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81.
Gullies are among the most intriguing structures identified on the surface of Mars. Most common are gullies located on the slopes of craters which are probably formed by liquid water transported by shallow aquifers (Heldmann, J.L., Carlsson, E., Johansson, H., Mellon, M.T., Toon, O.B. [2007]. Icarus 188, 324-344). Two particular types of gullies are found on slopes of isolated hills and dunes. The hill-slope gullies are located mostly at 50°S, which is at the high end of latitudes of bulk of the gullies found so far. The dune gullies are found in several locations up to 65°S (Reiss, D., Jaumann, R., Kereszturi, A., Sik, A., Neukum, G. [2007]. Lunar Planet. Sci. XXXVIII. Abstract 1993), but the best known are those in Russel crater at 54°S. The hill and dune gullies are longer than others making the aquifers explanation for their formation unlikely (Balme, M., Mangold, N., Baratoux, D., Costard, F., Gosselin, M., Masson, P., Pnet, P., Neukum, G. [2006]. J. Geophys. Res. 111. doi:10.1029/2005JE002607). Recently it has been noted that thin liquid films of interfacial water can play a role in rheological processes on the surface of Mars (Moehlmann, D. [2008]. Icarus 195, 131-139. Kereszturi, A., Moehlmann, D., Berczi, Sz., Ganti, T., Kuti, A., Sik, A., Horvath, A. [2009]. Icarus 201, 492-503.). Here we try to answer the question whether interfacial liquid water may occur on Mars in quantities large enough to play a role in formation of gullies. To verify this hypothesis we have calculated thermal models for hills and dunes of various steepness, orientation and physical properties. We find that within a range of average expected values of parameters it is not possible to have more than a few monolayers of liquid water at depths greater than a centimeter. To create subsurface interfacial water film significantly thicker and hence to produce conditions for the slope instability, parameters have to be chosen to have their extreme realistic values or an additional source of surface heating is needed. One possibility for additional heating is a change of atmospheric conditions due to a local dust storm. We conclude that if interfacial water is responsible for the formation of the hill-slope gullies, our results may explain why the hill gullies are rare. 相似文献
82.
Wojciech Tylmann Kamila Szpakowska Christian Ohlendorf Micha? Woszczyk Bernd Zolitschka 《Journal of Paleolimnology》2012,47(1):55-70
A three-year field study was conducted in Lake Suminko, Poland, to gain an understanding of the limnological variables that
influence the formation and spatial extent of annually laminated sediments in the lake. The water body is divided into three
depth strata, the mixolimnion, chemocline and monimolimnion, each defined by distinct values of temperature, electrical conductivity
and oxygen concentration. Typical for meromictic lakes, the monimolimnion remains perennially anoxic and is rich in dissolved
solids and nutrients. The annual pattern of particle flux in Lake Suminko is closely related to biochemical processes in the
euphotic zone. During winter months we observed very low accumulation rates of non-carbonaceous matter, while during the rest
of the year, three periods of calcite deposition were recorded (April, July–August, and October–November). The periods of
high calcite deposition corresponded with algal blooms and oxygen concentration maxima. Two principal factors contribute to
meromixis in Lake Suminko: (1) the basin is sheltered, preventing wind mixing, and (2) biochemical processes in the lake associated
with high lacustrine productivity. Meromictic conditions must control the formation and preservation of laminated sediments
in the lake because preserved laminations occur only in areas where the lake floor lies below monimolimnetic waters. 相似文献
83.
84.
Wojciech Stopinski 《地震学报(英文版)》1992,5(4):831-840
The paper presents the results of measurements of electric resistivity changes in the sample subject to uniaxial loading in
the automatic press. Four-electrode method was used. All minielectrodes were fixed inside the samples. The zone of future
fracture was determined by a kind of pre-cut. Distribution of minielectrode sets in various parts of the samples ensured the
possibility of monitoring the changes of electric resistivity either in the direct fracture zone, or outside of that zone.
The comparison of the measurement data obtained in the fracture zone and outside of it shows that electric resistivity method
can be used to failure prediction in both zones, although the precursor phenomena are much better visible in the direct fracture
zone. The typical progress of changes obtained in the fracture zone is similar to that observed while investigating the resistivity
changes in mines. Decreased repetition time of measurements improved the quality of results. New precursor phenomena were
found out in the course of electric resistivity changes.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 220–228, 1992. 相似文献
85.
Thirteen polycyclic aromatic hydrocarbons (PAH) compounds have been identified in spa waters of 10 different health sources in the Sudetes region. In some of the waters the amount of PAH exceed the standard limits set up by the World Health Organization (WHO). The results obtained show that PAH can be a sensitive indicator of pollution of underground water. 相似文献
86.
