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An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

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Science china Chemistry 2006年第5期49卷 454-465页

作者： xiAO Yingkai1,2.LI Shizhen1,WEI Haizhen1,SUN Aide1,ZHOU Weijian2.& LIU Weiguo2.1. Qinghai {3. of Salt Lakes,{1. {2. of {3.,xining 810008,china 2. State Key Laboratory of Loess and Quaternary Geology,{3. of earth environment,{1. {2. of {3.,xi’an {1.},china 1. Qinghai institute of Salt Lakes Chinese Academy of Sciences Xining 810008 China 2. State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China

Inorganic calcium carbonate precipitation from natural seawater and salinewater at various pH values was carried out experimentally. The results show the clear positiverelationships between boron concentration and δ^(1.)B of inorganic calcium carbonate with the pH ofnatural seawater and saline water. However, the variations of boron isotopic fractionation betweeninorganic calcite and seawater/saline water with pH are inconsistent with the hypothesis thatB(OH)_4^- is the dominant species incorporated into the biogenic calcite structure. The isotopicfractionation factors a between synthetic calcium carbonate precipitate and parent solutionsincrease systematically as pH increases, from 0.9884 at pH 7.60 to 1.0072.at pH 8.60 for seawaterand from 0.982. at pH 7.60 to 1.01.8 at pH 8.75 for saline water. An unusual boron isotopicfractionation factor of larger than 1.in synthetic calcium carbonate precipitated fromseawater/saline water at higher pH is observed, which implies that a substantial amount of theisotopically heavier B(OH)_3.species must be incorporated preferentially into synthetic inorganiccarbonate. The results propose that the incorporation of B(OH)_3.is attributed to the formation ofMg(OH)_2.at higher pH of calcifying microenvironment during the synthetic calcium carbonateprecipitation. The preliminary experiment of Mg(OH)_2.precipitated from artificial seawater showsthat heavier ^(1.)B is enriched in Mg(OH)_2.precipitation, which suggests that isotopically heavierB(OH)_3.species incorporated preferentially into Mg(OH)_2.precipitation. This result cannot beapplied to explain the boron isotopic fractionation of marine bio-carbonate because of thepossibility that the unusual environment in this study appears in formation of marine bio-carbonateis infinitesimal. We, however, must pay more attention to this phenomenon observed in this study,which accidentally appears in especially natural environment.

关键词： boron, isotopic fractionation, calcium carbonate precipitate, seawater, saline water.

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Human remains and the environment of Early Pleistocene in the Nihewan Basin

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Science china {1. {2. 2004年第5期47卷 437-444页

作者： CAI Baoquan1.& LI qiang2.1. Department of History, xiamen University, Fujian 3.1.05,{1. 2. {2. of Vertebrate Palaeontology and Palaeoanthropology,{3., Beijing 1.0044,{1. xiamen Univ Dept Hist Fujian 361005 Peoples R China chinese Acad Sci Inst Vertebrate Paleontol & Paleoanthropol Beijing 100044 Peoples R China

A new Early Pleistocene Paleolithic site was found in July 2.01.in the Nihewan Ba-sin, Hebei Province. Totally 500 mammal specimens assigned to 2.0}species and 5 lithic artifacts were collected. The coexistence of Allophaiomys deucalion, Borsodia chinensis and Yangia tingi provides important evidence of chronology. On the basis of the comparison of mammalian fauna, the date of Paleolithic artifacts is probably earlier than 1.8 MaBP, possibly 2.0 MaBP. This is the earliest evidence of hominid activity found so far in North china. The hominid at that time in the Nihewan Basin lived in an {1. of arid grasslands with scattered trees of temperate zone. This discovery is significant to the study of human origin and cultural development.

关键词： human remains, environment, Early Pleistocene, Nihewan.

