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A comparison between high temperature catalytic and persulfate oxidation for the determination of total dissolved nitrogen in natural waters
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作者 Tiantian Ge Xue Yang +1 位作者 Shan Jiang Liju Tan 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第4期41-49,共9页
Total dissolved nitrogen(TDN) is an important parameter for assessing the nutrient cycling and status of natural waters.The accurate determination of TDN in natural waters is essential for assessing its contents and d... Total dissolved nitrogen(TDN) is an important parameter for assessing the nutrient cycling and status of natural waters.The accurate determination of TDN in natural waters is essential for assessing its contents and distinguishing different forms of nitrogen in the water.The TDN in various systems has been largely documented,and the concentrations of TDN are usually obtained using high-temperature catalytic(HTC) or persulfate oxidation(PO).However,the accuracy of these methods and their suitability for all types of natural waters are still unclear.To explore both methods in-depth,assorted samples were tested,including eight solutions composed of nitrogen-containing compounds(3 dissolved inorganic nitrogen fractions:NO_(3)^(-),NO_(2)^(-)and NH_(4)^(+);5 organic compounds:EDTA-2Na,vitamin B1,vitamin B12,amino acids,and urea) and 105 natural waters which were collected from an open ocean(Northwest Pacific Ocean,28),a marginal sea(Yellow Sea,34),an estuary(Huanghe River mouth,31),rivers(Huanghe River,4;Licun River,4),and precipitations(4 samples).The results showed that heterocycles and molecular dimensions had certain effects on the oxidation efficiency of the PO method but had little effect on HTC.There was no significant difference between the two methods for natural waters,but HTC was more suitable for deep-sea samples with low TDN concentrations(less than 10 μmol/L) and low organic activity.Overall,HTC has a relatively simple measurement process,a high degree of automation,and low error.Therefore,HTC can be recommended to determine the TDN of samples in freshwater and seawater. 展开更多
关键词 total dissolved nitrogen high-temperature catalytic persulfate oxidation natural waters
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Adsorption of Pb, Cd to Fe, Mn oxides in natural freshwater surface coatings developed in different seasons 被引量:7
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作者 DONGDe-ming YANGFan LIYu HUAXiu-yi LüXiao-jun ZHANGJing-jing 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2005年第1期30-36,共7页
Metal oxides(Fe, Mn oxides) in natural surface coatings(biofilms and associated minerals) are believed to play a significant role in the fate and transport of trace metal in aquatic environments. Seasonal variation of... Metal oxides(Fe, Mn oxides) in natural surface coatings(biofilms and associated minerals) are believed to play a significant role in the fate and transport of trace metal in aquatic environments. Seasonal variation of Fe, Mn oxides and organic materials in surface coatings, which were developed periodically on glass slides in Nanhu Lake, Jilin Province, China over the time frame of three seasons, was investigated in order to understand the influence of metal oxides on Pb and Cd adsorption to heterogeneous surface coating materials(biofilm). Pb and Cd adsorption was measured under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0 05 mol/L, 25℃ and pH 6 0). The classical Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb and Cd adsorption to the surface coatings. In general, components in the surface coatings varied greatly with seasons altering and obtained higher concentrations in summer while the content of iron oxides always exceeded that of manganese oxides. Correlation analyses between the maximum adsorption of Pb and Cd and components in the surface coatings developed periodically indicated that Pb phase association with Mn oxides and Cd phase association with Fe oxides as well as Mn oxides were statistically significant. Effect of Mn oxides on Cd adsorption was confirmed in view of its higher content in the surface coatings. The importance of ferromanganese oxides for Pb and Cd adsorption to the natural surface coatings developed in different seasons was evidenced. 展开更多
关键词 iron oxides manganese oxides Pb and Cd adsorption natural water
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Simultaneous Determination of Calcium and Magnesium in Water Using Artificial Neural Network Spectro-Photometric Method 被引量:2
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作者 JI Hongwei LI Shuang XIN Huizhen CAO Hengxia 《Journal of Ocean University of China》 SCIE CAS 2010年第3期229-234,共6页
