ODP806井位氧同位素变化记录中轨道倾斜度和轨道偏心度同时出现     

Mull.  RA 陈玲玲 《海洋地质译丛》1997,(2):72-76

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Cloning of a chub metallothionein cDNA and development of competitive RT-PCR of chub metallothionein mRNA as a potential biomarker of heavy metal exposure   总被引：3，自引：0，他引：3  

Hayes RA  Regondi S  Winter MJ  Butler PJ  Agradi E  Taylor EW  Kevin Chipman J 《Marine environmental research》2004,58(2-5):665-669

Metallothionein has been assayed in a range of aquatic animal tissues as an indicator of metal exposure. We sequenced chub (Leuciscus cephalus) metallothionein cDNA which showed over 90% homology to common carp, goldfish and stone loach and 77% homology to rainbow trout sequences for metallothionein. We then used the extended primer method to develop an accurate quantitative competitive RT-PCR assay for metallothionein mRNA. RT-PCR was used to measure metallothionein mRNA in feral chub from a range of field sites, with different levels of heavy metal pollution, in the West Midlands, UK. Measurements were complemented by analysis of liver and gill metallothionein protein by capillary electrophoresis. There was no significant difference in the metallothionein protein levels between fish of different rivers and there was no evidence of elevation of mRNA at the sites of highest metal exposure. The level of metal exposure (e.g. zinc, nickel and cadmium each ranging between 15 and 28 microg/l ) at the pH (7.5-8.5) of these rivers appears insufficient to elevate hepatic or gill metallothionein in chub. A lack of elevation of hepatic metallothionein mRNA in chub exposed to zinc, copper and manganese for 24 h and 10 days in the laboratory also suggests a non-responsiveness of this species.  相似文献   

Phytoremediation of small-scale oil spills in fresh marsh environments: a mesocosm simulation     

Dowty RA  Shaffer GP  Hester MW  Childers GW  Campo FM  Greene MC 《Marine environmental research》2001,52(3):195-211

Research was conducted to assess the impact of oiling on fresh-marsh plant communities and to test the efficacy of techniques that may be used to enhance the bioremediation of crude oil spills in these environments while minimizing secondary anthropogenic impacts. To emulate field conditions, a mesocosm facility was used that houses 120 mesocosm vessels, each of 200-1 capacity. A five-way factorial treatment arrangement was used that included two substrates (inorganic, organic), two nutrient regimes (fertilized, not fertilized), two aeration levels (substrate aeration, no aeration), three oiling concentrations (0-, 5-, 10-1 m(-2) of South Louisiana Sweet Crude oil), and four vascular plant species (Alternanthera philoxeroides, Panicum hemitomon, Phragmites australis, Sagittaria lancifolia, and an unplanted control). Under the 5- and 10-1 m(-2) oiling concentrations, S. lancifolia displayed a short-term response of increased productivity, whereas P. hemitomon had the highest biomass production and photosynthetic rates at the end of the 18-month experiment. Overall plant growth and productivity, as well as oil degradation, were significantly higher in the inorganic substrate, indicating that biodegradation of oil spills in organic substrates may require a longer time period. Time-released fertilizer also stimulated plant productivity and resulted in higher soil respiratory quotients, suggestive of greater microbial activity, particularly in aerated mesocosms. The amount of oil remaining after 18 months was lowest in aerated and fertilized mesocosms containing either P. hemitomon or S. lancifolia and a substrate of low organic matter content.  相似文献   

Sediment oxygen profiles in a super-oxygenated antarctic lake     

Wharton RA  Meyer MA  McKay CP  Mancinelli RL  Simmons GM 《Limnology and oceanography》1994,39(4):839-853

Perennially ice-covered lakes are found in the McMurdo Dry Valleys of southern Victoria Land, Antarctica. In contrast to temperate lakes that have diurnal photic periods, antarctic (and arctic) lakes have a yearly photic period. An unusual feature of the antarctic lakes is the occurrence of O2 at supersaturated levels in certain portions of the water column. Here we report the first sediment O2 profiles obtained using a microelectrode from a perennially ice-covered antarctic lake. Sediment cores collected in January and October 1987 from Lake Hoare in Taylor Valley show oxygenation down to 15, and in some cases, 25 cm. The oxygenation of sediments several centimeters below the sediment-water interface is atypical for lake sediments and may be characteristic of perennially ice-covered lakes. There is a significant difference between the observed January and October sediment O2 profiles. Several explanations may account for the difference, including seasonality. A time-dependent model is presented which tests the feasibility of a seasonal cycle resulting from the long photoperiod and benthic primary production in sediments overlain by a highly oxygenated water column.  相似文献   

