Use of Plant Bioassays for the Detection of Genotoxins in the Aquatic Environment     

Bernhard J. Majer  Tamara Grummt  Maria Uhl  Siegfried Knasmüller 《洁净——土壤、空气、水》2005,33(1):45-55

The present article describes the use of plant bioassays for the detection of genotoxins in the aquatic environment and gives an overview of test methods, their detection spectrum for environmental mutagens and carcinogens and their limitations and pitfalls. The most widely used test systems are micronucleus assays with meiotic cells of Tradescantia and with meristematic root tip cells of Allium and Vicia. In the last years, protocols for single cell gel electrophoresis assays have been developed, which can be conducted with a variety of species. Also various gene mutation test procedures have been developed with plants but they have hardly ever been used in environmental studies. Plants detect a broad variety of environmentally relevant genotoxins, in particular directly acting compounds. Many pesticides and industrial chemicals caused positive results; plant assays are also a unique tool for the detection of DNA‐reactive carcinogenic heavy metals in the environment. In many studies with complex mixtures, positive results were obtained which indicates that plants are sufficiently sensitive to detect effects without concentration of water samples. One of the shortcomings of the use of plants as indicators is their lack of sensitivity towards certain classes of promutagens such as nitrosamines, heterocyclic amines, and polycyclic aromatic hydrocarbons (PAHs). However, the former compounds are hardly encountered in the environment and PAHs can easily be detected chemically and in other mutagenicity tests. Taken together, the currently available data show that plant bioassays are a useful component of test batteries for environmental monitoring.  相似文献   

Radiocaesium dispersion and fixation in the lagoon systems of “Ria de Aveiro”, Portugal     

Iuliu Bobos  Fernando Rocha 《Journal of Geochemical Exploration》2006,88(1-3):367

Radiocaesium (¹³⁷Cs) dispersion and Cs⁺ fixation were studied in the sediments collected from the lagoon systems of “Ria de Aveiro”. The Cs⁺ sorption was tested for the fine mica grains and for the < 2 μm clay fractions extracted from silty clays. The Cs⁺ exchange is found strongly onto mica-rich fractions than smectite-rich fractions. The distribution coefficient increases if the silty material is constituted by rich-mica clay fractions or if the non-clay minerals are removed from the silty-clay material. The samples studied behave as multisite ion exchange, where Cs⁺ engages in ion-exchange reactions with hydrated cations on planar sites on expansible layer silicates. Higher concentrations of the ¹³⁷Cs were found associated with mica-rich silty clays. The ¹³⁷Cs ranges from 3.2 to 3.9 Bq kg^− 1 in the < 38 μm fractions and from 2.9 to 3.3 Bq kg^− 1 in the < 64 μm fractions.  相似文献   

长城式金矿稳定同位素地质特征   总被引：3，自引：0，他引：3       下载免费PDF全文

王郁 《地质找矿论丛》2000,15(3):254-260

长城式金矿是近几年在冀东地区发现的一种新的金矿类型,该类型金矿产在中元古界碳酸盐岩及碎屑岩地层中,文章阐述了金矿床的硫、铅、氢、氧、碳等同位素地球化学特征,从而提供了矿床成因信息。  相似文献   

Rapid response of forested vegetation to multiple climatic oscillations during the last deglaciation in the northeastern United States     

Zicheng Yu 《Quaternary Research》2007,67(2):297-303

Isotopic and pollen results from a marl lake (White Lake) in the Mid-Atlantic region of USA indicate the coupling of climate and vegetation changes. Oxygen isotopes of calcite from this site show multiple oscillations at millennial and centennial scales, including the Younger Dryas with 3‰ negative shifts in δ¹⁸O at 12.4-11.4 ka (1 ka = 1000 cal yr BP) and three cold events of magnitude 1-2‰ shifts during the Bølling-Allerød warm period (BOA) at 14.3-12.4 ka. Pollen data from the same core show nearly synchronous, close correspondence with isotope-inferred climate shifts, indicating rapid forest response to deglacial climate oscillations in southern New England. A plateau-like BOA is similar to other records around the North Atlantic Ocean.  相似文献   

试论汾渭“S”型旋转拉分构造体系及其影响     

李述靖  吕古贤 《现代地质》2021,35(5):1260-1266

汾渭地堑系位于我国东部阴山与秦岭纬向带之间,自北向南,由集宁、怀来、大同、蔚县、忻州、太原、晋中、汾渭、天水、礼县、西和、成县等10余个NE向斜列的新生代断陷盆地组成,它们呈“S”形展布,反映华北地块在新生代时期发生了顺时针旋转,使古老地块发生裂解,可称之为“S”型旋转拉分构造体系。这个构造体系对中国东部构造格局和构造发展有广泛和深远的影响,强烈改造了秦岭—大别山纬向构造带和江南地块北缘的构造格局,使新华夏系形成分段特征,启动了华北地块伸展构造发展模式,影响所及直达琉球海沟。无独有偶,亚洲中部俄罗斯、蒙古境内有贝加尔地堑系,由反“S”形分布的新生代断陷盆地组成,它们也发育于古老结晶地块之中,可与之对比,是逆时针旋转的反“S”型旋转拉分构造体系。说明它们是同一类型的旋转构造型式,是古老地块裂解的一种方式。  相似文献   

