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Simulating the transfer and fate of hexachlorocyclohexane in recent 50 years in beijing, China

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Science China earth sciences 2005年第12期48卷 2203-2213页

作者： CAO Hongying1, LIANG Tao1 & TAO Shu2 1. Institute of Geographical sciences and Natural Resources Research, Chinese Academy of sciences, beijing 100101, China 2. {3. for{4. surface processes, peking university, beijing 100871, China Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing China laboratory for earth surface {3. Peking University Beijing China

Taking beijing as a study area, a dynamic fugacity model was used to simulate the transfer and fate of technical HCHs according to the physic-chemical properties of the studying environment and HCH isomers. Dynamic changes of the transfer fluxes and concentrations of HCH isomers during 1952―2003.were simulated and the model results suggest good agreement between the calculated and measured concentrations of HCH isomers. During 1952―1983. the average input and output amount of HCHs through agricultural application and degradation are 13. t and 150 t respectively. The dominant transfer {4. of HCHs in the study area are air-soil deposition, soil erosion and soil-air diffusion, transfer fluxes of these {4. are 80 t?a?1, 16 t?a?1 and 11 t?a?1, which account for 92% of total transfer fluxes of HCHs isomers. There were approximately 253. HCHs in all {3. compartments of the study area during this period and 97% of which existed in soil compartment. Air and water advection became the dominant input sources of HCHs after 1984.when the application of technical HCHs was prohib-ited, concentration of HCHs quickly descended to a quite low level in several years. Total amount of HCHs isomers remaining in the study area environment now is less than 5% that before 1983. and this percentage may descend to 0.5% after 20 years by prediction.

关键词： fugacity model, hexachlorocyclohexane, compartment, transfer flux, fate.

Size-dependent hydroxyl radicals generation induced by SiO_2 ultra-fine particles: The role of surface iron

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Science China Chemistry 2009年第7期52卷 1033-1041页

作者： SHANG Yu1, ZHU Tong1, LI Yi1,2 & ZHAO JinCai3.1 college of environmental sciences and Engineering,{3., beijing 100871, China 2 Chinese Academy of Meteorological sciences, beijing 100871, China 3.Institute of Chemistry, Chinese Academy of sciences, beijing 100871, China college of environmental sciences and Engineering Peking University Beijing China Chinese Academy of Meteorological sciences Beijing China Institute of Chemistry Chinese Academy of Sciences Beijing China

Oxidative stress and hydroxyl radicals (·OH) play important roles in adverse health effects caused by inhalable ambient air particles (PM10). The ultra-fine fraction of PM10 has been hypothesized as one of the critical contributors to ·OH generation. Both in vivo and in vitro studies have shown that ultra-fine particles (UFPs) or nano-particles generate more ·OH than larger particles with identical mass and composition. Both the surface area and surface-adsorbed redox-active metals have been suggested as factors to determine the oxidative capacity of UFPs. In this study, the ·OH-generating capability of dif-ferent sizes of SiO2 particles was investigated in order to determine which factor influences particle-induced ·OH generation. The amount of ·OH generated in both acellular and cellular systems was quantified using a capillary electrophoresis method following exposure to SiO2 particles with diameters of 14. 100, and 500 nm. The amount of ·OH was strongly dependent on particle size, and a significant enhancement was observed only with 14.nm particles. Further studies indicated a close association between ·OH and iron ion concentration (R2 = 0.812, psurface iron being removed, did not generate ·OH. The iron-containing leachate from these washings was able to enhance ·OH production as untreated particles did. Therefore, the presence of adsorbed iron on the surface of the SiO2 particles is presented as a possible mechanism of UPFs-induced ·OH generation. The SiO2 acted as an inert substrate, and the surface of ultra-fine SiO2 particles acted as a carrier for iron.

