Horizontal and vertical variations of daily average CO 2 concentration above the wetland surface were studied in Xianghai National Nature Reserve of China in August, 2000 The primary purpose was to study spatial distr...Horizontal and vertical variations of daily average CO 2 concentration above the wetland surface were studied in Xianghai National Nature Reserve of China in August, 2000 The primary purpose was to study spatial distribution characteristics of CO 2 concentration on the four levels of height(0 1 m, 0 6 m, 1 2 m and 2 m) and compare the differences of CO 2 concentration under different land covers. Results showed that daily average CO 2 concentration above wetland surface in Xianghai National Natural Reserve was lower than that above other wetlands in northeast China as well as the worldwide average, suggesting that Xianghai wetland absorbed CO 2 in August and acted as “sink” of CO 2 The horizontal variations on the four levels of height along the latitude were distinct, and had the changing tendency of “decreasing after increasing” with the increase of height. The areas with obvious variations were consistent on different levels of height, and those with the highest variations appeared above surface of shore, sloping field, Typha wetland and Phragmites wetland; the vertical variations were greatly different, with the higher variations in Phragmites wetland and Typha wetland, and the lands near the shore and the sloping field with the lower variations. Spatial variations of daily average CO 2 concentrations above wetland surface were affected by surface qualities and land covers.展开更多
Pinus Syvestfiformis is an important species as an indicator of global climate changes in Changbai Mountain, China. The water use efficiency (WUE) of this species (11 -year old ) was studied on response to elevated Co...Pinus Syvestfiformis is an important species as an indicator of global climate changes in Changbai Mountain, China. The water use efficiency (WUE) of this species (11 -year old ) was studied on response to elevated Co, concentration at 500±μLL' L-1 by directly injecting CO2 into the canopy under natural condition in 1998-1999. The results showed that the elevated Co, concentration reduced averagely stomatal opening, stomatal conductance and stomatal density to 78%, 80% and 87% respectively, as compared to normal ambient. The elevated Co, reduced the transpiration and enhances the water use efficiency (WUE) of plant.展开更多
Objective To investigate effects of different high CO_2 concentrations on the development of 2-cell mouse embryos in vitro Methods At levels of 5% CO_2 (control group), 5.7% CO_2, 6.0% CO_2 and 15% CO_2, embryos w...Objective To investigate effects of different high CO_2 concentrations on the development of 2-cell mouse embryos in vitro Methods At levels of 5% CO_2 (control group), 5.7% CO_2, 6.0% CO_2 and 15% CO_2, embryos were incubated in drops with CZB medium, respectively, and the drops were covered by paraffin oil which was treated with three-distilled water. In addition, at the level of 15% CO_2, there were another two groups, in which paraffin oil was treated with phosphate-buffered saline (PBS) solution or the drops were uncovered. The development of embryos in all stages was noted. Results The developmental rates of blastocysts in five experimental groups were significantly lower than that of the control group (P<0.01). At the level of 5.7% CO_2, the developmental rate of blastocysts was 4.3%, and those of other experimental groups were 0. At the levels of 5.7% and 6.0% CO_2, embryos were blocked in the 2-cell or the 4-cell stage, and no significant difference was showed between the two groups (P>0.05). At the level of 15% CO_2, 15% embryos developed in the 4-cell stage with irregular blastomere and degenerated quickly in the group which paraffin oil was treated with distilled water; 2.2% embryos developed in the 4-cell stage in the group which paraffin oil was treated with PBS and the rest stagnated in the 2-cell stage. Conclusions High CO_2 concentrations had toxic effect on the in vitro development of 2-cell mouse embryos, and was responsible for the inhibition of the embryos. It is important for the development of embryos in vitro to detect strictly CO_2 concentration.展开更多
An experiments were carried out with treatments differing in nitrogen supply (0, 5 and 15 g N/m^2) and CO2 levels (350 and 700 μmol/mol) using OTC (open top chamber) equipment to investigate the biomass of Cala...An experiments were carried out with treatments differing in nitrogen supply (0, 5 and 15 g N/m^2) and CO2 levels (350 and 700 μmol/mol) using OTC (open top chamber) equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO2 concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO2 concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO2 elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO2 concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply (15 g N/m^2). Elevated CO2 concentration also increased the allocation of biomass and carbon in root. Under elevated CO2 concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon (10.6%) 〉 dissolved organic carbon (7.5%) 〉 labile oxidable carbon (6.6%) 〉 carbohydrate carbon (4.1%). Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO2 concentration.展开更多
Hoagland's solution was used as water culture medium to study the effect of CO2 concentration on nitrate metabolism of wheat under natural light and light-shaded conditions. NO3^-N, NH4^+-N, nitrate reductase activi...Hoagland's solution was used as water culture medium to study the effect of CO2 concentration on nitrate metabolism of wheat under natural light and light-shaded conditions. NO3^-N, NH4^+-N, nitrate reductase activity, total uptake N by wheat plants during solution cultural period and total N in plants were determined for comprehensive evaluation of the effect. Results showed that under both natural light and light-shaded conditions, addition of CO2 increased NO3^-N uptake and its assimilative capabilities by plants. However, there were some difference between shoots and roots. With increase of CO2 concentration, the concentration of NO3^-N and NH4^+-N as well as nitrate reductase activity were all decreased for shoots while the difference was not so distinct in roots, and the nitrate reductase activity was not decreased, but increased. Since NO3^-N uptake by plants from the solution and the total N in plants were much higher by CO2 addition, it may be concluded that addition of CO2 has resulted in rise of nitrate absorption, assimilation and metabolism of wheat.展开更多
