Measurements of three chlorofluorocarbons (CFCs): trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and trichlorotrifluoroethane (CFC-113), along with methyl chloroform (CH 3CCl 3) and carbon tetrachlo...Measurements of three chlorofluorocarbons (CFCs): trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and trichlorotrifluoroethane (CFC-113), along with methyl chloroform (CH 3CCl 3) and carbon tetrachloride (CCl 4) were made in water samples from Lake Washington, using Electron Capture-Gas Chromatography (EC-GC). The samples were collected in mid-autumn, a period when the lake’s upper layer undergoes rapid cooling. At the time of sampling, a strong vertical temperature gradient was present in the lake, with surface temperatures of ～14℃, and near bottom (50 meters) temperatures of ～8℃. The concentrations of dissolved CFC-12 and CFC-11 increased with depth, as expected from the higher solubilities of these gases at lower temperatures. Atmospheric measurements made at the sampling site at the time of the cruise, showed that CFC-11 and CFC-12 saturations in the near surface samples were 100 % and 106%, respectively. For the deepest sample (52 meters) CFC-11 and CFC-12 saturations were 102 % and 126 %. Because the surface layer of the lake responds to changes in atmospheric CFCs on a time scale of several weeks, the higher than equilibrium concentrations of CFC-12 observed at the time of sampling may reflect earlier episodes of elevated levels of atmospheric CFC-12 in this urban area. High concentrations of dissolved CFCs in runoff or industrial effluent might also lead to elevated CFC levels in the lake. The cold, deep water of Lake Washington is relatively isolated from the effects of surface gas exchange except during winter, and the supersaturations observed in the deep layer may reflect periods of elevated atmospheric CFC-12 levels from the previous winter season. These results were compared to summertime profiles of CFC-11 and CFC-12 made in 1994.展开更多
The urban developments have been carried out by only professionals for a long time because of efficiency and safety. However, most residents are ordinary people. Therefore, it is necessary to change the awareness of s...The urban developments have been carried out by only professionals for a long time because of efficiency and safety. However, most residents are ordinary people. Therefore, it is necessary to change the awareness of sustainable living environments, not only on the construction side but also the residents. In recent years, the number of cases of residents＇ participation in planning, maintaining, and repairing increased. However, sometimes youths and children, who might spend a lifetime longer than adults in a city after the developments have been done, are not included in this ＂Residents＂. Conceming youth and children＇s participation, CFC （child friendly city） is one of the good practices for sustainable development. It was launched by UNICEF （United Nations Intemational Children＇s Emergency Fund） and UN-Habitat in the Habitat II in 1996. City governments, especially in European countries, started to view CFC as their key concept for preservation and/or sustainable development. CFC means not only being ＂Children＂ friendly but also ＂All people＂ friendly. Various effects have been reported since the Historic Cities/districts included CFC in their city planning as a common concept, especially in education, community re-development, and operation and maintenance by the community. It is expected that better city planning in preservation and sustainable development can be achieved by adding CFC concept. In this research, an ideal way of city planning involving resident participation and the possibility in the future are analyzed based on case studies. Then a strategy of sustainable development and community planning involving youth and children＇s participation is proposed.展开更多
The world is experiencing global climate change, and most scientists attribute it to the accumulation in the atmosphere of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. Because of its enormous emiss...The world is experiencing global climate change, and most scientists attribute it to the accumulation in the atmosphere of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. Because of its enormous emission rate, carbon dioxide （CO2） is the main culprit. Almost all the anthropogenic CO2 emissions come from the burning of fossil fuels for electricity, heat, and transportation. Emissions of COg can be reduced by conservation, increased use of renewable energy sources, and increased efficiencies in both the production of electrical power and the transportation sector. Capture of CO2 can be accomplished with wet scrubbing, dry sorption, or biogenic fixation. After CO2 is captured, it must be transported either as a liquid or a supercritical fluid, which realistically can only be accomplished by pipeline or ship. Final disposal of CO2 will either be to underground reservoirs or to the ocean; at present, the underground option seems to be the only viable one. Various strategies and technologies involved with reduction of CO2 emissions and carbon capture and sequestration （CCS） are briefly reviewed in this paper.展开更多
An in-situ GC-ECD system was used to measure halocarbons at Shangdianzi （SDZ） GAW regional station. In this paper, we reported observational results of atmospheric CFC- 11 （CCI3F） mixing ratios from April 2007 to ...An in-situ GC-ECD system was used to measure halocarbons at Shangdianzi （SDZ） GAW regional station. In this paper, we reported observational results of atmospheric CFC- 11 （CCI3F） mixing ratios from April 2007 to March 2008. The CFC- 11 time series showed large variability. Approximately 62% observed values were filtered as non-background data. The median, 10% and 90% percentiles of CFC-11 background mixing ratios were 245.4 ppt （10-12 mol/mol）, 244.6 ppt and 246.1 ppt, respectively; whereas those of non-background CFC- 11 mixing ratios were 254.7, 246.6 and 272.1 ppt, respectively. Significant differences in background and non-background CFC-11 mixing ratios were observed between summer and autumn, mainly because of the CFC-11 stored in loam being prone to atmospheric release in hot seasons. Comparison of tile SDZ data with the five AGAGE stations suggested agreement with mid-high latitude Northern Hemisphere stations MHD, THD and RPB. The SDZ data were higher than that of Southern Hemisphere stations CGO and SMO. Higher CFC-11 mixing ratios measured in different seasons were always associated with winds from the W-WSW-SW sector, indicating that the airflow coming from this wind sector has a positive contribution to CFC- 11 concentrations. The CFC-11 mixing ratios were higher in autumn and summer than in spring and winter, in which its mixing ratios were very close to the atmospheric background level. This was happened especially when airflow originated from the NNE-NE-ENE-E sector, indicating the air masses coming from these wind directions was relatively clean.展开更多
