|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | The characteristics of atmospheric CO_2 concentration variation of four national background stations in China显示文摘Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution. | LIU LiXin, ZHOU LingXi, ZHANG XiaoChun, WEN Min, ZHANG Fang, YAO Bo & FANG ShuangXi Key Laboratory for Atmospheric Chemistry, Centre for Atmosphere Watch and Services (CAWAS), Chinese Academy of Meteoro- logical Sciences (CAMS), China Meteorological Administration (CMA), Beijing 100081, China | 2009 | Science China Earth Sciences2009，52，11： | 26 |
| 2 | Nonlinear balance constraints in 3DVAR data assimilation显示文摘In many applications of 3DVAR, the balance constraints can be considered via two main approaches: weak constraint method which adds penalty terms to the cost function; and proper defi- nition of the background error covariance matrix with non-zero cross-correlation sub-matrices. The weak constraint approach requires determining the weighting matrices of the penalty terms. The background error covariance approach does not require determining those additional weighting ma- trices. However, it is only applicable to those linear or linearized balance constraints. A novel ap- proach is proposed based on the background error covariance approach by generalizing the so-called Derber-Bouttier formulation. An assimilation experiment of estimating temperature and salinity from the sea surface dynamic height observation is given to illustrate the proposed treatments of nonlinear balance constraints. | ZHU Jiang YAN Changxiang | 2006 | Science China Earth Sciences2006，49，3： | 24 |
| 3 | 面向舆情事件的子话题标签生成模型ET-TAG显示文摘关于舆情事件的新闻数据是纷繁复杂的.即便是关于同一舆情事件的新闻数据,往往包含有不同的子话题(事件的不同侧面).因此,如何生成能够准确描述事件子话题含义的标签对深入分析舆情事件(包括掌握事件热点、监测发展走向等)具有重要意义.事件子话题标签的生成通常包括两个关键步骤:首先发现子话题,然后依据每个子话题的关键词或文档内容生成描述该子话题的有效标签.传统方法在发现话题时多采用聚类或分类的方法,它们将同一个话题的文档整合到一个簇中.然而,由于隶属同一事件的文档具有很强的相似性,现有方法难以度量他们之间的距离,因此无法应用于发现事件子话题这一任务.此外,在为子话题生成标签时,传统的方法通常通过抽取来实现.此类方法所生成标签的准确性无法保证.为此,该文提出了一种基于PLSA with Background Language并结合关键词聚类发现事件内部子话题,进而基于维基百科等知识库生成事件子话题标签的模型ET-TAG.在多类舆情事件数据集上的实验结果表明,ET-TAG算法相比K-means和LDA等已有子话题发现方法具有更好的性能;从子话题标签生成角度而言,ET-TAG生成的标签相对于传统方法也具有更好的准确性和概括性.该文最后将ET-TAG算法生成的子话题标签用于事件的对比和追踪,结果表明通过子话题标签可以发现事件共性,并反映事件子话题热度的变化趋势. | 周楠 杜攀 靳小龙 刘悦 程学旗 | 2018 | 计算机学报2018，41，7： | 18 |
| 4 | Global aridification in the second half of the 20th century and its relationship to large-scale climate background显示文摘The variation in surface wetness index (SWI), which was derived from global gridded monthly precipi- tation and monthly mean surface air temperature datasets of Climatic Research Unit (CRU), from 1951― 2002 over global land was analyzed in this paper. The characteristics of the SWI variation in global continents, such as North America, South America, Eurasia, Africa, and Australia, were compared. In addition, the correlation between the SWI variation of each continent (or across the globe) and the large-scale background closely related to SST variations, which affects climate change, was analyzed. The results indicate that the SWI variation shows distinct regional characteristics in the second half of the 20th century under global warming. A drying trend in the last 52 years occurred in Africa, Eurasia, Australia and South America, most obviously in Africa and Eurasia. North America shows a wetting trend after 1976. A 30-year period of dry-wet oscillation is found in South America and Australia; the latest is in a drying period in two regions. The results also revealed that global warming has changed the dry-wet pattern of the global land. South America and Australia have a drying trend despite in- creases in precipitation. This indicates that increases in surface air temperature cannot be ignored in aridification studies. Global dry-wet variation is closely related to large-scale SST variations: the drying trend in Africa and Eurasia and the wetting trend in North America are correlated with Pacific Decadal Oscillation (PDO); the interdecadal oscillation of SWI in South America and Australia is consistent with the interdecadal variation in Southern Oscillation Index (SOI). | MA ZhuGuo FU CongBin | 2007 | Science China Earth Sciences2007，50，5： | 17 |
