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Different boreal terrestrial DOC sources show different δ13C signatures: implications for tracing labile doc across the land-water interface

Hensgens, Geert LU ; Lechtenfeld, Oliver and Berggren, Martin LU (2018) ASLO Summer Meeting 2018
Abstract
The stable carbon isotope ratio (δ13C) is a key tool in tracing the source of carbon within and across ecosystems. In isotope mixing models dissolved organic carbon (DOC) from terrestrial sources is often assigned a fixed δ13C of roughly -28‰ to -27‰ in C3 plant-dominated areas. However, the claim of a uniform δ13C distribution for terrestrial DOC sources of different reactivity has seldom been tested. We leached DOC from 40 sources in the Fennoscandinavian boreal forest, including four decay stages of litter from five dominant species and three organic soil types. Additionally incubations were applied in combination with the Keeling plot method to resolve the δ13C of the labile DOC. The results show a clear split between litter derived... (More)
The stable carbon isotope ratio (δ13C) is a key tool in tracing the source of carbon within and across ecosystems. In isotope mixing models dissolved organic carbon (DOC) from terrestrial sources is often assigned a fixed δ13C of roughly -28‰ to -27‰ in C3 plant-dominated areas. However, the claim of a uniform δ13C distribution for terrestrial DOC sources of different reactivity has seldom been tested. We leached DOC from 40 sources in the Fennoscandinavian boreal forest, including four decay stages of litter from five dominant species and three organic soil types. Additionally incubations were applied in combination with the Keeling plot method to resolve the δ13C of the labile DOC. The results show a clear split between litter derived (~-32‰) and wetland soil derived DOC (~-26‰). Furthermore the labile subfraction of litter derived DOC was relatively deplete in 13C compared with bulk DOC while in wetland soils the labile pool has a relatively heavier 13C signature. As a result both sources show a labile pool comparable to the initial 13C values of ~-32‰ and ~-26‰ respectively, while the resistant pools of DOC show equal 13C values around ~-27.5‰. Chemical measurements of pre- and post-incubation DOC show clear differences between labile pools of DOC from different sources, indicative of different fractionation processes contributing to the differences seen in 13C values of the respective labile pools. These results suggest that the use of 13C mixing models might lead to misjudging the true amount of terrestrial derived - and in particularly labile - DOC within boreal aquatic systems. (Less)
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author
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organization
publishing date
type
Contribution to conference
publication status
published
subject
pages
1 pages
conference name
ASLO Summer Meeting 2018
conference location
Victoria, Canada
conference dates
2018-06-10 - 2018-06-15
project
An empirical framework for large-scale modeling of dissolved organic carbon fluxes across soils and water
language
English
LU publication?
yes
id
10d7dd93-ae67-480c-b7b1-61c02e7db6e5
date added to LUP
2018-07-05 16:32:12
date last changed
2020-08-27 18:13:22
@misc{10d7dd93-ae67-480c-b7b1-61c02e7db6e5,
  abstract     = {The stable carbon isotope ratio (δ13C) is a key tool in tracing the source of carbon within and across ecosystems. In isotope mixing models dissolved organic carbon (DOC) from terrestrial sources is often assigned a fixed δ13C of roughly -28‰ to -27‰ in C3 plant-dominated areas. However, the claim of a uniform δ13C distribution for terrestrial DOC sources of different reactivity has seldom been tested. We leached DOC from 40 sources in the Fennoscandinavian boreal forest, including four decay stages of litter from five dominant species and three organic soil types. Additionally incubations were applied in combination with the Keeling plot method to resolve the δ13C of the labile DOC. The results show a clear split between litter derived (~-32‰) and wetland soil derived DOC (~-26‰). Furthermore the labile subfraction of litter derived DOC was relatively deplete in 13C compared with bulk DOC while in wetland soils the labile pool has a relatively heavier 13C signature. As a result both sources show a labile pool comparable to the initial 13C values of ~-32‰ and ~-26‰ respectively, while the resistant pools of DOC show equal 13C values around ~-27.5‰. Chemical measurements of pre- and post-incubation DOC show clear differences between labile pools of DOC from different sources, indicative of different fractionation processes contributing to the differences seen in 13C values of the respective labile pools. These results suggest that the use of 13C mixing models might lead to misjudging the true amount of terrestrial derived - and in particularly labile - DOC within boreal aquatic systems.},
  author       = {Hensgens, Geert and Lechtenfeld, Oliver and Berggren, Martin},
  language     = {eng},
  title        = {Different boreal terrestrial DOC sources show different δ13C signatures: implications for tracing labile doc across the land-water interface},
  year         = {2018},
}