微波消解-电感耦合等离子体质谱法测定超细粒度岩石和土壤样品中的稀土元素   总被引：2，自引：1，他引：1  

王娜  徐铁民  魏双  王家松  曾江萍  张楠 《岩矿测试》2020,39(1):68-76

应用电感耦合等离子体质谱法(ICP-MS)分析岩石和土壤样品中稀土元素的含量,取样量可低至数毫克级,但200目样品粒度要求分析取样100mg才能保证代表性,导致ICP-MS灵敏度高、取样量小的优势难以得到充分发挥。本文研究了研磨方式、研磨时间、物料比对超细粒度土壤和岩石样品制备的影响,结果表明采用乙醇作为分散剂进行湿法球磨,200目粒度的土壤、岩石样品分别研磨10min和15min,土壤样品的物料比采用物料7g、研磨球500个、分散剂45mL,岩石样品的物料比选取物料5g、研磨球500个、分散剂45mL,细化程度最佳。在此条件下制备的超细粒度土壤标准物质GBW07404、GBW07447的粒径分布D_(95)可低至7.51μm、7.05μm,超细粒度岩石标准物质GBW07104、GBW07121的D_(95)可低至8.42μm、8.30μm。在硝酸-氢氟酸-过氧化氢酸溶体系中微波消解处理超细粒度岩石标准物质GBW07104,取样量减少至5mg,总用酸量减少至0.25mL,消解时间降低为25min,稀土元素的测定值与认定值基本一致,相对标准偏差在1.64%～5.21%之间。该方法用于分析其他超细粒度标准物质(GBW07404、GBW07447和GBW07121)中的稀土元素,相对误差为0.17%～6.60%,满足《地质矿产实验室测试质量管理规范》的一级标准。  相似文献   

杭州湾及其邻近海域表层沉积物的沉积环境分区及重金属污染特征分析   总被引：1，自引：0，他引：1  

柴小平  魏娜  任世军  母清林  胡序朋  杜晓琴 《海洋科学》2019,43(8):29-35

于2017年春季和2018年春季,分两个航次,在杭州湾及其邻近海域采集了表层沉积物样品,并对其粒度组成及重金属含量进行了测定。结果表明,研究区域表层沉积物的粒级组成以砂和粉砂为主,平均占比分别为38.0%和55.4%。根据粒级组成的区域分布特征,将研究区域分为长江河口现代沉积区(Ⅰ-1)、钱塘江河口现代沉积区(Ⅰ-2)、长江羽状锋面积聚区(Ⅱ-1)、长江次级锋面积聚区(Ⅱ-2)、岛屿风化影响区(Ⅲ)、残留砂混合沉积区(Ⅳ)等4大类6个亚区。通过比较不同区域重金属含量发现,总体分布趋势为Ⅱ-1区和Ⅱ-2区含量较高,Ⅰ-2区和Ⅳ区含量较低,Ⅰ-1区和Ⅳ区相对居中。单因子污染指数评价结果显示,Ⅱ-1区和Ⅱ-2区的Cu、Pb、Zn、As、Cd、Hg已呈现出污染态势,需引起关注;Cr则未呈现出污染态势。  相似文献   

Facies analysis of the Middle and Late Quaternary sediment infill of the northern Weihe Basin,Central China          下载免费PDF全文

Daniël S. Rits  Maarten A. Prins  Simon R. Troelstra  Ronald T. van Balen  Yan Zheng  Christiaan J. Beets  Bin Wang  Xiaoqiang Li  Jie Zhou  Hongbo Zheng 《第四纪科学杂志》2016,31(2):152-165

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Effect of connecting rain barrels on the storage size reduction     

Yongwon Seo  Nam‐Jeong Choi  Daeryong Park 《水文研究》2012,26(23):3538-3551

In this article, the possibility of sharing rain barrels and the potential benefit of reducing storage size through physical and non‐physical connections of rain barrels in a community are investigated. Using the concepts of homogeneous/heterogeneous users in rainwater harvesting systems (RWHS), two simple cases of a community composed of four prospective users are examined. The first is performed with the users who have the same mean and variance in water demands (homogeneous users), and the second is with the users with different means and variances (heterogeneous users). To take account for the rainfall characteristics in different places, historical records from six cities in the USA are used for storage–reliability–yield analysis. The result indicates that required total storage can be reduced by connecting multiple rain barrels. In addition, a significant difference is found between homogeneous and heterogeneous user groups. Homogeneous users do not achieve a substantial benefit from connecting their rain barrels; these users may even be disadvantaged by sharing. In contrast, heterogeneous users receive benefit by reducing the total required storage. Most benefit is expected between users with maximum difference in mean water demands. The reduction in storage size was as considerable as 37% in this study. The quantity of storage reduction depends on locations and target reliabilities. Knowledge of the benefits and limitations of rain barrel connections can improve RWHS performance through ability to customize a network plan for individual users. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Borehole failure analysis in a sandstone under anisotropic stresses     

