E5000型全谱直读型电弧发射光谱仪研制及其在地球化学样品分析中应用

在地球化学样品检测工作中,Ag、B、Sn等难分析元素通常采用传统的交流电弧发射光谱法(摄谱仪),随着地球化学样品数量的增加以及对检测结果质量要求的提高,该方法操作复杂、分析过程繁琐的问题与日常大量样品分析的矛盾日益突出,多道式电弧直读发射光谱也开始在行业内应用。本文基于先进的数字光源技术和CCD全谱型光谱仪技术,改进了电弧发生系统、分光系统和检测系统,将电弧激发光源与Paschen-Runge型全谱CCD光谱仪结合,研制了一款新型的台式全谱直读型电弧发射光谱仪E5000。E5000型电弧发射光谱仪通过激光定位结合程控电极技术,自动调整电极位置,提高了采谱过程的精度控制;利用CCD全谱技术获得了激发样品的全谱信息,可轻易实现光谱信号的背景扣除和干扰校正;且无需再次测定黑度,直接获得分析结果;同时结合内标法和标准加入法,可以进一步提高复杂基体样品的分析精准度。应用研制的光谱仪对水系沉积物和土壤样品进行检测,Ag、B、Sn元素的检出限分别达到了0.01μg/g、0.65μg/g、0.16μg/g,在分析水系沉积物、土壤时检测精密度基本小于10%,优于当前的摄谱法和多道电弧直读光谱法,满足了地球化学样品检测质量要求。     

西秦岭阳山金矿带安坝矿床热液蚀变作用

安坝金矿床是阳山金矿带内已探明金资源储量最大的金矿床,矿体受NEE向的区域性安昌河-观音坝断裂带及其次级断裂-裂隙系统控制,主要赋存于紧邻断裂带的千枚岩和斜长花岗斑岩中。围绕断裂-裂隙系统的赋矿围岩硫化、硅化、绢云母化、碳酸盐化、绿泥石化、绿帘石化和粘土化蚀变发育,其中前三种蚀变与金成矿作用关系最为密切。论文在厘定安坝金矿床热液蚀变类型、矿物组合特征、以及断裂变形与蚀变空间变化关系的基础上,通过对蚀变岩及其原岩的地球化学分析,剖析了热液蚀变作用过程与机理。研究结果表明,硅化蚀变贯穿发育于成矿前、成矿期和成矿后,绢云母化蚀变为成矿前和成矿期的产物,碳酸盐化蚀变主要发育于成矿晚阶段和成矿后,而粘土化蚀变为成矿后的产物。在长石蚀变为绢云母的过程中,有少量Al2O3带出,而TiO 2在蚀变过程中相对稳定,为此选取TiO 2作为不活动组分,开展质量平衡计算得出:在硅化过程中,明显带入的组分有SiO 2、Fe2O3、FeO、MgO、CaO、C、S、Au、As、Hg、Pb和Zn,而被带出的元素为Rb和Ba;在绢云母化过程中,明显带入的组分为SiO 2、Fe2O3、CaO、C、S、Au、As、Hg、Pb、Zn、Rb和Ba,带出组分为Na2O。稀土元素地球化学特征显示千枚岩原岩稀土元素含量比硅化和绢云母化千枚岩的稀土元素含量高,表明在蚀变过程中有稀土元素的流失。此外,千枚岩原岩的δEu=0.70,δCe=0.95;硅化千枚岩的δEu=0.72,δCe=1.00;绢云母化千枚岩的δEu=0.76,δCe=0.95。硅化、绢云母化千枚岩与千枚岩原岩的REE球粒陨石标准化配分模式曲线变化趋势相似,表现为明显的Eu负异常、无Ce异常的富轻稀土的右倾型曲线。含矿流体沿断裂带运移并与围岩反应,形成了石英和绢云母等蚀变矿物。硅化过程中,含矿流体中还原硫活度降低导致金沉淀;而绢云母化过程中,含矿流体的pH增大及K+和H+含量的减少和CO2含量的增加,致使载金黄铁矿、毒砂和金的沉淀。     

Geochemistry of the Eocene Jijuntun Formation oil shale in the Fushun Basin,northeast China: Implications for source-area weathering,provenance and tectonic setting

