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981.
Dry deposition and air concentration samples were collected from July 2004 to May 2005 at a suburban site in Turkey. A water surface sampler (WSS) was used to measure directly the dry deposition flux of particulate polychlorinated biphenyls (PCBs) while a high volume air sampler (HVAS) was employed to collect air samples. Particulate PCB concentrations accounted for 15% of total PCBs (gas + particle phase) at the site. The overall particulate phase PCB flux ranged from 2 to 160 ng m− 2 d− 1 with an average of 46.3 ± 40.6 ng m− 2 d− 1. Forty one PCB congeners were targeted in the samples while twenty one congeners were found to be higher than detection limits in deposition samples. Fluxes for homolog groups ranged between 0.9 (7-CBs) and 21.0 (3-CBs) ng m− 2 d− 1. Measured dry deposition fluxes were lower than the ones usually reported for urban sites. Average PCB dry deposition velocity, calculated using flux values and concurrently measured atmospheric concentrations, was 1.26 ± 1.86 cm s− 1 depended on size distribution of particles, atmospheric PCB concentrations and meteorological conditions. 相似文献
982.
The Shatter Belt and the European Core - A Geopolitical Discussion on the Untypical Case of Slovenia 总被引:1,自引:0,他引:1
Anton Gosar 《GeoJournal》2000,52(2):107-117
Europe in general is in a great state of change. States uniting with difficulty, states collapsing in pain, newly freed states struggling for new political, economic, and social identities - it is a region in a true transition. The paper is focussing primarily on the European Shatter Belt, formerly known as Eastern Europe. This is in fact a subset of new and old nation-states in the region of Central and Eastern Europe or, to use an older, but increasingly popular term, Mitteleuropa (Ruppert, 1997). Mitteleuropa is reemerging from the commotion resulting from the collapse of the old political order - communism. Our focus in this presentation is on personal experiences and observations. We will note the progress and positive dimensions of the change (transition) in the light of Europe's and NATO expansion. We will address the issues at two scales- at the international/national level and then, at the level of a Slovenian case study. This will enable us to discuss the natural system of the process of enlargement and incorporate supporting material of geographical, historical and social nature as envisioned by Hartshorne. Since the collapse of communism, the region has experienced some serious traumas that vary in intensity across the region. Probably the greatest pain has been experienced in the former Yugoslavia - an estimated 150,000 have perished and about 2.5 millions have been displaced within and outside the country. Chaos still exists despite the protectorate arrangement in Bosnia. The hot spot Kosovo has yet to be calmed down. In parts of the region economic pain has been considerable. Every state of Mitteleuropa experienced absolute economic decline from 1990–1995; high inflation rates, increased economic inequality, high levels of poverty, increase of crime and more. Economic and psychological stress effect demographic processes. Things have partly changed to the better in the most recent years. The adoption of capitalism and a democratic political system has been painful, disorienting, and is still in progress. The democratization process varies considerably across the region and in some states is in jeopardy. Reformed communist parties had staged a restoration in nearly all of the states - in some winning the control of the government, in others gaining strong and influential positions, or both. But, two major processes promise future democracy, rule of law, wealth and stability in general. This is the decision of the member states of the European Union and NATO to incorporate some/several states of the Shatter Belt into their own zone of protection and/or federation. Nation-states of the region tend to follow the EU Agenda 2000 rules with Slovenia one of the first! 相似文献
983.
984.
