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Wyświetlanie 1-10 z 27
Tytuł:
Key Species of Phytoplankton in Eastern Part of Segara Anakan Indonesia Based on Season
Autorzy:
Piranti, Agatha Sih
Setyaningrum, Nuning
Widyartini, Dwi Sunu.
Ardli, Erwin Riyanto
Tematy:
phytoplankton
Segara Anakan
spatial variation
temporal variation
Pokaż więcej
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Powiązania:
https://bibliotekanauki.pl/articles/1839175.pdf  Link otwiera się w nowym oknie
Opis:
Phytoplankton blooms are a problem that often occurs in estuarine and coastal ecosystems. The changes in phytoplankton community species composition, diversity, biomass, and distribution were caused by the conditions of seasonal and temporal variation. The immediate location of the estuary ecosystem is near cities, where rapid economic growth and human activity tends to increase the pressure on the environment. The purposes of this research were to evaluate the seasonal and temporal variation and to determine the key species of phytoplankton in the eastern part of Segara Anakan which can cause a bloom based on season. The samples of phytoplankton were taken from 6 sites during April – September 2019 when the highest tide occurred during the dry and rainy seasons. The community structure were performed using primer software Ver 5 to find the similarity and / or differences of the phytoplankton community structure based on season. Simper analysis was used to determine key species (phytoplankton species) based on season and location. The community structure of phytoplankton in Segara chicks were composed by 5 divisions. During the dry season, Bacillariophyta was dominant (82%), whereas during the rainy season, Bacillariophyta (43%) and Chlorophyta (31%) and Cyanophyta (25%) were the dominant species. This study shows that the phytoplankton community structure in this estuary presents the environment conditions during the rainy season that increase the abundance of phytoplankton, especially of the species which may thrive into blooms. The most important species was Oscillatoria limosa that had the highest percentage of contribution.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial variability of soil properties and cereal yield in a cultivated field on sandy soil
Autorzy:
Lipiec, Jerzy
Usowicz, Bogusław
Wydawca:
Elsevier B.V.
Cytata wydawnicza:
Usowicz, Boguslaw & Lipiec, J. (2017). Spatial variability of soil properties and cereal yield in a cultivated field on sandy soil. Soil and Tillage Research, 174. 10.1016/j.still.2017.07.015.
Opis:
European Commission
Sandy soils are used in agriculture in different regions of the world. In Poland soils derived from sands occupy about 50% of agricultural area. Productivity of the soils depend on the soil properties that vary in the scale of field. This study aimed at determining and mapping the within-field variation of soil physical and chemical properties and grain yield of oats, rye, oats and triticale in 2001, 2002, 2003, 2015, respectively. The experiment was set up in a field (200 ×50 m) on sandy soil in Trzebieszów (region Podlasie, Poland). The soil measurements included sand, silt, clay, and organic carbon (SOC) contents, cation exchange capacity (CEC), pH in the topsoil (0–10 cm) and subsoil (30–40 cm) layers in 2001, and water content and bulk density in the topsoil layer in spring and summer 2002–2003. The yields of oats were assessed in 2001 and 2003 and those of rye and triticale in 2002 and 2015, respectively. The soil properties and cereal yields were determined at 33–55 points in a grid evenly covering the whole field area. The results were analyzed using classic statistics and geostatistics by constructing semivariograms and 2D mapping by Inverse Distance Weighting (IDW). The cereal grain yields were significantly positively correlated with the topsoil water content (SWC) (r=0.295–0.711), clay content (r =0.081–0.174), and SOC in the subsoil (r= 0.208–0.271) and CEC in both layers (r=0.123–0.298) and negatively correlated with bulk density (BD) (r= –0.065 to−0.279). The spatial dependence determined by the “nugget-to-sill” ratio was moderate or weak for the silt and clay content, CEC, and pH (29–79%) and strong for SOC, BD, SWC, and crop yield (0.2–13.2%). The effective range of the spatial dependence for all studied quantities varied from 9.9 to 120 m. The cereal yields were positively and significantly correlated between all study years (r =0.141–0.734), which indicates inter-annual similarity in their spatial distribution. The 2D maps based on the IDW allowed assessing how gradual or sharp the changes in the studied quantities from one place to another are. Similar spatial patterns of the SWC, SOC and CEC, and crop yields were observed. This is of importance in precise and sustainable field management aimed at increasing and aligning spatial crop productivity of the studied low-productivity sandy soils that will have to be used in crop production due to the current shortage of land resources and food supplies on a global scale.
Dostawca treści:
Repozytorium Centrum Otwartej Nauki
Artykuł
Tytuł:
Seasonal variability of benthic ammonium release in the surface sediments of the Gulf of Gdańsk (Southern Baltic Sea)
Autorzy:
Maksymowska-Brossard, D.
Piekarek-Jankowska, H.