A new analytical method using Back-Propagation (BP) artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water, the Yellow River water and seawater is estab... A new analytical method using Back-Propagation (BP) artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water, the Yellow River water and seawater is established. By condition experiment, the optimum analytical conditions for calcium, magnesium and Arsenazo (Ⅲ) color reactions are obtained. Levenberg- Marquart (L-M) algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 11-10-2 (nodes). The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of kt take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviations of the calculated results for calcium and magnesium are 2.31% and 2.14%, respectively. The results of standard addition method show that the recoveries of calcium and magnesium are 103.6% and 100.8% in the tap water, 103.2% and 96.6% in the Yellow River water (Lijin district of Shandong Province), and 98.8%-103.3% and 98.43%-103.4% in seawater from Jiaozhou Bay of Qingdao. It is found that 14 common cations and anions do not interfere with the determination of calcium and magnesium under the optimum experimental conditions. The comparative experiments do not show any obvious differ- ence between the results obtained by this new method and those obtained by the classical complexometric titration method in seawater medium. This method exhibits good reproducibility and high accuracy in the determination of calcium and magnesium and can be used for the simultaneous determination of Ca^2+ and Mg^2+ in tap water and natural water. 展开更多
关键词 artificial neural network simultaneous determination natural water CALCIUM MAGNESIUM
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Effects of natural mineral-rich water consumption on the expression of sirtuin 1 and angiogenic factors in the erectile tissue of rats with fructose-induced metabolic syndrome 被引量:2
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作者 Cidalia D Pereira Milton Severo +2 位作者 Luisa Rafael Maria Joao Martins Delminda Neves 《Asian Journal of Andrology》 SCIE CAS CSCD 2014年第4期631-638,共8页
Consuming a high-fructose diet induces metabolic syndrome (MS)-Iike features, including endothelial dysfunction. Erectile dysfunction is an early manifestation of endothelial dysfunction and systemic vascular diseas... Consuming a high-fructose diet induces metabolic syndrome (MS)-Iike features, including endothelial dysfunction. Erectile dysfunction is an early manifestation of endothelial dysfunction and systemic vascular disease. Because mineral deficiency intensifies the deleterious effects of fructose consumption and mineral ingestion is protective against MS, we aimed to characterize the effects of 8weeks of natural mineral-rich water consumption on the structural organization and expression of vascular growth factors and receptors on the corpus cavernosum (CC) in 10% fructose-fed Sprague-Dawley rats (FRUCT). Differences were not observed in the organization of the CC either on the expression of vascular endothelial growth factor (VEGF) or the components of the angiopoietins/Tie2 system. However, opposing expression patterns were observed for VEGF receptors (an increase and a decrease for VEGFR1 and VEGFR2, respectively) in FRUCT animals, with these patterns being strengthened by mineral-rich water ingestion. Mineral-rich water ingestion (FRUCTMIN) increased the proportion of smooth muscle cells compared with FRUCT rats and induced an upregulatory tendency of sirtuin I expression compared with the control and FRUCT groups. Western blot results were consistent with the dual immunofluorescence evaluation. Plasma oxidized low-density lipoprotein and plasma testosterone levels were similar among the experimental groups, although a tendency for an increase in the former was observed in the FRUCTMIN group. The mineral-rich water-treated rats presented changes similar to those observed in rats treated with MS-protective polyphenol-rich beverages or subjected to energy restriction, which led us to hypothesize that the effects of mineral-rich water consumption may be more vast than those directly observed in this study. 展开更多
关键词 ANGIOPOIETINS erectile tissue hypersaline sodium-rich naturally sparkling mineral water receptors sirtuin 1 vascularendothelial growth factor
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A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species (Se(Ⅳ), Se(Ⅵ)) at trace levels in natural lake and river water samples 被引量:1
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作者 Ramazan Gürkan Halil brahim Ulusoy +1 位作者 Mehmet Akay Pinar Bulut 《Rare Metals》 SCIE EI CAS CSCD 2011年第5期477-487,共11页
