基于原位暴露对生物有效性动态变化与分子标志物响应机制的研究

Because of the complexity of physicochemical and geomorphological characterization in heterogeneous sediments, the chemical speciation and mobility of metals at the sediment-water interface are in non steady state and even in dynamic conditions, which resulted in high variability of contaminant bioavailability. Based on traditional point sampling for chemical analyses alone, laboratory toxicity tests or field surveys of resident biota, sediment contamination characteristics and risk assessments had disadvantages of inaccuracy, scientifically representing a worst case scenario in terms of complex exposure dynamics and their internal limitations of these techniques. In this proposal, through powerful experimental designs and field-based manipulations of aquatic in situ exposure and the monitoring methods of kinetic DGT approach, relevant scientific issues were explored regarding sedimentary metals in polluted coast influenced by industrialization and urbanization. Understanding the degree of pollution and geochemical characteristics of the entire sediment matrix in the selected sampling sites, the devised in situ testing chambers were simultaneously exposed under field conditions in deployment sites combining the DGT and benthic organism clam Ruditapes philippinarum as the bioindicator species, the dynamic exchanges,translocation and mobilization of metals were then clarified among the "particles, pore water, exposed organism" interface of sediments through measuring relevant dynamic parameters and resultant induced fluxes of metals during experimental procedures. Integrating the measurement of a wide battery of biomarkers based on the relevance of biological endpoint and our mechanistic knowledge, dynamic changing process of metal bioavailability in sediments were assessed, then their interactions with toxic effects were established between exposure and effects. Furthermore, variations of transcript expression of functuional genes in the choice of contaminant-specific biomarkers were obtained through high throughput oligo-DNA Microarray and quantitative reverse transcription polymerase chain reaction (Q-RT-PCR) in order to elucidate the mechanistic understanding of biological responses of cellular and molecular biomarkers. Simultaneously, the approach of in-situ evaluation combining the kinetic DGT is proposing to be established considering the consistency of framework as protocols among sediment chemistry, contaminant bioavailability and adverse effects, which provide a robust tool to support more comprehensive processes of sediment risk assessment, thus significantly improve accuracy and ecological relevancy in complex exposure situation when extrapolating the sediment quality guidelines (SQGs).

由于介质的高度异质化与理化特征呈现因时因地的巨大差异，沉积物重金属的形态和迁移转换处于复杂的动态变化过程，传统瞬时采样与生物效应获取方法不能准确的确定生物有效性以及科学的评价污染特征与毒性风险。本项目以近岸海域沉积物重金属为研究对象，在弄清污染特征的基础上，研制集成具有现场动态富集采样功能的DGT与菲律宾蛤仔的试验装置并同时原位暴露于现场，测定相关参数与不同介质中通量的变化，明确重金属在固/液/生物体之间迁移变化，确定影响生物有效性的因素、程度与动态过程；通过高通量oligo-DNA Microarray与定量反转录PCR对重要功能基因的表达分析，理解暴露生物的毒理效应并阐明分子标志物的变化响应机制；同时在"沉积物暴露－生物有效性－毒性效应"一致性的原则下，建立原位评价方法与体系；研究成果可更好的为沉积物重金属污染的防治、修复、环境质量基准推导提供理论依据，并提高风险评价中的生态相关性。

伴随着社会经济的高速发展、工业化与城市化进程的不断推进，大量不同种类污染物进入水域，形成错综复杂的混合污染，危害生态环境和人类健康；传统瞬时采样与生物效应测定方法不能很好的明确污染物形态迁移转化的动态变化过程、以及未能准确的评价污染效应与毒性风险特征。本项目在对受工业化与城市化影响的研究区域（马銮湾）广泛采样调查的基础上，分析水体、沉积物、生态位生物等各种环境介质中不同结合态重金属的污染水平，并明晰其污染特征；同时开发集成具有现场动态富集采样功能的薄膜扩散梯度技术(DGT)与生物同步原位暴露的装置，测定“污染物-生物关键组织负荷-生物标志物活性”，确定影响生物有效性的因素、程度与动态过程以及与暴露生物毒理效应之间的变化响应关系；通过高通量转录组测序(RNA-seq)，分析暴露生物的特征表达谱，确定现场环境试验生物关键组织中与氧化损伤和解毒有关的特异性表达基因，并经qRT-PCR验证，鉴别出更具响应灵敏性与相关性的分子标志物；同时在“污染现场暴露-生物有效性-毒性效应”一致性的原则下，进行原位评价，以及通过金属硫蛋白(MT)阐明亚细胞水平内在的毒理效应机制；由完成项目研究计划而获得的研究成果可为环境质量基准推导与环境效应监测提供科学指导与理论依据，并提高污染物环境风险评价中的生态相关性。研究内容已发表论文6篇，其中SCI引源期刊论文5篇，另有2篇论文目前审稿中。培养博士研究生1名、硕士研究生3名、联合培养硕士研究生1名。项目负责人就本项目研究内容，多次应邀在国内外学术会议上做报告以及主持会议Session，在国内外环境化学与生态毒理领域产生了广泛影响。