不同pH处理对菹草(Potamogeton crispus L.)Cr⁶⁺毒害效应的影响     

黄敏  施国新  夏海威  吴娟  乔绪强  汪鹏合  陈霖 《湖泊科学》2014,26(4):607-615

对Cr⁶⁺胁迫条件下不同pH处理对菹草无菌苗元素、光合色素、活性氧、丙二醛、抗氧化酶、脯氨酸(Pro)及多胺(PAs)含量的影响进行研究,以探讨不同pH处理影响水生植物Cr⁶⁺毒害效应的机制.结果表明:(1)偏酸性pH处理加剧菹草对铬的蓄积,而pH为7.0时Cr⁶⁺胁迫所造成的矿质元素失衡有所减弱;(2)Cr⁶⁺胁迫下pH为6.0~8.0的处理延缓了菹草的失绿症状,促进了光合色素的合成;(3)Cr⁶⁺胁迫下菹草超氧化物歧化酶、过氧化氢酶的活性在pH为6.0和7.0的处理组诱导程度最小;(4)Cr⁶⁺胁迫下pH为6.0和7.0处理的菹草Pro含量显著提高;(5)pH为4.0和5.0的处理使腐胺(Put)含量显著提高,而pH为6.0和7.0的处理则促进亚精胺(Spd)含量及游离态(Spd+Spm)/Put比值上升,精胺(Spm)含量总体趋势为随pH值升高而逐步上升,仅在pH为4.0和5.0的处理组中低于Cr⁶⁺胁迫对照组.因此,pH条件可影响菹草对铬及营养元素的积累,抗氧化酶、Pro、PAs代谢等生理生化过程,导致铬毒性效应差异.在pH为6.0~7.0的范围内,菹草能调节抗氧化酶系统,较有效地清除体内活性氧,提高机体中Pro、PAs含量及游离态(Spd+Spm)/Put比值,减轻膜系统脂质过氧化,维持机体内矿质元素平衡,致使毒性效应达到最小程度.  相似文献   

安徽淮南地区明龙山-上窑断裂第四纪活动特征     

方良好  疏鹏  路硕  郑颖平  林承灏 《震灾防御技术》2017,12(3):469-479

明龙山-上窑断裂是一条逆走滑性质的第四纪活动断裂,长约68km,走向300°-315°。本文在卫星影像解译的基础上,通过野外调查,确定了该断裂的几何展布和分段特征,初步将断裂分为明龙山、上窑、凤阳山3条次级断裂段。通过对断裂经过处的采石场进行详细追索,我们对典型断层剖面进行了描述并采集了断层泥ESR样品,得到的测年结果为（243±24）ka和（126±15）ka,由于淮南地区是典型的中等强度地震活动区,断层晚第四纪以来活动强度较弱,这些测年结果虽不能代表断层最后一次微弱活动的时代,但可以确定断层最后一次强烈活动时代为中更新世晚期至晚更新世早期。结合前人对1831年凤台M_S 6?级地震极震区位置、等震线形态研究及本文对极震区附近断裂展布和活动性的对比分析,我们认为明龙山-上窑断裂为本次地震发震构造的可能性最大。  相似文献   

Luminescence dating of glaciolacustrine silt in overdeepened basin fills beyond the last interglacial     

《Quaternary Geochronology》2017

OSL and IRSL dating are applied to samples from a 152 m-long drill core to constrain the timing of three glaciolacustrine depositional periods within the infill of an overdeepened bedrock trough in the Lower Glatt valley, N Switzerland. The characterisation of the dose-response suggests that the polymineral IRSL₅₀ and pIRIR_180/225 signals are close to saturation, while quartz OSL ages are within the range of reliable dating. The demarcation of the upper quartz OSL dating limit, however, remains challenging. Dose-recovery tests performed with long storage periods were used to investigate the reliability of the high region of the dose-response curve. They suggest an upper limit for reliable dating of ∼400 Gy for these samples, which was considerably lower than the commonly used 2D₀ criterion. Lifetimes were calculated for the quartz OSL and the thermal stability of the signal is not considered as problematic for the determined ages. Allowing for a contribution from inherited dose due to partial bleaching, places the infill of the overdeepened valley within the penultimate glacial cycle (MIS6).  相似文献   

Diurnal,Seasonal, and Vertical Variability in Carbon Monoxide Levels at a Semi‐Urban Site in India     

《洁净——土壤、空气、水》2017,45(5)

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Differences between Humic Substances from Riverine,Estuarine, and Marine Environments Observed by Fluorescence Spectroscopy     

Valdemar I. Esteves  Armando C. Duarte 《洁净——土壤、空气、水》2001,28(7):359-363

Sixteen samples of fulvic acids and XAD‐4 fractions of riverine, estuarine, coastal, and open ocean origin have been studied by emission and synchronous molecular fluorescence spectroscopy. Certain features of the molecular fluorescence are related to the nature, the content, and the origin of those aquatic humic substances (HS). Riverine HS appear several times richer in fluorophores than marine HS, which can be well observed by emission fluorescence spectroscopy. Synchronous‐scan spectra of fulvic acids and of XAD‐4 fractions from the aquatic environments studied, emphasized the quality differences of their fluorophores. These features are useful as tracers of humic substances related with their natural environment source or even with their anthropogenic origin.  相似文献   

Zielvorgaben für Pflanzenschutzmittelwirkstoffe und andere Schadstoffe in Oberflächengewässern     

