生物碳与天然有机质对疏水性有机污染物吸附和生物有效性的作用机制

Soil and sediment organic matter (SOM) is the main carrier of hydrophobic organic pollutants (HOCs) in the environment. However, due to highly complexity of SOM, the molecular-level mechanism governing HOCs in soil/sediments were poorly known. Furthermore, biochars, as one kind of exogenous organic matter, will affect the environmental behavior of HOCs in the soils and sediments at large-scale. Owing to the large difference in the raw materials and methods of producing biochars, the characteristics of biochars and the effect on the environmental behavior of HOCs is still lack of understanding. This project aims to reveal the contaminantion of biochars and the effectiveness of on the bioavailability of HOCs with the help of the laboratory experiment and simulation; to explore the difference in sorption behavior between different organic fractions or kinds of biochars to phthalic acid ester (PAEs) and reason to be responsible for these differences. Using combination organic geochemical theory with modern technology including nuclear magnetic resonance (NMR), X-ray photoelectron spectra (XPS), scanning electronic microscope (SEM),X-ray absorption near edge fine strture (NEXAFS), ultra high vacuum scanning tunneling microscopes (UHV-STM), etc. to investigate the mechanism of influence of the different funcitonal groups associated with biochars and natural organic matter on their HOCs sorpiton; to shed a new insight into the sorption sites and sorbed forces between HOCs and sorbents at the coexistence of organic matter and minerals; to determine the influence of the interaction between organic matter and minerals on the sorption and bioavailability of HOCs. This program helps to understand the microscope-mechanism of interactions between HOCs and geosorbents from the perspective of particles-molecular levels and to evaluate objectively the transfer and fate of HOCs in the surface environment as well as to provide reliable scientific basis for the sustainable application in improving soil quality and remediation of water systems and establish management measures of prevention and control of HOCs in the environment.

土壤与沉积物的有机质是疏水性有机污染物（HOCs）的主要环境载体，因有机质的高度复杂性，其吸附HOCs微观机理尚待深入研究。而作为一种土壤和沉积物的外源有机质，生物碳应用后也势必影响土壤与沉积物中有机污染物的环境行为。本项目通过实验室分析和模拟实验揭示不同类型生物碳对HOCs吸附和有效性的影响；明确不同形式有机质和不同类型生物碳对新兴污染物邻苯二甲酸酯（PAEs）的吸附行为；将有机地球化学理论与现代光谱、能谱、显微和核磁共振等技术手段相结合，探讨生物碳和天然有机质中不同官能团对HOCs吸附和有效性影响的不同机制；探析有机质吸附HOCs的吸附位点和吸附作用力;确定有机质与无机矿物的相互作用对HOCs的吸附和有效性有无影响。该项目从颗粒到分子尺度上研究HOCs-环境介质相互作用的微观机制。为生物碳的应用、制定土壤和水体中HOCs的防控和治理措施等方面提供可靠的科学依据。

本项目研究了不同形式有机质和不同类型生物炭对新兴污染物邻苯二甲酸酯（PAEs）的吸附行为；解析了生物炭（biochar）和天然有机质中不同官能团对HOCs吸附不同机制及矿物存在条件下对其吸附的影响；研究了生物炭中金属和断环芳烃污染物（PAHs）的污染水平。研究结果发现SOM组分的热稳定性和生物地球化学稳定性之间可能存在潜在联系，SOM组分的组成对稳定性的影响可能与碳的来源和SOM分解程度有关；芳香碳组分不一定主导菲（PHE）的吸附，有机质组分的整体或表面极性在的吸附中所起的作用与土壤来源有关；在SOM中，除非水解有机碳（NHC）外，其他SOM组分对PAEs的吸附主要是由于疏水作用和氢键绑定作用;揭示了纳米孔填充机制在天然有机质（NOM）和biochar对菲的吸附过程中占主导地位，NOM的脂肪碳和biochar中芳香碳分别控制他们对HOCs的吸附，证明了SOM的结构和微孔特性对菲吸附的影响与SOM的来源有关； 生物炭含有的丰富的矿物，有利于和有机质相连的极性官能团在生物炭表面的暴露。菲在生物炭上的有机质标化分配系数（KOC）大体上呈增加趋势，归因于去矿后疏水性吸附位点的增加；水热解生物炭的拉曼光谱和13C核磁共振表明，水热解生物炭中存在无定型态有机碳，这解释了其对极性和非极性HOCs具有较高的吸附能力的现象，水热解生物炭中无定型的脂肪碳和芳香碳共同支配着其对HOCs的高吸附能力；生物炭中的金属/类金属元素的含量和成分主要受原材料的影响，而热处理温度（HTTs）作用较小。另一方面，原材料是影响生物炭中PAHs的成分的重要因素，但对∑PAHs含量影响较小，而HTTs显著影响生物炭中PAHs的成分、含量及毒性水平。该项目从颗粒到分子尺度上研究HOCs-环境介质相互作用的微观机制。为生物炭的应用、制定土壤和沉积物水体中HOCs的防控和治理措施等方面提供可靠的科学依据。