Neotethyan suprasubduction zone ophiolites represent anomalous oceanic crust developed in older host basins during trench rollback cycles and later entrapped in orogenic belts as a result first of trench-passive margin and then continent–continent collisions. The Middle Jurassic Mirdita zone ophiolites in northern Albania constitute a critical transition between the dominantly mid-ocean ridge basalt (MORB)-related Early Jurassic Alpine–Apennine ophiolites in the west and supra-subduction zone (SSZ)-generated Cretaceous Eastern Mediterranean ophiolites in the east. The previously recognized Western- and Eastern-type ophiolites in the Mirdita zone display significant differences in their internal structure and pseudostratigraphy, but their geochemical affinities are more gradational in contrast to the earlier claims that these ophiolites may have formed in different tectonic settings at different times. Crosscutting relations of dike intrusions in the Eastern-type ophiolites indicate changes in the chemistry of magmatic plumbing systems from basaltic to andesitic, dacitic, rhyodacitic, and boninitic compositions through time and from west to east. The chemostratigraphy of the extrusive sequence in the Western-type ophiolites shows that the MORB-like tholeiitic rocks display a significant decrease in their TiO2 contents and Zr concentrations stratigraphically upward, although their εNd(T) values (+ 7.3 to + 6.9) show minor variation. The basaltic andesites in the upper 100 m of the Western extrusive sequence have island arc tholeiite (IAT)-like chemical characteristics (low-Ti, lower HFSE and HREE distribution, significant LREE depletion and higher Co, Ni, and Cr contents) that signify increased subduction influence in magma/melt evolution. The Eastern-type extrusive rocks range in composition from basaltic andesite to andesite, dacite and rhyodacite stratigraphically upward mimicking the temporal changes in the sheeted dikes, and they display constant Zr ( 50 ppm) but significantly varying Cr contents. The TiO2 contents of their pyroxenes are < 0.3 wt.%, and their εNd(T) values decrease from + 6.5 in the lower parts to + 3.1 in the uppermost section of the sequence. Farther east in the extrusive sequence the youngest boninitic lavas and dikes have εNd(T) values between − 1.4 and − 4.0. These chemical variations through time point to a mantle source increasingly contaminated by subduction-derived aqueous fluids and sediments, which were incorporated into the melt column beneath an extending protoarc–forearc region. Slab retreat and sinking played a major role in establishing asthenospheric upwelling and corner flow beneath the forearc mantle that in turn facilitated shallow partial melting of highly depleted harzburgitic peridotites, producing boninitic magmas. This chemical progression in the Mirdita zone ophiolite volcanism is similar to the temporal variations in magma chemistry documented from very young intraoceanic arcs built on recently generated backarc crust (i.e., South Sandwich arc). The Western and Eastern-type ophiolites in the Mirdita zone are therefore all subduction-related with the subduction zone influence in the lavas increasing stratigraphically upward as well as eastwards, suggesting a west-dipping slab geometry. The Mirdita zone and the Western Hellenic ophiolites in the Balkans were produced within a marginal basin that had evolved between the Apulian and Pelagonian microcontinents, and were subsequently emplaced onto their passive margins diachronously through different collisional processes. 相似文献
985.
稀有矿物天津蓟县锰方硼石振动光谱特征研究 总被引:2,自引:0,他引:2
锰方硼石是一种罕见的锰氯硼酸盐矿物(Mn_3B_7O_(13)Cl),天津蓟县锰方硼石矿床是世界上唯一一个锰方硼石矿床,该地锰方硼石矿物粒度细小(50~300 nm),与美国锰方硼石存在明显差别。目前涉及我国锰方硼石的研究较少,为了探究稀有矿物蓟县锰方硼石矿物学和材料学特征,本文对其进行振动光谱和高温拉曼光谱研究。常温振动光谱结果表明,蓟县锰方硼石与美国锰方硼石各主要谱带归属一致,但峰位整体上表现为向高频方向偏移且谱峰宽、强度小。高温拉曼光谱显示,随着温度升高,谱带向低频方向偏移,位移距离随温度升高呈现先增大后减小的趋势,且在680~687K处位移距离出现转折。蓟县锰方硼石粒度细小是造成上述谱峰变化的主要原因。本文运用高温拉曼技术对粒度极为细小的锰方硼石进行测试分析,研究其谱峰变化与相变的关系,实验证明高温拉曼光谱可以作为研究矿物相变的一种有效手段。 相似文献
986.
Russia has significant potential for reducing its carbon emissions. However, investment in new low-carbon technologies has significant risks. Ambiguous energy and climate policy in Russia, along with deterioration of the country's investment climate, create investment barriers that are well described in qualitative terms in the literature. This paper attempts to provide a quantitative analysis of these barriers. For this numerical experiment, we apply the RU-TIMES model. Using a real options methodology, we estimate the risk-adjusted cost of capital in the Russian energy sector (including energy production and consumption technologies represented in the TIMES framework) to be approximately 43% (including a risk-free interest rate) and demonstrate the high risk of investment into energy-efficient and low-carbon technologies. Any future low-carbon emissions pathway depends on the ability of the Russian government to reduce climate and energy policy uncertainties, and to reduce financial risks through improvements of the general investment climate.
