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Chemical Characteristics of Carbonaceous Aerosols During Dust Storms over Xi'an in China

Advances in Atmospheric Sciences 2008年第5期25卷 847-855页

作者：李旭祥曹军骥 Judith CHOW 韩永明李顺诚 John WATSON Department of Environmental Science and Technology Xi'an Jiaotong University Desert Research Institute Reno NV USA state key lab of loess & quaternary geology Institute of Earth EnvironmentChinese Academy of Sciences The Hong Kong Polytechnic University

Characterization of carbonaceous aerosols including CC （carbonate carbon）, OC （organic carbon）, and EC （elemental carbon） were investigated at Xi＇an, China, near Asian dust source regions in spring 2002. OC varied between 8.2 and 63.7μgm^- 3, while EC ranged between 2.4 and 17.2 μ m^-3 during the observation period. OC variations followed a similar pattern to EC and the correlation coefficient between OC and EC is 0.89 （n=31）. The average percentage of total carbon （TC, sum of CC, OC, and EC） in PM2.5 during dust storm （DS） events was 13.6%, which is lower than that during non-dust storm （NDS） periods （22.7%）. CC, OC, and EC accounted for 12.9%, 70.7%, and 16.4% of TC during DS events, respectively. The average ratio of OC/EC was 5.0 in DS events and 3.3 in NDS periods. The OC-EC correlation （R^2=0.76, n=6） was good in DS events, while it was stronger （R^2=0.90, n=25） in NDS periods. The percentage of watersoluble OC （WSOC） in TC accounted for 15.7%, and varied between 13.3% and 22.3% during DS events. The distribution of eight carbon fractions indicated that local emissions such as motor vehicle exhaust were the dominant contributors to carbonaceous particles. During DS events, soil dust dominated the chemical composition, contributing 69% to the PM2.5 mass, followed by organic matter （12.8%）, sulfate （4%）, EC （2.2%）, and chloride （1.6%）. Consequently, CC was mainly entrained by Asian dust. However, even in the atmosphere near Asian dust source regions, OC and EC in atmospheric dust were controlled by local emission rather titan the transport of Asian dust.

关键词： carbonate carbon organic carbon elemental carbon dust storm

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Aerosol-Cloud-Precipitation Interactions in WRF Model:Sensitivity to Autoconversion Parameterization

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Journal of Meteorological Research 2015年第1期29卷 72-81页

作者：解小宁刘晓东 state key laboratory of loess and quaternary geology Institute of Earth EnvironmentChinese Academy of Sciences Department of Environmental Science and Technology School of Human Settlements and Civil EngineeringXi’an Jiaotong University

Cloud-to-rain autoconversion process is an important player in aerosol loading, cloud morphology, and precipitation variations because it can modulate cloud microphysical characteristics depending on the participation of aerosols, and affects the spatio-temporal distribution and total amount of precipitation. By applying the Kessler, the Khairoutdinov-Kogan（KK）, and the Dispersion autoconversion parameterization schemes in a set of sensitivity experiments, the indirect effects of aerosols on clouds and precipitation are investigated for a deep convective cloud system in Beijing under various aerosol concentration backgrounds from 50 to 10000 cm^-3. Numerical experiments show that aerosol-induced precipitation change is strongly dependent on autoconversion parameterization schemes. For the Kessler scheme, the average cumulative precipitation is enhanced slightly with increasing aerosols, whereas surface precipitation is reduced significantly with increasing aerosols for the KK scheme. Moreover, precipitation varies non-monotonically for the Dispersion scheme, increasing with aerosols at lower concentrations and decreasing at higher *** different trends of aerosol-induced precipitation change are mainly ascribed to differences in rain water content under these three autoconversion parameterization schemes. Therefore, this study suggests that accurate parameterization of cloud microphysical processes, particularly the cloud-to-rain autoconversion process, is needed for improving the scientific understanding of aerosol-cloud-precipitation interactions.