Euripides Papamichos 《国际地质力学数值与分析法杂志》2010,34(6):581-603

Borehole failure under anisotropic stresses in a sandstone is analyze numerically for various borehole sizes using a nonlinear elastic–plastic constitutive model for a Cosserat continuum. Borehole failure is identified as macroscopic failure of the borehole through the development of shear bands and breakouts. The results compare well both qualitatively and quantitatively with experimental results from polyaxial tests on Red Wildmoor sandstone. They show that the hole size effect of the borehole failure strength is independent of the far‐field stress anisotropy and follows a ? power law of the hole size. A similar scale effect equation with a ? power law is proposed for the scale effect of the maximum plastic shear strain at failure. This equation can be useful for better predicting hole‐size‐dependent failure with standard codes based on classical continua. The effect of stress anisotropy on the borehole failure stress is found to be independent of the hole size. The failure stress decreases linearly to 40% as the stress anisotropy increases. However, the maximum plastic shear strain at failure is stress anisotropy independent and therefore the critical plastic shear strain for failure is only hole‐size dependent. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

九龙江河口区现代沉积环境及其物质输运趋势   总被引：1，自引：0，他引：1  

方建勇  陈坚  王爱军  李东义  黄财宾 《海洋地质与第四纪地质》2010,(2)

对九龙江河口区58个表层沉积物样品进行了激光粒度分析,并分别应用系统聚类分析和GSTA模型分析,探讨了研究区的沉积特征、沉积环境和表层沉积物输运趋势。结果表明,九龙江河口区表层沉积物由10种沉积物类型组成,与20世纪80年代相比,该海区底质沉积物在类型分布和粒径粗细上发生了一定的变化;将研究区划分为3种与沉积动力特征相对应的主要沉积环境区;表层沉积物输运趋势因受该区特殊的地形和复杂的水动力条件影响而表现为北进南出,海门岛西北海域形成逆时针方向输运趋势,而海门岛以东海域形成三向汇聚的输运趋势。  相似文献   

Limpets as prey: Lipophrys pholis choice for size     

Ana C. Silva  Ana C. Amador  Sónia Brazão  Claúdia Faria  Diana Boaventura 《Marine Ecology》2010,31(4):525-532

Patellid limpets are key species on rocky shores, structuring intertidal assemblages through their grazing. Their role as prey for fish is, however, often overlooked in studies of intertidal ecosystem functioning. The shanny Lipophrys pholis is a common predator of limpets on rocky shores in Northern Europe and, in this study, we examined the characteristics of its predation on limpets based on prey size. The limpet size range that adult L. pholis (10–12.5 cm) can eat was examined in the laboratory using Patella depressa in 0.2 cm classes, varying between 0.5 cm and 3.0 cm in maximum shell length. There was a limpet size refuge above 1.8 cm, while all smaller sizes were readily consumed by the shanny. The predator attacking behaviour was also examined and found to vary with prey size. Limpets up to 0.8 cm were crushed by the jaw‐constricting force and eaten whole, whereas larger prey were prised from the substratum and the body subsequently separated from the shell. To examine whether there was a L. pholis preference for P. depressa size, a two‐stage laboratory experiment was done using two size classes defined as small (0.7–0.8 cm maximum shell length) and large (1.5–1.6 cm maximum shell length). In the first stage, the predator was given each limpet size class separately. In the second stage, the fish was given a choice between the two classes. Lipophrys pholis was shown to have a preference for the large size class (1.5–1.6 cm). The average number of limpets consumed by the shanny was examined for the duration of one high‐tide typical of the central region of Portugal (≈ 4 h). On average, approximately five limpets (up to an eight limpet maximum) were consumed. The present study shows that L. pholis has a feeding preference based on limpet size, which suggests that the limpet population structure and intra‐ and inter‐specific interactions may be influenced by the shanny predation.  相似文献   

