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1552. Efektívnosť ílových minerálov pri znižovaní vooodpudivosti počas dlhého suchého a teplého obdobia
- Creator:
- Lichner, Ľubomír and Dlapa, Pavel
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- water repellency, sand, stearic acid, clay minerals, vodoodpudivosť, piesok, kyselina stearová, and ílové minerály
- Language:
- Slovak
- Description:
- The aim of this study was to evaluate an efficiency of clay minerals (kaolinite, illite, Na- and Ca-montmorillonite) in alleviating the water repellency of stearic acid sand during the course of long-term hot and dry spell. This spell was simulated by prolonged drying (incubation) of the samples in oven at 50°C. It was found that the kaolinite addition resulted in a drop in the persistence of water repellency of the stearic acid sand. On the contrary, the Ca-montmorillonite addition increased markedly the persistence of water repellency of the stearic acid sand. In most cases, the illite addition resulted in an increase in the persistence of water repellency, even though not so markedly as it was in the case of Ca-montmorillonite addition. In the case of Na-montmorillonite addition, the striking drop in the persistence of water repellency of the stearic acid sand was registered only after lowering the moisture below 5 %. An increase in the persistence of water repellency of the sand-clay mixture with an increase in the clay amount is another interesting finding, observed in case of kaolinite and Ca-montmorillonite. and Cieľom tejto štúdie bolo zhodnotenie efektívnosti ílových minerálov (kaolinitu, illitu, Na- a Camontmorillonitu) pri znižovaní stálosti vodoodpudivosti piesku pokrytého kyselinou stearovou počas dlhého suchého a teplého obdobia, simulovaného inkubáciou vzoriek pri teplote 50 °C. Zistili sme, že pridanie kaolinitu výrazne znížilo stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou prakticky počas celého cyklu sušenia. Pridanie Ca-montmorillonitu naopak stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou výrazne zvýšilo. Pridanie illitu vo väčšine prípadov zvýšilo stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou, aj keď nie tak výrazne ako pridanie Ca-montmorillonitu. V prípade pridania Na-montmorillonitu sme výrazné zníženie vodoodpudivosti piesku pokrytého kyselinou stearovou zaznamenali až po poklese vlhkosti vzorky pod 5 %. Ďalším zaujímavým poznatkom je vzrast vodoodpudivosti so zvyšujúcim se obsahom ílu, ktorý sme zaregistrovali v prípade kaolinitu a Ca-montmorillonitu.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1553. Effect of climate warming on a change in thermal and ice conditions in the largest lake in Poland - Lake Śniardwy
- Creator:
- Ptak, Mariusz, Sojka, Mariusz, and Nowak, Bogumił
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- lakes, water temperature, air temperature, ice cover, climate change, and Central Europe
- Language:
- Slovak
- Description:
- Lake Śniardwy is the largest among more than 7000 Polish lakes. So far, it has not been a subject of detailed investigations concerning long-term changes in water temperature or ice regime. A considerable change in thermal and ice conditions has been observed in the period 1972–2019. Mean annual water temperature increased by 0.44°C dec–1 on average, and was higher than an increase in air temperature (0.33°C dec–1). In the monthly cycle, the most dynamic changes occurred in April (0.77°C dec–1). In the case of ice cover, it appeared increasingly later (5.3 days dec–1), and disappeared earlier (3.0 days dec–1). The thickness of ice cover also decreased (2.4 cm dec–1). Statistical analysis by means of a Pettitt test showed that the critical moment for the transformations of the thermal and ice regime was the end of the 1980’s. In addition to the obvious relations with air temperature for both characteristics, it was evidenced that the occurrence of ice cover depended on wind speed and snow cover. The recorded changes in the case of Lake Śniardwy are considered unfavourable, and their consequences will affect the course of physical, chemical, and biological processes in the largest lake in Poland.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1554. Effect of debris accumulation on scour evolution at bridge pier in bank proximity
- Creator:
- Palermo, Michele, Pagliara, Simone, and Roy, Deep
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- hydraulic model, large debris, local scour, and time evolution
- Language:
- Slovak
- Description:
- Large debris transported by flood affects scour features at bridge piers and increases the risks of structural failure. Geometric characteristics of the debris and the relative position of the pier with respect to the river bank are important parameters for the scour process. The interaction between the water flow and debris accumulation increases the shear stress, turbulence and consequently enhances the scour depth at the pier. This paper aims at analyzing such effects on scour evolution at bridge piers. To this end, two series of tests were carried out under clear water condition with different debris geometries and percentage blockage ratios. Experimental evidences showed that the pier position only influences scour evolution and equilibrium morphology for low water depths. Conversely, its effect becomes negligible for scour at bridge piers with debris accumulation and higher water depths. Useful practical relationships have been derived, with satisfactory prediction capability of the scour evolution for all the tested configurations.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
