Some key factors on the heavy metals removal efficiencies were studied when soil washing technology was used in the remediation of soils contaminated by multiple heavy metals. The results show that the dissolubilities...Some key factors on the heavy metals removal efficiencies were studied when soil washing technology was used in the remediation of soils contaminated by multiple heavy metals. The results show that the dissolubilities of Cu and Zn are promoted by humic acids, but Pb and Cd are inhibited by humic acids; heavy metals in the clay are more difficult to be extracted than silt; the strong acidic soils can cause the protonation of EDTA and weaken its extracting ability; EDTA is effective for extracting Pb and Cd, while oxalate (OX) is effective for extracting Cu and Zn; and biosurfactant can be used as additive to improve the removal of some particular heavy metals.展开更多
Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, ...Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, this work estimates local-scale vehicular emissions and concentrations near a highway traffic network, where a school zone is located in. In the case study, VISSIM traffic micro-simulation is used to estimate the source of vehicular emissions at each roadway segment. The local-scale emission sources are then used as inputs to the California line source dispersion model(CALINE4) to estimate concentrations across the study area. To justify the local-scale emissions modeling approach, the simulation experiment is conducted under various traffic conditions. Different meteorological conditions are considered for emission dispersion. The work reveals that emission concentrations are usually higher at locations closer to the congested segments, freeway ramps and major arterial intersections. Compared to the macroscopic estimation(i.e. using network-average emission factors), the results show significantly different emission patterns when the local-scale emission modeling approach is used. In particular, it is found that the macroscopic approach over-estimates emission concentrations at freeways and under-estimations are observed at arterials and local streets. The results of the study can be used to compare to the US environmental protection agency(EPA) standards or any other air quality standard to further identify health risk in a fine-grained manner.展开更多
From the viewpoints of environmental conservation and energy efficiency,seawater-source heat pump system(SWHP) to provide district cooling and heating is applied in coastal areas.Based on the system,a heat transfer mo...From the viewpoints of environmental conservation and energy efficiency,seawater-source heat pump system(SWHP) to provide district cooling and heating is applied in coastal areas.Based on the system,a heat transfer model was established for cast heat exchanger(CHE) adopted by SWHP systems.The CHE consists of pipes immersed in the seawater and used for transferring heat between the seawater and the heat exchanger pipes of SWHP system.An experimental study was carried out to test the validity of the model.A program was developed in VB language and the effects of inlet temperature,flow rate of the secondary refrigerant and length of CHE on the results were investigated.The results of the numerical simulation are in consistence with the experiments in both winter and summer conditions.As a result,application of SWHP systems with CHE in coastal areas in China is feasible due to the favorable geographical conditions and environment.展开更多
In architecture and urban design,solar energy plays an important role to save fossil energy and preserve environment.Passive or active use of this energy needs especial consideration in the preliminary stage of design...In architecture and urban design,solar energy plays an important role to save fossil energy and preserve environment.Passive or active use of this energy needs especial consideration in the preliminary stage of design to the probable shadows.This work will answer two questions:1) How is it possible to distinguish shadow need periods during a year in a specific climate-2) How is it possible to produce shadow in hot periods without being deprived of pleasant sunshine in cold periods-In this regard,it will introduce the usage process and opportunities of "shading mask" of Olgyay as an easy and useful graphical method in six steps.At the end,different ways of using this method in design will be discussed.Several research projects that have been done in past 30 years will support the argument as examples of this method.展开更多
Large amount of groundwater discharging from tunnel is likely to cause destruction of the ecological environment in the vicinity of the tunnel, thus an appropriate drainage criterion should be established to balance t...Large amount of groundwater discharging from tunnel is likely to cause destruction of the ecological environment in the vicinity of the tunnel, thus an appropriate drainage criterion should be established to balance the tunnel construction and groundwater.To assess the related problems, an limiting drainage standard ranging from 0.5 to 2.0 m3/(m·d) was suggested for mountain tunnels based on survey and comparative analysis. After that, for the purpose of verifying the rationality of the standard, a calculated formula for dewatering funnel volume caused by drainage was deduced on the basis of the groundwater dynamics and experience method.Furthermore, the equation about the relationship between water discharge and drawdown of groundwater table was presented. The permeability coefficient, specific yield and groundwater table value were introduced, and then combined with the above equation, the drawdown of groundwater table under the proposed limiting drainage criterion was calculated. It is shown that the proposed drainage standard can reach the purpose of protecting ecological environment under the following two conditions. One is the permeability coefficient ranges from 10-4 to 10-5 m/s and the specific yield ranges from 0.1 to 0.001. The other is the permeability coefficient varies from 10-6 to 10-8 m/s and the specific yield varies from 0.1 to 0.01. In addition, a majority of common geotechnical layers are involved in the above ranges. Thus, the proposed limiting drainage standard which ranges from 0.5 to 2.0 m3/(m·d) for mountain tunnel is reasonable.展开更多
基金Project(20050532009) supported by the Doctoral Foundation of Ministry of Education of ChinaProjects(2006BAD03A1704, 2006BAD03A1706) supported by the National 11th-Five Technology Supporting Project
文摘Some key factors on the heavy metals removal efficiencies were studied when soil washing technology was used in the remediation of soils contaminated by multiple heavy metals. The results show that the dissolubilities of Cu and Zn are promoted by humic acids, but Pb and Cd are inhibited by humic acids; heavy metals in the clay are more difficult to be extracted than silt; the strong acidic soils can cause the protonation of EDTA and weaken its extracting ability; EDTA is effective for extracting Pb and Cd, while oxalate (OX) is effective for extracting Cu and Zn; and biosurfactant can be used as additive to improve the removal of some particular heavy metals.
