罗勒等芳香植物对土壤多环芳烃的吸收积累和代谢机理研究

Polycyclic aromatic hydrocarbons (PAHs) are one kind of persistent organic pollutants of importance which cause extensive environmental concern. Phytoremediation is a hot topic of soil PAHs remediation. Previous phytoremediation research with crops as dominant remediation plants failed to fulfill eco-security, sustainability and aesthetics. Additionally, it remains unclear concerning the metabolic mechanisms of PAH detoxification. Therefore, in this research, aromatic plant represented by basil, vetiver and lemon grass which are used majorly for landscaping and essential oil production will be selected as candidates to investigate the uptake, accumulation and metabolic pathways of PAHs by aromatic plants. Hydroponics and soil pot experiments combined with chromatography-spectrometry analytical techniques will be employed to disclose the applicability and mechanisms of aromatic plant-assisted remediation. Given that basil etc. are rich in lipid-soluble secondary metabolites; while lipid content is a key plant trait accounting for PAH uptake and accumulation, the research will also investigate the influence of soil PAHs on essential oils, as well as the dynamic distribution of PAHs in plant lipid-water phase, with the aim to discover the effects of lipid-soluble secondary metabolites on plant uptake, accumulation and metabolism of soil PAHs. This research will provide scientific proofs for an effective, safe and sustainable application of phytoremediation techniques.

多环芳烃（polycyclic aromatic hydrocarbons，PAHs）是环境中受广泛关注的一类重要持久性有机污染物。植物修复是PAHs污染土壤修复的热点。以往以农作物为主要修复植物的研究达不到安全、可持续和景观美学的效果，有关植物代谢PAHs脱毒的机理也不完全清楚。 因此，本项目以景观绿化和精油生产两用的芳香植物罗勒、香根草、柠檬草为修复植物，采用水培和土壤盆栽实验，结合色谱质谱分析技术研究罗勒等植物对土壤PAHs的吸收积累和代谢路径，以揭示其修复PAHs污染土壤的适应性和机理。鉴于罗勒等芳香植物脂溶性次生代谢产物含量较高，而脂肪含量是影响PAHs吸收积累的最重要植物生物特性，本项目亦研究了PAHs对植物精油的影响及PAHs在植物脂相和水相之间的动态分配，以进一步阐明脂溶性次生代谢产物对PAHs吸收积累和代谢的影响。本研究为植物修复技术的有效、安全、可持续实施提供理论依据。

多环芳烃（polycyclic aromatic hydrocarbons，PAHs）是环境领域受广泛关注的一类持久性有机污染物。环境中绝大多数的PAHs汇集到土壤中，对人类健康造成潜在威胁。植物修复是PAHs污染土壤修复的前沿。不同于以往以作物为植物修复载体的研究，本项目选用油用和观赏两用的芳香植物罗勒为修复植物代表，以16种PAHs为目标污染物，以工业区一PAHs污染严重的实地土壤为修复样本开展盆栽实验，利用GC-MS分析土壤中16种PAHs的动态变化及PAHs在植物体内的生物积累，并研究了PAHs污染对植物次生代谢产物的影响，结果发现植物种植105d后可去除～14.4%的土壤Σ16PAHs，土壤中低环PAHs优先被去除，使高环PAHs在土壤中累积逐渐增加。植物通过根系吸收对土壤PAHs去除率的贡献率不足2%，可见土壤PAHs的去除绝大部分归功于根际微生物降解。此外，PAHs污染对植物生长及植物挥发性次生代谢产物的产量和质量并未产生明显影响。菲和植物的水培实验结合GC-MS和UPLC-UV-QTOF-MS分析，结果表明菲在植物体内首先被氧化成水溶性强的酸和酯类，这些中间产物接着跟糖苷类物质轭合形成水溶性更强的无毒性污染物或者形成聚合物贮存在细胞中。本研究结果说明罗勒对PAHs污染土壤具有较强的适用性，今后可将罗勒等芳香植物应用到联合修复体系中强化脱污性能。