1555. Effect of drying on the sorption and desorption of copper in bottom sediments from water reservoirs and geochemical partitioning of heavy metals and arsenic
- Creator:
- Hiller, Edgar and Šutriepka, Michal
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- heavy metals, sorption, desorption, mobility, sequential extraction, dredged sediments, ťažké kovy, sorpcia, desorpcia, mobilita, sekvenčná extrakcia, and vyťažené sedimenty
- Language:
- Slovak
- Description:
- Bottom sediments can be significant sinks for a variety of heavy metals and metalloids coming from various anthropogenic sources. When these sediments are dredged and disposed of to land, drying and oxidation can lead to several changes in their physico-chemical properties, such as redox potential and pH, and hence to changes in metal mobility. Therefore, this work was conducted to study the adsorptiondesorption behaviour of one selected heavy metal - copper - in three bottom sediment samples before and after drying. Moreover, possible geochemical associations of As, Cd, Co, Cu, Hg, Ni, Pb and Zn in the airdried sediments were studied using a modified BCR sequential extraction protocol. Generally, redox state of the sediments changed from the highly anoxic to oxic and adsorption of Cu2+ decreased when the originally anoxic sediments were dried. On the other hand, the enhanced release of Cu2+ was observed from the air-dried sediments. The adsorption-desorption data showed that the changes in metal leachability occurred between originally anoxic and air dried sediments. In terms of water and soil pollution by Cu and likely other heavy metals, it appears that the dredged, air-dried sediments could represent somewhat greater contamination risks when compared with the originally anoxic sediments. Using the sequential extraction data, leaching potential of heavy metals and arsenic in the air-dried sediments was possible to evaluate with Cd, Co, Zn as the most mobile heavy metals, followed by Cu, Ni, As, Pb and Hg, respectively. and Dnové sedimenty sú významnými adsorbentmi celej rady ťažkých kovov a polokovov, ktoré pochádzajú z rôznych antropogénnych zdrojov. Po vyťažení týchto sedimentov z vodných nádrží na zemský povrch prechádzajú procesmi sušenia a oxidácie, ktoré menia niektoré ich vlastnosti, ako oxidačno-redukčný potenciál a pH, a teda môžu ovplyvňovať pohyblivosť potenciálne toxických kovov prítomných v sedimentoch. Z tohto dôvodu cieľom práce bolo štúdium adsorpcie a desorpcie jedného vybraného ťažkého kovu - medi - v troch vzorkách dnových sedimentov pred vysušením a po ňom. Okrem toho sme pomocou modifikovanej BCR metódy sekvenčnej extrakcie študovali možné geochemické interakcie ťažkých kovov (Cd, Co, Cu, Hg, Ni, Pb, Zn) a arzénu s jednotlivými zložkami dnových sedimentov. Ako ukázali experimentálne výsledky, počas sušenia sa zmenili redukčné podmienky v sedimentoch na oxidačné a adsorpčná kapacita vysušených sedimentov vzhľadom k Cu2+ bola výrazne nižšia ako u pôvodných sedimentov. Na druhej strane, množstvo uvoľneného Cu2+ z vysušených sedimentov bolo vyššie ako z pôvodných sedimentov. Uvedené zistenia teda poukazujú na zmenu v správaní a pohyblivosti potenciálne toxických prvkov medzi pôvodnými, redukčnými sedimentmi a tými, ktoré prešli procesom sušenia a oxidácie. Z hľadiska znečistenia prírodných vôd a pôd meďou a pravdepodobne aj ďalšími ťažkými kovmi sa zdá, že v porovnaní s pôvodnými kontaminovanými sedimentmi vyťažené a na vzduchu vysušené sedimenty môžu predstavovať vyššie riziko pre životné prostredie. Podľa výsledkov sekvenčnej extrakcie sa ukázalo, že Cd, Co a Zn sú po vysušení v skúmaných sedimentoch veľmi mobilnými prvkami, pričom pohyblivosť ostatných prvkov klesá v poradí Cu > Ni > As > Pb >> Hg.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1556. Effect of gravel content on soil water retention characteristics and thermal capacity of sandy and silty soils
- Creator:
- Beck-Broichsitter, Steffen, Haider Rizvi, Zarghaam, Horn, Rainer, and Wuttke, Frank
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- pore size distribution, soil water retention curve, thermal capacity, and PDI model
- Language:
- Slovak
- Description:
- The presence of gravel in soils modifies the porosity, pore connectivity and pore size distribution in the soil matrix as well as the soil matrix-gravel interfaces. The aim of the present study is to investigate the effect of relative volume of gravel in samples with gravel mass fractions of 5,10, 20 wt% and varying bulk densities (1.3, 1.45, 1.55, 1.60, 1.65 g cm–3) on (i) total porosity, field capacity, plant available water holding capacity, (ii) pore size distribution and (iii) thermal capacity of repacked sandy and silty soils. The focus of the study was to determine if laboratory measured soil water retention curves considering (i), (ii), and (iii) can be predicted by a gravel-based weighting factor, Rv, considering comprehensive significance tests. The sand-gravel mixtures show a decrease in the volume fractions of macropores and wide cores pores with an increase in the gravel contents, while the silt-gravel mixtures show an opposite trend. The root mean square errors (RMSE) between measured and fitted volumetric water contents, θ, between 0.006 and 0.0352 and between 0.002 and 0.004 for Rv-weighted volumetric water contents indicate that the van Genuchten-based Peters-Durner- Iden (PDI) model is appropriate for fitting. The soil water retention curves with mass gravel contents of up to 10 wt% for silt and 20 wt% for sand can be well predicted by weighting factors (relative volume of rock fragments) in the range between 0.045 and 0.058 for silt, and between 0.112 and 0.119 for sand. The results also indicate a decrease in the Rv-weighted saturated, cvsat, and dry, cvdry, thermal capacity with an increase in the gravel contents for both soils. Further investigations are needed to examine if and whether measured sand- and silt-gravel mixtures with mass gravel contents below 10 % or rather 20 % can be predicted with a weighting factor.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1557. Effect of mature spruce forest on canopy interception in subalpine conditions during three growing seasons