Heavy metals in sediments as evidence for recent pollution and quasi-estuarine processes: an example from Lake Druzno,Poland 总被引:1,自引:0,他引:1
Wojciech Tylmann Roman Gołębiewski Piotr Paweł Woźniak Karolina Czarnecka 《Environmental Geology》2007,53(1):35-46
This article presents the results of a geochemical investigation of sediments from Lake Druzno (northern Poland), a reservoir
fed by freshwater from the catchment, with periodic input of brackish water from Vistula Lagoon. This study analyzed the spatial
variation in heavy metal content in surface sediments as well as the temporal changes in metal content in two sediment cores
dated using the 210Pb method. In the surface sediments, the highest metal concentrations were recorded in the northern part of the lake, with
lower concentrations in the central and southern parts. Absolute values of metal concentrations in the cores were low, but
normalization with respect to Al showed an increase during the second half of the 20th century. Mean enrichment factors (EF)
in sediments from the second half of the 20th century ranged from insignificant (1–1.2) for Fe to (1.55–3.3) for Cu, Cd, Pb
and Zn. The sediments deposited before 1950 had lower EF values (>1.5) and had low variability. Results from both the surface
sediments and the cores indicate that the main source of lake pollution is brackish water intrusion from the Vistula Lagoon
via the contaminated River Elbląg. 相似文献
87.
Gully erosion is one of the greatest natural hazards in the loess areas of E. (Eastern) Poland. At the same time, permanent gullies are a major tourist attraction and can provide a basis for the development of geotourism. The study objective was to assess the possibilities of using the loess gullies for educational purposes. Detailed studies were conducted within the municipality of Kazimierz Dolny, an area with an extremely high concentration of permanent gullies. The questionnaire survey of students and tourists (nearly 300 surveys were completed) showed that the respondents’ knowledge of geomorphology was limited, despite their familiarity with gullies. In most cases, they were unable to accurately identify the determinants of gully erosion, its negative effects and methods for preventing it. An assessment of the tourism and geotourism potential of the municipality made it possible to identify the sites (gullies) that can perform an educational function, with regard to gully erosion. The establishment of the Ma?opolska Vistula Gap Geopark, whose highlights will include numerous loess gullies, can pave the way for the development of geotourism. 相似文献
88.
Earthquake of November 30, 2004, in Podhale region, southern Poland, was of unexpectedly big size in this area of weak seismicity.
As Poland is considered a country of low seismicity, the earthquake has caused concern about seismic hazard in Poland, especially
since it took place shortly after the even more unexpected Kaliningrad Region, Russia, earthquakes of September 21, 2004,
that inflicted minor damage in northern Poland. The paper presents the findings on the Podhale earthquake which reached macroseismic
intensity up to 7 and magnitude 4.7 (m
b
; ISC). The event was felt up to a distance of about 100 km and inflicted slight damage to buildings in its narrow epicentral
area, thus evidencing its relatively shallow depth. The quake has been located near the village of Skrzypne, about 15 km west-southwest
of the district capital Nowy Targ. The source mechanism has been found to be of dip slip normal fault type, although a problem
remains of association of this mechanism with known tectonic dislocations in the region. The earthquake has been followed
by a long series of aftershocks. Their distribution in time is also studied and the biggest aftershocks have been located. 相似文献
89.
Konrad J. Kossacki Wojciech J. Markiewicz Yuri Skorov Norbert. I. Kmle 《Planetary and Space Science》1999,47(12):1521-1530
In papers dealing with evolution of cometary nuclei it is commonly assumed that the coefficients of sublimation s and condensation c of vapour are both equal to one. The experimental investigation of ice samples under simulated cometary-like conditions (Kossacki, K.J., Kömle, N.I., Leliwa-Kopysty
ski, J., Kargl, G., 1997. Thermal and structural evolution of cometary subsurface layer: selfconsistent model and experimental verification. Icarus 128, 127–144) suggests, however, that the sublimation flux calculated with the Hertz–Knudsen formula and the above assumption is nearly an order of magnitude too high. This may imply that actual values of s for the ice/dust sample used in these experiments are of the order of 0.1. A similar conclusion can be drawn for c from the results of various experiments concerning growth of ice crystals from the vapour phase and their sublimation (Lamb, D., Scott, W.D., 1972. Linear growth rates of ice crystals grown from the vapor phase. Journal of Crystal Growth 12, 21–31; Beckmann, W., Lacmann, R., 1982. Interface kinetics of growth and evaporation of ice II. Journal of Crystal Growth 58, 433–442; Sei, T., Gonda, T., 1989. The growth mechanism and the habit change of ice crystals growing from the vapour phase. Journal of Crystal Growth 94, 697–707). The exact values of both of these coefficients depend on various parameters such as temperature, concentration of surface impurities and deviation of the vapour pressure from that of the phase equilibrium. In this work the temperature dependence of the sublimation and condensation coefficients is discussed and an appropriate formula is proposed to fit the experimental results. This new formulation is then used to analyse the implications for the thermal conductivity of a porous cometary-like ice and the rate of vapour flux from a cometary nucleus. 相似文献
90.
Beata Mazur Janusz Kaluzny Wojciech Krzemiski 《Monthly notices of the Royal Astronomical Society》1999,306(3):727-735
We report the results of a CCD search for short-period variables in the field of a southern globular cluster NGC 6362. We identified 19 new candidate variables, five of which are cluster RR Lyraes, four are probable SX Phe-type stars and eight are eclipsing binaries. Of the discovered binaries, three are EA-type systems, two of which are located on the cluster CMD in the turn-off region and the third 1 mag above the turn-off point, in the yellow straggler region. Five other systems are of W UMa type, three of which are foreground objects and two are likely cluster members. The remaining two candidates exhibit a modulation of the brightness level with an amplitude of 0.1–0.2 mag; further observations are needed to reveal the nature of their variability. Phased VI light curves for 20 variables (18 RR Lyrae stars and two blue stragglers) located in the central region of the cluster are presented. 相似文献