The insensitive munitions compound nitroguanidine(NQ)is used by the U.S.Army to avoid unintended explosions.However,NQ also represents an emerging contaminant whose environmental emissions can cause toxicity toward aq...The insensitive munitions compound nitroguanidine(NQ)is used by the U.S.Army to avoid unintended explosions.However,NQ also represents an emerging contaminant whose environmental emissions can cause toxicity toward aquatic organisms,indicating the need for effective remediation strategies.Thus,we investigated the feasibility of treating water contaminated with NQ in continuous-flow columns packed with zero-valent iron(ZVI)or iron sulfide(FeS).Initially,the impact of pH on NQ transformation by ZVI or FeS was evaluated in batch experiments.The pseudo first-order rate constant for NQ transformation(k_(1,NQ))by ZVI was 8-10 times higher at pH 3.0 compared to pH 5.5 and 7.0,whereas similar k_(1,NQ)values were obtained for FeS at pH 5.5-10.0.Based on these findings,the influent p H fed to the ZVIand Fe S-packed columns was adjusted to 3.0 and 5.5,respectively.Both reactors transformed NQ into nitrosoguanidine(Nso Q).Further transformation of Nso Q by ZVI produced aminoguanidine,guanidine,and cyanamide,whereas Nso Q transformation by Fe S produced guanidine,ammonium,and traces of urea.ZVI outperformed Fe S as a reactive material to remove NQ.The ZVI-packed column effectively removed NQ below detection even after 45 d of operation(490 pore volumes,PV).In contrast,NQ breakthrough(removal efficiency<85%)was observed after 18 d(180 PV)in the Fe S-packed column.The high NQ removal efficiency and long service life of the ZVI-packed column(>490 PV)suggest that the technology is a promising approach for NQ treatment in packed-bed reactors and in situ remediation.展开更多
Ammonium and nitrite are two substrates of anammox bacteria, but they are also inhibitors under high concentrations. The performance of two anaerobic ammonium-oxidizing (anammox) upflow biofilm (UBF) reactors was inve...Ammonium and nitrite are two substrates of anammox bacteria, but they are also inhibitors under high concentrations. The performance of two anaerobic ammonium-oxidizing (anammox) upflow biofilm (UBF) reactors was investigated. The results show that anammox UBFs become unstable under nitrogen loading rate (NLR) applied higher than 1.0 g/(L·d). The consumptions of acidity in the anammox reaction lead to the increase of pH, which is as high as 8.70-9.05. Free nitrous acid concentration is accompanied to be lower than the affinity constant of anammox bacteria, and then starvation effect appears. Moreover, free ammonia concentration increases to 57-178 mg/L, resulting in inhibitory effect on the anammox bacteria. Both negative effects contribute to the instability of the anammox bioreactors.展开更多
The aniline degradation by persulfate activated with ferrous ion (Fe2+ ) was investigated in batch reactor at ambient temperature. The experimental factors in aqueous solutions including persulfate concentration, Fe2+...The aniline degradation by persulfate activated with ferrous ion (Fe2+ ) was investigated in batch reactor at ambient temperature. The experimental factors in aqueous solutions including persulfate concentration, Fe2+ concentration, pH and ionic strength level were discussed. It is demonstrated that, aniline degradation rate increases with increasing persulfate concentration, but much more ferrous ion inhibits the aniline degradation. When the aniline concentration is 0.10 mmol/L, the maximum aniline degradation occurs at the S2O82- to Fe2+ molar ratio of 250/5 at pH 7.0. In the pH range of 5.0-8.5, increasing pH causes higher aniline degradation. What's more, the increase of ionic strength in solution causes inhibiting in the reaction. Produced intermediates during the oxidation process were identified using gas chromatography-mass spectrometry (GC-MS) technology. And degradation pathways of aniline were also tentatively proposed.展开更多
