Sökning: "sediment core"

Visar resultat 6 - 10 av 49 avhandlingar innehållade orden sediment core.

1. 6. Determination of some polybrominated flame retardants in biota, sediment and sewage sludge

   Författare :Ulla Sellström; Janneche Utne Skaare; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Environmental Chemistry; miljökemi;

   Sammanfattning : Brominated flame retardants (BFRs) are mainly used in different polymers, and can be released to the environment during industrial processes, during the entire life-time of the flame-retarded product and after disposal. The aim of the present study was to gain knowledge about occurrence and concentrations of some BFRs in the environment, to search for sources for these chemicals and to investigate changes in concentrations over time. LÄS MER

3. 7. The sensitivity of Swedish alpine lakes to hydro-climatic changes during the Late Holocene

   Författare :Annika Berntsson; Gunhild Rosqvist; Peter G. Langdon; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; alpine lake sediments; temperature reconstruction; precipitation; catchment erosion; chironomids; oxygen isotopes; XRF core scanning; geomorphology; grain size analysis; kvartärgeologi; Quaternary Geology;

   Sammanfattning : The thesis objective is to use lake sediments to investigate the relationships between chironomids, as proxy for temperature, and δ18O and minerogenic in-wash, as precipitation proxies, in northern Sweden during the Late Holocene. Three lakes along a N–S transect in the Scandes were studied using biological, geochemical and physical sediment properties, together with numerical methods. LÄS MER

4. 8. Event stratigraphy for the Last Glacial-Holocene transition in eastern middle Sweden

   Författare :Jonas Björck; Michael J.C Walker; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Last Glacial-Holocene transition; event stratigraphy; eastern middle Sweden; pollen; plant macrofossils; marine calcareous fossils; microtephra; radiocarbon dating; clay varve chronology; GRIP; ice-core chronology; calendar year chronology; Preboreal oscillation; Yoldia Sea; Baltic Ice Lake; Quaternary Geology; kvartärgeologi;

   Sammanfattning : This thesis outlines an event stratigraphy for the Last Glacial-Holocene transition in eastern middle Sweden. Events are short-lived occurrences that have left traces in the geological record and which, therefore, may be used for correlation and inter-regional comparisons. LÄS MER

5. 9. Varved lake sediments and diagenetic processes

   Författare :Veronika Gälman; Ingemar Renberg; Daniel Conley; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Varved annually laminated lake sediment; diagenesis; varve appearance; iron; sulfur; chemical speciation; iron cycling; carbon; nitrogen; stabile isotopes; δ13C; δ15N; Earth sciences; Geovetenskap;

   Sammanfattning : Varved (annually laminated) sediments are of great interest for inference of past environmental conditions, as they provide dated records with high time resolution. After deposition, the sediment varves are affected by diagenesis; i.e., chemical, physical and biological changes that occur within the sediment. LÄS MER

7. 10. Paleolimnological reconstructions of fish population changes in acidified lakes

   Författare :Fredrik Palm; Göteborgs universitet; []
   Nyckelord :Acidification; Chaoborus; C. flavicans; C. obscuripes; Cyprinids; Daphnia; Fish loss; Fish community composition; Ephippia; Fragmentation; Mandibles; Perch; Roach; Sediments; 210-Pb chronology;

   Sammanfattning : This thesis deals with the potential of using subfossil Chaoborus spp. and Daphnia spp. remains preserved in lake sediments to reveal past fish community alterations related to progressive acidification. LÄS MER