Simulating the exchanges of carbon dioxide, water vapor and heat over Changbai Mountains temperate broad-leaved Korean pine mixed forest ecosystem

A process-based ecosystem productivity model BEPS (Boreal Ecosystem Productivity Simulator) was updated to simulate half-hourly exchanges of carbon, water and energy between the atmosphere and terrestrial ecosystem at a temperate broad-leaved Korean pine forest in the Changbai Mountains, China. The BEPSh model is able to capture the diurnal and seasonal variability in carbon dioxide, water vapor and heat fluxes at this site in the growing season of 2003. The model validation showed that the simulated net ecosystem productivity (NEP), latent heat flux (LE), sensible heat flux (Hs) are in good agreement with eddy covariance measurements with an R2 value of 0.68, 0.86 and 0.72 for NEP, LE and Hs, respectively. The simulated annual NEP of this forest in 2003 was 300.5 gC/m2, and was very close to the observed value. Driving this model with different climate scenarios, we found that the NEP in the Changbai Mountains temperate broad-leaved Korean pine mixed forest ecosystem was sensitive to climate variability, and the current carbon sink will be weakened under the condition of global warming. Furthermore, as a process-based model, BEPSh was also sensitive to physiological parameters of plant, such as maximum Rubisco activity (Vcmax) and the maximum stomatal conductance (gmax), and needs to be carefully calibrated for other applications.     

大兴安岭中北部晚侏罗世-早白垩世地层新认识

根据大兴安岭中北部地区晚侏罗世火山岩正常沉积夹层中所含叶肢介化石的研究成果和同位素年龄新资料，认为大兴安岭北部西坡被归入白音高老组中的“含Eosestheria的酸性、酸碱性火山碎屑岩和熔岩”不是白音高老组，应归入龙江组，层位与辽西义县组对比。大兴安岭主脊火山岩（满克头鄂博组、玛尼吐组、白音高老组）从南到北是同期火山活动作用的结果，不存在“穿时”现象，形成于晚侏罗世早中期，层位与冀北大北沟组对比。     

THE INTERDECADAL VARIABILITY OF EAST ASIA MONSOON AND ITS EFFECT ON THE RAINFALL OVER CHINA

1 INTRODUCTION It is known early on that the intensity of East Asia monsoon affects the climate change in China and prompts much research in this aspect[1, 2]. The research also shows that the East Asia monsoon plays a more important role than the Indian …     

Grenvillian U-Pb zircon ages of quartz porphyry and rhyolite clasts in a metaconglomerate at Vimsodden, southwestern Spitsbergen

Proterozoic metasupracrustal rocks form a NNW-SSE trending basement zone along the western coast of Spitsbergen. The rocks show complex structures as a result of both Caledonian and Tertiary deformation, and most of the subordinate metaigneous rocks are not suitable for isotopic age determination. Some zircon-bearing rocks were found in the southwestern part of Spitsbergen and an attempt of U-Pb dating was performed.
U-Pb dating was carried out on zircon fractions from quartz porphyry and rhyolite clasts in a metaconglomerate unit of the Pyttholmen Formation northwest of Hornsund, southwestern Spitsbergen. The Pyttholmen Formation is considered to be a lateral equivalent of the upper part of the Gulliksenfjellet quartzite and in the same time as the upper part of the Skålfjellet metavolcanites. Therefore, the obtained ages are applicable to the age of the Skålfjellet igneous activities. Some of the dated samples are strongly schistose and their magmatic origin is difficult to confirm; the interpretation of the isotopic results is not well constrained; however, some explanations are possible which refer to the known geological conditions; an igneous age of siliceous volcanic rocks of ca. 1200 Ma, inherited zircon ages of ca. 2500 Ma and a regional metamorphic age of ca. 930 Ma. The last age belongs to the Grenvillian period and is conformable with the Rb/Sr whole rock age obtained from the garnet-biotite schists of the Isbjernhamna Group underlying the Skålfjellet metavolcanites.     

IMPACTS OF THE ONSET OF THE SOUTHEAST ASIAN SUMMER MONSOON ON THE BEGINNING OF THE RAINY SEASON IN YUNNAN

1 INTRODUCTIONSummer monsoon in Southeast Asia can causelarge-scale precipitation in the region in early summer,which is featured by prevailing low-level southwesterlyfrom the Bay of Bengal to South China Sea (SCS). Ithas characteristics of its own as well as those of Asianmonsoons in general. As found in studies over recentyears on East Asian monsoons[1],the earliest onset ofthe Southeast Asian summer monsoon occurs in earlysummer over the SCS, among all members of themonsoon syst…     

超深基坑支护设计与施工

拟建场地地势相对较高,地貌单元隶属太湖冲积平原虞西高亢平原亚区,主要为第四系河流相冲积。介绍在拟建的建筑物超深基坑支护中,将多种支护方法进行组合,以达到理想的效果。     

基于方差分量估计的CHAMP重力场恢复方法

基于德国慕尼黑技术大学(TUM)提供的100 d的CHAMP卫星几何法轨道和GFZ提供的加速度计数据,计算出了50×50阶地球重力场模型XISM-CHAMP01,并与EIGEN-CG03C、EIGEN-CHAMP03S、EIGEN2、EIGEN1S、EGM96模型进行了比较。结果表明,XISM-CHAMP01模型精度明显优于相同阶次EGM96模型和EIGEN1S模型,并与EIGEN2模型精度相当。     

碎屑流堆积物粒度分布与运动特性的关系——以贵州纳雍普洒村崩塌为例

对碎屑流堆积物的研究能反应碎屑流动能的变化。文章在普洒村崩塌现场调查的基础上结合崩塌堆积体高分辨率数字地表模型（DSM）,对崩塌碎屑流部分粒径进行统计分析,再结合谢德格尔公式估算崩塌碎屑流运动速度,对碎屑流运动过程进行初步分析,得到如下结论:（1）统计堆积体沿主滑方向的13个连续矩形区（A1~A13区）表面块石粒径,总结其规律为:越远离崩塌源区,小粒径含量越多,大粒径含量越少。（2）堆积物粒径和碎屑流运动动能有关,速度越大,其携带块石的能力越大,反之,块石含量越少。（3）根据块石堆积的不同特点,将堆积区域划分为初始堆积区、集中堆积区、平稳堆积区以及堆积减弱区。     

冬小麦基肥尿素氮的N_2排放损失（英文）

准确定量施肥农田土壤的N_2排放仍然困难。本研究基于华北冬小麦季的一次基肥(尿素150 kg N ha~(–1))施用事件,采用氦培养-直接测定N_2法,在与田间土壤温度和氧气含量一致的条件下测定鲜土的N_2和N_2O排放。结果显示:施肥和灌溉/降雨事件共同促进N_2和N_2O出现峰值排放;施肥导致N_2O/(N_2O+N_2)摩尔比增加至0.25;基肥施用后的一个月内,土壤N_2和N_2+N_2O排放损失分别占肥料氮投入的1.6%和2.2%。我们的结果证实了广泛采用的乙炔抑制法极大的低估了冬小麦田石灰性土壤N_2排放造成的肥料氮素损失。