On the basis of multi-proxy analysis on TOC, TN, C/N, organic δ^13C and grain size, sediment record from Qinghai Lake provides evidences of stepwise-pattemed climatic change since 16 ka BE Results show that Qinghai L...On the basis of multi-proxy analysis on TOC, TN, C/N, organic δ^13C and grain size, sediment record from Qinghai Lake provides evidences of stepwise-pattemed climatic change since 16 ka BE Results show that Qinghai Lake underwent six environmental stages. From 16.2 to 14.3 ka BP and from 4.0 to 2.1 ka BP, the organic δ^13C value was controlled by the concentration of atmospheric CO2. Relative higher organic δ^13C values occurred between 14.3 to 10.4 ka BP indicative of water hardness decrease resulted from melting ice water, corresponding to two intervals of C/N peak values to the Boling and AIlerod warm periods in Europe respectively. From 10.4 ka BP, Qinghai Lake entered the Holocene and the climate was warm and a little dry. The Megathermal appeared at about 6.7 ka BP when the vegetation around the lake transformed into a forest. Between 6.3 ka BP and 4.0 ka BP, the temperature decreased and δ^13C value was controlled by the expansion of C3 plants and the retreat of C4 plants in river catchment. Since 4.0 ka BP, the climate gradually became cold and dry. From 2.1 ka BP, the cold-dry climate and human activity resulted in an abrupt increase in C/N with deceased δ^13C value; meanwhile, many coarse grains appeared in sediments.展开更多
Based on careful sampling and accurate analysis of recent sediments in Lake Chenghai, this paper discusses the staggered positive/negative correlation between organic carbon (OC) concentration and inorganic carbon (IC...Based on careful sampling and accurate analysis of recent sediments in Lake Chenghai, this paper discusses the staggered positive/negative correlation between organic carbon (OC) concentration and inorganic carbon (IC) concentration. The result indicates that temperature change, and its induced relative changes are the main factors affecting the relationship between IC concentration, δ13C of carbonate and OC concentration. When temperature and its induced photosynthesis strength change control autochthonous calcite precipitation, OC concentration is positively correlated with IC concentration and δ13C of carbonate. When temperature and its induced physical/chemical changes dominate, OC concentration displays negative correlation with IC concentration and δ13C of carbonate. IC concentration and δ13C of carbonate in sediments of Lake Chenghai are good proxies for climatic warm/cold changes.展开更多
从北京通州地区3个河流沉积物和天津渤海湾地区4个土壤样品中提取胡敏酸(HA)和非水解碳(NHC),并进行了元素分析、X射线光电子能谱分析(XPS)、傅里叶变换红外光谱(FTIR)和固态13 C核磁共振(13 C NMR)等一系列定性定量的研究。结果显示:...从北京通州地区3个河流沉积物和天津渤海湾地区4个土壤样品中提取胡敏酸(HA)和非水解碳(NHC),并进行了元素分析、X射线光电子能谱分析(XPS)、傅里叶变换红外光谱(FTIR)和固态13 C核磁共振(13 C NMR)等一系列定性定量的研究。结果显示:同一来源的NHC中H/C和O/C比值低于HA的H/C和O/C比值;NHC和HA表面含氧官能团的含量分别为7.6%～10.7%,40.9%～46.7%;13 C NMR和FTIR显示NHC主要由脂肪碳和芳香碳组成;从土壤中比从沉积物中提取的NHC的芳香度高。研究结果表明,与HA相比,NHC的热成熟度高,疏水性强。展开更多
基金Supported by National Key Basic Research Fund (No. 2004CB720205) and National Nature and Science Foundation of China (No. 40331003).
文摘On the basis of multi-proxy analysis on TOC, TN, C/N, organic δ^13C and grain size, sediment record from Qinghai Lake provides evidences of stepwise-pattemed climatic change since 16 ka BE Results show that Qinghai Lake underwent six environmental stages. From 16.2 to 14.3 ka BP and from 4.0 to 2.1 ka BP, the organic δ^13C value was controlled by the concentration of atmospheric CO2. Relative higher organic δ^13C values occurred between 14.3 to 10.4 ka BP indicative of water hardness decrease resulted from melting ice water, corresponding to two intervals of C/N peak values to the Boling and AIlerod warm periods in Europe respectively. From 10.4 ka BP, Qinghai Lake entered the Holocene and the climate was warm and a little dry. The Megathermal appeared at about 6.7 ka BP when the vegetation around the lake transformed into a forest. Between 6.3 ka BP and 4.0 ka BP, the temperature decreased and δ^13C value was controlled by the expansion of C3 plants and the retreat of C4 plants in river catchment. Since 4.0 ka BP, the climate gradually became cold and dry. From 2.1 ka BP, the cold-dry climate and human activity resulted in an abrupt increase in C/N with deceased δ^13C value; meanwhile, many coarse grains appeared in sediments.
基金This work was supported by the Knowledge Innovation Project of Chinese Academy of Sciences (KZCX2-105) the Innovation Realm Project of the State Key Laboratory of Environmental Geochemistry and the National Natural Science Foundation of China (Gran
文摘Based on careful sampling and accurate analysis of recent sediments in Lake Chenghai, this paper discusses the staggered positive/negative correlation between organic carbon (OC) concentration and inorganic carbon (IC) concentration. The result indicates that temperature change, and its induced relative changes are the main factors affecting the relationship between IC concentration, δ13C of carbonate and OC concentration. When temperature and its induced photosynthesis strength change control autochthonous calcite precipitation, OC concentration is positively correlated with IC concentration and δ13C of carbonate. When temperature and its induced physical/chemical changes dominate, OC concentration displays negative correlation with IC concentration and δ13C of carbonate. IC concentration and δ13C of carbonate in sediments of Lake Chenghai are good proxies for climatic warm/cold changes.
文摘从北京通州地区3个河流沉积物和天津渤海湾地区4个土壤样品中提取胡敏酸(HA)和非水解碳(NHC),并进行了元素分析、X射线光电子能谱分析(XPS)、傅里叶变换红外光谱(FTIR)和固态13 C核磁共振(13 C NMR)等一系列定性定量的研究。结果显示:同一来源的NHC中H/C和O/C比值低于HA的H/C和O/C比值;NHC和HA表面含氧官能团的含量分别为7.6%～10.7%,40.9%～46.7%;13 C NMR和FTIR显示NHC主要由脂肪碳和芳香碳组成;从土壤中比从沉积物中提取的NHC的芳香度高。研究结果表明,与HA相比,NHC的热成熟度高,疏水性强。