关键词： autoconversion parameterization aerosol-cloud-precipitation interactions numerical simulation

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Climatic implications of seasonal δ13C in tree rings from Huangling of Shaanxi Province

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Chinese Science Bulletin 1996年第4期41卷 326-329页

作者：李正华刘荣谟安芷生吴祥定 state key laboratory of loess and quaternary geology Chinese Academy of Sciences Xi' an 710054 China Institute of Geograhpy Chinese Academy of SciencesBeijing 100101China

The study on stable isotopic compositions of tree rings is playing an important role in reconstructing past climatic variations on the annual scale. Recently, a higher resolution study on seasonal variation in stable isotopic compositions of tree rings is developing. Some significant results on this aspect have been obtained, and all of them seem to respond to the moisture stress of growing season. Also, the seasonal δ 13C patterns in tree

关键词： seasonal δ13C climatic implications tree ring.

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Climate and soil moisture environment during develop-ment of the fifth palaeosol in Guanzhong Plain

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Science China Earth Sciences 2008年第5期51卷 665-676页

作者： ZHAO JingBo GU Jing DU Juan College of Tourism and Environment Sciences Shaanxi Normal UniversityXi’an 710062China state key laboratory of loess and quaternary geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710075China

Based on weathering characteristics of the fifth palaeosol layer (S5) of four sections in Guanzhong Plain, the thickness of the weathered profile of the paleosol is determined to be greater than the ordi- nary soil, a weathered and leached loess layer thicker than 2 m. The distribution depth of the red argil- lans, the weathered and leached loess layer, Fe2O3, CaCO3 and Sr content under the S5 all indicate that the precipitation in Guanzhong Plain was over 900 mm at that time. The distribution depth of gravity water zone reached 4.2 m at least, and the soil moisture content was generally more than 20% within the range of 4.2 m. At that time there was sufficient soil moisture and no dried earth layer developed in Guanzhong Plain, suitable for the forest to develop. When this soil developed, the mean annual pre- cipitation was more than the annual soil moisture evaporation. The value of soil moisture balance was positive and the atmospheric precipitation could supply the underground water normally. Soil water was weak acidic in the middle and late stages when S5 developed in Guanzhong Plain. It was a kind of subtropical climate and even more humid and warmer than the northern edge of the subtropical climate zone in Guanzhong Plain when the S5 developed. At that time the subtropical climate was prevailing over the northern side and southern side of Qingling Mountains, showing the Mountains no longer to be the boundary between the subtropical zone and the temperate zone in China. The summer monsoon acted intensely and could go over Qingling Mountains frequently bring abundant precipitation.

关键词： Guanzhong Plain the fifth palaeosol weathering characteristics paleo-gravity water paleo-moisture content soil evaporation

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Late Cretaceous-Cenozoic Exhumation History of the L(u|¨)liang Mountains,North China Craton:Constraint from Fission-track Thermochronology

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Acta Geologica Sinica(English Edition) 2010年第2期84卷 296-305页

作者： LI Xiaoming SONG Yougui key laboratory of Marginal Sea geology Guangzhou Institute of Geochemistry the Chinese Academy of Sciences Guangzhou 510640 China state key laboratory of loess and quaternary geology Institute of Earth Environment the Chinese Academy of Sciences Xi＇ an 710075 China

The Lüliang Mountains, located in the North China Craton, is a relatively stable block, but it has experienced uplift and denudation since the late Mesozoic. We hence aim to explore its time and rate of the exhumation by the fission-track method. The results show that, no matter what type rocks are, the pooled ages of zircon and apatite fission-track range from 60.0 to 93.7 Ma and 28.6 to 43.3 Ma, respectively; all of the apatite fission-track length distributions are unimodal and yield a mean length of -13 μm; and the thermal history modeling results based on apatite fission-track data indicate that the time-temperature paths exhibit similar patterns and the cooling has been accelerated for each sample since the Pliocene （c.5 Ma）. Therefore, we can conclude that a successive cooling, probably involving two slow （during c.75-35Ma and 35-5Ma） and one rapid （during c.5 Ma-0 Ma） cooling, has occurred through the exhumation of the Liiliang Mountains since the late Cretaceous. The maximum exhumation is more than 5 km under a steady-state geothermal gradient of 35℃/km. Combined with the tectonic setting, this exhumation may be the resultant effect from the surrounding plate interactions, and it has been accelerated since c.5 Ma predominantly due to the India-Eurasia collision.

