溶解性有机质结合的有机污染物对生物富集量增强效应及传质动力学过程的影响机制研究

In environmental aquatic system, dissolved organic matter (DOM) is a large group of compounds that have complex chemical structures and multiple interactions with their surrounding materials. It can interact with hydrophobic organic compounds (HOCs) and influence the environmental behavior of HOCs including bioaccumulation. Commonly, DOM binds with HOCs, and decreases the freely dissolved concentration and the bioavailability of the compounds. However, research also found that the bound compounds can not only increase the bioaccumulation amount but also affect the accumulation rate. Nowadays, due to the limitation of the experimental set-up and lack of theoretical models, no detailed research investigates the effects of bound compounds on the bioaccumulation process. In light of that, the current project aims to systematically investigate the effect of bound compounds on the bioaccumulation parameters especially the enhanced bioaccumulation amount and the accumulation rate. The research work will include the following parts. First, a standard solution generation system will be developed to prepare a micro-ecological simulation system, which will be used for all the exposure experiments. Second, two organism including daphnia magna and brocade carp will be selected as the model organism, and the bioaccumulation uptake kinetic curves in different exposure conditions will be conducted to obtain the bioaccumulation factor (BAF) and uptake rate constant. Third, the effect of the bound compounds on the bioaccumulation process will be elucidated by comparing the bioaccumulation parameters obtained from different matrices. Fourth, a prediction model will be developed based on the bioaccumulation parameters and the chemistry properties of the organic pollutants and the DOM. The importance of the proposed research work will be significant for investigating the environmental behavior of the organic contaminants, and provide the data to evaluate the environmental risk of the contaminants.

溶解性有机质（DOM）与疏水性有机污染物（HOCs）相互作用，改变了HOCs的赋存状态，使得一部分HOCs以结合态形式存在。以往研究认为，结合态HOCs的存在降低了游离态HOCs的浓度，从而降低了生物可利用性，减少了生物富集量。然而现有研究发现结合态HOCs也能参与生物富集过程，不仅增加生物富集量，且对富集速率产生不可忽略的影响。目前文献上关于结合态HOCs对生物富集过程，特别是生物富集量增强效应和富集传质动力学过程的影响多只报道了表观现象，未能阐明其影响机制。鉴于此，本项目拟采用标准溶液产生装置，建立模拟微生态系统；以大型溞和锦鲤为模式生物，系统研究DOM结合的HOCs对生物富集量和富集传质动力学过程的影响机制；进而构建含DOM水体中生物累积系数和富集速率常数预测模型。本项目对于阐明HOCs在生态系统内的迁移转化规律，更准确预测DOM对其生态毒性的影响具有重要的理论价值和实际意义。

环境水体中复杂基质与疏水性有机污染物（HOCs）相互作用，改变了HOCs的赋存状态，进而影响其迁移转化包括生物富集过程。以往研究认为，结合态HOCs降低了游离态HOCs的浓度，从而降低其生物可利用性，减少了生物富集量。也有研究发现结合态HOCs也能参与生物富集过程，不仅增加生物富集量，且对富集速率产生不可忽略的影响。目前文献上关于结合态HOCs对生物富集过程，特别是生物富集量增强效应和富集传质动力学过程的影响多只报道了表观现象，未能阐明其影响机制。鉴于此，本项目系统深入研究环境水体中复杂基质，包括溶解性有机质（DOM）和微纳米塑料对多氯联苯（PCBs）和多环芳烃（PAHs）在大型溞和罗非鱼体内富集过程的影响机理。获得的重要结果包括：.a. 采用被动加标法建立瓶式和箱式模拟微生态系统。用于两种不同大小的目标生物的暴露。该系统可产生游离态浓度恒定的水溶液，用于模拟生物暴露环境；此外，瓶式装置可用于测定有机污染物与复杂基质如DOM和微纳米塑料等的结合系数。.b. 采用构建的瓶式标准溶液产生装置，测定了11种PCBs和7种PAHs在不同尺寸聚苯乙烯微纳米塑料（100 nm, 500 nm, 1 μm, 2 μm）上的结合系数。同时，基于标准溶液产生装置，建立了一种方法，用于定量生物体内富集的纳米塑料的量。.c. 研究了带不同基团，不同尺寸微纳米塑料对大型溞和绿藻的毒性作用，并评估了DOM对其毒性的影响，提出微纳米塑料对两种生物的毒性作用机理。.d. 基于标准溶液产生装置，研究了微纳米塑料和DOM对PCBs和PAHs在大型溞体内富集过程影响，综合评估微纳米塑料与PCBs对大型溞联合毒性的作用；采用一个优化后的含有基质参数的生物动力学模型，估算PAHs通过不同途径的富集量，从而区分皮肤和肠道两个途径对生物富集过程的贡献。.本项目对于阐明HOCs在生态系统内的迁移转化规律，更准确预测环境复杂基质对其生态毒性的影响具有重要的理论价值和实际意义。