There is limited information available on CO2 concentration and flux over marsh. The objective of this work was to characterize CO2 concentration and flux within and above marsh plant (Cares lasiocarpa Ehrh. and C. ps...There is limited information available on CO2 concentration and flux over marsh. The objective of this work was to characterize CO2 concentration and flux within and above marsh plant (Cares lasiocarpa Ehrh. and C. pseudoucuaica F. Schm) canopy at heights 0. 5, 1. 0 and 1. 5 m.CO2 concentration was measured sequentially every 3 bars by using an infrared gas analyzer. Soil and air temperature, wind speed, net radiation and soil heat flux were also measured simultaneously. Extremely drily minimum and maximum CO2 concentration rangal from 250 to 754 μmd/mol for the 4-year work. The typical minimum and maximum values ranged from 314 to 464 μmol/mol at the height of marsh plant (about 0. 5 m) during the fruiting perioed and mature date. The seasonal changes in CO2 concentration show that the minimum CO2 concentration occurred in the fruiting period and mature date, and both of their minimum values were 314 μmol/mol. This illustrates that CO2 consumed by photosynthesis was stable during the period. The flux of CO2 can be thought as a turbulent diffusion phenomenon. By micrometeorological methods, the diurnal CO2 fluxes were measured in the flowering peried, fruiting period, early mature date, late mature date and yellow-ripe stage. Their values were -0. 18, 38. 15,24. 13, 10. 9 and 4. 91 μmol/mol respectively.展开更多
Atmospheric CO2 concentration (CC) near land surface and meteorological variables have been measured at four sites, named Yeniugou (alpine meadow and permafrost), Xishui (mountainous forest), Linze (oasis edge...Atmospheric CO2 concentration (CC) near land surface and meteorological variables have been measured at four sites, named Yeniugou (alpine meadow and permafrost), Xishui (mountainous forest), Linze (oasis edge) and Ejina (lower desert), respectively, in Heihe River Basin, northwest China. The results showed that, the half hourly CC at night was larger than in daytime, and the daily averaged CC was the largest in winter. The averaged CC of 932 d at the Linze was about 418 ppm, was about 366 ppm in the 762 d at the Ejina. In the same period from September 23 to November 9, 2004, the averaged CC was about 625,334, 436 and 353 ppm, at Yeniugou, Xishui, Linze and Ejina, respectively. The linear relationship between daily averaged CC and air temperature T was negative, between CC and relative humidity (RH) was positive. The linear CC-atmospheric pressure (A P) relationship was negative at the Linze and Yeniugou, was positive at the Ejina. The relationship between CC and global radiation R was exponent, and soil temperature Ts was negative linear, and soil water content was complex. The correlation between CC and wind speed was not existent. Using meteorological variables together to simulate CC, could give good results.展开更多
Using the Differential Absorption Lidar (DIAL) technique, two types of approaches, namely, reflection from retroreflector / topographic target and backscatter from atmosphere, are available for studying remotely the a...Using the Differential Absorption Lidar (DIAL) technique, two types of approaches, namely, reflection from retroreflector / topographic target and backscatter from atmosphere, are available for studying remotely the atmospheric NO, concentration. The Argon ion lidar system at the Indian Institute of Tropical Meteorology (IITM), Pune, India has been used for the measurements by following both the path-averaged and range-resolved approaches. For the former, a topographic target (hill) is used for determining path-averaged surface concentration. In the latter, spectral properties of atmospheric attenuation is used for making range-resolved measurements in the surface layer. The results of the observations collected by following both approaches are presented. The average surface NO2 concentration was found to vary between 0.01 and 0.105 ppm and the range-resolved measurements exhibited higher values suggesting treatment of the lidar data for scattering and extinction effects due to atmospheric aerosols and air molecules, and atmospheric turbulence. Certain modifications that are suggested to the experimental set-up, data acquisition and analysis to improve the measurements are briefly described.展开更多
[ Objective] The study aimed to discuss the effects of the adjustment of energy structure on daily average concentration of NO2 in different regions of Urumqi city in winter. [ Method] The changes of daily average con...[ Objective] The study aimed to discuss the effects of the adjustment of energy structure on daily average concentration of NO2 in different regions of Urumqi city in winter. [ Method] The changes of daily average concentration of NO2 in different areas of Urumqi City from January to February ( NO2 pollution was most serious) before and after the implementation of the project "changing coal to gas" were analyzed. [ Result] After the implementation of the project, daily average concentration of NO2 in different areas of Urumqi City was increased due to the rapid increase of ve- hicle quantity, but there were certain differences in the increase among various regions. From south to north, daily average concentration of NO2 in winter was decreased gradually, that is, daily average concentration of NO2 was the highest in the south area, while in the north area, it didn't change significantly before and after the implementation of the project, but it was still high. Therefore, the local government should pay more attention to pollution NO2 during environmental management process. [ Conclusion] The research could provide scientific references for the control of atmospheric pollution in future.展开更多