Fault prediction technology of running state of electromechanical systems is one of the key technologies that ensure safe and reliable operation of electromechanical equipment in health state. For multiple types of mo...Fault prediction technology of running state of electromechanical systems is one of the key technologies that ensure safe and reliable operation of electromechanical equipment in health state. For multiple types of modern, high-end and key electromechanical equipment, this paper will describe the early faults prediction method for multi-type electromechanical systems, which is favorable for predicting early faults of complex electromechanical systems in non-stationary, nonlinear, variable working conditions and long-time running state; the paper shall introduce the reconfigurable integration technology of series safety monitoring systems based on which the integrated development platform of series safety monitoring systems is built. This platform can adapt to integrated R&D of series safety monitoring systems characterized by high technology, multiple species and low volume. With the help of this platform, series safety monitoring systems were developed, and the Remote Network Security Monitoring Center for Facility Groups was built. Experimental research and engineering applications show that: this new fault prediction method has realized the development trend features extraction of typical electromechanical systems, multi-information fusion, intelligent information decision-making and so on, improving the processing accuracy, relevance and applicability of information; new reconfigurable integration technologies have improved the integration level and R&D efficiency of series safety monitoring systems as well as expanded the scope of application; the series safety monitoring systems developed based on reconfigurable integration platform has already played an important role in many aspects including ensuring safety operation of equipment, stabilizing product quality, optimizing running state, saving energy consumption, reducing environmental pollution, improving working conditions, carrying out scientific maintenance, advancing equipment utilization, saving maintenance charge and enhancing the level of information management.展开更多
The sewage sludge was used to produce adsorbent by controlling the pyrolytic and chemical conditions. Using the adsorbent derived from sewage sludge to adsorb the low concentration SO2 in fixed bed system, the effects...The sewage sludge was used to produce adsorbent by controlling the pyrolytic and chemical conditions. Using the adsorbent derived from sewage sludge to adsorb the low concentration SO2 in fixed bed system, the effects of the metallic derivatives on characteristics of the adsorbent were investigated at different compositions of the gaseous mixtures. The results show that when the mass fraction of vanadium reaches 0.5% and the mass fraction of （iron,） calcium, copper, nickel reach approximately 0.9%, under the condition that the adsorption mixture contains （0.12%SO2,） 3%O2 and 10% water vapor, the maximum adsorption capacity of SO2 can be obtained to be 128, 109, 90, 82, 78 mg·g-1, respectively. So the metallic derivatives fixed onto adsorbent derived from sewage sludge especially vanadium have great effects on of the sorption characteristics of the adsorbent with respect to SO2.展开更多
Pesticide contamination causes precarious implications on human health and environment.Thus the investigation of its sorption phenomenon is highly imperative.Endosulfan insecticide was examined for its adsorption beha...Pesticide contamination causes precarious implications on human health and environment.Thus the investigation of its sorption phenomenon is highly imperative.Endosulfan insecticide was examined for its adsorption behavior on ten assorted soils through batch equilibrium method.Adsorption coefficient values(Kd)ranged from 1.4μg/mL to 18μg/mL.The highest Kd value was obtained for Peshawar soil owing to the presence of highest amount of organic matter(1.4%).Negative values of Gibbs free energy displayed a low interaction between soil and pesticide,exhibiting that the reaction was physiosorption and exothermic in nature.Statistical analysis showed a negative correlation of soil pH and Kd(R^2=–0.77 and p=0.03)and a positive correlation with organic matter(R^2=0.96).Activated carbon prepared from Saccharum officinarum bagasse removed significant amount pesticide.The maximum removal observed was 93%and 97%in 5×10^–6 and 7.5×10^–6,respectively.Activated carbon prepared from biomass for removal purposes was proved to be highly efficient and cost effective.展开更多
