滇池沉积物中有机物和POPs分布特征及其来源示踪研究

Lakes play a significant part in carbon storage and fluxes through the land-ocean aquatic continuum. They also contain the extremely Soil organic matter not only is the principal part of terrestrial carbon pool and important index of soil quality, but also is carrier of organic pollutants and heavy metal. The organic matter and its carried organic pollutants in the sediment will different in the composition structure due to the different implement of land use, human activity intensity and soil erosion. Thus, the distribution characteristics and source of organic matter and its carried organic pollutants in the sediment will indicate human activity intensity and its influence to the ecological environment. In this study, Dianchi lake is selected as the study area. Based on the understanding of temporal-spatial distribution of organic matter and persistent organic pollutants (POPs) in sediments, sources and transformation mechanism are analyzed. 210Pb and 137Cs isotopic tracers techniques are used to record yearly changes and accumulation properties of organic matter and POPs in sediments. Using both n-alkane biomarkers and POPs fingerprint, impact of human activities on the yearly change and accumulation of sedimentary pollutants is studied. According to temporal-spatial distribution and sources of organic matter, OCPs and PAHs in the soils, water and sediments from Dianchi lake, evolutionary history and pattern of regional eco-environment of Dianchi watershed are constructed.

土壤有机质不仅是陆地碳库的主体、表征土壤质量的指标，而且是重金属、有机污染物的重要的载体。由于土地利用类型、人类活动强度以及土壤侵蚀作用的不同，使得土壤中的有机质及其负载污染物在沉积物中存在结构性差异。故沉积物中有机质及其负载污染物的分布特征及其来源有效地反应了该区域的人类活动及其对生态环境的影响。本研究选择滇池作为研究目标区，以沉积物中有机物以及POPs的时空分布特征为切入点，充分研究沉积物中有机物和POPs的来源及其示踪方法，并结合210Pb和137Cs沉积物定年技术，确定有机物和POPs在沉积物中年际变化规律和积累特征；联合使用正构烷烃和POPs指纹特征研究人类活动对沉积物中污染物年际变化规律和积累量的影响。根据土壤、水体和沉积物中有机物和POPs分布和来源的时间变化规律，最终反演滇池流域的区域生态环境演变历史和规律。

由于土地利用类型、人类活动强度以及土壤侵蚀作用的不同，使得土壤中的有机质及其负载污染物在沉积物中存在结构性差异。故沉积物中有机质及其负载污染物的分布特征及其来源有效地反应了该区域的人类活动及其对生态环境的影响。通过本项目的资助，基本探明了滇池流域不同土地利用类型土壤中有机碳的结构特征，以及正构烷烃（n-alkanes）和多环芳烃（PAHs）的构成差异；DOC和CDOM的光谱特征结果表明滇池北部地区表层沉积物中DOM的芳香性、分子量和腐殖化程度均大于中部和南部地区；滇池沉积物中多环芳烃的主要来源分别占比为：交通排放（30.5%）>汽柴油燃烧（25.1%）>岩石形成（23.1%）>煤碳燃烧（21.3%）。滇池沉积柱(ΣPAH16)分布范围为172-2245 ng g-1。滇池沉积柱由北到南多环芳烃浓度呈下降趋势。人口、GDP和能源消费量是各沉积柱中ΣPAH16含量的主要影响因素，而在表层沉积物中，由于政府环保政策的实施，能源结构的调整，即使人口、GDP和能源消费量继续增长，但ΣPAH16含量却呈下降趋势。该项目明确了人类活动对滇池沉积物有机质和PAHs来源量的影响，为滇池流域的区域生态环境演变历史和规律研究提供了坚实的数据基础。