A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and ...A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52μg m-2 under initial soil cadmium concentrations to 65μg m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.展开更多
Aiming at the issue that mass of gas emission from mining gob and the gas exceeded in working face, gob air leakage field and gas migration regularity in downlink ventilation was studied. In consideration of the influ...Aiming at the issue that mass of gas emission from mining gob and the gas exceeded in working face, gob air leakage field and gas migration regularity in downlink ventilation was studied. In consideration of the influence of natural wind pressure to analyze the stope face differential pressure, gob air leakage field distribution and gas migration regularity theoretically. Established a two-dimensional physical model with one source and one doab, and applied computational fluid dynamics analysis software Fluent to do numerical simulation, analyzed and contrasted to the areas of gob air leakage on size and gas emission from gob to working face on strength when using the downlink ventilation and uplink ventilation. When applied downward ventilation in stope face, the air leakage field of gob nearly working face, and the air leakage intensity were smaller than uplink, this can effectively reduce the gas emission from gob to working face; when used downlink ventilation, the air leakage airflow carry the lower amount of gas to doab than uplink ventilation, and more easily to mix the gas, reduced the possibility of gas accumulation in upper comer and the stratified flows, it can provide protection to mine with safe and effective production.展开更多
A gas migration controlling equation was formulated based on the characteristics of the dual pore–fracture media of coal mass and in consideration of the matrix exchange between pores and fractures.A model of permeab...A gas migration controlling equation was formulated based on the characteristics of the dual pore–fracture media of coal mass and in consideration of the matrix exchange between pores and fractures.A model of permeability dynamic evolution was established by analyzing the variation in effective stress during gas drainage and the action mechanism of the effect of coal matrix desorption on porosity and fracture in the coal body.A coupling model can then be obtained to characterize gas compressibility and coal deformability under the gas–solid coupling of loading coal.In addition,a 3D model of boreholes was established and solved for gas drainage based on the relevant physical parameters of real mines.The comparison and analysis results for the law of gas migration and the evolution of coal body permeability around the boreholes before and after gas extraction between the dual media and the single-seepage field models can provide a theoretical basis for further research on the action mechanism of gas drainage.展开更多
The northern Batinah occupies approximately 12,150 km2 in the north of Oman Quaternary deposits and Neogene＇s upper Fats form the aquifer units. MODFLOW compatible MT3D was used for simulation development of the area...The northern Batinah occupies approximately 12,150 km2 in the north of Oman Quaternary deposits and Neogene＇s upper Fats form the aquifer units. MODFLOW compatible MT3D was used for simulation development of the area. It can be concluded that： （1） The groundwater in the Batinah area generally flows from the south-west to the gulf of Oman in the north-east; （2） Recharge takes place through direct recharge from rainfall and wadi flow by about 902 ×10^3 ma/day; （3） The hydraulic conductivity attains a relatively wide range between 0.02 m/day and 78 m/day and 0.02 m/day and 60 m/day for the Quaternary and Fars respectively; （4） There is probably less potential for groundwater abstraction in the northern part of the area; （5） The water level decreased by about 6 m over 24 years and （6） The increase of salinity most likely due to a contribution of sea water intrusion from the gulf along the coast. It is recommended that： （1） automatic well control system should be installed to accurate measurements of abstraction; （2） further analysis under different future scenarios should be made and （3） formulate an integrated management plan for the basin.展开更多
基金Project supported by the Chinese Postdoctoral Foundation (No. 10129) and the Swedish Agricultural Science Research Foundation (N
文摘A model for simulating cadmium transport in a soil-plant system was built using a commercial simulating program named Powersim on the basis of input-output processes happening in the soil-plant system. Convective and dispersive transport processes of cadmium in soil profile are embedded. Simulations on a daily base have been done up to a total simulating time of 250 years. Results show that applications of sewage sludge and fertilizer at the simulated rates would only cause slight cadmium accumulations in each layer of the soil, and cadmium accumulation would be levelling off, reaching an equilibrium concentrations layer by layer downward after certain time. The time scale to reach an equilibrium concentration varies from 10 years for the top three layers to over 250 years for the bottom layers. Plant cadmium uptake would increase from 52μg m-2 under initial soil cadmium concentrations to 65μg m-2 under equilibrium soil cadmium concentrations, which would not exceed the maximum allowable cadmium concentration in wheat grains. Main parameters which influence cadmium accumulation and transport in soil are total cadmium input, rainfall, evaporation, plant uptake and soil properties.