A novel catalytic kinetic method is proposed for the determination of Se(Ⅳ), Se(Ⅵ), and total inorganic selenium in water based on the catalytic effect of Se(Ⅳ) on the reduction of Celestine blue by sodium su... A novel catalytic kinetic method is proposed for the determination of Se(Ⅳ), Se(Ⅵ), and total inorganic selenium in water based on the catalytic effect of Se(Ⅳ) on the reduction of Celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2-20 and 20-200 μg·L-1 of Se(Ⅳ) for the fixed-time method at 30℃. The experimental and theo- retical detection limits of the developed kinetic method were found to be 0.21 and 2.50 μg·L-1 for the fixed-time method (3 min). All of the variables that affect the sensitivity at 645 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se(Ⅳ) determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus as long as chelating agents of thiourea and thiosulphate. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The relative standard deviations (RSDs) for ten replicate measurements of 2, 10, and 20 μg·L-1 of Se(Ⅳ) change between 0.35% and 5.58%, while the RSDs for ten replicate measurements of 3, 6, and 12 μg·L-1 of Se(Ⅵ) change between 0.49% and 1.61%. Analyses of a certified standard reference material (NIST SRM 1643e) for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. The Se(Ⅳ), Se(Ⅵ), and total inorganic selenium in lake and river water samples have been successfully determined by this method after selective reduction of Se(Ⅵ) to Se(Ⅳ). 展开更多
关键词 selenium speciation Celestine blue catalytic effect kinetic spectrophotometry natural waters
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Determination of complexation capacity of trace metal-organic in natural water 被引量:1
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作者 Yang Yu ying Department of Chemistry, Inner Mongolia Teachers College for Nationalities, Tongliao 028000, China Wu Di, Hong Xia, Guo Bo shu Institute of Environmental Chemistry, Inner Mongolia Normal University, Huhhot 010022, China 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1999年第1期128-132,共5页
The complexation capacity for heavy metals (Cu, Cd, Pb) were determined by anodic stripping voltammetry in South China Sea, Hulun Lake and Wuliang Suhai. The conditional stability constants and complexation capacity i... The complexation capacity for heavy metals (Cu, Cd, Pb) were determined by anodic stripping voltammetry in South China Sea, Hulun Lake and Wuliang Suhai. The conditional stability constants and complexation capacity index were calculated. The data showed that the complexation capacity of the Hulun Lake was greater than that of seawater and Wuliang Suhai. The sequence of complexation capacity is C (CuL)> C (CdL)> C (PbL), the values are in concord with results of analysis on dissolved organic carbon. The conditional stability constants were in an opposite sequence: K (CuL)< K (CdL)< K (PbL). When log K are similar, the greater the complexation capacity, the greater the complexation capacity index. 展开更多
关键词 complexation capacity heavy metal ASV method natural water.
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Electrokinetic chemical characteristics of humic and dannic acids effecting on the natural water and its coagulation 被引量:1
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作者 Qu Jiuhui Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1997年第1期71-79,共9页
Taking streaming current(SC)as the electrokinetic parameter,this paper demon- strated the electrokinetic chemical characteristics of humic and dannic acids(HA and DA)in sus- pensions including turbid water,coagulated ... Taking streaming current(SC)as the electrokinetic parameter,this paper demon- strated the electrokinetic chemical characteristics of humic and dannic acids(HA and DA)in sus- pensions including turbid water,coagulated water and HA or DA contained water.Accordingly, the studies were carried out for determining the relationship between streaming current and zeta po- tential ζ(expressed by eleetrophoretie mobility EM)in above water conditions.In addition,the mechanisms of HA effecting on streaming current within or after coagulant addition and the elec- trokinetic detection principles for HA or DA were also investigated on experiments and theoretical analysis.The results indicated that the change of SC like ζ presented meaningful information con- cerning the degree for destabilization of a particulate suspension,and HA or DA in water could re- markably decrease the effect of inorganic coagulant upon streaming current,which is in accordance with their influence on coagulation. 展开更多
关键词 electrokinetic chemical characteristics humic acid dannic acid natural water.