| 5 | The Background Features and Formation of Chemical Elements of Groundwater in the Region of the Middle and Lower Reaches of the Yangtze River显示文摘The paper deals with the background features, formation and distribution of the chemical el-ements K, Na, Ca, Mg, Si, Fe, Mn, Cr, Ni,V, Co, Ti, Mo, Cu, Pb, Zn, As, Hg, Cd, Be, Li, Sr, B,F, Cl, Br and I in the groundwater in the region of the middle and lower reaches of the YangtzeRiver and their relations to the composition of the water-bearing media, properties of the overly-ing rocks and soils, redox environment, and groundwater flow condition, mineralization and pHof groundwater. | Zeng Zhaohua Institute of Environmental Geology,Jiangxi Bureau of Geology and Mineral Resources, Nanchang, Jiangxi Shang Ruoyun | 1997 | Acta Geologica Sinica(English Edition)1997，71，1： | 17 |
| 6 | Severe Drought Events as Revealed in the Climate Records of China and Their Temperature Situations over the Last 1000 Years显示文摘The total 15 severe droughts are discovered with the aid of the 'Retrieval System of Chinese HistoricalClimate Records' for the last 1000 years. The droughts are extensive to envelope more than 4 provinces andpersistent to cover 3 yr or more, and their severity is equivalent to or in excess of that in the 1930s in China.According to the documentary records and restorations it can be inferred that most droughts are more severethan those in the last 50 years. The 15 droughts may either occur warm or in a cold climate background,with 11 of the 15 cases in the cold phase. This indicates the difference in climate correspondence betweenChina and northern America, showing the severity of the events in China to be in a cold instead of a warmclimate situation. That is likely to relate to the monsoon climate in eastern Asia. | 张德二 | 2005 | Acta meteorologica Sinica2005，19，4： | 15 |
| 7 | An improved binarization algorithm of wood image defect segmentation based on non-uniform background显示文摘In this study,an image binarization optimization algorithm,based on local threshold algorithms,is proposed because global and traditional local threshold segmentation algorithms cannot effectively address the problems of nonuniform backgrounds of wood defect images.The proposed algorithm calculates the threshold by the mean,standard deviation and the extreme value of the window.The results indicate that this modified algorithm enhances the image segmentation for wood defect images on a complex background,which is much superior to the global threshold algorithm and the Bernsen algorithm,and slightly better than the Niblack algorithm and Sauvola algorithm.Compared with similar models,the algorithm proposed in this paper has higher segmentation accuracy,as high as 92.6%for wood defect images with a complex background. | Wei Luo Liping Sun | 2019 | Journal of Forestry Research2019，30，4： | 13 |
| 8 | Oscillation characteristics of summer precipitation in the Huaihe River valley and relevant climate background显示文摘Based on the summer precipitation data from the Huaihe River valley and the middle and lower reaches of the Yangtze River from 1922 to 2007,we analyzed the interannual and interdecadal oscillation and probability distribution characteristics of summer precipitation in the Huaihe River valley during the same period,using the wavelet transform and generalized extreme distribution methods.Whereby,we studied the climate background of East Asia Summer Monsoon (EASM),Sea Surface Temperature (SST),East Asia telecorrelation circulation,and their relationship with the interannual and interdecadal oscillation of summer precipitation in the Huaihe River valley.We further compared the difference of interdecadal oscillation of summer precipitation and the relevant climate background between the Huaihe River valley and the middle and lower reaches of the Yangtze River.The results show that:1) The intensity change of quasi-biennial oscillation (QBO) of summer precipitation in the Huaihe River valley is consistent with that of interdecadal oscillation.The summer precipitation in the Huaihe River valley has been more than normal since the end of the 1990s,and the QBO is very significant.Meanwhile,the probability of occurrence of extreme heavy rainfall increased obviously.2) The interdecadal oscillation of summer precipitation in the Huaihe River valley has a close relationship with the Pacific Decadal Oscillation (PDO) and interdecadal oscillation of EASM.When PDO is in the cold phase and EASM weakens,the summer precipitation will be greater than normal.3) QBO of summer precipitation in the Huaihe River valley is mainly controlled by that of EASM,and it has a relationship with a circulation pattern of 'positive-negative-positive' from the high to the low latitudes in East Asia.4) There is interdecadal phase difference in summer precipitation between the Huaihe River valley and the middle and the lower reaches of the Yangtze River,which is mainly related to the intensity and position of West Pacific subtropical high. | FengYing Wei Ting Zhang | 2010 | Science China Earth Sciences2010，53，2： | 13 |
