Forty-eight surface sediments of the southern Yellow Sea are separated into three grain-size frac- tions. Four forms of extractable nitrogen (nitrogen in ion-exchangeable form (Nie), nitrogen in weak-acid ex- tractabl...Forty-eight surface sediments of the southern Yellow Sea are separated into three grain-size frac- tions. Four forms of extractable nitrogen (nitrogen in ion-exchangeable form (Nie), nitrogen in weak-acid ex- tractable form (Nwa), nitrogen in strong-alkali extractable form (Nsa) and nitrogen in strong-oxidant form (Nso)) are obtained by the sequential extraction. The results show that the contents and the distributions of the extract- able nitrogen in the southern Yellow Sea surface sediments are closely related to sediment grain size. The distri- butions of Nie, Nso and total nitrogen (TN) present positive correlations with fine particles content, while Nwa and Nsa does not have such correlation. The net contents of all the forms of nitrogen increase with sediment grain size finer.展开更多
A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sampl...A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sample was typical of superparamagnetic material.The samples were characterized by transmission electron microscope,and it is found that the particles are of small size.The Fe_3O_4/GO MNPs were further used as an adsorbent to remove Rhodamine B.The effects of initial pH of the solution,the dosage of adsorbent,temperature,contact time and the presence of interfering dyes on adsorption performance were investigated as well.The adsorption equilibrium and kinetics data were fitted well with the Freundlich isotherm and the pseudosecond-order kinetic model respectively.The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption of Rhodamine B.And the adsorption process was endothermic in nature.Furthermore,the magnetic composite with a high adsorption capacity of Rhodamine B could be effectively and simply separated using an external magnetic field.And the used particles could be regenerated and recycled easily.The magnetic composite could find potential applications for the removal of dye pollutants.展开更多
Soil-bentonite （SB） vertical slurry cutoff wall is a useful treatment for urban industrial contaminated sites. Due to the clay-heavy metal interaction, significant changes would occur in the engineering behavior of ...Soil-bentonite （SB） vertical slurry cutoff wall is a useful treatment for urban industrial contaminated sites. Due to the clay-heavy metal interaction, significant changes would occur in the engineering behavior of SB cutoff walls. However, previous study is limited to kaolinitic soils or montmorillonitic soils along using solidum chloride and/or calcium chloride as target contaminant. In this work, a series of oedometer tests were conducted to investigate the effects of lead （Pb） on the compressibility and the permeability of kaolin-bentonite （KB） mixtures, a simplified model of in-situ SB cutoff wall backfills. In addition, sedimentation tests were conducted to interpret the mechanism controlling the change of compressibility and permeability from the perspective of soil fabric. The Pb-contaminated KB mixtures for oedometer tests and sedimentation tests were prepared with bentonite contents of 0, 5%, 10%, and 15% by dry mass, and they were mixed with pre-determined volume of lead nitrate solution based on designed Pb concentration and solid-to-solution ratio. The Pb concentration was controlled as 0, 0.1, 0.5, 1.0, 5.0, 10, and 50 mg/g with a solid-to-solution ratio of approximate 0.5. The prepared KB mixtures with bentonite contents of 0, 5%, and 10% were chosen for the sedimentation tests. They were freeze-dried and mixed with DDI with a solid-to-solution ratio of 10 g/100 mL. The results indicate that pH, compressibility, and permeability of KB mixture changed considerably with respect to Pb concentration. It is concluded that the fabric of KB mixture, depending on the particle-particle interaction subjected to different ranges of pH and Pb concentration, governs the sedimentation behavior and permeability. The results of liquid limit （WE） cannot be explained in terms of the sedimentation behavior since it is only ionic-dependent.展开更多
The Yellow River is famous for its complex and unique physical conditions which give great chal- lenges to the river management. Based on the study and analysis of the existing problems and research progress, this pap...The Yellow River is famous for its complex and unique physical conditions which give great chal- lenges to the river management. Based on the study and analysis of the existing problems and research progress, this paper indicated that the most signifi- cant challenges of Yellow River studies are: long term hydrological and morphological changes; the optimized hydrology and sediment conditions to maintain the healthy life of the River; and simulation of Yellow River through mathematical model and physical models.展开更多
基金This project is supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KZCXI-SW-01-08) and the National Science Foundation for Outstanding Young Scientists in China (No.49925614)
文摘Forty-eight surface sediments of the southern Yellow Sea are separated into three grain-size frac- tions. Four forms of extractable nitrogen (nitrogen in ion-exchangeable form (Nie), nitrogen in weak-acid ex- tractable form (Nwa), nitrogen in strong-alkali extractable form (Nsa) and nitrogen in strong-oxidant form (Nso)) are obtained by the sequential extraction. The results show that the contents and the distributions of the extract- able nitrogen in the southern Yellow Sea surface sediments are closely related to sediment grain size. The distri- butions of Nie, Nso and total nitrogen (TN) present positive correlations with fine particles content, while Nwa and Nsa does not have such correlation. The net contents of all the forms of nitrogen increase with sediment grain size finer.
