Isotope composition of dissolved organic carbon in runoff and peat leachates from a Central European wetland: Temporal and spatial variability in DOC sources

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F19%3A00000038" target="_blank" >RIV/00025798:_____/19:00000038 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/pii/S0341816218304387?dgcid=coauthor" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0341816218304387?dgcid=coauthor</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.catena.2018.10.011" target="_blank" >10.1016/j.catena.2018.10.011</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Isotope composition of dissolved organic carbon in runoff and peat leachates from a Central European wetland: Temporal and spatial variability in DOC sources

Popis výsledku v původním jazyce

In the near future, climate change will increasingly affect export of carbon (C) from peatlands. Terminal mineralization of dissolved organic carbon (DOC) is a source of greenhouse gases (carbon dioxide, CO2, and methane, CH4) for the atmosphere, and may contribute to climatic warming. Quantitative understanding of sources, dispersion pathways, and degradation of DOC produced in peat bogs is important for predictions of global change dynamics. Here we explore the potential of combining C isotope ratios of isotopically stratified, 210Pb-dated peat deposits and C isotope ratios of DOC exported via runoff to determine the depth and age of the predominant DOC source. In a poorly drained, Sphagnum-derived peat bog in the Czech Republic, delta13C values of bulk peat increased downcore to a depth of 10 cm. The C isotope signatures of fresh DOC and bulk peat differ only insignificantly, because C isotope changes in maturating peat require multiple microbial modifications of the organic matter taking place over relatively long time periods. Based on 41 samplings of runoff, 70 percent of exported DOC originated from peat substrate 1 to 10 years old, 2-10 cm deep. Recently photosynthesized DOC (< 1 year old) contributed about 5 percent to runoff DOC, whereas approximately 25 percent of exported DOC was derived from peat layers older than 10 years. Because biogenic methane at the study site contained isotopically extremely light C (delta13C values of -64.2 to -53.2 per mille), it would seem reasonable to expect residual DOC following partial decomposition to become isotopically heavier. A short-term laboratory incubation of wet peat samples from four depths at mid-summer temperatures indicated more complicated delta13C systematics. The initial limited amount of DOC in the leachate was isotopically heavy, compared to bulk peat, but after 18 days, delta13CDOC became lower, converging to the C isotope signature of bulk peat. Such delta13C systematics can be explained by multi-step isotope effects associated with different reaction rates during substrate decomposition. Limitations of using the combination of within-bog delta13C systematics and 210Pb dating of recent peat accretion are discussed. Horizontal heterogeneity in substrate C isotope signatures is one of the main sources of uncertainty of this approach to DOC source apportionment in peaty soils.

Název v anglickém jazyce

Isotope composition of dissolved organic carbon in runoff and peat leachates from a Central European wetland: Temporal and spatial variability in DOC sources

Popis výsledku anglicky

In the near future, climate change will increasingly affect export of carbon (C) from peatlands. Terminal mineralization of dissolved organic carbon (DOC) is a source of greenhouse gases (carbon dioxide, CO2, and methane, CH4) for the atmosphere, and may contribute to climatic warming. Quantitative understanding of sources, dispersion pathways, and degradation of DOC produced in peat bogs is important for predictions of global change dynamics. Here we explore the potential of combining C isotope ratios of isotopically stratified, 210Pb-dated peat deposits and C isotope ratios of DOC exported via runoff to determine the depth and age of the predominant DOC source. In a poorly drained, Sphagnum-derived peat bog in the Czech Republic, delta13C values of bulk peat increased downcore to a depth of 10 cm. The C isotope signatures of fresh DOC and bulk peat differ only insignificantly, because C isotope changes in maturating peat require multiple microbial modifications of the organic matter taking place over relatively long time periods. Based on 41 samplings of runoff, 70 percent of exported DOC originated from peat substrate 1 to 10 years old, 2-10 cm deep. Recently photosynthesized DOC (< 1 year old) contributed about 5 percent to runoff DOC, whereas approximately 25 percent of exported DOC was derived from peat layers older than 10 years. Because biogenic methane at the study site contained isotopically extremely light C (delta13C values of -64.2 to -53.2 per mille), it would seem reasonable to expect residual DOC following partial decomposition to become isotopically heavier. A short-term laboratory incubation of wet peat samples from four depths at mid-summer temperatures indicated more complicated delta13C systematics. The initial limited amount of DOC in the leachate was isotopically heavy, compared to bulk peat, but after 18 days, delta13CDOC became lower, converging to the C isotope signature of bulk peat. Such delta13C systematics can be explained by multi-step isotope effects associated with different reaction rates during substrate decomposition. Limitations of using the combination of within-bog delta13C systematics and 210Pb dating of recent peat accretion are discussed. Horizontal heterogeneity in substrate C isotope signatures is one of the main sources of uncertainty of this approach to DOC source apportionment in peaty soils.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10618 - Ecology

Projekt

<a href="/cs/project/GA16-18079S" target="_blank" >GA16-18079S: Izotopové doklady mikrobiální fixace dusíku v ombrotrofních mokřadech</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Catena

ISSN

0341-8162

e-ISSN

—

Svazek periodika

173

Číslo periodika v rámci svazku

February

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

9

Strana od-do

217-225

Kód UT WoS článku

000452814300021

EID výsledku v databázi Scopus

2-s2.0-85054912538