Sökning: "trace fossil"

Visar resultat 6 - 10 av 18 avhandlingar innehållade orden trace fossil.

1. 6. Particulate and gaseous emissions from residential biomass combustion

   Författare :Christoffer Boman; Anders Nordin; Ingwald Obernberger; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemistry; aerosols; air pollution; emissions; fuel pellets; residential biomass combustion; inorganic characterization; incomplete combustion; particulate matter; polycyclic aromatic hydrocarbons; trace elements; Kemi; Chemistry; Kemi;

   Sammanfattning : Biomass is considered to be a sustainable energy source with significant potentials for replacing electricity and fossil fuels, not at least in the residential sector. However, present wood combustion is a major source of ambient concentrations of hydrocarbons (e.g. LÄS MER

3. 7. Long-term development of subalpine lakes : effects of nutrients, climate and hydrological variability as assessed by biological and geochemical sediment proxies

   Författare :Manuela Milan; Christian Bigler; Monica Tolotti; Richard Bindler; Krystyna Szeroczyńska; Atte Korhola; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Paleolimnology; diatoms; Cladocera; sub-fossil pigments; geochemistry; wavelengthdispersive X-ray fluorescence spectroscopy; Lake Garda; Lake Ledro; reference conditions; nutrient enrichment; climate change; hydrological regime.;

   Sammanfattning : Sediment records of two Italian subalpine lakes (Lake Garda and Lake Ledro) were analyzed in order to reconstruct their ecological evolution over the past several hundred years. A multi-proxy and multi-site approach was applied in order to disentangle the effects of local anthropogenic forcings, such as nutrients, and climate impacts on the two lakes and their catchments. LÄS MER

4. 8. Ocean chemistry and the evolution of multicellularity

   Författare :Emma U. Hammarlund; Stefan Bengtson; Donald Canfield; Nils Holm; Graham Budd; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geochemistry; biology; paleontology; evolution; multicellularity; geokemi; Geochemistry;

   Sammanfattning : Oxygen has been assumed to be a vital trigger for the evolution of multicellular life forms on Earth, partly based on its power to promote substantial energy flux in cell respiration and partly as biosynthesis of compounds like collagen require oxygen. However, the co-evolution of large life and the Earth’s chemical environment is not well understood at present, and there is particular disagreement in the field about whether the Cambrian explosion of animal life forms was a chemical or biological event. LÄS MER

5. 9. Early Cambrian Problematic Lophotrochozoans and Dilemmas of Scleritome Reconstructions

   Författare :Cecilia M Larsson; Lars E Holmer; Christian B Skovsted; Anette E S Högström; John S Peel; Glenn A Brock; Michael J Vendrasco; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Problematica; scleritome; Trachyplax; tommotiid; Cambrian; South Australia; North Greenland; Earth Science with specialization in Historical Geology and Palaeontology; Geovetenskap med inriktning mot historisk geologi och paleontologi;

   Sammanfattning : The emergence and radiation of metazoan body plans around the Precambrian/Cambrian boundary, some 500-600 million years ago, seems to be concordant with the appearance and diversification of preservable hard parts. Several Precambrian soft-bodied, multicellular organisms most likely represent stem-group bilaterians, but their fossil record is rather sparse. LÄS MER

7. 10. Isotope-based constraints on sources and processing of black carbon, carbon monoxide, and brown carbon in South Asia

   Författare :Sanjeev Dasari; Örjan Gustafsson; August Andersson; Jos Lelieveld; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; South Asia; Air Pollution; Short-Lived Pollutants; Atmospheric Abundance; Model-Observation Mismatch; Radiocarbon; Stable Isotopes; Applied Environmental Science; tillämpad miljövetenskap;

   Sammanfattning : The highly populated South Asian region is facing rapid economic growth and urbanization. Here, both climate- and health-affecting atmospheric agents such as light-absorbing aerosols black carbon (BC) and brown carbon (BrC), trace gas carbon monoxide (CO), are often found in relatively high levels compared to in other regions. LÄS MER