Multi-level CO2 fluxes over Beijing megacity with the eddy covariance method

本文基于北京325米气象塔在47,140,和280米三层高度的5年涡动相关观测资料,研究了城市下垫面与大气间的CO2交换过程.由于北京市2011年开始实行工作日汽车尾号限行,140米高度CO2通量的年增长率由2008-2010年的7.8％降低到2010-2012年的2.3％.140米高度通量源区内植被比例最小且人口密度最大,因此140米高度的5年平均CO2通量年总量)6.41 kg C m-2 yr-1(大于47米)5.78 kg C m-2 yr-1(和280米)3.99 kg C m-2 yr-1(.在年尺度上,北京汽车总保有量和总人口是最重要的CO2通量控制因子.CO2通量随风向的变化主要与风向对应的通量源区内下垫面土地利用方式有关.三层高度的夏季CO2通量均与道路的比例呈正相关关系.47,140,和280米的决定系数分别为0.69,0.57,和0.54(P＜0.05).植被比例的下降,会导致CO2年总量上升,两者存在近似于指数的关系.城市人口密度的上升会引起CO2年总量上升.     

Cadmium isotopic constraints on metal sources in the Huize Zn-Pb deposit,SW China

The Sichuan-Yunnan-Guizhou(SYG)Zn-Pb metallogenic zone in SW China contains＞400 carbonate-hosted hydrothermal Zn-Pb deposits.Some of these,such as the Huize,Tianbaoshan,and Daliangzi deposits,are super-large deposits with significant reserves of Cd,Ge,and Ag.However,the sources of these metals remain controversial.This study investigated the Cd isotopic geochemistry of the Huize deposit,the largest Zn-Pb deposit in the SYG area.Sphalerites formed at three stages in the deposit have different colors:black or dark brown(Stage Ⅰ),red(Stage Ⅱ),and light-yellow(Stage Ⅲ).The δ114/110Cd values of the sphalerites are in the order Stage Ⅲ＜Stage Ⅰ＜Stage Ⅱ.Kinetic isotopic fractionation is likely the key factor causing the lower δ114/110Cd values in the early formed Stage Ⅰ sphalerites than in later-formed Stage Ⅱ sphalerites,with cooling of ore-forming fluids being responsible for the still lower values of the Stage Ⅲ sphalerites.In galena,the δ114/110Cd values are inversely correlated with Cd contents and tend to be higher in high-Zn galena.We speculate that Cd isotopic fractionation was significant during the precipitation of sphalerite and galena,with light Cd isotopes being enriched in galena rather than sphalerite.Comparison of the Cd isotopic signatures and Zn/Cd ratios of different endmembers suggests that the δ114/110Cd values and Zn/Cd ratios of sphalerite from the Huize deposit,as well as other large-scale deposits from the SYG area,are lie in those range of Emeishan basalts and sedimentary rocks and the mean δ114/110Cd values of these deposits show good negative correlation with 1/Cd,suggesting that the ore-forming materials of these deposits were derived from the mixing of Emeishan basalts and sed-imentary rocks.This study demonstrates that Cd isotopes can be useful proxies in elucidating ore genesis in large Zn-Pb deposits.     

Stability and band gap engineering of silica-confined lead halide perovskite nanocrystals under high pressure

