The effect of ambient fine particulate matter (PM2.5) on respiratory diseases in China: a systematic review and meta-analysis

Stochastic Environmental Research and Risk Assessment - Only a few recent systematic reviews and meta-analysis studies have quantitatively assessed the effect of short-term exposure to ambient fine...     

Annual 30-m land use/land cover maps of China for 1980–2015 from the integration of AVHRR,MODIS and Landsat data using the BFAST algorithm

Annual land use land cover(LULC) change information at medium spatial resolution(i.e. at 30 m) is required in numerous subjects, such as biophysical modelling, land management and global change studies. Annual LULC information,however, is usually not available at continental or national scale due to reasons such as insufficient remote sensing data coverage or lack of computational capabilities. Here we integrate high temporal resolution and coarse spatial resolution satellite images(i.e., Moderate Resolution Imaging Spectroradiometer(MODIS) and Global Inventory Modelling and Mapping Studies(GIMMS) normalized difference vegetation index(NDVI)) with high spatial resolution datasets(China's Land-Use/cover Datasets(CLUDs) derived from 30-meter Landsat TM/ETM+/OLI) to generate reliable annual nominal 30 m LULC maps for the whole of China between 1980 and 2015. We also test the performance of a statistical based change detection algorithm(Breaks for Additive Seasonal and Trend), originally designed for tracking forest change, in classifying all-type LULC change.As a result, a nominal 30 m annual land use/land cover datasets(CLUD-A) from 1980 to 2015 was developed for the whole China. The mapping results were assessed with a change sample dataset, a regional annual validation sample set and a three-year China sample set. Of the detected change years, 75.61% matched the exact time of conversion within ±1 year. Annual mapping results provided a detail process of urbanization, deforestation, afforestation, water and cropland dynamics over the past 36 years. The consistent characterization of land change dynamics for China can be further used in scientific research and to support land management for policy-makers.     

晋中南中新生代构造应力场演化及其动力学分析

中生代以来,晋中南经历了多期构造应力场的作用：印支期,在华北板块南北边缘造山带的强烈挤压作用下,形成了近南北方向的水平挤压应力场;燕山期,在西太平洋古陆与亚洲大陆的碰撞、拼贴作用下,形成了北西西—南东东方向的水平挤压应力场;喜山早期,受印度板块与欧亚板块碰撞作用的影响,形成了北东—南西方向的水平挤压应力场。新第三纪以来,随着裂陷沉降作用和断陷盆地深部塑性物质上涌底辟作用的增强,晋中南构造应力场演化为以北西—南东方向近水平伸展应力场为主,并且伴随着太行山和霍山的不断隆起,在晋中南东部的沁水含煤向斜中形成了局部挤压应力场。     

Field-aligned plasma diffusive fluxes in the topside ionosphere from radio occultation measurements by CHAMP

O⁺ field-aligned diffusive velocities and fluxes in the topside ionosphere have been calculated from electron density profiles retrieved from CHAMP radio occultation (RO) measurements. The velocities and fluxes from January 2002 to December 2003 at low- and mid-latitudes have been statistically analyzed. The results show that daytime diffusive fluxes changed gradually from downward to upward as altitude increases. The largest values of the upward diffusive fluxes and velocities occurred at around ±25° geomagnetic latitude. During solstices the plasma fluxes in the winter hemisphere were larger than those in the summer hemisphere.     

The criterion of gravity wave instability induced by photochemistry in summer polar mesopause region

This paper studies the effect of photochemistry on the gravity wave instability in summer polar mesopause region. The calculation method of the effects of eddy viscosity, conductivity and eddy diffusion of chemical species on the gravity wave instability induced by photochemistry are studied. The critical wavelength of the instability is given in this paper. The influences of some parameters on it are discussed. The study shows that the gravity wave instability induced by photochemistry is sensitive to the temperature and atomic oxygen profiles.     