Based on Fermat’s principle, two-point ray tracing method was studied in three-dimensional structure. By means of first order Taylor’s incomplete series expansion (i.e. no expansion to the length of the ray), a symm...Based on Fermat’s principle, two-point ray tracing method was studied in three-dimensional structure. By means of first order Taylor’s incomplete series expansion (i.e. no expansion to the length of the ray), a symmetry block tridiagonal matrix equation set was deduced. Further, the positive definiteness of coefficient matrix was discussed, and the positive definiteness was accurately proved in a mathematical way. It assured that the algorithm was well-posed. Associated with iterative method, the solution to ray tracing can be got through step-by-step linearized iteration of the nonlinear problem. An algorithm of the whole path iterative ray tracing method in three-dimensional velocity structure was obtained. This method shows a clear and simple as well as explicit computation formula, which makes ray tracing computation easily applicable in practice. The correction vector is obtained through finding the solution to the positive definite block tridiagonal equation set, which ensures the method is robust convergence. This study offers a new kind of feasible and efficient ray tracing method for three dimensional seismic migration and tomography. Meanwhile, it also provides the prerequisite guarantee to design a fast algorithm.展开更多
The concentration of heavy metals was investigated in black soil samples collected from the fields treated with chemical in Bayan County which were from the vegetation covers,bare soil and grain fields without any che...The concentration of heavy metals was investigated in black soil samples collected from the fields treated with chemical in Bayan County which were from the vegetation covers,bare soil and grain fields without any chemical treatments in Hailun National Field Research Station of Agroecosystem,Chinese Academy of Sciences (CAS) in July,2009.Results showed that the presence of significantly high concentration of zinc (Zn) and lead (Pb) in soils covered with grass vegetation.However,mercury (Hg),copper (Cu),nick...展开更多
The tailing soils were from 10 mining areas in Hunan Province. To predict the potential impact of tailings on nearby environments, the characteristics such as the pH value, loss on ignition, cation exchange capacity, ...The tailing soils were from 10 mining areas in Hunan Province. To predict the potential impact of tailings on nearby environments, the characteristics such as the pH value, loss on ignition, cation exchange capacity, and the concentration and speciation of heavy metals in the tailings were investigated. Based on these characteristics, the pollution index and danger index were calculated so as to evaluate the priorities of remediation. The results show that the concentrations of Pb, Cd, Cu and Zn exceed the tolerable levels of the phytotoxicity in the most tailings. The large proportion of heavy metals exists in the form of residual fraction in most tailings, followed by sulfides/organic and Fe/Mn oxide fractions, and a little in the exchangeable and carbonate fraction. The calculated pollution indices for the tailing samples range from 1.41 to 83.42, which indicates that all the tailings contain heavy metals at a level that causes toxicity to the ecosystem. The danger indices for the tailing samples range from 0.06 to 387.00. The highest value of the danger indices is that of Yongzhou sample, reaching 387.00; the lowest one is that of Xikuangshan sample, only 0.06. Considering the results of pollution index and danger index in combination, the priority of remediation is determined to be Yongzhou, Baoshan, Xiangtan and Lengshuijiang.展开更多
The rapid increase of urban population in coastal areas of developing countries is nowadays a widespread phenomenon that has several environmental, economical and social consequences.Internal migration, spread of info...The rapid increase of urban population in coastal areas of developing countries is nowadays a widespread phenomenon that has several environmental, economical and social consequences.Internal migration, spread of informal suburban settlements,lack of adequate sanitation,increase in water extraction。展开更多
