Wyniki wyszukiwania - Biblioteka Nauki

1

Microstructure evolution and mechanical properties of underwater dry welded metal of high strength steel Q690E under different water depths

100%

Sun K. , Huc Y. , Shi Y. , Liao B.

Polish Maritime Research

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2020

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tom nr 4

112--119

EN

Q690E high strength low alloy (HSLA) steel has been intensively applied in maritime engineering. Also, the underwater dry welding (UDW) technique has been widely used to repair important offshore facilities. In this paper, joints of Q690E steel were fabricated through single-pass underwater dry welding at three pressures (0, 0.2, and 0.4 MPa). To study the effect of the pressure on the microstructure and mechanical properties of the UDW joint, an optical microscope (OM) and scanning electron microscope (SEM) were used to observe the microstructure and fracture morphology of the welded joints. The electron backscattered diffraction (EBSD) technique was used to analyse the crystallographic features and the crystallographic grain size of the ferrites. The proportion of acicular ferrite (AF) in the UDW joints and the density of low-angle boundaries increase dramatically with the increasing depth of water. The weld metal of UDW-40 shows higher strength because more fine ferrites and low-angle boundaries within UDW-40 impede the dislocation movement.

2

Working of deep-water minerals with sectored way

100%

Sukach M.

Teka Komisji Motoryzacji i Energetyki Rolnictwa

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2014

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tom 14

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nr 4

3

Physicochemical properties of water retained in midfield bog pools

86%

Urban D. , Grzywna A.

Teka Komisji Ochrony i Kształtowania Środowiska Przyrodniczego

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2013

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tom 10

4

Mapping depths of groundwater level architecture: implications on modest groundwater level declines and failures of boreholes in sedimentary environs

86%

George N. J. , Ekanem A. M. , Thomas J. E. , Ekong S. A.

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tom Vol. 69, no. 5

1919--1932

EN

Due to financial wherewithal, only shallow wells, which are extremely prone to seasonal groundwater decline, are constructed in the study area. Generally, new groundwater wells are designed to follow the criteria of the old wells, which may be vulnerable to substantial groundwater depletion through water-level decline. Going by this, newer groundwater wells constructed near older ones are 100% susceptible to the uninvestigated depletion associated with the older ones. The method used integrates vertical electrical sounding (VES) technique employing the Schlumberger electrode configuration, which measured the resistivity of geologic layers, depths and thickness with hydrogeological information, which constrained the VES interpretation. The aim was to check the spread of groundwater depth–water table ratios for the shallow aquifers. The 1-D resistivity analysis shows that the topsoil/motley topsoil has resistivity ranging from 71.8 to 1964.1 Ωm and mean 586.9 Ωm, while its depth ranges between 0.5 and 11.3 m with mean value of 2.8 m. In layer 2, while the resistivity spans between 71.3 and 1488.6 Ωm with mean value 444.6 Ωm, the depth and thickness, respectively, have a range and mean value of 2.0–170.4 m and 41.9 m and 3.4–112.2 m and 41.0 m. The third layer resistivity ranges from 7.5 to 2332.5 Ωm with mean value of 797.2 m. The depth of burial and the thickness of the third layer, respectively, have mean of 63.0 m and 74.6 m and range of 40.3–106.3 m and 50.1–115.6 m. The fourth layer penetrated by current at 150 m half of current electrode separation has undefined thickness and depth with respective resistivity range and mean of 25.3–2385.3 Ωm and 508.4 Ωm. Based on the resistivity results and nearby borehole data, sizeable numbers of borehole in the area have depths (between 40 and 80 m) that are remarkably greater than the water table depths (1.4–37.6 m). A few boreholes have depths that are sparingly greater than water levels and by the present climate change; they are not likely to be depleted by virtue of water-level declines as the well depth–water table depth ratios are still sustainable to ward of the depletion associated with water-level decline. The results indicate the spatial spread of shallow hydrogeological units as well as the water-level architecture, which is believed to provide useful information that will complement lithological logs while planning for newer groundwater well development in the area.

