Contrasting potential for biological N2 fixation at three polluted central European Sphagnum peat bogs: combining the 15N2-tracer and natural-abundance isotope approaches

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F23%3A10169036" target="_blank" >RIV/00025798:_____/23:10169036 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.5194/soil-9-623-2023" target="_blank" >https://doi.org/10.5194/soil-9-623-2023</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.5194/soil-9-623-2023" target="_blank" >10.5194/soil-9-623-2023</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Contrasting potential for biological N2 fixation at three polluted central European Sphagnum peat bogs: combining the 15N2-tracer and natural-abundance isotope approaches

Popis výsledku v původním jazyce

Availability of reactive nitrogen (Nr) is a key control on carbon (C) sequestration in wetlands. To complement the metabolic demands of Sphagnum in pristine rain-fed bogs, diazotrophs supply additional Nr via biological nitrogen fixation (BNF). As breaking the triple bond of atmospheric N2 is energy-intensive, it is reasonable to assume that increasing inputs of pollutant Nr will lead to BNF downregulation. However, recent studies have also documented measurable BNF rates in Sphagnum-dominated bogs in polluted regions, indicating the adaptation of N2 fixers to changing N deposition. Our aim was to quantify BNF in high-elevation peatlands located in industrialized central Europe. A 15N2-tracer experiment was combined with a natural-abundance N-isotope study at three Sphagnum-dominated peat bogs in the northern Czech Republic in an attempt to assess the roles of individual BNF drivers. High short-term BNF rates (8.2 +- 4.6 g N m2 d-1) were observed at Malé mechové jezírko, which receives TILDE OPERATOR+D91 17 kg Nr ha-1 yr-1. The remaining two peat bogs, whose recent atmospheric Nr inputs differed from Malé mechové jezírko by only 1-2 kg ha-1 yr-1 (Uhlirska and Brumist), showed zero BNF. The following parameters were investigated to elucidate the BNF difference: the NH4+-N / NO3 - N ratio, temperature, wetness, Sphagnum species, organic-N availability, possible P limitation, possible molybdenum (Mo) limitation, SO42- deposition, and pH. At Malé mechové jezírko and Uhlířská, the same moss species (S. girgensohnii) was used for the 15N2 experiment; therefore, the host identity could not explain the difference in BNF at these sites. Temperature and moisture were also identical in all incubations and could not explain the between-site differences in BNF. The N : P stoichiometry in peat and bog water indicated that Brumišta may have lacked BNF due to P limitation, whereas non-detectable BNF at Uhlířská may have been related to the 70-fold higher SO42- concentration in bog water. Across the sites, the mean natural-abundance I 15N values increased in the following order: atmospheric deposition (-5.3 +- 0.3 %o) &lt; Sphagnum (-4.3 +- 0.1 %o) &lt; bog water (-3.9 +- 0.4 %o) &lt; atmospheric N2 (0.0 %o). Only at Brumišta was N in Sphagnum significantly isotopically heavier than in atmospheric deposition, possibly indicating a longer-term BNF effect. Collectively, our data highlight spatial heterogeneity in BNF rates under high Nr inputs as well as the importance of environmental parameters other than atmospheric Nr pollution in regulating BNF.

Název v anglickém jazyce

Contrasting potential for biological N2 fixation at three polluted central European Sphagnum peat bogs: combining the 15N2-tracer and natural-abundance isotope approaches

Popis výsledku anglicky

Availability of reactive nitrogen (Nr) is a key control on carbon (C) sequestration in wetlands. To complement the metabolic demands of Sphagnum in pristine rain-fed bogs, diazotrophs supply additional Nr via biological nitrogen fixation (BNF). As breaking the triple bond of atmospheric N2 is energy-intensive, it is reasonable to assume that increasing inputs of pollutant Nr will lead to BNF downregulation. However, recent studies have also documented measurable BNF rates in Sphagnum-dominated bogs in polluted regions, indicating the adaptation of N2 fixers to changing N deposition. Our aim was to quantify BNF in high-elevation peatlands located in industrialized central Europe. A 15N2-tracer experiment was combined with a natural-abundance N-isotope study at three Sphagnum-dominated peat bogs in the northern Czech Republic in an attempt to assess the roles of individual BNF drivers. High short-term BNF rates (8.2 +- 4.6 g N m2 d-1) were observed at Malé mechové jezírko, which receives TILDE OPERATOR+D91 17 kg Nr ha-1 yr-1. The remaining two peat bogs, whose recent atmospheric Nr inputs differed from Malé mechové jezírko by only 1-2 kg ha-1 yr-1 (Uhlirska and Brumist), showed zero BNF. The following parameters were investigated to elucidate the BNF difference: the NH4+-N / NO3 - N ratio, temperature, wetness, Sphagnum species, organic-N availability, possible P limitation, possible molybdenum (Mo) limitation, SO42- deposition, and pH. At Malé mechové jezírko and Uhlířská, the same moss species (S. girgensohnii) was used for the 15N2 experiment; therefore, the host identity could not explain the difference in BNF at these sites. Temperature and moisture were also identical in all incubations and could not explain the between-site differences in BNF. The N : P stoichiometry in peat and bog water indicated that Brumišta may have lacked BNF due to P limitation, whereas non-detectable BNF at Uhlířská may have been related to the 70-fold higher SO42- concentration in bog water. Across the sites, the mean natural-abundance I 15N values increased in the following order: atmospheric deposition (-5.3 +- 0.3 %o) &lt; Sphagnum (-4.3 +- 0.1 %o) &lt; bog water (-3.9 +- 0.4 %o) &lt; atmospheric N2 (0.0 %o). Only at Brumišta was N in Sphagnum significantly isotopically heavier than in atmospheric deposition, possibly indicating a longer-term BNF effect. Collectively, our data highlight spatial heterogeneity in BNF rates under high Nr inputs as well as the importance of environmental parameters other than atmospheric Nr pollution in regulating BNF.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

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

Název periodika

SOIL

ISSN

2199-398X

e-ISSN

2199-398X

Svazek periodika

9

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

DE - Spolková republika Německo

Počet stran výsledku

18

Strana od-do

623-640

Kód UT WoS článku

001170599600001

EID výsledku v databázi Scopus

2-s2.0-85182993350