The initiation mechanism of debris flow is regarded as the key step in understanding the debrisflow processes of occurrence, development and damage. Moreover, migration, accumulation and blocking effects of fine parti...The initiation mechanism of debris flow is regarded as the key step in understanding the debrisflow processes of occurrence, development and damage. Moreover, migration, accumulation and blocking effects of fine particles in soil will lead to soil failure and then develop into debris flow. Based on this hypothesis and considering the three factors of slope gradient, rainfall duration and rainfall intensity, 16 flume experiments were designed using the method of orthogonal design and completed in a laboratory. Particle composition changes in slope toe, volumetric water content, fine particle movement characteristics and soil failure mechanism were analyzed and understood as follows: the soil has complex, random and unstable structures, which causes remarkable pore characteristics of poor connectivity, non-uniformity and easy variation. The major factors that influence fine particle migration are rainfall intensity and slope. Rainfall intensity dominates particle movement, whereby high intensity rainfall induces a large number of mass movement and sharp fluctuation, causing more fine particles to accumulate at the steep slope toe. The slope toe plays an important role in water collection and fine particleaccumulation. Both fine particle migration and coarse particle movement appears similar fluctuation. Fine particle migration is interrupted in unconnected pores, causing pore blockage and fine particle accumulation, which then leads to the formation of a weak layer and further soil failure or collapses. Fine particle movement also causes debris flow formation in two ways: movement on the soil surface and migration inside the soil. The results verify the hypothesis that the function of fine particle migration in soil failure process is conducive for further understanding the formation mechanism of soil failure and debris flow initiation.展开更多
Selenium(Se)deficiency commonly occurs in soils of northeastern China and leads to insufficient Se intake by humans.A two-year field study of Se biofortification of common buckwheat supplied with 40 g Se ha^(-1)as sel...Selenium(Se)deficiency commonly occurs in soils of northeastern China and leads to insufficient Se intake by humans.A two-year field study of Se biofortification of common buckwheat supplied with 40 g Se ha^(-1)as selenite(Se(IV)),selenate(Se(VI)),or a combination(1/2 Se(IV+VI))was performed to investigate Se accumulation and translocation in plants and determine the effects of different forms of Se on the grain yield,biomass production,and Se use efficiency of plants and seeds.Se application increased seed Se concentrations to 47.1–265.1μg kg^(-1).Seed Se concentrations following Se(VI)or 1/2 Se(IV+VI)treatment exceeded 100μg kg^(-1),an amount suitable for crop Se biofortification.Se concentration in shoots and roots decreased with plant development,and Se translocation from root to shoot in Se(IV)-treated plants was lower than that in plants treated with 1/2 Se(IV+VI)and Se(VI).Both grain yield and biomass production increased under 1/2 Se(IV+VI)treatment,with grain yields reaching 1663.8 and 1558.5 kg ha^(-1)in 2015 and 2016,respectively,reflecting increases of 11.0% and 10.3% over those without Se application.The Se use efficiency of seeds and plants under Se(VI)treatment was significantly higher than those under 1/2 Se(IV+VI)and Se(IV)treatments.Thus,application of selenate could result in higher Se accumulation in buckwheat seeds than application of the other Se sources,but the combined application of selenate and selenite might be an alternative approach for improving buckwheat grain yield by Se biofortification in northeastern China.展开更多
The boron adsorption kinetic experiment in soil by means of a flow displacement technique showed that the kinetic data could be described with some mathematic equations. The average values of the correlation coefficie...The boron adsorption kinetic experiment in soil by means of a flow displacement technique showed that the kinetic data could be described with some mathematic equations. The average values of the correlation coefficient for zero-order, first-order, parabolic diffusion, Elovich, power function and exponential equations were 0.957, 0.982, 0.981, 0.984, 0.981 and 0.902, respectively. The correlation between adsorbed boron or its other expression form and time were the highest for first-order, parabolic diffusion, Elovich, and power function equations, the second for the