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Classical model for diffusion and thermalization of heavy quarks in a hot medium:memory and out-of-equilibrium effects
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作者 Marco Ruggieri Marco Frasca Santosh Kumar Das 《中国物理C:英文版》 SCIE CAS CSCD 2019年第9期90-100,共11页
We consider a simple model for the diffusion of heavy quarks in a hot bath,modeling the latter by an ensemble of oscillators distributed according to either a thermal distribution or to an out-of-equilibrium distribut... We consider a simple model for the diffusion of heavy quarks in a hot bath,modeling the latter by an ensemble of oscillators distributed according to either a thermal distribution or to an out-of-equilibrium distribution with a saturation scale.In this model it is easy to introduce memory effects by changing the distribution of oscillators:we model them by introducing a Gaussian distribution,dN/dω,which can be deformed continuously from aδ?function,giving a Markov dissipation,to a broad kernel with memory.Deriving the equation of motion of the heavy quark in the bath,we remark how dissipation comes out naturally as an effect of the back-reaction of the oscillators on the bath.Moreover,the exact solution of this equation allows to define the thermalization time as the time necessary to remove any memory of the initial conditions.We find that the broadening of the dissipative kernel,while keeping the coupling fixed,lowers the thermalization time.We also derive the fluctuation-dissipation theorem for the bath,and use it to estimate the kinematic regime in which momentum diffusion of the heavy quark dominates over drift.We find that diffusion is more important as long as K0/E is small,where K0 and E denote the initial energy of the heavy quark and the average energy of the bath,respectively. 展开更多
关键词 relativistic HEAVY ion COLLISIONS HEAVY QUARKS BROWNIAN motion MEMORY effect QUARK-GLUON plasma
Heavy fermions in high magnetic fields
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作者 M Smidman 沈斌 +3 位作者 郭春煜 焦琳 路欣 袁辉球 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第1期25-38,共14页
Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low ene... Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low energy scales, the relative strengths of the Ruderman–Kittel–Kasuya–Yosida(RKKY) and Kondo interactions can often be readily tuned by non-thermal control parameters such as pressure, doping, or applied magnetic fields, which can give rise to quantum criticality and unconventional superconductivity. Here we provide a brief overview of research into heavy fermion materials in high magnetic fields, focussing on three main areas. Firstly we review the use of magnetic fields as a tuning parameter,and in particular the ability to realize different varieties of quantum critical behaviors. We then discuss the properties of heavy fermion superconductors in magnetic fields, where experiments in applied fields can reveal the nature of the order parameter, and induce new novel phenomena. Finally we report recent studies of topological Kondo systems, including topological Kondo insulators and Kondo–Weyl semimetals. Here experiments in magnetic fields can be used to probe the topologically non-trivial Fermi surface, as well as related field-induced phenomena such as the chiral anomaly and topological Hall effect. 展开更多
关键词 HEAVY FERMIONS high magnetic fields quantum phase TRANSITIONS HEAVY FERMION SUPERCONDUCTIVITY topological KONDO systems
Spatial Pattern Difference of Contribution between Short and Long-duration Heavy Rainfall to Total Heavy Rainfall in China from 1961 to 2015 预览
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作者 Kong Feng 《气象与环境研究:英文版》 CAS 2019年第4期51-60,共10页
Many regions are pounded with heavy rainfall, causing flood, casualties, property damage and severe destruction to ecosystem in multiple urban areas. Frequent occurrence of extremely heavy precipitation event under th... Many regions are pounded with heavy rainfall, causing flood, casualties, property damage and severe destruction to ecosystem in multiple urban areas. Frequent occurrence of extremely heavy precipitation event under the background of global climate change has caused terrible harm on economic and social development, life security, ecosystem, etc.;brought profound impact on sustainable development of disaster area;become a key factor of global and regional disasters and environmental risk;and been widely concerned by academic circle and all sectors of the society. So severe disasters caused by extreme precipitation events have