检索结果-南通市图书馆

partitioning of water soluble organic carbon in three sediment size fractions:Effect of the humic substances

Journal of Environmental Sciences 2009年第1期21卷 113-119页

作者： SUN Liying Department of Environmental Engineering Peking University Beijing 100871 China. Key Laboratory of Water and Sediment Sciences Ministry of Education of China Beijing 100871 China

Water soluble organic carbon （WSOC） in sediments plays an important role in transference and transformation of aquatic pollutants. This article investigated the inherent mechanisms of how sediemnt grain size affect the partitioning coeffcient （k） of WSOC. Influences of NaOH extracted humic substances were particularly focused on. Sediments were sampled from two cross-sections of the middle Yellow River and sieved into three size fractions （〈 63 μm, 63-100 μm, and 100-300 μm）. The total concentration of WSOC in sediments （Cwsoc） and k were estimated using multiple water-sediment ratio experiments. Results showed that Cwsoc ranged from 0.012 to 0.022 mg/g, while k ranged from 0.8 to 3.9 L/kg. Correlations between the spectrum characteristics of NaOH extracted humic substances and k were analyzed. Strong positive correlations are determined between k and the aromaticity indicators of NaOH extracted humic substances in different sediment size fractions. Comparing with finer fractions （〈 63 μm）, k is higher in larger size fractions （63- 100 μm and 100-300 μm） related to higher aromaticity degree of NaOH extracted humic substances mostly. While negative relationship between k and the area ratio of fourier transform infrared spectroscopy （FT-IR） at 3400 and 1430 cm^-1 implied that the lowest k was related to the highest concentration of acidic humic groups in particles 〈 63 μm. WSOC in finer fractions （〈 63 μm） is likely to enter into pore water, which may further accelerate the transportation of aquatic contaminants from sediment to water.

关键词： humic substances water soluble organic carbon partitioning sediment

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

partitioning of heavy metals in the surface sediments of Quanzhou Bay wetland and its availability to Suaeda australis

引用

Journal of Environmental Sciences 2006年第2期18卷 334-340页

作者： LI Yu-hong YAN Chong-ling YUAN Jian-jun LIU Jing-chun CHEN Huai-yu HU Jun School of Life Sciences Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China iology Department of Quanzhou Normal College Quanzhou 362000 China

In order to investigate distributions of heavy metal pollution in Quanzhou Bay wetland, the total concentration and chemical partitioning of a number of heavy metals （Cu, Zn, Cd, Pb, Cr, Hg） in sediments of three sampling sites of Quanzhou Bay wetland and their availability to Suaeda australis were analyzed. The Geoaccumulation Index （Igeo） values reveal that the sediments of three sampling sites may all be considered as moderately contaminated for Pb and Zn, and all sediments might be strongly contaminated with cadmium. The partitioning analyses revealed the measured heavy metals in three sites are bound to the exchangeable fraction at lower concentrations. The measured metals in a considerable amount are bound to the reducible and oxidizable fractions, and a high proportion of the measured heavy metals were distributed in the residual fraction in the sediment samples. The concentrations of Cd in each chemical phase extracted from the sediments are above natural global background levels and should be further investigated because of its toxicity. Suaeda australis has different accumulation abilities for the measured heavy metals. For the root and stem, the bioaccumulation ability assessed by bioaccumulation factor （BAF） for the measured heavy metals follows the decreasing order as： Cu〉Cr〉 Zn〉Cd, Pb, Hg. In the leaf, stronger bioaccumulation ability for Hg is exhibited. The heavy metal concentrations in Suaeda australis roots have positive correlations with their available fractions, while the exchangeable fraction of Cu and Cd might have be more important to both mature plant roots and seedling roots uptake than other fractions; as for Cr, the oxidizable fraction might make a greater contribution to the plant root uptake; as for Zn, the reducible fraction might make so contribution ; and for Pb, the oxidizable fraction might make a significant contribution to the mature plant root uptake, however, the exchangeable fraction might have a significant contribution to th

关键词： bioavailability geoaccumulation factor partitioning heavy metals Suaeda australis sediment Quanzhou Bay wetland

