To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta(PRD)region,integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17,2014.The ...To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta(PRD)region,integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17,2014.The concentrations and chemical compositions of PM2.5,aerosol optical properties and meteorological parameters were measured.The mean value of PM2.5 increased from less than 35(excellent)to 35-75μg/m^3(good)and then to greater than 75μg/m^3(pollution),corresponding to mean PM2.5 values of 24.9,51.2,and 93.3μg/m^3,respectively.The aerosol scattering hygroscopic growth factor(f(RH=80%))values were 2.0,2.12,and 2.18 for the excellent,good,and pollution levels,respectively.The atmospheric extinction coefficient(σext)and the absorption coefficient of aerosols(σap)increased,and the single scattering albedo(SSA)decreased from the excellent to the pollution levels.For different air mass sources,under excellent and good levels,the land air mass from northern Heshan had lower f(RH)andσsp values.In addition,the mixed aerosol from the sea and coastal cities had lower f(RH)and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods.展开更多
The present study was conducted to evaluate the effects of partial root-zone drying （PRD） irrigation technique on stomatal conductance （gs）, leaf water potential （qJpd）, leaf relative water content （RWC）, vege...The present study was conducted to evaluate the effects of partial root-zone drying （PRD） irrigation technique on stomatal conductance （gs）, leaf water potential （qJpd）, leaf relative water content （RWC）, vegetative growth, fruit quality and enzymatic antioxidants of young plants of four Olea europaea L. varieties （Picholine Marocaine, Haouzia, Picholine Languedoc and Manzanilla） grown under arid conditions in Southern Morocco. In this irrigation strategy, a split-root technique was used to divide the root system of the plants in two parts. Two water regimes were used： （1） control, with both root compartments well watered; （2） PRD, with one compartment irrigated （50% of the control）, the other compartment was kept dry switching every 10 days. For all olive varieties studied, gs and the shoot length of the plants subjected to PRD decreased, whereas, Woo and RWC remained higher. The effect of PRD was similar among the four olive varieties, with their stomata closing in response to the water deficit before any significant changes in leaf water status were detectable. At the agronomic level, the benefits of PRD on olive were expressed by an earlier maturity and by higher values of olive fruit weight and dimensions, especially, in Manzanilla, which produced a fruit reaching 7.1 g and 2.6 cm, respectively. The enzymatic activities of soluble peroxidases （POX）, insoluble peroxidases （POXins）, polyphenoloxidase （PPO） and superoxide dismutase （SOD） were up-regulated under PRD. Picholine Marocaine and Haouzia showed higher enzymatic activities revealing that in these two varieties, PRD had possibly induced oxidative stress, which resulted in an up-regulation of the antioxidant activities of POXins, POX, PPO and SOD under water deficit.展开更多
基金supported by the National Natural Science Foundation of China(No.91544221)the People’s Republic of China Science and Technology Department(No.2016YFC0202004)
文摘To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta(PRD)region,integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17,2014.The concentrations and chemical compositions of PM2.5,aerosol optical properties and meteorological parameters were measured.The mean value of PM2.5 increased from less than 35(excellent)to 35-75μg/m^3(good)and then to greater than 75μg/m^3(pollution),corresponding to mean PM2.5 values of 24.9,51.2,and 93.3μg/m^3,respectively.The aerosol scattering hygroscopic growth factor(f(RH=80%))values were 2.0,2.12,and 2.18 for the excellent,good,and pollution levels,respectively.The atmospheric extinction coefficient(σext)and the absorption coefficient of aerosols(σap)increased,and the single scattering albedo(SSA)decreased from the excellent to the pollution levels.For different air mass sources,under excellent and good levels,the land air mass from northern Heshan had lower f(RH)andσsp values.In addition,the mixed aerosol from the sea and coastal cities had lower f(RH)and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods.
文摘The present study was conducted to evaluate the effects of partial root-zone drying （PRD） irrigation technique on stomatal conductance （gs）, leaf water potential （qJpd）, leaf relative water content （RWC）, vegetative growth, fruit quality and enzymatic antioxidants of young plants of four Olea europaea L. varieties （Picholine Marocaine, Haouzia, Picholine Languedoc and Manzanilla） grown under arid conditions in Southern Morocco. In this irrigation strategy, a split-root technique was used to divide the root system of the plants in two parts. Two water regimes were used： （1） control, with both root compartments well watered; （2） PRD, with one compartment irrigated （50% of the control）, the other compartment was kept dry switching every 10 days. For all olive varieties studied, gs and the shoot length of the plants subjected to PRD decreased, whereas, Woo and RWC remained higher. The effect of PRD was similar among the four olive varieties, with their stomata closing in response to the water deficit before any significant changes in leaf water status were detectable. At the agronomic level, the benefits of PRD on olive were expressed by an earlier maturity and by higher values of olive fruit weight and dimensions, especially, in Manzanilla, which produced a fruit reaching 7.1 g and 2.6 cm, respectively. The enzymatic activities of soluble peroxidases （POX）, insoluble peroxidases （POXins）, polyphenoloxidase （PPO） and superoxide dismutase （SOD） were up-regulated under PRD. Picholine Marocaine and Haouzia showed higher enzymatic activities revealing that in these two varieties, PRD had possibly induced oxidative stress, which resulted in an up-regulation of the antioxidant activities of POXins, POX, PPO and SOD under water deficit.
