| 题名 | 青藏高原湖泊沉积物中多环芳烃和有机氯农药的沉积记录 |
| 作者 | 谢婷 |
| 学位类别 | 硕士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 杨瑞强 |
| 关键词 | 多环芳烃（PAHs） 有机氯农药（OCPs） 青藏高原 湖泊沉积物 高山湖泊 polycyclic aromatic hydrocarbons (PAHs) organochlorine pesticides (OCPs) Tibetan Plateau lake sediment alpine lake |
| 其他题名 | Sedimentary Records of Polycyclic Aromatic Hydrocarbons (PAHs) and Organochlorine Pesticides (OCPs) in Lake Sediments from the Tibetan Plateau |
| 学位专业 | 环境科学 |
| 中文摘要 | 近年来，有关持久性有机污染物（persistent organic pollutants-POPs）环境行为的研究成为环境科学领域的热点问题之一。POPs具有大气长距离传输的特性，能够通过“全球分馏效应”以及“山地冷凝结效应”富集到偏远地区，对生态系统较脆弱的高山与极地地区带来威胁。通过研究高山地区环境介质中POPs的浓度水平、空间分布以及时间变化等规律，可以了解POPs在全球和区域尺度的迁移转化行为，为生态系统的风险评价提供数据支持。青藏高原作为“亚洲水塔”，为全球近半数的人口提供水源，其位于亚欧大陆人口最密集、工农业迅速发展的区域，加上印度季风的显著影响，使其成为污染物的潜在的“汇”。 湖泊沉积物是常用来研究偏远地区污染物沉降历史的重要环境介质。通常情况下，偏远高山湖泊受到人为干扰相对较小，其湖芯能很好地记录大气污染物的沉降信息，结合现代先进的样品定年技术，已被成功应用于研究污染物的沉降历史和演变规律。本研究通过分析青藏高原不同区域湖泊沉积物样品中两类典型POPs的时空分布特征，重现污染物的大气沉降历史，探讨其主要影响因素及来源，并对水体中污染物的生态风险水平进行评估。另外，为了探讨地表径流对湖泊沉积物中POPs浓度与组成分布的可能影响，本研究还初步研究了湖泊流域土壤与牧草中POPs的污染特征及可能存在的生物富集效应。本文共分为以下5章： 第一章对POPs的定义、性质及长距离传输行为进行了概述，综述了有关全球偏远高山湖泊沉积物中POPs污染的研究，并提出本文的研究内容及意义。 第二章通过分析青藏高原5个湖泊沉积物中PAHs的浓度特征，得出5个湖泊表层沉积物中Σ16PAHs的浓度范围为221~579 ng·g-1，与青海湖以及智利安第斯山脉的研究结果相似，但高于南极沉积物PAHs浓度，总体处于较低或中等污染水平。PAHs单体主要以分子量较小的2环&3环为主，占总浓度的80%以上，符合分子量较小的化合物更容易随大气进行长距离传输的规律。不同湖泊沉积物中PAHs的垂直分布的差异主要体现在浓度水平和增长趋势上，但总体而言每个湖泊沉积物中PAHs的Flux均在20世纪50~70年代间出现显著且持续的增长趋势，且之后增长更为迅速。一定程度上反映了我国及周边国家在过去几十年里持续增长的人类活动。 第三章讨论了青藏高原5个湖泊沉积物中OCPs的污染特征。5个湖泊表层沉积物中HCB、Σ4HCHs和Σ6DDTs的浓度范围分别为0.28~1.09 ng·g-1，0.69~1.37 ng·g-1和0.28~1.04 ng·g-1，浓度水平比北极和南极的相关报道高，与南美洲以及喜马拉雅南坡的浓度水平相当。OCPs的垂直分布波动较小，但在错那湖和可鲁克湖中，DDTs在20世纪70~80年代间出现显著峰值，与我国及周边国家DDTs的使用峰值时间一致。OCPs与OM间无显著相关关系，说明有机质不是控制OCPs分布的主导因素。相关性分析表明HCHs和DDTs间有较好的相关性，PAHs与HCHs显著相关。 第四章利用特征单体比值法探讨了湖泊沉积物中PAHs和OCPs的可能来源，结果表明PAHs主要产生自生物质和化石燃料的燃烧过程，而较低的α-/γ-HCH和o,p′-/p,p′-DDT比值，反映了近年来林丹与三氯杀螨醇在中国以及周边国家的大量使用。反向气团模型的模拟结果显示，青藏高原南部和中部主要受印度季风和西风带南支影响，而北部区域受印度季风影响较小，主要受到西风带北支及中国内陆气团影响。通过TEQs生态风险评估，得出本研究区域沉积物中POPs的生态风险水平较低。 第五章为了初步探讨地表径流对湖泊沉积物中污染物的来源贡献，分析了青藏高原中部与北部六个典型湖泊流域的土壤与牧草样品中多环芳烃和有机氯农药（包括六六六和滴滴涕）的污染水平。土壤样品中Σ16PAHs、ΣHCHs和ΣDDTs的平均浓度分别为194 ng·g-1，0.31 ng·g-1和0.07 ng·g-1。牧草样品中Σ15PAHs（不包括萘）、ΣHCHs和ΣDDTs的平均浓度分别为327 ng·g-1，2.17 ng·g-1和0.92 ng·g-1，均远低于欧洲高山中相应介质中POPs的浓度。牧草的生物浓缩效应显著，其生物浓缩因子达到4.2~19.3。POPs的浓度分布与有机质/脂肪含量、海拔均无显著相关关系。通过对比土壤、牧草及相应湖泊沉积物中POPs的浓度水平，发现土壤中POPs浓度显著低于沉积物，而沉积物中POPs浓度同样显著低于牧草，进一步反映了牧草对POPs的生物富集作用。 最后对全文进行了总结，并对未来的研究工作作出展望。 |
| 英文摘要 | The behavior and fate of persistent organic pollutants (POPs) in mountain regions have attracted increasing attention in recent years. POPs can be transported to remote areas such as high mountains and polar regions, exhibiting “global distillation effect” and “mountain cold-trapping effect” and subsequently pose great risks to these fragile ecosystems. Studies on spatial-temporal distribution patterns of POPs in environmental matrices from high mountains can shed light on our understandings about environmental fate of POPs, and support fundamental data to evaluate their ecological risks. The Tibetan Plateau (TP), as “water towers of Asia”, provides water supply for nearly half the world‟s population and is surrounded by the most densely populated countries with intensive industry and agriculture, which makes it a potential sink of pollutants. Sediment is an important matrix to reconstruct input history of pollutants in remote areas. Generally, lakes from high mountains are scarcely affected by direct anthropogenic activities, which makes sediments there can well preserve deposition information of POPs. Combined with advanced dating technologies, sediments have been widely and successfully applied to study deposition history and environmental fate of POPs. This study was aimed to analyze spatial-temporal distribution patterns of POPs in sediments from different lakes in TP and then to investigate possible influential factors. Potential sources of POPs were also discussed, while ecological risks of POPs in sediments were evaluated. Finally, the distribution patterns of POPs in soils and grasses collected from lake catchments were studied in order to investigate influence of runoff on lakes and to understand potential bioaccumulation effects. The following 5 chapters were included in this study: 1. This chapter introduced definition and properties of POPs, as well as long -range atmospheric transport theory. Study progresses about POPs in sediments from remote high mountains were reviewed, followed by the motivation and objects of this study. 