Search results for "lake"
showing 10 items of 369 documents
A practical methodology to perform global sensitivity analysis for 2D hydrodynamic computationally intensive simulations
2021
Sensitivity analysis is a commonly used technique in hydrological modeling for different purposes, including identifying the influential parameters and ranking them. This paper proposes a simplified sensitivity analysis approach by applying the Taguchi design and the ANOVA technique to 2D hydrodynamic flood simulations, which are computationally intensive. This approach offers an effective and practical way to rank the influencing parameters, quantify the contribution of each parameter to the variability of the outputs, and investigate the possible interaction between the input parameters. A number of 2D flood simulations have been carried out using the proposed combinations by Taguchi (L27…
A 5500-year oxygen isotope record of high arctic environmental change from southern Spitsbergen
2017
The oxygen isotope composition of chironomid head capsules in a sediment core spanning the past 5500 years from Lake Svartvatnet in southern Spitsbergen was used to reconstruct the oxygen isotope composition of lake water (δ18Olw) and local precipitation. The δ18Olw values display shifts from the baseline variability consistent with the timing of recognized historical climatic episodes, such as the Roman Warm Period, the Dark Ages Cold Period and the ‘Little Ice Age’. The highest values of the record, ca. 3‰ above modern δ18Olw values, occur at ca. 1900–1800 cal. yr BP. Three negative excursions increasing in intensity toward the present, at 3400–3200, 1250–1100, and 350–50 cal. yr BP, are…
Towards a dendrochronologically refined date of the Laacher See eruption around 13,000 years ago
2020
Highlights • Previous age estimates of the Laacher See Eruptions (LSE) around 12,900 years are still diverging and imprecise. • The combination of dendrochronology, wood anatomy, and 14C measurements holds the potential to establish a precise LSE date. • An absolute calendric date of the LSE would improve the synchronization of European Late Glacial to Holocene archives. Abstract The precise date of the Laacher See eruption (LSE), central Europe’s largest Late Pleistocene volcanic event that occurred around 13,000 years ago, is still unknown. Here, we outline the potential of combined high-resolution dendrochronological, wood anatomical and radiocarbon (14C) measurements, to refine the age …
CONCESSIONI DEMANIALI MARITTIME E DIRITTO EUROUNITARIO: LA FINE DEL TEMPO DELLE MORE
2023
Il contributo analizza il frammentario quadro normativo delle concessioni demaniali marittime, lacuali e fluviali con finalità turistico-ricreativa alla luce degli orientamenti della giurisprudenza domestica, con le significative pronunce del Consiglio di Stato e di quella della Corte di Giustizia dell’Unione europea, in particolare della recentissima sentenza 20 aprile 2023 (C-348/22).
Terrestrial carbon and intraspecific size-variation shape lake ecosystems
2007
Conceptual models of lake ecosystem structure and function have generally assumed that energy in pelagic systems is derived from in situ photosynthesis and that its use by higher trophic levels depends on the average properties of individuals in consumer populations.These views are challenged by evidence that allochthonous subsidies of organic carbon greatly influence energy mobilization and transfer and the trophic structure of pelagic food webs, and that size variation within consumer species has major ramifications for lake communitydynamics and structure. These discoveries represent conceptual shifts that have yet to be integrated into current views on lake ecosystems. Here, we assess k…
Vertical distribution of pharmaceuticals in lake sediments-citalopram as potential chemomarker
2012
The use of pharmaceuticals has increased enormously over the last few decades and serious concerns about their environmental fate and effects have arisen. Thus far, there is little knowledge about the historical pollution of the environment by pharmaceuticals. In the present study, sediment columns from three lake sites adjacent to wastewater treatment plants were collected, further divided in 2- or 2.5-cm slices, and analyzed for 15 pharmaceuticals by liquid chromatography-tandem mass spectrometry. In addition, sediment columns were historically interpreted by analyzing fecal sterols (coprostanol and cholesterol) as well as organic material and organic carbon. Several pharmaceuticals were …
Regional climate model simulations for Europe at 6 and 0.2 k BP: sensitivity to changes in anthropogenic deforestation
2014
International audience; This study aims to evaluate the direct effects of anthropogenic deforestation on simulated climate at two contrasting periods in the Holocene, ∼ 6 and ∼ 0.2 k BP in Eu-rope. We apply the Rossby Centre regional climate model RCA3, a regional climate model with 50 km spatial resolution, for both time periods, considering three alternative descriptions of the past vegetation: (i) potential natural vegetation (V) simulated by the dynamic vegetation model LPJ-GUESS, (ii) potential vegetation with anthro-pogenic land use (deforestation) from the HYDE3.1 (History Database of the Global Environment) scenario (V + H3.1), and (iii) potential vegetation with anthropogenic land …
Short-period volcanic gas precursors to phreatic eruptions: Insights from Poás Volcano, Costa Rica
2016
Texto completo del documento Volcanic eruptions involving interaction with water are amongst the most violent and unpredictable geologic phenomena on Earth. Phreatic eruptions are exceptionally difficult to forecast by traditional geophysical techniques. Here we report on short-term precursory variations in gas emissions related to phreatic blasts at Poás volcano, Costa Rica, as measured with an in situ multiple gas analyzer that was deployed at the edge of the erupting lake. Gas emitted from this hyper-acid crater lake approaches magmatic values of SO2/CO21–6 days prior to eruption. The SO2flux derived from magmatic degassing through the lake is measureable by differential optical absorpti…
Sociālās un ekonomiskās ietekmes ezeru attīrīšanā un labiekārtošanā.
2015
Bakalaura darba „Sociālās un ekonomiskās ietekmes ezeru attīrīšanā un labiekārtošanā” mērķis ir izprast ezeru un to ekosistēmu nozīmīgumu, regulējošās un atbalsta funkcijas, izanalizēt sociālos un ekonomiskos ieguvumus veicot ieguldījumus ezera infrastruktūras un tur mītošo zivju sugu pavairošanas projektos. Bakalaura darba uzdevumos ietilpst ekosistēmu darbības principu apskate, šā brīža makšķerēšanas nozares un ezeru stāvokļa un to problēmu apzināšanās, kā arī ārzemēs veikto pētniecisko darbu analīze un aptaujas rezultātu analizēšana. Lai spētu sniegt ieteikumus Smiltenes ezeru attīrīšanas un labiekārtošanas plāna projekta realizēšanai, tiek izpētīts Katvaru ezera apsaimniekošanas modelis…
Invasive vascular plant species of oxbow lakes in south-western Poland
2015
Abstract Natural water reservoirs are very valuable floristic sites in south-western Poland. Among them, the most important for the preservation of biodiversity of flora are oxbow lakes. The long-term process of human pressure on habitats of this type caused disturbances of their biological balance. Changes in the water regime, industrial development and chemisation of agriculture, especially in the period of the last two hundred years, led to systematic disappearances of localities of many plant species connected with rare habitats and also to the appearance of numerous invasive plant species. They are: Azolla filiculoides, Echinocystis lobata, Erechtites hieraciifolia, Impatiens glandulif…