邻苯二甲酸酯类增塑剂在土壤中的化学转化机制研究

Phthalate esters plasticizers belong to a group of environmental contaminants with endocrine properties. Their use has been banned or constrained in toys and child products internationally. They were widely detected in China's agricultural and urban soils with concentrations tens to hundreds of times higher than European and US soils. Most previous research on the environmental fate of phthalate ester plasticizers focused on their biodegradation and removal during wastewater treatment. Limited information is available about their transport and transformation in soil. We propose to investigate processes influencing the fate of selected plasticizers in soil environments. The plasticizers to be investigated include three phthalate esters differing in the length and branches of side chains, (di-n-butyl phthalate, di-iso-butyl phthalate and bis(2-ethylhexyl) phthalate) and the environmental friendly plasticizer acetyl tributyl citrate. We propose to study their adsorption to/desorption from specific soil components as a function of solution chemistry (e.g., pH, ionic strength, exchangable cation); explor reaction kinetics and mechanisms with model humic and fulvic constituents as influenced by catalase or solid phase oxidants present in soils (MnO2), which may have an effect on incorprating phthalate easter into soil organic matter; examine reactions between alfalfa root exudate and plasticizers in soil; evaluate the possible structures of reaction products based on density functional calculation and the associated reaction pathways using the Gaussian03 software package. The research will be conducted with state-of-the-art experiment techniques and instruments including HPLC-UV or MS/MS, GC-FID/MS, and UV-Vis, ATR-FTIR, and NMR spectroscopy. The results of the proposed project will provide insight into the distribution and degradation of these plasticizers in soils and will inform efforts to remediate plasticizers in soils.

邻苯二甲酸酯类化合物是一类具有环境激素性质的增塑剂，目前在我国的工业发达地区以及设施农业土壤中含量较大,已经对人们的身体健康和环境安全产生威胁。虽然许多研究关注这些化合物的生物降解和废水处理方法，但对它们的土壤环境行为研究非常有限。本项研究选择三种具有不同侧链长度和支链的邻苯二甲酸酯以及一种环境友好型增塑剂乙酰柠檬酸三丁酯，通过现代色谱仪器和微观光谱手段，系统研究它们和土壤黏土矿物间的吸附-解吸作用、与腐殖酸和富里酸模型分子间的交联反应、与植物根系分泌物中的生物活性分子间的交联或降解反应；利用量子化学计算(密度泛函理论,Gaussian03 软件)计算探索邻苯二甲酸酯类增塑剂在土壤中的化学转化机制；并研究邻苯二甲酸酯及其化学转化产物对土壤微生物(以大肠杆菌和固氮菌为指标生物)的生长影响。本项研究的结果将有助于评价和针对性的修复我国比较严重的邻苯二甲酸酯增塑剂的土壤污染。

邻苯二甲酸酯类化合物是一类具有环境激素性质的增塑剂，目前在我国的工业发达地区以及设施农业土壤中含量较大,已经对人们的身体健康和环境安全产生威胁。虽然许多研究关注这些化合物的生物降解和废水处理方法，但对它们的土壤环境行为研究非常有限。本项研究以邻苯二甲酸酯为研究对象，通过现代色谱仪器和微观光谱手段，系统研究它们和土壤黏土矿物、铁氧化合物、土壤有机质间的吸附-解吸作用、氧化还原，以及小分子有机酸等对这些反应的影响；利用量子化学计算(密度泛函理论,Gaussian03 软件)计算探索邻苯二甲酸酯类增塑剂与小分子有机酸的化学转化机制；并研究邻苯二甲酸酯及其化学转化产物对土壤微生物的生长影响，生物堆肥对邻苯二甲酸酯在土壤中迁移降解的作用。研究表明，土壤粘土对小分子的邻苯二甲酸二乙酯有很好的吸附性，粘土结构中的铁在氧气和小分子多酚的作用下能有效的降解这类分子；铁氧化合物不仅在暗反应条件下对这类分子有降解作用，在光照情况下的柠檬酸能促进降解，铁氧化合物的晶格作用对产生的羟基自由基的影响很大；蘑菇堆肥对邻苯二甲酸酯有很好的吸附作用,但是它的降解作用不大。土壤微生物对邻苯二甲酸酯二异戊酯的降解途径主要是邻苯二甲酸途径。本项目的研究对邻苯二甲酸酯在土壤中的迁移转化有一个清晰的了解，为下一步治理该污染物提供了策略和思路。.本项目共培养4名研究生和一名博士后，已发表6篇SCI文章和1篇中文核心文章，较为成功的完成了项目设定的目标，并为下一个项目提供了科研基础。