检索结果-南通市图书馆

Estimation of tree transpiration and response of tree conductance to meteorological variables in desert-oasis system of Northwest China

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2004年第Z1期47卷 9-20页

作者： CHEN Rensheng KANG Ersi ZHANG Zhihui ZHAO Wenzhi SONG Kechao ZHANG Jishi LAN Yongchao Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

Transpirations of three dominated tree species, namely Mongol Scotch Pine (Pinus sylvestris var. mongolica Litvin), White elm (Ulmus pumila) and Gansu Poplar (Populus gansuensis Wang et Yang) in oasis shelter forest (Linze site) and of two dominated tree species,namely Euphrates Poplar (Populus euphratica Oliv.) and Russia olive (Elaeagnus angustifolia Linn.) in lowland desert (Erjinaqi site) have been estimated using measured sapflow in summer,autumn and winter, 2002 and in spring, 2003. An ENVIS System was used for each site to measure microclimate variables, soil moisture and sapflow every half an hour, and the study time scale is one day. In the 104 days of observation during the growing season at the Linze site, the average daily sapflow of Gansu Poplar is 9.93L·d-1,and the average transpiration per unit leaf area is 1.99mm·*** White elm tree,the daily average sapflow is 4.08L·d-1,while the daily average transpiration per unit leaf area is 0.49mm·*** values for Mongol Scotch Pine are 3.91L·d-1 and 0.25mm·d-1,*** the total 73 days of observation during the growing season at the Erjinaqi site, the daily average sapflows of Russia olive and Euphrates Poplar are 12.1 and 20.97L·d-1,respectively,and the average transpirations per unit leaf area are 0.22 amd 0.31mm·d-1,*** the observation period of the growing season,tree conductances of Mongol Scotch Pine, White elm, Gansu Poplar or Russia olive show an exponential relationship with the daily average air temperature or vapour pressure deficit, but the relationship is not so obvious between tree conductance and global radiation. The transpiration process of each tree species is affected by all the observed four environmental variables. The response of tree conductance to different climatic factors changes with tree species. The effect of the same factor to the same tree species is also variable in different growing stages. The sapflow of every tree species is relatively large in later

关键词： sapflow tree conductance leaf area transpiration soil water content climatic variable.

Thermal cracking of n-octodecane and its geochemical significance

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2004年第S1期49卷 79-83页

作者： Yongqiang Xiong Haizhu Zhang Xinhua Geng Ansong Geng chinese Acad Sci State Key Lab Organ Geochem Guangzhou Inst Geochem Guangzhou 510640 Peoples R China

The mechanism of carbon isotopic fractionation for gaseous hydrocarbons is revealed by investigating the residual liquid hydrocarbons in laboratory pyrolysates of n-octodecane. The results indicate that cracking and polymerization in the relatively low temperatures and dispropor-tionation reactions leading to light hydrocarbons and pol-yaromatic hydrocarbons at high temperatures are probably causes for the carbon isotope reversal of gaseous hydrocarbons that is commonly observed in pyrolysis experiments. This study provides significant insight for quantitative modeling of natural gas δ13C values and aid in the identification and assessment of natural gases derived from oil cracking.

关键词： n-octodecane pyrolydsis experiment stable carbon isotope gaseous hydrocarbons residual liquid hydrocarbons.

Constraints on the diversity of crude oil types in the Lunnan Oilfield,Tarim Basin,NW China

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2004年第S1期49卷 19-26页

作者： LU Hong JIA Wanglu XIAO Zhongyao SUN Yongge PENG Ping’an State Key Laboratory of Organic Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Tarim Research Institute of Exploration and Development of Petroleum China PetroleumKuerle 841000China