关键词： ultra-fine particles nano-particles ·OH oxidative stress size-effect

Redevelopment of liftoff rates of saltating sand grains based on a simple optimization model

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Science China earth sciences 2010年第4期53卷 568-574页

作者： CHENG Hong & ZOU XueYong State Key laboratory of earth surface {3. and Resource Ecology,{4. Normal university,{4. 100875,China moe Engineering Center of Desertification and Blown-sand Control,{4. Normal university,{4. 100875,China Key laboratory of environmental Change and Natural Disaster of the Ministry of Education of China,{4. Normal university,{4. 100875,China State Key laboratory of earth surface {3. and Resource Ecology Beijing Normal University Beijing China moe Engineering Center of Desertification and Blown-sand Control Beijing Normal University Beijing China Key laboratory of environmental Change and Natural Disaster of the Ministry of Education of China Beijing Normal University Beijing China

This paper is a redevelopment result of liftoff rates of saltating sand grains based on our previous *** sand flow is a complex multi-phase flow because of a special two-phase gas-solid flow near ground *** extensive research on the movement of blowing sand,no model fully characterizes aeolian sand flow,and large differences often exist between simulations of aeolian sand movement and field *** key problem is a few of sufficient research on liftoff rates of saltating sand grains(also called the number of liftoff sand grains per unit time and per unit bed area).It is necessary to re-search in advance liftoff rates of saltating sand *** redeveloped liftoff rates of saltating sand grains by establishing an optimization model based on the flux of aeolian sand flow at different heights of the sampler in wind tunnel and the simulated capture of saltating sand grains by different heights of the sampler that are from different liftoff position(distance from the sampler) in order to revise previous inversion condition of liftoff rates of saltating sand *** rates increased rapidly with increasing wind *** frictional wind velocities of u=0.67,0.77,0.82,0.83.and 0.87 m s-1,liftoff rates were 3.4.,954.02,523.114.54.94.7,and 7696291 sand grain s-1 m-2,*** rates could be expressed as the square of the instantaneous frictional wind velocity and a constant(0.663. that differs from the critical(threshold) frictional wind velocity at which saltation *** our results require additional experimental validation and the simple optimization model must be improved,they nonetheless provide a strong basis for future research.

关键词： liftoff rates of saltating sand grains optimization model wind tunnel two-phase gas-solid flow

Contribution of Root and Microbial Respiration to Soil CO_2 Efflux and Their environmental Controls in a Humid Temperate Grassland of Japan

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Pedosphere 2009年第1期19卷 31-39页

作者： WANG Wei FENG Jiang T. OIKAWA Department of Ecology College of Urban and Environmental Sciences and Key Laboratory for Earth Surface Processes of the Ministry of Education Peking University Beijing 100871 （China） School of Urban and environmental sciences Northeast Normal University Changchun 130024 （China） Institute of Biological sciences University of Tsukuba Tsukuba Ibaraki 305-8572 （Japan）

Soil CO2 efflux, root mass, and root production were investigated in a humid temperate grassland of Japan over a growing season （Apr. to Sep.） of 2005 to reveal seasonal changes of soil CO2 efflux, to separate the respective contributions of root and microbial respiration to the total soil CO2 efttux, and to determine the environmental factors that control soil respiration. Minimal microbial respiration rate was estimated based on the linear regression equations between soil CO2 effiux and root mass at different experimental sites. Soil CO2 efflux, ranging from 4.99 to 16.29 μmol CO2 m^-2 s^-1, depended on the seasonal changes in soil temperature. The root mass at 0-10 cm soil depth was 0.82 and 1.27 kg m^-2 in Apr. and Sep., respectively. The root mass at 0-10 cm soil depth comprised 60% of the total root mass at 0-50 cm soil depth. The root productivity at 0-3. cm depth varied from 8 to 180 g m^-2 month^-1. Microbial and root respiration rates ranged from 1.3. to 5.51 and 2.72 to 12.06μmol CO2 m^-2 s^-1, respectively. The contribution of root respiration to the total soil CO2 efflux averaged 53., ranging from 3.% to 72%. The microbial respiration rate was exponentially related to soil temperature at 10 cm depth （R^2 = 0.94.0, P = 0.002, n = 6）, and the root respiration rate was linearly related to the root production at 0-3. cm depth （R2 = 0.6561, P = 0.04., n = 6）.

