气象-气溶胶资料联合同化对秋季PM2.5浓度模拟的影响研究

相比冬季大范围静稳条件下的污染堆积过程,秋季气象条件更加复杂和局地化,气象条件模拟不确定性给秋季气溶胶模拟带来了更大难度,且目前研究较少考虑气象-气溶胶因素在线模拟和联合同化。使用WRF/Chem模式和格点统计差值（GSI）三维变分同化系统,2015年10月进行了为期1个月的气象-气溶胶资料联合同化及模拟试验,并基于此讨论了气象-气溶胶资料联合同化对秋季PM_2.5浓度模拟的影响。结果表明,WRF/Chem模式可以模拟出秋季污染天气过程,但对华北平原和中东部地区存在高估、西北部存在低估现象;同化地面PM_2.5浓度观测资料可以改进对PM_2.5浓度的模拟,上述两个地区的偏差均得到订正,6 h预报偏差均降低至6 μg/m3以内;重点针对华北地区的分析表明,秋季PM_2.5污染过程与特殊气象条件（湿度升高、风场辐合、区域输送）密切相关,因此在地面PM_2.5观测资料同化基础上增加常规气象资料同化,能进一步提高对华北平原气象-污染过程的表达,PM_2.5浓度预报相关系数从0.86提高至0.89。气象-气溶胶联合资料同化能更加准确地模拟秋季气溶胶污染过程,为更好地开展污染成因和在气象预报框架下开展气象-气溶胶相互影响研究提供了基础。      

象山港大型底栖动物群落特征

2006年7月—2008年8月,对象山港全港海域设立的13个采样站位采集的调查资料,用物种丰富度指数、物种均匀度指数和物种多样性指数分析象山港大型底栖动物物种的多样性和群落种类的组成,以及采用ABC曲线方法和大型多元统计分析软件PRIMER5对象山港大型底栖动物进行Bray-Curtis相似性聚类分析和非度量MDS标序,研究象山港大型底栖动物群落结构。调查显示象山港大型底栖动物不同采样站位之间物种丰富度指数(d)、均匀度指数(J)、辛普森多样性指数(D)和香农-威纳多样性指数(H’)差异皆高度显著(P0.01)。群落结构聚类分析和MDS标序表明,13个采样站位的大型底栖动物群落大致可分为3组。根据所调查象山港大型底栖动物的丰度和生物量资料做的ABC曲线分析表明,该海域大型底栖动物群落受到了严重的环境污染或者扰动,逐渐由一种或几种个体较小的种类占优势。     

Identification of recycled continental material in the mantle from Sr,Nd and Pb isotope investigations

Pb, Nd and Sr isotope compositions of oceanic basalts have been used to identify recycled components of continent derivation in the mantle. The isotopic compositions of Sr, Nd and Pb, together with U, Pb, Sm, Nd, Rb, and Sr abundances have been determined for back-arc basalt glasses from the Scotia Sea and Parece Vela and West Philippine Basins, in addition to basalts from South Sandwich Islands, Ascension, St. Helena and Tristan da Cunha. Comparisons made between the isotopic compositions of South Sandwich Islands basalts and Atlantic MORB glasses permit the identification of recycled components of continent derivation in the source of the island arc basalts. Recycled Sr of continent derivation is also recognisable in back-arc basalt glasses from the Scotia Sea and Parece Vela and West Philippine Basins. However, contemporary reinjection of material with the isotopic structures similar to those identified as a component of island arc and back-arc regions cannot be the sole or dominant influence on the fine structure observed in MORB glasses from the Atlantic Ocean, nor the isotopic compositions of Tristan da Cunha, St. Helena and Ascension basalts. Recycled materials are likely to have been responsible for the generation of these heterogeneities only if they have been stored in the mantle for periods of time exceeding 10⁹ years.     

对我国LBS发展有关问题的思考和几点建议

基于位置的服务(LBS)被认为是目前最具发展前景的产业.一直以来,人们对LBS的内涵、发展和产业链等存在着不同的认识和理解.本文从LBS起源出发,对其发展历程、应用领域和产业链进行了全面的梳理和分析,提出目前存在的问题,并对地理信息主管部门在促进LBS产业发展方面,提出了几点建议.     

Teleportation and thermal entanglement in two-qubit Heisenberg XYZ spin chain with the Dzyaloshinski—Moriya interaction and the inhomogeneous magnetic field

This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg XYZ chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski--Moriya interaction. It shows that for a fixed D_z, the increase of b_z will broaden the critical temperature at the cost of decreasing the thermal entanglement. And it can modulate the inhomogeneous magnetic field and the Dzyaloshinski--Moriya interaction for the average fidelity of teleportation to be optimal.     