文摘Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, this work estimates local-scale vehicular emissions and concentrations near a highway traffic network, where a school zone is located in. In the case study, VISSIM traffic micro-simulation is used to estimate the source of vehicular emissions at each roadway segment. The local-scale emission sources are then used as inputs to the California line source dispersion model(CALINE4) to estimate concentrations across the study area. To justify the local-scale emissions modeling approach, the simulation experiment is conducted under various traffic conditions. Different meteorological conditions are considered for emission dispersion. The work reveals that emission concentrations are usually higher at locations closer to the congested segments, freeway ramps and major arterial intersections. Compared to the macroscopic estimation(i.e. using network-average emission factors), the results show significantly different emission patterns when the local-scale emission modeling approach is used. In particular, it is found that the macroscopic approach over-estimates emission concentrations at freeways and under-estimations are observed at arterials and local streets. The results of the study can be used to compare to the US environmental protection agency(EPA) standards or any other air quality standard to further identify health risk in a fine-grained manner.
基金Project(2006BAJ04A15-03) supported by the National Science and Technology Pillar Program during the Eleventh Five-year Plan Period
文摘From the viewpoints of environmental conservation and energy efficiency,seawater-source heat pump system(SWHP) to provide district cooling and heating is applied in coastal areas.Based on the system,a heat transfer model was established for cast heat exchanger(CHE) adopted by SWHP systems.The CHE consists of pipes immersed in the seawater and used for transferring heat between the seawater and the heat exchanger pipes of SWHP system.An experimental study was carried out to test the validity of the model.A program was developed in VB language and the effects of inlet temperature,flow rate of the secondary refrigerant and length of CHE on the results were investigated.The results of the numerical simulation are in consistence with the experiments in both winter and summer conditions.As a result,application of SWHP systems with CHE in coastal areas in China is feasible due to the favorable geographical conditions and environment.
文摘In architecture and urban design,solar energy plays an important role to save fossil energy and preserve environment.Passive or active use of this energy needs especial consideration in the preliminary stage of design to the probable shadows.This work will answer two questions:1) How is it possible to distinguish shadow need periods during a year in a specific climate-2) How is it possible to produce shadow in hot periods without being deprived of pleasant sunshine in cold periods-In this regard,it will introduce the usage process and opportunities of "shading mask" of Olgyay as an easy and useful graphical method in six steps.At the end,different ways of using this method in design will be discussed.Several research projects that have been done in past 30 years will support the argument as examples of this method.
基金Projects(51078359,51208522,51208523)supported by the National Natural Science Foundation of ChinaProject(2010-122-009)supported by the Traffic Science and Technology Fund of Guizhou Province,ChinaProject(CX2011B098)supported by the Postgraduate Research Innovation Fund of Hunan Province,China
文摘Large amount of groundwater discharging from tunnel is likely to cause destruction of the ecological environment in the vicinity of the tunnel, thus an appropriate drainage criterion should be established to balance the tunnel construction and groundwater.To assess the related problems, an limiting drainage standard ranging from 0.5 to 2.0 m3/(m·d) was suggested for mountain tunnels based on survey and comparative analysis. After that, for the purpose of verifying the rationality of the standard, a calculated formula for dewatering funnel volume caused by drainage was deduced on the basis of the groundwater dynamics and experience method.Furthermore, the equation about the relationship between water discharge and drawdown of groundwater table was presented. The permeability coefficient, specific yield and groundwater table value were introduced, and then combined with the above equation, the drawdown of groundwater table under the proposed limiting drainage criterion was calculated. It is shown that the proposed drainage standard can reach the purpose of protecting ecological environment under the following two conditions. One is the permeability coefficient ranges from 10-4 to 10-5 m/s and the specific yield ranges from 0.1 to 0.001. The other is the permeability coefficient varies from 10-6 to 10-8 m/s and the specific yield varies from 0.1 to 0.01. In addition, a majority of common geotechnical layers are involved in the above ranges. Thus, the proposed limiting drainage standard which ranges from 0.5 to 2.0 m3/(m·d) for mountain tunnel is reasonable.