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Water Security-based Hydrological Regime Assessment Method for Lakes with Extreme Seasonal Water Level Fluctuations:A Case Study of Poyang Lake,China 被引量:2
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作者 WAN Rongrong YANG Guishan +2 位作者 DAI Xue ZHANG Yanhui LI Bing 《Chinese Geographical Science》 SCIE CSCD 2018年第3期456-469,共14页
Extreme seasonal water level fluctuations characterize natural floodplain lakes in monsoon regions, which are crucial for ensuring lake water security, including flood prevention water supply and health of aquatic eco... Extreme seasonal water level fluctuations characterize natural floodplain lakes in monsoon regions, which are crucial for ensuring lake water security, including flood prevention water supply and health of aquatic ecosystem. In order to achieve this goal, we established a hydrological regime assessment method based on a set of hydrological indicators for lakes with heavy seasonal water level fluctuations. The results suggest that time-sensitive hydrological indicators and specific time scales for various water security aspects must be considered. We discovered that it is more practical and meaningful to combine the water level classification derived from statistical analyses with characteristic hydrological values linked to water security. The case study of Poyang Lake results show that there are no discernable trends of Poyang Lake water regime status over the last 35 years, and the two periods of poor status are in accordance with climate variation in the lake basin area. Scholars and policy makers should focus on both floods and droughts, which are the main water security problems for Poyang Lake. It is hoped that this multi-scale and multi-element hydrological regime assessment method will provide new guidelines and methods for other international scholars of river and lake water assessment. 展开更多
关键词 lake water regime assessment water security seasonal water level fluctuations natural lakes Poyang Lake
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Comparison of Pb,Cd Adsorption to Surface Coatings Developed in Natural Waters with that in Plant Effluents
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作者 DONG De-ming LI Yu +1 位作者 HUA Xiu-yi ZHANG Jing-jing 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2003年第4期417-421,共5页
The comparative studies of Pb and Cd adsorption to the surface coatings(Fe, Mn, Al oxides, organic materials, and associated minerals), which were developed on glass slides in five natural and two technical waters(pla... The comparative studies of Pb and Cd adsorption to the surface coatings(Fe, Mn, Al oxides, organic materials, and associated minerals), which were developed on glass slides in five natural and two technical waters(plant effluents), were carried out under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0 05 mol/L, 25 ℃ and pH 6 0). The classical Langmuir adsorption isotherm was applied to estimating the equilibrium coefficients of Pb and Cd adsorption to the surface coatings. The results show that the maximum adsorption of Pb and Cd to the surface coatings mentioned above varied widely. There was a systemic increase in the maximum adsorption of Pb and Cd to the surface coatings with increasing the contents of Mn and Fe oxides in the surface coatings in significant correlation, respectively, not only highlighting the relative importance of the metal oxide fraction for Pb and Cd adsorption to the surface coatings developed in natural and technical water samples, but also implying the same adsorption mechanisms of Pb and Cd to the surface coatings developed both in natural and technical water samples. 展开更多
关键词 Natural waters Plant effluents Surface coatings PB CD
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Suspended particulate and colloidal matter in natural waters
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作者 Ran, Yong Fu, Jia-Mo +2 位作者 Sheng, Guo-Ying Beckett, R. Hart, B.T. 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2000年第2期4-12,共9页