The relationship between the stomatal density of five woody plants endemic to China, i.e. Eucommia ulmoides, Quercus liaotungensis, Q. glandulifera var. brevipetiolata, Cyclocarya paliurus and Ficus heteromorpha, and ...The relationship between the stomatal density of five woody plants endemic to China, i.e. Eucommia ulmoides, Quercus liaotungensis, Q. glandulifera var. brevipetiolata, Cyclocarya paliurus and Ficus heteromorpha, and the atmospheric CO-2 concentrations was studied by observations on leaves of the herbarium-stored specimens(1920s-1990s). The results showed that the stomatal density in Eucommia ulmoides, Quercus liaotungensis and Q. glandulifera% var. brevipetiolata decreased significantly in response to the elevated atmospheric CO-2 concentrations, while in Cyclocarya paliurus it decreased slightly and in Ficus heteromorpha there were no responses.展开更多
Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Th...Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution.展开更多
Using recently developed methods for root research, an investigation initiated concerning effects of doubled atmospheric CO<sub>2</sub> concentration on root surface area and infection of vesicular-arbuscu...Using recently developed methods for root research, an investigation initiated concerning effects of doubled atmospheric CO<sub>2</sub> concentration on root surface area and infection of vesicular-arbuscular mycorrhizal (VAM) fungi in seedlings of maize, wheat and soybean. Results showed that doubled CO<sub>2</sub> concentration significantly extended root system surface area and promoted VAM fungal infection intensity and viability. However, interspecific variation existed in these responses. It is suggested that plant community succession would be changed due to altered characteristics of roots among species in the future climate.展开更多
In-situ measurement of atmospheric CO_2 was made at the top of the Waliguan Mountain(36°17′N,100°54′E,3816 m asl).where the air is not directly affected by the local anthropogenic and natural sources,by us...In-situ measurement of atmospheric CO_2 was made at the top of the Waliguan Mountain(36°17′N,100°54′E,3816 m asl).where the air is not directly affected by the local anthropogenic and natural sources,by using a nondispersive infrared(NDIR)analyzer and following the procedures proposed by WMO.The CO_2 in the flask samples collected on the mountain was also analyzed in a laboratory.The measurements uncover the daily,monthly and seasonal variabilities and the baseline level of the CO_2 in the air over the“clean”area of Chinese hinterland.Results suggest that the CO_2 concentration over the East Asia continent has evident periodical variation,similar to that of global distribution.In 1992,an annual mean baseline CO_2 concentration of 356.4 ppm over the continent was obtained.The annual mean val- ue was 357.2 ppm for 1993.Some relationships between the CO_2 concentration at Waliguan and the weather conditions, especially,wind speed and direction are found through the observation.展开更多
To reveal and quantify the interactive effects of drought stresses and elevated CO2 concentration [CO2] on photochemistry efficiency of cucumber seedlings, the portable chlorophyll meter was used to measure the chloro...To reveal and quantify the interactive effects of drought stresses and elevated CO2 concentration [CO2] on photochemistry efficiency of cucumber seedlings, the portable chlorophyll meter was used to measure the chlorophyll content, and the Imaging-PAM was used to image the chlorophyll fluorescence parameters and rapid light response curves (RLC) of leaves in two adjacent greenhouses. The results showed that chlorophyll content of leaves was reduced significantly with drought stress aggravated. Minimal fluorescence (Fo) was increased while maximal quantum yield of PSII (Fv/Fm) decreased significantly by severe drought stress. The significant decrease of effective quantum yield of PSII (Y(Ⅱ)) accompanied by the significant increase of quantum yield of regulated energy dissipation (Y(NPQ)) was observed under severe drought stress condition, but there was no change of quantum yield of nonregulated energy dissipation (Y(NO)). We detected that the coefficient of photochemical quenching (qP) decreased, and non-photochemical quenching (NPQ) increased significantly under severe drought stress. Furthermore, we found that maximum apparent electron transport rate (ETRmax) and saturating photosynthetically active radiation (PPFDsat) decreased significantly with drought stress aggravated. However, elevated [CO2] significantly increased FvlFm, qP and PPFDsat, and decreased NPQ under all water conditions, although there were no significant effects on chlorophyll content, Fo, Y(Ⅱ), Y(NPQ), Y(NO) and ETRmax. Therefore, it is concluded that CO2-fertilized greenhouses or elevated atmospheric [CO2] in the future could be favorable for cucumber growth and development, and beneficial to alleviate the negative effects of drought stresses to a certain extent.展开更多
A novel and multi-disciplinary subject involving the relationships between changes in atmospheric CO<sub>2</sub> concentration throughout the geological history and features of plant anatomy is reviewed. P...A novel and multi-disciplinary subject involving the relationships between changes in atmospheric CO<sub>2</sub> concentration throughout the geological history and features of plant anatomy is reviewed. Particular attention will be given to stomatal parameters (stomatal density and stomatal index) which are recorded at a cellular level in fossil plants and the relationships of these observable parameters to earth life history and global environmental change. Trends of atmospheric CO<sub>2</sub> concentrations during the Phanerozoic period are briefly introduced and recent conceptual advances in understanding the causal mechanisms for changes in stomatal parameters of land vascular plants are considered, In addition, some of the inherent problems and limitations of this kind of work are discussed and future research directions are presented.展开更多
