Vertical flow constructed wetlands is a typical ecological sanitation system for sewage treatment. The removal rates for COD, BOD 5, SS, TN, and TP were 60%, 80%, 74%, 49% and 79%, respectively, when septic tank effl...Vertical flow constructed wetlands is a typical ecological sanitation system for sewage treatment. The removal rates for COD, BOD 5, SS, TN, and TP were 60%, 80%, 74%, 49% and 79%, respectively, when septic tank effluent was treated by vertical flow filter. So the concentration of COD and BOD\-5 in the treated effluent could meet the quality standard for irrigation water. After that the treated effluent was used for hydroponic cultivation of water spinach and romaine lettuce, the removal efficiencies of the whole system for COD, BOD\-5, SS, TN and TP were 71 4%, 97 5%, 96 9%, 86 3%, and 87 4%, respectively. And it could meet the integrated wastewater discharge standard for secondary biological treatment plant. It was found that using treated effluent for hydroponic cultivation of vegetables could reduce the nitrate content in vegetables. The removal rates for total bacteria and coliform index by using vertical flow bed system with cinder substrate were 80%—90% and 85%—96%, respectively.展开更多
By using the analysis method of game theory,this paper analyzes the phenomenon of price paradox of "vegetable basket" in China and its reason as follows:the price paradox of "vegetable basket" in C...By using the analysis method of game theory,this paper analyzes the phenomenon of price paradox of "vegetable basket" in China and its reason as follows:the price paradox of "vegetable basket" in China is that if the vegetable is cheap,it will harm farmers,and if the vegetable is expensive,it will harm people;high-cost logistics,low negotiation status of vegetable growers and cooperation predicament are responsible for price paradox.Based on the theoretical basis of strategic choice-theory of intermediaries,it indicates that the intermediaries can realize effective transaction and save transaction cost.The strategic choice of solving price paradox of "vegetable basket" is put forward as follows:support vegetable growers' cooperatives,reduce transaction cost and raise the negotiation status of vegetable growers;develop the model of connection of agricultural products and supermarkets,and reduce the cost of transport and distribution;innovate upon intermediaries and develop the third-party logistics.展开更多
Large-scale transportation infrastructure construction in ecologically vulnerable areas such as the karst region of Southwest China requires estimation method for better project design.This research was carried out on...Large-scale transportation infrastructure construction in ecologically vulnerable areas such as the karst region of Southwest China requires estimation method for better project design.This research was carried out on a four-lane highway(the Guilin-Guiyang highway,G76)and a two-lane highspeed railway(the Guilin-Guiyang high-speed railway,GGHSR)in karst areas in Guizhou and Guangxi provinces.The highway and high-speed railway were constructed in the 2010 s and covered by Landsat images whose multispectral information could be used for research purposes.In this study,the severity of the impact and the CO2 emissions from the G76 and GGHSR construction were evaluated.Landsat images and field meteorological measurements were applied to calculate the surface functional parameters(surface temperature and surface wetness)and heat fluxes(latent,sensible and ground heat flux)before and during the highway and high-speed railway construction;the amount of CO2 emissions during the G76 and GGHSR construction were determined by using budget sheets,which record the detail consumptions of materials and energy.The results showed that the decrease of water evaporation from the highway and high-speed railway construction can reach up to 26.4 m3 and 20.1 m3 per kilometer,which corresponds to an average decrease in the vegetation cooling effect of 18.0 MWh per day per highway kilometer and 13.7 MWh per day per high-speed railway kilometer,respectively.At the meantime,the average CO2 emission densities from the G76 and GGHSR construction can reach up to 24813.7 and 36921.1 t/km,respectively.This study implied that extensive line constructions have a significant impact on the local climate and the energy balance,and it is evident that selecting and planting appropriate plant species can compensate for the adverse effects of line constructions in karst mountain regions.展开更多
高陡岩石边坡生态修复是矿山生态修复领域中的重难点之一。通过中国期刊全文数据库和Web of Science核心合集数据库,对2003-2022年发表的关于高陡岩石边坡的文献进行检索与综述分析。本研究分析了高陡岩石边坡的年度发文量和研究热点,...高陡岩石边坡生态修复是矿山生态修复领域中的重难点之一。通过中国期刊全文数据库和Web of Science核心合集数据库,对2003-2022年发表的关于高陡岩石边坡的文献进行检索与综述分析。本研究分析了高陡岩石边坡的年度发文量和研究热点,从边坡稳定性、植生环境构造、植被配置等方面对高陡岩石边坡生态修复现状进行探讨,以期为今后该领域的研究提供参考方向。展开更多
[目的]把握生产建设项目废弃地植被恢复的发展历程及现阶段的研究热点问题,推进该研究领域的发展。[方法]以Web of Science数据库及CNKI数据库文献为基础,使用CiteSpace软件的文献计量方法对文献进行了分析。[结果](1)生产建设项目废弃...[目的]把握生产建设项目废弃地植被恢复的发展历程及现阶段的研究热点问题,推进该研究领域的发展。[方法]以Web of Science数据库及CNKI数据库文献为基础,使用CiteSpace软件的文献计量方法对文献进行了分析。[结果](1)生产建设项目废弃地植被恢复研究受到国内外研究者的共同关注,中国、印度和美国为主要发文国家。在国际上,印度科学与工业研究理事会(CSIR)和中国科学院是相关文章发表最多的机构,国内机构中发文量排名居榜首的是北京林业大学。(2)目前国际研究的知识群组主要分布在生态修复技术、生物多样性、生态恢复质量评价等方面。国内研究侧重于恢复生态系统结构、植被恢复模式和土壤质量评价体系等方面。(3)根据关键词突现分析,“生态系统服务”“植被恢复”“煤矿弃土”等是目前国际研究的热点;国内近年研究则聚焦于“生态恢复”“景观设计”“规划设计”等方面。[结论]目前的研究多为短期试验,鲜有针对大范围下整个恢复过程的研究,全面重建生态系统功能的研究尚不完善,未来的研究热点聚焦于在进行植被修复时考虑生态和景观综合效益,重视生态系统服务和景观设计。展开更多
文摘Vertical flow constructed wetlands is a typical ecological sanitation system for sewage treatment. The removal rates for COD, BOD 5, SS, TN, and TP were 60%, 80%, 74%, 49% and 79%, respectively, when septic tank effluent was treated by vertical flow filter. So the concentration of COD and BOD\-5 in the treated effluent could meet the quality standard for irrigation water. After that the treated effluent was used for hydroponic cultivation of water spinach and romaine lettuce, the removal efficiencies of the whole system for COD, BOD\-5, SS, TN and TP were 71 4%, 97 5%, 96 9%, 86 3%, and 87 4%, respectively. And it could meet the integrated wastewater discharge standard for secondary biological treatment plant. It was found that using treated effluent for hydroponic cultivation of vegetables could reduce the nitrate content in vegetables. The removal rates for total bacteria and coliform index by using vertical flow bed system with cinder substrate were 80%—90% and 85%—96%, respectively.
