Colored dissolved organic matter in thermokarst lakes of Yamal peninsula: sources, annual variations and connection to lake and catchment properties

• Main Authors: Dvornikov, Yury, Leibman, Marina, Heim, Birgit, Bartsch, Annett, Herzschuh, Ulrike, Khomutov, Artem, Widhalm, Barbara, Skorospekhova, Tatyana, Mikhaylova, Maria
• Format: Conference Object
• Language: unknown
• Published: 2016
• Subjects: Arctic; Yamal Peninsula; permafrost; Thermokarst; Siberia
• Online Access: https://epic.awi.de/id/eprint/41222/; http://icop2016.org/index.php/program/scientific-program; https://hdl.handle.net/10013/epic.48155

Ongoing Arctic warming changes arctic landscapes in various ways. It potentially alters the organic matter supply to lakes in the Arctic. Arctic warming may increase vegetation density in the catchments of lakes and thus increase of the organic matter supply to the lakes can be expected. Furthermore, warming may cause an increase of ground temperature and deepening of the active layer in permafrost soils, and thus activate various cryogenic processes including thermodenudation (Leibman et al. 2015). We present results of study of colored dissolved organic matter (CDOM) in thermokarst lakes of the central Yamal peninsula (Western Siberia, Russia) and the interconnection of CDOM with lake and catchment characteristics. We used a complex approach including field observations, laboratory measurements, and high spatial resolution optical and synthetic aperture radar (SAR) remote sensing and geographical information system (GIS) data analysis. CDOM absorption and spectral slope values, and suspended particulate matter concentrations (SPM) in several thermokarst lakes were obtained during 2011 – 2015 field campaigns. Availability of very high spatial resolution (GeoEye-1, WorldView-2) and high spatial resolution (SPOT5) optical satellite images as well as high resolution TanDEM-X DEM data, TSX and ALOS PALSAR SAR satellite images for the study area allowed to produce a large dataset of lake and catchment-related parameters (n=18). CDOM absorption at 440 nm in 363 lakes was retrieved from optical satellite images (correlation with in-situ data: R^2=0.68, n=24) using the band ratio method of Kutser et al. (2005). We also detected that increased turbidity in some of the lakes due to wind events in some of the optical satellite acquisitions affect the accuracy of retrieved CDOM values. The statistical analysis “boosted regression tree” was applied in order to find the most important variables controlling the CDOM concentration in central Yamal thermokarst lakes. The results show the following most important variables: the ...