青藏高原高寒湿地生态系统演变、修复与保护

 探讨了青藏高原高寒湿地的动态变化及演变趋势，分析了湿地面积变化、生态系统结构与功能退化现状与原因。分析表明，国家近20年来在青藏高原实施的生态保护、修复及生态工程项目取得了一定的成效，但高寒湿地生态系统的退化形势依然严峻。生态保护和修复是一项系统、长期的工作，今后要加强生态修复技术研发项目与工程类项目的衔接，建立长效管理机制，提高退化湿地的自然恢复能力。同时，要构建适于青藏高原高寒湿地保护效应的评价模型和指标体系，完善重大工程项目的系统监测与评价。在黄河、长江上游源区布局高寒湿地生态系统的长期监测，将与三江源区同样重要的黄河首曲湿地、若尔盖湿地纳入国家公园管理体系，统筹规划，建立健全科技服务平台和信息共享机制。     

Amplitudes, rates, periodicities and causes of temperature variations in the past 2485 years and future trends over the central-eastern Tibetan Plateau

Amplitudes, rates, periodicities, causes and future trends of temperature variations based on tree rings for the past 2485 years on the central-eastern Tibetan Plateau were analyzed. The results showed that extreme climatic events on the Plateau, such as the Medieval Warm Period, Little Ice Age and 20th Century Warming appeared synchronously with those in other places worldwide. The largest amplitude and rate of temperature change occurred during the Eastern Jin Event (343-425 AD), and not in the late 20th century. There were significant cycles of 1324 a, 800 a, 199 a, 110 a and 2-3 a in the 2485-year temperature series. The 1324 a, 800 a, 199 a and 110 a cycles are associated with solar activity, which greatly affects the Earth surface temperature. The long-term trends (>1000 a) of temperature were controlled by the millennium-scale cycle, and amplitudes were dominated by multi-century cycles. Moreover, cold intervals corresponded to sunspot minimums. The prediction indicated that the temperature will decrease in the future until to 2068 AD and then increase again.     

探讨高原地区甲醇沸程气压修正值

甲醇的沸程一直是甲醇产品质量控制的重要指标,目前国内企业生产的甲醇产品沸程均以GB／T7534和ASTMD1078为测定依据,而上述两种方法中均未对高原地区的参数修正做出规定,本文通过实验来探讨高原地区沸程测定时气压的修正值。     

Evolution of the East Asian monsoon and its response to uplift of the Tibetan Plateau since 1.8 Ma recorded by major elements in sediments of the South China Sea

Evolution of the East Asian monsoon and its response to uplift of the Tibetan Plateau has been investigated in the study of global change. Core sediment samples drilled in the South China Sea during ODP Leg184 are the best materials for studying long-term variability of the East Asian monsoon. R-mode factor analysis of major elements in the fine grain-sized carbonate-free sediments (<4 μm) of the upper 185 mcd splice of ODP Site 1146 drilled during Leg184 in the South China Sea shows that Ti, TFe2O3, MgO, K2O, P, CaO, and Al2O3 are representative of a terrestrial factor. The variation in the terrestrial factor score is subject to chemical erosion in the source region and thus indicates the evolution of the East Asian summer monsoon. The terrestrial factor score has three stepwise decreases at ~1.3 Ma, ~0.9 Ma, and ~0.6 Ma, indicating the phased weakening of the East Asian summer monsoon is related to wholly stepwise, quick uplifts of the Tibetan Plateau since 1.8 Ma. The periodic fluctuation of the terrestrial factor score since ~0.6 Ma indicates that the glacial-interglacial cycles have been the main force driving the evolution of the East Asian monsoon. As in the case of Chinese loess, the long-term evolution of the East Asian monsoon recorded in sediments of the South China Sea reflects a coupled effect of the glacial-interglacial cycle and uplift of the Tibetan Plateau.     