南北带强震年度预测能力估计

对中国地震局原分析预报中心测震学科1988～1999年度划定的南北地震带强震(M≥7)危险区进行了回顾和分析。 结果表明, 从过程角度研究前兆地震活动图像及其演变是年度和中短期强震预测的有效途径, 这为南北地震带强震震情跟踪提供了条件。     

Element partitioning during precipitation of aragonite from seawater: A framework for understanding paleoproxies

This study presents the results from precipitation experiments carried out to investigate the partitioning of the alkaline earth cations Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ between abiogenic aragonite and seawater as a function of temperature. Experiments were carried out at 5 to 75 °C, using the protocol of Kinsman and Holland [Kinsman, D.J.J., Holland, H.D., 1969. The coprecipitation of cations with CaCO₃ IV. The coprecipitation of Sr²⁺ with aragonite between 16 and 96 °C. Geochim. Cosmochim. Acta33, 1-17.] The concentrations of Mg Sr and Ba were determined in the fluid from each experiment by inductively coupled plasma-mass spectrometry, and in individual aragonite grains by secondary ion mass spectrometry. The experimentally produced aragonite grains are enriched in trace components (“impurities”) relative to the concentrations expected from crystal-fluid equilibrium, indicating that kinetic processes are controlling element distribution. Our data are not consistent with fractionations produced kinetically in a boundary layer adjacent to the growing crystal because Sr²⁺, a compatible element, is enriched rather than depleted in the aragonite. Element compatibilities, and the systematic change in partitioning with temperature, can be explained by the process of surface entrapment proposed by Watson and Liang [Watson, E.B., Liang, Y., 1995. A simple model for sector zoning in slowly grown crystals: implications for growth rate and lattice diffusion, with emphasis on accessory minerals in crustal rocks. Am. Mineral.80, 1179-1187] and Watson [Watson, E.B., 1996. Surface enrichment and trace-element uptake during crystal growth. Geochim. Cosmochim. Acta60, 5013-5020; Watson, E.B., 2004. A conceptual model for near-surface kinetic controls on the trace-element and stable isotope composition of abiogenic calcite crystals. Geochim. Cosmochim. Acta68, 1473-1488]. This process is thought to operate in regimes where the competition between crystal growth rate and diffusivity in the near-surface region limits the extent to which the solid can achieve partitioning equilibrium with the fluid. A comparison of the skeletal composition of Diploria labyrinthiformis (brain coral) collected on Bermuda with results from precipitation calculations carried out using our experimentally determined partition coefficients indicate that the fluid from which coral skeleton precipitates has a Sr/Ca ratio comparable to that of seawater, but is depleted in Mg and Ba, and that there are seasonal fluctuations in the mass fraction of aragonite precipitated from the calcifying fluid (“precipitation efficiency”). The combined effects of surface entrapment during aragonite growth and seasonal fluctuations in “precipitation efficiency” likely forms the basis for the temperature information recorded in the aragonite skeletons of Scleractinian corals.     

基于WRFDA-Chem三维变分同化系统的中国PM2.5和PM10资料同化试验北大核心CSCD

将大气化学三维变分同化系统WRFDA_Chem引入睿图—化学环境气象数值预报系统(RMAPS-Chem),利用2016年11月地面观测细颗粒物(PM2.5)和颗粒物(PM10)逐小时质量浓度资料进行同化预报试验:6 h循环同化结果表明,WRFDA-Chem对初始场PM2.5和PM10的模拟偏差和相关性有显著改善,均方根误差(RMSE)减小40%左右,相关性提高0.27~0.37;同化对预报改进能持续24 h以上,PM2.5(PM10)浓度预报RMSE降低25%(10%),相关性提升14%(25%);加密同化频次(逐小时循环同化)进一步改进预报效果。未来需要进一步开展同化数据质量控制方案研究以优化业务预报效果,并在深入理解模式不确定性和偏差来源的情况下,进一步开展模式和同化系统的协同发展。     

宁夏中奥陶统香山群徐家圈组大地构造环境分析

宁夏香山群为一套遭受轻微区域变质的陆源碎屑岩,并夹有少量碳酸盐岩和硅质岩,属于深水浊流沉积,从下到上可分为徐家圈组、狼嘴子组和磨盘井组。长期以来对香山群的研究主要集中在时代探讨上,而在其他方面较薄弱。本文以徐家圈组为主要研究对象,从浊积砂岩的碎屑颗粒类型百分含量、常量元素和微量元素等方面对其沉积时的大地构造环境进行了综合研究。结果表明:碎屑颗粒类型显示出典型的被动大陆边缘;常量元素的判别则出现了不确定性;微量元素则显示出了过渡性质。因此,香山群徐家圈组沉积时大地构造环境可能不是简单的被动大陆边缘,其物源极有可能来自被动大陆边缘、活动大陆边缘和大陆岛弧之间的带有过渡性质的源区。     

CT 双期增强扫描在甲状腺腺瘤及结节性甲状腺肿鉴别诊断中的价值?

目的：探讨 CT 双期增强扫描对甲状腺腺瘤和结节性甲状腺肿鉴别诊断中的价值。资料与方法：回顾性比较25例经手术后病理证实的甲状腺腺瘤和结节性甲状腺肿患者 CT 平扫及增强扫描结果,并进行分析。结果：25例患者共取出甲状腺结节35枚,其中甲状腺腺瘤18枚,结节性甲状腺肿17枚。腺瘤组平扫 CT 值30～60 HU,结节性甲状腺肿组平扫 CT 值25～55 HU,两者差别不明显。腺瘤组增强扫描 CT 值120～160 HU,结节性甲状腺肿组增强扫描 CT 值60～100 HU,两者有显著差异。结论：甲状腺 CT 双期增强扫描对甲状腺腺瘤和结节状甲状腺肿在鉴别诊断上可以提供重要的参考。