2. Distribution patterns of polycyclic aromatic hydrocarbons (PAHs) in sediments from five lakes were discussed in this chapter. The surface concentration range of Σ16PAHs was 221-579 ng·g-1, which was similar to the results from Qinghai lake and Andean Mountain, but higher than those from the Antarctica. PAHs were dominated by 2&3-ring homologues with the percentage larger than 80%, which indicated that homologues with smaller molecular weight were relatively easier to be transported to remote areas. Vertical distribution of PAHs in sediments from different lakes differed in the concentration level and increasing trend. As a whole, 5 lakes shared the common feature that Flux of PAHs showed substantial and continuous growth trend during the 1950s-1970s, which reflected the rapid development in economics in surrounding countries during the past few decades. Sedimentation rate was the key factor influencing pollutant inventory and correlations of organic matter (OM) with PAHs depended on regional fuel combustion trait. 3. In this chapter, pollution patterns of organochlorine pesticides (OCPs) in sediments were analyzed. The surface concentrations of HCB, Σ4HCHs and Σ6DDTs were in the range 0.28-1.09 ng·g-1, 0.69~1.37 ng·g-1 and 0.28~1.04 ng·g-1, respectively. The concentration level of OCPs in this study was higher than the Arctic and the Antarctica, and similar to those from South America and southern slope of Himalaya. The vertical profiles of OCPs in sediments were “stable” without large fluctuation. However, DDTs in sediments from Cuo Na and Keluke showed apparent concentration peak during the 1970s-1980s, which was accordant with the numerous applications of DDTs in that period in China and surrounding countries. OCPs were not significantly correlated with OM, which indicated that OM was not the dominate factor influencing the distribution of OCPs in sediments. HCHs and DDTs were well correlated with each other, while PAHs were only correlated with HCHs. 4. Diagnostic ratios of PAHs indicated that biomass and fossil fuel combustions were the major sources for PAHs. The relative low values of α-/γ-HCH and o,p′-/p,p′-DDT provided evidences for present numerous usage of lindane and dicofol. Our results of backward airmass trajectory models indicated that the southern and central TP were mainly affected by the Indian monsoon and the southern branch of the westerly wind. The northern TP was mostly influenced by airmass from inland China and the northern branch of the westerly wind. Sediment quality guidelines were introduced to assess sediment quality, and the results indicated that POPs in sediments from the TP can be ranked as low potential ecological risk. 5. To evaluate the contribution of runoff to lakes, soil and grass samples were collected from 6 typical lake catchments in the central and northern TP and analyzed for PAHs and OCPs (including HCHs and DDTs). The average concentrations of Σ16PAHs, ΣHCHs and ΣDDTs in soil samples were 194 ng·g-1, 0.31 ng·g-1 and 0.07 ng·g-1, while those of Σ15PAHs (excluding NAP), ΣHCHs and ΣDDTs in grasses were 327 ng·g-1, 2.17 ng·g-1 and 0.92 ng·g-1, respectively. All compounds were significantly lower than those in European high mountains. The biological concentration effect of grasses to soils was notable with the values of biological concentration factor (BCF) ranging from 4.2 to 19.3. No significant correlations were observed between concentrations of POPs and content of OM/lipid, or altitude of the sampling sites. POPs in soils were found to be significantly lower than those in sediments and this might be caused by erosion process of runoff. POPs in sediments were also much lower than those in grasses, which further confirmed the notable bioaccumulation effect of plants. Finally, the key points of this study were summarized and prospects for future research about POPs in remote areas were also proposed. |
| 公开日期 | 2015-07-08 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/15713]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 谢婷. 青藏高原湖泊沉积物中多环芳烃和有机氯农药的沉积记录[D]. 北京. 中国科学院研究生院. 2014. |
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