5

Potholes of Mountain River as Biodiversity Spots : Structure and Dynamics of the Benthic Invertebrate Community

72%

Ren H. , Yuan X. , Yue J. , Wang X. , Liu H.

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2016

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tom Vol. 64, nr 1

70--83

EN

Temporary freshwater rock pools, as special, small-sized and isolated habitats, provide ideal systems for studying island biogeography and ecological theories and processes. In this study, a total of 70 potholes of mountain rivers were sampled during the four seasons from November 2013 to October 2014 to assess the structure of the benthic invertebrate community and to identify the relationships between habitat characteristics and the community composition. Pothole area ranged from approximately 0.01 to 0.39 m2, and pothole depth ranged from 0.03 to 0.74 m. Forty-three taxa belonging to 37 families and 16 orders were collected from the potholes. The highest numbers of benthic invertebrate taxa were observed in summer and the highest average number of taxa per pothole (8.5) was observed in autumn. The diversity was the highest in spring, and the average densities of benthic invertebrates were highest in autumn. Large potholes supported more taxa than small ones and significant relationships between richness and pothole area, richness and water volume were observed. The results of Redundancy Analysis show that the community composition of benthic invertebrates in the potholes was closely correlated with water temperature, pothole area and water depth. Our results indicate that benthic invertebrate communities in river potholes are mainly structured by water depth, pothole area and water volume. The seasonal changes are also an important factor determining the presence/absence of certain taxa.

6

Assessment of metallic contamination in sediment and mullet fish (Mugil cephalus Linnaeus, 1758) tissues from the East Algerian coast

72%

Ouali N. , Belabed B. E. , Zeghdoudi F. , Rachedi M.

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tom no. 38

115--126

EN

The present work was designed to assess the contamination level in the coastal of Annaba, following the spectrophotometric determination of the level of some metallic elements (Fe, Cu, Pb, Zn, Ni and Cd) in the sediments along an increasing bathymetric gradient (10 m and 20 m), as well as in the biological indicator grey mullet (Mugil cephalus) muscle. During the winter period (2014), 12 surface sediment samples, and a total of 24 fish were collected. Once the samples are dried, crushed and sieved, 0.5 g dry weight of each sample was added to concentrated acids. The results showed that the levels of some metals are superior to the recommended guideline values, and consequently the sediment of this bay is contaminated by iron, lead and copper. The contamination index (CI) showed a general tendency in the concentration of the studied metals as follows: Fe > Pb > Cu > Zn > Ni > Cd, since the most studied metals occurred at higher concentration in depth (20 m). However, the average concentrations of metals in fishes were found to be as the following order: Fe > Zn > Pb > Cu > Ni > Cd. The consumption of fish from some contaminated sites can be dangerous because concentrations of lead, cadmium and zinc exceed the international standards. Moreover, the strong positive correlation observed between the metallic elements of sediments and fishes confirm that these metals resulted from the similar sources of the anthropic activities, such as domestic, port, industrial and agricultural waste discharges. This is confirmed by the determined of pollution load index (PLI) parameter. Conclusively, a regular monitoring program of heavy metal is recommended for protecting these organisms, and to reduce the environmental risks.

PL

W pracy oceniono poziom zanieczyszczenia strefy przybrzeżnej w okolicach Annaby na podstawie spektrofotometrycznych analiz metali (Fe, Cu, Pb, Zn, Ni and Cd) w osadach na różnej głębokości (10 i 20 m) i w mięśniach cefala pospolitego (Mugil cephalus) jako organizmu wskaźnikowego. W okresie zimowym (2014 r.) zebrano 12 próbek osadów powierzchniowych i łącznie 24 ryby. Po wysuszeniu, pokruszeniu i przesianiu próbek do stężonych kwasów dodano 0,5 g suchej masy każdej próbki. Wyniki dowodzą, że stężenie niektórych metali przekracza dopuszczalne normy, a osady w zatoce są zanieczyszczone żelazem, ołowiem i miedzią. Wskaźnik zanieczyszczenia (CI) kształtował się następująco: Fe > Pb > Cu > Zn > Ni > Cd, przy czym większe stężenie większości metali notowano na głębokości 20 m. Średnie stężenie metali w mięśniach ryb układało się natomiast w porządku: Fe > Zn > Pb > Cu > Ni > Cd. Konsumpcja ryb z niektórych skażonych stanowisk może być niebezpieczna, ponieważ stężenie ołowiu, kadmu i cynku przekracza międzynarodowe standardy. Ponadto, silna dodatnia korelacja między stężeniem metali w osadach i w rybach dowodzi, że metale te pochodzą z tych samych antropogenicznych źródeł takich jak zrzuty ścieków bytowych, portowych, przemysłowych i rolniczych. Potwierdza to oznaczony wskaźnik ładunku zanieczyszczeń (PLI). W podsumowaniu zaleca się wdrożenie regularnego programu monitoringu w celu ochrony organizmów wodnych i ograniczenia ryzyka środowiskowego.

