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 <i>Tradescantia</i> and with meristematic root tip cells of <i>Allium</i> and <i>Vicia.</i> 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   

Tectonometamorphic evolution of the Chuncheon amphibolite, central Gyeonggi massif, South Korea   总被引：9，自引：0，他引：9  

SEUNG RYEOL LEE  MOONSUP CHO 《Journal of Metamorphic Geology》1995,13(2):315-328

Abstract The Chuncheon amphibolite, part of the Gubongsan Group which overlies the Yongduri gneiss complex, is interlayered with calc-silicate rock, marble, quartzite, biotite schist and quartzofeldspathic gneiss in the central Gyeonggi massif, South Korea. Metamorphic pressures and temperatures estimated from the amphibolite are 5.5–10.6 kbar and 615–714°C. These P—T conditions are close to those defined by the reaction curve between kyanite and sillimanite, and suggest medium-pressure-type metamorphism of the Chuncheon amphibolite. For two metapelites intercalated with the amphibolite, temperatures are estimated to be 607–699° C, consistent with those obtained from the amphibolite. On the other hand, pressures estimated from these metapelites are significantly different, 4–6 kbar and 9–13 kbar, when rim and core compositions of garnet are, respectively, used. These P—T estimates obtained from the amphibolite and metapelite suggest a nearly isothermal decompression of 3–7 kbar during denudation. Rapid decompression is likely on the basis of the results of mineral chemistry, phase equilibria and geothermobarometer. Moreover, in conjunction with the occurrence of kyanite in the adjacent Gyeonggi gneiss complex, P—T estimates of the Chuncheon amphibolite and metapelite suggest a clockwise P—T—t path. This evolutionary path may be related to the amalgamation of continents during the late Proterozoic event which corresponds to the Jinningian orogeny in the Qinling belt of China.  相似文献   

1626年灵丘地震烈度分布特征与阻震构造初步讨论   总被引：1，自引：0，他引：1  

申旭辉  汪一鹏 《华北地震科学》1995,(1)

对１６２６年灵丘地震的破坏情况进行了重新考证，着重指出了灵丘地震烈度沿唐河大断裂的高值异常和向西的快速衰减特征。在此基础上，提出了阻震构造的概念并进行了相应的理论分析。文章最后指出：唐河大断裂是１６２６年灵丘地震的阻震构造。  相似文献   

热液铀矿床中的红化问题     

张宏 《华东地质学院学报》1988,(1)

按红化与铀矿化形成的先后关系,将热液铀矿床(特别是碱交代型铀矿床)中的红化划分出三种成因类型:原生红化、同生红化和后生红化。其中后生红化又分为次生红化和表生红化。讨论了红化不同成因类型的可能形成机理:空洞效应导致原生红化;铁—铀氧化还原作用导致同生红化;辐射作用导致次生红化;O_2对Fe~(2+)的氧化作用导致表生红化。作出了在成矿热液所处的物理化学条件下铁—铀氧化还原反应的pH—Eh图和pH—PUO_2图。肯定了在成矿热液所处的物化条件下铁—铀反应的可能性。原生红化与矿化关系不大,它作为开放式碱交代的标志之一:同生红化与矿化关系密切;次生的红化可作为构成找矿标志的一个因素;表生红化意义不大。  相似文献   

滇西南地区五年内大震形势预测     

闻满华 《地震》1994,(5):84-91

本文采用极值理论、线性预测和最大熵谱分析三种不同的概率统计预报方法，从不同的角度对滇西南地区地震活动进行研究，得到滇西南５年内将有１次６．５－６．９级地震活动，１９９２年有６．０－６．４级发震可能的中短期预报结果。  相似文献   

电解富集光谱法测定样品中的微量金     

冯正光  张辉俊 《矿物岩石》1994,14(2):98-101

本文先以恒电位电解法在ｃ（Ｋｃｌ）＝０．ｌｍ０ｌ／Ｌ，ｃ（Ｈｃｌ）＝０．２ｍｏｌ／Ｌ介质液中，将微量金电解富集在特制石墨电极上，再用背景为内标的原子发射光谱法对金进行测定。本分析方法的回收率为９７．１－１０６％，变动系数为８．５５％，相对误差为－１．９６一２．２１％。操作简便快速，测定结果准确可靠  相似文献   

