Nutrient retention capacity by the land/water ecotone soil of Lake Baiyangdian was studied by means of simulation in situ. The results from column experiments suggested that the standard capacity for phosphorus adsorp...Nutrient retention capacity by the land/water ecotone soil of Lake Baiyangdian was studied by means of simulation in situ. The results from column experiments suggested that the standard capacity for phosphorus adsorption be less than P14 mg·kg -1 soil in order to meet the lake water quality regulation (P 0.1 mg·L -1 ). Thus the 9,333 hectares of ecotone around the lake could retain 1,245 tons phosphorus in the upper 50-cm soil without degrading the water quality. The amount was nearly 24 times large as that of taken by annual reed harvesting. The maximum capacity for phosphorus was measured as P 774 mg·kg -1 soil. The isothermal equation of phosphorus was also obtained. It was found that temperature had a significant effect on the transformation of nitrogen, and higher temperature would accelerated the nitrification rate. Nitrogen retention was conducted by the microbial activities in the soil and the uptake through aquatic vegetation. The research will benefit for better utilization of local ecotone and design of the planning project which aims to water eutrophication control.展开更多
Biochar, as a kind of soil amendment, has important effects on soil water retention. In this research, 4 different kinds of biochars were used to investigate their influences on hydraulic properties and water evaporat...Biochar, as a kind of soil amendment, has important effects on soil water retention. In this research, 4 different kinds of biochars were used to investigate their influences on hydraulic properties and water evaporation in a sandy soil from Hebei Province, China. Biochar had strong absorption ability in the sandy soil. The ratio of water content in the biochar to that in the sandy soil was less than the corresponding ratio of porosity. Because of the different hydraulic properties between the sandy soil and the biochar, the saturated hydraulic conductivity of the sandy soil gradually decreased with the increasing biochar addition. The biochar with larger pore volume and average pore diameter had better water retention. More water was retained in the sandy soil when the biochar was added in a single layer, but not when the biochar was uniformly mixed with soil. Particle size of the added biochar had a significant influence on the hydraulic properties of the mixture of sand and biochar. Grinding the biochar into powder destroyed the pore structure, which simultaneously reduced the water absorption ability and hydraulic conductivity of the biochar. For this reason, adding biochar powder to the sandy soil would not decrease the water evaporation loss of the soil itself.展开更多
The bentonite barrier of underground repositories for high-level radioactive waste will be hydrated by the groundwater while it is subjected to high temperatures due to the radioactive decay of the wastes. These chang...The bentonite barrier of underground repositories for high-level radioactive waste will be hydrated by the groundwater while it is subjected to high temperatures due to the radioactive decay of the wastes. These changes of temperature affect the hydraulic and mechanical responses of bentonite, which has important effects on design and performance of repositories. The temperature influence on the hydro-mechanical behaviour of bentonite was studied in this paper by experiments, which were carried out with the Spanish FEBEX bentonite compacted at dry densities expected in the＇ repository （from 1.5 to 1.8 Mg/m^3）. The dependence of the swelling strains of bentonite on the temperature has been measured from 30℃ to 90 ℃. At high temperatures the swelling capacity of clay slightly decreases. Also, a clear decrease of swelling pressure as a function of temperature was observed for the same dry densities. Nevertheless, the deformation of bentonite is more dependent on the stress than the temperature. An increase in the permeability of water saturated bentonite with temperature has also been detected. The water retention curves of bentonite compacted at different dry densities were determined under isochoric conditions and in the range of temperatures from 20 ℃ to 120℃. For a given density and water content, the suction decreases as the temperature increases at a rate, which is larger than the one predicted on the basis of water surface tension changing with temperature. Mechanisms related to the physico-chemical interactions that take place at microscopic level, in particular the transfer of interlayer water to the macropores triggered by temperature, seem to explain qualitatively the experimental observations.展开更多
