The cadmium （Cd） contents in rice plants and Cd accumulation in different parts of rice under Cd stress were studied to screen out Cd-highly tolerant and high-yield rice varieties. With different vadeties of japonic...The cadmium （Cd） contents in rice plants and Cd accumulation in different parts of rice under Cd stress were studied to screen out Cd-highly tolerant and high-yield rice varieties. With different vadeties of japonica and indica rice as the research objects, Cd contents and Cd accumulation of different rice varieties in harvest time were discussed by pot experiment, under two treatments of no adding Cd and Cd stress. Under both the two treatments, the Cd contents in different parts of rice all ranked as root〉stem〉leaf〉husk〉grain, and Cd was manly concentrated in dce roots. Cd accumulation and distribution differed among different rice varieties, especially among grains of different rice varieties. Among the 8 rice varieties, the increase of grain Cd content of Chunyou 84 was the smallest, indicating a weaker Cd accumulation ability. At the same time, the Cd accumulation in japonica rice was higher than that in indica rice under Cd stress. Under Cd stress, the yield of indica rice decreased significantly, while that of japonica rice increased. The lowest grain Cd content of Chunyou 84 indicated significant Cd tolerance. Although its yield was affected, it can still be recommended to be promoted in the Cd-polluted region of Hunan Province, considering the Cd security.展开更多
Dianchi Lake is one of the most eutrophic lakes in China. In order to understand this eutrophication and to help control the pollution, this research investigated the spatial distribution of Kjeldahl nitrogen (K-N) an...Dianchi Lake is one of the most eutrophic lakes in China. In order to understand this eutrophication and to help control the pollution, this research investigated the spatial distribution of Kjeldahl nitrogen (K-N) and total phosphorus(TP) through analysis of bottom water and sediment (3 depths) samples collected at 118 sites around Dianchi Lake. The concentrations of K-N and TP for the lake bottom water in the Caohai part of the lake were much higher than those in the Waihai part, generally decreasing from north to south. In the sediments, the K-N concentration was higher in the Caohai part and the middle of the Waihai part. On the other hand, TP in the sediments was greater in the southern and western parts. Both K-N and TP had similar spatial distributions for the sediment samples of three different depths.Vertically, the K-N and TP concentration in the sediments decreased with an increase in depth. This was evidence that eutrophication and pollution of Dianchi Lake was becoming gradually more severe. Exterior factors including uncontrolled input of domestic and industrial effluents as well as non-point pollution around the lake were the main reasons for serious eutrophication; therefore, controlling these was the first step in reducing eutrophication of Dianchi Lake.展开更多
Abstract： The Wenchuan earthquake generated strong surface disturbances and triggered a large number of loose deposits, resulting in the disaster- prone environment with special watershed hydrological characteristics...Abstract： The Wenchuan earthquake generated strong surface disturbances and triggered a large number of loose deposits, resulting in the disaster- prone environment with special watershed hydrological characteristics. This paper was to propose a debris flow formation process and explore the permeability characteristics and critical hydrodynamic conditions of the loose deposits triggered by the earthquake. The Guo Juanyan gully （31005＇27＂ N to 31005＇46＂ N, 103036＇58＂ E to 103037＇09＂ E） in Du Jiangyan City, located in the meizoseismal areas of the Wenchuan earthquake, was chosen as the study area and the disaster-prone environment was analyzed. The formation process of the debris flow was first proposed using a stability analysis, and then, the permeability characteristics of loose deposits were determined via in situ permeability experiments. Finally, the critical 1 h rainfall was simulated through a distributed hydrological model and verified by field observations. The formation process of debris flow could be divided into three stages based on the relationship between the hydrodynamic force and loose deposit resistance. The critical 1 h rainfall amounts under three antecedent moisture conditions （I-dry, Ⅱ-normal and Ⅲ-wet） were 52 mm/h, 43 mm/h and 34 mm/h, respectively. This study proposed a debris flow formation process in the meizoseismal areas of the Wenchuan earthquake based on the stability analysis and defined the rainfall threshold for debris flow early warning at the local level, which is significant for debris flow mitigation and risk management.展开更多
This study on the distribution features of petroleum hydrocarbon in water and sediment off the Fujian shore using data obtained from the baseline research on oceanic contamination in Fujian showed that: during the res...This study on the distribution features of petroleum hydrocarbon in water and sediment off the Fujian shore using data obtained from the baseline research on oceanic contamination in Fujian showed that: during the research period, petroleum hydrocarbon concentrations in water varied from 5.77 μg/L to 37.28 μg/L, averaged 14.48 μg/L; was lower in the wet season than in the dry season; and was highest in the Minjiang Estuary and Jiulong Estuary in both seasons. The petroleum hydrocarbon concentrations in shore sediment varied from 14.48 mg/kg to 784.36 mg/kg, averaged 133.3 mg/kg, and was closely related to sediment types (granularity).展开更多
Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0, 0.12,0.60 and 3.0 mmol L-1) and two levels of cadmium (0 and 4.0 pmol L--1) in greenhouse for a 18-day period.The concen...Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0, 0.12,0.60 and 3.0 mmol L-1) and two levels of cadmium (0 and 4.0 pmol L--1) in greenhouse for a 18-day period.The concentrations of phosphorus and cadmium in cell wall, cytoplasm and vacuoles of roots and leaveswere examined by cell fractionation techniques. With increasing phosphorus in medium, the contents of Pin cell wall, cytoplasm and vacuoles of corn and wheat roots and leaves increased. The highest content of Pwas observed in cell wall, next in vacuoles, and the lowest in cytoplasm. The wheat subcellular fractions inboth roots and leaves had higher concentrations of phosphorus than those of corn. Increasing phosphorus inmedium significantly inhibited the intracellular Cd accumulation in both species. However, at P concentrationup to 3.0 mmol L--1, the Cd content in cell wall was increased. Increasing phosphorus resulted in reductionof the subcellular Cd content in corn and wheat leaves. Compared with corn, the wheat roots had a higherCd content in the cell wall and vacuoles and a lower in cytoplasm, while in leaf subcellular fractions thewheat cell had a higher Cd content in its vacuoles and a lower one in its cytoplasm. The results indicate thatphosphorus may be involved in sequestration of Cd ionic activity in both cell wall and vacuoles by forminginsoluble Cd phosphate.展开更多
The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged ...The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation.The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain,rectangular channel with submerged vegetated corner,and two-stage rectangular channel with submerged vegetated floodplain,respectively.To predict the depth-averaged velocity with submerged vegetated floodplains,we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately.Moreover,further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results.The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction.The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable,which were more convenient than numerical simulations.The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels.Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes.展开更多
文摘The cadmium （Cd） contents in rice plants and Cd accumulation in different parts of rice under Cd stress were studied to screen out Cd-highly tolerant and high-yield rice varieties. With different vadeties of japonica and indica rice as the research objects, Cd contents and Cd accumulation of different rice varieties in harvest time were discussed by pot experiment, under two treatments of no adding Cd and Cd stress. Under both the two treatments, the Cd contents in different parts of rice all ranked as root〉stem〉leaf〉husk〉grain, and Cd was manly concentrated in dce roots. Cd accumulation and distribution differed among different rice varieties, especially among grains of different rice varieties. Among the 8 rice varieties, the increase of grain Cd content of Chunyou 84 was the smallest, indicating a weaker Cd accumulation ability. At the same time, the Cd accumulation in japonica rice was higher than that in indica rice under Cd stress. Under Cd stress, the yield of indica rice decreased significantly, while that of japonica rice increased. The lowest grain Cd content of Chunyou 84 indicated significant Cd tolerance. Although its yield was affected, it can still be recommended to be promoted in the Cd-polluted region of Hunan Province, considering the Cd security.
文摘Dianchi Lake is one of the most eutrophic lakes in China. In order to understand this eutrophication and to help control the pollution, this research investigated the spatial distribution of Kjeldahl nitrogen (K-N) and total phosphorus(TP) through analysis of bottom water and sediment (3 depths) samples collected at 118 sites around Dianchi Lake. The concentrations of K-N and TP for the lake bottom water in the Caohai part of the lake were much higher than those in the Waihai part, generally decreasing from north to south. In the sediments, the K-N concentration was higher in the Caohai part and the middle of the Waihai part. On the other hand, TP in the sediments was greater in the southern and western parts. Both K-N and TP had similar spatial distributions for the sediment samples of three different depths.Vertically, the K-N and TP concentration in the sediments decreased with an increase in depth. This was evidence that eutrophication and pollution of Dianchi Lake was becoming gradually more severe. Exterior factors including uncontrolled input of domestic and industrial effluents as well as non-point pollution around the lake were the main reasons for serious eutrophication; therefore, controlling these was the first step in reducing eutrophication of Dianchi Lake.