zeroorder equation, and the lowest for the exponential equation. The parabolic diffusion equation fitted well the experimental results, with the least standard error among the six kinetic equations, showing that the movement of boron from soil solution to soil colloid surface may be controlled by boron diffusion speed. The boron content of rape seedling obtained from soil cultivation was correlated with the rate constants of the kinetic equations. The constants of first-order, parabolic diffusion,and exponential equations were significantly correlated with the boron content of the crop of NPK treatment at a 95% probability level, with correlation coefficients being 0.686, 0.691 and 0.641, respectively. In the case of zero-order equation, it was significant at 99% probability level (r =0.736). These results showed that the absorption kinetic constants of soil boron were closely related with the rape plant response to boron.展开更多
After the Tianjin Port 8.12 explosion, an enormous amount of potassium dichromate （K2Cr2O7） and butanone （CH3COCH2CH3） leaked into the coastal soil-groundwater system, which potentially threatened the environment ...After the Tianjin Port 8.12 explosion, an enormous amount of potassium dichromate （K2Cr2O7） and butanone （CH3COCH2CH3） leaked into the coastal soil-groundwater system, which potentially threatened the environment and human health. Determining the transport process of hazards is necessary to establish guidelines for remediating the contaminated area. This work aims to investigate the migration of potassium dichromate and butanone in the coastal soil-groundwater system through a coupling unsaturated-saturated numerical model, incorporating the HYDRUS model into the MODFLOW/ MT3D model. In the unsaturated zone, two-dimensional HYDRUS model was applied, and its recharge flux at the bottom boundary was utilized as the input of MODFLOW/MT3D model in the saturated zone. Results showed that Cr2O^（2-）7 migrated much faster than butanone in the unsaturated zone and reached the water table in about 1 year. In comparison, butanone was unlikely to enter the aquifer even 5 years later with a migration depth of about 2.2 m. Driven by groundwater, the Cr2O^（2-）7 that entered the aquifer migrated about 161 m toward southeast 5 years later. In the saturated zone, the contamination plume covered mainly the southeast area due to the groundwater flow direction.展开更多
The radiative transfer is one of the significant theories that describe the processes of scattering, emission, and absorption of electromagnetic radiant intensity through scattering medium. It is the basis of the stud...The radiative transfer is one of the significant theories that describe the processes of scattering, emission, and absorption of electromagnetic radiant intensity through scattering medium. It is the basis of the study on the quan-titative remote sensing. In this paper, the radiative characteristics of soil, vegetation, and atmosphere were described respectively. The numerical solution of radiative transfer was accomplished by Successive Orders of Scattering (SOS). A radiative transfer model for simulating microwave brightness temperature over land surfaces was constructed, de-signed, and implemented. Analyzing the database generated from soil-vegetation-atmosphere radiative transfer model under Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) configuration showed that the atmospheric effects on microwave brightness temperature should not be neglected, particularly for higher frequency, and can be parameterized. At the same time, the relationship between the emissivities of the different channels was developed. The study results will promote the development of algorithm to retrieve geophysical parameters from mi-crowave remotely sensed data.展开更多
Solid state 13C nuclear magnetic resonance （NMR） spectroscopy is a common tool to study the structure of soil humic fractions; however, knowledge regarding carbon structural relationships in humic fractions is limit...Solid state 13C nuclear magnetic resonance （NMR） spectroscopy is a common tool to study the structure of soil humic fractions; however, knowledge regarding carbon structural relationships in humic fractions is limited. In this study, mobile humic acid （MHA） and recalcitrant calcium humate （CallA） fractions were extracted from eight soils collected from six US states and representing a variety of soils and ecoregions, characterized by this spectroscopic technique and analyzed for statistical significance at P 〈 0.05. We found that the abundances of COO and N-C=O functional groups in the MHA fractions were negatively correlated to soil sand