attracted more and more attention, while the relationship between heavy rainfall with different duration and total heavy rainfall has become the hottest scientific frontier issue. Contribution of heavy rainfall with different duration to the total heavy rainfall has significant spatial differences. Here we used daily rainfall data from 1961 to 2015 of 659 meteorological stations in China. When the rainfall is greater than 50 mm in 24 hours, that is a heavy rainfall event. Heavy rainfall only lasting one day is defined as short- duration heavy rainfall, while heavy rainfall lasting more than two days is defined as long-duration heavy rainfall. Results indicated that: on the basis of duration days defined long-duration heavy rainfall, on the spatial distribution, total rainfall, total heavy rainfall and short-duration heavy rainfall showed "increasing-decreasing-increasing" from the southeast coast to northwest inland in China from 1961 to 2015, and on the whole meteorological station with increasing trend predominant. In the meantime, long-duration heavy rainfall showed "increasing-decreasing" spatial pattern, and on the whole meteorological station with decreasing trend predominant. We detected that there was a belt of becoming drought from northeast to southwest. The contribution of total heavy rainfall to total rainfall as well as long-duration heavy rainfall to total heavy rainfall showed " 展开更多
关键词 Precipitation CONTRIBUTION Spatial DIFFERENCE Long and short-duration HEAVY RAINFALL Total HEAVY RAINFALL China
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Chiral Extrapolation of Lattice Data of Λ_b→Λ_c Form Factors
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作者 李瑞成 郭新恒 《理论物理通讯:英文版》 SCIE CAS CSCD 2019年第2期175-191,共17页
An extrapolation to the physical limit for the lattice data of Λ_b →Λ_c form factors computed in the nonphysical region is made in this work through a class of fitting functions proposed by us with nonlinear depend... An extrapolation to the physical limit for the lattice data of Λ_b →Λ_c form factors computed in the nonphysical region is made in this work through a class of fitting functions proposed by us with nonlinear dependence on m2/π derived in the chiral perturbative theory(ChPT) and the heavy quark effective theory(HQET) framework. Then the results are applied to calculate the differential and integrated Λ_b →Λ_c semileptonic decay rates. Meanwhile, a comparison between our results and those obtained through the extrapolation functions with naive linear dependenceon m2/π is made.It is shown that the difference between the extrapolated central values of these two cases is about 5%.The total uncertainties(depending on the momentum transfer q~2) in the linear case are about 5% ~10%(caused by the uncertainties of lattice data) and those in the nonlinear case are about 10% ~ 20%(caused by the uncertainties of both lattice data and input parameters in Ch PT and HQET). More accurate lattice data and parameters in ChPT and HQET are needed to reduce the uncertainties of the extrapolated results. 展开更多
关键词 HEAVY BARYON form factors LATTICE QCD CHIRAL perturbative THEORY HEAVY quark effective THEORY
Response of Platanus orientalis leaves to urban pollution by heavy metals 预览
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作者 Esmaiel Khosropour Pedram Attarod +4 位作者 Anoushirvan Shirvany Thomas Grant Pypker Vilma Bayramzadeh Leila Hakimi Mazaher Moeinaddini 《林业研究:英文版》 CAS CSCD 2019年第4期1437-1445,共9页
Atmospheric pollution is an important concern in urban environments.The impact of urban pollution on the physiological,biochemical and anatomical properties of leaves of oriental plane(Platanus orientalis L.)was studi... Atmospheric pollution is an important concern in urban environments.The impact of urban pollution on the physiological,biochemical and anatomical properties of leaves of oriental plane(Platanus orientalis L.)was studied.The leaves were collected from an urban site(Tehran,Iran)and a non-urban forest park(Chitgar Forest Park).Anatomical(stomata,parenchyma,and cuticle)and physiological(chlorophyll content,enzyme activities)properties were analyzed.The concentrations of Cd(cadmium),Pb(lead),Ni(nickel),and Cr(chromium)in leaves were significantly higher and Zn(zinc)lower at the urban site relative to the forest park.Chlorophyll a,total chlorophyll,and carotenoid content in leaves of the urban site were significantly less than those of the forest park,but there was no significant difference in chlorophyll b.In addition,the activities of superoxide dismutase,catalase,ascorbate peroxidase,and guaiacol peroxidase in urban leaves were significantly higher than in the leaves of the forest park.In the urban area,leaves experienced a significant decrease in leaf surface area,stomata density,stomata pore area,epidermis,and spongy mesophyll thickness,but a significant increase in cuticle and palisade thicknesses relative to forest park leaves.The increase in enzyme activities may indicate that the trees are attempting to cope with increased reactive oxygen species(ROS)because of pollution-induced stress.Our study suggests that oriental plane trees alter their physiological and anatomical properties when living in a polluted urban environment. 展开更多
