狼尾草修复阿特拉津污染黑土的微生物生态学机制研究

A series of ecological and environmental problems which caused by the application of atrazine in black soil zone located in the northeast part of China has been aroused much more attention. Bioremediation has been considered as the most effective technology to solve the problem mentioned above. Some relative researches proved that Pennisetum could show better resistance to atrazine, so it could be selected as the resistant plant to repair atrazine polluted soil. However, the microbial ecology mechanism why Pennisetum could remove atrazine from the soil has been unclear. Aiming at this problem, this project chooses the black soil which suitable for agriculture as the test soil and select Pennisetum as the resistant plant. Then, investigate the response pattern of the typical physiological and ecological index of Pennisetum to atrazine pollution. On the basis of the results, this project will also study on the bioremediation effect of atrazine polluted black soil. Furthermore, some other details about the affection of Pennisetum root exudates on the atrazine migratory activity in soil, the atrazine enrichment ability of Pennisetum, the change of typical soil microbial characteristic and important physicochemical properties were also researched in this project. According to the results obtained from the researches mentioned above, the microbial ecology mechanism that Pennisetum remedied the atrazine polluted black soil could become clear. In addition, the project also could help us in better investigating the new mechanism and new theory about the bioremediation of atrazine pollution.

因除草剂阿特拉津在东北黑土地区广泛使用而产生的一系列生态环境问题受到了广泛关注。生物修复技术被认为是解决有机污染最有效的方法。相关研究证实狼尾草因具有良好的阿特拉津抗性而适宜作为抗性植物对阿特拉津污染土壤进行修复，然而当前有关狼尾草修复阿特拉津污染土壤的相关微生物生态学机制则尚不明确。针对上述问题，本项目选取最为适宜农业生产的黑土为供试土壤，以狼尾草为抗性植物，在明确狼尾草典型生长及生理生态指标对阿特拉津污染胁迫的响应规律基础上，开展狼尾草修复阿特拉津污染黑土的效果及其机制方面的研究。通过考察狼尾草根系分泌物对阿特拉津在土壤中迁移活性的影响、狼尾草对阿特拉津的吸收富集能力以及修复过程中根际土壤典型微生物特征及理化指标的变化等一系列的关键问题，进而形成狼尾草修复阿特拉津污染黑土的微生物生态学机制，以期探寻阿特拉津污染土壤生物修复的新机制和新理论。

针对阿特拉津在东北黑土地区广泛使用而产生的一系列生态环境问题，开展以黑土为供试土壤、狼尾草为抗性植物的阿特拉津污染黑土修复的微生物生态学机制。在明确狼尾草典型生长及生理生态指标对阿特拉津污染胁迫的响应规律基础上，进行狼尾草修复阿特拉津污染黑土的效果及其机制方面的研究。主要研究内容包括：（1）阿特拉津污染胁迫条件下狼尾草典型生长及生理生态特征变化的研究；（2）阿特拉津在狼尾草根际消减时空变化规律的研究；（3）狼尾草根系分泌物对土壤中阿特拉津迁移活性影响规律的研究；（4）污染土壤修复过程中狼尾草根际微生态特征的研究；（5）污染土壤修复过程中阿特拉津在狼尾草体内分布规律的研究等5个方面。本研究确定狼尾草对阿特拉津的耐受阈值为0-20 mg•kg-1的范围内。狼尾草可通过提升其体内典型抗氧化酶（SOD、APX、POD）的活性以及抗氧化非酶物质（ASA、GSH和GSSG）的含量来缓解阿特拉津对其所产生的氧化胁迫进而表现出上述的阿特拉津抗性。另外，狼尾草根系通过向其根系土壤环境中释放根系分泌物来改变阿特拉津在黑土环境的迁移特性，在上述过程中根系分泌物可以提升根基黑土对阿特拉津的吸附能力，进而减少其淋溶特性，研究证实土壤表面的阿特拉津大多集中在0-6cm的土层深度。根系作用可以明显的调节根区土壤的理化性质(酶活与土壤pH值)，同时提升根区微生物的代谢能力并选择性进化调节根区土壤环境中能够参与土壤养分循环与污染物降解过程的微生物的存在。综合上述研究，我们确定狼尾草修复阿特拉津污染黑土的主要生物学机制主要是通过在其阿特拉津抗性能力的保障作用下，其在阿特拉津污染黑土中一方面通过释放根系分泌物来减少其根系环境中阿特拉津的迁移能力，同时活化和提升其根系环境中微生物的代谢能力，进而实现了土壤中阿特拉津的去除。上述结果对于今后在原位条件下利用狼尾草修复阿特拉津污染土壤提供了必要的基础数据，也为探讨狼尾草对阿特拉津的耐受能力及土壤修复效果调控提供了理论基础。