青藏高原腹地第四纪地质环境演化的地球动力学机制

根据古季风变化与生物生产总量之间的耦合关系，结合区域地质演变和地球卫星遥感影像解译成果，对引起高原内部古气候环境变化发展过程的启动激发因素和相互耦合机制及其驱动传递效应进行探索研究，这个方向目前仍然属于高原地质环境演变及全球变化的前沿领域。     

Climatic significance of n-alkanes and their compound-specific dD values from lake surface sediments on the Southwestern Tibetan Plateau

The content and hydrogen isotope ratios of n-alkanes extracted from recent lake surface sediments sampled from nine lakes in three different climate zones on the Southwestern Tibetan Plateau were analyzed.Values were compared with n-alkanes in plants from lake drainages,and dD values of meteoric water,lake water,and mean annual precipitation.The results showed that n-C23was predominantly derived from aquatic plants,and n-C27–n-C33from terrestrial higher plants.The average carbon chain length of n-C27–n-C33(ACL27–33)was positively correlated with the mean annual precipitation.dD values of the long-chain n-alkanes n-C29and n-C31of terrestrial origin(varying between-214%and-169%,and-226%and-185%,respectively)were inversely correlated with mean annual precipitation;but in accordance with the average annual variations in dD(OIPC),dD values of n-C31were strongly related to the dD values of growing season meteoric water(R2=0.74).The large difference between dD values of n-C23of aquatic origin and n-C31(an average of about 27%)demonstrates the enrichment of the lake water dD compared to precipitation,caused by strong evaporation in the semiarid–arid areas of the southwestern Tibetan Plateau.Average value of en C25 31=p(-95%)is evidently higher than the value observed in European wet regions(-128%);besides,en C31(about-116%)is constant along the study transect(SD=9),which indicates that n-C31is a useful proxy for the environment.     

Opening of the Longmu Co–Shuanghu–Lancangjiang ocean:constraints from plagiogranites

This paper reports new zircon U-Pb ages,and Hf isotope and whole-rock major and trace element data for Cambrian plagiogranites from the Tuobeiling ophiolite in central Qiangtang,Tibetan Plateau.Zircon SIMS and LAICP-MS U-Pb dating of the plagiogranites yield weighted mean ages of 504.8±4.2 and 491.6±1.5 Ma,respectively.The zircons from plagiogranites exhibit positive eHf(t)values(ranging from 11.46 to 15.16),indicating that the plagiogranites are derived from depleted mantle.These plagiogranites are characterized by high SiO2and Na2O,low K2O,low REE contents,and flat REE distribution patterns.These rocks have geochemical compositions typical of oceanic plagiogranite and,considered along with their petrography and field relationships,are interpreted to have derived from anatexis of hydrated amphibolites by ductile shearing during transports of the oceanic crust.The formation age of such type of plagiogranite is slightly younger than that of the associated section of oceanic crust.Thus the new results from these plagiogranites suggest that the Longmu Co–Shuanghu–Lancangjiang ocean had probably opened before the Middle Cambrian.     

生态建设工程对坝上农用地土壤风蚀治理的后效——以河北省张家口市康保牧场为例

通过在农牧交错带河北省张家口市坝上高原康保牧场野外调查研究,采用标桩法测定土壤风蚀厚度,计算土壤年风蚀量,采用目测法测定样地植被盖度.将该地生态建设初期与生态建设10年后的土壤风蚀量作对比.结果表明:生态建设十年后土壤风蚀量比生态建设初期土壤风蚀量明显减少,植被盖度明显增加.并提出巩固生态工程建设成果的若干建议.     

不同生境狭叶锦鸡儿灌丛沙堆的土壤微生物数量、分含量及酶活性的比较研究

为了解狭叶锦鸡儿灌丛沙堆的土壤微生物与生境、土壤养分及酶活性之间的关系,采集内蒙古高原不同生境下的狭叶锦鸡儿灌丛沙堆的土壤,测定土壤微生物的数量、土壤养分和土壤酶活性.研究发现：狭叶锦鸡儿灌丛沙堆土壤中的微生物数量和养分含量表现为典型草原＞荒漠草原＞荒漠;碱性磷酸酶活性表现为典型草原＞荒漠草原＞荒漠,脲酶、过氧化氢酶和蔗糖酶活性表现为荒漠草原＞典型草原＞荒漠.这些研究结果表明：狭叶锦鸡儿灌丛沙堆土壤微生物的数量和组成差异是由土壤营养、气候以及受气候决定的植被差异共同作用的结果;而土壤微生物与土壤酶活性之间的关系较为复杂.