| 铅锌尾矿污染区3种菊科植物体内重金属的亚细胞分布和化学形态特征 |
| 摘要点击 2437 全文点击 871 投稿时间：2016-12-29 修订日期：2017-01-19 |
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| 中文关键词 重金属污染 铅锌尾矿 亚细胞分布 化学形态 菊科植物 |
| 英文关键词 heavy metal pollution lead-zinc tailings subcellular distribution chemical forms compositae plants |
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| 中文摘要 |
| 通过实地调查分析广西阳朔某铅锌尾矿污染农田自然生长的3种常见菊科植物野艾蒿、胜红蓟和野茼蒿体内的重金属含量，并采用差速离心与化学试剂提取法分析重金属在植物中的亚细胞分布及其存在的化学形态，探究菊科植物对重金属的积累、耐性特征和机制.结果表明，污染区土壤受Cd、Pb、Zn这3种重金属污染严重，其含量分别比国家土壤环境二级标准（GB 15618-1995）超标37.7、5.7和8.9倍，植物体内Cd、Pb和Zn含量都超过正常范围.野茼蒿和胜红蓟对Cd具有较强的迁移能力和富集能力，适用于Cd污染土壤的生态修复.此外，野茼蒿的茎和叶中Cd的含量分别为159.6 mg·kg-1和219.5 mg·kg-1，超过Cd超富集植物的临界标准，可见野茼蒿完全具有Cd超富集植物的基本特征，是Cd超富集植物.3种菊科植物地下部和地上部的Cd、Pb和Zn主要分布在液泡可溶组分和细胞壁中，而在细胞器中的分布较少.植株中大部分的重金属以迁移性较低的氯化钠提取态、醋酸提取态和盐酸提取态存在.因此，液泡区隔化、细胞壁固持和重金属以低活性的化学形态为主可能是3种菊科植物应对重金属胁迫的重要耐性机制.与野艾蒿相比，胜红蓟和野茼蒿茎叶中的Cd更多地贮存在液泡中，且地上部"活性态"Cd的积累比例低于根系，这些很可能是胜红蓟和野茼蒿忍耐和富集镉的重要途径. |
| 英文摘要 |
| Field investigation on the content of heavy metals in soils and three types of widely distributing compositae plants(Artemisia lavandulaefolia, Ageratum conyzoides L., Crassocephalum crepidioides) in lead-zinc tailings farmland of Yangshuo, Guangxi Zhuang Autonomous Region was carried out, and the differential centrifugation technique and sequential chemical extraction method were used to study the subcellular distribution and chemical forms of heavy metals in these plants. The results indicated that the soil in the tailings farmland was highly contaminated by Cd, Pb and Zn, and their concentrations were 37.7, 5.7 and 8.9 times higher than their respective values of national standard for soil environment quality(GradeⅡ). The contents of Cd, Pb and Zn in the analyzed plants exceeded the normal ranges. Ageratum conyzoides L. and Crassocephalum crepidioides showed strong capability in tolerance, accumulation and transport of Cd, and they could be used as pioneer plants for Cd-phytoremediation in study area and some related areas. In addition, Cd concentrations in the stem and leave of Crassocephalum crepidioides were 159.6 mg·kg-1 and 219.5 mg·kg-1, respectively, which exceeded the threshold of Cd hyperaccumulator. Thus, Crassocephalum crepidioides can be regarded as a Cd-hyperaccumulator. Majority of total Cd, Pb and Zn were found in soluble fraction and cell wall in the plants, while only a small quantity were distributed in organelles. As for chemical forms distribution, Cd, Zn and Pb predominated NaCl-, HAC-, and HCl-extractable forms both in roots and shoots of the plants. Therefore, cell wall binding, vacuolar compartmentalization and distribution mainly in lower active chemical forms were supposed to be the main mechanisms for tolerance to heavy metals in the study plants. A difference of Cd subcellular distribution and its chemical forms in the three Compositae plants was observed. Compared with the shoot of Artemisia lavandulaefolia, more Cd was located in the vacuolus and cellular soluble parts in Ageratum conyzoides L. and Crassocephalum crepidioides. Moreover, the proportion of active chemical Cd in the shoots was lower than that in the roots. These results showed that the subcellular distribution and chemical forms of Cd were related to the plant species,and also indicated Ageratum conyzoides L. and Crassocephalum crepidioides were likely to possess a higher tolerance and accumulation of Cd. |
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