关键词 HEAVY metals LEAF ANATOMY LEAF PHYSIOLOGY Atmospheric pollution
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基于Geo-SOM方法的土壤环境调查数据库探索性分析
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作者 廖晓勇 陶欢 +1 位作者 龚雪刚 李尤 《地理学报:英文版》 SCIE CSCD 2019年第10期1610-1624,共15页
A model integrating geo-information and self-organizing map(SOM) for exploring the database of soil environmental surveys was established. The dataset of 5 heavy metals(As, Cd, Cr, Hg, and Pb) was built by the regular... A model integrating geo-information and self-organizing map(SOM) for exploring the database of soil environmental surveys was established. The dataset of 5 heavy metals(As, Cd, Cr, Hg, and Pb) was built by the regular grid sampling in Hechi, Guangxi Zhuang Autonomous Region in southern China. Auxiliary datasets were collected throughout the study area to help interpret the potential causes of pollution. The main findings are as follows:(1) Soil samples of 5 elements exhibited strong variation and high skewness. High pollution risk existed in the case study area, especially Hg and Cd.(2) As and Pb had a similar topological distribution pattern, meaning they behaved similarly in the soil environment. Cr had behaviours in soil different from those of the other 4 elements.(3) From the U-matrix of SOM networks, 3 levels of SEQ were identified, and 11 high risk areas of soil heavy metal-contaminated were found throughout the study area, which were basically near rivers,factories, and ore zones.(4) The variations of contamination index(CI) followed the trend of construction land(1.353)> forestland(1.267)> cropland(1.175)> grassland(1.056), which suggest that decision makers should focus more on the problem of soil pollution surrounding industrial and mining enterprises and farmland. 展开更多
关键词 SELF-ORGANIZING MAP geo-information HEAVY metal soil ENVIRONMENTAL quality Hechi
Heavy Oils and Oil Sands:Global Distribution and Resource Assessment 预览
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作者 LIU Zuodong WANG Hongjun +7 位作者 Graham BLACKBOURN MA Feng HE Zhengjun WEN Zhixing WANG Zhaoming YANG Zi LUAN Tiansi WU Zhenzhen 《地质学报:英文版》 SCIE CAS CSCD 2019年第1期199-212,共14页
Gl obal recoverable resources of heavy oil and oil sands have been assessed by CNPC using a geology-based assessment method combined with the traditional volumetric method,spatial interpolation method,parametric-proba... Gl obal recoverable resources of heavy oil and oil sands have been assessed by CNPC using a geology-based assessment method combined with the traditional volumetric method,spatial interpolation method,parametric-probability method etc.The most favourable areas for exploration have been selected in accordance with a comprehensive scoring system.The results show:(1)For geological resources,CNPC estimate 991.18 billion tonnes of heavy oil and 501.26 billion tonnes of oil sands globally,of which technically recoverable resources of heavy oil and oil sands comprise 126.74 billion tonnes and 64.13 billion tonnes respectively.More than 80%of the resources occur within Tertiary and Cretaceous reservoirs distributed across 69 heavy-oil basins and 32 oil-sands basins.99%of recoverable resources of heavy oil and oil sands occur within foreland basins,passive continental-margin basins and cratonic basins.(2)Since residual hydrocarbon resources remain following large-scale hydrocarbon migration and destruction,heavy oil and oil sands are characterized most commonly by late hydrocarbon accumulation,the same basin types and source-reservoir conditions as for conventional hydrocarbon resources,shallow burial depth and stratabound reservoirs.(3)Three accumulation models are recognised,depending on basin type:degradation along slope;destruction by uplift;and migration along faults.(4)In addition to mature exploration regions such as Canada and Venezuela,the Volga-Ural Basin and the Pre-Caspian Basin are less well-explored and have good potential for oil-sand discoveries,and it is predicted that the Middle East will be an important region for heavy-oil development. 展开更多