- Creator:
- Jančo, Martin, Mezei, Pavel, Kvas, Andrej, Danko, Michal, Sleziak, Patrik, Minďáš, Jozef, and Škvarenina, Jaroslav
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- precipitation, interception, synoptic types, Norway spruce (Picea abies L. Karst.), and growing season
- Language:
- Slovak
- Description:
- The interception process in subalpine Norway spruce stands plays an important role in the distribution of throughfall. The natural mountain spruce forest where our measurements of throughfall and gross precipitation were carried out, is located on the tree line at an elevation of 1,420 m a.s.l. in the Western Tatra Mountains (Slovakia, Central Europe). This paper presents an evaluation of the interception process in a natural mature spruce stand during the growing season from May to October in 2018–2020. We also analyzed the daily precipitation events within each growing season and assigned to them individual synoptic types. The amount and distribution of precipitation during the growing season plays an important role in the precipitation-interception process, which confirming the evaluation of individual synoptic situations. During the monitored growing seasons, precipitation was normal (2018), sub-normal (2019) and above-normal (2020) in comparison with long-term precipitation (1988–2017). We recorded the highest precipitation in the normal and above-normal precipitation years during the north-eastern cyclonic synoptic situation (NEc). During these two periods, interception showed the lowest values in the dripping zone at the crown periphery, while in the precipitation sub-normal period (2019), the lowest interception was reached by the canopy gap. In the central crown zone near the stem, interception reached the highest value in each growing season. In the evaluated vegetation periods, interception reached values in the range of 19.6–24.1% of gross precipitation total in the canopy gap, 8.3–22.2% in the dripping zone at the crown periphery and 45.7–51.6% in the central crown zone near the stem. These regimes are expected to change in the Western Tatra Mts., as they have been affected by windstorms and insect outbreaks in recent decades. Under disturbance regimes, changes in interception as well as vegetation, at least for some period of time, are unavoidable.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1558. Effect of microplastics on silty loam soil properties and radish growth
- Creator:
- Botyanszká, Lenka, Šurda, Peter, Vitková, Justína, Lichner, Ľubomír, and Igaz, Dušan
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- microplastics, silty loam soil, radish, and soil properties
- Language:
- Slovak
- Description:
- Microplastics (particles of plastics <5 mm) affect the physical, biological and hydrological properties of agricultural soil, as well as crop growth. We investigated the effect of the addition of three microplastics (high-density polyethylene (HDPE), polyvinyl chloride (PVC), and polystyrene (PS)) at a concentration of 5% (w/w) to a silty loam soil on selected soil properties and growth of radish (Raphanus sativus L. var. sativus). Changes in the soil properties and radish growth in three microplastic treatments were compared with the control. Soil properties (bulk density, hydraulic conductivity, sorptivity, water repellency) were estimated for each treatment at the beginning and at the end of the radish growing period (GP). The bulk density was significantly lower in the HDPE and PVC treatments compared to the control within the measurement at the beginning of the GP and in all microplastic treatments compared to the control at the end of the GP. The values of hydraulic conductivity and water sorptivity did not show significant differences between any treatments within the measurement at the beginning of GP, but they were significantly higher in the HDPE treatment compared to the control at the end of the GP. The growth of radish was characterized by the plant biomass and effective quantum yield of Photosystem II (Y (II)). We did not find a statistically significant difference in the total biomass of radish between any of the experimental treatments, maybe due to used concentration of microplastics. The mean value of Y (II) was significantly higher in all microplastic treatments compared to control only within the last measurement at the end of the GP. A statistically significant change of Y(II) in all microplastic treatments may indicate functional shift in soil properties; however, the measured values of the soil characteristics have not shown the significant changes (except for the bulk density values in all microplastic treatments and hydraulic conductivity together with sorptivity in HDPE treatment within the measurement at the end of GP).