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

partitioning properties of rare earth ores in China

引用

Rare Metals 2005年第3期24卷 205-209页

作者： CHI Ru ＇an LI Zhongjun PENG Cui ZHU Guocai XU Shengming Hubei Key Laboratory of Chemical Reactor and Green Chemical Technology Wuhan Institute of Chemical Technology Wuhan 430074 China Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China

The properties of rare earth partitioning in Chinese industrial rare earth ores were analyzed. Rare earth ores can be divided into the single-mineral type ore with bastnaesite, the multi-mineral type ore with bastnaesite and monazite, and the weathering crust type. Both the Bayan Obo rate earth ore and the Zhushan rate earth ore are a kind of mixed ore, consisting of basmaesite and monazite. Their rate earth partifionings are strongly enriched in light rate earths, where CeO2 is 50% and the light rate earth partitioning is totally over 95%. The Mianning rate earth ore as well as the Weishan rate earth is a kind of rate earth ore only having basmaesite. Their rare earth partitionings are also strongly enriched in light rate earths, in which CeO2 is 47% and the light rare earth partitioning is totally over 94%. For the weathering crust type rate earth ore, there are the Longnan rare earth ore, the Xunwu rare earth ore, and the middle yttrium and rich europium ore. In the Longnan rate earth ore, which is strongly enriched in heavy rate earths, Y2O3 is 64.83%, and the heavy and light rate earth partitionings are 89.40% and 10.53%, respectively. In the Xunwu rate earth ore, which is strongly enriched in light rate earths, CeO2 is 47.16%, and the light rate earth partitioning is totally 93.25%. Y and Eu are enriched in the middle yttrium and rich europium ore. Its middle rare earth partitioning is totally over 10%, and Eu2O3 and Y2O3 are over 0.5% and 20%, respectively, which are mainly industrial resources of the middle and the heavy rare earths.

关键词： rare earth ore partitioning bastnaesite monazite weathered crust ore

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Polybrominated diphenyl ethers in atmosphere and soil of a production area in China:Levels and partitioning

引用

Journal of Environmental Sciences 2011年第3期23卷 427-433页

作者： Jun Jin Ying Wang Weizhi Liu Congqiao Yang Jicheng Hu Jian Cui College of Life and Environmental Sciences Minzu University of China Beijing 100081 China Chinese Minority Tradition Medicine Center Minzu University of China Beijing 100081 China

Polybrominated diphenyl ethers （PBDEs） were measured in atmosphere and soil samples taken in winter and summer at a PBDE production area of Laizhou Bay in China. The concentrations of ∑11PBDE were 0.017-1.17 ng/m3 in gaseous phase, 0.5-161.1 ng/m3 in particulate phase, and 73-2629 ng/g dry weight in soil samples. The PBDE congener pattern in the gaseous phase differed from that in the particulate phase, and the PBDE congener pattern in the particulate phase was similar with that in soil. This demonstrated that there was little difference with atmospheric particle-soil transfer efficiency among PBDE congeners. In addition, there were seasonal variations in percentages on particle for lower brominated congeners. The BDE-28 was mostly in the gaseous phase in summer （88.3%）, whereas the average proportion of BDE-28 in gaseous phase in winter was 38.9%. Higher brominated congeners （i.e., BDE-206, BDE- 207, BDE-208, and BDE-209） were bound to the atmospheric particulate phase, and their potentials for long-range migration were mainly affected by the environmental behavior of atmospheric particles. Results indicated that PBDE congeners in summer were closer to gas-particle partition equilibrium than in winter. Temperature should be considered the main factor causing nonequilibrium in winter.

