Zhu Guang-Xu, Xiao Hua-Yun, Guo Qing-Jun, Zhang Zhong-Yi, Yang Xi, Kong Jing
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Huan Jing Ke Xue. 2017 Jul 8;38(7):3054-3060. doi: 10.13227/j.hjkx.201612249.
Field investigation on the content of heavy metals in soils and three types of widely distributing compositae plants( L.) 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. L. and 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 were 159.6 mg·kg and 219.5 mg·kg, respectively, which exceeded the threshold of Cd hyperaccumulator. Thus, 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 , more Cd was located in the vacuolus and cellular soluble parts in L. and . 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 L. and were likely to possess a higher tolerance and accumulation of Cd.
对广西壮族自治区阳朔铅锌尾矿农田土壤及三种广泛分布的菊科植物（L.）中的重金属含量进行了实地调查，并采用差速离心技术和连续化学提取法研究了这些植物中重金属的亚细胞分布和化学形态。结果表明，尾矿农田土壤受到镉、铅和锌的高度污染，其含量分别比土壤环境质量国家标准（二级）各自的值高37.7、5.7和8.9倍。所分析植物中的镉、铅和锌含量超出正常范围。L.和显示出对镉具有较强的耐受、积累和转运能力，它们可作为研究区域及一些相关区域镉植物修复的先锋植物。此外，的茎和叶中镉含量分别为159.6 mg·kg和219.5 mg·kg，超过了镉超富集植物的阈值。因此，可被视为镉超富集植物。植物中镉、铅和锌的总量大部分存在于可溶部分和细胞壁中，而只有少量分布在细胞器中。至于化学形态分布，镉、锌和铅在植物的根和地上部分均以氯化钠、醋酸和盐酸可提取形态为主。因此，细胞壁结合、液泡区室化以及主要以低活性化学形态分布被认为是研究植物对重金属耐受的主要机制。观察到三种菊科植物中镉的亚细胞分布及其化学形态存在差异。与的地上部分相比，更多的镉存在于L.和的液泡和细胞可溶部分。此外，地上部分活性化学镉的比例低于根中的比例。这些结果表明，镉的亚细胞分布和化学形态与植物种类有关，也表明L.和可能对镉具有更高的耐受性和积累能力。
