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141.
This publication is a contribution to discussion on the geometry and petrography of the rock complex responsible for the Carpathian
conductivity anomaly. We analysed arguments showing that this anomaly is caused by induction in the sedimentary basin, and
make a critical review of various data to find out whether the good conductivity is connected with a rock complex containing
graphite or mineralized water. We conclude that a more likely mechanism is the ionic one, i.e., the existence of fluids, although
a final decision can only be made on the basis of deep drillings. 相似文献
142.
143.
The paper summarises the history of human settlement in the Sudetes from the Bronze Age. A more intensive stage was reached
in the Middle Ages when settlers from the west established new villages deep in the mountain valleys. By the beginning of
the 20th century the Sudetes were already overpopulated but after a near-complete ethnic replacement from a German to a Polish
population in 1945–8, population continued to grow until the 1980s. However, the economic system was hardly sustainable by
this time. There were many polluting industries in the region and massive transboundary pollution from adjacent areas of Czechoslovakia
and Germany had a devastating effect on the forests. Moreover, subsidised state agriculture placed heavy pressure on vulnerable
mountain grazings. Since 1989 there has been a process of deindustrialisation in the Sudetes and surrounding areas and, with
the disappearance of the state farms and the reduction in subsidies, agriculture is now better adjusted to the natural potential
and is complemented by a promising start with agrotourism. The population of the region is growing relatively slowly (0.8%
per annum 1956–1999), with the rural areas now in decline. A sustainable future for the region is now a possibility, but while
there is a consensus for continued environmental reconstruction, supported by alternative economies, this will have to be
carefully managed in the years ahead when EU accession may bring heavier development pressures than those evident at the moment.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
144.
Some ilmenite concentrates obtained from oleate flotation of ilmenite ores from NE Poland contain less than the required 45% TiO2 due to the presence of green spinels (hercynite and pleonaste). Such concentrates were further upgraded by different separation techniques. It was established at microlaboratory scale that magnetic, gravity and high-tension separations can provide qualified ilmenite concentrates with TiO2 recovery in the order of 50 to 80%. 相似文献
145.
气候变暖背景下扎龙湿地气候变化特征 总被引:3,自引:1,他引:3
基于扎龙湿地1955—2004年逐日气温和降水量资料,采用滑动平均、趋势分析、小波分析和Mann-Kendall及Yamamoto检验等方法,探讨了扎龙湿地近50年的气候变化特征。结果表明:①研究时段内扎龙湿地年及四季平均气温均呈上升趋势,年平均气温在1988年发生了一次明显的突变,其后气温达到一个更显著的增暖时期,20世纪90年代以来的增温非常显著,是50年以来的最高温期;②扎龙湿地年及各季降水量除春季外均呈减少趋势,秋季降水减少趋势最显著,研究时段内没有明显的突变过程;③20世纪80年代中期之后扎龙湿地暖冬和热夏事件的发生频率和强度显著增加,大气湿润度在减小,气候在向暖干方向发展。 相似文献
146.
Małgorzata Białek 《Acta Geophysica》2006,54(1):60-70
Long-term changes in total ozone time series for Arosa, Belsk, Boulder and Sapporo stations are examined. For each station
we analyze time series of the following statistical characteristics of the distribution of daily ozone data: seasonal mean,
standard deviation, maximum and minimum of total daily ozone values for all seasons. The iterative statistical model is proposed
to estimate trends and long-term changes in the statistical distribution of the daily total ozone data. The trends are calculated
for the period 1980–2003. We observe lessening of negative trends in the seasonal means as compared to those calculated by
WMO for 1980–2000. We discuss a possibility of a change of the distribution shape of ozone daily data using the Kolmogorov-Smirnov
test and comparing trend values in the seasonal mean, standard deviation, maximum and minimum time series for the selected
stations and seasons. The distribution shift toward lower values without a change in the distribution shape is suggested with
the following exceptions: the spreading of the distribution toward lower values for Belsk during winter and no decisive result
for Sapporo and Boulder in summer. 相似文献
147.
Piotr Owczarek Adam Nawrot Krzysztof Migała Ireneusz Malik Bartosz Korabiewski 《Boreas: An International Journal of Quaternary Research》2014,43(2):384-402
Changes in the supply of water and sediment to high‐latitude rivers related to contemporary climate change and glacier fluctuations largely determine the activity of fluvial processes. This study reconstructs fluvial dynamics since the end of the Little Ice Age (LIA) in two small, partially glaciated basins in the southern part of Spitsbergen, Svalbard Archipelago. We use a combination of aerial photograph interpretation, field mapping and dendrochronological analysis. Sequences of abandoned channels and glacifluvial terraces are distinctly visible in middle and lower parts of the Brattegg and Arie basins in this area. The advance of glaciers during the LIA in the upper part of the basins led to the development of a braiding pattern and to channel aggradation corresponding to the highest glacifluvial levels. The decreasing activity of these braidplains occurred at the turn of the 19th and 20th centuries, immediately prior to a significant incision period. A second generation of braided channels developed during the first half of the 20th century. Ice‐marginal lake development, less input of fine‐grained sediment to the river channel, and fast incision began from the second half of the 20th century onward. During the last two decades, the main fluvial response to the climatic warming has been contraction of flow within a narrower channel and the abandonment of braidplains. The increased lateral erosion and rate of downcutting and the formation of the most downstream reaches of the modern valley bottom occurred in the 1980s and 1990s. This process was intensified under flood conditions generated by extreme rainfall events. These micro‐scale (small partially glaciated basins) observations concerning the changes of the activity of fluvial processes since the end of LIA may be helpful for the reconstruction of past fluvial changes over longer time scales. 相似文献
148.
Paul M. Myrow Jahandar Ramezani Anne E. Hanson Samuel A. Bowring Grzegorz Racki Michał Rakociński 《地学学报》2014,26(3):222-229
Precise U–Pb zircon dates from three volcanic ash beds that bracket the Hangenberg Shale in the Holy Cross Mountains, Poland, constrain the age and duration of one of the most significant palaeobiological events of the Palaeozoic Era, the Hangenberg Event. It is linked to a terminal Devonian global shift from greenhouse to icehouse climate conditions, a global transgression, and widespread black shale deposition. Our results constrain the Hangenberg Event to between 358.97 ± 0.11 Ma and 358.89 ± 0.20 Ma, with a calculated duration of 0.05 +0.14/?0.05 Ma. A third, underlying ash bed yielded a distinctly older age of 359.97 ± 0.46 Ma. The duration of ~50–100 ka. for the event is comparable to those of Quaternary glaciations, and is consistent with both a glacio‐eustatic origin for the eustatic fluctuations and changes in ocean chemistry that led to this major reorganization of the biosphere. 相似文献
149.
This study investigates the statistical correlation between the power input into the magnetosphere due to reconnection and the subsequent dissipation of this energy in the magnetosphere as measured by the UT parameter (Perreault and Akasofu, 1978). It is found that of the three expressions for this energy input PW, PK (Gonzalez and Gonzalez, 1984) and ε (Perreault and Akasofu, 1975; Kan et al.,1980), PW yields the highest correlation with the energy consumption of the magnetosphere. 相似文献
150.
Visual observations of 1995 Perseid meteor stream made by Polish astronomy amateurs are reported. Using this material we obtained new accurate points in the activity profile during maximum. The Zenithal Hourly Rates (ZHRs) for the whole period of activity are presented. We also discuss the magnitude, the colour and the velocity distributions of Perseids. 相似文献