A geochemical approach to constraining the formation of glassy fallout debris from nuclear tests     

Chlo??E.?BonamiciEmail author  William?S.?Kinman  John?H.?Fournelle  Mindy?M.?Zimmer  Anthony?D.?Pollington  Kirk?D.?Rector 《Contributions to Mineralogy and Petrology》2017,172(1):2

Glassy nuclear fallout debris from near-surface nuclear tests is fundamentally reprocessed earth material. A geochemical approach to analysis of glassy fallout is uniquely suited to determine the means of reprocessing and shed light on the mechanisms of fallout formation. An improved understanding of fallout formation is of interest both for its potential to guide post-detonation nuclear forensic investigations and in the context of possible affinities between glassy debris and other glasses generated by high-energy natural events, such as meteorite impacts and lightning strikes. This study presents a large major-element compositional dataset for glasses within aerodynamic fallout from the Trinity nuclear test (“trinitite”) and a geochemically based analysis of the glass compositional trends. Silica-rich and alkali-rich trinitite glasses show compositions and textures consistent with formation through melting of individual mineral grains—quartz and alkali feldspar, respectively—from the test-site sediment. The volumetrically dominant glass phase—called the CaMgFe glass—shows extreme major-element compositional variability. Compositional trends in the CaMgFe glass are most consistent with formation through volatility-controlled condensation from compositionally heterogeneous plasma. Radioactivity occurs only in CaMgFe glass, indicating that co-condensation of evaporated bulk ground material and trace device material was the main mechanism of radioisotope incorporation into trinitite. CaMgFe trinitite glasses overlap compositionally with basalts, rhyolites, fulgurites, tektites, and microtektites but display greater compositional diversity than all of these naturally formed glasses. Indeed, the most refractory CaMgFe glasses compositionally resemble early solar system condensates—specifically, CAIs.  相似文献   

US tornado fatalities in motor vehicles (1991–2015)     

Marius?J.?PaulikasEmail author  Thomas?W.?Schmidlin 《Natural Hazards》2017,87(1):121-143

Motor vehicles historically have been dangerous locations to shelter in during tornado events. Throughout the twentieth century, motor vehicle design has become safer while tornado forecasting has become better understood. Despite such advances, tornado fatalities in motor vehicles still occur today, and some events periodically result in high numbers of deaths (e.g., ten motor vehicle occupants were killed by a single tornado in Garland, Texas, in 2015). We seek to examine all US tornado-induced motor vehicle fatalities documented between 1991 and 2015. Our findings indicate that motor vehicle fatalities have not significantly changed during this study period. We attribute annual fatality totals to persons lacking awareness of impending dangers coupled with numbers of significant tornado events for a given year. We find most fatalities result when vehicles are lofted or passengers are ejected, and this most typically occurs at the EF3–EF5 intensity thresholds. Fatalities that occur at weaker tornado winds (EF0–EF2) are most often attributed to collapsing debris (mostly trees) on vehicles. Spatially, motor vehicle fatalities are greatest in the Deep South and southern Great Plains regions where overall tornado and nighttime tornado frequencies are greatest. Some of the largest motor vehicle fatality events have resulted from tornadoes not being distinctly visible to motorists; such events have been characterized by tornadoes occurring at night or by tornadoes not appearing as “classic funnels.”  相似文献   

Organic-walled Microfossils from the Early Middle Cambrian sediments of the Holy Cross Mountains, Poland: Possible Implications for Sedimentary Environment in the SE Margin of the Baltica     

Marta B?K  Lucyna NATKANIEC-NOWAK  Beata NAGLIK  Krzysztof B?K  Pawe? DULEMBA 《《地质学报》英文版》2017,91(1):39-50

An association of organic-walled microfossils consisting of filamentous cyanobacteria, algal coenobia and acanthomorphic acritarch have been documented from non-calcareous claystones and mudstones of the Pepper Mountains Shale Formation(PMSF), located in its stratotype area in the Pepper Mountains, which are part of the Holy Cross Mountains in Poland. These sediments represent the oldest strata of the ?ysogóry Unit, deposited on the edge of the East European Craton(Baltica). Non-branched, ribbon-like and thread-like cyanobacteria trichomes exhibit morphological similarities to families Nostocaceae and Oscillatoriaceae. Cells assembled in rounded to irregular clusters of monospecific agglomerations represent multicellular algal coenobia, attributed to the family Scenedesmaceae. The co-occurrence of acritarchs belonging to species as Eliasum llaniscum, Cristallinium ovillense and Estiastra minima indicates that the studied material corresponds to the lower Middle Cambrian. Deposition of the PMSF took place in shallow marine environment, influenced by periodical freshwater inputs. The varying degree of coloration of organic-walled microfossils is interpreted in this study as factor indication of possible different source of their derivation. Dark brown walls of cells assembled in algal coenobia might have sustained previous humification in humid, terrestrial environments, which preceded their river transport into the sea together with nutrients, causing occasional blooms of cyanobacteria in the coastal environment and the final deposition of both groups of organisms in marine deposits.  相似文献   

Permo–Triassic and Liassic Tethyan Oceanic Tracts within the Pontide Belt Along the Southern Margin of Eurasia, Northern Anatolia     