Solenites vimineus (Phillips) Harris (Ginkgophyta) specimens with well-preserved cuticles were collected from five different beds in the oil shale member of the Middle Jurassic Yaojie Formation in the Yaojie Basin, Ga...Solenites vimineus (Phillips) Harris (Ginkgophyta) specimens with well-preserved cuticles were collected from five different beds in the oil shale member of the Middle Jurassic Yaojie Formation in the Yaojie Basin, Gansu Province, northwestern China. Gross morphology and fine structures of the fossil leaves were studied, and stomatal parameters were analyzed, according to which, the paleoatmospheric CO2 concentration can be deduced as 1512-1896 ppm that would have caused an increase in mean temperature of about 6.5-7.4℃. Carbon isotopes from the fossils indicate that the carbon isotopic discrimination and water use efficiency (WUE) of S. vimineus were raised nearly obtaining the ideal physiologic state in increased CO2 concentrations and temperature conditions, suggesting that S. vimineus records the paleoenvironmental information of the Middle Jurassic Yaojie Basin and can be used for environmental reconstruction.展开更多
Eu3+ doped SiO2 nano-crystalline glasses were prepared by sol-gel method. The broad peak of XRD pattern indicates an amorphous SiO2 matrix. The affection of anneal time and anneal temperatures on photoluminescence (PL...Eu3+ doped SiO2 nano-crystalline glasses were prepared by sol-gel method. The broad peak of XRD pattern indicates an amorphous SiO2 matrix. The affection of anneal time and anneal temperatures on photoluminescence (PL) properties of SiO2 glass under different Eu doping concentration were studied systematically. It is found that the optimized anneal time is about 3 h. The excitation spectra of 2% Eu3+ doped SiO2 glass powder were measured under various anneal temperatures, and the optimized anneal temperature is observed around 700℃. The fluorescence-quenching effect can be observed in the emission spectra when the annealing temperature exceeds 700℃. The emission spectra of different molar ratio dopants were measured at an annealed temperature of 500℃, and the concentration-quenching phenomenon has also been observed in SiO2 glass powder when the molar ratio of Eu3+ ion exceeds 3% . The result shows that the PL intensity approaches its maximum when the molar ratio of Eu3+ ions in the sample is about 3% . In addition, a comparatively stronger emission spectrum at wavelength of 703 nm which is corresponding to the energy transition 5D0→7F4 of Eu ions is also obtained.展开更多
THE seasonal variance of soil CO<sub>2</sub> concentration with depth in soil profile was widely studied. Few similarresearches on this topic have been done in karst area which comprises 15% global terrest...THE seasonal variance of soil CO<sub>2</sub> concentration with depth in soil profile was widely studied. Few similarresearches on this topic have been done in karst area which comprises 15% global terrestrial area. In thisnote, the research results about the seasonal and daily soil CO<sub>2</sub> concentration variance in karst area arereported. The soil gases were collected respectively by the sampling device at 200, 5,0, -5, -10,-15, -25, -35 and -45 cm from the land surface in meadow soil profile described by Zheng andlocated in the Hongfeng lake area in the central Guizhou Plateau which lies in the central East-Asia karstarea. Sampling time is in the morning, midday and at night in April, August and November, 1998 aswell as in January, 1999, respectively. Concentrations (volume percent) of CO<sub>2</sub> in soil gas samples展开更多
The Tibetan Plateau is characterized by lower atmospheric pressure, lower air temperature and high daily and seasonal variation due to high elevation. The photosynthesis of plants is significantly influenced by these ...The Tibetan Plateau is characterized by lower atmospheric pressure, lower air temperature and high daily and seasonal variation due to high elevation. The photosynthesis of plants is significantly influenced by these alpine environmental factors. Apparent quantum yield (αA) is one of the basic parameters of photosynthesis and mass production. Its accuracy determination is of significance to model photosynthesis of C3 plants and global change on the plateau. In the Lhasa Plateau Ecological Station with 65.4 kPa of atmospheric pressure at an elevation of 3688 m, Li-Cor 6400 portable photosynthesis system was used to measure light response curves of winter wheat in different temperatures and intercellular CO2 concentration (Ci).The slope of light response curve in weak light area of PFD from 0 to 150 μmol m-2 S-1 was used to evaluate the value of αA. The dependence of αA on temperature and intercellular concentration was analyzed. In 30℃, the average value of αAWaS 0.0476 ± 0.0038. It is not quite different from the values in low elevation areas. αA is influenced both by temperature and by the ratio of CO2and O2 partial pressure ([CO2]/[O2]). The measured values in the previous study were much lower.This might be due to systematic errors from instrument and data processing methods. The values of αA decreased linearly with temperature. It decreased 0.0007 in every 1℃ increase of temperature. The decrease slope is similar to those of C3 plants in the previous researches. While [O2] is constant, αA increases with Ciwith a hyperbolic relationship. In comparison with low elevation areas, the αA on the Tibetan Plateau is more sensitive to increase of CO2.展开更多