Regional trends in crude birth,death, and natural increase rates in Russia and the USSR: 1897-1989     

Lewis RA  Rowland RH 《Post-Soviet geography》1995,36(10):617-643

"This paper establishes and discusses briefly regional patterns and trends in crude birth, death, and natural increase rates in Russia and the USSR from the turn of the century to 1989. The study is based on a comparable regional framework and placed in the context of the demographic transition theory. It discusses sources, collection, and quality of data, as well as necessary estimating procedures. An attempt also is made to examine briefly regional age-standardized rates."  相似文献   

地面地震层析技术在金属矿勘查中的试验研究   总被引：6，自引：0，他引：6  

徐明才  高景华  荣立新  柴铭涛  刘建勋  吕庆田  史大年 《物探与化探》2005,29(4):299-303

由于金属矿区地质构造的复杂性和复杂的地表条件, 适合于探测层状介质的地震反射方法技术在金属矿勘查中的应用受到了限制。为提高地震记录的横向分辨率, 探测复杂的地质构造及隐伏岩体等, 需研究相应的地震方法技术, 地面地震层析技术在金属矿勘查中的试验研究就是为解决上述问题而开展的。本文就非线性地面地震层析技术的基本原理进行了阐述, 并就该方法在金属矿勘查中的试验效果进行了讨论。  相似文献   

微量物质对海洋的大气输入     

Duce  RA 李诗明 《气象科技》1997,(1):9-19

在过去的十年中，显而易见，大气是许多自然物质和污染物从大陆输送到海洋的重要途径。这些物质的大气输入对海洋生物过程和海洋化学循环有正或负的影响。例如：很明显，大气是许多区域的重要营养成分如铁，氮等的重要输送途径。在本报告中，我们评价了这些地区的期的数据，发展向海洋的微量元素，矿物气溶胶，含氮物质合成有机物的大气通量的全球范围的估算值；比较了这些物质通过大气和河流输入的海洋比率。  相似文献   

内蒙古准苏吉花斑岩型钼矿及外围反射地震探测     

徐明才  周建勇  柴铭涛  高景华  刘建勋  张保卫 《物探与化探》2016,(4):639-647

内蒙古准苏吉花斑岩型钼矿床是一个中型金属矿床,目前勘查区内还没有较深的钻孔资料。为探测深部隐伏金属矿和控矿构造及深部地质结构,在内蒙古准苏吉花钼矿区及其外围开展了高精度反射地震测量。该反射地震采用2台套大功率可控震源激发,5 m道间距,960道接收,80次覆盖的工作方法,获得了能清晰反映深部地质结构和构造的高精度反射地震剖面。在该剖面上,能够清楚地解释测区导矿和控矿构造及隐伏岩体分布及燕山期与华力西期岩体的交切关系,并据此讨论了地壳深部流体运移的路径和动力过程,为在该区寻找深部隐伏金属矿指明了新的找矿靶区。  相似文献   

哈拉湖地区天然气水合物地震探测技术试验     

徐明才  哈立洋  王小江  柴铭涛  刘建勋  王广科  张保卫  李培  王凯  高景华 《物探与化探》2016,(4):667-674

哈拉湖位于青藏高原,在该区开展的地质调查、音频大地电磁测深和地球化学调查结果表明,该区具有良好的天然气水合物找矿前景。为寻找天然气水合物,在该区开展了高精度反射地震试验。反射地震采用1 200道接收,道间距2 m,偏移距1 m,炮间距8 m,覆盖次数150次,排列中间激发的观测系统,每道采用6个60 Hz检波器单点组合接收;采样间隔0.5 ms,记录长度2 s,宽频带采集;激发震源为大型车载可控震源。采用该工作方法得到的地震剖面信噪比和分辨率较高,构造形态特征明显。根据试验区地形地貌和地震剖面上反映的永冻土层厚度、断裂构造和高速层分布,结合其他资料,确定了验证孔位。  相似文献   

国际地磁参考场1991年修订版：国际地磁学及超高层大气物理学协会（IA …     

兰格.  RA  李建国 《物探化探译丛》1993,(3):35-40

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