E. SARIFAKIOGLU  Y. DILEK  M. SEVIN  ?. PEHLIVAN  ?. KANDEMIR  A. M?LLER  T. BAYANOVA  I. UYSAL  M. KELES 《《地质学报》英文版》2017,91(Z1):33-34

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Biomonitoring of organochlorine compounds and trace metals along the Eastern Adriatic coast (Croatia) using Mytilus galloprovincialis     

Zorana Kljakovi?-Gašpi?  Snje?ana Herceg-Romani? 《Marine pollution bulletin》2010,60(10):1879-1889

The paper presents the results of monitoring trace organic contaminants (17 PCBs and 7 OCPs) and 6 trace metals (Cd, Cr, Cu, Hg, Pb and Zn) in the coastal waters of the eastern Adriatic in 2006 using Mytilus galloprovincialis as indicator species. OCPs were found in all samples (0.07-14.3 ng g⁻¹ d.wt.), while in positive samples concentrations of PCBs ranged between 0.16 and 20.5 ng g⁻¹ d.wt. The α-HCH/γ-HCH and DDE/DDT ratios indicated recent input of γ-HCH and DDT. Spatial distributions of HCB, PCBs, DDTs and Hg were significantly correlated with population density. Although elevated concentrations of all trace metals and organic contaminants were recorded in the densely populated and industrialized areas, overall data point to relatively low level of contamination of the eastern Adriatic coast. Evaluation of the risks to human health associated with consumption of the mussels suggested that there is no health risk for moderate shellfish consumers.  相似文献   

Urban environments as habitats for rare aquatic species: The case of leeches (Euhirudinea, Clitellata) in Warsaw freshwaters     

Pawe? Koperski 《Limnologica》2010,40(3):233-240

Reduced biological diversity in freshwater habitats situated in urban areas has been discussed in numerous studies. Certain municipal areas, however, can help save animal diversity of freshwater invertebrates. In the present study animals were collected or observed alive in 13 freshwater environments localized in Warsaw - the second largest city of Central Europe - in a densely populated, urban building complex close to the city, and also in suburban areas. Leech assemblages in all the environments under observation were numerically dominated by a few common species, but on the whole 19 species were collected or observed. The populations of six rare leech species inhabit both flowing and standing waters in Warsaw. Five of these species are on the Polish Red List of Species and one is strictly protected. The shallow Lake Powsinkowskie is the richest freshwater environment in the studied area in terms of species richness and rarity and also one of the richest lakes in Poland. Taxonomic diversity in the environments under study seems not to be directly related to the size of the water body or the level of degradation but rather to the habitat complexity, especially the diversity of the bottom in littoral zone. Certain freshwater habitats located inside this great urban complex still create good conditions for rare, highly specialized species.  相似文献   

Phytoplankton based assessment of the ecological status of four shallow lakes (Eastern Poland) according to Water Framework Directive - a comparison of approaches   总被引：2，自引：0，他引：2  

Agnieszka Pasztaleniec  Ma?gorzata Poniewozik 《Limnologica》2010,40(3):251-3828

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地震废墟中人体心脏电场信号的提取          下载免费PDF全文

鲁霞  王绪本  高嵩 《地震工程学报》2010,32(1):25-29

基于人体心脏电场信号的生命探测仪是目前最先进的生命探测仪,其困难之处在于从地震废墟中提取微弱的心脏电场信号。本文主要分析地震废墟中可能出现的对人体电场有干扰的信号情况,提出如何接收废墟中微弱的超低频心脏电场信号,并根据人体心脏电场的特征设计特殊滤波器滤除干扰信号,只保留因人体心脏跳动而产生的360度扩展的超低频非均匀电场。  相似文献   

汶川8.0级地震前地震空间相关长度变化特征   总被引：3，自引：3，他引：0       下载免费PDF全文

荣代潞  李亚荣 《地震工程学报》2010,32(1):54-58

分析了汶川8.0级地震前的地震空间长度的时空演变。在计算空间相关长度过程中采用长轴与孕震区主要断裂走向一致的椭圆型空间窗,并设计了优化程序。在本次特大地震前观测到了增长的地震空间相关长度。利用合成地震目录对结果进行了显著性检验,结果否定了零假设,表明观察到的模型不是由随机数据干扰造成的,这一观点的置信水平被证实为93.9%。  相似文献   

兰州台阵响应函数及不同方位小地震事件FK分析结果          下载免费PDF全文

沈旭章  梅秀苹  张淑珍  秦满中 《地震工程学报》2010,32(1):59-64

计算了兰州台阵不同频率的台阵响应函数,对台阵附近不同方位的4个小震进行了FK分析。结果显示兰州台阵2 Hz以下的台阵响应函数在原点附近呈现出对称的单主峰图样,而高于2Hz时台阵响应函数出现较多旁瓣,表明该台阵对于2 Hz以下的信号具有较好的分辨能力。小震的FK分析结果表明,根据甘肃省地震局地震目录和IASP91速度模型计算得到P波方位角和慢度与FK分析的结果总体上比较一致,但也存在一定差别,这种差别可能由所使用的理论模型和当地模型有差别以及未做台阵校正所引起。  相似文献