The association of pollutants (nutrients, heavy metals and organic compounds) with colloidal and suspended particle matter(SPM) plays a dominant role in determining their transport, fate, biogeochemistry, bioavailabil... The association of pollutants (nutrients, heavy metals and organic compounds) with colloidal and suspended particle matter(SPM) plays a dominant role in determining their transport, fate, biogeochemistry, bioavailability and toxicity in natural waters. A scheme for the fractionation and composition of colloidal and suspended particulate matter from river waters has been tested. Sieving, continuous flow centrifugation and tangential flow filtration were used to collect gram amounts of colloidal and particulate matters. The separation scheme was able to process large samples(100L), within reasonable times(1 day) and the apparatus was portable. The aquatic colloid was also separated with high resolution, and sized using sedimentation field\|flow fractionation technique. The mass\|based particle size distribution for the river water sample showed a broad size distribution between 0\^05 and 0\^4 μm with the maximum around 0\^14 μm. There was a systematic increase in the content of organic carbon, Mg, Ca, Na, Cu and Zn with decreasing particle size, highlighting the importance of the colloidal(<1 μm) fraction. 展开更多
关键词 suspended particulate colloidal matter natural waters pollutants CLC number: X132 Document code: A
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INDIRECT VOLTAMMETRIC DETERMINATION OF TRACE SULFATE IN NATURAL WATERS WITH THE ADSORPTIVE COMPLEX WAVE OF LEAD(Ⅱ)-TETRAKIS (4-TRIMETHYLAMMONIUM PHENYL) PORPHYRIN
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作者 Guo Cang LI Laboratory of Inorganic Analytical Chemistry, Research Center for Eco-Environmental Sciences, Academia Sinica, Beijing, 100085 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第11期985-988,共4页
The indirect voltammetric determination of trace sulfate (2.0×10^(-6)~4.0×10^(-5) mol/L ) with the adsorptive complex wave of lead(Ⅱ)-tetrakis (4-trimethylammonium phenyl) porphyrin (PbTTMAPP) is reported.... The indirect voltammetric determination of trace sulfate (2.0×10^(-6)~4.0×10^(-5) mol/L ) with the adsorptive complex wave of lead(Ⅱ)-tetrakis (4-trimethylammonium phenyl) porphyrin (PbTTMAPP) is reported.This method has been used for the analysis of natural waters with satisfactory results. 展开更多
关键词 INDIRECT VOLTAMMETRIC DETERMINATION OF TRACE SULFATE IN NATURAL waterS WITH THE ADSORPTIVE COMPLEX WAVE OF LEAD TT Pb TRIMETHYLAMMONIUM PHENYL PORPHYRIN TETRAKIS PP
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Investigation of Adsorption Rates of Pb, Cd, Cu, Co and Ni to Fresh-water Surface Coatings Developed in Nanhu Lake
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作者 DONGDe-ming ZHANGJing-jing LIYu ZHANGJun-zhi HUAXiu-yi YANGFan 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2004年第1期29-31,共3页
The adsorption kinetics of five heavy metals onto the natural surface coatings, which were collected in the Nanhu Lake in Changchun, Jilin Province, China, were investigated for the purpose of giving some explanations... The adsorption kinetics of five heavy metals onto the natural surface coatings, which were collected in the Nanhu Lake in Changchun, Jilin Province, China, were investigated for the purpose of giving some explanations for the mechanisms of heavy metal adsorption onto the surface coatings with initial metal ions of 5 μmol/L. The results show that firstly, the adsorption of heavy metals onto the surface coatings follows the first order kinetics; secondly, the double-constant rate equation is suitable to describing the adsorption of heavy metals selected onto the natural aquatic surface coatings, following the order K_ Cu>K_ Pb>K_ Co>K_ Ni>K_ Cd; thirdly, there is a significant correlation between the adsorption rate and the physical and chemical characteristics of heavy metals, such as E 0, Δ_fH 0_m, and Δ_fG 0_m based on the linear regression analysis. 展开更多
关键词 Natural lake water surface coatings Heavy metal Adsorption kinetics
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Water resources development in Turkey
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作者 Bulent Acma 《水道港口》 2010年第5期544-544,共1页