content, but were positively correlated to silt, total N and soil organic carbon contents. In contrast, the abundances of the COO and N-C=O functional groups were only positively correlated to the content of clay in the CallA fractions, indicating that the two humic fractions were associated with different soil components. The two 13C NMR peaks representing alkyls and OCH3/NCH were negatively correlated to the peaks representing aromatics, aromatic C-O and N-C=O/COO. Comparison of the sets of data from 13C NMR spectroscopy and ultrahigh resolution mass spectrometry revealed that the aromatic components identified by the two methods were highly consistent. The comparison further revealed that protein in MHA was associated with, or bound to, the nonpolar alkyl groups, but a component competitively against （or complementary to） aromatic groups in the MHA composition. These observations provided insight on the internal correlations of the functional groups of soil humic fractions.展开更多
Arsenic （As） contamination has become the environment issue of global concern. In China, large area of farmland and the site soil were contaminated by As, which means that suitable remedying methods were urgently ne...Arsenic （As） contamination has become the environment issue of global concern. In China, large area of farmland and the site soil were contaminated by As, which means that suitable remedying methods were urgently needed. Phytoremediation, as one of environment-friendly soil remediation techniques developed in recent years, shows a bright future for the remediation of As contaminated soils. However, phytoremediation efficiency needs to be enhanced further because of low concentration of bio- available As in the soils. A triangle flask culture experiment was carried out to study the effects of functional species, isolated from As-polluted soils, that could improve As mobility from the soil. These species included two bacilli, B 1 and B2 （Breviba- cillus） and two fungi, F1 （Trichoderma）, F2 （Fusarium）. They could transform the concentration of As fractionation in the soil sterilized by the method of 6~Co-T ray. Through the experiment, the concentrations of non-specifically-sorbed and specifical- ly-sorbed As fractionation, and pH value of culture solution with inoculated treatment were higher than that with the control. Especially, the concentration of non-specifically-sorbed As fractionation in the treatment-inoculated species was 2 to 6 times higher than that of non-inoculation treatment. Moreover, two bacilli and two fungi could produce IAA, which was conducive to the plant survival when they were jointly used in remedying the As-contaminated soil.展开更多
基金supported by the key international collaborative project of Natural Science Foundation of China(No.41520104002)
文摘The initiation mechanism of debris flow is regarded as the key step in understanding the debrisflow processes of occurrence, development and damage. Moreover, migration, accumulation and blocking effects of fine particles in soil will lead to soil failure and then develop into debris flow. Based on this hypothesis and considering the three factors of slope gradient, rainfall duration and rainfall intensity, 16 flume experiments were designed using the method of orthogonal design and completed in a laboratory. Particle composition changes in slope toe, volumetric water content, fine particle movement characteristics and soil failure mechanism were analyzed and understood as follows: the soil has complex, random and unstable structures, which causes remarkable pore characteristics of poor connectivity, non-uniformity and easy variation. The major factors that influence fine particle migration are rainfall intensity and slope. Rainfall intensity dominates particle movement, whereby high intensity rainfall induces a large number of mass movement and sharp fluctuation, causing more fine particles to accumulate at the steep slope toe. The slope toe plays an important role in water collection and fine particleaccumulation. Both fine particle migration and coarse particle movement appears similar fluctuation. Fine particle migration is interrupted in unconnected pores, causing pore blockage and fine particle accumulation, which then leads to the formation of a weak layer and further soil failure or collapses. Fine particle movement also causes debris flow formation in two ways: movement on the soil surface and migration inside the soil. The results verify the hypothesis that the function of fine particle migration in soil failure process is conducive for further understanding the formation mechanism of soil failure and debris flow initiation.