为改善大豆蛋白的功能性质,利用中性蛋白酶和胰蛋白酶对大豆浓缩蛋白、分离蛋白进行限制性酶解处理,并考察相应产品的酶解修饰模式与溶解性、保水性变化的关系。以酶解修饰蛋白质产品的氮溶解指数、保水率、单分子层水含量为指标,测定...为改善大豆蛋白的功能性质,利用中性蛋白酶和胰蛋白酶对大豆浓缩蛋白、分离蛋白进行限制性酶解处理,并考察相应产品的酶解修饰模式与溶解性、保水性变化的关系。以酶解修饰蛋白质产品的氮溶解指数、保水率、单分子层水含量为指标,测定水解度(Drgree of Hydrolysis,DH)为1%、2%的8种大豆蛋白酶解修饰产品的溶解性、保水性与水吸附作用。结果表明,限制性酶解修饰处理后,酶解修饰产品的溶解性、保水性、水吸附作用的变化与酶解模式或DH有关;大豆浓缩蛋白经胰蛋白酶修饰至DH为1%,可以显著提高修饰产品的溶解性和保水性;大豆分离蛋白经胰蛋白酶或中性蛋白酶修饰后,可改善溶解性但破坏其保水性;大豆浓缩蛋白、分离蛋白的限制性酶解修饰处理,可以提高修饰产品对水的吸附作用。展开更多
Laboratory tests under different constraint conditions were carried out to obtain the soil-water retention curves(SWRCs) of highly-compacted confined/unconfined Gaomiaozi(GMZ) bentonite at 20,40 and 80 ℃,respectively...Laboratory tests under different constraint conditions were carried out to obtain the soil-water retention curves(SWRCs) of highly-compacted confined/unconfined Gaomiaozi(GMZ) bentonite at 20,40 and 80 ℃,respectively. The effect of temperature on the soil-water characteristics of the highly-compacted GMZ bentonite was analyzed. The results show that the water retention capacity of the highly-compacted GMZ bentonite decreases as the temperature increases under unconfined and confined conditions. At a certain temperature,the constraint conditions have little influence on the water retention capacity of the compacted bentonite at high suction,but the water retention capacity of the confined specimen is lower than that of the unconfined specimen at low suction. Under unconfined conditions,the hysteretic behaviour of the compacted bentonite decreases with increasing temperature. At high suction(>4 MPa) ,the hysteretic behaviour of the unconfined bentonite tends to increase with the decrease of the suction. In summary,the hysteretic behaviour of the compacted bentonite is not significant.展开更多
文摘Nutrient retention capacity by the land/water ecotone soil of Lake Baiyangdian was studied by means of simulation in situ. The results from column experiments suggested that the standard capacity for phosphorus adsorption be less than P14 mg·kg -1 soil in order to meet the lake water quality regulation (P 0.1 mg·L -1 ). Thus the 9,333 hectares of ecotone around the lake could retain 1,245 tons phosphorus in the upper 50-cm soil without degrading the water quality. The amount was nearly 24 times large as that of taken by annual reed harvesting. The maximum capacity for phosphorus was measured as P 774 mg·kg -1 soil. The isothermal equation of phosphorus was also obtained. It was found that temperature had a significant effect on the transformation of nitrogen, and higher temperature would accelerated the nitrification rate. Nitrogen retention was conducted by the microbial activities in the soil and the uptake through aquatic vegetation. The research will benefit for better utilization of local ecotone and design of the planning project which aims to water eutrophication control.
文摘Biochar, as a kind of soil amendment, has important effects on soil water retention. In this research, 4 different kinds of biochars were used to investigate their influences on hydraulic properties and water evaporation in a sandy soil from Hebei Province, China. Biochar had strong absorption ability in the sandy soil. The ratio of water content in the biochar to that in the sandy soil was less than the corresponding ratio of porosity. Because of the different hydraulic properties between the sandy soil and the biochar, the saturated hydraulic conductivity of the sandy soil gradually decreased with the increasing biochar addition. The biochar with larger pore volume and average pore diameter had better water retention. More water was retained in the sandy soil when the biochar was added in a single layer, but not when the biochar was uniformly mixed with soil. Particle size of the added biochar had a significant influence on the hydraulic properties of the mixture of sand and biochar. Grinding the biochar into powder destroyed the pore structure, which simultaneously reduced the water absorption ability and hydraulic conductivity of the biochar. For this reason, adding biochar powder to the sandy soil would not decrease the water evaporation loss of the soil itself.
