Stable-Isotope Geochemistry
Polygon mire in Arctic Siberia
Investigation of an ice wedge in Northern Siberia
The method of stable isotope analysis is an important proxy in palaeoclimate reconstructions. The stable water isotopes (∂18O and ∂D) in precipitation are the basis for the reconstruction of palaeotemperatures due to the empirical linear relationship between mean annual air temperature and the mean isotopic composition of precipitation. They are used to reconstruct climate variations of both hemispheres using different archives such as glacier ice and ground ice (e. g. ice wedges).
Stable isotope research at AWI Potsdam is mainly carried out for the periglacial permafrost areas of eastern Siberia (e. g. the Lena River delta, the Bykovsky Peninsula, the Verkhoyansk Mountains and the New Siberian Islands) as well as for bipolar glaciological studies (in Dronning Maud Land in Antarctica as well as for the Severnaya Semlya Ice Cap in the Russian Arctic).
Ground ice is defined as all types of ice in freezing or frozen ground. Different types of ground ice (e. g. segregated ice, ice wedges, pingo ice) are formed by different cryogenic processes and fed by different types of meteoric water. Stable isotopes help to distinguish between types of ice of different geneses. Additionally, stable oxygen and hydrogen isotopes are used as tracers for ground ice formation processes and for different source regions and pathways of atmospheric precipitation. They also reflect local factors such as air temperature and continentality.
d18O and dD, recovered from glacier ice of the Arctic (Severnaya Semlya) and Antarctica (EPICA Dronning Maud Land), is being used to construct a high-detail paleoclimate record for the Holocene (in the case of the Severnaya Semlya glacier) and much beyond (The Antarctic Dronning Maud Land ice core record exceeds 150000 years). The ratio of 18O/16O varies in approximate proportion to the temperature at the time the original precipitation occured.
Stable nitrogen and carbon isotopes are well-known proxies for ecological studies. At AWI Potsdam, these isotopes are mostly applied to organic material in soils and sediments for the reconstruction of paleoenvironmental conditions especially in the Siberian permafrost areas. Additionally, carbonate oxygen and carbon isotopes are analysed.
International Networking: Working Group on Isotopes and Geochemistry of Permafrost