Hydrocarbons, include heavy oils, normal oils, waxy oils and light oils, condensate oils and gases were all found in Lunnan Oilfield, the occurrences of hydrocarbons with complicated physical properties indicates a complicated distribution of reservoirs. By the drilling data, the distribution pattern had been found that, in plan view, the density of crude oils in the western part is heavier than that of oils in the eastern part in Lunnan region, namely the crude oils were mainly found in the western part while the natural gases were mainly found in the eastern, which shows that an obvious differentiation in the east and west part was presented in the Lunnan region. Furthermore, in vertical view, the light hydrocarbons were mainly found in the Carboniferous reservoir while the heavier hydrocarbons were mainly found in the Ordovician and Triassic reservoirs. By analysis of the semi-logarithm distribution of n-alkanes, biomarker ratios and stable carbon isotopic compositions of crude oils, we have found

关键词： mixing differentiation in eastern and western part oil family light oil high waxy oil semi-logarithm distribution of n-alkanes.

Historical trophic evolutions and their ecological responses from shallow lakes in the middle and lower reaches of the Yangtze River: case studies on Longgan Lake and Taibai Lake

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2006年第Z1期49卷 51-61页

作者： YANG Xiangdong SHEN Ji DONG Xuhui LIU Enfeng WANG Sumin Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China

The evolutions of diatom floras and the total phosphorous (TP) concentrations in the historical period were reconstructed for two lakes, Longgan and Taibai in the middle Yangtze River,based on high resolutional fossil diatom study from two sediment cores and an established regional diatom-TP transfer function. The TP concentration in Longgan Lake changed slightly in the range of 36-62 μg/L and kept its middle trophic level in the past 200 years. The changes of diatom assemblages reflect a macrophyte-dominated history of the lake. During the nineteenth century, the lake TP concentration increased comparatively, corresponding to the increase in abundance of benthic diatoms. The progressive increase of epiphytic diatoms since the onset of the twentieth century indicates the development of aquatic plants, coinciding with the twice drops of water TP level. The TP concentration in Taibai Lake kept a stable status about 50 μg/L before 1953 AD, while diatoms dominated by facultative planktonic Aulacoseira granulata shifted quickly to epiphytic diatom species, indicating a rapid expansion of aquatic vegetation. During 1953-1970 AD, the coverage of aquatic plants decreased greatly inferred by the low abundance of epiphytic diatoms as well as declined planktonic types, and the reconstructed TP concentration shows an obvious rising trend firstly, suggesting the beginning of the lake eutrophication. The lake was in the eutrophic condition after 1970, coinciding with the successive increase of planktonic diatoms. The comparison of the two lakes suggests the internal adjustment and purification function of aquatic plants for nutrients in water. The discrepancy of TP trends in the two lakes after 1960 reflects two different patterns of lake environmental response to human disturbance. Sediments in Taibai Lake clearly recorded the process of lake ecological transformation from the macrophyte-dominated stage to the algae-dominated stage. The limits of TP concentration (68-118 μg/L) i

关键词： diatom, quantitative reconstruction of total phosphorous, trophic evolution, lake ecology, the middle and lower reaches of Yangtze River.

Pool-formation and secondary change of biodegraded viscous oils:case study of reservoir section in the ZhengjiaWangzhuang Oilfield, Jiyang Depression

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2004年第S1期49卷 39-49页

作者： WANG Zhenqi, PENG Ping’an, YU Chiling, LU Hong, ZOU Yanrong, ZHANG Linye & LIU Junmin State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, chinese academy of sciences, Guangzhou 510640, China Department of Earth Science, Yangtze University, Jingzhou 434023, China Research Institute of Geology, Shengli Oilfield Co. Ltd., SINOPEC, Dongying 257015, China State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China Department of Earth Science Yangtze University Jingzhou China Research Institute of Geology Shengli Oilfield Co. Ltd. SINOPEC Dongying China

