Sorption of dissolved organic matter by mineral soils of the Siberian forest tundra

Because of low net production in arctic and subarctic surface water, dissolved organic matter (DOM) discharged from terrestrial settings plays an important role for carbon and nitrogen dynamics in arctic aquatic systems. Sorption, typically controlling the export of DOM from soil, may be influenced...

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Bibliographic Details
Published in:Global change biology 2006-10, Vol.12 (10), p.1868-1877
Main Authors: KAWAHIGASHI, MASAYUKI, KAISER, KLAUS, RODIONOV, ANDREJ, GUGGENBERGER, GEORG
Format: Article
Language:English
Subjects:
active layer
Carbon
dissolved organic matter
Freshwater
hydrophilic organic carbon
hydrophobic organic carbon
iron oxide
Nitrogen
organic horizon
Permafrost
Siberia
Soil sciences
sorption
tundra
Water
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Summary:Because of low net production in arctic and subarctic surface water, dissolved organic matter (DOM) discharged from terrestrial settings plays an important role for carbon and nitrogen dynamics in arctic aquatic systems. Sorption, typically controlling the export of DOM from soil, may be influenced by the permafrost regime. To confirm the potential sorptive control on the release of DOM from permafrost soils in central northern Siberia, we examined the sorption of DOM by mineral soils of Gelisols and Inceptisols with varying depth of the active layer. Water-soluble organic matter in the O horizons of the Gelisols was less (338 and 407 mg C kg⁻¹) and comprised more dissolved organic carbon (DOC) in the hydrophobic fraction (HoDOC) (63% and 70%) than in the O horizons of the Inceptisols (686 and 706 mg C kg⁻¹, 45% and 48% HoDOC). All A and B horizons from Gelisols sorbed DOC strongly, with a preference for HoDOC. Almost all horizons of the Inceptisols showed a weaker sorption of DOC than those of the Gelisols. The C horizons of the Inceptisols, having a weak overall DOC sorption, sorbed C in the hydrophilic fraction (HiDOC) stronger than HoDOC. The reason for the poor overall sorption and also the preferential sorption of HiDOC is likely the high pH (pH>7.0) of the C horizons and the smaller concentrations of iron oxides. For all soils, the sorption of HoDOC related positively to oxalate- and dithionite-citrate-extractable iron. The A horizons released large amounts of DOC with 46-80% of HiDOC. The released DOC was significantly (r=0.78, P
ISSN:1354-1013
1365-2486
DOI:10.1111/j.1365-2486.2006.01203.x