| 9 | Unfolding analysis of LaBr3:Ce gamma spectrum with a detector response matrix constructing algorithm based on energy resolution calibration显示文摘With respect to the gamma spectrum, the energy resolution improves with increase in energy. The counts of full energy peak change with energy, and this approximately complies with the Gaussian distribution. This study mainly examines a method to deconvolve the LaBr_3:Ce gamma spectrum with a detector response matrix constructing algorithm based on energy resolution calibration.In the algorithm, the full width at half maximum(FWHM)of full energy peak was calculated by the cubic spline interpolation algorithm and calibrated by a square root of a quadratic function that changes with the energy. Additionally, the detector response matrix was constructed to deconvolve the gamma spectrum. Furthermore, an improved SNIP algorithm was proposed to eliminate the background. In the experiment, several independent peaks of ^(152)Eu,^(137)Cs, and ^(60)Co sources were detected by a LaBr_3:Ce scintillator that were selected to calibrate the energy resolution. The Boosted Gold algorithm was applied to deconvolve the gamma spectrum. The results showed that the peak position difference between the experiment and the deconvolution was within ± 2 channels and the relative error of peak area was approximately within 0.96–6.74%. Finally, a ^(133) Ba spectrum was deconvolved to verify the efficiency and accuracy of the algorithm in unfolding the overlapped peaks. | Rui Shi Xian-Guo Tuo Huai-Liang Li Yang-Yang Xu Fan-Rong Shi Jian-Bo Yang Yong Luo | 2018 | Nuclear Science and Techniques2018，29，1： | 11 |
| 10 | A comparison of the biological,geological events and environmental backgrounds between the Neoproterozoic-Cambrian and Permian-Triassic transitions显示文摘The Neoproterozoic-Cambrian(N-C) and Permian-Triassic(P-T) transitions have been regarded the two most critical transitions in earth history because of the explosive biological radiation in the early Cambrian(the Cambrian Explosion) and the largest mass extinction at the end-Permian.Previous studies suggest that these two critical transitions showed certain comparability in major evolutionary events.In other words,a series of biological,geological,and geochemical events that had happened in the N-C transition occurred repeatedly during the P-T transition.Those events included continental re-configuration related to the deep mantle dynamics,global-scale glaciations,large C-,Sr-,and S-isotope perturbations indicating atmospheric and oceanic changes,abnormal precipitation of carbonates,and associated multiple biological radiations and mass extinctions.The coupling of those events in both N-C and P-T transitions suggests that deep mantle dynamics could be a primary mechanism driving dramatic changes of environment on the earth's surface,which in turn caused major biological re-organizations.A detailed comparison of those events during the two critical transitions indicates that despite their general comparability,significant differences do exist in magnitude,duration,and frequency.The supercontinent Rodinia began to rift before the Snowball Earth time.By contrast,the supercontinent Pangea entered the dispersal stage after the greatest glaciation from the Late Carboniferous to Cisuralian.Quantitative data and qualitative analyses of different fossil groups show a more profound mass extinction during the N-C transition than at the end-Permian in terms of ecosystem disruption.This is indicated by the disappearance of the whole Ediacaran biota at the N-C boundary.The subsequent appearances of many new complex animals at phylum level in the early Cambrian mark the establishment of a brand new ecosystem.However,the end-Permian mass extinction is manifested mainly by the extinction of many different taxa at class