文摘By using the analysis method of game theory,this paper analyzes the phenomenon of price paradox of "vegetable basket" in China and its reason as follows:the price paradox of "vegetable basket" in China is that if the vegetable is cheap,it will harm farmers,and if the vegetable is expensive,it will harm people;high-cost logistics,low negotiation status of vegetable growers and cooperation predicament are responsible for price paradox.Based on the theoretical basis of strategic choice-theory of intermediaries,it indicates that the intermediaries can realize effective transaction and save transaction cost.The strategic choice of solving price paradox of "vegetable basket" is put forward as follows:support vegetable growers' cooperatives,reduce transaction cost and raise the negotiation status of vegetable growers;develop the model of connection of agricultural products and supermarkets,and reduce the cost of transport and distribution;innovate upon intermediaries and develop the third-party logistics.
基金funded by the Science and Technology Department of Guizhou Province (No. [2019]1427)Guizhou Provincial Forestry Department (No. [2017]15)National key research and development program of China (No.2016YFC0502605)
文摘Large-scale transportation infrastructure construction in ecologically vulnerable areas such as the karst region of Southwest China requires estimation method for better project design.This research was carried out on a four-lane highway(the Guilin-Guiyang highway,G76)and a two-lane highspeed railway(the Guilin-Guiyang high-speed railway,GGHSR)in karst areas in Guizhou and Guangxi provinces.The highway and high-speed railway were constructed in the 2010 s and covered by Landsat images whose multispectral information could be used for research purposes.In this study,the severity of the impact and the CO2 emissions from the G76 and GGHSR construction were evaluated.Landsat images and field meteorological measurements were applied to calculate the surface functional parameters(surface temperature and surface wetness)and heat fluxes(latent,sensible and ground heat flux)before and during the highway and high-speed railway construction;the amount of CO2 emissions during the G76 and GGHSR construction were determined by using budget sheets,which record the detail consumptions of materials and energy.The results showed that the decrease of water evaporation from the highway and high-speed railway construction can reach up to 26.4 m3 and 20.1 m3 per kilometer,which corresponds to an average decrease in the vegetation cooling effect of 18.0 MWh per day per highway kilometer and 13.7 MWh per day per high-speed railway kilometer,respectively.At the meantime,the average CO2 emission densities from the G76 and GGHSR construction can reach up to 24813.7 and 36921.1 t/km,respectively.This study implied that extensive line constructions have a significant impact on the local climate and the energy balance,and it is evident that selecting and planting appropriate plant species can compensate for the adverse effects of line constructions in karst mountain regions.
文摘高陡岩石边坡生态修复是矿山生态修复领域中的重难点之一。通过中国期刊全文数据库和Web of Science核心合集数据库,对2003-2022年发表的关于高陡岩石边坡的文献进行检索与综述分析。本研究分析了高陡岩石边坡的年度发文量和研究热点,从边坡稳定性、植生环境构造、植被配置等方面对高陡岩石边坡生态修复现状进行探讨,以期为今后该领域的研究提供参考方向。
文摘[目的]把握生产建设项目废弃地植被恢复的发展历程及现阶段的研究热点问题,推进该研究领域的发展。[方法]以Web of Science数据库及CNKI数据库文献为基础,使用CiteSpace软件的文献计量方法对文献进行了分析。[结果](1)生产建设项目废弃地植被恢复研究受到国内外研究者的共同关注,中国、印度和美国为主要发文国家。在国际上,印度科学与工业研究理事会(CSIR)和中国科学院是相关文章发表最多的机构,国内机构中发文量排名居榜首的是北京林业大学。(2)目前国际研究的知识群组主要分布在生态修复技术、生物多样性、生态恢复质量评价等方面。国内研究侧重于恢复生态系统结构、植被恢复模式和土壤质量评价体系等方面。(3)根据关键词突现分析,“生态系统服务”“植被恢复”“煤矿弃土”等是目前国际研究的热点;国内近年研究则聚焦于“生态恢复”“景观设计”“规划设计”等方面。[结论]目前的研究多为短期试验,鲜有针对大范围下整个恢复过程的研究,全面重建生态系统功能的研究尚不完善,未来的研究热点聚焦于在进行植被修复时考虑生态和景观综合效益,重视生态系统服务和景观设计。