The Southeastern Anatolia Projec(tGAP),one of the most important projects for developing remarkable natural resources of the world,is accepted as a change for getting benefit from rich water and agricultural resources... The Southeastern Anatolia Projec(tGAP),one of the most important projects for developing remarkable natural resources of the world,is accepted as a change for getting benefit from rich water and agricultural resources of the Southeastern Anatolia Region.The GAP Project has been considered as a regional development projects through years,but the dimensions of sustainability,protection of environment and participatory have been attached to the master of the project in recent years.When the GAP Project is completed,the Upper Mesopotomia, the centers of many civilisation,will re-again its importance as it had in the ancient times,and will be alive a center of civilisation.Moreover,when the problem of water shortage and water supplies in the world for the future is kept in mind,the importance of Southeastern Anatolia′s water supplies will be doubled.For this reason,the GAP Project,developed by depending on water and natural resources of the region,will have an important place in the world.The aim of this study is to introduce the region with rich natural resources and the GAP Project.For this reason,firstly,the natural potential of the region will be introduced.Second,the GAP Project will be presented in details.In the third stage,the projects being processed for protecting the natural sources and environment will be analyzed.In the last stage,strategies and policies to develop and to protect the natural resources of the region in short,mid,and long terms will be proposed. 展开更多
关键词 natural and water resources TURKEY Southeastern Anatolia Region Southeastern Anatolia Project (GAP)
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High-Precision Direct Determination of the ^(87)Sr/^(86)Sr Isotope Ratio of Bottled Sr-Rich Natural Mineral Drinking Water Using MC-ICP-MS
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作者 YANG Yue-heng,WU Fu-yuan,XIE Lie-wen YANG Jin-hui,ZHANG Yan-bin(State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,100029,China) 《矿物学报》 CAS CSCD 北大核心 2011年第S1期1025-1025,共1页
Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the additio... Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the addition of radiogenic 87Sr produced by the beta decay of 87Rb with a half-life of 4.88 ± 0.05 Ga.Thus, 展开更多
关键词 Sr Isotope Ratio of Bottled Sr-Rich Natural Mineral Drinking water Using MC-ICP-MS High-Precision Direct Determination of the TIMS ICP MC
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Reflection--The Story of Water
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作者 Marijana Magdic Vlatka Husetovic Mirna Coljak 《Journal of Chemistry and Chemical Engineering》 2017年第3期107-115,共9页
Starting from the fact that water is quite arguably the source of life, the authors agreed to set up a project on water and name it: "REFLECTION". Particular focus was placed on the following issues: water in natu... Starting from the fact that water is quite arguably the source of life, the authors agreed to set up a project on water and name it: "REFLECTION". Particular focus was placed on the following issues: water in nature, importance of water in human life, physical and chemical properties of water, protection of water in nature. The aim of the project was to make students aware of the importance of water for health as well as to help them develop a rational relationship towards drinking water. In order to find answers to the issues raised, the authors designed worksheets, PowerPoint presentations, educational games (ecological postcards, dominoes, memory games, etc.). The authors even tried our hand at making a comic strip. Students learned about the influence of water on health, as well as about water content in particular foods. The long-term goal of the project is to introduce children to scientific approach and methodology. Through active participation and dialogue, students discover cooperative learning and acquire skills that will be beneficial to them as well as to the wider community. Working on the project, students' evidence that the role of an individual is a key one in building a better world. This insight helps develop their civic skills and attitudes that serve as the starting point for environmental education. The authors made numerous adaptations and implemented individual approach with the goal of training students for independent work and life according to their personal abilities in line with the principles of inclusive education. Students conduct experiments following step-by-step instructions on specially adapted worksheets. Each student gets positive feedback and experiences the joy of success that leads to the development of self-confidence and love of work and learning. 展开更多
关键词 water in nature water content in foods nature protection ECOLOGY education.