基金provided by the China Agriculture Research System(CARS-08-B-1)by Special Fund for Agro-scientific Research in the Public Interest(201503121-11)the China Scholarship Council for providing a graduate research fellowship to Y.Jiang as a joint Ph.D.student at Colorado State University for one year(201606350049)
文摘Selenium(Se)deficiency commonly occurs in soils of northeastern China and leads to insufficient Se intake by humans.A two-year field study of Se biofortification of common buckwheat supplied with 40 g Se ha^(-1)as selenite(Se(IV)),selenate(Se(VI)),or a combination(1/2 Se(IV+VI))was performed to investigate Se accumulation and translocation in plants and determine the effects of different forms of Se on the grain yield,biomass production,and Se use efficiency of plants and seeds.Se application increased seed Se concentrations to 47.1–265.1μg kg^(-1).Seed Se concentrations following Se(VI)or 1/2 Se(IV+VI)treatment exceeded 100μg kg^(-1),an amount suitable for crop Se biofortification.Se concentration in shoots and roots decreased with plant development,and Se translocation from root to shoot in Se(IV)-treated plants was lower than that in plants treated with 1/2 Se(IV+VI)and Se(VI).Both grain yield and biomass production increased under 1/2 Se(IV+VI)treatment,with grain yields reaching 1663.8 and 1558.5 kg ha^(-1)in 2015 and 2016,respectively,reflecting increases of 11.0% and 10.3% over those without Se application.The Se use efficiency of seeds and plants under Se(VI)treatment was significantly higher than those under 1/2 Se(IV+VI)and Se(IV)treatments.Thus,application of selenate could result in higher Se accumulation in buckwheat seeds than application of the other Se sources,but the combined application of selenate and selenite might be an alternative approach for improving buckwheat grain yield by Se biofortification in northeastern China.
文摘The boron adsorption kinetic experiment in soil by means of a flow displacement technique showed that the kinetic data could be described with some mathematic equations. The average values of the correlation coefficient for zero-order, first-order, parabolic diffusion, Elovich, power function and exponential equations were 0.957, 0.982, 0.981, 0.984, 0.981 and 0.902, respectively. The correlation between adsorbed boron or its other expression form and time were the highest for first-order, parabolic diffusion, Elovich, and power function equations, the second for the zeroorder equation, and the lowest for the exponential equation. The parabolic diffusion equation fitted well the experimental results, with the least standard error among the six kinetic equations, showing that the movement of boron from soil solution to soil colloid surface may be controlled by boron diffusion speed. The boron content of rape seedling obtained from soil cultivation was correlated with the rate constants of the kinetic equations. The constants of first-order, parabolic diffusion,and exponential equations were significantly correlated with the boron content of the crop of NPK treatment at a 95% probability level, with correlation coefficients being 0.686, 0.691 and 0.641, respectively. In the case of zero-order equation, it was significant at 99% probability level (r =0.736). These results showed that the absorption kinetic constants of soil boron were closely related with the rape plant response to boron.
基金supported by the National Natural Science Foundation of China(No.21656001)
文摘After the Tianjin Port 8.12 explosion, an enormous amount of potassium dichromate （K2Cr2O7） and butanone （CH3COCH2CH3） leaked into the coastal soil-groundwater system, which potentially threatened the environment and human health. Determining the transport process of hazards is necessary to establish guidelines for remediating the contaminated area. This work aims to investigate the migration of potassium dichromate and butanone in the coastal soil-groundwater system through a coupling unsaturated-saturated numerical model, incorporating the HYDRUS model into the MODFLOW/ MT3D model. In the unsaturated zone, two-dimensional HYDRUS model was applied, and its recharge flux at the bottom boundary was utilized as the input of MODFLOW/MT3D model in the saturated zone. Results showed that Cr2O^（2-）7 migrated much faster than butanone in the unsaturated zone and reached the water table in about 1 year. In comparison, butanone was unlikely to enter the aquifer even 5 years later with a migration depth of about 2.2 m. Driven by groundwater, the Cr2O^（2-）7 that entered the aquifer migrated about 161 m toward southeast 5 years later. In the saturated zone, the contamination plume covered mainly the southeast area due to the groundwater flow direction.