and order levels.Although it caused the extinction of 95% of marine species and 75% of terrestrial species as well as complete cessation of coal and reef deposits after the mass extinction,this high-level biological re-organization still occurred within an established ecosystem,however drastic it may seem.Survived or Lazarus taxa re-occupied the existing ecospace in a relatively short duration after the end-Permian mass extinction.C-isotope excursions display large perturbations during both transitions,yet also in different magnitudes and frequencies,which suggest different atmospheric and oceanic conditions.The recurrent geological and geochemical events as well as the coupled major biological turnovers during the two transitions provide new clues to understanding the interplays among the earth-life system.Thus,it is essential to carry out multidisciplinary studies from the deep internal system to the surface of the Earth as a whole in order to unravel the interactions of different spheres of the earth. | ShuZhong Shen MaoYan Zhu XiangDong Wang GuoXiang Li ChangQun Cao Hua Zhang | 2010 | Science China Earth Sciences2010，53，12： | 9 |
| 11 | THERMAL INFRARED ANOMALIES UNDER THE NON-TEMPERATURE-INCREMENT BACKGROUND AND THE MECHANISM DISCUSSION显示文摘Only in the range of abnormal area determined can we analyze the relation of the surface temperature variation at a single station with earthquakes. Namely, we must adopt the combined method of the plan and time-temperature curves to study the ground temperatureincrease anomalies. Altogether 15 earthquakes of M>5.0 which occurred in the mainland | 强祖基 徐秀登 赁常恭 | 1991 | Chinese Science Bulletin1991，36，22： | 9 |
| 12 | CO_2 background concentration in the atmosphere over the Chinese mainland显示文摘Based on the long-term monitoring data on CO2 concentration, variation trend and characteristics of CO2 background concentration in the atmosphere over the Chinese mainland are analyzed. Results show that the increasing trend of CO2 background concentration in the atmosphere over the Chinese mainland has appeared during the period of 1991-2000. The average annual CO2 growth increment is 1.59μL/L, and the average annual CO2 growth rate is 0.44%. Distinct seasonal variations of CO2 background concentration are observed, and the averaged amplitude of CO2 seasonal variations is 10.35μL/L. Regional variation characteristics of CO2 background concentration in the atmosphere and possible impact of human activities on these variations over the Chinese mainland are discussed as well. | WANG Gengchen, WEN Yupu, KONG Qinxin, REN Lixin & WANG MulinInstitute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China Academy of Meteorological Sciences, China Meteorological Administration, Beijing 100086, China | 2002 | Chinese Science Bulletin2002，47，14： | 9 |
| 13 | Systematic distortion in cosmic microwave background maps显示文摘To minimize instrumentally the induced systematic errors,cosmic microwave background(CMB)anisotropy experiments measure temperature differences across the sky using pairs of horn antennas, temperature map is recovered from temperature difference obtained in sky survey through a map-making procedure.To inspect and calibrate residual systematic errors in the recovered temperature maps is important as most previous studies of cosmology are based on these maps.By analyzing pixel-ring coupling and latitude dependence of CMB temperatures,we find notable systematic devia- tion from CMB Gaussianity in released Wilkinson Microwave Anisotropy Probe(WMAP)maps.The detected deviation cannot be explained by the best-fit LCDM cosmological model at a confidence level above 99%and cannot be ignored for a precision cosmology study. | LIU Hao 1,3 &LI TiPei 1,2 1Key Laboratory of Particle Astrophysics,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China 2Center for Astrophysics,Tsinghua University,Beijing 100084,China 3 Graduate University of Chinese Academy of Sciences,Beijing 100049,China | 2009 | Science China(Physics,Mechanics & Astronomy)2009，52，5： | 8 |