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Pilot Trial on the Efficacy and Safety of a Natural Mineral Water Rich in Hydrogen Carbonate on Functional Dyspepsia and Heartburn
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作者 Ute Pohl Annegret Auinger +1 位作者 Gordana Bothe Ralf Uebelhack 《Open Journal of Gastroenterology》 2016年第3期88-96,共9页
Background: Dyspepsia and heartburn are among the most frequent complaints of the upper gastrointestinal tract impacting quality of life. The present study aimed to investigate the impact of drinking a natural mineral... Background: Dyspepsia and heartburn are among the most frequent complaints of the upper gastrointestinal tract impacting quality of life. The present study aimed to investigate the impact of drinking a natural mineral water (medicinal product category “Heilwasser” in Germany) high in hydrogen carbonate (Staatl. Fachingen STILL) on functional dyspeptic complaints and heartburn. Methods: 56 men and women with self-reported heartburn were enrolled to this one-arm pilot study. They had to drink 1.5 L of a hydrogen carbonate rich mineral water each day over a course of six weeks. Participants reported the number and duration of heartburn episodes in a daily dairy. The Reflux Disease Questionnaire (RDQ), Quality of Life in Reflux and Dyspepsia questionnaire (QOLRAD) and the Gastrointestinal Quality of Life Index (GILQI) were used to assess the therapeutic course of the treatment and the Short Form Health Survey (SF-12) to assess general quality of life. Mean ± standard deviation were calculated and pre- and post-treatment changes were compared using the Wilcoxon test. Results: The consumption of a hydrogen carbonate rich mineral water decreased the number of heartburn episodes per week significantly by 4.8 ± 8.2 at the end of the study (p < 0.001). The duration of episodes was also significantly reduced by 25.7 minutes after six weeks of intervention (p < 0.001). Accordingly, the subjectively perceived severity of heartburn, regurgitation and dyspeptic complaints as well as the GERD dimension as assessed by Reflux Disease Questionnaire improved significantly. There was a significant improvement in the disease-specific quality of life as measured by the Gastrointestinal Quality of Life Index (p < 0.001) and by the Quality Of Life in Reflux and Dyspepsia (p < 0.001) questionnaires and the general health-related quality of life as assessed by SF-12 (p < 0.007). Conclusions: The present pilot study provides evidence that supplementation with natural mineral water rich in hydrogen carbonate may improve heartburn and dyspeptic symptoms, which finally resulted in an improvement of the subjectively perceived quality of life. Drinking mineral water rich in hydrogen carbonate may be an alternative remedy for the treatment of dyspeptic symptoms and heartburn. Trial Registration: Eudra CT No 2013-001256-36. 展开更多
关键词 HEARTBURN DYSPEPSIA Natural Mineral water “Heilwasser” Pilot Study Hydrogen Carbonate
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Rice cultivation on floating-beds in different natural waters
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作者 SONG Xiangfu WU Weiming JING Qianyu YING Huodong ZHU Ming ZOU Guoyan CNRRI,Hangzhou 310006,China 《Chinese Rice Research Newsletter》 1997年第2期4-5,共2页
Following the success in rice cultivation onfloating-beds in natural water in 1990,the eco-logical adaptability of growing rice on floating-beds was studied during the period of 1991-1993.Experiments were conducted in... Following the success in rice cultivation onfloating-beds in natural water in 1990,the eco-logical adaptability of growing rice on floating-beds was studied during the period of 1991-1993.Experiments were conducted in five dif-ferent types of natural waters in ZhejiangProvince from 28°35′ to 30°58′N and from 119°05′ to 121°11′E.The results indicated that:1)Yield of double-cropping early ricegrowing on floating-beds was lower than one 展开更多
关键词 Rice cultivation on floating-beds in different natural waters
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Effect of Sample Disturbance on Unconfined Compression Strength of Natural Marine Clays 被引量:15
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作者 刘汉龙 洪振舜 《海洋工程:英文版》 2003年第3期407-416,共10页
Quantitatively correcting the unconfined compressive strength for sample disturbance is an important research project in the practice of ocean engineering and geotechnical engineering. In this study, the specimens of ... Quantitatively correcting the unconfined compressive strength for sample disturbance is an important research project in the practice of ocean engineering and geotechnical engineering. In this study, the specimens of undisturbed natural marine clay obtained from the same depth at the same site were deliberately disturbed to different levels. Then, the specimens with different extents of sample disturbance were trimmed for both oedometer tests and unconfined compression tests. The degree of sample disturbance SD is obtained from the oedometer test data. The relationship between the unconfined compressive strength q u and SD is studied for investigating the effect of sample disturbance on q u. It is found that the value of q u decreases linearly with the increase in SD. Then, a simple method of correcting q u for sample disturbance is proposed. Its validity is also verified through analysis of the existing published data. 展开更多