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1559. Effect of river training on flood retention of the Bavarian Danube
- Creator:
- Skublics, Daniel, Blöschl, Günter, and Rutschmann, Peter
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- flood retention, flood plain, inundation areas, flood management, and hydrodynamic modelling
- Language:
- Slovak
- Description:
- The Bavarian Danube River has experienced numerous large flood events in recent years which make flood management an urgent matter. The propagation of flood waves along the river is heavily influenced by controlled and natural flood retention. Over the past centuries, natural flood retention areas were lost due to river training, and the hydraulic characteristics of the channel-flood plain system were modified. The purpose of this paper is to understand the effect of river training on the flood retention characteristics along the Bavarian Danube. Systematic two-dimensional hydrodynamic modelling shows that extreme floods are attenuated more strongly in the present state of the channel-flood plain system than they were historically. This is because the retention areas are filled later during the event, so the attenuation effect is much larger for the same magnitude of the retention volume. Natural flood retention is therefore not an effective management option for reducing extreme floods on the Bavarian Danube. Controlled flood retention measures provide a higher efficiency regarding peak attenuation to retention volume ratio. On the other hand, the delay of flood peaks due to natural retention may be beneficial for the superposition of the flood waves with contributions from downstream tributaries.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
1560. Effect of sand burial on the subcritical water repellency of a dominant moss crust in a revegetated area of the Tengger Desert, Northern China
- Creator:
- Jia, Rongliang, Gao, Yanhong, Liu, Lichao, Yang, Haotian, and Zhao, Yang
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- water repellency, sand burial, moss crust, and precipitation
- Language:
- Slovak
- Description:
- Sand burial is a ubiquitous disturbance that influences the ecological and hydrological properties of moss crusts in many sandy desert areas. There is little available information regarding the effect of sand burial on the water repellency (WR) of moss crusts in desert areas. Therefore, this study evaluated the effects of sand burial (sand depths of 0 (control), 0.5, 1, 2, 4 and 10 mm) followed by three simulated precipitation regimes (through applying 4 and 6 mm, 2 and 3 mm, and 1 and 1.5 mm of distilled water at 8-day intervals in spring and autumn, respectively) on the WR of a widespread moss crust dominated by Bryum argenteum Hedw. in a revegetated area of the Tengger Desert, China. The results showed moss crust WR remained subcritical during the whole experiment, and that it considerably decreased immediately after sand burial, even though the values of WR were significantly higher in autumn than those in spring under the same treatment (p < 0.05). Furthermore, the depth threshold (TD) values for sand burials that reduced WR to zero were 1 and 2 mm in spring and autumn, respectively. After a recovery period of nearly one-season (72 days), the WR of the moss crust significantly increased (p < 0.05). In addition, sand burial had two separate effects on moss crust WR. Specifically, shallower sand burial (burial depth less than 0.5 mm) increased moss crust WR, whereas deeper sand burial (burial depth exceeds 0.5 mm) decreased it. The TD values also significantly increased to 2 and 4 mm in spring and autumn, respectively. These findings about the effects of sand burial on moss crust WR provide additional information that can be used to better understand the influence of sand burial on moss crust colonization and maintenance in arid sandburial- stressed ecosystems, and to help explain why there are some contrasting viewpoints on biocrust WR.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public