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Boron isotopic fractionation in laboratory inorganic carbonate precipitation:Evidence for the incorpora-tion of B(OH)_3 into carbonate

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Science china Earth sciences 2008年第12期51卷 1776-1785页

作者： XIAO YingKai1,2, LI HuaLing1,3, liu WeiGuo4, wang XiuFang1 & JIANG ShaoYong5 1 Qinghai institute of Salt Lakes, chinese academy of sciences, Xining 810008, china 2 state key laboratory of environmental geochemistry, institute of geochemistry, chinese academy of sciences, guiyang 550002. china 3 Nanjing institute of Geology and Mineral Resources, Nanjing 210016, china 4 state key laboratory of Loess and Quaternary Geology, institute of Earth Environment, chinese academy of sciences, Xi’an 710075, china 5 state key laboratory for Mineral Deposits Research, Department of Earth sciences, Nanjing University, Nanjing 210093, china Qinghai institute of Salt Lakes Chinese Academy of Sciences Xining China state key laboratory of environmental geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang China Nanjing institute of Geology and Mineral Resources Nanjing China state key laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an China state key laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing China

A laboratory inorganic carbonate precipitation experiment at high pH of 8.96 to 9.34 was conducted, and the boron isotopic fractionations of the precipitated carbonate were measured. The data show that boron isotopic fractionation factors (αcarb-3) between carbonate and B(OH)3 in seawater range 0.937 and 0.965, with an average value of 0.953. Our results together with those reported by Sanyal and collabo-rators show that the αcarb-3 values between carbonate and B(OH)3 in solution are not constant but are negatively correlated with the pH of seawater. The measured boron isotopic compositions of carbonate precipitation (δ11Bcarb) do not exactly lie on the best-fit theoretical δ 11B4-pH curves and neither do they exactly parallel any theoretical δ 11B4-pH curves. Therefore, it is reasonable to argue that a changeable proportion of B(OH)3 with pH of seawater should also be incorporated into carbonate except for the dominant incorporation of B(OH)4- in carbonate . Hence, in the reconstruction of the paleo-pH of sea-water from boron isotopes in marine biogenic carbonates, the use of theoretical boron isotopic frac-tionation factor (α4-3) between B(OH)4- and B(OH)3 is not suitable. Instead, an empirical equation should be established.

关键词： boron isotopic fractionation biogenic carbonate B(OH)3 incorporation

Regulation mechanism of EM parameters in natural ferrite and its application in microwave absorbing materials

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Science china(Technological sciences) 2006年第1期49卷 38-49页

作者： ZHENG Yongchun1,2, wang Shijie2, FENG Junming2, LI Chunlai1, OUYANG Ziyuan1,2, liu Jianzhong1 & LI Xiaobiao2 1. National Astronomical Observatories, chinese academy of sciences, Beijing 100012, china 2. state key laboratory of environmental geochemistry, institute of geochemistry, chinese academy of sciences, guiyang 550002. china National Astronomical Observatories Chinese Academy of Sciences Beijing China state key laboratory of environmental geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang China

Electromagnetic (EM) parameters (ε ′, ε ″, μ ′, μ″ ) of several M2+Fe2O4 and Fe2O3 type natural ferrites with different geological occurrences are measured in this pa-per. The measurement results show that EM parameters of a magmatic-occurring natural ferrite is very different from other types occurring from sedimentary-metamorphic iron deposit, hydrothermal vein iron deposit, outer contact of magmatic iron deposit. It has potential to be used as magnetic absorbent in microwave absorbing materials. After min-eral separation and concentration, this magmatic-occurring natural ferrite was processed into type A ferrite absorbent. Type A natural ferrite absorbent is a kind of magnetic material with low dielectric constants, high magnetic conductivity and high EM loss. Its EM pa-rameters are ε ′ = 58.60, ε ″ = 10.0, μ ′ = 1.2-1.5, μ ″ = 1.0-1.2, respectively. In order to illuminate the regulation mechanism of EM parameters, we studied the chemical and mineral composition of type A ferrite absorbent. There is high concentration of natural impurities, which regulate the EM parameters of type A ferrite greatly. For comparison, the other types of natural ferrite, single-phase magnetite and two-phase iron minerals (ilmen-ite and magnetite), have few impurity. Thus regulation mechanism of EM parameters was absent in these ferrites. As a result, the regulation of EM parameters is advantageous to develop type A natural ferrite as excellent absorbent, lowers the reflectivity coefficients and enhances the absorbing efficiency of MAM made from it. Furthermore, the impurities in type A natural ferrite and its effects on EM parameters are very difficult to simulate in the synthesize ferrite. The carbonyl-iron powder is another kind of absorbent that is used ex-tensively in MAM. To compare the absorbing properties of these two absorbent, type A natural ferrite and carbonyl-iron powder were mixed with rubber and processed into mi-crowave absorbing sheets with the same procedures and tec

关键词： natural impure ferrite, complex permittivity, complex permeability, microwave absorbing materials.

