城市污泥堆肥强化蜈蚣草吸收转运砷的机理

The key problem in phytoextraction of arsenic contaminated soil is the low bioavailability. Increasing the phytoavailability of arsenic in soils is one of important strategies to improve the extraction of arsenic for P. vittata and thus accelerating remediation efficiency. The compost from sewage sludge was been reported to enhance the uptake and accumulation of arsenic in P. vittata, but the mechanisms behind this phenomenon remain unclear. Therefore, the influence of compost from sewage sludge on the composition and concentration of root exudate will be determined by ion chromatography. Meanwhile, the effect of compost on the abundance and diversity of functional gene microorganism will be measured using high-throughput sequencing technology. Then the mechanism of arsenic mobilization in the rhizosphere soils was clearly demonstrated. The arsenic morphological distribution of organ of P. vittata was determined using synchrotron radiation (XANES) and X-ray fluorescence spectra (μ-XRF), and then the mechanisms of the uptake and transportation of arsenic in the organ of P. vittata was explained. The mechanism of compost from sewage sludge enhancing the accumulation of arsenic by P. vittata will be revealed from the mobilization of arsenic in rhizosphere soils and the transportation of arsenic in P. vittata. The results of this study are expected to provide theoretical basis practical guidance for the safe utilization of compost and enhanced phytoremediation of arsenic-contaminated soils.

砷污染土壤的植物萃取修复存在砷有效性低的技术瓶颈，非常有必要采用辅助手段强化植物萃取。城市污泥堆肥已被证明能够增强蜈蚣草对砷的富集，但其强化机理尚不清晰。本项目通过离子色谱技术分析城市污泥堆肥对蜈蚣草根系分泌物组分和产生量的影响，利用高通量Illumina测序技术分析城市污泥堆肥对蜈蚣草根际土壤功能基因微生物的影响，结合同步辐射(XANES)和X射线荧光光谱(μ-XRF)从微区和分子层面分析根际土壤砷的微观结构，揭示城市污泥堆肥提高蜈蚣草根际土壤砷有效性的机理；利用XANES和μ-XRF研究城市污泥堆肥调控下蜈蚣草各器官砷形态分布，阐明城市污泥堆肥对蜈蚣草吸收转运活化砷的影响机制。本项目从城市污泥堆肥调控下蜈蚣草根际土壤砷活化和蜈蚣草吸收转运活化砷的角度揭示城市污泥堆肥强化蜈蚣草富集砷的机理。研究成果为城市污泥堆肥的安全利用和砷污染土壤的植物修复技术提供了理论依据和实践指导。

中文摘要：本研究以砷超富集植物蜈蚣草为研究对象，通过室内盆栽试验，开展城市污泥堆肥强化蜈蚣草吸收转运砷的作用机制研究。研究取得的主要成果如下：(1)研究不同城市污泥堆肥处理对蜈蚣草根际土壤砷活化的影响，结果表明不同城市污泥堆肥添加量处理使得蜈蚣草根际土壤砷的非专性吸附态比例提高57.7%~396.2%，土壤溶液砷含量提高30.69%~93.49%；(2)研究了不同城市污泥堆肥对蜈蚣草根际土壤理化性质的影响，结果表明不同城市污泥堆肥添加量处理能够提高根际土壤有机质和氮磷钾含量，提高土壤pH值，且土壤有机质、pH值与土壤溶液砷含量显著相关，说明土壤有机质和pH值是蜈蚣草根际土壤砷活化的关键理化因素；(3)研究了不同城市污泥堆肥处理对蜈蚣草根际土壤微生物群落多样性的影响，结果表明城市污泥堆肥处理改变了蜈蚣草根际土壤微生物种群丰度，Pseudomonas属细菌和Sphingomonas属细菌对比对照分别提高了119.66%和11.49%，有效促进了蜈蚣草根际砷的活化能力和蜈蚣草的生长，说明还原性细菌属的增加是城市污泥堆肥提高根际土壤砷活性的重要机制；(4)研究了不同城市污泥堆肥处理对蜈蚣草吸收转运砷的影响，结果表明城市污泥堆肥提高了蜈蚣草羽叶三价砷含量的比例，提高了蜈蚣草体内抗氧化酶的活性，有效提高了蜈蚣草对砷的转运能力和富集能力。综上所述，蜈蚣草联合城市污泥堆肥的模式对修复砷污染土壤具有较好的应用前景。