基金Financial support was provided by the international cooperation project of the Ministry of Science and Technology (Grant No.2013DFA21720)the Key Laboratory of Mountain Hazards and Earth Surface Processes independent project fundingthe National Natural Science Foundation (Grant No. 41372331)
文摘Abstract： The Wenchuan earthquake generated strong surface disturbances and triggered a large number of loose deposits, resulting in the disaster- prone environment with special watershed hydrological characteristics. This paper was to propose a debris flow formation process and explore the permeability characteristics and critical hydrodynamic conditions of the loose deposits triggered by the earthquake. The Guo Juanyan gully （31005＇27＂ N to 31005＇46＂ N, 103036＇58＂ E to 103037＇09＂ E） in Du Jiangyan City, located in the meizoseismal areas of the Wenchuan earthquake, was chosen as the study area and the disaster-prone environment was analyzed. The formation process of the debris flow was first proposed using a stability analysis, and then, the permeability characteristics of loose deposits were determined via in situ permeability experiments. Finally, the critical 1 h rainfall was simulated through a distributed hydrological model and verified by field observations. The formation process of debris flow could be divided into three stages based on the relationship between the hydrodynamic force and loose deposit resistance. The critical 1 h rainfall amounts under three antecedent moisture conditions （I-dry, Ⅱ-normal and Ⅲ-wet） were 52 mm/h, 43 mm/h and 34 mm/h, respectively. This study proposed a debris flow formation process in the meizoseismal areas of the Wenchuan earthquake based on the stability analysis and defined the rainfall threshold for debris flow early warning at the local level, which is significant for debris flow mitigation and risk management.
文摘This study on the distribution features of petroleum hydrocarbon in water and sediment off the Fujian shore using data obtained from the baseline research on oceanic contamination in Fujian showed that: during the research period, petroleum hydrocarbon concentrations in water varied from 5.77 μg/L to 37.28 μg/L, averaged 14.48 μg/L; was lower in the wet season than in the dry season; and was highest in the Minjiang Estuary and Jiulong Estuary in both seasons. The petroleum hydrocarbon concentrations in shore sediment varied from 14.48 mg/kg to 784.36 mg/kg, averaged 133.3 mg/kg, and was closely related to sediment types (granularity).
文摘Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0, 0.12,0.60 and 3.0 mmol L-1) and two levels of cadmium (0 and 4.0 pmol L--1) in greenhouse for a 18-day period.The concentrations of phosphorus and cadmium in cell wall, cytoplasm and vacuoles of roots and leaveswere examined by cell fractionation techniques. With increasing phosphorus in medium, the contents of Pin cell wall, cytoplasm and vacuoles of corn and wheat roots and leaves increased. The highest content of Pwas observed in cell wall, next in vacuoles, and the lowest in cytoplasm. The wheat subcellular fractions inboth roots and leaves had higher concentrations of phosphorus than those of corn. Increasing phosphorus inmedium significantly inhibited the intracellular Cd accumulation in both species. However, at P concentrationup to 3.0 mmol L--1, the Cd content in cell wall was increased. Increasing phosphorus resulted in reductionof the subcellular Cd content in corn and wheat leaves. Compared with corn, the wheat roots had a higherCd content in the cell wall and vacuoles and a lower in cytoplasm, while in leaf subcellular fractions thewheat cell had a higher Cd content in its vacuoles and a lower one in its cytoplasm. The results indicate thatphosphorus may be involved in sequestration of Cd ionic activity in both cell wall and vacuoles by forminginsoluble Cd phosphate.
基金Under the auspices of National Basic Research Program of China(No.2011CB403303)National Key Research and Development Program of China(No.2016YFC0402408-5)National Natural Science Foundation of China(No.51179181,40788001)
文摘The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation.The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain,rectangular channel with submerged vegetated corner,and two-stage rectangular channel with submerged vegetated floodplain,respectively.To predict the depth-averaged velocity with submerged vegetated floodplains,we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately.Moreover,further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results.The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction.The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable,which were more convenient than numerical simulations.The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels.Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes.
