中纬度地区气候环境变化对持久性有机污染物归趋行为的影响-以神农架大九湖为例

Persistent organic pollutants (POPs) are lipophilic, hydrophobic, and semi-volatile chemicals. They are degraded slowly in natural condition and can affect human health by bio-accumulation and toxicity. Soil, sediment and ice glaciers are generally sinks for POPs due to higher deposition than volatility in those media. However, those POPs maybe released from those media to environment as “time bomb” if the climate warm occurred or by human activity. This project aims to study the impact of climate and environment change on the transfer and fate behaviors of typical POPs (e.g. PAHs and OCPs) in the mid-latitude region. We will take Dajiuhu Peat Wetland in Shennongjia as the case study. The age of sediment core will be dated by isotope method. The climate and environment when sediment formed will be inferred. The sediment velocity, input fluxes and main sources and contribution to POPs will be investigated. The quantitative relation will be established after filed monitoring and laboratory modelling. Finally, the prediction and evaluation on impact of the transfer and fate of POPs on environment will be carried out according to climatic and environmental change in the future. The diagnosis of source and sink, transfer process traced for POPs in hundred-year time scale will help us to completely understand the environmental geochemistry behavior and pattern of POPs in subalpine in mid-latitude region. The research would be of important theoretical significance in POPs’ global immigration and transfer in special topographic region . It also has practical significance in ecological environment protection and to assure water safety in water source area.

持久性有机污染（POPs）具有半挥发性、难以降解性、毒害性及生物积累性，土壤、沉积物和冰川往往是POPs在环境中的最终归宿。但是受气候变暖和人类活动影响，贮存在这些介质中的POPs会被二次释放重新回到环境中，成为“定时炸弹”。本项目拟开展中纬度地区——神农架大九湖为例，气候环境变化对OCPs和PAHs归趋行为影响的研究。对大九湖泥炭柱的形成年代、气候环境及POPs的沉积速率、迁移通量、主要来源及贡献量、源汇转换等进行探讨，通过野外监测与室内模拟相结合方法，建立气候环境变化与POPs环境行为的定量响应关系，进行气候环境变化对POPs归趋的预测和评价。通过对百年尺度内POPs源汇角色识别与转换过程追踪，全面把握中纬度亚高山POPs环境地球化学过程与规律。这一研究可以丰富POPs全球迁移理论，加深对POPs在特殊地貌单元归趋的理解，还具有保护生态环境和水源地水质安全的现实意义。

持久性有机污染物（POPs）是具有高毒性、持久性、生物累积性和半挥发性的有机污染物，并可以通过食物链的放大效应在动物以及人体中富集。项目以大九湖泥炭地泥炭岩芯为研究载体，围绕百年尺度内持久性有机污染物的沉积记录结合黑炭（BC）及有机碳（TOC）等指标，揭示百年尺度内人为活动对大九湖泥炭地沉积的影响，并结合室内模拟实验，建立环境和气候变化对于泥炭柱中持久性有机污染物源/汇影响。.结果表明：泥炭岩芯中粒度分布主要以粉沙为主，粒度及TOC和BC可以很好的记录典型的环境气候变化特征，尤其是粒度分布可以很好的显示大九湖地区冷、暖及干旱事件变化。Σ16PAHs的浓度范围为212.67 ~ 830.10 ng·g-1, BC的浓度范围为7.89% ~ 36.48%。主要成分Phe占Σ16PAHs的36.83%±4.53%。PAHs同系物分子诊断表明，大气长距离迁移是大九湖地区PAHs主要来源，而热源主要为生物质、煤和石油燃烧，高含量Phe指示植物来源可能是2000年前Phe的主要贡献源。社会经济活动指标表明，煤炭和石油消耗量以及机动车数量对4-、5-和6-环PAHs有很大影响。年沉积通量变化范围较大，介于13.58~276.44 ng·cm-2·a-1之间，沉积速率对其影响较大。.大九湖年平均气温、年降水量与泥炭中16种PAHs含量具有明显负相关关系，泥炭柱温度模拟实验定量探究表明，随温度上升，泥炭样品中16种PAHs含量明显下降。温度与大九湖湿地泥炭PAHs含量的线性回归方程斜率K值为：-28.61至-31.58，不同深度泥炭样品中PAHs含量与温度间的定量关系稍有不同。可能是不同深度泥炭样品中TOC含量不同，泥炭样品本身对PAHs的吸附效应不同所致，而温度对于低分子量（2-3环）PAHs的赋存影响较大。.泥炭淋滤实验，淋滤过程对泥炭PAHs含量影响显著，淋滤水量与泥炭PAHs含量呈明显的负相关关系。进一步定量分析发现，降水量与PAHs含量的线性回归方程斜率K值范围为：-0.34至-0.24，定量变化关系的差异，可能是由于不同深度泥炭中PAHs组成差异，受到降水影响的途径不同所致。.本次研究证实了，大九湖泥炭柱是记录人类社会活动及气候环境变化的良好载体，摸清了泥炭柱中PAHs及BC、TOC的百年尺度内的沉积记录，并探讨了沉积记录对环境以及气候变化的响应，探讨了人为活动和气候变化