Search results for "Silt"
showing 10 items of 98 documents
Reconstruction of palaeovegetation and sedimentation conditions in the area of ancient Lake Burtnieks, northern Latvia
2010
Palaeobotanical investigations were carried out with the aim of reconstructing the development of palaeovegetation and formation of sediments in the northeastern area of ancient Lake Burtnieks. Pollen and plant macroremain studies provide information on vegetation development in the surroundings of the lake, including Stone Age settlements of Braukšas I and Braukšas II. Results of the investigations indicate that the development of vegetation together with sedimentation conditions in the palaeolake have changed since the Younger Dryas until today. Vegetation composition varies in different parts of the ancient Lake Burtnieks area due to past changes in lake water level which reached differe…
Tēva piesaiste ar saviem vecākiem bērnībā saistībā ar pašreizējām tēva-bērna piesaistes attiecībām
2021
Tēva-bērna piesaistes attiecības ir maz pētīts lauks psiholoģijā, lielākajai daļai pētījumu šajā jomā ir par mātes-bērna piesaistes attiecībām. Šajā pētījumā, Latvijas izlasē, tika aptaujāti 50 tēvi, kuriem ir bērns 4-12 gadu vecumā. Šie tēvi aizpildīja Attiecību aptauju (Relationship Questionnaire, Bartholomew & Horowiz, 1991), kuru rezultāti atspoguļo tēva piesaistes stilu, un Vecāku audzināšanas pieeju aptauju (Block’s Child Rearing Practices Report; Block, 1980), lai noskaidrotu tēva audzināšanas pieejas. Šajā pētījumā tēva izrādītais emocionālais siltums savā audzināšanas pieejā tiks lietots kā norāde uz pozitīvām piesaistes attiecībām ar saviem bērniem. Tika veikta datu korelāciju ana…
Application of time domain induced polarization to the mapping of lithotypes in a landfill site
2012
A direct current (DC) resistivity and time domain induced polarization (TDIP) survey was undertaken at a decommissioned landfill site situated in Hørløkke, Denmark, for the purpose of mapping the waste deposits and to discriminate important geological units that control the hydrology of the surrounding area. It is known that both waste deposits and clay have clear signatures in TDIP data, making it possible to enhance the resolution of geological structures compared to DC surveys alone. <br><br> Four DC/TDIP profiles were carried out crossing the landfill, and another seven profiles in the surroundings provide a sufficiently dense coverage of the entire area. The whole dataset w…
Mineralogical and chemical variability of fluvial sediments 2. Suspended-load silt (Ganga–Brahmaputra, Bangladesh)
2011
Sediments carried in suspension represent a fundamental part of fluvial transport. Nonetheless, largely because of technical problems, they have been hitherto widely neglected in provenance studies. In order to determine with maximum possible precision the mineralogy of suspended load collected in vertical profiles from water surface to channel bottom of Rivers Ganga and Brahmaputra, we combined Raman spectroscopy with traditional heavy-mineral and X-ray diffraction analyses, carried out separately on low-density and dense fractions of all significant size classes in each sample (multiple-window approach). Suspended load resulted to be a ternary mixture of dominant silt enriched in phyllosi…
Gāzu hromatogrāfijas metodes validācija kvantitatīvai siltumnīcefekta gāzu noteikšanai gaisa paraugos
2021
Gāzu hromatogrāfijas metodes validācija siltumnīcefekta gāzu kvantitatīvai noteikšanai gaisa paraugos. Kuzņecova D., darba vadītāji: Mg.chem. L.Buša, Mg. silv. A.Butlers, LVMI Silava zinātniskais asistents. Bakalaura darbs , 31 lappuses, 6 tabulas, 9 attēli, 33 literatūras avoti, 7 pielikumi. latviešu valodā. Darba ir veiktā metodes validācija SEG gāzu kvantitatīvai noteikšanai. Bakalaura darba ietvaros tika izmantots gāzu hromatogrāfs Shimadzu Nexis GC-2030 ar kuru tika testēti 495 standartgāzu maisījumi un 736 paraugu, lai atrāstu optimālus instrumenta iestatījumus
