The impact of river dredging on ostracod assemblages in the Krąpiel River (NW Poland)

2014 ◽  
Vol 185 (3) ◽  
pp. 295-305 ◽  
Author(s):  
Agnieszka Szlauer-Łukaszewska ◽  
Andrzej Zawal
Keyword(s):  
The Impact ◽  
Nw Poland

scholarly journals The impact of dredging of a small lowland river on water beetle fauna (Coleoptera)

2016 ◽  
Author(s):  
Piotr Dabkowski ◽  
Paweł Buczynski ◽  
Andrzej Zawal ◽  
Edyta Stepien ◽  
Edyta Buczynska ◽  
...  
Keyword(s):  
Species Number ◽  
Lowland River ◽  
Fish Ponds ◽  
Sediment Composition ◽  
Small Water ◽  
Water Beetle ◽  
Dominance Structure ◽  
Aquatic Beetle ◽  
The Impact ◽  
Nw Poland

<p>Using the example of a regulated stretch of the Krąpiel River (NW Poland), an analysis of the impact of dredging on the aquatic beetle (Coleoptera) fauna was made. After dredging the beetle fauna became markedly poorer quantitatively and had lower species diversity. Moreover, the qualitative composition and dominance structure were highly transformed. However, species number and diversity increased rapidly and were restored within just half a year. The structure of the restored fauna was most strongly influenced by vegetation, flow velocity and bottom sediment composition. The first to colonize the river were eurytopic beetles and species typical of small water bodies, which had significant refuges in the form of fish ponds bordering on the river; these species dominated the assemblage throughout the study period. Rheophiles with less dispersal power appeared later, and finally rheobionts, in low numbers but occupying an increasing number of sampling sites. </p>

The structure of precipitation and rainfall erosivity in the upper Parsęta catchment (Drawskie Lakeland, NW Poland) in 1987-2020 as an indicator of climate change

2021 ◽  
Author(s):  
Mikolaj Majewski ◽  
Józef Szpikowski ◽  
Monika Domańska ◽  
Grażyna Szpikowska
Keyword(s):  
Climate Change ◽  
Snow Cover ◽  
Vegetation Period ◽  
Base Station ◽  
Annual Rainfall ◽  
Rainfall Erosivity ◽  
Water Shortages ◽  
Integrated Monitoring ◽  
The Impact ◽  
Nw Poland

&lt;p&gt;The impact of climate change observed in recent decades can be noticed in the structure of precipitation. The increasing amount of periods without rainfall, decreasing annual snowfall totals, and shortening the duration of snow cover significantly affect water resources and the intensity of a number of environmental processes, such as soil erosion by water.&lt;/p&gt;&lt;p&gt;The main aim of this paper is to determine the structure of rainfall in years 1987-2020, based on series of meteorological measurements in the Pars&amp;#281;ta Base Station of Integrated Monitoring of Natural Environment at Storkowo in Drawskie Lakeland (NW Poland). The analyzes included precipitation amounts, number of days with precipitation, rainfall intensity, kinetic energy and erosivity and several rainfall indices. During this period, there is observed a significant increase of air temperature, which equals 0.47&amp;#176;C for 10 years. In the case of precipitation, a small increasing trend is marked statistically insignificant. The average annual precipitation was 698.6 mm, whilst precipitation in the winter half-year equalled 41.2% of total and 58.8% in the summer half-year. The annual rainfall erosivity, calculated according to Wishmeier and Smith&amp;#8217;s formula, changed from 144.7 to 782.1 MJmm/ha/h, while Modified Fournier Index (MFI) ranged from 53.8 mm to 119.0 mm and was not statistically significant.&lt;/p&gt;&lt;p&gt;The analysis of precipitation with different daily totals did not show a significant increase in the share of precipitation with higher values. The relative precipitation index (RPI) showed no increase in the number of dry months of a year. Moreover, the analysis of occurrence of periods of light droughts, dry spells and droughts does not indicate any significant increase in the number and frequency of such events. On the other hand, a similar analysis of vegetation period (April-September) shows statistically insignificant trend of decrease in the number and frequency of precipitation less series. Another indicator important for the assessment of water conditions, the Sielianinov hydrothermal coefficient was calculated for period April-October, and showed lack of long-term trend changes in the observed period.&lt;/p&gt;&lt;p&gt;The water shortages in the upper Pars&amp;#281;ta catchment observed in recent years are probably the result of decrease in the contribution of snow in the precipitation structure and a significant reduction in the number of days with snow cover. This limits the underground retention and surface outflow and has an impact on the functioning of biotic environment and agriculture.&lt;/p&gt;

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Organic Syntheses During the Impact of a Comet with a Gaseous Planet

1997 ◽  
Vol 161 ◽  
pp. 189-195
Author(s):  
Cesare Guaita ◽  
Roberto Crippa ◽  
Federico Manzini
Keyword(s):  
Polymeric Material ◽  
Molecular Form ◽  
Parent Compound ◽  
Blue Filter ◽  
Organic Syntheses ◽  
The Impact

AbstractA large amount of CO has been detected above many SL9/Jupiter impacts. This gas was never detected before the collision. So, in our opinion, CO was released from a parent compound during the collision. We identify this compound as POM (polyoxymethylene), a formaldehyde (HCHO) polymer that, when suddenly heated, reformes monomeric HCHO. At temperatures higher than 1200°K HCHO cannot exist in molecular form and the most probable result of its decomposition is the formation of CO. At lower temperatures, HCHO can react with NH3 and/or HCN to form high UV-absorbing polymeric material. In our opinion, this kind of material has also to be taken in to account to explain the complex evolution of some SL9 impacts that we observed in CCD images taken with a blue filter.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

Unusual Microstructure in Shock-Compacted Graphite

1970 ◽  
Vol 28 ◽  
pp. 474-475
Author(s):  
Lucien F. Trueb
Keyword(s):  
Mechanical Characteristic ◽  
Compression Wave ◽  
Gray Zone ◽  
Flyer Plate ◽  
Compacted Graphite ◽  
The Impact

Crushed and statically compressed Madagascar graphite that was explosively shocked at 425 kb by means of a planar flyer-plate is characterized by a black zone extending for 2 to 3 nun below the impact plane of the driver. Beyond this point, the material assumes the normal gray color of graphite. The thickness of the black zone is identical with the distance taken by the relaxation wave to overtake the compression wave.The main mechanical characteristic of the black material is its great hardness; steel scalpels and razor blades are readily blunted during attempts to cut it. An average microhardness value of 95-3 DPHN was obtained with a 10 kg load. This figure is a minimum because the indentations were usually cracked; 14.8 DPHN was measured in the gray zone.

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