Palaeobotanical evidence of wildfires in the Late Palaeozoic of South America – Early Permian, Rio Bonito Formation, Paraná Basin, Rio Grande do Sul, Brazil     

Andr Jasper  Dieter Uhl  Margot Guerra-Sommer  Volker Mosbrugger 《Journal of South American Earth Sciences》2008,26(4):435-444

Fossil charcoal, as direct evidence of palaeowildfires, has repeatedly been reported from several plant-bearing deposits from the Late Palaeozoic of the Northern Hemisphere. In contrast charcoal reports from the Late Palaeozoic deposits of the Southern Hemisphere are relatively rare in comparison to the Northern Hemisphere. Although the presence of pyrogenic coal macerals has repeatedly been reported from Late Palaeozoic coals from South America, no detailed anatomical investigations of such material have been published so far. Here is presented an anatomical analysis of charcoal originating from Early Permian sediments of the Quitéria Outcrop, Rio Bonito Formation, Paraná Basin, located in the central-eastern portion of Rio Grande do Sul, Brazil. This charcoal comes from two different coaly facies, and it was possible to scrutinize between three types, based on anatomical characters of the charcoal. Two of these charcoal types can be correlated to gymnosperm woods, and the other type corresponds to strongly permineralized bark with characteristic features of lycopsids. The presence of charcoal in different facies, ranging from parautochtonous to allochtonous origin, indicates that different vegetation types, i.e. plants which grew under wet conditions in the lowland as well as in the more dry hinterland, have experienced wildfires. Taking into account previous petrographic and lithological analyses from the facies in which the charcoal occurs and from the conditions of the wood and bark fragments, it was possible to speculate that the intensity of such wildfires most probably corresponds to forest-crown fires. Moreover, it is possible to state that wildfires have been a more or less common element in distinct Late Palaeozoic terrestrial ecosystems in the South American part of Gondwana. The data support previous assumptions on the occurrence of wildfires in the Early Permian of the Paraná Basin which were based solely on coal-petrographic data.  相似文献   

存储式岩心定向取心技术应用研究          下载免费PDF全文

周策  陈文俊  石绍云  汤国起 《探矿工程》2008,35(7):77-79

采用岩心定向取心技术不仅可以迅速而方便地确定地下矿层和结构面的产状,而且还可以判断矿层的走向,了解地层倾向,预测钻孔弯曲的趋势。介绍了存储式岩心定向取心原理、关键技术问题、器具构成、技术参数以及现场应用情况。  相似文献   

舟山国家石油储备基地堆载预压加固效果分析   总被引：5，自引：0，他引：5  

朱向荣  李振  王金昌 《岩土力学》2008,29(4):881-886

介绍了舟山国家石油储备基地试验区软基堆载预压大型现场试验结果,根据现场试验测得的数据,分析了软土地基堆载预压下沉降变化规律、分层沉降变化规律、深层土体位移变化规律、超静孔隙水压力变化规律,进一步探讨了根据应力和应变分析得到的地基固结性状,其中通过应变分析得到适用于储备基地的沉降经验系数m。结果表明,打设塑料排水板结合堆载预压处理软弱地基具有良好的效果。  相似文献   

分光光度法测定海洋河弧菌510脂多糖     

张运涛  顾谦群  方玉春  吕元萌  管华诗 《中国海洋大学学报(自然科学版)》2003,33(3):355-360

本文研究了直接测定海洋河弧菌 (vibrio fluvailis) 5 10脂多糖的分光光度法。利用 1,9-二甲基亚甲蓝 (DMB) ,在适当条件下同脂多糖发生染色反应 ,在 5 5 0 nm波长下 ,反应体系的吸光值同脂多糖含量呈线性相关。相关系数为 0 .9993,最低检出限为 10 μg/m L,相对标准偏差为 1.6 2 ,平均回收率为 (10 5± 2 .18) %。  相似文献   

一种计算台风风场的方法     

陈孔沫 《热带海洋学报》1994,(2)

揭示Ｒａｎｋｉｎｅ涡风场模式和Ｊｅｌｅｓｎｉａｎｓｋｉ风场模式之间的联系，并设计了一种台风风场分布模式，它的风速分布曲线落在Ｊｅｌｅｓｎｉａｎｓｋｉ和Ｒａｎｋｉｎｅ涡两个风场模式的风速分布曲线之间，具有一个既优于Ｊｅｌｅｓｎｉａｎｓｋｉ又优于Ｒａｎｋｉｎｅ涡的风速衰减速率，因此它同时克服了Ｒａｎｋｉｎｅ涡模式计算风速偏小和Ｊｅｌｅｓｎｉａｎｓｋｉ模式计算风速偏大的缺点，以一种比较合理的变化趋势向远方衰减，成为一个比较切合实际的台风风场分布模式。同时，文中提出的移行台风风场计算方法对宫崎正卫、上野武夫和Ｊｅｌｅｓｎｉａｎｓｋｉ模式都有一定的改进。  相似文献   