Jutta Jahnel  Christian Zwiener  Thomas J. Gremm  Gudrun Abbt‐Braun  Fritz H. Frimmel  Carola Kussatz  Dieter Schudoma  Werner Rocker 《洁净——土壤、空气、水》2001,29(4):246-253

Quality Targets for Pesticides and Other Pollutants in Surface Waters Surface waters are not only adversely affected by industrial and municipal wastewaters but also by diffuse sources. For the control of the ecological water quality, so‐called quality targets are set. The quality targets are threshold concentrations for hazardous substances related to the protected goods like water ecosystems, drinking water supply, sediments, or fishing. In this paper, quality targets for the protection of aquatic life in surface waters were derived on the basis of a concept developed by the International Commission for the Protection of the Rhine (Internationale Kommission zum Schutze des Rheins – IKSR). The quality targets for the selected hazardous substances, which mainly belong to the chemical class of pesticides, were calculated using ecotoxicological results for species of bacteria, algae, fish, and small crustaceans, as the four trophic standards of the water ecosystem. In cooperation with the Federal Environmental Agency (Umweltbundesamt – UBA) the effect data were taken from ecotoxicological data bases. According to the concept of the IKSR, the lowest test result for the most sensitive species was multiplied by an assessment factor. This proceeding concerns the difficulty in describing the complex interactions in water ecosystems with toxicity data of single laboratory experiments for a few organisms. For seven pesticides quality targets below 0.1 μg/L were proposed. These results show that the ecotoxicologically based quality targets might be even lower than the limit values for pesticides in drinking water of 0.1 μg/L. But for most of the substances the determined values are significantly higher. The great concentration range of quality targets demonstrates distinctly that one standard concentration for all pesticides could not be given with regard to the different effects on aquatic organisms.  相似文献   

Anthropogenic Eutrophication and Red Tide Outbreak in Lacustrine Systems of the Kashmir Himalaya     

M. A. Kahn 《洁净——土壤、空气、水》2000,28(2):95-101

Red tide, a recurrent phenomenon has become conspicuous in several Kashmir lake ecosystems since 1991. The responsible organism (Euglena pedunculata), a rare flagellate rediscovered in the Kashmir Himalaya (Khan 1993) caused first and unprecedented red tide outbreak, constituting a maximum of 96% of resident numerical phytoplankton density in Dal Lake. At present, conflicting hypotheses exist on the generation of causal assemblage(s) imparting redness to waters: Jeeji Bai (1991) linked its origin to acid precipitation – a fallout of burning oil‐fields during the Gulf War – whilst Khan (1993) holds local factor(s) responsible. Field/experimental studies support the latter contention that the influx of untreated sewage, in unison with warm temperatures, high levels of PhAR, iron and interruption to hydrological flow‐pattern together with absence/or reduction in grazing activity created conducive environmental milieu for red tide outbreak. Dal Lake “red tide” drifted the bloom‐inoculum to other waters, including Lake Wular, where additional ecological niches were carved out, threatening the aesthetic value and biological diversity of Kashmir lakes. Ecological monitoring indicates frequent seasonal red tide occurrence in Dal Lake (including summer‐autumn event of 1998) which testifies its unabated eutrophication status. Further studies are needed on ecological adaptability and biogeographic distribution of this rare and unique red tide‐causing flagellate.  相似文献   

Characterization of AOX by Fractionation Analysis and Size‐exclusion Chromatography     

Th. J. Gremm  F. H. Frimmel 《洁净——土壤、空气、水》2000,28(4):202-211

A characterization method for AOX in surface water samples was developed and tested. The method involves fractionation using a hydrophobic C18 resin and a weak anionic exchange resin and allows the fractionation of the AOX pool of surface water samples into four fractions: (1) hydrophilic acidic, (2) hydrophilic non‐acidic, (3) hydrophobic acidic, and (4) hydrophobic non‐acidic. The adsorption analysis was verified with AOX‐relevant model compounds and was applied to characterize the AOX pool of a stream sample from the Moskva river (Russia). In addition to the fractionation analysis, size‐exclusion chromatography was used to characterize the AOX pool of the sample studied. Hydrophilic acids made up the major fraction of the AOX pool (55 %). Among this fraction chlorinated high‐molecular acids (humic substances) made up the main fraction (35 %).  相似文献   

Analyses of iron oxide assemblages within Namib dune sediments using high field remanence measurements (9 T) and Mössbauer analysis     

John Walden  Kevin H. White  Susan H. Kilcoyne  Phillip M. Bentley 《第四纪科学杂志》2000,15(2):185-195

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厚壳贻贝(Mytilus coruscus)足丝蛋白mcofp3和mcofp6的cDNA克隆及序列分析          下载免费PDF全文

廖智  鲁涛  李楠楠  徐田军  王日昕  石戈 《海洋与湖沼》2010,41(5):739-747

通过设计特异性引物,采用PCR扩增的方法对厚壳贻贝足腺细胞cDNA文库进行筛选,共克隆得到14条厚壳贻贝mcofp3的cDNA序列和8条mcofp6的cDNA序列,并对其基因序列及推导的氨基酸序列进行了序列比对和变异位点初步分析。结果表明,14条mcofp3cDNA序列分属于厚壳贻贝mcofp3家族的两个亚家族,其成熟肽序列变异相对活跃;而8条mcofp6 cDNA序列并无明显的亚家族划分,序列相对保守。本次实验所获得的mcofp cDNA序列初步显示了厚壳贻贝足丝蛋白家族基因的分子多样性,为将来深入了解厚壳贻贝足丝蛋白的分子多样性机制以及在此基础上开发相关的新型生物黏附剂奠定了基础。  相似文献