The present study is aimed at calculating domestic solid waste water in Sari city,Mazandaran.Solid waste management mainly involves management of activities that are engineering oriented such as waste generation,stora...The present study is aimed at calculating domestic solid waste water in Sari city,Mazandaran.Solid waste management mainly involves management of activities that are engineering oriented such as waste generation,storage,collection,transportation,operation of processing and disposal facilities.A small composting unit is suggested for the composting of solid waste in community or colony level so that the community committee itself can maintain the composting unit.The study is to analyze the solid waste disposal system and suggest suitable modification in the present system to improve the展开更多
The Myankaleh Wildlife Refuge is involved in quartet areas management that the Environment Conservation Organization has dedicated to conserving and reviving plants and animals societies,which are the remains of the K...The Myankaleh Wildlife Refuge is involved in quartet areas management that the Environment Conservation Organization has dedicated to conserving and reviving plants and animals societies,which are the remains of the Khazar plain forest.This refuge includes two remarkable ecosystems of Myankaleh lagoon and a peninsula considered to be an important habitat of migrated fowl and waterfowls.In the past this region was a habitat for several mammals like Panthera tigris,Cervus elaphus,Panthera pardus, Canis lupus and Acinonyx jubatus while now it is known as a winter resort for several bird展开更多
Organoclays synthesized with small organic cations can effectively adsorb hydrophobic organic compounds (HOCs), and the hydrophobic siloxane surfaces of clay minerals have been considered as the main adsorption sites ...Organoclays synthesized with small organic cations can effectively adsorb hydrophobic organic compounds (HOCs), and the hydrophobic siloxane surfaces of clay minerals have been considered as the main adsorption sites for HOCs. Therefore, reducing charge density of clay minerals which can effectively increase the exposed siloxane surface areas has been generally used to enhance the adsorption capacity of organoclays towards HOCs. In this work, we will present a new method to increase the exposed siloxane surface areas of the synthesized organoclays and enhance their adsorption capacity. Firstly, the original inorganic cations on montmorillonite were exchanged with Li+, and then part of the Li+ (i.e., 20% to 60% of the montmorillonite’s CEC) were further exchanged with tetramethylammonium cation (TMA). After that ,the samples were heated at 200 ℃ for 12 h to make sure most of the Li+ were transferred to montmorillonite layers. With this method the layer charge of montmorillonite can be effectively reduced while the layered structure of montmorillonite will be preserved by pre-exchanged TMA. Finally, the remaining Li+ cations were further exchanged with TMA. The structural and adsorptive characteristics of the resulting organoclays were compared with those synthesized using traditional method (i.e., first reducing the charge density and then exchanging TMA).展开更多
A model for liquid-gas flow （MLGF）, considering the flee movement of liquid surface, was built to simulate the wastewater velocity field and gas distribution in a full-scale Caroussel oxidation ditch with surface ae...A model for liquid-gas flow （MLGF）, considering the flee movement of liquid surface, was built to simulate the wastewater velocity field and gas distribution in a full-scale Caroussel oxidation ditch with surface aeration. It was calibrated and validated by field measurement data, and the calibrated parameters and sections were selected based on both model analysis and numerical computation. The simulated velocities of MLGF were compared to that of a model for wastewater-sludge flow （MWSF）. The results show that the free liquid surface considered in MLGF improves the simulated velocity results of upper layer and surface. Moreover, distribution of gas volume fraction （GVF） simulated by MLGF was compared to dissolved oxygen （DO） measured in the oxidation ditch. It is shown that DO distribution is affected by many factors besides GVF distribution.展开更多
在对我国南方3种典型的水稻土有机碳团聚体分布研究的基础上,对用低能量超声波分散法分离得到的团聚体颗粒组进一步进行有机碳键合形态分析,考察不同键合态有机碳在不同粒径团聚体的分布,由此探讨这些水稻土中有机碳积累中物理作用基础...在对我国南方3种典型的水稻土有机碳团聚体分布研究的基础上,对用低能量超声波分散法分离得到的团聚体颗粒组进一步进行有机碳键合形态分析,考察不同键合态有机碳在不同粒径团聚体的分布,由此探讨这些水稻土中有机碳积累中物理作用基础上的化学机制。结果表明:钙键合态有机碳(Ca-SOC)多分布于2 000～200μm的粗团聚体颗粒组中,且在紫色水稻土中含量最高(达到9 g kg-1左右),而红壤性水稻土中最低(不到3 g kg-1);相反,铁铝键合态有机碳(Fe(Al)-SOC)趋向于在细团聚体颗粒组集中,是<2μm颗粒组中有机碳的优势组分,且以红壤性水稻土中最高(介于20～30 g kg-1之间),紫色水稻土中最低(仅为10 g kg-1左右),这与该团聚体颗粒组中铁铝氧化物的含量分布相吻合。统计分析表明,易氧化态碳(LOC)占有机碳(SOC)的比值与Ca-SOC占SOC的比值表现为正相关关系,而与Fe(Al)-SOC占SOC的比值表现为反相关关系。直径为2 000～200μm的粗团聚体中的Ca-SOC和Fe(Al)-SOC对长期不同耕作和施肥的响应最为敏感,良好的耕作施肥下水稻土有机碳的积累主要表现为Fe(Al)-SOC的增加。氧化铁铝的含量与SOC和LOC的含量之间存在一定的依变关系,说明这些土壤发生的无机组成分在有机碳的保护与稳定中发挥着重要作用,并且以红壤性水稻土粗团聚体中的氧化铁铝对有机碳的保护作用最强。由此看来,团聚体更新中物理保护的有机碳在细团聚体形成中进一步与氧化铁铝的键合可能是这些水稻土中有机碳稳定的重要机制。展开更多