Influences of coupled wind–water processes on suspended sediment grain size: an example from tributaries of the Yellow River / Influences de processus couplés éoliens-hydriques sur la granulométrie des matières en suspension: exemple d'affluents du Fleuve Jaune     

《水文科学杂志》2013,58(5)

Abstract

Some unique coupled wind–water erosion processes exist in the desert-loess transitional zone in the middle Yellow River basin. Based on data from 40 stations on 29 rivers, a study was made on the influence of such processes on suspended sediment grain-size characteristics of the tributaries of the Yellow River. Results show that the percentage of >0.05-mm grain size decreases with the increased annual mean precipitation, but increases with the increase in the annual mean number of sand-dust storm days. The percentage of <0.01-mm grain size increases with the increase in the annual mean precipitation, but decreases with the increase in the annual number of sand-dust storm days. Based on annual mean data from 40 stations, multiple regression equations were established between the percentages of >0.05-mm grain size (r _>0.05) and <0.01-mm grain size (r _<0.01), annual mean precipitation (P _m) and annual mean number of sand-dust storm days (D _ss). On this basis, the relative contributions of the variations in D _ss and P _m to the variation in r _>0.05 and r _<0.01 were estimated. The results indicate that the variation in sand-dust storm frequency exerts greater influences on the variation in grain-size characteristics of suspended load than does the variation in annual mean precipitation. With the increase in the coupled wind–water processes index, expressed by P _m/D _ss, the percentage of >0.05-mm grain size in suspended sediment decreases and the percentage of <0.01-mm grain size increases. With the variation in P _m/D _ss, different combinations of r _>0.05 with r _<0.01 appear, which have some influence on the formation of hyperconcentrated flows. There exist some optimal ratios of coarse to fine fractions in suspended sediment that make sediment concentrations of hyperconcentrated flows the highest. The optimal r _>0.05/r _<0.01 value is related to some range of the index P _m/D _ss. When the P _m/D _ss index falls in this range, the optimum combination of relative coarse with fine sediments in the suspended load appears, and thus results in the peak values of sediment concentration.  相似文献   

Numerical analysis of frost effects in porous media. Benefits and limits of the finite element poroelasticity formulation     

Stéphane Multon  Alain Sellier  Bernard Perrin 《国际地质力学数值与分析法杂志》2012,36(4):438-458

The aim of this paper is to analyse the performance of a finite element formulation usable for predicting the mechanical consequences of frost effects on porous media. It considers the characteristics of porous media and how the frost action can be assessed. The problem is then separated into two parts: thermal and poromechanical calculations. The constitutive equations developed in the framework of poromechanics are presented and the implementation in a usual finite element poroelasticity formulation based on Zuber's method is adopted. An analysis of the time‐step influence on the convergence rate is given and leads us to propose a simple method in order to obtain objectivity of the finite element response and avoid over‐long calculations. Frost effect simulations are carried out on real porous media (two fired clays) as a case study. Although the experimental behaviour of the porous media subjected to frost action is in accordance with some observations, the calculated strains appear to be overestimated compared with measurements. The problem could be largely attributable to the difficulty of assessing permeability evolution during frost development. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

环境样品中甲基汞的检测方法综述   总被引：1，自引：0，他引：1  

孙维萍  潘建明  翁焕新  朱利中  郑旻辉 《海洋学研究》2010,28(2):45-51

综述了常用的环境样品中甲基汞的检测方法和检测步骤,认为在实际的甲基汞检测过程中,选择或评价所选用检测方法的原则通常是,在确保检测限的基础上,首选考虑检测结果的精确度如何,而快捷方便、经济实惠的检测技术也是现实运用中的实际需要。作为定量检测,GC分别与AAS、AES、AFS的联用是目前较常用的技术,而与ICP-MS或ID-ICPMS的联用,在今后的实际检测中将得到更广泛的运用。生物传感器检测到的汞一般是生物可利用的汞,降低其检测限并将其作为对污染水体与沉积物检测的重要方法,也是今后研究的重点。总之,在人类对环境安全和身体健康日益重视的今天,发展高灵敏度、高准确度、快速方便和低成本的检测技术是未来甲基汞检测的重要发展方向。  相似文献