Mineralogical and chemical variability of fluvial sediments: 1. Bedload sand (Ganga–Brahmaputra, Bangladesh)
2010
This study investigates the natural processes that control concentration of detrital minerals and consequently chemical elements in river sand. The novelty of our approach consists in the systematic integration of detailed textural, petrographical, mineralogical and chemical data, and in the quantitative description and modeling of relationships among mineralogical and chemical variables for each sample and each grain-size class in each sample. Bed sediment in transit in the largest sedimentary system on Earth chiefly consists of fine-grained lithofeldspatho quartzose sand including rich amphibole–epidote–garnet suites, mixed with minor very-fine grained-sand to silt subpopulations containi…
Life cycle environmental assessment of retaining walls in unsaturated soils
2022
Abstract Retaining structures above groundwater level support soils that are usually in a state of partial saturation and subject to the actions of atmospheric agents. The current design approach considers the possible extremes of soil conditions – either totally dry or totally saturated – but it neglects matric suction’s contribution to soil shear strength. This work aims to describe how unsaturated-soil mechanics of can positively influence the sustainability of retaining structures through a holistic, multidisciplinary, geotechnical, and environmental analysis. The geotechnical analysis allows to estimate the lateral earth pressure of a geostructure in both unsaturated and extreme soil c…
Cs2 molekulas A~b kompleksa augstas izšķirtspējas spektroskopiskie pētījumi un elektroniskās struktūras analīze
2019
Šajā maģistra darbā veikts Cs2 molekulas 〖A^1∑〗_u^+ un 〖b 〗^3 Π_u stāvokļu kompleksa elektroniskās-svārstību-rotācijas struktūras pētījums pielietojot Furjē transformāciju spektroskopijas un lāzera inducētās fluorescences (LIF) metodes. 〖A^1∑〗_u^+ un 〖b 〗^3 Π_u stāvokļus raksturo spēcīga spin-orbitālā mijiedarbība, kuras rezultātā stāvokļi veido saistītu A~b kompleksu. Cs2 molekulas pētīšanai maģistra darbā pielietota LIF metode, izmantojot dažādas lāzeru sistēmas, kombinācijā ar Furjē transformāciju spektrometru (Bruker IFS-125HR). Eksperimentāli reģistrēti un analizēti Cs2 molekulas spektri pārejās no A~b kompleksa uz pamatstāvokli. Darbā aprakstīts spektru apstrādes process, kura rezultā…
Amusium cristatum shell beds in the lower Pliocene deposits of Almería-Níjar Basin (SE Spain)
2020
Densely packed monospecific-paucispecific Amusium cristatum-dominated shell beds are signifi cant features in the lower Pliocene deposits of the Almeria-Nijar Basin (SE Spain), embedded in distal prodelta fi ne-grained sand and silt. The shells in these concentrations are exceptionally well preserved: articulation is relatively high, fragmentation is low, abrasion is almost lacking, and many shells preserve the original colour pattern. These taphonomic signatures suggest in situ deposition forming autochthonous fossil assemblages, i.e. biological concentrations. Benthic foraminiferal assemblages found in the prodelta deposits indicate that they formed in mesotrophic mid-shelf settings.The A…
Characterization of organic matter in topsoils under rain forest and pasture in the eastern Brazilian Amazon basin
1999
In topsoils under forest and 7-, 12- and 17-year-old pastures, organic matter was characterized by analysing C and N distribution in particle-size fractions, the C decomposition rates of soil and particle-size fractions and by employing density-fractionation of macro-organic matter (>150 μm). The C and N associated with clay fractions increased with increasing age of pasture. The weight (%) of macro-organic matter and its heavy fractions (>1.37 g cm–3) also increased with increasing age of pasture. However, in a long-term incubation (100 days), these changes seemed to involve an increase in the C decomposition rate in the topsoil of the oldest pasture. Using the C decomposition rates of par…