Successive filtration and comparison show that the stratosphere air temperature in 10 hPa-layer of the Northern Hemisphere (NH) in July continuously increases,which is associated to the increases in greenhouse gases...Successive filtration and comparison show that the stratosphere air temperature in 10 hPa-layer of the Northern Hemisphere (NH) in July continuously increases,which is associated to the increases in greenhouse gases mostly CO2,volcanic activities,and solar activity,demonstrating the follows.(a) The increase in CO2 concentration is largely consistent with that of the stratosphere air temperature in 10 hPa-layer of the NH in July.However,the increase in the air temperature is not in a linear pattern,during which several cooling events interrupt.The cooling events between late 1960s and late 1970s are remarkable ones and so is the one before mid 1990s.Analysis shows that these events are induced by volcanic activities and solar activity.(b) The CO2-free variation in the stratosphere air temperature in 10 hPa-layer of the NH is consistent with that of the solar magnetic index.The wave crests and wave troughs of the two curves are consistent in phase,and the curve of solar magnetic index leads the other slightly.In other words,when the solar magnetic pole is southward,a warming in the NH stratosphere corresponds;and on the contrary,the northward solar magnetic pole corresponds to a cooling event.The variation in solar magnetic polarity strongly impacts the variation in the stratosphere temperature.展开更多
文摘Horizontal and vertical variations of daily average CO 2 concentration above the wetland surface were studied in Xianghai National Nature Reserve of China in August, 2000 The primary purpose was to study spatial distribution characteristics of CO 2 concentration on the four levels of height(0 1 m, 0 6 m, 1 2 m and 2 m) and compare the differences of CO 2 concentration under different land covers. Results showed that daily average CO 2 concentration above wetland surface in Xianghai National Natural Reserve was lower than that above other wetlands in northeast China as well as the worldwide average, suggesting that Xianghai wetland absorbed CO 2 in August and acted as “sink” of CO 2 The horizontal variations on the four levels of height along the latitude were distinct, and had the changing tendency of “decreasing after increasing” with the increase of height. The areas with obvious variations were consistent on different levels of height, and those with the highest variations appeared above surface of shore, sloping field, Typha wetland and Phragmites wetland; the vertical variations were greatly different, with the higher variations in Phragmites wetland and Typha wetland, and the lands near the shore and the sloping field with the lower variations. Spatial variations of daily average CO 2 concentrations above wetland surface were affected by surface qualities and land covers.
文摘Pinus Syvestfiformis is an important species as an indicator of global climate changes in Changbai Mountain, China. The water use efficiency (WUE) of this species (11 -year old ) was studied on response to elevated Co, concentration at 500±μLL' L-1 by directly injecting CO2 into the canopy under natural condition in 1998-1999. The results showed that the elevated Co, concentration reduced averagely stomatal opening, stomatal conductance and stomatal density to 78%, 80% and 87% respectively, as compared to normal ambient. The elevated Co, reduced the transpiration and enhances the water use efficiency (WUE) of plant.
基金This work was supported by the Natural Science Foundation of Guangdong Province,China
文摘Objective To investigate effects of different high CO_2 concentrations on the development of 2-cell mouse embryos in vitro Methods At levels of 5% CO_2 (control group), 5.7% CO_2, 6.0% CO_2 and 15% CO_2, embryos were incubated in drops with CZB medium, respectively, and the drops were covered by paraffin oil which was treated with three-distilled water. In addition, at the level of 15% CO_2, there were another two groups, in which paraffin oil was treated with phosphate-buffered saline (PBS) solution or the drops were uncovered. The development of embryos in all stages was noted. Results The developmental rates of blastocysts in five experimental groups were significantly lower than that of the control group (P<0.01). At the level of 5.7% CO_2, the developmental rate of blastocysts was 4.3%, and those of other experimental groups were 0. At the levels of 5.7% and 6.0% CO_2, embryos were blocked in the 2-cell or the 4-cell stage, and no significant difference was showed between the two groups (P>0.05). At the level of 15% CO_2, 15% embryos developed in the 4-cell stage with irregular blastomere and degenerated quickly in the group which paraffin oil was treated with distilled water; 2.2% embryos developed in the 4-cell stage in the group which paraffin oil was treated with PBS and the rest stagnated in the 2-cell stage. Conclusions High CO_2 concentrations had toxic effect on the in vitro development of 2-cell mouse embryos, and was responsible for the inhibition of the embryos. It is important for the development of embryos in vitro to detect strictly CO_2 concentration.
基金supported by the Chinese Academy of Sciences (No KZCX2-YW-309)the National Basic Research Program (973) of China (No 2004CB418507)
文摘An experiments were carried out with treatments differing in nitrogen supply (0, 5 and 15 g N/m^2) and CO2 levels (350 and 700 μmol/mol) using OTC (open top chamber) equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO2 concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO2 concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO2 elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO2 concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply (15 g N/m^2). Elevated CO2 concentration also increased the allocation of biomass and carbon in root. Under elevated CO2 concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon (10.6%) 〉 dissolved organic carbon (7.5%) 〉 labile oxidable carbon (6.6%) 〉 carbohydrate carbon (4.1%). Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO2 concentration.
基金the projects(30230230 ,30070429)supported by the National Natural Science Foundation of China(NSFC) the project(G1999011707)supported by the National Key Basic Research Support Funds(NKBRSF)the NSFC and the NKBRSF for their kindness of supporting theseprojects.