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Distributions of fatty acids in a stalagmite related to paleoclimate change at Qingjiang in Hubei,southern china

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Science china {1. {2. 2005年第9期48卷 1463-1469页

作者： xiE Shucheng1,HUANG Junhua1,WANG Hongmei2.YI Yi1,HU Chaoyong1, CAI Yanjun3.& CHENG Hai4 1. Faculty of earth Science,{1. University of Geo{2.,Wuhan 43.074,{1. 2. School of environmental Studies,{1. University of Geo{2.,Wuhan 43.074,{1. 3. SKLLQG,institute of earth environment,{1.} {1.} of {2.,xi’an {1.},{1. 4. Department of Geology and Geophysics,University of Minnesota,MN55455,USA 1. Faculty of earth Science China University of Geosciences 430074 Wuhan China 2. School of environmental Studies China University of Geosciences 430074 Wuhan China 3. SKLLQG Institute of Earth Environment Chinese Academy of Sciences 710075 Xi’an China 4. Department of Geology and Geophysics University of Minnesota 55455 MN USA

Fatty acids extracted from a subtropical stalagmite at Qingjiang in Southern china’s Hubei Province were analysed using gas chromatography-mass spectrometry. These n-alkanoic acids range from C1. to C2. in carbon number, maximizing at C1., with a second dominance at C2.. In contrast to the stalagmite analysed, the overlying soils are characterized by the dominance of heavy-molecular-weight homologues (>C2.). The n-fatty acids in the stalagmite were proposed to be contributed by both the soil ecosystems and the microbes harboring in the percolating water and the cave. The ratios of unsaturated to saturated n-fatty acids (C1.:1./C1.:0, C1.:1.C1.:0) appear to show trends comparable with the oxygen isotope records of the stalagmite carbonate, with enhanced values associated with the cold episode such as Heinrich event 1. This paleoclimate-dependent record of the n-fatty acids might reflect microbial changes in physiology and activity in response to the temperature. This record shows somewhat difference from the previous paleoclimate signal extracted from n-alkanols and n-alkan-2.ones of the same stalagmite. The acid record fails to document the well-known Younger Dryas event which was effectively shown by the latter two biomarkers derived from soil ecosystems. This discrepancy might result from the changing biogeochemical impact on different lipid fractions as well as the varied organism populations in different ecosystems.

关键词： biomarker, ecosystem, microbe, speleothem, paleoclimate, Quaternary.

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Paleoclimatic application of spectral parameters to the eolian red clay of the Jianzha Basin,northeastern margin of the Tibetan Plateau

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Science china {1. {2. 2024年第6期67卷 1952-1966页

作者： Chaofeng FU Ju’e TIAN xinwen XU Yougui SONG Jun ZUO Feng WANG Lin CHEN Pengfei LI xiaoke {1. The School of earth Science and Resources Chang’an UniversityXi’an 710054China State Key Laboratory of Loess and Quaternary Geology Institute of Earth and EnvironmentCASXi’an 710061China College of Urban and environmental Science Northwest UniversityXi’an 710069China CAS Center for Excellence in Quaternary Science and Global Change Xi’an 710061China

Reflectance spectroscopy is rapid,inexpensive,and non-destructive and can provide important information about the mineralogy of rocks and *** measured the reflectance spectroscopy of Miocene red clay deposits on the northeastern margin of the Tibetan Plateau,with the aim of developing a rapid methodology for detecting paleoclimatic *** obtained visible/near-infrared(VNIR)and short-wave infrared(SWIR)spectroscopy data from the red clay in the Jianzha Basin,and analyzed their relationship with independent paleoclimatic records,including mineral contents and environmental magnetic *** results show that the VNIR parameters,including D500,D900,R500,and R900(where D and R represent the depth and reflectance of the absorption peaks around 500 and 900 nm,respectively)are temperature-sensitive and correlated with the magnetic susceptibility,frequency-dependent magnetic susceptibility,and the marine δ^(1.)O *** results of frequency-domain analysis of the VNIR parameters show that they reflect climate change on orbital *** parameters,such as AS1.00,D1.00/D1.00 and D1.00(where AS represents the asymmetry of the absorption peaks around1.00 nm),are correlated with the illite and montmorillonite content,and they are sensitive to the weathering *** spectral parameters of the eolian red clay in the Jianzha Basin reflect regional climatic changes caused by the uplift of the Tibetan Plateau at~8.5 Ma and global climatic cooling at~7.2.Ma,and thus they are applicable as both regional and global paleoenvironmental indicators.