It is demonstrated by various geochemical indexes that the Zhengjia-Wangzhuang Oilfield with viscous crude oil in the Jiyang Depression has been sourced from the contribution of matured source rocks in the upper Es4. The principal cause leading to the densification of crude oils would be biodegradation, with the degradation level of crude oils being ranked as 2-8; vertically, the biodegradation level increases from the top to bottom of the oil column, with a distinctive biodegradation gradient occurring. Calculated parameters of sterane, terpane and methyl-phenanthrene have indicated that the source-rock’s maturity of crude oils and asphaltic sands ranges from 0.7 to 0.9, and based on the calculation of Easy Ro model, the temperature of hydrocarbon generation in the source rock would be within 120-140℃, which coincides with the measurements of reservoir inclusions. The measured homogenization temperature would represent the generation temperature of the source rock, and be fairly different from that

关键词： viscous oil biodegradation time of pool-formation time of degradation Jiyang Depression.

Kinetic study of the hydrocarbon generation from marine carbonate source rocks characterization of products of gas and liquid hydrocarbon

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2006年第23期51卷 2885-2891页

作者： GENG Xinhua GENG Ansong XIONG Yongqiang LIU Jinzhong ZHANG Haizu ZHAO Qingfang The State Key Laboratory of Organic Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou 510640 China

The kinetic parameters of hydrocarbon generation from the marine carbonate source rocks were determined and calibrated through kinetic simulating experiment. The kinetic parameters of hydrocarbon generation then were extrapolated to geological condition by using the relative software. The result shows that gaseous hydrocarbons (C_1, C_2, C_3, C_(4-5)) were generated in condition of 150℃1.0%13)) and heavy hydrocarbons ( C_(13)^+ ) were generated in condition of 100 ℃ 170 ℃ (0.5%1.5%). A quantitative reference to examine the natural evolution of hydrocarbon of marine carbonate source rocks can be established through the results. It also provides a new method for evaluating the highly mature marine carbonate source rock more reasonably.

关键词：烃相生动力学碳酸盐运动模拟地质情况

Study on the nutrient evolution and its controlling factors of Longgan Lake for the last 200 years

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2006年第Z1期49卷 193-202页

作者： LIU Jian YANG Xiangdong WANG Sumin Key Laboratory of Lake Sedimentation and Environment Chinese Academy of Sciences Nanjing 210008 China Key Laboratory of Lake Sedimentation and Environment Chinese Academy of Sciences Nanjing 210008 China Key Laboratory of Lake Sedimentation and Environment Chinese Academy of Sciences Nanjing 210008 China

Based on the total phosphorous (TP) concentration in sediment core, the TP concentration in lake water quantitatively reconstructed from fossil diatoms and diatom-TP transfer function in the Longgan Lake during the last 200 years, the temperature and precipitation data from meteorological observation for the last 50 years, the temperatures and precipitation sequences of climate simulation for the last 200 years, as well as the amount of the agricultural phosphate fertilizer in Longgan area for nearly 50 years, the characteristic and the law of the nutrient status evolution were analyzed, and the influence of the climatic factor, the anthropologic factor and the aquatic biology factor on the nutrient status evolution and its mechanism were discussed for the Longgan Lake during the last 200 years. The results showed that, in the nearly 200 years, the TP concentration in the sediment core of the Longgan Lake gradually increased, its range of variation was situated between 330-580 mg/kg, the mean value was 388 mg/kg, a nearly 30-year vibration adjustment period existed at 1950 around. The TP concentration in lake water changed in a different way. Before 1950, it had a slow increasing tendency in fluctuated background, to 1950 around it reached up to the mean value (52.18 μg/L), and vibrated and adjusted around the mean value, then it fast declined, its change range was situated between 37.75-62.33 μg/L. The analyses indicated that, in the centennial time scale, the climate change was the main controlling factor, while in the decadal time scale in the recent 50 years, human activities were the leading factors for the nutrient status evolution of the Longgan Lake. 60% of the variability of the TP concentration in the sediments and 57% of that in lake water were due to human activities. The differentiation between phosphorus concentration in the sediment and in the lake water reflected the response processes and the adjustment abilities of the lake aquatic ecosystems to th

关键词： Longgan Lake, nutrient evolution, controlling factor, climate, human activities.