基金Supported by ENRESA and European Commission(EC Contracts FI4W-CT95-006,FIKW-CT-2000-00016,FI6W-CT-2003-02389)
文摘The bentonite barrier of underground repositories for high-level radioactive waste will be hydrated by the groundwater while it is subjected to high temperatures due to the radioactive decay of the wastes. These changes of temperature affect the hydraulic and mechanical responses of bentonite, which has important effects on design and performance of repositories. The temperature influence on the hydro-mechanical behaviour of bentonite was studied in this paper by experiments, which were carried out with the Spanish FEBEX bentonite compacted at dry densities expected in the＇ repository （from 1.5 to 1.8 Mg/m^3）. The dependence of the swelling strains of bentonite on the temperature has been measured from 30℃ to 90 ℃. At high temperatures the swelling capacity of clay slightly decreases. Also, a clear decrease of swelling pressure as a function of temperature was observed for the same dry densities. Nevertheless, the deformation of bentonite is more dependent on the stress than the temperature. An increase in the permeability of water saturated bentonite with temperature has also been detected. The water retention curves of bentonite compacted at different dry densities were determined under isochoric conditions and in the range of temperatures from 20 ℃ to 120℃. For a given density and water content, the suction decreases as the temperature increases at a rate, which is larger than the one predicted on the basis of water surface tension changing with temperature. Mechanisms related to the physico-chemical interactions that take place at microscopic level, in particular the transfer of interlayer water to the macropores triggered by temperature, seem to explain qualitatively the experimental observations.
文摘为改善大豆蛋白的功能性质,利用中性蛋白酶和胰蛋白酶对大豆浓缩蛋白、分离蛋白进行限制性酶解处理,并考察相应产品的酶解修饰模式与溶解性、保水性变化的关系。以酶解修饰蛋白质产品的氮溶解指数、保水率、单分子层水含量为指标,测定水解度(Drgree of Hydrolysis,DH)为1%、2%的8种大豆蛋白酶解修饰产品的溶解性、保水性与水吸附作用。结果表明,限制性酶解修饰处理后,酶解修饰产品的溶解性、保水性、水吸附作用的变化与酶解模式或DH有关;大豆浓缩蛋白经胰蛋白酶修饰至DH为1%,可以显著提高修饰产品的溶解性和保水性;大豆分离蛋白经胰蛋白酶或中性蛋白酶修饰后,可改善溶解性但破坏其保水性;大豆浓缩蛋白、分离蛋白的限制性酶解修饰处理,可以提高修饰产品对水的吸附作用。
基金Projects(40772180, 40572161, 40802064) supported by the National Natural Science Foundation of ChinaProject ([2007]831) supported by Commission of Science, Technology and Industry for National Defense of China+3 种基金Project(07JJ4012) supported by Hunan Provincial Natural Science Foundation of ChinaProject(20080430680) supported by China Postdoctoral Science FoundationProject(08R214155) supported by Shanghai Postdoctoral Scientific Program of ChinaProject(B308) supported by Shanghai Leading Academic Discipline Project of China
文摘Laboratory tests under different constraint conditions were carried out to obtain the soil-water retention curves(SWRCs) of highly-compacted confined/unconfined Gaomiaozi(GMZ) bentonite at 20,40 and 80 ℃,respectively. The effect of temperature on the soil-water characteristics of the highly-compacted GMZ bentonite was analyzed. The results show that the water retention capacity of the highly-compacted GMZ bentonite decreases as the temperature increases under unconfined and confined conditions. At a certain temperature,the constraint conditions have little influence on the water retention capacity of the compacted bentonite at high suction,but the water retention capacity of the confined specimen is lower than that of the unconfined specimen at low suction. Under unconfined conditions,the hysteretic behaviour of the compacted bentonite decreases with increasing temperature. At high suction(>4 MPa) ,the hysteretic behaviour of the unconfined bentonite tends to increase with the decrease of the suction. In summary,the hysteretic behaviour of the compacted bentonite is not significant.
