P<0.01), 去离子水提取态(FW) Cd含量显著降低(P<0.05或P<0.01); 茎、叶中乙醇提取态(FE) Zn和FHAc-Zn、FHCl-Zn含量均极显著降低(P<0.01)。综上所述, 遮阴导致伴矿景天的液泡区隔化和细胞壁固持作用降低, 且其体内难溶的磷酸盐类惰性态重金属含量减少, 最终降低伴矿景天对Cd、Zn的富集和转运能力。

     

    Abstract: This study aimed to investigate the effect of shading on the accumulation characteristics of Cd, Pb, and Zn in Sedum plumbizincicola. S. plumbizincicola has strong tolerance and uptake ability for Zn and Cd, and is a promising remediation plant for Zn- and Cd-contaminated soil. To promote the application of S. plumbizincicola in remediation practices of heavy metal polluted soil of Pb-Zn mining area in Yunnan Province, S. plumbizincicola was planted in the slag field of the Lanping Pb-Zn mining area in Nujiang, Yunnan Province. In the experiment, a shade net was laid to reduce the light intensity by 25%, and the effects of shading on plant biomass and chlorophyll; contents and accumulation of Cd, Pb, and Zn in different organs; as well as subcellular distrubition of Cd, Pb and Zn in leaves and stems were investigated. The results indicated that the shading treatment significantly reduced the Cd, Pb, and Zn contents in the stems and leaves of S. plumbizincicola (P<0.01); and significantly decreased the accumulation of Cd, Pb, and Zn in the stems and leaves by 17.6%−67.4% (P<0.05 or P<0.01). Moreover, compared with the no-shading condition, the Cd and Zn enrichment and transfer coefficients of S. plumbizincicola were significantly reduced when grown under shading conditions (P<0.05). The shading treatment significantly decreased the transport coefficient and biological transfer factor of Pb (P<0.05). Under the shading treatment, the Cd content in the leaf cell wall of S. plumbizincicola was significantly reduced (P<0.05), while the Pb content significantly increased (P<0.05). At the same time, the content of Zn in the organelles and soluble parts of S. plumbizincicola was significantly reduced by 11.8%−57.3% (P<0.05). In the stems and leaves of S. plumbizincicola, the HAc-extractable and HCl-extractable forms of Zn, and NaCl-extractable forms of Cd and Pb were dominant. In addition, the shading treatment increased the content of HAc-extractable Cd in the leaves of S. plumbizincicola by three times (P<0.01) and produced a significant reduction in the content of the water-extractable Cd (P<0.05, P<0.01). In addition, the ethanol-, HAc-, and HCl-extractable Zn forms were reduced by 30.2%−58.6% in the leaves of S. plumbizincicola (P<0.01). Thus, shading reduced vacuolar compartmentalization and cell wall retention in S. plumbizincicola as well as the content of insoluble phosphate-like inert heavy metals, and ultimately reduced the ability of S. plumbizincicola to enrich and transport Cd and Zn.

     

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