基金financially supported by the Strategic Environmental Research and Development Program(Grant No.ER19-1075)。
文摘The insensitive munitions compound nitroguanidine(NQ)is used by the U.S.Army to avoid unintended explosions.However,NQ also represents an emerging contaminant whose environmental emissions can cause toxicity toward aquatic organisms,indicating the need for effective remediation strategies.Thus,we investigated the feasibility of treating water contaminated with NQ in continuous-flow columns packed with zero-valent iron(ZVI)or iron sulfide(FeS).Initially,the impact of pH on NQ transformation by ZVI or FeS was evaluated in batch experiments.The pseudo first-order rate constant for NQ transformation(k_(1,NQ))by ZVI was 8-10 times higher at pH 3.0 compared to pH 5.5 and 7.0,whereas similar k_(1,NQ)values were obtained for FeS at pH 5.5-10.0.Based on these findings,the influent p H fed to the ZVIand Fe S-packed columns was adjusted to 3.0 and 5.5,respectively.Both reactors transformed NQ into nitrosoguanidine(Nso Q).Further transformation of Nso Q by ZVI produced aminoguanidine,guanidine,and cyanamide,whereas Nso Q transformation by Fe S produced guanidine,ammonium,and traces of urea.ZVI outperformed Fe S as a reactive material to remove NQ.The ZVI-packed column effectively removed NQ below detection even after 45 d of operation(490 pore volumes,PV).In contrast,NQ breakthrough(removal efficiency<85%)was observed after 18 d(180 PV)in the Fe S-packed column.The high NQ removal efficiency and long service life of the ZVI-packed column(>490 PV)suggest that the technology is a promising approach for NQ treatment in packed-bed reactors and in situ remediation.
基金Project(2006AA06Z332) supported by the National High-Tech Research and Development Program of ChinaProject(30770039) supported by the National Natural Science Foundation of ChinaProject(2008BADC4B05) supported by the National Science and Technology Pillar Program
文摘Ammonium and nitrite are two substrates of anammox bacteria, but they are also inhibitors under high concentrations. The performance of two anaerobic ammonium-oxidizing (anammox) upflow biofilm (UBF) reactors was investigated. The results show that anammox UBFs become unstable under nitrogen loading rate (NLR) applied higher than 1.0 g/(L·d). The consumptions of acidity in the anammox reaction lead to the increase of pH, which is as high as 8.70-9.05. Free nitrous acid concentration is accompanied to be lower than the affinity constant of anammox bacteria, and then starvation effect appears. Moreover, free ammonia concentration increases to 57-178 mg/L, resulting in inhibitory effect on the anammox bacteria. Both negative effects contribute to the instability of the anammox bioreactors.
基金Project partly supported by a Grant from E.I. du Pont de Nemours and Company to Rutgers UniversityProject(2010B05020007) supported by the Foundation of Science and Technology Planning of Guangdong Province, China+2 种基金Project(2011ZM0054) supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2011K0013) supported by the Research Fund Program of Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, ChinaProject supported by the Research Fund of Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, China
文摘The aniline degradation by persulfate activated with ferrous ion (Fe2+ ) was investigated in batch reactor at ambient temperature. The experimental factors in aqueous solutions including persulfate concentration, Fe2+ concentration, pH and ionic strength level were discussed. It is demonstrated that, aniline degradation rate increases with increasing persulfate concentration, but much more ferrous ion inhibits the aniline degradation. When the aniline concentration is 0.10 mmol/L, the maximum aniline degradation occurs at the S2O82- to Fe2+ molar ratio of 250/5 at pH 7.0. In the pH range of 5.0-8.5, increasing pH causes higher aniline degradation. What's more, the increase of ionic strength in solution causes inhibiting in the reaction. Produced intermediates during the oxidation process were identified using gas chromatography-mass spectrometry (GC-MS) technology. And degradation pathways of aniline were also tentatively proposed.