大尺度凝结水在下落过程中的蒸发对模拟气候特征的影响     

黄丹青  钱永甫 《大气科学》2006,30(6):1160-1168

将新的大尺度凝结水在降落过程中蒸发量计算的方案引入p-σ混合坐标系初始方程九层模式中, 运用1979～1995年NCEP/NCAR再分析资料月平均场作为初始场和侧边界强迫, 模拟得到1月和7月气候特征, 并用F检验和t检验方法检验了原大尺度凝结方案与新方案模拟结果差异的显著性.结果表明, 在大尺度凝结降水中出现蒸发的大部分地区为我国东部和南部的沿海地区以及相应的海洋上.模拟的气候特征的差异主要集中在我国东部以及东南沿海一带的大陆和海洋, 其中在总降水场的模拟结果中, 较好地消除了原模式在华北地区的虚假大值区.检验结果表明, 7月的差异比1月的显著, 而且各要素平均值的差异不大, 方差的差异比较显著.  相似文献   

Shifts in the Processes of Oxygen and Nutrient Balances in the River Elbe since the Transformation of the Economic Structure     

H. Guhr  B. Karrasch  D. Spott 《洁净——土壤、空气、水》2000,28(3):155-161

The reduction of pollution in the river Elbe since 1990 has resulted in changes in the processes taking place in the river. The heterotrophic degradation which dominated until 1990 was accompanied by a lack of oxygen, floating masses of sewage fungi, and sludge formation in the areas of still water. Since the early 1990s, autotrophic processes have come to dominate, with an increase in pH fluctuations and the oxygen production potential, but evidently not the chlorophyll level during the growing season. The degradable organic pollution of the Elbe is determined by algae production. The high levels of ammonium previously encountered in the Elbe were attributable to not only dischargers but also in particular the lack of oxygen in the water. Via heterotrophic nitrate assimilation, nitrate served as an oxygen reserve, resulting in high levels of nitrite. At present, when the oxygen contents are sufficient, the concentration reductions of nitrate and nitrite along the reach of the Elbe are approximately parallel, which in view of the lack of ammonium indicates the denitrification of microzones low in oxygen. The relative proportion of structurally bound substance turnover will become increasingly important for the Elbeπs material budget.  相似文献   

利用到时差分布图方法进行近场地表震源定位          下载免费PDF全文

史鹏程  王元  游庆瑜 《地球物理学报》2017,60(8):3119-3132

近场震源的高精度定位在工程建设与军事应用等方面意义重大且应用广泛,如炮弹落点定位或车辆追踪等.定位过程面临速度结构未知、高分辨率要求等问题,传统的震源定位方法有一定的局限性.本文将超声波检测中的时差分布图(Delta T Mapping,简称DTM)方法首次成功引入近场震源定位问题中.DTM定位法首先建立一个测区的到时差模型,然后基于此模型对新的震源进行定位.有两种建立模型的方法,(1)网格搜索法:对原有模型进行线性插值,得到更高分辨率的到时差分布模型;(2)统计定位法:利用高斯过程回归建立到时差数据与位置坐标之间的映射关系.本文在北京某郊区进行了炸点定位实验,在140 m×90 m的测试区域内,定位误差为0.5~5.1 m.结果表明,DTM方法是一种可靠、高精度、具有近实时性的近场震源定位方法.进一步利用接收点、源点互换,在获得高精度DTM同时,可大幅降低标定与数据分析成本.结合震源扫描法具有解决多目标定位问题的潜力.  相似文献   

基于Student′s t分布的不依赖子波最小二乘逆时偏移   总被引：1，自引：0，他引：1       下载免费PDF全文

李庆洋  黄建平  李振春 《地球物理学报》2017,60(12):4790-4800

最小二乘逆时偏移(Least-Squares Reverse Time Migration,LSRTM)与常规偏移相比具有更高的成像分辨率、振幅保真性及均衡性等优势,是当前研究的热点之一.震源子波的估计直接影响LSRTM结果的好坏,在实际情况下考虑到震源子波的空变特性,其估计十分困难.为了消除子波对LSRTM结果的影响,本文发展了基于卷积目标泛函的不依赖子波LSRTM算法.目标泛函由观测记录卷积模拟记录的参考道以及模拟记录卷积观测记录的参考道组成,由于观测子波和模拟子波在目标泛函的两项中同时存在,从而消除了子波的影响.此外,常用的基于L2范数拟合的LSRTM算法对噪声非常敏感,尤其是当地震数据中含有异常值时,常规LSRTM无法得到满意的结果.Student′s t分布相比L2范数具有更好的稳健性,本文将其推广到不依赖子波LSRTM中,提升了算法的稳健性,最后通过理论模型及实际资料试算验证了算法的有效性和对复杂模型的适应性.  相似文献