Sökning: "Carbon cycling"

Visar resultat 11 - 15 av 179 avhandlingar innehållade orden Carbon cycling.

1. 11. Land-atmosphere interaction of a subarctic palsa mire

   Författare :Marcin Jackowicz-Korczynski; Institutionen för naturgeografi och ekosystemvetenskap; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; eddy covariance; chamber; methnaol; isoprene; nonmethane hydrocarbons; methane; carbon dioxide; carbon; mire; permafrost; subarctic; palsa; greenhouse gas;

   Sammanfattning : The main objective of this thesis was to quantitatively estimate the gaseous exchange of carbon dioxide (CO2) and methane (CH4) between a subarctic wetland ecosystem and the atmosphere. Additionally some initial estimates of the carbon input to the atmosphere of nonmethane hydrocarbons (NMHCs) were also obtained by combining different techniques in a joint setting. LÄS MER

3. 12. Gas Exchange over Aquatic Interfaces and its Importance for Greenhouse Gas Emission

   Författare :Jovana Kokic; Sebastian Sobek; Erik Sahlée; Marcus B. Wallin; Anne Ojala; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; gas exchange; lake; stream; lake sediment; headwaters; carbon dioxide; methane; greenhouse gas emission; carbon; turbulence; Biology with specialization in Limnology; Biologi med inriktning mot limnologi;

   Sammanfattning : Aquatic ecosystems play a substantial role in global cycling of carbon (C), despite covering only about 4% of the earth surface. They emit large amounts of greenhouse gases (GHG) to the atmosphere, comparable to the amount of C stored annually in terrestrial ecosystems. In addition, C can be buried in lake sediments. LÄS MER

4. 13. 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

5. 14. Quantifying the impact of winter warming on the Arctic carbon cycle

   Författare :Alexandra Pongrácz; BECC: Biodiversity and Ecosystem services in a Changing Climate; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Arctic; snow; permafrost; LPJ-GUESS; non-growing season; carbon cycling; LPJ-GUESS; Arctic; permafrost; snow; carbon cycling; non-growing season;

   Sammanfattning : The Arctic has undergone extreme changes during the last decades and is warming over twice the global average. There has been increasing interest in understanding how warming and changes in snow and rainfall will affect high-latitude ecosystems. LÄS MER

7. 15. Temporal and spatial variability of carbon cycling in a subarctic landscape

   Författare :Torbjörn Johansson; Institutionen för naturgeografi och ekosystemvetenskap; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geologi; physical geography; Geology; Växtekologi; Plant ecology; Permafrost; Herbivory; Subarctic; Aerial photography; Vegetation change; Carbon balance; fysisk geografi;

   Sammanfattning : This thesis deals with the carbon balance in a subarctic landscape at different temporal and spatial scales. Its focus is mainly on the peatland and mountain birch forest (Betula pubescens ssp. czerepanovii) ecosystems within the Abisko area in northernmost Sweden. This is an area with a temperature close to the 0 OC mean annual isotherm. LÄS MER