关键词 correcting method degree of sample disturbance liquid limit natural marine clays natural water content oedometer test data unconfined compressive strength
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On Physical and Mechanical Behavior of Natural Marine Intermediate Deposits 被引量:5
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作者 石名磊 邓学钧 《China Ocean Engineering》 SCIE EI 2005年第1期111-119,共9页
Coastal structures may be built on natural sedimentary intermediate grounds, which mainly consist of silty soils and fine sandy soils. In this study, extensive field and laboratory tests were performed on the natural ... Coastal structures may be built on natural sedimentary intermediate grounds, which mainly consist of silty soils and fine sandy soils. In this study, extensive field and laboratory tests were performed on the natural marine intermediate deposits to demonstrate the difference in behavior between natural marine clayey soils and natural marine intermediate deposits. The natural intermediate deposits have almost the same ratios of natural water content to liquid limit as those of the soft natural marine clays, but the former have much higher in-situ strength and sensitivity than the latter. The research results indicate that grain size distributions of soils affect significantly tip resistance obtained in field cone penetration tests. The mechanical parameters of natural marine intermediate deposits are also significantly affected by sample disturbance due to their high sensitivity and relatively large permeability. Unconfined compression shear tests largely underestimate the strength of natural marine intermediate soils. The triaxial consolidated compression shear tests with simulated in-situ confined pressure give results much better than those of uncomfined compression shear tests. 展开更多
关键词 clayey soils filed tip resistance grain size distributions liquid limit natural marine intermediate deposits natural water content laboratory strength
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Determination of gross α and β activities in Zouma River based on online HPGe gamma measurement system 被引量:3
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作者 Xian Guan Liang-Quan Ge +3 位作者 Guo-Qiang Zeng Xiao-Qin Deng Li-Peng Xu Sheng-Liang Guo 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2020年第12期65-76,共12页
This paper describes a low-cost and fast method to evaluate gross α and β^(-) radioactivities in natural water based on an online high-purity germanium detector gamma measurement system.The major gamma activities in... This paper describes a low-cost and fast method to evaluate gross α and β^(-) radioactivities in natural water based on an online high-purity germanium detector gamma measurement system.The major gamma activities in natural water are provided by natural and artificial radionuclides such as ^(40) K,^(137)Cs,and radionuclides belonging to ^(238)U and ^(232)Th series.The main a emitters related to gamma emissions in natural water are ^(224)Ra(240.98 keV)and ^(226)Ra(186.21 keV),and the β^(-) emitters are ^(40) K(1460.85 keV),^(214)Bi(609.31 keV),^(208)Tl(583.19 keV),and ^(214)Pb(351.93 keV).The formula for gross α and β^(-) activity concentration is based on these radionuclides,and the short half-life decay products are considered in the calculation.The detection efficiency of the device across energy region(0–3 MeV)is obtained through Monte Carlo simulation,and a calibration experiment is conducted to verify the simulation results.Gamma radioactivity is measured continuously for 114 d in Pixian County and Dongfeng Canal located in the Zouma River,Chengdu,Sichuan Province,China.A comparison of the calculation results and monitoring data from the Sichuan Management and Monitoring Center Station of Radioactive Environment indicates that the percentage and absolute error of a activity concentration is lower than 53%and 0.02 Bq/L,respectively,and that of β-activity concentration is lower than 33.2%and 0.016 Bq/L,respectively.The method can rapidly determine gross α and β^(-) activity concentrations in natural water online. 展开更多
关键词 Grossαandβ^(-)activity HPGe gamma spectrometer Online radioactivity level measurement for natural water Natural radioactivity water sources of Chengdu
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