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Sample preparation for isotopic determination of boron in clay sediments

Chinese Journal Of Geochemistry 2013年第2期32卷 203-211页

作者： ZHANG Yanling XIAO Yingkai MA Yunqi ZHUGE Qin LIU Zhiqi HE Maoyong LUO Chongguang MA Haizhou key laboratory of Salt Lake Resources and Chemistry Qinghai Institute of Salt Lakes Chinese Academy of Sciences Graduate University of Chinese Academy of Sciences state key laboratory of loess and Quaternary geology Institute of Earth Environment Chinese Academy of Sciences

The procedures of sample preparation for isotopic determination of boron in clay sediments is very cumbersome, by far, there haven't been relevant reports on that. In order to establish an effective method for sample preparation, a series of experiments were carried out. In this paper, boron in clay sediments was extracted with HCl solution and purified by two-step ion exchange method. Extracted HCl solution should be adjusted to alkalescency before passing through the Amberlite IRA 743 resin column due to the fact that Amberlite IRA 743 resin absorbs boron only from alkalescent solution. However, a mass of hydroxides of Al and Fe will be precipitated when the extracted HCl solution becomes alkalescent. Hydroxides of Al and Fe have a strong adsorption capacity for boron, which can cause boron isotope fractionation. To treat precipitated hydroxides of Al and Fe, four procedures, namely direct ion exchange (DRIE), decationizing ion exchange (DCIE), once sedimentation ion exchange (OSIE) and repeated sedimentation ion exchange (RSIE) were used and assessed. The influences of the four procedures on separation and extraction and isotopic composition of boron in experimental solutions and clay sediments were also discussed. According to the results, the DRIE, DCIE and OSIE are improper. The result of sample determination indicates that when extracting boron via RSIE, with the increase of precipitation times, there's an obvious decrease in boron content in the precipitated hydroxides while a sharp increase in recovery of boron and it is favorable for weakening the influence of boron isotope fractionation. But the process of RSIE is time consuming and it may introduce boron. It needs further research to establish a more effective sample preparation method for isotopic deter- mination of boron in clay sediments.

关键词：硼同位素组成同位素测定样品制备沉积物粘土离子交换法沉淀时间 HCl溶液

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Biological records of paleoclimate and paleoenvironment changes from Guanzhong area, Shaanxi Province during the last glacial maximum

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Chinese Science Bulletin 2000年第9期45卷 853-857页

作者： J.Head A.J.T.Jull state key laboratory of loess and Quaternary geology Xi'an 710054ChinaNSF-AMS Facility Department of PhysicsUniversity of ArizonaAZ 85721USA

We have collected a suite of Paleoloxodon naumanni-Coelodonta antiquitatis fossils from a river terrace profile between Xi’an and Xianyang cities in Guanzhong Area, Shaanxi Province. A detailed examination of the fossils, together with 14C determinations and pollen analyses, have enabled us to reconstruct preliminary features of climate and environment changes and their evolutionary processes, within the last glacial maximum (LGM): about 20 ka ago, the climate was basically cool and wet, and was favourable for the existence of Paleoloxodon naumanni-Coelodonta antiquitatis fauna. This was followed by a cold, dry phase which was no longer suitable for this type of faunal suite, causing the death of a large number of mammalian assemblages. The available evidence indicates the existence of cold-dry and cool-wet climate and environment fluctuations during the LGM. The cool-wet stage within the LGM reflects a Heinrich event occurring in the high latitude areas, proving the existence of a teleconnection

关键词： Guanzhong of Shaanxi Province Paleoloxodon naumanni-Coelodonta antiguitatis fauna last glacial maximum paleomonsoon precipitation.

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Ammonia in urban atmosphere can be substantially reduced by vehicle emission control:A case study in Shanghai, China

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Journal of Environmental Sciences 2023年第4期126卷 754-760页

作者： Can Wu Shaojun Lv Fanglin Wang Xiaodi Liu Jin Li Lang Liu Si Zhang Wei Du Shijie Liu Fan Zhang Jianjun Li Jingjing Meng Gehui Wang key Lab of Geographic Information Science of the Ministry of Education School of Geographic SciencesEast China Normal UniversityShanghai 200062China Institute for Environmental and Climate Research Jinan UniversityGuangzhou 511443China School of Public Policy and Administration Northwestern Polytechnical UniversityXi’an 710061China state key laboratory of loess and Quaternary geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China School of Environment and Planning Liaocheng UniversityLiaocheng 252000China Institute of Eco-Chongming Chenjia ZhenChongmingShanghai 202162China