Within the fault-bound Fushun Basin of northeastern China, the Eocene Jijuntun Formation hosts extensive deposits of thick lacustrine oil shale. Systematic sampling and geochemical analysis of these deposits has revealed that the parent rocks of the oil shale underwent moderate chemical weathering; and that its mineralogy and trace and rare earth element geochemistry were mainly controlled by parent rock composition, with no synsedimentary changes in the source terrain. Based on source rock and tectonic setting discrimination diagrams, we concluded that the parent rocks of the oil shale were mostly basalts of the Paleogene Laohutai Formation. These basalts originated in a continental back arc environment and contain abundant nutrient elements such as Fe, P, Ni, Cu and Zn, all of which are essential for the growth of aquatic photoautotrophs in lakes. Continuous, high primary productivity in the Jinjuntun lacustrine depocentre, combined with a stable tectonic setting and underfilled sedimentary environment, were key factors in the genesis of its oil shale.     

Study of dispersion of mass distribution of ultra-high energy cosmic rays using a surface array of muon and electromagnetic detectors

We consider a hypothetical observatory of ultra-high energy cosmic rays consisting of two surface detector arrays that measure independently electromagnetic and muon signals induced by air showers. Using the constant intensity cut method, sets of events ordered according to each of both signal sizes are compared giving the number of matched events. Based on its dependence on the zenith angle, a parameter sensitive to the dispersion of the distribution of the logarithmic mass of cosmic rays is introduced. The results obtained using two post-LHC models of hadronic interactions are very similar and indicate a weak dependence on details of these interactions.     

GRAPES_GFS中三维参考大气的研究：参考态构造和实际预报试验

GRAPES_GFS（Global Regional Assimilation and PrEdiction System, Global Forecast System）采用基于等温大气构造的一维参考大气,前期的研究工作已在GRAPES_GFS的动力框架中引入了三维参考大气,并通过一系列理想试验检验了新方法的正确性以及计算精度。本部分研究工作,主要针对实际资料的预报试验,对比分析了不同三维参考态给定方法的优劣,并采用气候平均法,进行夏季两个月的四维变分循环预报试验。检验结果显示,使用三维参考大气后,模式的综合预报性能得到了提升,对流层高度场、温度场的预报偏差有所减小,长期积分过程中模式质量损失较为严重的问题也得到了明显的缓解。另外,通过动能谱的对比也可以看到使用三维参考大气后,模式在高层的能量耗散明显较小,能谱变化与观测更加吻合。      

Simulation of coupled pelagic-benthic ecosystem of the Yellow Sea Cold Water Mass

A one-dimensional coupled pelagic-benthic box model for the Yellow Sea Cold Water Mass （YSCWM） is developed. The model is divided into three boxes vertically according to the depths of thermocline and euphotic layer. It simulates well the oligotrophic shelf ecosystem of the YSCWM considering effects of nutrients deposition and microbial loop. Main features of vertical structure of various variables in ecosystem of the YSCWM were captured and seasonal variability of the ecosystem was well reconstructed. Calculation shows that the contribution of microbial loop to the zooplankton can reach up to 60%. Besides, input of inorganic nutrients from atmospheric deposition is an important mechanism of production in upper layer of the YSCWM when stratified.     

Anthropogenic iodine-129 in seawater along a transect from the Norwegian coastal current to the North Pole

Variation in the concentrations of iodine-129 (129I, T1/2=15.7 Myr), a low-level radioactive component of nuclear fuel waste, is documented in surface waters and depth profiles collected during 2001 along a transect from the Norwegian Coastal Current to the North Pole. The surface waters near the Norwegian coast are found to have 20 times higher 129I concentration than the surface waters of the Arctic Ocean. The depth profiles of 129I taken in the Arctic Ocean reveal a sharp decline in the concentration to a depth of about 300-500 m followed by a weaker gradient extending down to the bottom. A twofold increase in the 129I concentration is observed in the upper 1000 m since 1996. Based on known estimates of marine transient time from the release sources (the nuclear reprocessing facilities at La Hague, France, and Sellafield, UK), a doubling in the 129I inventory of the top 1000 m of the Arctic Ocean is expected to occur between the years 2001 and 2006. As 129I of polar mixed layer and Atlantic layer of the Arctic Ocean is ventilated by the East Greenland Current into the Nordic Seas and North Atlantic Ocean, further dispersal and increase of the isotope concentration in these regions will be encountered in the near future.     