关键词： fission-track exhumation Liiliang Mountains late Cretaceous-Cenozoic geodynamics

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Paleomagnetic and Fission-Track Dating of a Late Cenozoic Red Earth Section in the Liupan Shan and Associated Tectonic Implications

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Journal of Earth Science 2013年第4期24卷 506-518页

作者：李云宋友桂千琳勃李小明强小科安芷生 state key laboratory of loess and quaternary geology Institute of Earth and Environment Chinese Academy ofSciences University of Chinese Academy of Sciences School of Geography South China Normal University key laboratory of Marginal Sea geology Guangzhou Institute of Geochemistry Chinese Academy of Sciences

The north-trending Liupan Shan （六盘山） is an important tectonic boundary between the Tibetan Plateau and the Ordos platform. The Late Cenozoic red earth deposits of the Liupan Shan record its tectonic history and environmental effects. In this article we report a new Late Cenozoic red earth section from an intermontane basin in the southern part of the Liupan Shan. Lithofacies analysis, paleomagnetic and fission-track chronologies, and paleocurrent analysis have been employed to identi- fy the tectonic uplift events of the Liupan Shan. Based on the age constraints of mammal fossils, the pa- leomagnetic polarity zones of the Huating （华亭） Section can be approximately correlated with the standard polarity zones that lie between C3An.2n and *** of the Geomagnetic Polar- ity Timescale; the bottom age of this section is approximately 10 Ma. Based on this and the previous studies, we infer that a tectonic event commenced in the southern Liupan Shan in this interval between 8.3 and 8.7 Ma, accompanied by a remarkable increase in sediment accumulation rate. Field observations, fission-track dating, determinations of grain-size frequency distribu- tions and the vertebrate fossils found there suggest that the red earth deposits were reworked by water and mainly transported by fluvial-alluvial processes from the adjacent area.

关键词： red earth magnetostratigraphy paleocurrent fission-track dating Liupan Shan.

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Micro-particle deposition and lobar distribution of mass flow in human upper respiratory tract model

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Chinese Science Bulletin 2011年第4期56卷 380-385页

作者： HUANG JianHua ZHANG LianZhong School of Physics Nankai University Tianjin 300071 China state key laboratory of loess and quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710075 China

A representative human upper respiratory tract model consisting of oropharyngeal and asymmetric tracheobronchial(TB) airways from the trachea(G0) to the main lobar bronchi(G2) was constructed. Laminar-to-turbulent airflow for typical inhalation modes as well as micro-particle transportation,wall deposition and mass flow to lobes was simulated using the CFX10.0 software from Ansys Inc. The numerical particle deposition efficiency of the oropharynx region and two generations(G1 and G2) of TB airways shows great agreement with the experimental data obtained from realistic casts. The particle deposition pattern indicates that inertial impaction is the primary mechanism in the human upper airway,and turbulence dispersion performs crescent influence especially for small particles. The initial positions of particles with different fates are confined to specifically concentrated zones. The particle mass distributions of five lobes are close to airflow distributions. The upper lobes receive fewer particles than lower lobes and the right middle lobe receives the least.

关键词：微观粒子呼吸道模型沉积效率质量流量 ANSYS公司人类肺航空公司

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Environmental characteristics of Mid-Holocene recorded by lacustrine sediments from Lake Daihai, north environment sensitive zone, China

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Science China Earth Sciences 2006年第9期49卷 968-981页

作者： SUN Qianli1,2, ZHOU Jie1, SHEN Ji3, CHEN Peng1,2, WU Feng1,2 & XIE Xiuping1,2 1. state key lab of loess and quaternary geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China 2. Graduate University of Chinese Academy of Sciences, Beijing 100039, China 3. Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China state key lab of loess and quaternary geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China Graduate University of Chinese Academy of Sciences Beijing China Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing China

