同位素标识蜈蚣草对Pb污染土壤修复的调控机理探索

Phytoremediation was a kind of green remediation technology in removing environmental pollutants and has attracted a wide spread attention by research scholars. The arsenic accumulation and tolerance mechanism of Pteris vittata L., a multi-metal hyperaccumulator, has been studied by many scientific researches. But so far, there was little research on Pb accumulation and tolerance mechanism of Pteris vittata L. under natural and treatment conditions, especially for Pteris vittata L. that was treated with activating agent, which has important theory meaning for improving the extraction efficiency of Pb by using activating agent. With good experimental conditions and valuable research results from previous studies, we conduct present research to make clear on how does Pteris vittata L. activate Pb from the contaminated soil, as well as accumulate and transport Pb to its fronds, with the aid of Pb isotope labeling technology. The hyperaccumulation characteristic of Pb in Pteris vittata L. was taken as the research object. The Pb isotope labeling technology was used to identify the ligand sites between soil residual Pb and activating agent, to disclose the transferring and transforming behavior of different forms of Pb in the contaminated soil under the effect of activating agent. Meanwhile, the Scanning SRXRF Microprobe was adopted for plant cell of Pteris vittata L., to investigate the transferring and transport behavior of Pb in pteris vittata, to reveal why this hyperaccumulator could accumulate and tolerate large quantities of Pb that was activated from the contaminated soil. The result has important theoretical significance in improving the phytoremediation efficiecncy of Pb by pteris vittata, it also has important application value in remediating Pb contaminated soil.

金属矿周边多金属污染土壤亟待修复，利用超富集植物提取土壤中的重金属是具有潜力的土壤修复技术之一。项目基于砷超富集植物蜈蚣草对铅的富集能力，研究活化剂对蜈蚣草吸收土壤铅的促进能力，并采用稳定同位素标识技术，从土壤铅活化和植物体内铅代谢两方面，探讨蜈蚣草对Pb污染土壤修复的调控机理。项目以蜈蚣草对Pb的超富集特征为研究目标，利用Pb稳定同位素标记技术探索活化剂对土壤残渣态Pb的"靶位"活化机制以及活化剂作用下土壤Pb各形态之间的迁移和转化特征；结合SRXRF技术从细胞的水平上研究土壤"靶位"活化Pb在蜈蚣草体内的迁移-转运机制，揭示蜈蚣草对土壤活化Pb的代谢机制，探索蜈蚣草对Pb污染土壤修复的调控机理。研究结果对于提高植物修复效率，治理Pb污染土壤具有重要的理论价值和现实意义。

蜈蚣草对铅（Pb）、镉（Cd）也具有较强的耐性或富集能力。活化剂可以提高植物修复的修复效率，缩短修复周期，一直是人们研究的热点问题。本研究通过室内培养、盆栽试验以及野外大田试验，揭示重金属活化剂作用下，土壤Pb的活化机制以及蜈蚣草对Pb的富集和耐性机理。项目在土壤重金属数据分析、土壤重金属活化机制、同位素示踪Pb在植物体内的迁移-转运等方面取得一定的成果。.EDTA显著提高了蜈蚣草体内Pb的浓度与积累量，其中羽叶的Pb浓度在潮土与棕壤中分别为对照的33.9和5.97倍，积累量分别为对照的9.22与1.18倍。EDTA也显著提高了蜈蚣草体内Cd的浓度，其中羽叶Cd的浓度分别为对照的9.16和2.40倍。磷酸二氢铵与柠檬酸在两种土壤中对蜈蚣草吸收富集Pb、Cd均无促进作用。在两种As污染土壤条件下，磷酸二氢铵、柠檬酸均能显著提高蜈蚣草生物量和体内As的含量。磷酸二氢铵与柠檬酸可将土壤中的残渣态As转化为非专性吸附态与专性吸附态，进而提高了土壤中As的生物有效性。本研究可为蜈蚣草应用于Pb-Cd复合污染土壤修复和应用土壤活化剂来提高其修复效率提供理论依据，同时为利用活化剂技术提高蜈蚣草修复污染土壤提供一条可行的思路。.通过野外调查，分析典型区域小麦籽粒、根际土壤以及小麦生长季期间的大气降尘不同介质中Pb含量以及同位素比值，发现大气降尘是小麦籽粒Pb的主要来源途径，小麦从大气降尘中吸收Pb是籽粒Pb的主要迁移-转运途径。研究结果为了解植物吸收重金属的关键部位提供新的认识。.提出一种甄别土壤重金属异常数据的方法，可以有效识别出土壤重金属数据中由于为系统误差和人为误差导致的异常数据，在增加有限样本量和分析时间的前提下提高调查数据质量，为保障数据质量提供有效的识别工具。