基金Supported by National Natural Science Fund Project(51275052)Key project supported by Beijing Municipal Natural Science Foundation(3131002)Open topic of Key Laboratory of Key Laboratory of Modern Measurement & Control Technology,Ministry of Education(KF20141123202,KF20111123201)
文摘Fault prediction technology of running state of electromechanical systems is one of the key technologies that ensure safe and reliable operation of electromechanical equipment in health state. For multiple types of modern, high-end and key electromechanical equipment, this paper will describe the early faults prediction method for multi-type electromechanical systems, which is favorable for predicting early faults of complex electromechanical systems in non-stationary, nonlinear, variable working conditions and long-time running state; the paper shall introduce the reconfigurable integration technology of series safety monitoring systems based on which the integrated development platform of series safety monitoring systems is built. This platform can adapt to integrated R&D of series safety monitoring systems characterized by high technology, multiple species and low volume. With the help of this platform, series safety monitoring systems were developed, and the Remote Network Security Monitoring Center for Facility Groups was built. Experimental research and engineering applications show that: this new fault prediction method has realized the development trend features extraction of typical electromechanical systems, multi-information fusion, intelligent information decision-making and so on, improving the processing accuracy, relevance and applicability of information; new reconfigurable integration technologies have improved the integration level and R&D efficiency of series safety monitoring systems as well as expanded the scope of application; the series safety monitoring systems developed based on reconfigurable integration platform has already played an important role in many aspects including ensuring safety operation of equipment, stabilizing product quality, optimizing running state, saving energy consumption, reducing environmental pollution, improving working conditions, carrying out scientific maintenance, advancing equipment utilization, saving maintenance charge and enhancing the level of information management.
文摘The sewage sludge was used to produce adsorbent by controlling the pyrolytic and chemical conditions. Using the adsorbent derived from sewage sludge to adsorb the low concentration SO2 in fixed bed system, the effects of the metallic derivatives on characteristics of the adsorbent were investigated at different compositions of the gaseous mixtures. The results show that when the mass fraction of vanadium reaches 0.5% and the mass fraction of （iron,） calcium, copper, nickel reach approximately 0.9%, under the condition that the adsorption mixture contains （0.12%SO2,） 3%O2 and 10% water vapor, the maximum adsorption capacity of SO2 can be obtained to be 128, 109, 90, 82, 78 mg·g-1, respectively. So the metallic derivatives fixed onto adsorbent derived from sewage sludge especially vanadium have great effects on of the sorption characteristics of the adsorbent with respect to SO2.
文摘Pesticide contamination causes precarious implications on human health and environment.Thus the investigation of its sorption phenomenon is highly imperative.Endosulfan insecticide was examined for its adsorption behavior on ten assorted soils through batch equilibrium method.Adsorption coefficient values(Kd)ranged from 1.4μg/mL to 18μg/mL.The highest Kd value was obtained for Peshawar soil owing to the presence of highest amount of organic matter(1.4%).Negative values of Gibbs free energy displayed a low interaction between soil and pesticide,exhibiting that the reaction was physiosorption and exothermic in nature.Statistical analysis showed a negative correlation of soil pH and Kd(R^2=–0.77 and p=0.03)and a positive correlation with organic matter(R^2=0.96).Activated carbon prepared from Saccharum officinarum bagasse removed significant amount pesticide.The maximum removal observed was 93%and 97%in 5×10^–6 and 7.5×10^–6,respectively.Activated carbon prepared from biomass for removal purposes was proved to be highly efficient and cost effective.
基金Project(40674071) supported by the National Natural Science Foundation of Chinaproject(KFAS2002-2003) supported by Korea Foundation for Advanced Studies
文摘Based on Fermat’s principle, two-point ray tracing method was studied in three-dimensional structure. By means of first order Taylor’s incomplete series expansion (i.e. no expansion to the length of the ray), a symmetry block tridiagonal matrix equation set was deduced. Further, the positive definiteness of coefficient matrix was discussed, and the positive definiteness was accurately proved in a mathematical way. It assured that the algorithm was well-posed. Associated with iterative method, the solution to ray tracing can be got through step-by-step linearized iteration of the nonlinear problem. An algorithm of the whole path iterative ray tracing method in three-dimensional velocity structure was obtained. This method shows a clear and simple as well as explicit computation formula, which makes ray tracing computation easily applicable in practice. The correction vector is obtained through finding the solution to the positive definite block tridiagonal equation set, which ensures the method is robust convergence. This study offers a new kind of feasible and efficient ray tracing method for three dimensional seismic migration and tomography. Meanwhile, it also provides the prerequisite guarantee to design a fast algorithm.