关键词 HEAVY OIL OIL SAND RESIDUAL hydrocarbons GLOBAL RESOURCE assessment
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Effect of phosphatation and calcination on the environmentalbehaviour of sediments 预览
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作者 Moussa Dia Rachid Zentar +3 位作者 Nor-edine Abriak Ange Nzihou Guy Depelsenaire Alain Germeau 《国际泥沙研究:英文版》 SCIE 2019年第5期486-495,共10页
Dredging operations produce considerable quantities of materials, to be managed and this opens an opportunity for valorization in civil engineering. However, the contamination of the dredged sediments has become a maj... Dredging operations produce considerable quantities of materials, to be managed and this opens an opportunity for valorization in civil engineering. However, the contamination of the dredged sediments has become a major problem to solve. The major contaminants are heavy metals and organic compounds. This study focuses on the use of phosphoric acid (H3PO4) to stabilize heavy metals from sediments and destroy organic matter by calcination at 650 °C with a goal of using sediments in roadworks. Several studies have been conducted in this eld. The stabilized materials obtained have been used in civil engineering. The main purpose of this work is to discuss the environmental behavior of marine sediment treated by phosphatation and calcination. Two types of phosphoric acids were used. The pH dependence leaching test has been used as the basic characterization to evaluate the effect of the type of phosphoric acid on the metals behavior in a valorization scenario. The standard leaching test and the Toxicity Characteristic Leaching Procedure (TCLP) were conducted as compliance tests. In regards of the obtained results, the environmental assessment has also shown a reduction in the availability of targeted heavy metals in alkaline environment whatever the type of acid used for treatment. This opens opportunities for co-valorization. 展开更多
关键词 Polluted SEDIMENTS HEAVY metals Phosphatation CALCINATION and environmental BEHAVIOUR
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Main Components and Antioxidant Activity of Callisia repens Extracts 预览
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作者 Bo LENG Shaoru CAI +6 位作者 Xiumin LI Jiafu HUANG Yu XUE Zhichao LIN Wensong CHEN Chunxian LI Yutian PAN 《亚洲农业研究:英文版》 2019年第7期76-79,共4页
To study the main active components and antioxidant activity in vitro of extracts from Callisia repens , the contents of main active components such as total flavonoids, total anthocyanin and total sugar in the extrac... To study the main active components and antioxidant activity in vitro of extracts from Callisia repens , the contents of main active components such as total flavonoids, total anthocyanin and total sugar in the extracts were studied by spectrophotometry. The components and content of 18 kinds of metals were determined by ICP-MS mass spectrometry. Finally, the oxidative activity of the extract was evaluated by spectrophotometry. Results showed that the content of flavonoids, the total protein, the total sugar and the total anthocyanin in C. repens extract powder were 2.04%, 1.83%, 55.2% and 7.2%, respectively. Beneficial trace elements such as Ca, Mn, Mg in C. repens extracts were higher, while harmful heavy metals such as Pb, Hg, Ag, Co, Ge were very tiny or not detected at all. The IC 50 of C. repens was 0.265 mg/mL for scavenging DPPH·, and 1.16 mg/mL for scavenging ·OH free radical, the total reducing power of 1 mg extract was equivalent to that of 39 μg of Vc, and the extract showed no regular chelating power to ferrous ions. In conclusion, C. repens extracts have high content of natural active components, but extremely low content of the harmful heavy metals, and C. repens extract has good antioxidant capacity. Its antioxidant activity is realized by a variety of active factors through a synergistic mechanism. Thus, C. repens extract has great potential for developing into functional foods. 展开更多
关键词 Callisia repens ANTIOXIDANT activity TOTAL FLAVONOIDS TOTAL ANTHOCYANIN Heavy metal
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Removal of Toluene by Adsorption/Desorption Using Ultra-stable Y Zeolite 预览
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作者 Lei Xu Yonghong Li +1 位作者 Jiang Zhu Zhiyuan Liu 《天津大学学报:英文版》 EI CAS 2019年第4期312-321,共10页
