Potted soybean plants were exposed to evaporate HTO for 1 h inside an exposure box at two different growth stage(flowering and podding stage, filling stage)during nighttime and daytime. The concentration of tissuefree...Potted soybean plants were exposed to evaporate HTO for 1 h inside an exposure box at two different growth stage(flowering and podding stage, filling stage)during nighttime and daytime. The concentration of tissuefree water tritium(TFWT) and organically bound tritium(OBT) in leaves and beans was measured at the end of the exposure. The results indicated that the quasi-equilibrium between the TFWT concentrations in the soybean leaves and the HTO concentration of the ambient air moisture required more than 1 h to be reached. The relative TFWT concentrations in the nighttime represent about 1/2 to 2/3of the concentrations obtained in the day in the leaves compared to about 1/2 to 4/3 in the beans. The relative OBT concentrations under night conditions were about 2/5 to 1/2 of those under day conditions in the leaves, contrary to 1/2–7/10 for the beans. By developing tritium concentration assessment model with a short-term release of atmospheric HTO, we comprehensively considered the plant growth stage and the environmental conditions.展开更多
Arctic nighttime land-surface temperatures derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the NASA Terra and Aqua satellites are investigated. We use the local equator crossing ti...Arctic nighttime land-surface temperatures derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the NASA Terra and Aqua satellites are investigated. We use the local equator crossing times of 22:30 and 01:30, respectively, in the analysis of changes, trends and variations on the Arctic region and within 120° sectors. We show increases in the number of days above 0°C and significant increase trends over their decadal periods of March 2000 through 2010 (MODIS Terra) and July 2002 through 2012 (MODIS Aqua). The MODIS Aqua nighttime Arctic land-surface temperature change, +0.2°C ± 0.2°C with P-value of 0.01 indicates a reduction relative to the MODIS Terra nighttime Arctic land-surface temperature change, +1.8°C ± 0.3°C with P-value of 0.01. This reduction is a decadal non-stationary component of the Arctic land-surface temperature changes. The reduction is greatest, -1.3°C ± 0.2°C with P-value of 0.01 in the Eastern Russia— Western North American sector of the Arctic during the July 2002 through 2012.展开更多
This study showed how the daytime length in Jiaozhou Bay affected the water temperature, which in turn affected the phytoplankton growth when solar radiation was sufficient for phytoplankton photosynthesis. Jiaozhou B...This study showed how the daytime length in Jiaozhou Bay affected the water temperature, which in turn affected the phytoplankton growth when solar radiation was sufficient for phytoplankton photosynthesis. Jiaozhou Bay observation data collected from May 1991 to February 1994 were used to analyze the daytime length vs water temperature relationship. Our study showed that daytime length and the variation controlled the cycle of water temperature flunctuation. Should the cyclic variation curve of the daytime length be moved back for two months it would be superimposed with temperature change. The values of daytime length and temperature that calculated in the dynamical model of daytime length lag vs water temperature were consistent with observed values. The light radiation and daytime length in this model determined the photochemistry process and the enzymic catalysis process of phytoplankton photosynthesis. In addition, by considering the effect of the daytime length on water temperature and photosynthesis, we could comprehend the joint effect of daytime length, water temperature, and nutrients, on the spatiotemporal variation of primary production in Jiaozhou Bay.展开更多