Key policy insights
The high cost of capital investment into Russian energy production and consumption may prevent the adoption of new energy-efficient and low-carbon technologies.
These investment risks, if not addressed, will delay Russia's low-carbon transition for the coming decades.
Adopting a clear and unambiguous long-term climate and energy policy is important to reduce these risks and alleviate some of the barriers to the new technologies.
The first step could be ratification of the Paris Agreement and adoption of a long-term emission target for the period up to 2050.
987.
Tianyang Hu Lei Liu Weijian Zhou Yongjun Shao Huan Li Zhongfa Liu Liang Cao Guofeng Xu Jiaxian Li 《Chemie der Erde / Geochemistry》2022,82(2):125881
The classical mechanism “source-transport-storage” of the formation of porphyry copper deposit has been advanced in recent studies, as the “source” is not the main factor for the mineralization in some Cu deposits, and the metallogeny may be affected by other variables factors during the magma-fluid transportation or storage. We recommend the essential role of trans-magmatic fluid in the ore-forming process, this fluid is released from the melting of the sedimentary overlying the subducted plate with high water and volatiles concentrations and high oxygen fugacity. The Baoshan granodioritic cryptoexplosion breccia representing the influence of hydrothermal events as well as the unaltered Baoshan granodiorite porphyry are conducted by LA-MC-ICP-MS analysis, to identify the contribution of trans-magmatic fluid. In case of the εNd(t) of whole rock do not increase with the MgO increasing and SiO2 decreasing, the large variations of zircons εHf(t) values in Baoshan granodiorite porphyry (BGP, ?14.24 to ?6.38) and Baoshan granodioritic crypto-explosion breccia (BGCB, ?25.24 to ?6.62) were considered to be the interaction of partial melting of ancient mafic lower crust and Neoproterozoic juvenile crust. However, the copper mineralization requires high oxygen fugacity and a large amount of water, according to the tectonic settings of Baoshan, we recommend that it is the trans-magmatic fluid trapping and concentrating Cu from the whole pluton during the upwelling driven by magma convection. The initial magma was stalled by the ductile-brittle transition at shallow depths of upper-crust. The trans-magmatic fluid leads to the pressure increases at the top of the initial magma, then the overlying rock is ruptured and cryptoexplosion produced. Moreover, after the cryptoexplosion, the sudden reduction of circumference temperature and pressure leads to the decrease in the oxygen fugacity of the ore-forming system, which will change the valence state of sulfur from S6+ to S2?. Finally, sulfur precipitates with chalcophile elements like copper in the metallogenic system and forms porphyry copper deposits with the low Sr/Y ratio. This study highlights the use of trans-magmatic fluid and ductile-brittle transition in the formation of the Baoshan porphyry copper deposits. 相似文献
988.