基金Supported by Knowledge Innovation Program of Chinese Academy of Sciences (KSCX-YW-09)Technological Key Projects Undertaken During "11th Five Year" Period in Heilongjiang Province (GA06B101)
文摘The concentration of heavy metals was investigated in black soil samples collected from the fields treated with chemical in Bayan County which were from the vegetation covers,bare soil and grain fields without any chemical treatments in Hailun National Field Research Station of Agroecosystem,Chinese Academy of Sciences (CAS) in July,2009.Results showed that the presence of significantly high concentration of zinc (Zn) and lead (Pb) in soils covered with grass vegetation.However,mercury (Hg),copper (Cu),nick...
基金Project (2001AA644020) supported by the National"863"High Technology Research and Development Program of China
文摘The tailing soils were from 10 mining areas in Hunan Province. To predict the potential impact of tailings on nearby environments, the characteristics such as the pH value, loss on ignition, cation exchange capacity, and the concentration and speciation of heavy metals in the tailings were investigated. Based on these characteristics, the pollution index and danger index were calculated so as to evaluate the priorities of remediation. The results show that the concentrations of Pb, Cd, Cu and Zn exceed the tolerable levels of the phytotoxicity in the most tailings. The large proportion of heavy metals exists in the form of residual fraction in most tailings, followed by sulfides/organic and Fe/Mn oxide fractions, and a little in the exchangeable and carbonate fraction. The calculated pollution indices for the tailing samples range from 1.41 to 83.42, which indicates that all the tailings contain heavy metals at a level that causes toxicity to the ecosystem. The danger indices for the tailing samples range from 0.06 to 387.00. The highest value of the danger indices is that of Yongzhou sample, reaching 387.00; the lowest one is that of Xikuangshan sample, only 0.06. Considering the results of pollution index and danger index in combination, the priority of remediation is determined to be Yongzhou, Baoshan, Xiangtan and Lengshuijiang.
文摘The rapid increase of urban population in coastal areas of developing countries is nowadays a widespread phenomenon that has several environmental, economical and social consequences.Internal migration, spread of informal suburban settlements,lack of adequate sanitation,increase in water extraction。
文摘The present study is aimed at calculating domestic solid waste water in Sari city,Mazandaran.Solid waste management mainly involves management of activities that are engineering oriented such as waste generation,storage,collection,transportation,operation of processing and disposal facilities.A small composting unit is suggested for the composting of solid waste in community or colony level so that the community committee itself can maintain the composting unit.The study is to analyze the solid waste disposal system and suggest suitable modification in the present system to improve the
文摘The Myankaleh Wildlife Refuge is involved in quartet areas management that the Environment Conservation Organization has dedicated to conserving and reviving plants and animals societies,which are the remains of the Khazar plain forest.This refuge includes two remarkable ecosystems of Myankaleh lagoon and a peninsula considered to be an important habitat of migrated fowl and waterfowls.In the past this region was a habitat for several mammals like Panthera tigris,Cervus elaphus,Panthera pardus, Canis lupus and Acinonyx jubatus while now it is known as a winter resort for several bird
文摘Organoclays synthesized with small organic cations can effectively adsorb hydrophobic organic compounds (HOCs), and the hydrophobic siloxane surfaces of clay minerals have been considered as the main adsorption sites for HOCs. Therefore, reducing charge density of clay minerals which can effectively increase the exposed siloxane surface areas has been generally used to enhance the adsorption capacity of organoclays towards HOCs. In this work, we will present a new method to increase the exposed siloxane surface areas of the synthesized organoclays and enhance their adsorption capacity. Firstly, the original inorganic cations on montmorillonite were exchanged with Li+, and then part of the Li+ (i.e., 20% to 60% of the montmorillonite’s CEC) were further exchanged with tetramethylammonium cation (TMA). After that ,the samples were heated at 200 ℃ for 12 h to make sure most of the Li+ were transferred to montmorillonite layers. With this method the layer charge of montmorillonite can be effectively reduced while the layered structure of montmorillonite will be preserved by pre-exchanged TMA. Finally, the remaining Li+ cations were further exchanged with TMA. The structural and adsorptive characteristics of the resulting organoclays were compared with those synthesized using traditional method (i.e., first reducing the charge density and then exchanging TMA).