文摘Measurements of three chlorofluorocarbons (CFCs): trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and trichlorotrifluoroethane (CFC-113), along with methyl chloroform (CH 3CCl 3) and carbon tetrachloride (CCl 4) were made in water samples from Lake Washington, using Electron Capture-Gas Chromatography (EC-GC). The samples were collected in mid-autumn, a period when the lake’s upper layer undergoes rapid cooling. At the time of sampling, a strong vertical temperature gradient was present in the lake, with surface temperatures of ～14℃, and near bottom (50 meters) temperatures of ～8℃. The concentrations of dissolved CFC-12 and CFC-11 increased with depth, as expected from the higher solubilities of these gases at lower temperatures. Atmospheric measurements made at the sampling site at the time of the cruise, showed that CFC-11 and CFC-12 saturations in the near surface samples were 100 % and 106%, respectively. For the deepest sample (52 meters) CFC-11 and CFC-12 saturations were 102 % and 126 %. Because the surface layer of the lake responds to changes in atmospheric CFCs on a time scale of several weeks, the higher than equilibrium concentrations of CFC-12 observed at the time of sampling may reflect earlier episodes of elevated levels of atmospheric CFC-12 in this urban area. High concentrations of dissolved CFCs in runoff or industrial effluent might also lead to elevated CFC levels in the lake. The cold, deep water of Lake Washington is relatively isolated from the effects of surface gas exchange except during winter, and the supersaturations observed in the deep layer may reflect periods of elevated atmospheric CFC-12 levels from the previous winter season. These results were compared to summertime profiles of CFC-11 and CFC-12 made in 1994.
文摘The urban developments have been carried out by only professionals for a long time because of efficiency and safety. However, most residents are ordinary people. Therefore, it is necessary to change the awareness of sustainable living environments, not only on the construction side but also the residents. In recent years, the number of cases of residents＇ participation in planning, maintaining, and repairing increased. However, sometimes youths and children, who might spend a lifetime longer than adults in a city after the developments have been done, are not included in this ＂Residents＂. Conceming youth and children＇s participation, CFC （child friendly city） is one of the good practices for sustainable development. It was launched by UNICEF （United Nations Intemational Children＇s Emergency Fund） and UN-Habitat in the Habitat II in 1996. City governments, especially in European countries, started to view CFC as their key concept for preservation and/or sustainable development. CFC means not only being ＂Children＂ friendly but also ＂All people＂ friendly. Various effects have been reported since the Historic Cities/districts included CFC in their city planning as a common concept, especially in education, community re-development, and operation and maintenance by the community. It is expected that better city planning in preservation and sustainable development can be achieved by adding CFC concept. In this research, an ideal way of city planning involving resident participation and the possibility in the future are analyzed based on case studies. Then a strategy of sustainable development and community planning involving youth and children＇s participation is proposed.
文摘The world is experiencing global climate change, and most scientists attribute it to the accumulation in the atmosphere of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. Because of its enormous emission rate, carbon dioxide （CO2） is the main culprit. Almost all the anthropogenic CO2 emissions come from the burning of fossil fuels for electricity, heat, and transportation. Emissions of COg can be reduced by conservation, increased use of renewable energy sources, and increased efficiencies in both the production of electrical power and the transportation sector. Capture of CO2 can be accomplished with wet scrubbing, dry sorption, or biogenic fixation. After CO2 is captured, it must be transported either as a liquid or a supercritical fluid, which realistically can only be accomplished by pipeline or ship. Final disposal of CO2 will either be to underground reservoirs or to the ocean; at present, the underground option seems to be the only viable one. Various strategies and technologies involved with reduction of CO2 emissions and carbon capture and sequestration （CCS） are briefly reviewed in this paper.
基金supported by Non-profit Research Project to Serve the Public Interest (Grant No. GYHY200806026)International S&T Cooperation Program of MOST (Grant No. 2007DFA20650)Research Fund for Returned Overseas Chinese Scholars of the State Education Ministry (Grant No. [2009]1108)
文摘An in-situ GC-ECD system was used to measure halocarbons at Shangdianzi （SDZ） GAW regional station. In this paper, we reported observational results of atmospheric CFC- 11 （CCI3F） mixing ratios from April 2007 to March 2008. The CFC- 11 time series showed large variability. Approximately 62% observed values were filtered as non-background data. The median, 10% and 90% percentiles of CFC-11 background mixing ratios were 245.4 ppt （10-12 mol/mol）, 244.6 ppt and 246.1 ppt, respectively; whereas those of non-background CFC- 11 mixing ratios were 254.7, 246.6 and 272.1 ppt, respectively. Significant differences in background and non-background CFC-11 mixing ratios were observed between summer and autumn, mainly because of the CFC-11 stored in loam being prone to atmospheric release in hot seasons. Comparison of tile SDZ data with the five AGAGE stations suggested agreement with mid-high latitude Northern Hemisphere stations MHD, THD and RPB. The SDZ data were higher than that of Southern Hemisphere stations CGO and SMO. Higher CFC-11 mixing ratios measured in different seasons were always associated with winds from the W-WSW-SW sector, indicating that the airflow coming from this wind sector has a positive contribution to CFC- 11 concentrations. The CFC-11 mixing ratios were higher in autumn and summer than in spring and winter, in which its mixing ratios were very close to the atmospheric background level. This was happened especially when airflow originated from the NNE-NE-ENE-E sector, indicating the air masses coming from these wind directions was relatively clean.
