Search results for "Sediment"
showing 10 items of 1648 documents
Interlake variation and environmental controls of denitrification across different geographical scales
2013
Denitrification in lakes significantly reduces the nitrogen (N) load from land to oceans, but the factors controlling it remain poorly under- stood. Therefore, interlake variation of denitrification in sediments of small to medium-sized lakes (from 0.03 to 17.8 km 2 ) was studied across different geo- graphical scales. At the local scale, the denitrification rates and sediment microbial communities were studied in 4 boreal lakes in close proximity (within 20 km) using the isotope pairing technique (IPT) and molecular methods. These local scale data were com- bined with previously published data on denitrifica- tion rates from 10 other European lakes to extend the analysis to the regional (b…
Spatial and temporal variation in denitrification and in the denitrifier community in a boreal lake
2011
We investigated the spatial and temporal variation in denitrification rates (isotope-pairing technique, IPT) and in the denitrifier community (examination of gene nirK by denaturing-gradient gel electrophoresis [DGGE] of microbial DNA) in the sediments of a boreal, clear-water, eutrophic lake using samples collected from shallow littoral, deep littoral and shallow profundal sediments during early summer, mid-summer, autumn and winter. The measured denitrification rates (44 to 613 µmol N m−² d−¹) are among the lowest ever reported from lacustrine sediments. Denitrification rates varied both spatially and temporally, being highest in the profundal zone during mid-summer and in the littor…
Spatial and temporal variation in denitrification and in the denitrifier community in a boreal lake
2011
We investigated the spatial and temporal variation in denitrification rates (isotopepairing technique, IPT) and in the denitrifier community (examination of gene nirK by denaturinggradient gel electrophoresis [DGGE] of microbial DNA) in the sediments of a boreal, clear-water, eutrophic lake using samples collected from shallow littoral, deep littoral and shallow profundal sediments during early summer, mid-summer, autumn and winter. The measured denitrification rates (44 to 613 μmol N m−2 d−1) are among the lowest ever reported from lacustrine sediments. Denitri fi - cation rates varied both spatially and temporally, being highest in the profundal zone during midsummer and in the littoral z…
Nitrogen removal by microbial processes in aquatic systems
2012
Environmental control on granular clinoforms of ancient carbonate shelves
2006
The purpose of this paper is to document the influence of depositional environments on shallow-water, low-relief clinoforms from the description of five ancient carbonate platforms: the Neoproterozoic (Namibia), Middle Jurassic (France), Lower Cretaceous (France), Upper Cretaceous (Oman) and Miocene (Turkey). These examples have been investigated on the basis of field observations. The clinoforms are described with reference to geometric and compositional attributes: declivity, shape, height, sedimentary structures, sediment fabric and components. The results show great variability in stratal geometry, declivity and facies distribution: (1) depositional profiles vary from exponential, to si…
Tectonically-enhanced deposition in the Late Tortonian Scillato Basin (N Sicily): a sequence stratigraphic view
2010
Mesozoic discontinuities in the Panormide Carbonate Platform: constraints on the palaeogeography of the central Mediterranean
2008
Pēdu fosiliju kompleksi galvenā devona lauka Franas stāva nogulumos
2013
ANOTĀCIJA Promocijas darbā analizēts pēdu fosiliju komplekss Franas stāva nogulumos Galvenajā devona laukā. Balsttes uz ievākt un notikt ihnofosiliju matriālu, tka izveidota sistmātskā ihnoloģija, pēc kuras analīzes nodalītas ihnokompleksu grupas un ihnofācijas. Iegūte dat ļāva papildināt iepriekš pastāvošos priekšstatus par Galvenā devona lauka Franas stāva nogulumos pārstāvēt organismu grupu daudzveidību, intrpretēt faciālo apstākļu mainību un paleoekoloģiskos apstākļus Baltjas devona baseinā Franas laikmetā. Galvenā devona lauka Franas stāva nogulumos dominējošās ihnofācijas norāda uz seklas jūras sedimentācijas vidi un mainīgiem faciālajiem apstākļiem. Pētījumā tka konstatēta ihnofosili…
Effect of substrate particle size on burrowing of the juvenile freshwater pearl mussel Margaritifera margaritifera
2021
AbstractJuveniles of the endangered freshwater pearl mussel (FPM,Margaritifera margaritifera) live burrowed in stream substrate for the first years of their life. Fine sediments block water exchange within substrate and may cause juvenile mortality and recruitment failure. To better understand the connection between success of juvenile FPM and substrate particle size, it would be important to understand behavioural responses of FPM to varying substrate sizes at this critical life stage. We placed newly detached FPM juveniles in a 7-mm layer of sieved sand sorted into five sizes (< 120, 120–200, 200–250, 250–500 and 500–650 µm) each with 10 replicate dishes, 10 juveniles per dish, with bu…
Natural Laboratories for Field Observation About Genesis and Landscape Effects of Palaeo-Earthquakes: a Proposal for the Rocca Busambra and Monte Bar…
2018
Earthquakes are phenomena that are still being learned by the scientific community, and poorly known, especially as regards the prevention, by the population. Having a more complete knowledge is a basic step in understanding the vastness and intensity of the destructive phenomenon that involves a great amount of people. The recent earthquakes occurred in Central Italy (L’Aquila and Amatrice earthquakes) are examples that demonstrate the importance of having knowledge about these phenomena to contrast their destructive effects. We present a geological field trip to recognise causes and landscape effects of palaeo-earthquakes recorded in the Mesozoic rock successions outcropping in Sicily. Th…