关键词： Visible/near-infrared spectroscopy Short-wave infrared spectroscopy Paleoclimatic indicators Red clay Tibetan Plateau

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The microtine distribution and its environmental significance since the Middle Pleistocene in Zhangping Caves of the Qinling Mountains

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Science china {1. {2. 2008年第2期51卷 294-299页

作者： LI Yongxiang1.& XUE xiangXu1.2.1.State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, institute of Cenozoic Geology and {1., xi’an 71.069,{2. 2.7}, State Key Laboratory of Loess and Quaternary Geology, chinese academy of sciences, xi’an 710075,{2. 1. State Key Laboratory of Continental Dynamics Department of Geology Northwest University Institute of Cenozoic Geology and Environment Xi’an 710069 China 2. institute of earth environment State Key Laboratory of Loess and Quaternary Geology Chinese Academy of Sciences Xi’an 710075 China

Three microtine species are recovered from the Zhangping Caves of the Qingling Mountains, namely Microtus oeconomus, Caryomys inez and Caryomys eva. They are climate-sensitive ones with different ecological habits, therefore their distribution well corresponds to environmental variations. Statistical comparison of the distribution of fossil microtines and their counterparts nowadays displays that the climate variation of the studied area and its contiguity since the middle Pleistocene are: warm and humid at 493.ka ago, cool and humid at 2.9 ka ago―cold and humid at 2.5 ka ago―cool and humid at 2. ka ago, and warm and dry at present.

关键词： environmental variation since Middle Pleistocene microtine fossils Zhangping Caves of the Qinling Mountains

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Ecological response to the climate change on the northern slope of the Tianshan Mountains in xinjiang

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Science china {1. {2. 2005年第6期48卷 765-777页

作者： CHEN xi1. LUO Geping1. xiA Jun2. ZHOU Kefa1. LOU Shaoping3.& YE Minquan4 1. xinjiang institute of Ecology and Geography,{1., Urumqi 83.01.,{2. 2. institute of Geographical and Resources sciences,{1., Beijing 1.01.1.{2. 3. Urumqi Meteorological-satellite Land Station, Urumqi 83.01.,{2. 4. Seismological Bureau of xinjiang Uygur Autonomous Region, Urümqi 83.01.,{2. Correspondence should be addressed to Chen xi 1. xinjiang institute of Ecology and Geography Chinese Academy of Sciences 830011 Urumqi China 2. institute of Geographical and Resources {1. Chinese Academy of Sciences 100101 Beijing China 3. Urumqi Meteorological-satellite Land Station 830011 Urumqi China 4. Seismological Bureau of xinjiang Uygur Autonomous Region 830011 Urümqi China

The Tianshan Mountains is a high and huge mountain body lying across the central part of xinjiang, china, and is also the main area where the runoff forms in xinjiang. In this paper, a set of RS-based study methods is put forward for deriving the information about the natural change of the ecology in arid areas, and the relationship between the climate change trend and the corresponding ecological response on the northern slope of the Tianshan Mountains since recent 40 years is analyzed from the scales of the land cover ecosystems and landscapes based on the observed data of climate, hydrology, modern glaciers and lakes on the northern slopes of the Tianshan Mountains since recent 40 years and the satellite RS data since recent 1. years by using the RS and GIS technologies. The results are as follows: (1. The overall trend of climate change on the northern slope of the Tianshan Mountains since recent 40 years is that both air temperature and precipitation are increased, especially the increase amplitudes of air tempera-ture, precipitation and annual runoff volume are high since the decade of the 1.90s; (2. the in-tegrated indexes of the vegetation in all the geographical divisions on the northern slope of the Tianshan Mountains are obviously increased since recent 1. years, especially in the artificial oases and the foothill belts, such a change trend is advantageous for improving the vegetation ecology; and (3. the vegetation ecology in the arid areas is extremely sensitive to the climate change, the vegetation coverage and the biomass on the northern slope of the Tianshan Moun-tains are continuously increased because of the climate change since recent 1. years, their in-crease amplitudes in the plains and during the late stage are obviously higher than that in the mountainous regions and during the early stage.

