Dissolved organic matter in the Lena River Delta Region, Siberia, Russia

• Main Authors: Gonçalves-Araujo, Rafael, Stedmon, Colin A, Heim, Birgit, Dubinenkov, Ivan, Kraberg, Alexandra Claudia, Moiseev, Denis, Bracher, Astrid
• Format: Dataset
• Language: English
• Published: PANGAEA 2015
• Subjects: Absorption coefficient; 350 nm; 443 nm; AWI Arctic Land Expedition; Biological index; Date/Time of event; DEPTH; water; Elevation of event; Event label; Fluorescence index; Fluorescence intensity; maximum; DOM; Humification index; Laptev Sea; Latitude of event; Lena2013; Longitude of event; MULT; Multiple investigations; Ratio; RU-Land_2013_Lena; Salinity; Specific ultraviolet absorbance normalized to DOC; Spectral slope of colored dissolved organic matter absorption; T1-1301; T1-1302; T1-1303; T1-1304; T1-1305; T1-1306; T1-1307; T1-3X-1; T4-1301; T4-1303; T4-1304; T4-1305; T5-1301; T5-1303; T5-1304; T6-1301; T6-1302; T6-1303; Temperature; Arctic; Climate change; laptev; lena delta; lena river; Siberia
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.844928; https://doi.org/10.1594/PANGAEA.844928

Connectivity between the terrestrial and marine environment in the Artic is changing as a result of climate change, influencing both freshwater budgets and the supply of carbon to the sea. This study characterizes the optical properties of dissolved organic matter (DOM) within the Lena Delta region and evaluates the behavior of DOM across the fresh water-marine gradient. Six fluorescent components (four humic-like; one marine humic-like; one protein-like) were identified by Parallel Factor Analysis (PARAFAC) with a clear dominance of allochthonous humic-like signals. Colored DOM (CDOM) and dissolved organic carbon (DOC) were highly correlated and had their distribution coupled with hydrographical conditions. Higher DOM concentration and degree of humification were associated with the low salinity waters of the Lena River. Values decreased towards the higher salinity Laptev Sea shelf waters. Results demonstrate different responses of DOM mixing in relation to the vertical structure of the water column, as reflecting the hydrographical dynamics in the region. Two mixing curves for DOM were apparent. In surface waters above the pycnocline there was a sharper decrease in DOM concentration in relation to salinity indicating removal. In the bottom water layer the DOM decrease within salinity was less. We propose there is a removal of DOM occurring primarily at the surface layer, which is likely driven by photodegradation and flocculation.