文摘Hoagland's solution was used as water culture medium to study the effect of CO2 concentration on nitrate metabolism of wheat under natural light and light-shaded conditions. NO3^-N, NH4^+-N, nitrate reductase activity, total uptake N by wheat plants during solution cultural period and total N in plants were determined for comprehensive evaluation of the effect. Results showed that under both natural light and light-shaded conditions, addition of CO2 increased NO3^-N uptake and its assimilative capabilities by plants. However, there were some difference between shoots and roots. With increase of CO2 concentration, the concentration of NO3^-N and NH4^+-N as well as nitrate reductase activity were all decreased for shoots while the difference was not so distinct in roots, and the nitrate reductase activity was not decreased, but increased. Since NO3^-N uptake by plants from the solution and the total N in plants were much higher by CO2 addition, it may be concluded that addition of CO2 has resulted in rise of nitrate absorption, assimilation and metabolism of wheat.
文摘There is limited information available on CO2 concentration and flux over marsh. The objective of this work was to characterize CO2 concentration and flux within and above marsh plant (Cares lasiocarpa Ehrh. and C. pseudoucuaica F. Schm) canopy at heights 0. 5, 1. 0 and 1. 5 m.CO2 concentration was measured sequentially every 3 bars by using an infrared gas analyzer. Soil and air temperature, wind speed, net radiation and soil heat flux were also measured simultaneously. Extremely drily minimum and maximum CO2 concentration rangal from 250 to 754 μmd/mol for the 4-year work. The typical minimum and maximum values ranged from 314 to 464 μmol/mol at the height of marsh plant (about 0. 5 m) during the fruiting perioed and mature date. The seasonal changes in CO2 concentration show that the minimum CO2 concentration occurred in the fruiting period and mature date, and both of their minimum values were 314 μmol/mol. This illustrates that CO2 consumed by photosynthesis was stable during the period. The flux of CO2 can be thought as a turbulent diffusion phenomenon. By micrometeorological methods, the diurnal CO2 fluxes were measured in the flowering peried, fruiting period, early mature date, late mature date and yellow-ripe stage. Their values were -0. 18, 38. 15,24. 13, 10. 9 and 4. 91 μmol/mol respectively.
文摘Atmospheric CO2 concentration (CC) near land surface and meteorological variables have been measured at four sites, named Yeniugou (alpine meadow and permafrost), Xishui (mountainous forest), Linze (oasis edge) and Ejina (lower desert), respectively, in Heihe River Basin, northwest China. The results showed that, the half hourly CC at night was larger than in daytime, and the daily averaged CC was the largest in winter. The averaged CC of 932 d at the Linze was about 418 ppm, was about 366 ppm in the 762 d at the Ejina. In the same period from September 23 to November 9, 2004, the averaged CC was about 625,334, 436 and 353 ppm, at Yeniugou, Xishui, Linze and Ejina, respectively. The linear relationship between daily averaged CC and air temperature T was negative, between CC and relative humidity (RH) was positive. The linear CC-atmospheric pressure (A P) relationship was negative at the Linze and Yeniugou, was positive at the Ejina. The relationship between CC and global radiation R was exponent, and soil temperature Ts was negative linear, and soil water content was complex. The correlation between CC and wind speed was not existent. Using meteorological variables together to simulate CC, could give good results.
文摘Using the Differential Absorption Lidar (DIAL) technique, two types of approaches, namely, reflection from retroreflector / topographic target and backscatter from atmosphere, are available for studying remotely the atmospheric NO, concentration. The Argon ion lidar system at the Indian Institute of Tropical Meteorology (IITM), Pune, India has been used for the measurements by following both the path-averaged and range-resolved approaches. For the former, a topographic target (hill) is used for determining path-averaged surface concentration. In the latter, spectral properties of atmospheric attenuation is used for making range-resolved measurements in the surface layer. The results of the observations collected by following both approaches are presented. The average surface NO2 concentration was found to vary between 0.01 and 0.105 ppm and the range-resolved measurements exhibited higher values suggesting treatment of the lidar data for scattering and extinction effects due to atmospheric aerosols and air molecules, and atmospheric turbulence. Certain modifications that are suggested to the experimental set-up, data acquisition and analysis to improve the measurements are briefly described.
基金Supported by National Natural Science Foundation(41161074)
文摘[ Objective] The study aimed to discuss the effects of the adjustment of energy structure on daily average concentration of NO2 in different regions of Urumqi city in winter. [ Method] The changes of daily average concentration of NO2 in different areas of Urumqi City from January to February ( NO2 pollution was most serious) before and after the implementation of the project "changing coal to gas" were analyzed. [ Result] After the implementation of the project, daily average concentration of NO2 in different areas of Urumqi City was increased due to the rapid increase of ve- hicle quantity, but there were certain differences in the increase among various regions. From south to north, daily average concentration of NO2 in winter was decreased gradually, that is, daily average concentration of NO2 was the highest in the south area, while in the north area, it didn't change significantly before and after the implementation of the project, but it was still high. Therefore, the local government should pay more attention to pollution NO2 during environmental management process. [ Conclusion] The research could provide scientific references for the control of atmospheric pollution in future.
