Sökning: "δ15N"

Visar resultat 6 - 10 av 20 avhandlingar innehållade ordet δ15N.

  1. 6. Towards understanding stable isotope signatures in stressed systems

    Författare :Caroline Ek; Elena Gorokhova; Katrine Borgå; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Stable isotope analysis; trophic position; chemical exposure; oxidative stress; Daphnia magna; Gammarus spp.; Limecola balthica; Applied Environmental Science; tillämpad miljövetenskap;

    Sammanfattning : Stable isotope analysis (SIA) is a valuable tool in ecotoxicology because δ13C and δ15N may provide insights into the trophic transfer of contaminants in a food web. The relationship between a species’ trophic position (TP, determined from δ15N) and internal concentration of biomagnifying contaminants can be established and used for regulatory purposes. LÄS MER

  3. 7. Biogeochemical evidences of human intervention in a shallow lake, Zeekoevlei, South Africa

    Författare :Supriyo Das; Joyanto Routh; Michael R. Talbot; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; lake; primary productivity; biomarkers; stable isotopes; trace elements; phosphorus; Earth sciences; Geovetenskap; geokemi; Geochemistry;

    Sammanfattning : This thesis describes a multi-parameter biogeochemical investigation in a shallow hyper-eutrophic freshwater coastal lake, Zeekoevlei, in South Africa. The predominance of autochthonous algal-derived organic matter in lake sediments is indicated by low C/N, high H/C ratios and δ13Corganic values. LÄS MER

  4. 8. Effects of heavy metal contamination on carbon and nitrogen cycling : An ecological approach to assess risks to soil functions

    Författare :Ingrid Rijk; Alf Ekblad; Dan Berggren Kleja; Erik Karltun; Örebro universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; heavy metals; soil contamination; stable isotopes; N cycling microbial guilds; 13C; 15N; nitrification; denitrification; biochar; soil respiration; microbial activity; bioavailability;

    Sammanfattning : Soil contamination with heavy metals may disrupt soil microorganisms with important roles in carbon (C) and nitrogen (N) cycling. However, there is a lack of understanding on how microorganisms are affected in soil, which may lead to a mismatch when assessing risks of contaminants to field soils. LÄS MER

  5. 9. Environmental and climatic changes in the Baltic Sea and the eastern Mediterranean Sea : as recorded by pigments and isotopes in sediments

    Författare :Johanna Borgendahl; Rolf Hallberg; Joyanto Routh; Stefano Bernasconi; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Earth sciences; Geovetenskap;

    Sammanfattning : This thesis is a study of Holocene sapropels from two semi-enclosed seas; the Baltic Sea and the Mediterranean Sea. Sapropels are sedimentary layers with organic C > 2%. LÄS MER

  7. 10. Studies of Baltic Sea plankton - spatial and temporal patterns

    Författare :Helena Höglander; Ulf Larsson; Christoph Humborg; Anna-Stiina Heiskanen; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Phytoplankton; Vertical distribution; Sedimentation; Baltic Sea; Cyanobacteria; Stable istopes; Cercopagis pengoi; Zooplankton; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Sammanfattning : This thesis examines the spatial and temporal patterns of Baltic Sea phyto- and zooplankton. Studies of such patterns are important to gain a better understanding of the offshore nutrient dynamics of the Baltic Sea (Papers I and II) and how to manage eutrophication and invasive species in coastal areas (Papers III and IV). LÄS MER