关键词： grasslands microbial respiration root production root respiration

Heterogeneous reactions of SO_2 on ZnO particle surfaces

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Science China Chemistry 2011年第1期54卷 161-166页

作者： LI Jia,SHANG Jing & ZHU Tong State Key Joint laboratory of environmental Simulation and Pollution Control college of environmental{4. and Engineering,peking university,beijing 100871,China State Key Joint laboratory of environmental Simulation and Pollution Control college of environmental sciences and Engineering Peking University Beijing China

Heterogeneous reactions of SO2 on ZnO particle surfaces were studied using in situ diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）. The influences of relative humidity （RH） and UV radiation （2= 3.5 nm） were investigated. In the absence of UV radiation, sulfite was the prominent product on the particle surfaces, and a negative relationship between RH and sulfite production was observed. In the presence of UV radiation, infrared （IR） absorption of sulfite and sulfate was evident in the spectra. With increasing RH or UV intensity, sulfite was gradually transformed into sulfate. UV intensity and RH exhibited a synergistic effect on the heterogeneous oxidation of SO2 on ZnO. On dry particles and with no UV radiation, the reaction order of SO2 on ZnO particles was 1.6. The initial uptake coefficient for the formation of sulfite, using the Brunauer-Emmett-Teller （BET） area as the reactive surface area of SO2, was 4.87 × 10^-6. At 4.% RH and with UV radiation, the reaction order was 0.91, and the initial uptake coefficient was 2.29 ×10^-5.

关键词： SO2 ZnO DRIFTS heterogeneous oxidation UV radiation

The roles of heterogeneous chemical processes in the formation of an air pollution complex and gray haze

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Science China Chemistry 2011年第1期54卷 145-153页

作者： ZHU Tong,SHANG Jing & ZHAO DeFeng State Key Joint laboratory of environmental Simulation and Pollution Control college of environmental{4. and Engineering,peking university,beijing 100871,China State Key Joint laboratory of environmental Simulation and Pollution Control college of environmental sciences and Engineering Peking University Beijing China

Urban and regional air pollutions are characterized by high concentrations of secondary pollutants such as photo-oxidants （mainly ozone） and fine particulate matter, which are formed through chemical reactions of the primary pollutants emitted from various sources. The accumulation of these pollutants under stagnant meteorological conditions results in the formation of gray haze, reducing visibility and causing major impacts on human health and climate. In an air pollution complex, the co- existence of high concentrations of primary and secondary gaseous and particulate pollutants provides a large amount of reac- tants for heterogeneous reactions on the surface of fine particles; these reactions change the oxidizing capacity of the atmos- phere, as well as chemical compositions along with the physicochemical and optical properties of particulate matter, thereby accelerating formation of the air pollution complex and gray haze. Using in situ technologies, such as diffuse reflectance infra- red Fourier-transform spectroscopy and single-particle Raman spectroscopy, we systematically investigated the reaction kinet- ics and mechanisms of gaseous pollutants （i.e., NO2, SO2, 03. and formaldehyde） on the surfaces of the major components of atmospheric particles such as CaCO3. kaolinite, montmorillonite, NaC1, sea salt, A1203. and Tit2. We found that the main re- action products were sulfate, nitrate, or formate, which can change the hygroscopicity and light extinction parameters of those particles significantly. By analyzing the reaction kinetics of these heterogeneous reactions, we identified synergetic mechanisms of the three ternary reaction systems, ,i.e., NOE-particles-H2O, SO2-particles-O3. and organics/SO2-particles-UV illumination. These synergetic mechanisms can provide experimental and theoretical bases for understanding the feedback mechanisms and nonlinear processes in the formation of an air pollution complex and gray haze.