7

Zmiany stężenia tlenu i temperatury w warunkach różnych głębokości wody w śródpolnym oczku wodnym

72%

Wesołowski P. , Brysiewicz A. , Gałczyńska M.

Woda-Środowisko-Obszary Wiejskie

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2014

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tom T. 14, z. 4

135--144

PL

Badania przeprowadzono w latach 2010–2013 w śródpolnym oczku wodnym Stare Czarnowo, w województwie zachodniopomorskim. Celem podjętych badań było określenie stężenia tlenu rozpuszczonego w wodzie i jej temperatury w warunkach zróżnicowanej głębokości wody. Pomiary wykonywano w trzech pionach badawczych o zróżnicowanej głębokości wody. W okresie badań stwierdzono, że stężenie tlenu rozpuszczonego w wodzie oczka wodnego zależało od jej głębokości w badanych pionach pomiarowych. Największe średnie z lat 2010–2013 wartości tlenu rozpuszczonego w wodzie w okresach wegetacyjnych (IV–X) zanotowano w trzecim pionie pomiarowym (III) w warunkach największej głębokości wody (3,00 g O2•m-3). Mniejsze wartości średniego stężenia tlenu stwierdzono w warunkach mniejszych głębokości wody: w pierwszym pionie badawczym (I) – 1,96 g O2•m-3, a w drugim (II) – 2,22 g O2•m-3.

EN

Studies were carried out in the years 2010–2013 in a mid-field pond Stare Czarnowo in Zachodniopomorskie Province. The aim of the study was to determine dissolved oxygen concentration and temperature at different water depths. Measurements were performed in three water profiles of different depth. The concentration of dissolved oxygen in water was found to depend on water depth. The highest mean (April to October 2010–2013) concentration (3.00 g O2 m-3) was noted in the third, deepest water profile. Lower mean concentrations of oxygen were recorded in the first (1.96 g O2 m-3) and second (2.22 g O2 m-3) water profile.

8

Potholes of mountain river as biodiversity spots: structure and dynamics of the benthic invertebrate community

72%

Ren H. , Yuan X. , Yue J. , Wang X. , Liu H.

Polish Journal of Ecology

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2016

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tom 64

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nr 1

EN

Temporary freshwater rock pools, as special, small-sized and isolated habitats, provide ideal systems for studying island biogeography and ecological theories and processes. In this study, a total of 70 potholes of mountain rivers were sampled during the four seasons from November 2013 to October 2014 to assess the structure of the benthic invertebrate community and to identify the relationships between habitat characteristics and the community composition. Pothole area ranged from approximately 0.01 to 0.39 m², and pothole depth ranged from 0.03 to 0.74 m. Forty-three taxa belonging to 37 families and 16 orders were collected from the potholes. The highest numbers of benthic invertebrate taxa were observed in summer and the highest average number of taxa per pothole (8.5) was observed in autumn. The diversity was the highest in spring, and the average densities of benthic invertebrates were highest in autumn. Large potholes supported more taxa than small ones and significant relationships between richness and pothole area, richness and water volume were observed. The results of Redundancy Analysis show that the community composition of benthic invertebrates in the potholes was closely correlated with water temperature, pothole area and water depth. Our results indicate that benthic invertebrate communities in river potholes are mainly structured by water depth, pothole area and water volume. The seasonal changes are also an important factor determining the presence/absence of certain taxa.