Tematy:
ammonium
spatial variation
seasonal variation
Baltic Sea
sediment
Gdansk Gulf
benthic flux
benthic ammonium
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Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/48426.pdf  Link otwiera się w nowym oknie
Opis:
This paper describes the seasonal and spatial variations of diffusive sediment– water ammonium fluxes in the western part of the Gulf of Gdańsk (southern Baltic). It assesses the potential environmental controls of these fluxes, such as the inflow of organic matter to bottom sediments and its quality, temperature-induced degradation of organic matter, and the redox potential of sediments. Ammonium fluxes, calculated using Fick’s first law, were always in the direction from the sediment into the water column and differed significantly with respect to sediment type. Fluxes were most intensive in sediments with the highest silt-clay fraction located in the deepest parts of the study area. The mean annual diffusive fluxes of ammonium from sediments to near-bottom water were estimated at 5.24 tonnes km−2 year−1 for silty-clays, 1.85 tonnes km−2 year−1 for silty-sands and 1.03 tonnes km−2 year−1 for sandy sediments. There was a high seasonal variation, with the greatest ammonium release in summer and early autumn, when the temperature of near-bottom water was the highest. On the basis of the calculated diffusive ammonium fluxes, we estimated that approximately 2700 tonnes of N–NH+4 are released annually from the surface sediments of the western part of the Gulf of Gdańsk, providing a minimum of 10% of the mineral nitrogen essential for primary production in surface waters. Our results are undoubtedly underestimated, as we disregarded advective ammonium fluxes, which in some areas of the Gulf of Gdańsk could well be comparable to diffusive fluxes.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of diatom and dinoflagellate cell volumes from surface waters of the Northern Indian Ocean
Autorzy:
Chitari, R.R.
Anil, A.C.
Tematy:
diatom
dinoflagellate
cell size
surface water
microphytoplankton
seasonal variation
spatial variation
Indian Ocean
Bengal Bay
Arabian Sea
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Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/47851.pdf  Link otwiera się w nowym oknie
Opis:
Phytoplankton samples collected from the Northern Indian Ocean (Bay of Bengal, northern Arabian Sea, and Dona Paula Bay Goa, west coast of India), were utilized to quantify changes in cell size, cell volume and carbon per cell of diatoms and dinoflagellates. The dataset from the Bay of Bengal also provides inter- and intra-annual variations (April 2008 to March 2010). The variations in cell size and volume were large in regions influenced by the riverine influx or terrigenous inputs. An interregional comparison of commonly available forms (8 species) points out that cell volumes are highest in the North Atlantic and lowest in the Mediterranean. The information provided will be useful in estimation of carbon biomass and biogeochemical studies.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of spatial variation of spoil material properties on slope displacements under rapid drawdown of pit lakes
Wpływ przestrzennego zróżnicowania właściwości materiału zwałowego na przemieszczenia zboczy w warunkach gwałtownego spiętrzenia wód zbiorników poeksploatacyjnych
Autorzy:
Halder, Koushik
Doan, Nhat-Phi
Garala, Thejesh Kumar
Cui, Ge
Kantesaria, Naman
Heron, Charles M.
Marshall, Alec M.
Tematy:
slope stability
spoil
spatial variation
numerical modelling
stateczność zboczy
zwałowisko
zmienność przestrzenna
modelowanie numeryczne
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Wydawca:
Poltegor-Instytut Instytut Górnictwa Odkrywkowego
Powiązania:
https://bibliotekanauki.pl/articles/2175667.pdf  Link otwiera się w nowym oknie
Opis:
In many European countries, lignite or brown coal is used as a fuel source in steam-electric power generation. Upon completion of mining activities, a reclamation plan is imperative to ensure environmental and social prosperity of local areas. Abandoned mine pits are often reclaimed by creating a pit lake. Reclamation of large lignite open pit mine sites may use large amounts of previous overburden materials or “spoils” to create the slopes of the pit lake. Spoils are anthropogenic materials with large spatial variation in properties, hence, considering mean values of shear strength and hydraulic parameters to assess stability and seasonal displacements will not fully simulate actual field conditions. This paper considers the effect of spatial variation on slope stability and ground movements during rapid drawdown events (a critical case) using coupled flow-deformation 2D finite element analyses, incorporating unsaturated soil suctions above the phreatic surface. Effects of heterogeneity and randomness of spoils on the response of the slope are considered through random field modelling and the Monte-Carlo simulation technique. Four lognormally distributed random variables (spoil cohesion, friction angle, void ratio, and permeability coefficient) are examined. The effect of spatial variability of spoils is shown to be important; a significant number of the random field analyses resulted in larger displacements compared to a benchmark deterministic analysis adopting uniform mean parameter values.
