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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 {4. 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 74. resin column due to the fact that Amberlite IRA 74. 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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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 {4. 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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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 {4. 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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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 {4. 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： Hydrogen isotope Long-chain n-alkanes Aquatic plants Paleohydrology proxy Lake Qinghai

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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 {4. 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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Variations in chemical compositions of the eolian dust in Chinese loess Plateau over the past 2.5 Ma and chemical weathering in the Asian inland

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Science China Earth Sciences 2001年第5期44卷 403-413页

作者：陈骏安芷生刘连文季峻峰杨杰东陈旸 1. Institute of Surfacial Geochemistry State Key Laboratory of Mineral Deposit Research Department of Earth Sciences Nanjing University 210093 Nanjing China 2. state key laboratory of loess and {4. geology Chinese Academy of Sciences 710054 Xi’an China

Major and trace elements as well as strontium isotopic composition have been analyzed on the acid-insoluble (AI) phase of the loess-paleosol sequence from Luochuan, Shaanxi Province, China. Results show that the chemical composition of AI phase of loess and paleosols is distinctive to the average composition of upper continental crust (UCC), characterized by depletion of mobile elements Na, Ca and Sr. The distribution pattern of elements in AI phase reveals that initial dust, derived from a vast area of Asian inland, has suffered from Na- and Ca-removed chemical weathering compared to UCC. Some geochemical parameters (such as CIA values, Na/K, Rb/Sr and87Sr/86Sr ratios) display a regular variation and evolution, reflecting that the chemical weathering in the source region of loess deposits has decreased gradually since 2.5 Ma with the general increase of global ice volume. This coincidence reflects that the aridity of Asian inland since the quaternary is a possible regional response to the global climate change.

关键词： dust source region continental weathering acid leaching aridity global cooling

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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 {4. 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% (p4.. 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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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 {4. 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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Spatial pattern of modern sedimentation rate of Qinghai Lake and a preliminary estimate of the sediment flux

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Chinese Science Bulletin 2010年第7期55卷 621-627页

作者： XU Hai LIU XiaoYan AN ZhiSheng HOU ZhaoHua DONG JiBao LIU Bin state key laboratory of loess and {4. geology Institute of Earth Environment Chinese Academy of Sciences Shaanxi 710075 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

We investigated the spatiotemporal distribution of1 37Cs radioactivity in surface sediment of Qinghai Lake,and developed the spatial pattern of sedimentation ***1 37Cs inventory is higher near the estuary/bank area,but lower at the central *** the other hand,the average1 37Cs activity is lower near the estuary/bank area,but higher at the central *** mass accumulation rate(MAR) and the fluxes and contents of the terrestrial detritus(***2,Fe2O3,and Ti) are higher near the estuary/bank area,but lower at the central *** chemical/biogenic deposits(*** autogenic carbonates) take up higher fractions at the central *** suggest that the spatial pattern of recent sedimentation rate is dominated by the deposition of terrestrial *** average MAR(0.0337 g cm-2a-1) was estimated based on those of different cores of Qinghai Lake and was verified by a Ca mass-balance *** fluxes of total lake sediments,terrestrial detritus,and direct atmospheric deposits were also estimated.

关键词：现代沉积速率沉积物通量空间格局青海湖陆源碎屑沉积 137Cs 估算高等教育

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Characterization of MASDs of surface soils in north China and its influence on estimating dust emission

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Chinese Science Bulletin 2004年第20期49卷 2169-2176页

作者： MEI Fanmin1,2, ZHANG Xiaoye1, LU Huayu1, SHEN Zhenxing1 & WANG Yaqiang1 1. state key laboratory of loess and {4. geology, Institute of Earth Environment, Chinese Academy of Sciences, Xian 710075, China 2. Xian University of Engineering Science and Technology, Xian 71004., China state key laboratory of loess and {4. geology Institute of Earth Environment Chinese Academy of Sciences Xi''an 710075 China Xi''an University of Engineering Science and Technology Xi''an 710048 China

The micro-aggregated size distribution (MASD) of surface soil is an important parameter for modelling dust emission. However, there is no dataset of MASDs of all sur-face soil types in north China. The MASDs are here pre-sented, measured by dry sieving, for typical surface soil sam-ples, including sandy soil, gravelly sand soil, gravelly loam soil, loam soil and silt loam soil, collected from sandy deserts, Gobi deserts, oases, farmlands in steppe regions and steppe areas in north China. The MASDs of various surface soil types exhibit a combination of several log-normal distribu-tions of five separated sizes with mean mass median diame-ters (MMDs) of 90, 210, 390, 600 and 980 mm, respectively, and mean standard deviations (SDs) of 1.25, 1.4., 1.25, 1.35 and 1.25 respectively. The log-normal distributions corre-spond to very fine sand, fine sand, medium sand, coarse sand and very coarse sand population. On the basis of characteri-zation of the retrieved MASDs of various surface soil types in north China, dust emission fluxes are modelled by a dust production model (DPM model). It is shown that dust emis-sion has been significantly influenced by MASDs. Fine sand and very fine sand are always associated with the highest dust emission fluxes. Emission fluxes of the medium sand, gravelly sand soil, gravelly loam soil and loam soil are lower than those of very fine sand and fine sand, but larger than those of the coarse sand. The differences in dust emission fluxes vary among the different soil types from 101 to 103 mg·m-2·s-1. Dust emission fluxes from sandy deserts and farmlands covered with sand sheets in north China rang from 101 to 104.mg·m-2·s-1 while those from Gobi deserts, farmlands and steppes with gravelly desertification range from 101 to 102 mg·m-2· s-1. The modelled results indicate that deserts and farmlands with sand are the major dust sources in north China.

关键词：华北地区 MASDs 微块状粒度分布地面土壤粉尘排放壤土大气污染气溶胶

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