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A compound-specific n-alkane δ13C and δD approach for assessing source and delivery processes of terrestrial organic matter within a forested watershed in northern Japan

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Title: A compound-specific n-alkane δ13C and δD approach for assessing source and delivery processes of terrestrial organic matter within a forested watershed in northern Japan
Authors: Seki, Osamu Browse this author →KAKEN DB
Nakatsuka, Takeshi Browse this author
Shibata, Hideaki Browse this author
Kawamura, Kimitaka Browse this author
Keywords: stable carbon isotope
hydrogen isotope
n-alkane
riverine organic matter
Issue Date: 15-Jan-2010
Publisher: Elsevier Ltd.
Journal Title: Geochimica et Cosmochimica Acta
Volume: 74
Issue: 2
Start Page: 599
End Page: 613
Publisher DOI: 10.1016/j.gca.2009.10.025
Abstract: We measured molecular distributions and compound-specific hydrogen (δD) and stable carbon isotopic ratios (δ13C) of mid- and long-chain n-alkanes in forest soils, wetland peats and lake sediments within the Dorokawa watershed, Hokkaido, Japan, to better understand sources and processes associate with delivery of terrestrial organic matter into the lake sediments. δ13C values of odd carbon numbered C23-C33 n-alkanes ranged from -37.2 to -31.5 ‰, while δD values of these alkanes showed a large degree of variability that ranged from -244 to -180 ‰. Molecular distributions in combination with stable carbon isotopic compositions indicate a large contribution of C3 trees as the main source of n-alkanes in forested soils whereas n-alkanes in wetland soil are exclusively derived from marsh grass and/or moss. We found that the n-alkane δD values are much higher in forest soils than wetland peat. The higher δD values in forest samples could be explained by the enrichment of deuterium in leaf and soil waters due to increased evapotranspiration in the forest or differences in physiology of source plants between wetland and forest. A δ13C v.s. δD diagram of n-alkanes among forest, wetland and lake samples showed that C25-C31 n-alkanes deposited in lake sediments are mainly derived from tree leaves due to the preferential transport of the forest soil organic matter over the wetland or an increased contribution of atmospheric input of tree leaf wax in the offshore sites. This study demonstrates that compound-specific δD analysis provides a useful approach for better understanding source and transport of terrestrial biomarkers in a C3 plant-dominated catchment.
Type: article (author version)
URI: http://hdl.handle.net/2115/42575
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

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