Climate proxies, such as total organic carbon and nitrogen (TOC, TN), carbonate content (CaCO3), grain-size and pollen of the sediment core retrieved from enclosed Lake Daihai which lies in the north China environment sensitive zone are analyzed to reconstruct the environment evolution of the area based on high-resolution radiocarbon chronology. The results reveal that the TOC and TN contents of the sediments correlate well with pollen percentage and pollen flux variations during the Holocene, and both reach their peak values simultaneously at 6.7―3.5 ka BP (calendar age, 7.6―3.6 ka BP). Since 6.7 ka BP, both the CaCO3 and organic matter contents of the core have simultaneous variations, and their high values also occur during 6.7―3.5 ka BP. While during 9.0―6.7 ka BP (calendar age, 10―7.6 ka BP) relatively lower level of organic matter content and pollen flux corre- spond to the higher level of carbonate content. The above relations suggest that during 6.7―3.5 ka BP, the productivity and effective precipitation were greatly improved in the lake drainage area, and this would probably strengthen the hydrodynamic conditions, enhancing organic matter, pollen and carbonate inputs from terrestrial sources. Such processes would account for the enrichment of both organic matter and carbonate in the sediments. While during 9.0―6.7 ka BP, the lower level of or- ganic matter, pollen flux but high carbonate content show depressed productivity and declined vege- tation coverage. The higher carbonate content at this stage would have probably resulted from the higher evaporation ratio of the lake water under relatively drier climate conditions. Therefore, it is in- ferred that during 6.7―3.5 ka BP, the climate was more humid with abundant rainfalls and vegetation was more flourishing in the Lake Daihai area. This can be seen as Holocene Climate Optimum (HCO). As a result, this has evident discrepancies with the traditional notion that the HCO occurs at Early Holocene or early Mid

关键词： Lake Daihai, Mid-Holocene, lacustrine sediments, environmental characteristics.

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Soil Carbon, Nitrogen and Microbial Dynamics of Pasturelands: Impacts of Grazing Intensity and Planting Systems

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Pedosphere 2014年第3期24卷 408-416页

作者： WANG Yi DUAN Wen-Xia C.TU S.WASHBURN CHENG Lei S.HU state key laboratory of loess and quaternary geology Institute of Earth Environment Chinese Academy of Sciences Department of Plant Pathology North Carolina State University Sichuan Tourism University Department of Animal Science North Carolina State University

Management intensity critically influences the productivity and sustainability of pasture systems through modifying soil microbes, and soil carbon （C） and nutrient dynamics; however, such effects are not well understood yet ir the southeastern USA. We examined the effects of grazing intensity and grass planting system on soil C and nitrogen （N） dynamics, and microbial biomass and respiration in a long-term field experiment in Goldsboro, North Carolina, USA. A split-plot experiment was initiated in 2003 on a highly sandy soil under treatments of two grass planting systems （ryegrass rotation with sorghum-sudangrass hybrid and ryegrass seeding into a perennial bermudagrass stand） at low and high grazing densities. After 4 years of continuous treatments, soil total C and N contents across the 0 30 cm soil profile were 24.7% and 17.5% higher at the high than at the low grazing intensity, likely through promoting plant productivity and C allocation belowground as well as fecal and urinary inputs. Grass planting system effects were significant only at the low grazing intensity, with soil C, N, and microbial biomass and respiration in the top 10 cm being higher under the ryegrass/bermudagrass than under the ryegrass/sorghum-sudangrass hybrid planting systems. These results suggest that effective management could mitigate potential adverse effects of high grazing intensities on soil properties and facilitate sustainability of pastureland.

关键词： C allocation grass species microbial respiration microbial biomass pastureland sustainability plant productivity

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Tree-ring-based reconstruction of the April to September mean temperature since 1826 AD for north-central Shaanxi Province,China

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Science China Earth Sciences 2008年第8期51卷 1099-1106页

作者： CAI QiuFang LIU Yu SONG HuiMing SUN JunYan The state key laboratory of loess and quaternary geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710075China School of Human Settlements and Civil Engineering of Xi’an Jiaotong University Xi’an 710049China

Long-time series of high-resolution temperature record from Chinese loess Plateau is rare. An April-September mean temperature reconstruction (1826-2004) has been developed for the north-central Shaanxi Province, China, based on tree-ring width analysis. The reconstruction captures 39.3% (p<0.001) of the variance in the instrumental data over the calibration period from 1951 to 2002. The reconstruction shows a high temperature period of 1928-1933, which coincides with the timing of the extreme drought event in 1920s in the entire northern China. The two low temperature periods in reconstruction are 1883-1888 and 1938-1942. With the global warming, the April-September mean temperature in study area has also increased since the 1970s, but has not exceeded the temperature in 1928-1933. Besides the statistical analysis, the reconstruction is also verified by the local dryness/wetness index and other dendroclimatological results.

关键词： Huanglong Mountain Shaanxi Pinus tabulaeformis tree-ring width April-September mean temperature

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