A water-conducting polyacrylamide/montmorillonite coating was prepared by solutionblending.The coating was coated on fiber and then composited with polymer to form a composite film material that used for water saving ...A water-conducting polyacrylamide/montmorillonite coating was prepared by solutionblending.The coating was coated on fiber and then composited with polymer to form a composite film material that used for water saving and tree planting in arid and desert regions.The coating＇s water-conducting characteristics and dynamic self-adjusting behavior were investigated by Fourier transform infrared（FTIR）spectroscopy,thermal analysis（TG-DTA）,and environmental scanning electron microscopy（ESEM）.The results showed that the coating＇s water-conducting rate increased but water-retention capacity weakened with increasing montmorillonite content.The water-loss rate was positively related to temperature and negatively related to soil moisture.Water potential greatly influenced the water-conducting rate of the coating during its water conduction process.When the coating was at a low water potential,the montmorillonite particles interconnected and water was conducted quickly via montmorillonite layers,whereas when the coating was at a high potential,the montmorillonite particles disconnected and water was conducted slowly via the swelled polyacrylamide net structure.The rate can be regulated by changing the proportion of polyacrylamide and montmorillonite to guarantee a reasonable water supply for trees and make trees easier to survive.Thus,the survival rate of trees can be increased and the use of water resources can be significantly reduced.展开更多
The aim of this paper is to offer a statistically sound method to make a precise account of the speed of land degradation and regeneration processes.Most common analyses of land degradation focus instead on the extent...The aim of this paper is to offer a statistically sound method to make a precise account of the speed of land degradation and regeneration processes.Most common analyses of land degradation focus instead on the extent of degraded areas,rather than on the intensity of degradation processes.The study was implemented for the Potential Extent of Desertification in China(PEDC),composed by arid,semi-arid,and dry sub-humid regions and refers to the period 2002 to 2012.The metrics were standard partial regression coefficients from stepwise regressions,fitted using Net Primary Productivity as the dependent variable,and year number and aridity as predictors.The results indicate that:①the extension of degrading lands(292896 km 2 or 9.12%of PEDC)overcomes the area that is recovering(194560 km 2 or 6.06%of PEDC);and②the intensity of degrading trends is lower than that of increasing trends in three land cover types(grassland,desert,and crops)and in two aridity levels(semi-arid and dry sub-humid).Such an outcome might pinpoint restoration policies by the Chinese government,and document a possible case of hysteresis.展开更多
基金Funded by the National Science Foundation of China(No.50772131)the National High-tech R&D Program of China(863Program)(No.2011AA322100)+1 种基金the Key Project of Chinese Ministry of Education(No.106086)the Fundmental Research Funds for the Central Universities(No.2010YJ05)
文摘A water-conducting polyacrylamide/montmorillonite coating was prepared by solutionblending.The coating was coated on fiber and then composited with polymer to form a composite film material that used for water saving and tree planting in arid and desert regions.The coating＇s water-conducting characteristics and dynamic self-adjusting behavior were investigated by Fourier transform infrared（FTIR）spectroscopy,thermal analysis（TG-DTA）,and environmental scanning electron microscopy（ESEM）.The results showed that the coating＇s water-conducting rate increased but water-retention capacity weakened with increasing montmorillonite content.The water-loss rate was positively related to temperature and negatively related to soil moisture.Water potential greatly influenced the water-conducting rate of the coating during its water conduction process.When the coating was at a low water potential,the montmorillonite particles interconnected and water was conducted quickly via montmorillonite layers,whereas when the coating was at a high potential,the montmorillonite particles disconnected and water was conducted slowly via the swelled polyacrylamide net structure.The rate can be regulated by changing the proportion of polyacrylamide and montmorillonite to guarantee a reasonable water supply for trees and make trees easier to survive.Thus,the survival rate of trees can be increased and the use of water resources can be significantly reduced.
基金European Space Agency(No.4000123342/18/I-NB)Science and Technology Service Network Initiative of Chinese Academy of Sciences(No.KFJ-STSZDTP-010-02)。
文摘The aim of this paper is to offer a statistically sound method to make a precise account of the speed of land degradation and regeneration processes.Most common analyses of land degradation focus instead on the extent of degraded areas,rather than on the intensity of degradation processes.The study was implemented for the Potential Extent of Desertification in China(PEDC),composed by arid,semi-arid,and dry sub-humid regions and refers to the period 2002 to 2012.The metrics were standard partial regression coefficients from stepwise regressions,fitted using Net Primary Productivity as the dependent variable,and year number and aridity as predictors.The results indicate that:①the extension of degrading lands(292896 km 2 or 9.12%of PEDC)overcomes the area that is recovering(194560 km 2 or 6.06%of PEDC);and②the intensity of degrading trends is lower than that of increasing trends in three land cover types(grassland,desert,and crops)and in two aridity levels(semi-arid and dry sub-humid).Such an outcome might pinpoint restoration policies by the Chinese government,and document a possible case of hysteresis.