The adsorption performance of toluene on ultra-stable Y zeolite (USY) was studied via dynamic adsorption. The eff ects of bed temperature, initial concentration, and feed fl ow rate on adsorption were investigated. Th... The adsorption performance of toluene on ultra-stable Y zeolite (USY) was studied via dynamic adsorption. The eff ects of bed temperature, initial concentration, and feed fl ow rate on adsorption were investigated. The Yoon-Nelson model was used to fi t the toluene breakthrough curves. The length of mass transfer zone was calculated based on breakthrough curves. The Langmuir-Freundlich model fi t the adsorption isotherms of toluene on USY, which indicated that the surface of USY was heterogeneous. The adsorption isosteric heat calculated from adsorption isotherms ranged from 54.3 to 69.8 kJ/mol, indicating physical adsorption. The combined technique of temperature swing adsorption with vacuum swing adsorption (TVSA) exhibited excellent desorption performance, which was attributed to the low desorption activation energy. Under optimized TVSA conditions, the desorption rate of toluene reached 90.6% within 10 min. The long-term cyclic utilization results indicated that the adsorption capacity of USY was stable. 展开更多
关键词 Adsorption DESORPTION USY TOLUENE HEAVY VOC
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An overview of carbon nanotubes role in heavy metals removal from wastewater
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作者 Leila Ouni Ali Ramazani Saeid Taghavi Fardood 《化学科学与工程前沿:英文版》 EI CAS CSCD 2019年第2期274-295,共22页
The scarcity of water, mainly in arid and semiarid areas of the world is exerting exceptional pressure on sources and necessitates offering satisfactory water for human and different uses. Water recycle/reuse has conf... The scarcity of water, mainly in arid and semiarid areas of the world is exerting exceptional pressure on sources and necessitates offering satisfactory water for human and different uses. Water recycle/reuse has confirmed to be successful and promising in reliable water delivery. For that reason, attention is being paid to the effective treatment of alternative resources of water (other than fresh water) which includes seawater, storm water, wastewater (e.g., dealt with sewage water), and industrial wastewater. Carbon nanotubes (CNTs) are called the technology of 21st century. Nowadays CNTs have been widely used for adsorption of heavy metals from water/ wastewater due to their unique physical and chemical properties. This paper reviews some recent progress (from 2013 to 2018) in the application of CNTs for the adsorption of heavy metals in order to remove toxic pollutants from contaminated water. CNTs are expected to be a promising adsorbent in the future because of its high adsorption potential in comparison to many traditional adsorbents. 展开更多
关键词 carbon NANOTUBES HEAVY METALS removal water treatment
Does Rapid Urbanization Trigger Significant Increase of Cumulative Heavy Rains in China? 预览
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作者 Feng KONG 《亚洲农业研究:英文版》 2019年第6期25-32,共8页
Severe disasters caused by extreme precipitation events have attracted more and more attention. The relationship between climate change and extreme precipitation has become the hottest scientific frontier issue. The s... Severe disasters caused by extreme precipitation events have attracted more and more attention. The relationship between climate change and extreme precipitation has become the hottest scientific frontier issue. The study of daily torrential rain observations from 659 meteorological stations in China from 1951 to 2010 shows that rapid urbanization may have triggered a significant increase in heavy rains in China. It reached following conclusions: China’s interdecadal heavy rainfall amount,rainy days and rain intensity increased significantly,with an increase of 68. 71%,60. 15% and 11. 52%,respectively. The increase in the number of stations was 84. 22%,84. 22% and 54. 48%,respectively. It showed time change of " rapid-slow-rapid increase" and spatial change of gradual increase from southeastern coast to central China,southwest,north China,and northeastern regions. Rapid urbanization factors,including secondary industry output( GDP2),urban population ratio( UP),annual average haze days( HD),are likely to be the main causes of the increase in heavy rains in China. Their explanations of the variance of heavy rainfall amount( HRA),rainy day( RD) and rain intensity( RI) in China reached 61. 54%,58. 48% and 65. 54%,respectively,of which only the explanation of variance of heavy rainfall amount,rainy days and rain intensity was as high as 25. 93%,22. 98%and 26. 64%,respectively. However,explanation of variance of climatic factors including WPSH( West Pacific Subtropical High),ENSO( El Ni1 o-Southern Oscillation) AMO( Atlantic Interdecadal Oscillation),and AAO( Antarctic Oscillation) was only 24. 30%,26. 23%,and 21. 92%,respectively. Compared with the rapid urbanization forcing factor,the impact of these climatic factors was only one third of the former. The panel data of China’s county-level total population and annual average of visibility days were significantly correlated with China’s interdecadal heavy rainfall amount,rainy days and rain intensity. Their spatial correlation coefficient increased gradually from 展开更多
