近两百年来黄土高原西部和沙漠黄土过渡带湖泊记录的十年/年际环境变化研究

The research of environmental changes and climate predictions today focuses on the hundreds of year climatic change and Human-environment relationship history of the Earth contained in various high resolutions environmental proxy records, which has become a significant problem to sustainable development. The western of Loess Plateau and desert/loess transition zone in northern China is very sensitive to Global Change. So, this area is good for the study of environmental changes and Human-environment relationship. In the project, the effort will be devoted to three aspects: Firstly, the chronology of several lake cores from the study area will be established based on the analysis of 210Pb and 137Cs distribution in cores, and in combination with multi-proxy records including modern seasonal pollen assemblages, grain-size and the lake age recorded by historical archives. Secondly, the history of plant community/ecology and climate change on annual-to-decadal timescale during the past 200 years in the spatial will be reconstructed by high-resolution (annual-to-decadal timescale) pollen assemblages, pollen influx, loss on ignition, particle size and sedimentation flux. Thirdly, based on the above and historical archives and instrumental data, we will understand the temporal and spatial variation of environment and human-environment relationship deeply and separate the natural fluctuations and human impact on the environmental change. This study will provide basic data and theory evidence for the impact of human activity on natural climatic change and the future environmental change, and provide scientific ground for the sustainable development and ecological restoration.

利用高分辨率环境代用指标的综合比对，研究近几百年短尺度气候变化和人地关系，是环境变化与预测研究的重点，对人类社会可持续发展具有更直接的意义。黄土高原西部和沙漠黄土过渡带的环境变化对全球变化响应极为敏感，是研究环境变化和人地关系的理想区域。本项目利用210Pb和137Cs测年、成湖记载、现代季节花粉等多种指标相互印证综合定年，建立该区系列湖泊岩芯的准确年代框架；通过对高分辨率(十年/年际)花粉组合、花粉通量、烧失量、粒度和沉积通量等多种环境代用指标的分析和综合比对，重建近200年来十年/年际分辨率的植物群落/生态和气候变化的时空序列；结合历史文献和器测气象资料，系统和深入地研究短尺度、高分辨率的环境和人地关系的时空变化特征，识别环境变化中的气候因素和人为因素。此研究可为认识人类活动对气候变化的影响和预测未来环境变化提供基础数据和理论依据，从而为人类社会可持续发展与生态恢复提供科学依据。

利用高分辨率环境代用指标的综合比对，研究近几百年短尺度气候变化和人地关系，是环境变化与预测研究的重点，对人类社会可持续发展具有更直接的意义。黄土高原西部和沙漠黄土过渡带的环境变化对全球变化响应极为敏感，是研究环境变化和人地关系的理想区域。本项目首先发明了一套湖芯采样装置，改进了烧失量实验技术方法，并确立了烧失量法适宜的实验条件组合，为野外湖芯取样和实验室分析奠定了良好的基础。其次通过不同季节现代沉积物和湖泊/岩芯沉积物的花粉和粒度分析，确定了年际/季节沉积层花粉特征，并建立了鉴定年际/季节沉积层的方法, 为高分辨率的(十年/年际)重建古环境提供了科学依据。初步认为，春季型花粉，如榆属、沙棘属、桦木属、栎属和松属-单束松型花粉的百分含量在的深色层中要高于浅色层，夏-秋季型花粉，如蒿属、蒲公英属花粉的百分含量在浅色层中要高于深色层；乔木花粉在深色层中含量较，草本花粉在浅色层含量较高；并且过去50年来（1958~2011年）浅色层厚度与夏季降水相关密切。然后建立高精度的年代序列，通过对湖芯沉积物高分辨率(十年/年际)的花粉、粒度和烧失量分析，重建环境变化的时空序列，结合历史文献和器测气象资料，系统和深入地研究短尺度、高分辨率的环境和人地关系的时空变化特征，识别环境变化中的气候因素和人为因素。此研究可为认识人类活动对气候变化的影响和预测未来环境变化提供基础数据和理论依据，从而为人类社会可持续发展与生态恢复提供科学依据。