东亚温带气旋及其长期预报（二）：预报应用分析     

战淑芸  杨淑瑞 《海洋预报》1995,12(1):26-30

本文以赤道东太平洋海温作为主导因子，分析其与东亚温带气旋的关系。得出：高海温多气旋，低海温少气旋的对应关系较为明显。并进一步对不符合这种主要关系的年份从环流型。下垫面海温等作了分类鉴别分析。  相似文献   

在各类天气系统影响下石臼港沿岸波浪场的分布     

黄爱军  李观金 《海洋预报》1994,11(3):15-25

本文查阅了从１９７３－１９８５，１３年的历史资料，对石臼港沿岸波浪场进行了详细的分类、统计分析和计算，提出了各类较强天气系统影响石（即指石臼港）的极端区域，同时获得了石港沿岸各类天气系统影响下的波浪分布特点以及波高计算式，为保障石港的生产及港口建设为石港的波了提供了有益的分析数据和预报手段。  相似文献   

Marine Ecology - A Century of Changes     

Rupert  Riedl 《Marine Ecology》1980,1(1):3-46

Abstract. The major changes within the concepts of marine ecology are investigated, with the aim to design this new journal's scientific format. Four phases of marine sciences are distinguished: the phase of seafarers, of oceanographic expeditions, of marine stations, and of field research. The changes in the latter two are discussed in detail. The changes are described as occurring along three axes. First, as a movement towards the object; accomplished by fieldwork, scientific diving, remote controlled equipment, and by underwater experimentation. Second, the cooperation between several disciplines that led towards bridging gaps. And lastly, how the discovery of unifying principles in ecology (the development of an ecological theory) led the approach in marine ecology towards increasing complexity.  相似文献   

Estradiol and estriol suppress CYP1A expression in rainbow trout primary hepatocytes     

Elskus AA 《Marine environmental research》2004,58(2-5):463-467

Hepatic levels of the pollutant inducible enzyme, CYP1A, are strongly suppressed in spawning female fish, a phenomenon attributed to high plasma levels of the female sex steroid hormone, estradiol. To evaluate the contribution of estrogen metabolites to estradiol-mediated CYP1A regulation, we treated primary hepatocytes isolated from juvenile rainbow trout (Oncorhynchus mykiss) with vehicle, 17beta-estradiol, or the estrogen metabolite, estriol, alone and in combination with each other and with the potent CYP1A inducer, benzo[a]pyrene (B[a]P). We found dose-dependent suppression of B[a]P-induced CYP1A activity by both steroids relative to controls. At 10(-7) M doses, estradiol and estriol suppressed B[a]P-induced CYP1A activity by 3- and 2-fold, respectively. Although not statistically significant, mean basal CYP1A activity levels were 15- and 13-fold lower in estradiol and estriol treated hepatocytes, respectively, relative to vehicle treated controls. Combining doses of estradiol and estriol failed to produce synergistic suppression of either basal or B[a]P-induced CYP1A activity relative to treatment with either steroid alone. The observed suppression is well below the often strong suppression observed in spawning female fish. We conclude that factors in addition to estradiol and estriol are likely involved in producing sexual dimorphism in CYP1A expression observed in spawning fish.  相似文献   

一种浅海锚泊测流浮标系统的实验     

李文湑  孙寿昌 《海洋科学集刊》1984,(23):43-50

早在五十年代,海洋科技工作者已开始利用浮标布设海洋调查仪器,进行海上观测的试验工作。目前被采用的浮标系统,大体有三种类型:(1)锚泊浮标系统,利用各类自含式海洋调査仪器进行测量,定期收回资料;(2)遥测浮标系统,利用无线电遥控和收发各种海洋观测数据;(3)漂移浮标系统,利用浮标本身的漂移,进行海流和其他要素的观测。本文主要介绍浅海锚泊浮标系统的设计和使用情况。 对锚泊浮标系统的研究和实验,许多国家已做了大量有成效的工作。目前关于浮标的设计和锚泊方法尚无統一意见,但是可以看出,大多趋向于采用水下浮标张缆锚泊。这种方法使得浮标系统比起遥测浮标系统来,较为轻小、经济、方便,适合于进行多站同步观测。国外在海洋调查中经常利用这种系统作较长期的海流观测。 我所在六十年代初就已开始了锚泊浮标系统的研究、实验,1964年进行了新的研究设计工作,并在“全国海洋仪器会战”期间,完成了整套系统的计算设计与海上实验,经过鉴定,建议作小批量生产。 近年来,国家海洋局第一海洋研究所、中国科学院南海海洋研究所利用该浮标系统作过多次海上试用,取得了海流长期观测资料,初步考验了该系统的性能。我们最近又对某些部件作了一定的改进,并进行了海上实验。但是,实验也表明:此方法不宜在渔场区和台风盛行季节使用,因易被渔网拖损和丢失。现综合报告如下。  相似文献