基金Under the auspices of National Natural Science Foundation of China (No. 40425012)"Hundred Talent" Program of Chinese Academy of Sciences
文摘The radiative transfer is one of the significant theories that describe the processes of scattering, emission, and absorption of electromagnetic radiant intensity through scattering medium. It is the basis of the study on the quan-titative remote sensing. In this paper, the radiative characteristics of soil, vegetation, and atmosphere were described respectively. The numerical solution of radiative transfer was accomplished by Successive Orders of Scattering (SOS). A radiative transfer model for simulating microwave brightness temperature over land surfaces was constructed, de-signed, and implemented. Analyzing the database generated from soil-vegetation-atmosphere radiative transfer model under Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) configuration showed that the atmospheric effects on microwave brightness temperature should not be neglected, particularly for higher frequency, and can be parameterized. At the same time, the relationship between the emissivities of the different channels was developed. The study results will promote the development of algorithm to retrieve geophysical parameters from mi-crowave remotely sensed data.
文摘Solid state 13C nuclear magnetic resonance （NMR） spectroscopy is a common tool to study the structure of soil humic fractions; however, knowledge regarding carbon structural relationships in humic fractions is limited. In this study, mobile humic acid （MHA） and recalcitrant calcium humate （CallA） fractions were extracted from eight soils collected from six US states and representing a variety of soils and ecoregions, characterized by this spectroscopic technique and analyzed for statistical significance at P 〈 0.05. We found that the abundances of COO and N-C=O functional groups in the MHA fractions were negatively correlated to soil sand content, but were positively correlated to silt, total N and soil organic carbon contents. In contrast, the abundances of the COO and N-C=O functional groups were only positively correlated to the content of clay in the CallA fractions, indicating that the two humic fractions were associated with different soil components. The two 13C NMR peaks representing alkyls and OCH3/NCH were negatively correlated to the peaks representing aromatics, aromatic C-O and N-C=O/COO. Comparison of the sets of data from 13C NMR spectroscopy and ultrahigh resolution mass spectrometry revealed that the aromatic components identified by the two methods were highly consistent. The comparison further revealed that protein in MHA was associated with, or bound to, the nonpolar alkyl groups, but a component competitively against （or complementary to） aromatic groups in the MHA composition. These observations provided insight on the internal correlations of the functional groups of soil humic fractions.
基金supported by the National Natural Science Foundation of China (Grant Nos. 21307080 and 41101232)Shanghai Knowledge Service Platform (Grant No. ZF1224)Key Discipline Construction Projects of Shanghai Second Polytechnic University (Grant No. XXKYS1404)
文摘Arsenic （As） contamination has become the environment issue of global concern. In China, large area of farmland and the site soil were contaminated by As, which means that suitable remedying methods were urgently needed. Phytoremediation, as one of environment-friendly soil remediation techniques developed in recent years, shows a bright future for the remediation of As contaminated soils. However, phytoremediation efficiency needs to be enhanced further because of low concentration of bio- available As in the soils. A triangle flask culture experiment was carried out to study the effects of functional species, isolated from As-polluted soils, that could improve As mobility from the soil. These species included two bacilli, B 1 and B2 （Breviba- cillus） and two fungi, F1 （Trichoderma）, F2 （Fusarium）. They could transform the concentration of As fractionation in the soil sterilized by the method of 6~Co-T ray. Through the experiment, the concentrations of non-specifically-sorbed and specifical- ly-sorbed As fractionation, and pH value of culture solution with inoculated treatment were higher than that with the control. Especially, the concentration of non-specifically-sorbed As fractionation in the treatment-inoculated species was 2 to 6 times higher than that of non-inoculation treatment. Moreover, two bacilli and two fungi could produce IAA, which was conducive to the plant survival when they were jointly used in remedying the As-contaminated soil.