In order to provide theoretical basis and data support for improving the production mode of covering,this study investigated the nighttime air temperature formed by multiple layers of films with tunnel sheds and small...In order to provide theoretical basis and data support for improving the production mode of covering,this study investigated the nighttime air temperature formed by multiple layers of films with tunnel sheds and small tunnel sheds as trial subjects.The experiment was carried out in four tunnel sheds with 0 or 2 small tunnel sheds covered by 0,1,2 and 3 layers of films,respectively in Jinan,Shandong Province in winter of 2018.The nighttime air temperatures of tunnel sheds and small tunnel sheds formed by 1,2,3 and 4 layers of plastic film were measured and analyzed to simulate the temperature environment of early-spring season.The results showed that there were little differences between the nighttime air temperatures inside the tunnel sheds which was installed 0-3-layer small tunnel sheds inside,and there were uncertainty in the values of the air temperatures inside and outside the tunnel sheds;and the nighttime temperature conditions were constantly improved with the number of plastic film layers increasing under the conditions of this study.The analysis indicated that the mechanism of raising the temperature surrounded by plastic film was not only due to its own thermal parameter (thermal conductivity).MATLAB fitting analysis results showed that the increment of nighttime temperature in multi-film coverings became smaller with the number of film layers increasing.In this study,the number of layers in multi-film covering should not exceed 5 layers.展开更多
全球变暖具有明显的昼夜不对称性,温度升高影响冬小麦的生长发育,也改变了其冠层的光谱反射特性。为了研究昼夜不对称增温对冬小麦冠层反射光谱特性的影响,在南京采用开放式田间增温系统,开展昼夜不对称增温的人工控制试验,利用FieldSpe...全球变暖具有明显的昼夜不对称性,温度升高影响冬小麦的生长发育,也改变了其冠层的光谱反射特性。为了研究昼夜不对称增温对冬小麦冠层反射光谱特性的影响,在南京采用开放式田间增温系统,开展昼夜不对称增温的人工控制试验,利用FieldSpec Pro FR光谱仪测定了2个冬小麦品种扬麦15和徐麦31的冠层反射光谱,分析了冬小麦开花后冠层光谱反射率和一阶导数光谱,比较了2种增温方式对冠层反射光谱特性的影响。结果表明,与CK相比,昼夜不对称增温处理(白天增温1℃,夜间增温3℃,T2)的冬小麦冠层反射率,在近红外波段的下降最为显著,且以开花期的冬小麦冠层近红外波段反射率降低幅度最大。昼夜对称增温处理(白天增温2℃,夜间增温2℃,T1)下的冬小麦冠层反射率变化与T2处理后的变化相似,但其反射率降低幅度小于T2处理。在开花期,扬麦15在CK、T1、T2处理下近红外波段反射率分别为0.70、0.61、0.55,而徐麦31在CK、T1、T2处理下近红外波段反射率分别为0.65、0.60、0.52。由一阶导数光谱可以发现,T1、T2处理下,扬麦15红边位置由738 nm变为花后20 d的731和730 nm,俆麦31表现相同的规律。T1和T2处理也使得红边峰值下降,在开花期红边峰值下降幅度最大,且T2处理下降幅度较T1处理更大。与光谱反射率变化相对应,T1和T2均使2品种的叶绿素质量分数和叶面积指数(leaf area index,LAI)显著降低,以T2处理降低幅度最大。因此,昼夜不对称增温影响了冬小麦LAI、叶绿素质量分数、细胞结构和衰老程度,进而表现出冬小麦冠层反射光谱反射率的下降。展开更多
基金financially supported by the National Natural Science Foundation of China (No. 11575104)
文摘Potted soybean plants were exposed to evaporate HTO for 1 h inside an exposure box at two different growth stage(flowering and podding stage, filling stage)during nighttime and daytime. The concentration of tissuefree water tritium(TFWT) and organically bound tritium(OBT) in leaves and beans was measured at the end of the exposure. The results indicated that the quasi-equilibrium between the TFWT concentrations in the soybean leaves and the HTO concentration of the ambient air moisture required more than 1 h to be reached. The relative TFWT concentrations in the nighttime represent about 1/2 to 2/3of the concentrations obtained in the day in the leaves compared to about 1/2 to 4/3 in the beans. The relative OBT concentrations under night conditions were about 2/5 to 1/2 of those under day conditions in the leaves, contrary to 1/2–7/10 for the beans. By developing tritium concentration assessment model with a short-term release of atmospheric HTO, we comprehensively considered the plant growth stage and the environmental conditions.
文摘Arctic nighttime land-surface temperatures derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the NASA Terra and Aqua satellites are investigated. We use the local equator crossing times of 22:30 and 01:30, respectively, in the analysis of changes, trends and variations on the Arctic region and within 120° sectors. We show increases in the number of days above 0°C and significant increase trends over their decadal periods of March 2000 through 2010 (MODIS Terra) and July 2002 through 2012 (MODIS Aqua). The MODIS Aqua nighttime Arctic land-surface temperature change, +0.2°C ± 0.2°C with P-value of 0.01 indicates a reduction relative to the MODIS Terra nighttime Arctic land-surface temperature change, +1.8°C ± 0.3°C with P-value of 0.01. This reduction is a decadal non-stationary component of the Arctic land-surface temperature changes. The reduction is greatest, -1.3°C ± 0.2°C with P-value of 0.01 in the Eastern Russia— Western North American sector of the Arctic during the July 2002 through 2012.