文摘The relationship between the stomatal density of five woody plants endemic to China, i.e. Eucommia ulmoides, Quercus liaotungensis, Q. glandulifera var. brevipetiolata, Cyclocarya paliurus and Ficus heteromorpha, and the atmospheric CO-2 concentrations was studied by observations on leaves of the herbarium-stored specimens(1920s-1990s). The results showed that the stomatal density in Eucommia ulmoides, Quercus liaotungensis and Q. glandulifera% var. brevipetiolata decreased significantly in response to the elevated atmospheric CO-2 concentrations, while in Cyclocarya paliurus it decreased slightly and in Ficus heteromorpha there were no responses.
基金Supported by National Natural Science Foundation of China (Grant No. 40775078)National Non-profit Research Project to Serve the Public Interest (Grant No. GYHY200806026)International S & T Cooperation Program of MOST(Grant No. 2007DFA20650)
文摘Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concen- tration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution.
文摘Using recently developed methods for root research, an investigation initiated concerning effects of doubled atmospheric CO<sub>2</sub> concentration on root surface area and infection of vesicular-arbuscular mycorrhizal (VAM) fungi in seedlings of maize, wheat and soybean. Results showed that doubled CO<sub>2</sub> concentration significantly extended root system surface area and promoted VAM fungal infection intensity and viability. However, interspecific variation existed in these responses. It is suggested that plant community succession would be changed due to altered characteristics of roots among species in the future climate.
基金This study is supported by the National Science and Technology Commission of China.
文摘In-situ measurement of atmospheric CO_2 was made at the top of the Waliguan Mountain(36°17′N,100°54′E,3816 m asl).where the air is not directly affected by the local anthropogenic and natural sources,by using a nondispersive infrared(NDIR)analyzer and following the procedures proposed by WMO.The CO_2 in the flask samples collected on the mountain was also analyzed in a laboratory.The measurements uncover the daily,monthly and seasonal variabilities and the baseline level of the CO_2 in the air over the“clean”area of Chinese hinterland.Results suggest that the CO_2 concentration over the East Asia continent has evident periodical variation,similar to that of global distribution.In 1992,an annual mean baseline CO_2 concentration of 356.4 ppm over the continent was obtained.The annual mean val- ue was 357.2 ppm for 1993.Some relationships between the CO_2 concentration at Waliguan and the weather conditions, especially,wind speed and direction are found through the observation.
基金Supported by the National Key Project of Scientific and Technical Supporting Programs from Ministry of Science & Technology of China (2006BAD28B07-5)the Hi-Tech Research and Development (863) Program of China(2001AA247012)the Innovation in Graduate Education Plan of Northwest A&F University (05YCH013).
文摘To reveal and quantify the interactive effects of drought stresses and elevated CO2 concentration [CO2] on photochemistry efficiency of cucumber seedlings, the portable chlorophyll meter was used to measure the chlorophyll content, and the Imaging-PAM was used to image the chlorophyll fluorescence parameters and rapid light response curves (RLC) of leaves in two adjacent greenhouses. The results showed that chlorophyll content of leaves was reduced significantly with drought stress aggravated. Minimal fluorescence (Fo) was increased while maximal quantum yield of PSII (Fv/Fm) decreased significantly by severe drought stress. The significant decrease of effective quantum yield of PSII (Y(Ⅱ)) accompanied by the significant increase of quantum yield of regulated energy dissipation (Y(NPQ)) was observed under severe drought stress condition, but there was no change of quantum yield of nonregulated energy dissipation (Y(NO)). We detected that the coefficient of photochemical quenching (qP) decreased, and non-photochemical quenching (NPQ) increased significantly under severe drought stress. Furthermore, we found that maximum apparent electron transport rate (ETRmax) and saturating photosynthetically active radiation (PPFDsat) decreased significantly with drought stress aggravated. However, elevated [CO2] significantly increased FvlFm, qP and PPFDsat, and decreased NPQ under all water conditions, although there were no significant effects on chlorophyll content, Fo, Y(Ⅱ), Y(NPQ), Y(NO) and ETRmax. Therefore, it is concluded that CO2-fertilized greenhouses or elevated atmospheric [CO2] in the future could be favorable for cucumber growth and development, and beneficial to alleviate the negative effects of drought stresses to a certain extent.
文摘A novel and multi-disciplinary subject involving the relationships between changes in atmospheric CO<sub>2</sub> concentration throughout the geological history and features of plant anatomy is reviewed. Particular attention will be given to stomatal parameters (stomatal density and stomatal index) which are recorded at a cellular level in fossil plants and the relationships of these observable parameters to earth life history and global environmental change. Trends of atmospheric CO<sub>2</sub> concentrations during the Phanerozoic period are briefly introduced and recent conceptual advances in understanding the causal mechanisms for changes in stomatal parameters of land vascular plants are considered, In addition, some of the inherent problems and limitations of this kind of work are discussed and future research directions are presented.
基金Supported by National Basic Research Program of China(No.2006CB701401)National Natural Science Foundation of China(Nos.40502005,40772012,40802008)State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences)(Grant No.093110)
文摘Solenites vimineus (Phillips) Harris (Ginkgophyta) specimens with well-preserved cuticles were collected from five different beds in the oil shale member of the Middle Jurassic Yaojie Formation in the Yaojie Basin, Gansu Province, northwestern China. Gross morphology and fine structures of the fossil leaves were studied, and stomatal parameters were analyzed, according to which, the paleoatmospheric CO2 concentration can be deduced as 1512-1896 ppm that would have caused an increase in mean temperature of about 6.5-7.4℃. Carbon isotopes from the fossils indicate that the carbon isotopic discrimination and water use efficiency (WUE) of S. vimineus were raised nearly obtaining the ideal physiologic state in increased CO2 concentrations and temperature conditions, suggesting that S. vimineus records the paleoenvironmental information of the Middle Jurassic Yaojie Basin and can be used for environmental reconstruction.