关键词： north slope of the Tianshan Mountains, climate change, hydrological change, natural change of ecology,RS and GIS, vegetation index.

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Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

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Science china {1. {2. 2008年第5期51卷 654-664页

作者： HU Guang1.2. JIN ZhangDong1.& ZHANG Fei3.1.State Key Laboratory of Loess and Quaternary Geology, institute of earth environment,{1.,{2.,{3. 2.Graduate University of the{1., Beijing 1.0049,{3. 3.College of Resources and environmental Science, Nanjing Agricultural University, Nanjing 2.0}095,{3. State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China Graduate University of the chinese academy of sciences Beijing 100049 China College of Resources and Env

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (1.–55 m) of the Hequing Basin in Yunnan Province, southwest china. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1. the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; ({3. the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3. the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

关键词： ostracod shell molar Sr/Ca ratio molar Mg/Ca ratio environmental response Heqing Basin

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Neogene eolian deposits within the West Qinling Mountains:Climatic and tectonic implications

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chinese Science Bulletin 2010年第15期55卷 1483-1487页

作者： GE JunYi 1.2.& GUO ZhengTang 3.1.State Key Laboratory of Loess and Quaternary Geology (SKLLQG),{2. of {1. {2.,{3. academy of sciences,xi’an 710075,china 2.Graduate University of chinese academy of sciences,Beijing 1.0049,china 3.Key Laboratory of Cenozoic Geology and {2.,{2. of Geology and Geophysics,{3. academy of sciences,Beijing 1.002.,china State Key Laboratory of Loess and Quaternary Geology (SKLLQG) Institute of Earth Environment Chinese Academy of Sciences Xi''an 710075 China Graduate University of chinese academy of sciences Beijing 100049 China Key Laboratory of Cenozoic Geology and environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

The Qinling Mountains constitute a key climate barrier between southern and northern *** recent investigations revealed widely spread eolian deposits of Neogene age mantling the piedmont highlands of the intermountain basins within West ***-mammalian fossils dated a 1.0.2.m section (NL-VI) near xihe for the late Miocene to Pliocene (～1.-4 Ma).Soil micromorphology,grain-size and geochemical analysis consistently define typical loess-soil alternations for the upper (0-66 m) and lower (98-1.0.2.m) parts of the section,with the middle section (66-98 m) having been affected by episodic slope *** results add important insights to the earlier studies about the widespread eolian deposition in northern china during the Miocene,prior to 8 *** also suggest that the basic configuration of the ridges and inter-ridge basins of West Qinling has already formed by ～1. *** well-preserved eolian deposits are unlikely to support intense substratum deformation and rapid uplift of West Qinling since the late Miocene.

关键词：秦岭山脉风尘堆积构造意义气候新近纪晚中新世地球化学分析风尘沉积

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Origin of the Red earth sequence on the northeastern Tibetan Plateau and its implications for regional aridity since the middle Miocene

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Science china {1. {2. 2006年第5期49卷 505-517页

作者： WANG xianyan1,7, LU Huayu1,2. JI Junfeg3. WANG xiaoyong1,7, ZHAO Jingbo4, HUANG Baochun5 & LI Zhen6 1. SKLLQG, institute of earth environment,{1.,{2.,{3. 2. Department of Urban and Resources sciences, Nanjing University, Nanjing 2.0093.{3. 3. Department of earth sciences, Nanjing University, Nanjing 2.0093.{3. 4. Department of Geography, Shaanxi Normal University, xi’an 710062.{3. 5. {1.} of Geology and Geophysics,{1., Beijing 10002.,{3. 6 Department of Geography, Qinghai Normal University, xining 810008,{3. 7. Graduate School of the{1., Beijing 10003.,{3. 1. SKLLQG Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China 7. Graduate School of the chinese academy of sciences Beijing 100039 China 2. Department of Urban and Resources sciences Nanjing University Nanjing 210093 China 3. Department of earth {1. Nanjing University Nanjing 210093 China 4. Department of Geography Shaanxi Normal University Xi’an 710062 China 5. institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China 6. Department of Geography Qinghai Normal University Xining 810008 China