分支河流体系的讨论有助于促进各类冲积体系的分类学研究,并可促进源—汇体系分析的定量化。博茨瓦纳的奥卡万戈(Okavango)曲流河扇是分支河流体系的典型代表,具有独特的沉积学、水文学和地貌学特征,主要特点如下:①河道形态属于单线曲流河道向下游分叉型,顺流方向产生弯度不一的分支河道网络,从顶点向下游方向,河道呈放射状,由河谷内的限制性河道变为盆地内的非限制性河道;②顺斜坡向下,河道分叉作用增强,河道的尺度和规模减小,受物源控制,无论是曲流河道还是低弯度河道,皆为砂质载荷,河道宽度、水体深度和沉积物粒度虽有系统变化但不显著,且在极低的坡度控制下,随着流量的减少,河道由曲流河逐渐变为低弯度河,河道形态转化的主要影响因素是坡度、流量、沉积物粒级和河岸强度;③根据湿地和河道分布特征,可将扇体划分为补给河谷、近源扇、中部扇和远端扇4个亚环境:补给河谷以单线曲流带和不同规模的迂回坝发育为特征,近源扇主要为泥炭限制的分支河道和河间沼泽沉积,中部扇主要为曲流河和低弯度河沉积,沼泽减少,漫滩增加,远端扇为宽浅型的非限定性河道,以沙岛林地之间的漫滩沉积为主;④沉积物主要为未固结的石英砂,主要来源于卡拉哈里盆地近代风成沉积,砂质纯净,分选和磨圆俱佳,缺乏细粒杂基,粒间细粒组分主要为生物成因的硅藻、植硅石和有机物质,亦见有方解石和二氧化硅胶结物。
对现代曲流河扇体系进行调查的重要目的就是研究地下类似沉积体系的分布。通过对我国大型含油气盆地相关“内陆三角洲”沉积特征和沉积规律的重新认识,可为油气资源的勘探开发提供预测模式。鄂尔多斯盆地山西组沉积时期,沉积作用受盆地北缘物源控制,来自北部物源的碎屑物质在宽阔的湿地平原上发育了多套分支河流沉积体系,主要为曲流河扇沉积体系。顺着沉积斜坡向下,河道的尺度和规模减小,沉积物粒度变细,煤层和暗色泥岩厚度变小,缺乏明显的三角洲前缘沉积环境及稳定的前三角洲深水相。沉积组合主要表现为分支河道砂岩、漫岸细粒沉积与湿地泥岩及薄煤层的互层,为大气田的形成奠定了沉积基础。 相似文献
989.
含水介质的空间分布及其非均质性对地下水流和溶质运移有着重要的影响。以淮南顾桥矿区作为研究对象,为了刻画矿区松散层含水介质的空间分布,使用转移概率地质统计方法建立含水介质的随机模型,对矿区水文地质结构的空间连续性和空间变异性进行表征;并将随机模拟得到的顾桥矿区含水介质剖面图与矿区原始水文地质剖面进行对比。结果表明,基于转移概率地质统计模拟方法可以比较准确地刻画矿区的水文地质结构;模拟剖面与原始水文地质剖面的比较显示模拟结果与实际含水介质空间分布情况有较好的一致性,转移概率地质统计方法在对含水介质非均质性刻画中具有较好的适用性。 相似文献
990.
《Sedimentology》2018,65(3):952-992
Hybrid event beds comprising both clean and mud‐rich sandstone are important components of many deep‐water systems and reflect the passage of turbulent sediment gravity flows with zones of clay‐damped or suppressed turbulence. ‘Behind‐outcrop’ cores from the Pennsylvanian deep‐water Ross Sandstone Formation reveal hybrid event beds with a wide range of expression in terms of relative abundance, character and inferred origin. Muddy hybrid event beds first appear in the underlying Clare Shale Formation where they are interpreted as the distal run‐out of the wakes to flows which deposited most of their sand up‐dip before transforming to fluid mud. These are overlain by unusually thick (up to 4·4 m), coarse sandy hybrid event beds (89% of the lowermost Ross Formation by thickness) that record deposition from outsized flows in which transformations were driven by both substrate entrainment in the body of the flow and clay fractionation in the wake. A switch to dominantly fine‐grained sand was accompanied initially by the arrest of turbulence‐damped, mud‐rich flows with evidence for transitional flow conditions and thick fluid mud caps. The mid and upper Ross Formation contain metre‐scale bed sets of hybrid event beds (21 to 14%, respectively) in (i) upward‐sandying bed set associations immediately beneath amalgamated sheet or channel elements; (ii) stacked thick‐bedded and thin‐bedded hybrid event bed‐dominated bed sets; (iii) associations of hybrid event bed‐dominated bed sets alternating with conventional turbidites; and (iv) rare outsized hybrid event beds. Hybrid event bed dominance in the lower Ross Formation may reflect significant initial disequilibrium, a bias towards large‐volume flows in distal sectors of the basin, extensive mud‐draped slopes and greater drop heights promoting erosion. Higher in the formation, hybrid event beds record local perturbations related to channel switching, lobe relocations and extension of channels across the fan surface. The Ross Sandstone Formation confirms that hybrid event beds can form in a variety of ways, even in the same system, and that different flow transformation mechanisms may operate even during the passage of a single flow. 相似文献