基金Project supported by the National Natural Science Foundation of China (50272063)
文摘Eu3+ doped SiO2 nano-crystalline glasses were prepared by sol-gel method. The broad peak of XRD pattern indicates an amorphous SiO2 matrix. The affection of anneal time and anneal temperatures on photoluminescence (PL) properties of SiO2 glass under different Eu doping concentration were studied systematically. It is found that the optimized anneal time is about 3 h. The excitation spectra of 2% Eu3+ doped SiO2 glass powder were measured under various anneal temperatures, and the optimized anneal temperature is observed around 700℃. The fluorescence-quenching effect can be observed in the emission spectra when the annealing temperature exceeds 700℃. The emission spectra of different molar ratio dopants were measured at an annealed temperature of 500℃, and the concentration-quenching phenomenon has also been observed in SiO2 glass powder when the molar ratio of Eu3+ ion exceeds 3% . The result shows that the PL intensity approaches its maximum when the molar ratio of Eu3+ ions in the sample is about 3% . In addition, a comparatively stronger emission spectrum at wavelength of 703 nm which is corresponding to the energy transition 5D0→7F4 of Eu ions is also obtained.
文摘THE seasonal variance of soil CO<sub>2</sub> concentration with depth in soil profile was widely studied. Few similarresearches on this topic have been done in karst area which comprises 15% global terrestrial area. In thisnote, the research results about the seasonal and daily soil CO<sub>2</sub> concentration variance in karst area arereported. The soil gases were collected respectively by the sampling device at 200, 5,0, -5, -10,-15, -25, -35 and -45 cm from the land surface in meadow soil profile described by Zheng andlocated in the Hongfeng lake area in the central Guizhou Plateau which lies in the central East-Asia karstarea. Sampling time is in the morning, midday and at night in April, August and November, 1998 aswell as in January, 1999, respectively. Concentrations (volume percent) of CO<sub>2</sub> in soil gas samples
基金This work was supported by the National Key Basic Research and Development Project(Grant No.2002CB41250l)the National Natural Science Foundation of China(Grant Nos.90211006,30370257 and 30470280)the Knowledge Innovation Project of Institute of Geographical Sciences and Natural Resources Research,CAS(Grant No.CXIOG-E01-03-03).
文摘The Tibetan Plateau is characterized by lower atmospheric pressure, lower air temperature and high daily and seasonal variation due to high elevation. The photosynthesis of plants is significantly influenced by these alpine environmental factors. Apparent quantum yield (αA) is one of the basic parameters of photosynthesis and mass production. Its accuracy determination is of significance to model photosynthesis of C3 plants and global change on the plateau. In the Lhasa Plateau Ecological Station with 65.4 kPa of atmospheric pressure at an elevation of 3688 m, Li-Cor 6400 portable photosynthesis system was used to measure light response curves of winter wheat in different temperatures and intercellular CO2 concentration (Ci).The slope of light response curve in weak light area of PFD from 0 to 150 μmol m-2 S-1 was used to evaluate the value of αA. The dependence of αA on temperature and intercellular concentration was analyzed. In 30℃, the average value of αAWaS 0.0476 ± 0.0038. It is not quite different from the values in low elevation areas. αA is influenced both by temperature and by the ratio of CO2and O2 partial pressure ([CO2]/[O2]). The measured values in the previous study were much lower.This might be due to systematic errors from instrument and data processing methods. The values of αA decreased linearly with temperature. It decreased 0.0007 in every 1℃ increase of temperature. The decrease slope is similar to those of C3 plants in the previous researches. While [O2] is constant, αA increases with Ciwith a hyperbolic relationship. In comparison with low elevation areas, the αA on the Tibetan Plateau is more sensitive to increase of CO2.
基金supported by the National Natural Science Foundation of China (Nos. 40875041,40631006,40975038)
文摘Successive filtration and comparison show that the stratosphere air temperature in 10 hPa-layer of the Northern Hemisphere (NH) in July continuously increases,which is associated to the increases in greenhouse gases mostly CO2,volcanic activities,and solar activity,demonstrating the follows.(a) The increase in CO2 concentration is largely consistent with that of the stratosphere air temperature in 10 hPa-layer of the NH in July.However,the increase in the air temperature is not in a linear pattern,during which several cooling events interrupt.The cooling events between late 1960s and late 1970s are remarkable ones and so is the one before mid 1990s.Analysis shows that these events are induced by volcanic activities and solar activity.(b) The CO2-free variation in the stratosphere air temperature in 10 hPa-layer of the NH is consistent with that of the solar magnetic index.The wave crests and wave troughs of the two curves are consistent in phase,and the curve of solar magnetic index leads the other slightly.In other words,when the solar magnetic pole is southward,a warming in the NH stratosphere corresponds;and on the contrary,the northward solar magnetic pole corresponds to a cooling event.The variation in solar magnetic polarity strongly impacts the variation in the stratosphere temperature.