| 14 | Zircon U-Pb dating and geochemical study of the Xianggou granite in the Ma'anqiao gold deposit and its relationship with gold mineralization显示文摘Single zircon LA-ICP-MS U-Pb dating and lithogeochemical studies have been performed on the Xianggou monzonitic granitic porphyry outcropped in the Ma'anqiao gold deposit.A weighted average U-Pb age of 242.0±0.8 Ma for Xianggou monzonitic porphyry has been obtained.This corresponds with the conclusions of previous studies indicating a syn-orogenic age (242±21 Ma) of the Qinling Orogenic Belt,suggesting that the formation of the Xianggou granite should be associated with the collisional event of the North China Plate and the Yangtze Plate in the Indosinian period.The Xianggou granite is characterized by the high silicon and alkali of high K calc-alkaline series granites.It is rich in Al (Al2O3=14.49%-15.61%) and Sr (457.10-630.82 ppm),poor in Y (<16 ppm) and HREE (Yb<0.45 ppm),and exhibits high ratios of Sr/Y (76.24-97.34) and (La/Yb)N (29.65-46.10),as well as strongly fractionated REE patterns.These geochemical characteristics suggest the Xianggou granite can be classified as C-type adakitic rock.The initial Sr isotope ratios for the Xianggou granite vary from 0.70642 to 0.70668,εNd(t) values from -4.54 to -3.98,and TDM values from 1152 Ma to 1220 Ma.The low εNd(t) and ISr and high TDM values,as well as Na2O/K2O ratios of the Xianggou granite are close to 1 (Na2O/K2O=0.95-1.10),indicating that it is not an I-type adakite formed by partial melting of the subducting oceanic crust,nor adakitic rock formed by melting of the underplated basaltic lower crust,but the product of partial melting of the nonunderplated basaltic thickened lower crust.Zircons from the Xianggou pluton have a homogeneous Hf isotopic composition with negative εHf(t) values (between -9.7 and -5.9,with an average of -6.9),indicating that the rock-forming materials were mostly extracted from the ancient crust,not from the depleted mantle.The Xianggou monzonitic granitic porphyry is rich in LILE and LREE and depleted in HSFE,HREE and Y;the composition of trace element and REE are similar to those of the syn-collisional granites.The geological and geochemical characteristics of the Xianggou granite reveal that it was a product of partial melting of the basaltic rocks from the thickened lower crust,triggered by continental collision,which occurred in the geodynamic background of continental-continental collision and shearing within the crust.The Xianggou granite was intruded in the compressive orogenic environment 242 Ma ago,but the gold mineralization occurred in the transitional environment of compression to extension around 170 Ma ago,lagging behind the intrusive age of the Xianggou granite by about 70 Ma.Meanwhile,the distribution of trace elements and REEs of the Xianggou monzonitic granitic porphyry is distinct from that of ores,suggesting the absence of direct genetic relationship between the Xianggou granite and gold mineralization.In contrast,the relatively high ore-forming elemental content of the Xianggou monzonitic granitic porphyry is due to the rock having experienced Au-bearing hydrothermal alteration.From the view of gold mineralization,considering the intrusive age,structural deformation,as well as alteration of the granite,we can conclude that the Xianggou pluton was a pre-ore-intrusion,whose intrusive age of 242 Ma constrains the lower time limit of gold metallogenesis.Following the intrusive event of the syn-collisional granitic porphyry and the intensively brittle-ductile shear deformation,large-scale fluid activity and gold mineralization took place. | LEE Ben | 2010 | Science China Earth Sciences2010，53，2： | 8 |
| 15 | Study on the proposed environmental guidelines for Cd, Hg, Pb and As in soil of China显示文摘This paper deals with the soil-environmental standard. According to the current situation of researching on the soil-environmental quality guideline at home and abroad, and on the basis of the foundations and principles of enacting the soil-environmental standard, the soil environment quality guideline values of Hg, Cd, Pb and As were suggested. | Wu Yanyu, Tian Junliang Zhou QixingInstitute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110015, ChinaNorthwest Institute of Water and Soil Conservation, Chinese Academy of Sciences, Shaanxi 712100, China | 1992 | Journal of Environmental Sciences1992，4，1： | 7 |