To investigate the impact of emission controls on ammonia(NH_(3)) pollution in urban atmosphere, observation on NH_(3)(1 hr interval) was performed in Shanghai before, during and after the 2019 China International Import Expo (CIIE) event, along with measurements on inorganic ions, organic tracers and stable nitrogen isotope compositions of ammonium in PM_(2.5). NH_(3)during the CIIE period was 6.5±1.0μg/m^(3), which is 41% and 32% lower than that before and after the event, respectively. Such a decrease was largely ascribed to the emission controls in nonagricultural sources, of which contribution for measured NH_(3)in control phase abated by ~20% compared to that during uncontrol period. Molecular compositions of PAHs and hopanes further suggested a dominant role of the reduced vehicle emissions in the urban NH_(3)abatement during the CIIE period. Our results revealed that vehicle exhaust emission control is an effective way to mitigate NH_(3)pollution and improve air quality in Chinese urban areas.

关键词： Ammonia Non-agricultural sources Vehicle emission stable nitrogen isotope Organic tracers

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Identification of Greigite in the Pliocene Sediments of Qinghai Lake and Its Geological Significance

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Acta Geologica Sinica(English Edition) 2016年第6期90卷 2261-2262页

作者： FU Chaofeng Jan BLOEMENDAL QIANG Xiaoke Mimi J.HILL AN Zhisheng key laboratory of Western Mineral Resources and Geological Engineering Ministry of Education of ChinaChang'an University state key laboratory of loess and Quaternary geology Institute of Earth and EnvironmentCAS Geomagnetism Lab School of Environmental SciencesUniversity of Liverpool

The Qinghai Lake in North China is the largest interior plateau lake in Central Asia, and is sensitive to climate change and the environmental effects of Tibetan Plateau uplift. An almost continuous 626 m long sedimen... 详细信息

关键词： In Lake Identification of Greigite in the Pliocene Sediments of Qinghai Lake and Its Geological Significance

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Analytical Studies of the Cloud Droplet Spectral Dispersion Influence on the First Indirect Aerosol Effect

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Advances in Atmospheric Sciences 2013年第5期30卷 1313-1319页

作者：解小宁刘晓东 state key laboratory of loess and Quaternary geology Institute of Earth Environment Chinese Academy of Sciences Department of Environmental Science and Technology School of Human Settlements and Civil Engineering Xi'an Jiaotong University

Atmospheric aerosols （acting as cloud condensation nuclei） can enhance the cloud droplet number concentration and reduce the cloud droplet size, and in turn affect the cloud optical depth, as well as the cloud albedo, and thereby exert a radiative influence on climate （the first indirect aerosol effect）. In this paper, based on various relationships between cloud droplet spectral dispersion （c） and cloud droplet number concentration （Nc）, we analytically derive the corresponding expressions of the cloud radiative forcing induced by changes in the cloud droplet number concentration. Further quantitative evaluation indicates that the cloud radiative forcing induced by aerosols for the different ^-Nc relationships varies from -29.1% to 25.2%, compared to the case without considering spectral dispersion （e = 0）. Our results suggest that an accurate description of e - Nc relationships helps to reduce the uncertainty of the first indirect aerosol effect and advances our scientific understanding of aerosol-cloud-radiation interactions.

关键词： spectral dispersion cloud radiative forcing the first indirect aerosol effect

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Observational Characteristics of Cloud Radiative Effects over Three Arid Regions in the Northern Hemisphere

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Journal of Meteorological Research 2017年第4期31卷 654-664页

作者： Jiandong LI Tianhe WANG Ammara HABIB state key laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences state key laboratory of loess and Quaternary geology Institute of Earth EnvironmentChinese Academy of Sciences key laboratory for Semi-Arid Climate Change of the Ministry of Education College of Atmospheric SciencesLanzhou University

Cloud–radiation processes play an important role in regional energy budgets and surface temperature changes over arid regions. Cloud radiative effects（CREs） are used to quantitatively measure the aforementioned climatic role. This study investigates the characteristics of CREs and their temporal variations over three arid regions in central Asia（CA）, East Asia（EA）, and North America（NA）, based on recent satellite datasets. Our results show that the annual mean shortwave（SW） and net CREs（SWCRE and NCRE） over the three arid regions are weaker than those in the same latitudinal zone of the Northern Hemisphere. In most cold months（November–March）, the longwave（LW）CRE is stronger than the SWCRE over the three arid regions, leading to a positive NCRE and radiative warming in the regional atmosphere–land surface system. The cold-season mean NCRE at the top of the atmosphere（TOA） averaged over EA is 4.1 W m^-2, with a positive NCRE from November to March, and the intensity and duration of the positive NCRE is larger than that over CA and NA. The CREs over the arid regions of EA exhibit remarkable annual cycles due to the influence of the monsoon in the south. The TOA LWCRE over arid regions is closely related to the high-cloud fraction, and the SWCRE relates well to the total cloud fraction. In addition, the relationship between the SWCRE and the low-cloud fraction is good over NA because of the considerable occurrence of low cloud. Further results show that the interannual variation of TOA CREs is small over the arid regions of CA and EA, but their surface LWCREs show certain decreasing trends that correspond well to their decreasing total cloud fraction. It is suggested that combined studies of more observational cloud properties and meteorological elements are needed for indepth understanding of cloud–radiation processes over arid regions of the Northern Hemisphere.