碎屑岩沉积从源到汇的“物-坡”耦合效应^*          下载免费PDF全文

于兴河  李顺利  孙洪伟 《古地理学报》2022,24(6):1037-1057

碎屑岩沉积体系的三维展布特征及其成因机制是建立沉积模式与预测其砂体分布的关键,更是沉积学研究的关键性科学问题。国内外绝大多数学者认为其平面形态和剖面充填型式均与其沉积的地形坡度、粒度粗细有密切的联系,但其定量关系并不清楚。建立不同类型沉积体中粒度和坡度之间的定量关系,对于预测沉积体中不同颗粒的运动方式及其分布至关重要。应用“源-汇”系统研究的思路,分析了供源区、搬运(输送)区及汇积区各自的地质特点,从单向水流对不同质量颗粒在静止/运动中的受力分析与沉积前总体地形斜坡设定2个角度,系统分析、推导并模拟了不同碎屑颗粒在纵向剖面上的运动轨迹,其表现为随着设定的坡型呈抛物线变化,反映出沉积物输送营力的变换及其随坡度变化的响应特征。建立了陆相碎屑岩沉积体系纵向剖面的流速与坡度的计算方程,明确指出沉积物的流速或流态决定其沉积方式,阐述了汇积区碎屑颗粒的加积型式与沉积物分布上的总体规律,由此提出碎屑岩沉积体系的“物-坡”耦合效应及其主要内涵,并从多个维度与源-汇的各区段,阐述了“物-坡”耦合效应在各种沉积体系的沉积物类型及其空间形态特征上的地质响应。  相似文献   

DECLINING STUDENT PERFORMANCE IN COLLEGE GEOGRAPHY AND THE DOWN-WRITING OF TEXTS     

Stanley W. Trimble 《The Professional geographer》1986,38(3):270-273

Student preparation for college showed significant declines through the 1970s, according to Scholastic Aptitude Tests and other indices. During the same period, scores declined on my standardized, mid-term exam used for introductory physical geography at UCLA. I suggest that the latter is primarily caused by the former. As a result of declining preparation and abilities, many physical geography texts have been down-written to a high-school level. These texts have grave implications for the quality of learning, recruiting of quality students, and academic respect for geography as a discipline.  相似文献   

细粒含量Pc＜25％渗透变形类型为非管涌碎砾石的颗粒级配特征及判别方法     

齐俊修  赵晓菊  刘艳  张中炎  张广禹 《冰川冻土》2016,38(4):977-981

细粒含量判别法是无黏性粗粒土渗透变形类型主要判别方法,但细粒含量Pc25%渗透变形类型为流土和过渡的碎砾石,其渗透变形类型不符合细粒含量判别准则.通过对46个工程310个试样(其中Pc25%的试样数214个),渗透变形试验结果统计分析发现,该类土虽然仅占同级配段(Pc25%)比例为6.1%,但其颗粒级配曲线均具有独特特征,即各粒径级颗粒含量均较均匀,即Cu均大于5,Cc多数为1.0~3.0之间,即该类土大多数为优良级配,进一步分析发现其D15/d85之比均小于等于5,进而提出用D15/d85≤5作为判别该类土的方法.  相似文献   

长江下游地区降水50-80d低频分量的次季节预测研究   总被引：1，自引：0，他引：1  

杨秋明 《气象学报》2016,74(4):491-509

用1979-2000年逐日长江下游降水的50-80 d低频分量和全球850 hPa低频纬向风主成分,构建了长江下游降水低频分量的次季节预测的扩展复数自回归模型（ECAR）。这种基于数据驱动建模的气候预测方法,不仅能在复数空间上反映全球环流主要低频主分量和长江下游降水低频分量之间的时滞变化信息,而且能更好地描述气候系统的主要分量在低维空间中的变化规律。对2001-2014年长江下游降水低频分量进行次季节逐日变化回报试验的结果表明,50-80 d时间尺度的长江下游低频降水分量的预测时效可达52 d左右,预报能力明显优于自回归模型（AR）,而且6-8月的预报技巧最高。基于全球环流主要50-80 d振荡型的发展和变化以及与长江下游低频降水相关的时间演变,对于提前50-60 d预报长江下游地区持续多（少）雨过程很有帮助（尤其是夏季）,其中,东亚经向三极子型（EAT）是影响长江下游地区季节内降水变化的最主要的环流因子之一。   相似文献   

基于Ripley'K函数的延吉市区崩塌地质灾害空间格局研究     

钱立辉  王抒群  李忠水  孙秀菲 《测绘与空间地理信息》2016,(1)

崩塌是较为严重的一种地质灾害,研究崩塌体的空间格局有利于政府部门对其做出防治决策。本文基于最新时相的延吉市区高分1号遥感影像,从崩塌地质灾害成灾机理的角度,选取了如植被指数、土壤亮度指数、坡度等主要指标,并结合了前人对崩塌影像光谱特征的研究成果,建立了本次的自动化解译模型,在成功提取崩塌体后,经过栅矢数据转换,选用ArcGIS 10软件的K函数分析模块,进行了崩塌灾点的空间格局分析。  相似文献