关键词 CUMULATIVE heavy RAIN Human activities URBANIZATION TRIGGERING factors Spatial and temporal pattern China
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Heavy Metal Pollution and Ecological Risk Assessment in Sediments of Xiling Channel Inland Waterway of Guangdong Province 预览
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作者 Jianqiao QIN Xiaoping HUANG 《亚洲农业研究:英文版》 2019年第6期40-46,49共8页
Using the sediment monitoring data of five sections of the Xiling Channel inland waterway of the Pearl River Delta,and using Nemerow composite index,the coefficient of variation,and the index of geoaccumulation( Igeo)... Using the sediment monitoring data of five sections of the Xiling Channel inland waterway of the Pearl River Delta,and using Nemerow composite index,the coefficient of variation,and the index of geoaccumulation( Igeo) and the potential ecological risk index,this paper analyzed and assessed the heavy metal pollution of sediments. The results indicate that Cr reached mild pollution;Cu had a large degree of variation,and the changes of Cr and Zn were significant with fluctuation;the enrichment of heavy metals decreased as follows: Cd > Cu > Cr > Zn> Pb > Ni > Hg > As;Cd had the highest degree of enrichment and belonged to moderate pollution;the ecological hazard of heavy metals was Cd > Hg > Cu > Pb > As > Cr > Ni > Zn,and Cd had the highest ecological hazard and was the main controlling factor of potential ecological risk. In conclusion,the sediments in Xiling Channel inland waterway were polluted by heavy metals to some extent,and cadmium was the main pollutant and had the largest potential ecological risk. 展开更多
关键词 Xiling CHANNEL INLAND WATERWAY Sediment HEAVY metal pollution
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Rise of the Machines
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作者 Xia Yuanyuan 《中国与非洲:英文版》 2019年第7期26-27,共2页
When it comes to excavating machines, Joseph Garba knows them inside out. Having worked in the business for many years, the Nigerian excavator operator currently digs out soil at the Great Wall Quarry in Abuja. He exp... When it comes to excavating machines, Joseph Garba knows them inside out. Having worked in the business for many years, the Nigerian excavator operator currently digs out soil at the Great Wall Quarry in Abuja. He expertly handles an SY335 machine, produced by Sany Heavy Industry Co. in China, like he could do it blindfolded. 展开更多
关键词 Sany HEAVY INDUSTRY EXCAVATOR
华南某电子垃圾拆解区周边住宅室内灰尘重金属对儿童的非致癌健康风险评估
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作者 陈希超 朱晓辉 +4 位作者 林必桂 李良忠 于紫玲 向明灯 于云江 《中华预防医学杂志》 CAS CSCD 北大核心 2019年第4期360-364,共5页
目的评估华南某电子垃圾拆解区周边住宅室内灰尘重金属对儿童的非致癌健康风险。方法2016年10月,选取中国华南地区某电子垃圾拆解区周边A村作为研究场所,采用方便抽样抽取村庄内的36户住宅,利用真空吸尘器采集样品,共采集36份,测定每份... 目的评估华南某电子垃圾拆解区周边住宅室内灰尘重金属对儿童的非致癌健康风险。方法2016年10月,选取中国华南地区某电子垃圾拆解区周边A村作为研究场所,采用方便抽样抽取村庄内的36户住宅,利用真空吸尘器采集样品,共采集36份,测定每份样品中重金属As、Cd、Cr、Cu、Mn、Pb和Zn的浓度,并计算平均浓度值。分别采用美国环保署(EPA)推荐健康风险评估模型(HRA)、美国毒物与疾病登记署(ATSDR)的靶器官毒性剂量法(TTD)和二元证据权重分析(BINWOE)模型,评估室内灰尘中重金属对当地儿童的非致癌健康风险。结果As、Cd、Cr、Cu、Mn、Pb和Zn的浓度值分别为(48.90±33.91)、(5.95±3.89)、(173.57±580.37)、(412.71±1190.00)、(612.82±540.70)、(297.41±293.22)和(1052.81±1156.48)mg/kg,采用TTD和BINWOE模型得出的叠加风险(HI)值分别为2.670和2.933,分别是HRA模型叠加HI值(1.386)的1.93和2.12倍,均大于EPA推荐非致癌健康风险阈值(1.00)。结论华南某电子垃圾拆解区周边住宅室内灰尘重金属对当地儿童健康存在一定威胁。 展开更多
关键词 空气污染 室内 金属 危险性评估 靶器官毒性剂量 二元证据权重分析
In situ preparation of well-dispersed CuO nanocatalysts in heavy oil for catalytic aquathermolysis
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作者 Ming Chen Chen Li +2 位作者 Guo-Rui Li Yan-Ling Chen Cheng-Gang Zhou 《石油科学:英文版》 SCIE CAS CSCD 2019年第2期439-446,共8页