W wielu krajach europejskich węgiel brunatny jest wykorzystywany jako źródło paliwa w energetyce parowo-elektrycznej. Po zakończeniu działalności górniczej konieczne jest opracowanie planu rekultywacji w celu zapewnienia środowiskowego i społecznego dobrostanu okolicznych obszarów. Opuszczone wyrobiska górnicze są często rekultywowane poprzez utworzenie w nich zbiorników wodnych. W rekultywacji dużych kopalni odkrywkowych węgla brunatnego do tworzenia zboczy zbiornika można wykorzystać duże ilości wcześniejszych materiałów nadkładowych lub „odpadowych”. Materiał zwałowy jest materiałem antropogenicznym o dużej przestrzennej zmienności właściwości, dlatego też przyjęcie średnich wartości wytrzymałości na ścinanie i parametrów hydraulicznych w celu oceny stabilności i sezonowych przemieszczeń nie będzie w pełni odzwierciedlać rzeczywistych warunków terenowych. W niniejszej pracy rozważano wpływ zmienności przestrzennej na stabilność zboczy i przemieszczenia gruntu podczas gwałtownego obniżenia poziomu wody (przypadek krytyczny), stosując sprzężone analizy 2D metodą elementów skończonych typu przepływ-deformacja, z uwzględnieniem ssania gruntów nienasyconych powyżej powierzchni freatycznej. Wpływ heterogeniczności i losowości materiału na zachowanie zbocza rozważany jest poprzez modelowanie pola losowego i technikę symulacji Monte-Carlo. Badane są cztery zmienne losowe (kohezja materiału, kąt tarcia, wskaźnik porowatości i współczynnik przepuszczalności) w rozkładach log-normalnych. Wykazano, że wpływ przestrzennej zmienności materiału zwałowego jest istotny; znaczna liczba analiz z wykorzystaniem pola losowego skutkowała większymi przemieszczeniami w porównaniu z wzorcową analizą deterministyczną, w której przyjęto jednolite średnie wartości parametrów.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial and interannual variations of seasonal sea surface temperature patterns in the Baltic Sea
Autorzy:
Bradtke, K.
Herman, A.
Urbanski, J.A.
Tematy:
spatial variation
interannual variation
sea surface temperature
seasonality
global climate change
thermal season
annual cycle
transitional period
Baltic Sea
Pokaż więcej
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Powiązania:
https://bibliotekanauki.pl/articles/48507.pdf  Link otwiera się w nowym oknie
Opis:
On the basis of monthly averaged satellite data, this study examined how the annual cycle of the Baltic Sea surface temperature (SST) varied spatially and temporally during the period 1986–2005. We conclude that there are two main thermal seasons in the Baltic Sea separated only by short transitional periods – spring lasting about one month, and autumn lasting two months. Generally speaking, summer covers the part of the year from June to October with the highest monthly mean SST in August. Winter, with a minimum monthly mean SST in February in shallow waters or in March in deeper areas, lasts from December to April. As a result of climate changes over the Baltic Sea region, strong positive trends in SST occur in the summer months. In consequence, the period with extremely high sea surface water temperatures has become slightly longer in the central Baltic. In the last decade winter changes in SST display zero or even negative tendencies. The investigated period was characterized by an annual increase in mean temperatures of about 0.03–0.07◦C. However, the rates of monthly mean SST changes were sometimes more than three times as high.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of the spatialisation of water-sounds sequences on the perception of traffic noise
Autorzy:
Li, Jian
Maffei, Luigi
Pascale, Aniello
Masullo, Massimiliano
Tematy:
spatial variation
water sound
traffic noise
informational masking
zróżnicowanie przestrzenne
dźwięk wody
hałas komunikacyjny
maskowanie informacyjne
Pokaż więcej
Wydawca:
Politechnika Poznańska. Instytut Mechaniki Stosowanej
Powiązania:
https://bibliotekanauki.pl/articles/2146671.pdf  Link otwiera się w nowym oknie
Opis:
In the last decades, different researchers have shown the positive effects of informational masking (IM) on mitigating traffic noise perception and improving the local soundscape in urban parks. Most of these studies have tested various water sounds at different signal-to-noise ratios to optimise the selection and the sound levels to set the water sounds playback. However, less is known about the effects of the spatial distribution and movement of water sounds on the perception of the surrounding environment. Three different water-sounds sequences, and one control condition with only traffic noise, were created and used in an online experiment to investigate the role of spatialisation of water-sounds sequences. The sequences include a frontal fixed-position water sound, a two-position switching water sound and a four-position-randomised moving water sound. All of them were superimposed with a background traffic noise. Thirty-six subjects participated and answered an online questionnaire consisting of sets of items to describe the sound’s perception and feeling. The Perceived Restorativeness Scale (PRS-11) was also administered. The results have shown that introducing water-sounds sequences improves some components of the restorative qualities (Fascination and Being-Away). Moreover, different spatialisation settings of water sounds proved to modify people’s perception and feelings in different aspects, including attractiveness, smoothness, mechanicalness, stimulation, and nervousness.
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 27

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