关键词： polybrominated diphenyl ethers atmosphere soil partitioning production area

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Kinetic and thermodynamic studies on partitioning of polychlorinated biphenyls (PCBs) between aqueous solution and modeled individual soil particle grain sizes

引用

Journal of Environmental Sciences 2019年第2期31卷 100-110页

作者： Gbadebo Clement Adeyinka Brenda Moodley School of Chemistry and Physics College of AgricultureEngineering and SciencesUniversity of KwaZulu-Natal

The significance of soil mineral properties and secondary environmental conditions such as pH, temperature, ionic strength and time in the partitioning of eight selected polychlorinated biphenyl(PCB) congeners between aqueous solution and soil particles with different grain sizes was studied. The mineral properties of a model soil sample were determined, and Brunauer–Emmett–Teller(BET) adsorption–desorption isotherms were employed to observe the surface characteristics of the individual modeled soil *** adsorption experiments were conducted to determine the sorption of PCBs onto soil particles of different sizes. The results revealed that the sorption of PCB congeners onto the soil was dependent on the amount of soil organic matter, surface area, and pore size distribution of the various individual soil particles. Low pH favored the sorption of PCBs,with maximum sorption occurring between pH 6.5 and 7.5 with an equilibration period of 8 *** in the ionic strength were found to be less significant. Low temperature favored the sorption of PCBs onto the soil compared to high temperatures. Thermodynamic studies showed that the partition coefficient(K_d) decreased with increasing temperature, and negative and low values of ΔH° indicated an exothermic physisorption process. The data generated is critical and will help in further understanding remediation and cleanup strategies for polluted water.

关键词： partitioning PCBs Soil particle grain sizes Kinetics Thermodynamic studies pH

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Element distribution and difusion behavior in Q&P steel during partitioning

引用

International Journal of Minerals,Metallurgy and Materials 2013年第11期20卷 1050-1059页

作者： Hai-tao Jiang Bao-tong Zhuang Xiao-ge Duan Yan-xin Wu Zheng-xu Cai National Engineering Research Center for Advanced Rolling Technology University of Science and Technology Beijing

Carbon, manganese, and silicon distribution in quenching and partitioning （Q＆P） steel during partitioning process was investigated to reveal the diffusion behavior. The microstructure and chemical composition were analyzed by means of scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and three-dimensional atom probe. It is shown that the studied Q＆P steel consisted of martensite laths and thin, film-like retained austenite showing extraordinary phase transformation stability. Carbon atoms mostly diffused to the retained austenite from martensite at a higher partitioning temperature. In the experimental steel partitioned at 400℃ for 10-60 s, carbides or cementite formed through carbon segregation along martensite boundaries or within the martensite matrix. As a result of carbon atom diffusion from martensite to austenite, the carbon content in martensite could be ignored. When the partitioning process completed, the constrained carbon equilibrium （CCE） could be simplified. Results calculated by the simplified CCE model were similar to those of CCE, and the difference between the two optimum quenching temperatures, where the maximum volume fraction of the retained austenite can be obtained by the Q＆P process, was little.

关键词： steel heat treatment quenching partitioning element distribution diffusion microstructure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

partitioning regularity of nonionic organic mixtures in organic phase/water system

引用

Chinese Science Bulletin 2001年第17期46卷 1422-1425页

作者： Lin, ZF Yu, HX Huang, LM Feng, JF Wang, LS Nanjing Univ Sch Environm State Key Lab Pollut Control & Resources Reuse Nanjing 210093 Peoples R China

The partitioning regularity of nonionic organic mixtures in organic phase/water system is revealed. The equation for calculating the partition coefficients of mixtures (KMD), together with the determination model, is derived from the equilibrium partitioning models (EPMs). Based on these derived equations, the KMD values of 20 mixtures containing halogenated benzenes are obtained. The results show that stronger hydrophobidty of an individual chemical in the mixture results in the stronger hydrophobidty of the mixture and the greater the proportion of this chemical, the stronger the hydrophobidty of the mixture will be. This partitioning regularity is helpful to the study of the toxicity for mixtures and the environmental behavior, such as transfer or accumulation, for mixed organic pollutants.