文摘This study showed how the daytime length in Jiaozhou Bay affected the water temperature, which in turn affected the phytoplankton growth when solar radiation was sufficient for phytoplankton photosynthesis. Jiaozhou Bay observation data collected from May 1991 to February 1994 were used to analyze the daytime length vs water temperature relationship. Our study showed that daytime length and the variation controlled the cycle of water temperature flunctuation. Should the cyclic variation curve of the daytime length be moved back for two months it would be superimposed with temperature change. The values of daytime length and temperature that calculated in the dynamical model of daytime length lag vs water temperature were consistent with observed values. The light radiation and daytime length in this model determined the photochemistry process and the enzymic catalysis process of phytoplankton photosynthesis. In addition, by considering the effect of the daytime length on water temperature and photosynthesis, we could comprehend the joint effect of daytime length, water temperature, and nutrients, on the spatiotemporal variation of primary production in Jiaozhou Bay.
基金Supported by Weifang Comprehensive Experimental Station Project of National Watermelon and Melon Industrial Technology System(CARS-25)Agricultural Science and Technology Innovation Project of Shandong Academy of Agricultural Sciences(CXGC2018D05)
文摘In order to provide theoretical basis and data support for improving the production mode of covering,this study investigated the nighttime air temperature formed by multiple layers of films with tunnel sheds and small tunnel sheds as trial subjects.The experiment was carried out in four tunnel sheds with 0 or 2 small tunnel sheds covered by 0,1,2 and 3 layers of films,respectively in Jinan,Shandong Province in winter of 2018.The nighttime air temperatures of tunnel sheds and small tunnel sheds formed by 1,2,3 and 4 layers of plastic film were measured and analyzed to simulate the temperature environment of early-spring season.The results showed that there were little differences between the nighttime air temperatures inside the tunnel sheds which was installed 0-3-layer small tunnel sheds inside,and there were uncertainty in the values of the air temperatures inside and outside the tunnel sheds;and the nighttime temperature conditions were constantly improved with the number of plastic film layers increasing under the conditions of this study.The analysis indicated that the mechanism of raising the temperature surrounded by plastic film was not only due to its own thermal parameter (thermal conductivity).MATLAB fitting analysis results showed that the increment of nighttime temperature in multi-film coverings became smaller with the number of film layers increasing.In this study,the number of layers in multi-film covering should not exceed 5 layers.
文摘全球变暖具有明显的昼夜不对称性,温度升高影响冬小麦的生长发育,也改变了其冠层的光谱反射特性。为了研究昼夜不对称增温对冬小麦冠层反射光谱特性的影响,在南京采用开放式田间增温系统,开展昼夜不对称增温的人工控制试验,利用FieldSpec Pro FR光谱仪测定了2个冬小麦品种扬麦15和徐麦31的冠层反射光谱,分析了冬小麦开花后冠层光谱反射率和一阶导数光谱,比较了2种增温方式对冠层反射光谱特性的影响。结果表明,与CK相比,昼夜不对称增温处理(白天增温1℃,夜间增温3℃,T2)的冬小麦冠层反射率,在近红外波段的下降最为显著,且以开花期的冬小麦冠层近红外波段反射率降低幅度最大。昼夜对称增温处理(白天增温2℃,夜间增温2℃,T1)下的冬小麦冠层反射率变化与T2处理后的变化相似,但其反射率降低幅度小于T2处理。在开花期,扬麦15在CK、T1、T2处理下近红外波段反射率分别为0.70、0.61、0.55,而徐麦31在CK、T1、T2处理下近红外波段反射率分别为0.65、0.60、0.52。由一阶导数光谱可以发现,T1、T2处理下,扬麦15红边位置由738 nm变为花后20 d的731和730 nm,俆麦31表现相同的规律。T1和T2处理也使得红边峰值下降,在开花期红边峰值下降幅度最大,且T2处理下降幅度较T1处理更大。与光谱反射率变化相对应,T1和T2均使2品种的叶绿素质量分数和叶面积指数(leaf area index,LAI)显著降低,以T2处理降低幅度最大。因此,昼夜不对称增温影响了冬小麦LAI、叶绿素质量分数、细胞结构和衰老程度,进而表现出冬小麦冠层反射光谱反射率的下降。