基金Project supported by Visiting Scholar Foundation of Key Laboratory of the Resources Exploitation and Environmental Disaster Control Engineering in Southwest China (Chongqing University),Ministry of Education,China
文摘A model for liquid-gas flow （MLGF）, considering the flee movement of liquid surface, was built to simulate the wastewater velocity field and gas distribution in a full-scale Caroussel oxidation ditch with surface aeration. It was calibrated and validated by field measurement data, and the calibrated parameters and sections were selected based on both model analysis and numerical computation. The simulated velocities of MLGF were compared to that of a model for wastewater-sludge flow （MWSF）. The results show that the free liquid surface considered in MLGF improves the simulated velocity results of upper layer and surface. Moreover, distribution of gas volume fraction （GVF） simulated by MLGF was compared to dissolved oxygen （DO） measured in the oxidation ditch. It is shown that DO distribution is affected by many factors besides GVF distribution.
基金Project(202203021212308)supported by the Fundamental Research Program of Shanxi Province,ChinaProject(HZKY20220508)supported by the Ministry of Education’s“Chunhui Plan”Cooperative Scientific Research Project,China+5 种基金Project(KF-22-16)supported by the Open Fund from the Key Lab of Eco-restoration of Regional Contaminated Environment(Shenyang University)Ministry of Education,ChinaProject(20222020)supported by the Doctoral Foundation of Taiyuan University of Science and Technology,ChinaProject(2022L297)supported by the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province,ChinaProject supported by the Startup Funds of San Diego State University,USAProject(202304051001016)supported by the Special Fund for Science and Technology Innovation Teams of Shanxi Province,China。
文摘在对我国南方3种典型的水稻土有机碳团聚体分布研究的基础上,对用低能量超声波分散法分离得到的团聚体颗粒组进一步进行有机碳键合形态分析,考察不同键合态有机碳在不同粒径团聚体的分布,由此探讨这些水稻土中有机碳积累中物理作用基础上的化学机制。结果表明:钙键合态有机碳(Ca-SOC)多分布于2 000～200μm的粗团聚体颗粒组中,且在紫色水稻土中含量最高(达到9 g kg-1左右),而红壤性水稻土中最低(不到3 g kg-1);相反,铁铝键合态有机碳(Fe(Al)-SOC)趋向于在细团聚体颗粒组集中,是<2μm颗粒组中有机碳的优势组分,且以红壤性水稻土中最高(介于20～30 g kg-1之间),紫色水稻土中最低(仅为10 g kg-1左右),这与该团聚体颗粒组中铁铝氧化物的含量分布相吻合。统计分析表明,易氧化态碳(LOC)占有机碳(SOC)的比值与Ca-SOC占SOC的比值表现为正相关关系,而与Fe(Al)-SOC占SOC的比值表现为反相关关系。直径为2 000～200μm的粗团聚体中的Ca-SOC和Fe(Al)-SOC对长期不同耕作和施肥的响应最为敏感,良好的耕作施肥下水稻土有机碳的积累主要表现为Fe(Al)-SOC的增加。氧化铁铝的含量与SOC和LOC的含量之间存在一定的依变关系,说明这些土壤发生的无机组成分在有机碳的保护与稳定中发挥着重要作用,并且以红壤性水稻土粗团聚体中的氧化铁铝对有机碳的保护作用最强。由此看来,团聚体更新中物理保护的有机碳在细团聚体形成中进一步与氧化铁铝的键合可能是这些水稻土中有机碳稳定的重要机制。
