Separating the effects of climate change and human activities on runoff over different time scales in the Zhang River basin

Most studies on separating the effects of climate change and human activities on runoff are mainly conducted at an annual scale with few analyses over different time scales, which is especially essential for regional water resources management. This paper investigates the impacts of climate change and human activities on runoff changes at annual, seasonal and monthly time scales in the Zhang River basin in North China. Firstly, the changing trends and inflection point are analyzed for hydro-climatic series over different time scales. Then the hydrological modeling based method and sensitivity based method are used to separate the effects. The results show that the effect of climate change is stronger than that of human activities on annual runoff changes. However, the driving factors on runoff are different at seasonal scale. In the wet season, the effect of human activities on runoff, accounting for 57 %, is stronger than that of climate change, while in the dry season climate change is the dominant factor for runoff reduction and the contribution rate is 72 %. Furthermore, the effects of climate change and human activities on monthly runoff changes are various in different months. The separated effects over different time scales in this study may provide more scientific basis for the water resources adaptive management over different time scales in this basin.     

The measurement and model construction of complex permittivity of vegetation

The complex permittivity of targeted objects is an important factor that influences its microwave radiation and scattering characteristics. In the quantitative research of microwave remote sensing, the study of the dielectric properties of the vegetation to establish the relationship between its specific physical parameters and complex permittivity is fundamental. In this study, six categories of vegetation samples were collected at the city of Zhangye, a key research area of the Heihe watershed allied telemetry experimental research. The vector network analyzer E8362B was used to measure the complex permittivity of these samples from 0.2 to 20 GHz by the coaxial probe technique. The research focused mainly on the corn leaves, and an empirical model was established between the gravimetric moisture and the real/imaginary parts of complex permittivity at the main frequency points of microwave sensors. Furthermore, the empirical model and the classical Debye-Cole model were compared and verified by the measured data collected from the Huailai County of Hebei Province. The results show that the newly-established empirical model is more accurate and more practical as compared to the traditional Debye-Cole model.     

Paleotemperature variations at Lake Caohai,southwestern China,during the past 500 years:Evidence from combined δ~(18)O analysis of cellulose and carbonates

The oxygen isotopic values of aquatic plant cellulose and carbonates in Lake Caohai sediments were measured using a continuous flow isotopic ratio mass spectrometer(CF-IRMS).Because of predictable oxygen isotopic fractionation between cellulose and its source water,the oxygen isotopic composition of paleo-lake water has been established quantitatively.Combined oxygen isotopic values of cellulose and carbonates were used in the‘Craig’equation to determine paleotemperatures and their variation in the lake during the past 500 years.Results show that the paleotemperature trend correlates well with meteorological records from Weining.There are four notable cold intervals at Lake Caohai over the past 500 years,namely 1540–1570AD,1670–1715AD,1780–1870AD and 1900–1930AD,and the former three cold intervals have been observed in the conventional Little Ice Age(LIA).These cold periods at Lake Caohai correspond well with those recorded from tree ring,peat,and ice core data from adjacent regions,particularly temperature those inferred fromδ18O of peat cellulose from Hongyuan Southwestern China.The trend in paleotemperature variations at Lake Caohai are also consistent with both the change of Indian summer monsoon,derived fromδ18O values of a stalagmite in Dongge,and a recorded shift in solar activity.The findings of this study illustrate that coupled analysis ofδ18O values of cellulose and carbonates from lake sediments may be used as a paleotemperature proxy.These results also provide further evidence of the existence of LIA in southwestern China.     

模拟雷电流冲击金属材料的金相组织分析

金相组织分析是雷电灾害鉴定的重要方法之一.通过模拟雷电流冲击的不同金属材料试验,并对其冲击材料进行金相组织分析,重点从材料微观结构变化研究雷电流对金属材料的影响.结果表明:模拟雷电流冲击后的金属材料其金相组织结构发生明显变化(缺陷增多);不同金属材料冲击后内部金相组织结构变化有明显差异;相同材质的金属材料冲击后,其金相组织结构变化幅度与其截面积大小成反比.     

欧盟航空碳税及其国际影响

根据当前欧盟征收国际航空碳税政策的国际环境,介绍欧盟航空碳税的历史沿革、具体政策、二氧化碳排放监测方法,就各国反应及其国际影响进行分析.欧盟航空碳税可能会导致全球航空业成本增加,并最终转嫁给消费者;欧盟航空碳税对发达国家航空公司影响较小,而对发展中国家的航空公司影响较大.鉴于欧盟航空碳税对中国航空业的影响,建议尽早制定相关的碳排放标准,维护中国应有的发展权与话语权.     