关键词： arid region cloud fraction cloud radiative effects

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Influence of aquatic plants on the hydrogen isotope composition of sedimentary long-chain n-alkanes in the Lake Qinghai region, Qinghai-Tibet Plateau

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Science China Earth Sciences 2016年第7期59卷 1368-1377页

作者： LIU Wei Guo YANG Hong WANG Huan Ye YAO Yuan WANG Zheng CAO Yun Ning state key laboratory of loess and Quaternary geology Institute of Earth Environment Chinese Academy of Sciences School of Human Settlements and Civil Engineering Xi'an Jiaotong University laboratory for Terrestrial Environment Department of Science and Technology College of Arts and Sciences Bryant University

The hydrogen isotopic composition(δD) of leaf wax long-chain n-alkanes(C27, C29, and C31) from lacustrine sediments has been widely applied to reconstruct terrestrial paleoclimatic and paleohydrological changes. However, few studies have addressed whether the aquatic-derived n-alkanes can affect the δD values of lake sedimentary long-chain n-alkanes, which are usually regarded as a recorder of the terrestrial hydrological signals. Here we systematically investigated δD values of long-chain n-alkanes from modern aquatic plants, both near-shore and off-shore surface sediments, surrounding terrestrial plant litters, as well as river water and lake water in Lake Qinghai and its satellite lakes on the northeastern Qinghai-Tibet Plateau. Our data showed that(i) δD values of long-chain n-alkanes from aquatic plants varied from-184‰ to-132‰ for n-C27, from-183‰ to-138‰ for n-C29, and from-189‰ to-130‰ for n-C31, respectively, with no significant differences among the three n-alkanes homologues;(ii) δD values of long-chain n-alkanes from aquatic plants were generally more positive than those from surrounding terrestrial plants, possibly because that they recorded the D-enrichment of lake water in this semi-arid region;(iii) δD values of long-chain n-alkanes from surface sediments showed significant differences among the three n-alkanes homologues, due to the larger aquatic input of n-C27 to the sedimentary lipid pool than that of n-C31, and(iv) n-C27 δD values of near-shore aquatic plants and near-shore sediments are more negative than those from off-shore as a result of lower δD values of near-shore lake water. Our findings indicate that in this region(i) the offset between sedimentary n-C27 and n-C31 δD values(ΔδDC27-C31) could potentially be used to evaluate if sedimentary long-chain n-alkanes are derived from a single source;(ii) while δD values of n-C27 may be influenced by lake water hydrological changes, sedimentary n-C31 is derived predominantly from terrestrial plan

关键词：长链正构烷烃湖泊沉积物青海湖地区水生植物同位素组成西藏高原陆地植物烷烃同系物

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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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Characteristics of annual laminae gray level variations in a stalagmite from Shihua Cave, Beijing and its climatic significance (II)

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Science China Earth Sciences 2000年第5期43卷 521-533页

作者：秦小光谭明刘东生王先锋李铁英吕金波 laboratory of Speleothem and Paleoclimatology Institute of Geology Chinese Academy of Sciences Beijing 100029 China state key laboratory of loess and Quaternary geology Chinese Academy of Sciences Xi'an 710054 China Beijing Geological Survey Institute Beijing 102206 China

The annual laminae gray level variations in the stalagmite TS9501 of Shihua Cave, Beijing are studied in detail. The environmental factors influencing the laminae gray level are also analyzed. The following conditions may be necessary to the study on the lamina gray level. A) The seasonal differences of climate in the studied area are strong. B) The cave has a rapid and simple hydrological connection with the surface, such that the gray level variation is great; therefore, climatic changes can be more clearly recorded in a stalagmite. C) No water from other sources due to lateral flow adds to the seepage over the cave. D) There are more organic impurities than inorganic ones, whose content changes distinctly with time in the sample. By comparison with the modern instrumental climate records, it was found that the gray level of laminae is mainly related to the air temperature, especially the summer mean temperature. Therefore, the gray level can be used as a proxy of the air temperature. The variation

关键词： stalagmite lamina annual gray level variations temperature.

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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 in 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：放牧强度土壤微生物种植制度土壤碳牧场长期田间试验微生物生物量植物生产力

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