关键词： mixed organic pollutants the partitioning regularity of mixtures equilibrium partitioning model Cu-EmporeTM disks/water partition coefficient.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Excellent mechanical properties and resistance to cavitation erosion for an ultra-low carbon Cr Mn N stainless steel through quenching and partitioning treatment

引用

International Journal of Minerals,Metallurgy and Materials 2018年第5期25卷 547-553页

作者： Ze-an Zhou Wan-tang Fu Zhe Zhu Bin Li Zhong-ping Shi Shu-hua Sun State Key Laboratory of Metastable Materials Science and Technology Yanshan University

The retained austenite content(RAC),the mechanical properties,and the resistance to cavitation erosion(CE)of the00Cr13Mn8Mo N steel after quenching and partitioning(Q&P)processing were *** results show that the Q&P process affected the RAC,which reached the maximum value after partitioning at 400°C for 10 *** tensile strength of the steel slightly decreased with increasing partitioning temperature and ***,the elongation and product of strength and elongation first increased and then *** sample partitioned at 400°C for 10 min exhibited the optimal property:a strength-ductility of 23.8 GPa?%.The resistance to CE for the 00Cr13Mn8Mo N steel treated by the Q&P process was improved due to work hardening,spalling,and cavitation-induced martensitic transformation of the retained austenite.

关键词： CrMnN steel quenching and partitioning process retained austenite mechanical property cavitation erosion

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Parameters optimization design of quenching and partitioning for best combination between strength and ductility using orthogonal experimental design

引用

Journal of Iron and Steel Research International 2019年第10期26卷 1088-1095页

作者： Ming-qing Liao Zhong-hong Lai Aorigele Bao Yong Liu Dan-ni Yang Tian-yi Han Jing-chuan Zhu Rong-da Zhao School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001HeilongjiangChina The Center of Analysis Measurement Harbin Institute of TechnologyHarbin 150001HeilongjiangChina National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001HeilongjiangChina School of Materi

Quenching and partitioning(Q&P)which provides a balance between toughness and strength is a promising heat treatment in iron and steel ***,there are three parameters(quenching temperature,partitioning temperature and partitioning time)which affect the properties *** a result,it remains a challenge to get the best parameters in a low-cost way for Q&P ***,the orthogonal experimental design combined with a local optimization was adopted to optimize the quenching and partitioning parameters of 65Si2MnWA *** using this method,the combination between strength and ductility was optimized;meanwhile,the number of experiments was reduced *** treated by quenching at 180℃followed by partitioning at 330℃for 20 min,the steel reached the best combination between strength and *** detail,the product of ultimate tensile strength and reduction in area was 1.36 times(from 64.9 to 88.8 GPa%)that treated by quenching and *** addition,owing to the grain refinement,the strength and ductility increase ***,the reduction in area increased by 27.4%(from 35.8%to 45.6%)coupled with a little improvement in ultimate tensile strength(7.4%).

关键词： Parameter optimization design Quenching and partitioning Orthogonal experimental design Mechanical property 65Si2MnWA steel

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Effect of lower bainite/martensite/retained austenite triplex microstructure on the mechanical properties of a low-carbon steel with quenching and partitioning process

引用

International Journal of Minerals,Metallurgy and Materials 2016年第3期23卷 303-313页

作者： Wan-song Li Hong-ye Gao Zhong-yi Li Hideharu Nakashima Satoshi Hata Wen-huai Tian School of Materials Science and Engineering University of Science and Technology Beijing Interdisciplinary Graduate School of Engineering Sciences Kyushu University

We present a study concerning Fe-0. 176C-1.31Si-1.58Mn-0.26Al-0.3Cr （wt%） steel subjected to a quenching and partitioning （Q＆P） process. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and tensile tests demon- strate that the microstructures primarily consist of lath martensite, retained austenite, lower bainite （LB）, and a small amount of tempered martensite; moreover, few twin austenite grains were observed. In the microstrucmre, three types of retained austenite with different sizes and morphologies were observed： blocky retained austenite （-300 nm in width）, film-like retained austenite （80-120 nm in width）, and ul- tra-fine film-like retained austenite （30-40 nm in width）. Because of the effect of the retained austenite/martensite/LB triplex microstructure, the specimens prepared using different quenching temperatures exhibit high ultimate tensile strength and yield strength. Furthermore, the strength effect of LB can partially counteract the decreasing strength effect of martensite. The formation of LB substantially reduces the amount of retained austenite. Analyses of the retained austenite and the amount of blocky retained austenite indicated that the carbon content is critical to the total elongation of Q＆P steel.

关键词： low-carbon steel quenching partitioning retained austenite rnicrostructure mechanical properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：