Climate during the last glacial maximum in the Wasatch and southern Uinta Mountains inferred from glacier modeling

Recent improvements in understanding glacial extents and chronologies in the Wasatch and Uinta Mountains and other mountain ranges in the western U.S. call for a more detailed approach to using glacier reconstructions to infer paleoclimates than commonly applied AAR-ELA-ÄT methods. A coupled 2-D mass balance and ice-flow numerical modeling approach developed by [Plummer, M.A., Phillips, F.M., 2003. A 2-D numerical model of snow/ice energy balance and ice flow for paleoclimatic interpretation of glacial geomorphic features. Quaternary Science Reviews 22, 1389–1406] allows exploration of the combined effects of temperature, precipitation, shortwave radiation and many secondary parameters on past ice extents in alpine settings. We apply this approach to the Little Cottonwood Canyon in the Wasatch Mountains and the Lake Fork and Yellowstone Canyons in the south-central Uinta Mountains. Results of modeling experiments indicate that the Little Cottonwood glacier required more precipitation during the local Last Glacial Maximum (LGM) than glaciers in the Uinta Mountains, assuming lapse rates were similar to modern. Model results suggest that if temperatures in the Wasatch Mountains and Uinta Mountains were  6 °C to 7 °C colder than modern, corresponding precipitation changes were  3 to 2× modern in Little Cottonwood Canyon and  2 to 1× modern in Lake Fork and Yellowstone Canyons. Greater amounts of precipitation in the Little Cottonwood Canyon likely reflect moisture derived from the surface of Lake Bonneville, and the lake may have also affected the mass balance of glaciers in the Uinta Mountains.     

Monitoring Mongolia Gobi dust transport using OMI data

The characteristics of long-distance dust transport from Asia to the United States over the Pacific Ocean are statistically analyzed using OMI AI (Ozone Monitoring Instrument Aerosol Index) data during 2005–2007. The results show that there is a high correlation of AI (the correlation coefficients are as high as 0.83 in March, 0.62 in April and 0.54 in May) between the Mongolia Gobi Desert and the west coast region of the United States (40°–50°N, 120°–130°W), indicating a strong source-receptor area relationship. Through calculating the lag correlation coefficient of the dust propagation time, we determined that the dust propagation time from the Mongolia Gobi Desert to the west coast of the United States is about 6–7 days at the 99% confidence level.     

AMIP模式对大气经向质量输送的模拟评估

从描述南、北半球间大气经向质量传输的角度人手,考察IPCC第4次评估报告提供的8个AMIP大气环流模式对越赤道质量通量输送的模拟性能。结果表明:NCAR、MPI和UKMO模式模拟出的越赤道整层大气质量通量与观测大体相一致;MIROC3模拟的整层大气质量通量年循环与观测结果相去甚远,尤其在夏季模拟出较强的虚假向北大气质量输送;IAP模拟的整层大气质量通量年循环方向与观测结果在7个月份中相反;把垂直大气分为4层.各模式对700 hPa以下(I_1)和300-70 hPa(I_3)两层质量通量的模拟能力普遍较好;对700-300 hPa层(I_2)质量通量模拟结果偏差较大;除MIROC3外,其余模式基本能够模拟出70-10 hPa(I_4)大气质量通量的季节变化.显然,不仅南、北半球间大气存在质量交换,越过其他纬度同样存在着经向大气质量输送,无论冬季、夏季还是年平均,各模式对越过其他纬度(60°S-60°N)经向大气质量输送的模拟结果与观测差异明显。整体权衡,UKMO_HADGEMl在模拟越赤道大气质量通量方面表现突出,MPI_ECHAM5模式优势较明显;NCAR、GISS和GFDL 3个模式在某些压力层内具有较好的模拟水平;MIROC模式对整层、700-300 hPa层的模拟能力较低,而对700 hPa以下层和300-70 hPa层的模拟水平较高;IAP_FGOALS和CNRM模式在模拟越赤道大气质量通量方面存在一定的不足.