The Red earth deposit around xining, northeastern Tibetan Plateau, has beenstudied in terms of soil micro-structure, grain-size distribution, major- and trace-elementchemistry and magne-tostratigraphy. Field investigations indicate that the Red earth sequenceconsists of 2. visually definable yellow-brown and weakly-developed soils interbedded with reddishstrongly-developed soils, and has a similar structure to the aeolian Red Clay deposit on the {2.Loess Plateau. Grain-size analysis shows that the Red earth deposit is very fine-grained with anegligible sand fraction ( > 63.μm). Thin-section observations under light microscopy show that thedeposit has a clayey texture and the coarse fraction ( > 1. μm) mainly consists of quartz,feldspar and micas. Pyroxene and hornblende were also observed. This mineralogical composition ofthe coarse fraction is similar to that of the Quaternary loess. In addition, all of the mineralgrains are semi angular semi-angular and are generally finer than 63.μm. There is a good agreementbetween the major and minor trace element chemistry of loess-soil units and the Red earth *** REE distributions of the loess-soil and the Red earth deposit are similar in shape, withenriched LREE and fairly flat HREE profiles and a clear negative Eu anomaly. The geochemicalcharacteristics of the Red earth deposit are also identical to those of upper continental crust,thus indicating a wind-blown origin. Magnetostratigraphic investigation shows that onset of the Redearth deposition predates 1..4 Ma BP (1..6 Ma at a nearby site). The distribution of the reportedMiocene aeolian loess at Qin''an of the Loess Plateau is still unknown. Our results indicate thatthis aeolian deposit had extended to the northeastern Tibetan Plateau by at least the middleMiocene. The similarity of the element geochemistry between the Red earth deposit and the overlyingloess shows that they may have similar sources and dynamic transport system, and may indicate thatthe

关键词： Red earth deposit, Northeastern Tibetan Plateau, aeolian deposit, aridity of Asia, the middle Miocene.

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Nitrogen isotopic composition of plant-soil in the Loess Plateau and its responding to environmental change

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chinese Science Bulletin 2009年第2期54卷 272-279页

作者： LIU WeiGuo1.2.& WANG Zheng1.3.1.State Key Laboratory of Loess and Quaternary Geology, institute of earth environment,{1.,{2.,{3. 2.xi’an Jiaotong University, School of Human Settlement and Civil Engineering, xi’an 71.049,{3. 3.Graduate University of{1., Beijing 1.0049,{3. chinese Acad Sci Inst Earth Environm State Key Lab Loess and Quaternary Geol Xian 710075 Peoples R China.

The nitrogen isotope of soil is of emerging significance as an indicator of climatic change and biogeochemical cycle of nitrogen in nature systems. In this paper, the nitrogen content and isotopic composition of modern ecosystems from arid and semiarid Loess Plateau in northwestern china, including plant roots and surface soil, were determined to investigate trends in δ1.N variation of plant roots and soil along a precipitation and temperature gradient in northwestern china under the East Asian Monsoon climate condition. The δ1.N values of surface soil from the study area vary from ?1.2. to 5.8‰, but from -5.1. to 1.9‰ in the plant roots. Our results indicate that (1. although the isotopic compositions of both plant roots and surface soil change with a similar trend along the climate gradient, the apparent nitrogen difference between plant roots and soil existed, with -δ1.N values ranging from 0.3. to 7.2. with average of 4.1.; and (2. mean annual precipitation (MAP) is the dominant factor for isotopic composition of plant-soil nitrogen in the Loess Plateau, and the δ1.N values are less correlated with MAT; we suggest that nitrogen isotopic composition of soil is a potential tracer for {2.al changes.

关键词：氮同位素物理性质化学性质环境论

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