| 16 | OBSERVATION AND INVESTIGATION OF VARIABILITIES OF BASELINE CO_2 CONCENTRATION OVER WALIGUAN MOUNTAIN IN QINGHAI PROVINCE OF CHINA显示文摘In-situ measurement of atmospheric CO2 was made at the top of the Waliguan Mountain(36°17′N,100°54′E,3816m asl).where the air is not directly affected by the local anthropogenic and natural sources,by using a nondispersiveinfrared(NDIR)analyzer and following the procedures proposed by WMO.The CO2 in the flask samples collected onthe mountain was also analyzed in a laboratory.The measurements uncover the daily,monthly and seasonal variabilitiesand the baseline level of the CO2 in the air over the“clean”area of Chinese hinterland.Results suggest that theCO2 concentration over the East Asia continent has evident periodical variation,similar to that of global distribution.In1992,an annual mean baseline CO2 concentration of 356.4 ppm over the continent was obtained.The annual mean val-ue was 357.2 ppm for 1993.Some relationships between the CO2 concentration at Waliguan and the weather conditions,especially,wind speed and direction are found through the observation. | 温玉璞 邵志清 徐晓斌 季秉法 朱庆斌 | 1994 | Acta meteorologica Sinica1994，8，3： | 7 |
| 17 | Morphology,composition,and sources of individual aerosol particles at a regional background site of the YRD,China显示文摘Aerosol samples were collected at Lin'an, a background site of Yangtze River Delta(YRD).Morphology, size, composition, and mixing state of individual aerosol particles were characterized by transmission electron microscopy(TEM) coupled with energy dispersive X-ray spectroscopy(EDS), and the soluble ions of PM_(1.0) were studied by aerosol mass spectrometer(AMS). The daily average AMS mass concentrations of sulfate, nitrate, and ammonium were about 5.8, 8.6, and 5.6 μg/m^3, respectively. Individual aerosol particles were classified into seven types: S-rich, K-rich, organic matter(OM), soot, fly ash, metal, and mineral. S-rich particles were dominant in all size bins, and 51%(by number) of S-rich particles were internally mixed with other particles. The fraction of organic coating particles was 13.7% in morning, 25.2% in afternoon, and 11% in evening, suggesting that the strong photochemical process during afternoon produced more secondary organic aerosols(SOA) on the surface of inorganic particles. Fly ash and metal particles were abundant during the day, suggesting the influence of emissions from coal-fired power plants and steel plants. The results indicate that the intense industrial emissions in the YRD significantly transported to the background areas. PM_(2.5) concentration may be lower in background air than in urban air but complex mixing state of aerosol particles indicates that the long-range transported particles substantially influenced the background air quality. | Liang Xu A.P.Lingaswamy Yinxiao Zhang Lei Liu Yuanyuan Wang Jian Zhang Qianli Ma Weijun Li | 2019 | Journal of Environmental Sciences2019，31，3： | 6 |
| 18 | Comparison of Ozone and PM2.5 Concentrations over Urban,Suburban,and Background Sites in China显示文摘Surface ozone(O3)and fine particulate matter(PM2.5)are dominant air pollutants in China.Concentrations of these pollutants can show significant differences between urban and nonurban areas.However,such contrast has never been explored on the country level.This study investigates the spatiotemporal characteristics of urban-to-suburban and urban-tobackground difference for O3(Δ[O3])and PM2.5(Δ[PM2.5])concentrations in China using monitoring data from 1171 urban,110 suburban,and 15 background sites built by the China National Environmental Monitoring Center(CNEMC).On the annual mean basis,the urban-to-suburbanΔ[O3]is−3.7 ppbv in Beijing-Tianjin-Hebei,1.0 ppbv in the Yangtze River Delta,−3.5 ppbv in the Pearl River Delta,and−3.8 ppbv in the Sichuan Basin.On the contrary,the urban-to-suburbanΔ[PM2.5]is 15.8,−0.3,3.5 and 2.4μg m^−3 in those areas,respectively.The urban-to-suburban contrast is more significant in winter for bothΔ[O3]andΔ[PM2.5].In eastern China,urban-to-background differences are also moderate during summer,with−5.1 to 6.8 ppbv forΔ[O3]and−0.1 to 22.5μg m^−3 forΔ[PM2.5].However,such contrasts are much larger in winter,with−22.2 to 5.5 ppbv forΔ[O3]and 3.1 to 82.3μg m^−3 forΔ[PM2.5].Since the urban region accounts for only 2%of the whole country’s area,the urban-dominant air quality data from the CNEMC network may overestimate winter[PM2.5]but underestimate winter[O3]over the vast domain of China.The study suggests that the CNEMC monitoring data should be used with caution for evaluating chemical models and assessing ecosystem health,which require more data outside urban areas. | Lan GAO Xu YUE Xiaoyan MENG Li DU Yadong LEI Chenguang TIAN Liang QIU | 2020 | Advances in Atmospheric Sciences2020，37，12： | 5 |