基金Supported by the National Natural Science Foundation of China(21107143,21207033)the Fundamental Research Funds for the Central Universities,South-Central University for Nationalities(CZY15003)
文摘A simple ultrasound-assisted co-precipitation method was developed to prepare ferroferric oxide/graphene oxide magnetic nanoparticles(Fe_3O_4/CO MNPs).The hysteresis loop of Fe_3O_4/GO MNPs demonstrated that the sample was typical of superparamagnetic material.The samples were characterized by transmission electron microscope,and it is found that the particles are of small size.The Fe_3O_4/GO MNPs were further used as an adsorbent to remove Rhodamine B.The effects of initial pH of the solution,the dosage of adsorbent,temperature,contact time and the presence of interfering dyes on adsorption performance were investigated as well.The adsorption equilibrium and kinetics data were fitted well with the Freundlich isotherm and the pseudosecond-order kinetic model respectively.The adsorption process followed intra-particle diffusion model with more than one process affecting the adsorption of Rhodamine B.And the adsorption process was endothermic in nature.Furthermore,the magnetic composite with a high adsorption capacity of Rhodamine B could be effectively and simply separated using an external magnetic field.And the used particles could be regenerated and recycled easily.The magnetic composite could find potential applications for the removal of dye pollutants.
基金Project(51278100) supported by the National Natural Science Foundation of ChinaProjects(BK2010060, BK2012022) supported by the Natural Science Foundation of Jiangsu Province, ChinaProject(103) supported by the Scientific Innovation Research of University Graduate Students of Jiangsu Province, China
文摘Soil-bentonite （SB） vertical slurry cutoff wall is a useful treatment for urban industrial contaminated sites. Due to the clay-heavy metal interaction, significant changes would occur in the engineering behavior of SB cutoff walls. However, previous study is limited to kaolinitic soils or montmorillonitic soils along using solidum chloride and/or calcium chloride as target contaminant. In this work, a series of oedometer tests were conducted to investigate the effects of lead （Pb） on the compressibility and the permeability of kaolin-bentonite （KB） mixtures, a simplified model of in-situ SB cutoff wall backfills. In addition, sedimentation tests were conducted to interpret the mechanism controlling the change of compressibility and permeability from the perspective of soil fabric. The Pb-contaminated KB mixtures for oedometer tests and sedimentation tests were prepared with bentonite contents of 0, 5%, 10%, and 15% by dry mass, and they were mixed with pre-determined volume of lead nitrate solution based on designed Pb concentration and solid-to-solution ratio. The Pb concentration was controlled as 0, 0.1, 0.5, 1.0, 5.0, 10, and 50 mg/g with a solid-to-solution ratio of approximate 0.5. The prepared KB mixtures with bentonite contents of 0, 5%, and 10% were chosen for the sedimentation tests. They were freeze-dried and mixed with DDI with a solid-to-solution ratio of 10 g/100 mL. The results indicate that pH, compressibility, and permeability of KB mixture changed considerably with respect to Pb concentration. It is concluded that the fabric of KB mixture, depending on the particle-particle interaction subjected to different ranges of pH and Pb concentration, governs the sedimentation behavior and permeability. The results of liquid limit （WE） cannot be explained in terms of the sedimentation behavior since it is only ionic-dependent.
文摘The Yellow River is famous for its complex and unique physical conditions which give great chal- lenges to the river management. Based on the study and analysis of the existing problems and research progress, this paper indicated that the most signifi- cant challenges of Yellow River studies are: long term hydrological and morphological changes; the optimized hydrology and sediment conditions to maintain the healthy life of the River; and simulation of Yellow River through mathematical model and physical models.