We developed an in situ synthesis strategy for preparing well-dispersed CuO nanoparticles as aquathermolysis catalyst for viscosity reduction in Shengli heavy oil(China). A Cu(OH)2-contained microemulsion was employed... We developed an in situ synthesis strategy for preparing well-dispersed CuO nanoparticles as aquathermolysis catalyst for viscosity reduction in Shengli heavy oil(China). A Cu(OH)2-contained microemulsion was employed as a carrier to disperse the precursor Cu(OH)2 to the heavy oil phase. Under aquathermolysis condition(240 ℃, 2.5 MPa of N2), the Cu(OH)2 precursors would first be converted in situ to well-crystallized and size-homogeneous CuO nanoparticles naturally, catalyzed by which the viscosity of Shengli heavy oil could be reduced as much as 94.6%;simultaneously, 22.4% of asphaltenes were converted to light components. The agglomeration of the in situ prepared monoclinic CuO nanoparticles could be negligible throughout the catalytic reaction. Based on the characterization results of 1 H NMR, elemental analysis and GC-MS of oil samples before and after catalytic aquathermolysis, the mechanism for viscosity reduction of heavy oil in the catalytic system was investigated. 展开更多
关键词 Cu(OH)2-contained microemulsion In situ preparation CUO NANOCATALYST CATALYTIC viscosity reduction Heavy oil
Vertical physicochemical parameter distributions and health risk assessment for trace metals in water columns in eastern Lake Tanganyika,Tanzania 预览
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作者 SHEN Qiushi ZHANG Lu +4 位作者 Ismael Aaron KIMIREI WANG Zhaode GAO Qun CHEN Shuang YU Cheng 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第1期134-145,共12页
The vertical distributions of trace metals and physicochemical parameters in water columns in Kigoma Bay and Kungwe Bay in eastern Lake Tanganyika,Tanzania,were studied.The Al,Ba,Ca,Co,K,Mg,Mn,Mo,Na,Sn,Sr,and V concen... The vertical distributions of trace metals and physicochemical parameters in water columns in Kigoma Bay and Kungwe Bay in eastern Lake Tanganyika,Tanzania,were studied.The Al,Ba,Ca,Co,K,Mg,Mn,Mo,Na,Sn,Sr,and V concentrations were low and varied very little with depth.The toxic heavy metal(As,Cr,Cu,Ni,Pb,and Zn)concentrations were relatively high in the surface water,and the Cu,Ni,Pb,and Zn concentrations decreased with depth.Principal component and cluster analyses indicated that the metals in the lake had three main sources.Al,Ba,Ca,Co,Cu,Cr,Mn,Sr,Sn,and V were found to be geogenic;As,Cr,Cu,Mo,Ni,Pb,Sn and Zn anthropogenic;and As,Ca,Co,Mg,and Na biogenic.Human health risk assessments were performed,and it was found that trace metals in the water at most of the sampling sites would cause no potential adverse effects or non-carcinogenic health risks through dermal contact or ingestion.However,trace metals in surface water in Kungwe Bay could have certain adverse effects on human health through the ingestion pathway(the total hazard quotient for ingestion(ΣHQ ing)was 1.75(a value >1 was defined as possibly indicating adverse effects).The Pb HQ ing for surface water in Kungwe Bay was 1.50 and contributed >80%of theΣHQ ing,implying that Pb pollution is a water quality and safety problem that needs to be carefully monitored and the potential sources identified. 展开更多
关键词 trace METAL heavy METAL risk assessment water COLUMN Lake TANGANYIKA
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Evaluation of Heavy Metals Concentrations in Oreochromis niloticus and Clarias gariepinus from River and Aquaculture Systems within Owerri Metropolis,Imo State Nigeria 预览
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作者 A.P.Onyena J.U.Udensi 《食品科学与工程:英文版(美国)》 2019年第4期131-138,共8页
People tend to rely upon fish as a source of cheap animal protein and a vital resource to sustain life.Oreochromis niloticus(tilapia fish)and Clarias gariepinus(cat fish)were collected from two rivers(Nworie and Otami... People tend to rely upon fish as a source of cheap animal protein and a vital resource to sustain life.Oreochromis niloticus(tilapia fish)and Clarias gariepinus(cat fish)were collected from two rivers(Nworie and Otamiri rivers)and two fish ponds(FUTO and Philip’s fish ponds in Owerri municipal).The heavy metals analyzed were mercury(Hg),cadmium(Cd),iron(Fe),nickel(Ni),zinc(Zn),lead(Pb),and chromium(Cr)using FS 240 Varianatomic absorption spectrophotometer(AAS)SpectrAA.Catfish accumulated high level of Hg concentrations(>1.40 ppm)in the sample sites,Cd concentration was also high in cat fish(8.33 ppm)sampled from Nworie river while the other sample sites recorded<1 ppm.Also,Fe recorded concentrations above 4 ppm with highest concentration of 30.8 ppm;however,tilapia fish accumulated more Fe concentrations than the cat fish.Heavy metals values in the fishes were above the maximum permissible limits of established standards for fish consumption.Data collected were subjected to t-test and analysis of variance(ANOVA),and there was no statistical difference(p>0.05)between the heavy metals contents of fishes from the rivers and fish ponds studied.The total heavy metals concentrations studied accumulated from the different sample sites were in this order:tilapia fish:Nworie river(5.96±4.36)>Otamiri river(4.87±3.32)>Philip’s pond(4.87±3.19)>FUTO pond(1.62±1.40)while in cat fish:Nworie river(4.02±1.66)>Philip’s pond(3.60±2.10)>Otamiri river(2.43±1.54)>FUTO pond(2.27±1.38).There is need for periodic monitoring and assessment of heavy metals in water bodies and various aquatic lives that serve as a source of food to human. 展开更多