Ionospheric Day-to-Day Variability Around the Whole Heliosphere Interval in 2008

Ionospheric F2 peak electron densities (NmF2) measured at ten ionosonde stations have been analyzed to investigate ionospheric day-to-day variability around the Whole Heliosphere Interval (WHI) in 2008 (Day of Year (DOY) 50?–?140). The ionosonde data showed that there was significant global day-to-day variability in NmF2. This variability had 5-, 7-, 9-, 11-, 13.5-, and 16?–?21-day periodicities. At middle latitudes, the ionosphere appeared to respond directly to the solar-wind and interplanetary-magnetic-field (IMF) induced geomagnetic-activity forcing, with the day-to-day variability having the same periods as those in the solar-wind/IMF and geomagnetic activity. At the geomagnetic Equator, the ionosphere had a strong 7-day periodicity, corresponding to the same periodicity in the IMF B _z component. In the equatorial anomaly region, the ionosphere showed more complicated day-to-day variability, dominated by the 9-day periodicity. In addition, there were also periodicities of 11 days and 16?–?21 days in the ionosonde data at some stations. The ionosonde data were compared with the Coupled Magnetosphere Ionosphere Thermosphere (CMIT) simulations that were driven by the observed solar-wind and IMF data during the WHI. The CMIT simulations showed similar ionospheric daily variability seen in the data. They captured the positive and negative responses of the ionosphere at middle latitudes during the first corotating interaction region (CIR) event in the WHI. The response of the model to the second CIR event, however, was relatively weak.     

中国煤中的锗和镓

煤中的锗和镓是可利用伴生元素。我国多数煤中锗的含量处于0.5～10mg/kg之间,平均4mg/kg;煤中镓的含量处于1～20mg/kg之间,平均9mg/kg。我国云南临沧盆地发现有特大型锗矿床,锗赋存在第三纪褐煤中,含量达3000mg/kg以上,呈有机质吸附态和粘土矿物吸附态为主要赋存方式。     

中国煤中微量元素的丰度

根据现有的资料,得出中国不同地区煤中微量元素的背景值。由于分析样品分布不均和采用的测试方法各不相同,本文的数据还不能准确地代表中国煤中微量元素的平均丰度值。另外,我国不同地区、不同时代和不同地质背景下形成的煤层煤中微量元素丰度差异很大,必须从元素的资源化利用及其环境效应方面来分析元素的丰度。含量异常的元素要特别加强研究。进一步的测试和研究有助于更加全面地了解我国煤中微量元素的分布情况、地质成因及其对环境的潜在影响。     

东构造结那木拉断裂带上新世以来强烈活动的年代学证据

为揭示东喜马拉雅构造结那木拉断裂带上新世以来强烈活动特征,对采集自那木拉断裂带的三件基岩样品进行黑云母40Ar/39Ar、 磷灰石裂变径迹两种热年代学方法测年;并利用"Pecube"软件对测得年龄数据及断裂带两侧已发表年龄数据进行定量模拟计算.测试结果显示黑云母40 Ar/39 Ar年龄范围为4.44±0.71 Ma～...     

中国赴俄旅游网络关注度时空差异及成因分析

基于百度指数获取2014—2018年中国大陆31个省份对俄罗斯旅游相关关键词的网络关注度数据,采用基尼系数、首位度、季节性集中指数、地理探测器等方法,分析中国赴俄网络关注度的时空差异及其影响因素。结果表明：1）2014—2018年网络关注度与实际赴俄游客数呈正相关,5年间网络关注度增长迅猛,各月关注度则愈发均衡。2）网络关注度呈现东高西低、南高北低的特征,而网络关注度的季节性集中指数则相反;各省份网络关注度由极化分布转为相对均衡分布;各省份网络关注度的首位度不显著,北方地区最高。3）各省份网络关注度等级变化不大,东西部省份差异明显。高关注地区始终为广东、北京、上海、江苏、浙江,低关注地区以西部为主,形成甘肃-宁夏-青海-西藏连片分布的格局。4）经济发展水平、互联网普及度、国内旅游开放度是影响网络关注度空间分异的核心因素,城镇人口比重、赴俄交通便利程度、客源地夏季平均气温也起到重要作用。最后从加大互联网营销力度、推动开通直飞俄罗斯航线、开发个性化多元化旅游产品等方面提出对策建议,以期为中国赴俄旅游更好更快发展提供理论指导与实践启示。