PCBs and OCPs in sediments from Hongfeng Reservoir in Guizhou Province,china

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Acta Geochimica 2006年第S1期 69-70页

作者： Zhongqing WEI1,2, congqiang liu1, Xiaobing LIANG1, Fushun wang1, Shaofeng wang1,2 1 state key laboratory of environmental geochemistry, institute of geochemistry, chinese academy of sciences, guiyang 550002. china 2 Graduate School of chinese academy of sciences, Beijing 100049, china

Early diagenesis of nurtrients (C, N, P and Si) stored in sediments of two reservoirs in southwestern china

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Acta Geochimica 2006年第S1期 161-162页

作者： Yuchun wang1, Jun ZHU2, congqiang liu2 1 Dept. of Water Environment, china institute of Water Resources and Hydropower Research, Beijing 100044, china 2 state key laboratory of environmental geochemistry, institute of geochemistry, chinese academy of sciences, guiyang 550002. china

Degradation of organic matterin the sediments of Hongfeng Reservoir

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Science Bulletin 2005年第20期 123-126页

作者： WEI Zhongqing1,2, liu congqiang1, LIANG Xiaobing1, wang Fushun1 & wang Shaofeng1, 2 1. state key laboratory of environmental geochemistry, institute of geochemistry, chinese academy of sciences, guiyang 550002. china 2. Graduate School of the chinese academy of sciences, Beijing 100039, china

In this work, the distribution of organic carbon, DNA and lipids in the sediments of Hongfeng Reservoir were described in addition to SO42? profile in pore water. The con- tents of organic carbon in the sediments range from 23.3 to 76.8 mg·g?1, with the peak value appearing at the depth of 8 cm bellow the sediments water interface (SWI), and tend to decrease gradually with sedimentation depth. The concentra- tions of SO42? decreased from 40.50 mg·L?1 to 12.00 mg·L?1 at SWI in top 4 cm sediment, and was kept at 12.0 mg·L?1 bel- low that depth. Newly produced organic carbon can be con- served as long as 14 years in the sediments. The contents of DNA were relatively high in top 9 cm surface sediments, as revealed by agarose gel images, close to those of organic car- bon and sulphate reduction index (SRI). This study shows that bacteria played an important role in organic matter degradation; SO42? is the primary electron acceptor under anaerobic condition in this reservoir; DNA in the lake sedi- ments can provide important information for the study of cycling of nutrient elements in the lake.

关键词： lake sediment DNA organic carbon electrophoresis sulfate.

Micro area transportation of residues: A style forming the red weathering crusts of carbonate rocks

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Acta Geochimica 2006年第S1期 170-171页

作者： Zhigang FENG1, Shijie wang2, Xiuming liu2, Weijun LUO2, Qingliang wang1 1 College of Construction Engineering & Resource Environment, Nanhua University, Hengyang 421001, china 2 The state key laboratory of environmental geochemistry, institute of geochemistry, chinese academy of sciences, guiyang 550002. china

Distributions of dissolved rare earth elements during estuarine mixing at the Changjiang River mouth

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chinese Science Bulletin 2000年第19期45卷 1795-1799页

作者： zhongliang wang congqiang liu chinese Acad Sci Inst Geochem State Key Lab Environm Geochem Guiyang 550002 Peoples R China

The first data on the concentrations of dissolved REE in surface waters collected from the north passage of the Changjiang Estuary where the salinity ranges from 0.15 to 19 mg/g were determined by ICP-MS after preconcentration with solvent extraction and back-extraction techniques. Relative to other estuaries, the river-water end-member concentrations of dissolved REE are very low, ranging from 11.963 (Y) to 0.098 ng/kg (Lu). Dissolved REE removed markedly from water in the Changjiang Estuary where salinity lies within the range of 0.15-1 mg/g, but the percent removal is low, ranging only from 47%(La) to 25%(Lu). Strong water-sediment interaction due to shallow water depth in the Changjiang Estuary leads to remarkable concentration peaks of dissolved REE in the location where the salinity varies from 1 to 8 mg/g. In the moderate and high salinity regions from 8 to 19 mg/g, the concentrations of dissolved REE gradually increase as a result of desorption or partial dissolution of particles.

关键词： Changjiang Estuary rare earth elements distributions removal desorption.

Aqueous geochemistry of rare-earth elements in karst lakes, southwestern china

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Acta Geochimica 2006年第S1期 171-171页

作者： zhongliang wang, congqiang liu, Zhaozhou ZHU state key laboratory of environmental geochemistry, institute of geochemistry, chinese academy of sciences, guiyang 550002. china

Effect of transition metals on the growth and activity of external carbonic anhydrase of two green algae

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Acta Geochimica 2006年第S1期 145-145页

作者： Baoli wang, congqiang liu state key laboratory of environmental geochemistry, institute of geochemistry, chinese academy of sciences, guiyang 550002. china