第二次全国土地调查成果质量检查系统开发

采用ArcGIS Engine,基于.NET软件开发环境,集成数据库、地理信息系统等多种技术,基于质检细则,并进行规则配置,开发第二次全国土地调查成果质量检查系统,通过全国免费使用,大幅提高了工作效率,确保了全国2800多个县市的第二次全国土地调查成果的规范一致和正确。本成果对土地利用数据质量的检查方式和方法,做了很好的探索和尝试,可以应用于今后每年的土地变更调查、国家土地利用规划数据汇交的数据质量检查工作中。     

骊山凸起隆升的时限及其地质意义

根据渭河盆地灞河期和游河期的地层沉积特征及分布范围,推断骊山凸起的隆升时期为晚中新世,游河期渭河盆地形成了西安凹陷和固市凹陷两个沉积中心,现今渭河盆地凸起和凹陷的并存的地貌格局很可能自晚中新世就已经形成。渭河盆地周缘在8Ma左右存在一次强烈区域隆升事件,对秦岭的隆升有显著影响。     

岩溶关键带及其碳循环研究进展

岩溶关键带的范畴包含了大气-(降水)-植被-土壤-裂隙-基岩-水组成的“碳-水-钙”循环强烈的表层岩溶带以及岩溶管道-洞穴-地下河-隔水层组成的巨大岩溶地下空间,岩溶关键带碳循环是岩溶地球系统科学研究的前沿方向。总结概括了岩溶地球系统科学发展至今的岩溶关键带范畴内碳循环及其对大气CO2源汇效应的研究成果,包括早期碳运移模型、当前主流的区域岩溶碳汇量的计算方法和结果以及“生物碳泵”的新发现等,讨论了当前岩溶碳循环研究框架过于单一或不一致以及碳周转时间尺度等问题,提出应对岩溶关键带碳输入、赋存以及碳输出的各个环节做出系统化监测,通过联网在线高分辨率监测站点的建设以及“3S”技术实现点位到区域的研究,使岩溶碳汇在全球碳循环模型中的重要性更具说服力。     

The State of Arts: Sources,Microbial Processes and Ecological Effects of Iron in the Marine Environment

Iron is the fourth most abundant element in the earth's crust, and it often appears as a trace element in the ocean. Iron has a variable valence and diverse functions, and is an important force to regulate marine primary productivity and drive the geochemical cycle in the ocean. Previous studies have shown that iron plays an important role in maintaining primary productivity, coupling matter cycles, and regulating the transformation of biogenic factors. In recent years, with the development of microbial ecology, iron research has enter more in-depth levels, including microbial-driven iron oxidation-reduction behavior, metabolic processes, and interactions with other major elements(C/N/P). This paper attempts to review the latest progress of iron, focusing on the published literatures of the past fifteen years. Firstly, we explained the sources and occurrence states of iron in the ocean (such as dissolved, colloidal, granular and organic state); Secondly, we reviewed the types and process mechanisms of microbial-mediated iron redoxbehavior (for example nitrate oxidation, and biological reduction, etc.); Finally, we summarized the coupling relationship between iron and C/N/P cycle. Additionally, the ecological roles of iron in specific ecological event (for instance algal bloom) has also been described. Furthermore, the "chemical-biological-physical" theoretical framework for marine iron research is also discussed. The purpose of this paper is to provide more information for marine microecological research and their effects on iron cycle under changing environment, such as global change.     

Effects of Fe and Al incorporations on the bridgmanite–postperovskite coexistence domain

The postperovskite phase transition of Fe and Al-bearing MgSiO₃ bridgmanite, the most aboundant mineral in the Earth's lower mantle, is believed to be a key to understanding seismological observations in the D″ layer, e.g., the discontinuous changes in seismic wave velocities. Experimentally reported phase transition boundaries of Fe and Al-bearing bridgmanite are currently largely controversial and generally suggest wide two-phase coexistence domains. Theoretical simulations ignoring temperature effects cannot evaluate correctly two-phase coexistence domains under high-temperature. We show high-pressure and high-temperature phase transition boundaries for various compositions with geophysically relevant impurities of Fe²⁺SiO₃, Fe³⁺Fe³⁺O₃, Fe³⁺Al³⁺O₃, and Al³⁺Al³⁺O₃ derived from the ab initio finite-temperature free energies calculated combining the internally consistent LSDA + U method and a lattice dynamics approach. We found that at ～ 2500 K, incorporations accompanied by Fe³⁺ expand the two-phase coexistence domains distinctly, implying that D″ seismic discontinuities likely arise from the phase transition of Fe²⁺-bearing bridgmanite.