9

A long-term trend and temporal fluctuations of the sea level at the Polish Baltic coast

72%

Wisniewski B. , Wolski T. , Musielak S.

Oceanological and Hydrobiological Studies

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2011

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tom 40

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nr 2

10

Response of riverine benthofauna associated with gravel-pebble bottom to impoundment - interhabitat comparison

72%

Tszydel M. , Grzybkowska M. , Kurzawski M. , Kalisiak N.

Oceanological and Hydrobiological Studies

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2007

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tom 36

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nr Suppl.4

11

Predation on artificial nests imitating the broods of two rallid species: the influence of habitat features

58%

Chibowski P. , Brzezinski M. , Jedlikowski J.

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nr 4

EN

We tested the influence of nest concealment (vegetation type, density and height), water depth and nest distance from the bank on predation rates upon simulated nests of the water rail (Rallus aquaticus) and the little crake (Porzana parva). Broods of both rallids were simulated by real and wax-filled quail (Coturnix coturnix) eggs coloured typically for each species. Three grades of nest concealment were used: uncovered nests located on wooden floating boards, nests hidden in littoral vegetation and nests hidden under a plastic mesh covered with plants, which made them invisible from the air. Concealment proved to have a stronger impact on the fate of artificial nests than water depth; 95% of the nests on boards were depredated after one week of exposure. Nests attached to a peg at water level and hidden in vegetation had survival rates of 18 and 22%, after three weeks of exposure in two experiment repetitions. In 2012, we found significant differences between survival rates of nests located in different types of vegetation after the first week of the experiment: nests in bulrush (Typha spp.) had a higher survival rate than nests in sedge (Carex spp.) and common reed (Phragmites australis), and nests in sedge had a better survival rate than nests in reed. Those differences disappeared after the end of the experiment. In 2013, nests located in sedge (Carex spp.) had a better survival rate than nests located in bulrush (Typha spp.) or the common reed (Phragmites australis). Covering nests with plastic mesh and plants increased nest survival up to 38% after a three-week-long exposure period. Potential nest predators were monitored: mammals (mustelids and rodents) using live traps and birds by observation of their hunting activity. Filling quail eggshells with wax allowed us to identify the marsh harrier (Circus aeruginosus) as the main nest predator — in 67% of depredated nests, wax eggs carried marks of a raptor beak. American mink (Neovison vison) and the water vole (Arvicola amhibius), though abundant in the study area, were not important nest predators, as only a few bite marks of these mammals were recorded.

12

Free-living interstitial Plathelminthes of the Baltic Sea: diversity and abundance

58%

Urban-Malinga B.

Polish Journal of Ecology

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2011

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tom 59

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nr 3

EN

Free-living Plathelminthes constitute an important component of meiobenthic communities in various marine benthic environments, but research focusing on this group is generally scarce. The current study investigated the free-living interstitial flatworms of the shallow sandy sublittoral zone of the southern Baltic coast. Sediment samples were taken at Hel Peninsula at water depths of 1.5 m and 7 m, and the plathelminths were identified alive to the species level. In total, 22 species were identified. The majority of the species belonged to Kalyptorhynchia and Proseriata, but Acoela recently moved from Plathelminthes into their own phyllum and represented by Mecynostomidae, was the most numerous group. The average total plathelminth densities ranged between 6 and 74 ind. 10 cm–2. The vertical distribution of the plathelminth fauna in the sediments was usually limited to the upper 3–4 cm, except for acoels which penetrated deeper into the sediment layers. The role of both sediment water saturation and oxygen availability appeared to be the main factors limiting flatworm occurrence in the sediments investigated in this study.

13

Badania morfometryczne wydm piaszczystych o prostej linii szczytu zaobserwowanych na dnie ujsciowego odcinka rzeki Raby

51%

Slowik-Opoka E. , Radecki-Pawlik A.

Acta Scientiarum Polonorum. Formatio Circumiectus

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2007

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tom 06

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nr 1

43-54