Deduction and application of generalized Euler formula in topological relation of geographic information system (GIS)

在线全文

学校读者我要写书评

暂无评论

Science China Earth sciences 2004年第8期47卷 749-759页

作者： ZHANG Shuqing1, ZHANG Junyan1,2 & ZHANG Bai1 Northeast Institute of Geography and Agricultural Ecology, chinese academy of sciences, Changchun 130012, China Northeast Design Institute of China City Planning and Engineering, Changchun 130012, China Northeast Institute of Geography and Agricultural Ecology Chinese Academy of Sciences Changchun China Northeast Design Institute of China City Planning and Engineering Changchun China

By combining geographic information system (GIS), a new conception of “group” in which covers the complex connected region is introduced in the paper. Based on the conception of group, a generalized Euler formula and its properties are deduced and proved. The paper also describes the mathematical principles of generating topological information of polygon in GIS maps and the methods for checking up the veracity of topological relations of the map with Euler formula and general Euler formula. We have also obtained the quantitative relations among real nodes, chains, islands and groups with the formulas. At the same time, the paper introduces Whole Sphere Stereographic (WSS) projection into the GIS, and defines a new conception of “sea”. The deduction of general Euler formula and the introduction of WSS projection to GIS have developed new ways of delineating GIS topological models from plane to sphere and even constructing three dimensional (3-D) topological models.

关键词： Euler formula,general Euler formula,geographic information system,topological relation.

Static opaque chamber-based technique for determination of net exchange of CO_2 be-tween terrestrial ecosystem and atmosphere

在线全文

学校读者我要写书评

暂无评论

chinese Science Bulletin 2004年第4期49卷 381-388页

作者： ZOUJianwen HUANGYao ZHENGXunhua WANGYuesi CHENYuquan CollegeofResourcesandEnvironmentalsciences NanjingAgriculturalUniversityNanjing210095China InstituteofAtmosphericPhysics Beijing100029China AgriculturalResourceandEnvironmentResearchCenter JiangsuAcademyofAgriculturalSciencesNanjing210014China

Terrestrial carbon cycling is one of the hotspots in global change issues. In this paper, we presented the ra-tionale for determination of net exchange of CO2 between terrestrial and the atmosphere (NEE) and the methods for measuring several relevant components. Three key processes for determination of NEE were addressed, including the separation of shoot autotrophic respiration from total CO2 emissions of the ecosystem, the partition of root respiration from soil CO2 efflux, and the quantification of rhizodeposi-tion C from NPP. With an understanding of the processes involved in the CO2 exchange between terrestrial and the atmosphere, we estimated NEE of rice ecosystem in Nanjing based on field measurements of CO2 emissions and several relevant biotic components as well as abiotic factors. The field measurements of CO2 emissions were made over the rice-growing seasons in 2001 and 2002 with the static opaque chamber method. Calculations indicated that the seasonal pattern of NEE is comparable for two seasons. Either net carbon emission or fractional carbon fixation occurred dur-ing 3 weeks after rice transplanting and thereafter net car-bon fixation appeared with an increasing trend as rice grow-ing. Higher net carbon fixation occurred in the rice devel-opmental period from elongating to heading. A decline trend in the fixation was documented after rice heading. The mean daily NEE was -6.06 gC·m-2 in 2001 season and -7.95 gC·m-2 in 2002 season, respectively. These values were comparable to the results obtained by Campbell et al. who made field measurements with the Bowen ratio-energy bal-ance technique in irrigated rice, Texas USA. Moreover, the mean daily NEE in this study was also comparable to the values obtained from a Japanese rice paddy with the eddy covariance method under the similar water regime, either drainage course or waterlogged. It is concluded that NEE determined by the static opaque chamber method is compa-rable and in agreement with those measured

关键词：二氧化碳陆地生态系统碳循环大气层