| 19 | Study on cosmogenic activation in germanium detectors for future tonne-scale CDEX experiment显示文摘A study on cosmogenic activation in germanium was carried out to evaluate the cosmogenic background level of natural and ^(70)Ge depleted germanium detectors. The production rates of long-lived radionuclides were calculated with Geant4 and CRY.Results were validated by comparing the simulated and experimental spectra of CDEX-1B detector. Based on the validated codes, the cosmogenic background level was predicted for further tonne-scale CDEX experiment. The suppression of cosmogenic background level could be achieved by underground germanium crystal growth and high-purity germanium detector fabrication to reach the sensitivity requirement for direct detection of dark matter. With the low cosmogenic background, new physics channels,such as solar neutrino research and neutrinoless double-beta decay experiments, were opened and the corresponding simulations and evaluations were carried out. | JingLu Ma Qian Yue ShinTed Lin Henry Tsz-King Wong JinWei Hu LiPing Jia Hao Jiang Jin Li ShuKui Liu ZhongZhi Liu Hao Ma WeiYou Tang Yang Tian Li Wang Qing Wang Yi Wang LiTao Yang Zhi Zeng | 2019 | Science China(Physics,Mechanics & Astronomy)2019，62，1： | 5 |
| 20 | Geological characteristics,metallogenic background,and genesis of the Tongyu VHMS copper deposit in the west part of the North Qinling,Shaanxi Province显示文摘The Tongyu volcanic-hosted massive sulfide(VHMS) copper deposit is located in the west part of the North Qinling(NQL),Shaanxi Province.Here we report geological features and trace elemental characteristics of ores,mineralized rocks,and volcanic host rocks of this deposit.We also conducted in situ zircon U-Pb and Lu-Hf LA-ICP-MS dating and lithogeochemical study of the Meigou granodiorite,which is intruded in the south of the Tongyu mining district.It is inferred that the volcanic host rocks of the Tongyu Cu deposit belong to calc-alkaline island arc volcanic rocks,and the volcanic host rocks and the ore-forming materials share common material sources.During subduction of the Paleo-Qinling oceanic slab at around 472 Ma,high oxygen-fugacity aqueous fluid released by dehydration reaction of the subducting slab rose into the mantle wedge,leached Cu and other metal elements,and triggered partial melting of the mantle wedge.Associated with the ore-forming materials,the arc calc-alkaline magmas erupted and formed the Tongyu VHMS deposit.The weighted average zircon U-Pb age of the Meigou granodiorite is 439.3±3 Ma,suggesting its genesis is associated with the subduction event of the Paleo-Qinling oceanic plate around 440 Ma.In terms of the granitoid's geochemical characteristics,the Mg#,Ni,and Cr contents are high.REE show strongly fractionated patterns with unobvious Eu anomalies.Sr contents are high while Y contents are low,resulting in high Sr/Y ratios.Two-stage zircon Hf model ages mostly range between 908 and 723 Ma,with εHf(t)>0.Therefore,we classify Meigou granodiorite as island arc granite with adakitic geochemical features.It was generated by interaction between mantle wedge and melt produced by partial melting of the subducted basaltic slab of the Paleo-Qinling Ocean.The Tongyu VHMS deposit was formed in the island arc tectonic setting during Ordovician-Silurian between 439.3±3 Ma and 472±11 Ma.The volcanic exhalation-sedimentation,which was contemporaneous with the submarine volcanics,produced the primary mineralization of the Tongyu Cu deposit.Afterward,the ore bodies and host rocks were reworked and overprinted intensively by structures corresponding with the overall collisional orogenic process of the Qinling Orogenic Belt during the Indosinian period.In contrast to classic VHMS deposits such as the Kuroko deposit in Japan,the Tongyu Cu deposit possesses the dual characteristics of island arc volcanic exhalation and sedimentation as well as structural reworking and overprinting.Therefore,the Tongyu VHMS Cu deposit is a volcanic exhalation and sedimentation-structural reworking and overprinting type deposit. | Ben Lee LaiMin Zhu GuoWei Zhang Bo Guo HuJun Gong AnPing Yao | 2010 | Science China Earth Sciences2010，53，10： | 5 |
您所在的机构暂未开通此部分的功能，请联系管理员