文摘Aiming at the issue that mass of gas emission from mining gob and the gas exceeded in working face, gob air leakage field and gas migration regularity in downlink ventilation was studied. In consideration of the influence of natural wind pressure to analyze the stope face differential pressure, gob air leakage field distribution and gas migration regularity theoretically. Established a two-dimensional physical model with one source and one doab, and applied computational fluid dynamics analysis software Fluent to do numerical simulation, analyzed and contrasted to the areas of gob air leakage on size and gas emission from gob to working face on strength when using the downlink ventilation and uplink ventilation. When applied downward ventilation in stope face, the air leakage field of gob nearly working face, and the air leakage intensity were smaller than uplink, this can effectively reduce the gas emission from gob to working face; when used downlink ventilation, the air leakage airflow carry the lower amount of gas to doab than uplink ventilation, and more easily to mix the gas, reduced the possibility of gas accumulation in upper comer and the stratified flows, it can provide protection to mine with safe and effective production.
基金supported by Chinese Ministry of Education (No.213022A)the National Natural Science Foundation of China (No.51574112)+4 种基金Henan Key Laboratory of Biogenic Traces and Sedimentary Minerals (No.OTMP1410)the Key Research Project of Higher Education Institution of Henan Province in 2015 (No.15A440001)the Doctor Funds of Henan Polytechnic University (No.B2015-05)the Basic and Advanced Technology Research Projects of Henan Province (No.162300410031)the Science and Technology Innovation Funds for Distinguished Young Scholar in Henan Province (No.164100510013)
文摘A gas migration controlling equation was formulated based on the characteristics of the dual pore–fracture media of coal mass and in consideration of the matrix exchange between pores and fractures.A model of permeability dynamic evolution was established by analyzing the variation in effective stress during gas drainage and the action mechanism of the effect of coal matrix desorption on porosity and fracture in the coal body.A coupling model can then be obtained to characterize gas compressibility and coal deformability under the gas–solid coupling of loading coal.In addition,a 3D model of boreholes was established and solved for gas drainage based on the relevant physical parameters of real mines.The comparison and analysis results for the law of gas migration and the evolution of coal body permeability around the boreholes before and after gas extraction between the dual media and the single-seepage field models can provide a theoretical basis for further research on the action mechanism of gas drainage.
文摘The northern Batinah occupies approximately 12,150 km2 in the north of Oman Quaternary deposits and Neogene＇s upper Fats form the aquifer units. MODFLOW compatible MT3D was used for simulation development of the area. It can be concluded that： （1） The groundwater in the Batinah area generally flows from the south-west to the gulf of Oman in the north-east; （2） Recharge takes place through direct recharge from rainfall and wadi flow by about 902 ×10^3 ma/day; （3） The hydraulic conductivity attains a relatively wide range between 0.02 m/day and 78 m/day and 0.02 m/day and 60 m/day for the Quaternary and Fars respectively; （4） There is probably less potential for groundwater abstraction in the northern part of the area; （5） The water level decreased by about 6 m over 24 years and （6） The increase of salinity most likely due to a contribution of sea water intrusion from the gulf along the coast. It is recommended that： （1） automatic well control system should be installed to accurate measurements of abstraction; （2） further analysis under different future scenarios should be made and （3） formulate an integrated management plan for the basin.