关键词： fine particles secondary pollutants oxidizing capacity ternary reaction nonlinear processes

Variations in carbon isotope ratios of C_3.plants and distribution of C_4.plants along an altitudinal transect on the eastern slope of Mount Gongga

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Science China earth sciences 2009年第10期52卷 1714-1723页

作者： LI JiaZhu1, WANG GuoAn2, LIU XianZhao1, HAN JiaMao3. LIU Min4.& LIU XiaoJuan2 1 college of Geography and Planning, Ludong university, Yantai 264.25, China 2 Key laboratory of Plant-Soil Interactions, Ministry of Education, college of Resources and {4. sciences, China Agri- cultural university, beijing 100193. China 3.Institute of Geology and Geophysics, Chinese Academy of sciences, beijing 100029, China 4.college of {4. sciences,{13., peking university, beijing 100871, China college of Geography and Planning Ludong University Yantai China Key laboratory of Plant-Soil Interactions Ministry of Education College of Resources and Environmental Sciences China Agricultural University Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China college of environmental sciences MOE Laboratory for Earth Surface Processes Peking University Beijing China

Variations in carbon isotopic ratios (δ 13.) of C3.plants and distribution of C4.plants were investigated along an altitudinal transect on the eastern slope of Mount Gongga, and the environmental effects on them were discussed. It is shown that plants with C4.photosynthetic pathway mainly occur at altitudes below 2100 m a.s.l., suggesting that the low summer temperature is responsible for the distributional pattern. In addition, δ 13. of C3.plants increases with elevation at the region above 2000 m a.s.l. with the characteristics of humid climate, and the increase rate in δ 13. for C3.plants is about 1.3. per kilometer. Temperature determines the altitudinal trend of δ 13..

关键词： Mount Gongga carbon isotopic ratios C3.C4 plants C4 distribution altitude

Heterogeneous reactions on the surface of fine particles in the atmosphere

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Chinese Science Bulletin 2003年第21期48卷 2267-2276页

作者： DING Jie & ZHU Tong State Key Joint laboratory of environmental Simulation and Pollution Control, college of environmental{4., peking university, beijing 100871, China Correspondence should be addressed to Zhu Tong (e-mail:tzhu@ ***) State Key Joint laboratory of environmental Simulation and Pollution Control College of Environmental Sciences Peking University Beijing China

Fine particles play an important role in the atmosphere. Research on heterogeneous reactions on the surface of fine particles is one of the frontier areas of atmospheric science. In this paper, physical and chemical characteristics of fine particles in the atmosphere and the interactions between trace gases and fine particles are described, methods used in heterogeneous reactions research are discussed in detail, progress in the study of heterogeneous reactions on the surface of fine particles in the atmosphere is summarized, existing important questions are pointed out and future research directions are suggested.

关键词：细微颗粒大气科学多相反应空气动力学

“Tali Glaciation” on Massif Diancang

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Science China earth sciences 2007年第11期50卷 1685-1692页

作者： YANG JianQiang1, CUI ZhiJiu2, YI ChaoLu1, SUN JiMin3.& YANG LiRong3.1 Institute of Tibetan Plateau Research, Chinese Academy of sciences, beijing 100085, China 2 {4. of {3. sciences, peking university, beijing 100871, China 3.Institute of Geology and Geophysics, Chinese Academy of sciences, beijing 100029, China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China college of environmental sciences Peking University Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China

The term of ''Tali Glaciation'' is nominated from Massif Diancang in Yunnan Province. The confusing process of the term''s being put forward is confirmed through literature checking. Based on several times of field trip, the glacial landforms in this region are studied in detail, and the magnitude of the glaciation was determined. According to the numerical ages from TL, AIMS ^(14.C and OSL dating, the earliest glacial advance on Massif Diancang occurred at 3.—4. ka BP, followed by the advances at the last stage of the last glaciation, the late glacial and neoglations in turn, until glaciers vanished at 1.2—1.5 ca. a BP in this region. It can be concluded that glaciers were limited above 3.00 m a.s.l., and no glaciers existed on the lower part and adjacent mountains since the last glaciation.

关键词： Massif Diancang,Tali Glaciation,glacial landform,glaciation sequence,numerical dating