SiO₂is the major mineral substance in the upper mantle of the earth.Therefore,studies of the silica-coated materials under high-pressure are essential to explore the physical and chemical properties of the upper mantle.The silica-confined CsPbBr₃nanocrystals(NCs)have recently attracted much attention because of the improved photoluminescence(PL)quantum yield,owing to the protection of silica shell.However,it remains considerable interest to further explore the relationship between optical properties and the structure of CsPbBr₃@SiO₂NCs.We systemically studied the structural and optical properties of the CsPbBr₃@SiO₂NCs under high pressure by using diamond anvil cell(DAC).The discontinuous changes of PL and absorption spectra occurred at~1.40 GPa.Synchrotron X-ray diffraction(XRD)studies of CsPbBr₃@SiO₂NCs under high pressure indicated an isostructural phase transformation at about 1.36 GPa,owing to the pressure-induced tilting of the Pb-Br octahedra.The isothermal bulk moduli for two phases are estimated about 60.0 GPa and 19.2 GPa by fitting the equation of state.Besides,the transition pressure point of CsPbBr₃@SiO₂NCs is slightly higher than that of pristine CsPbBr₃NCs,which attributed to the buffer effect of coating silica shell.The results indicate that silica shell is able to enhance the stabilization without changing the relationship between optical properties and structure of CsPbBr₃NCs.Our results were fascinated to model the rock metasomatism in the upper mantle and provided a new‘lithoprobe’for detecting the upper mantle.     

Tectono-Magmatic Activization and Fractal Dynamics of Ore-Forming of Hydrothermal Uranium Deposits in South China

Please refer to the attachment(s) for more details.     

Changes in Winter Stratospheric Circulation in CMIP5 Scenarios Simulated by the Climate System Model FGOALS-s2

Diagnosis of changes in the winter stratospheric circulation in the Fifth Coupled Model Intercomparison Project(CMIP5) scenarios simulated by the Flexible Global Ocean-Atmosphere-Land System model,second version spectrum(FGOALS-s2),indicates that the model can generally reproduce the present climatology of the stratosphere and can capture the general features of its long-term changes during 1950-2000,including the global stratospheric cooling and the strengthening of the westerly polar jet,though the simulated polar vortex is much cooler,the jet is much stronger,and the projected changes are generally weaker than those revealed by observation data.With the increase in greenhouse gases(GHGs) effect in the historical simulation from 1850 to 2005(called the HISTORICAL run) and the two future projections for Representative Concentration Pathways(called the RCP4.5 and RCP8.5 scenarios) from 2006 to 2100,the stratospheric response was generally steady,with an increasing stratospheric cooling and a strengthening polar jet extending equatorward.Correspondingly,the leading oscillation mode,defined as the Polar Vortex Oscillation(PVO),exhibited a clear positive trend in each scenario,confirming the steady strengthening of the polar vortex.However,the positive trend of the PVO and the strengthening of the polar jet were not accompanied by decreased planetary-wave dynamical heating,suggesting that the cause of the positive PVO trend and the polar stratospheric cooling trend is probably the radiation cooling effect due to increase in GHGs.Nevertheless,without the long-term linear trend,the temporal variations of the wave dynamic heating,the PVO,and the polar stratospheric temperature are still closely coupled in the interannual and decadal time scales.     

Observational constraints on the early dark energy model

Dark energy can be studied by its influence on the expansion of the Universe.We investigate current constraints on early dark energy(EDE) achievable by the combined observational data from type Ia supernovae(557),baryon acoustic oscillations,the current cosmic microwave background and the observed Hubble pa-rameter.We find that combining these data sets provides powerful constraints on early dark energy and the best fit values of the parameters in 68% and 95% confidence-level regions are:Ωm0=0.2897 +0.0149+...     

PRELIMINARY STUDY OF VARIATION OF SO2 AND AEROSOL PARTICLE BACKGROUND CONCENTRATIONS IN THE EASTERN CHINA

The average concentrations of sulphur dioxide,sulfate aerosol and TSP were about 8-10 ppb,15.08 μg m^-3,and 241.40 μg m^-3 respectively,which were measured at the Lin'an regional background station during August-November,1991.The higher concentrations of SO₂ and SO₄^2- maybe acidify the rainfall.It has a great influence upon the human health and ecosystem.The simulated results indicate that the distributions of SO₂ and SO₄^2- were determined by local emission sources.Average aerosol particle number density was 2.0×10⁴ cm^-3.It shows that social development and human activities strongly affect the atmospheric background level.