关键词 Heavy metals AQUACULTURE system RIVERS SPECTROPHOTOMETER BIOACCUMULATION fish pollution
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A Comparative Study on Pb Tolerance and Enrichment Characteristics among Different Species of Compositae 预览
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作者 Xuan Bin Wang Ji +4 位作者 Zhang Lingyun Cai Xiongfei Hu Fengqing Duan Zhibin Li Ding 《气象与环境研究:英文版》 CAS 2019年第2期73-77,共5页
In order to find landscape plants purifying Pb pollution of soil,a pot experiment was conducted to study Pb resistance and enrichment characteristics of six species of Compositae plants( Aster ageratoides,Rudbeckia hi... In order to find landscape plants purifying Pb pollution of soil,a pot experiment was conducted to study Pb resistance and enrichment characteristics of six species of Compositae plants( Aster ageratoides,Rudbeckia hirta,Cosmos sulphureus,Gynura bicolor,Calendula officinalis,Bidens pilosa) in different soil Pb concentrations. The results showed that the dry weight of aboveground part in the six plants decreased with the increase of soil Pb concentration. The tolerance index( TI) of C. sulphureus,G. bicolor and C. officinalis was greater than 0. 5 in all concentrations,and the root tolerance index( RTI) was greater than 0. 9,which were better resistant to Pb stress. The maximum Pb content in aboveground part of R. hirta was 1 783 mg/kg,and the enrichment and transport coefficients were all greater than 1. When the soil Pb concentration was 500 mg/kg,the total Pb accumulation in the aboveground part of R. hirta was 2. 507 mg/plant. Finally based on the integrated observation of the enrichment coefficient,transport factor and repair potential index,it believed that R. hirta can be used to restore Pb contaminated soil at low concentration. 展开更多
关键词 HEAVY metal COMPOSITAE Pb TOLERANCE ENRICHMENT CHARACTERISTICS
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Combined Fenton process and sulfide precipitation for removal of heavy metals from industrial wastewater:Bench and pilot scale studies focusing on in-depth thallium removal
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作者 Huosheng Li Hongguo Zhang +2 位作者 Jianyou Long Ping Zhang Yongheng Chen 《环境科学与工程前沿(英文)》 SCIE EI CAS CSCD 2019年第4期23-34,共12页
Thallium (Tl) in industrial wastewater is a public health concern due to its extremely high toxicity. However, there has been limited research regarding Tl removal techniques and engineering practices to date. In this... Thallium (Tl) in industrial wastewater is a public health concern due to its extremely high toxicity. However, there has been limited research regarding Tl removal techniques and engineering practices to date. In this investigation, bench and pilot studies on advanced treatment of industrial wastewater to remove Tl to a trace level were conducted. The treatment process involved a combination of hydroxide precipitation, Fenton oxidation, and sulfide precipitation. While hydroxide precipitation was ineffective for Tl^+ removal, it enabled the recovery of approximately 70%-80% of Zn as Zn hydroxide in alkaline conditions. The Fenton process provided good Tl removal (>95%) through oxidation and precipitation. Tl was then removed to trace levels (< 1.0 μg/L) via sulfide precipitation. Effective removal of other heavy metals was also achieved, with Cd < 13.4 μg/L, Cu < 39.6 μg/L, Pb < 5.32 μg/L, and Zn < 357 μg/L detected in the effluent. X-ray photoelectron spectroscopy indicated that T12S precipitate formed due to sulfide precipitation. Other heavy metals were removed via the formation of metal hydroxides during hydroxide precipitation and Fenton treatment, as well as via the formation of metal sulfides during sulfide precipitation. This combined process provides a scalable approach for the in-depth removal of Tl and other heavy metals from industrial wastewater. 展开更多
关键词 THALLIUM Pilot FENTON SULFIDE precipitation Heavy metal Industrial wastewater
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