15N tracers and microbial analyses reveal in situ N2O sources in contrasting water regimes of a drained peatland forest

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外文摘要：Managed peatlands are a significant source of nitrous oxide(N2O),a powerful greenhouse gas and stratospheric ozone depleter.Due to the complexity and diversity of microbial N2O processes,different methods such as tracer,isotopomer,and microbiological technologies are required to understand these processes.The combined application of different methods helps to precisely estimate these processes,which is crucial for the future management of drained peatlands,and to mitigate soil degradation and negative atmospheric impact.In this study,we investigated N2O sources by combining tracer,isotopomer,and microbial analysis in a drained peatland forest under flooded and drained treatments.On average,the nitrification genes showed higher abundances in the drained treatment,and the denitrification genes showed higher abundances in the flooded treatment.This is consistent with the underlying chemistry,as nitrification requires oxygen while denitrification is anaerobic.We observed significant differences in labelled N2O fluxes between the drained and flooded treatments.The emissions of N2O from the flooded treatment were nearly negligible,whereas the N2O evolved from the nitrogen-15(15N)-labelled ammonium(15NH4+)in the drained treatment peaked at 147 pg 15N m-2 h-1.This initially suggested nitrification as the driving mechanism behind N2O fluxes in drained peatlands,but based on the genetic data,isotopic analysis,and N2O mass enrichment,we conclude that hybrid N2O formation involving ammonia oxidation was the main source of N2O emissions in the drained treatment.Based on the 15N-labelled nitrate(15NO3-)tracer addition and gene copy numbers,the low N2O emissions in the flooded treatment came possibly from complete denitrification producing inert dinitrogen.At atomic level,we observed selective enrichment of mass 45 of N2O molecule under 15NH4+amendment in the drained treatment and enrichment of both masses 45 and 46 under 15NO3-amendment in the flooded treatment.The selective enrichment of mass 45 in the drained treatment indicated the presence of hybrid N2O formation,which was also supported by the high abundances of archaeal genes.

外文关键词：

denitrificationnitrificationN2Oquantitative polymerase chain reaction

作者：

Mohit MASTA、Mikk ESPENBERG、Laura KUUSEMETS、Jaan P?RN、Sandeep THAYAMKOTTU、Holar SEPP、Kalle KIRSIM?E、Fotis SGOURIDIS、Kuno KASAK、Kaido SOOSAAR、ülo MANDER

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作者单位：

Institute of Ecology and Earth Sciences,University of Tartu,Vanemuise Street 46,Tartu 51003(Estonia)

School of Geographical Sciences,University of Bristol,University Road,Bristol BS81SS(UK)

基金：

Ministry of Education and Science of EstoniaEstonian Research CouncilEstonian Research CouncilEstonian Research CouncilEuropean Union through the European Regional Development Fund(Estonian EcolChange Centre of Excellence,Estonia)Mobilitas Pluss programmeEuropean Social Fund(Doctoral School of Earth Sciences and Ecology)

项目编号：

SF0180127s08IUT2-16PRG-352MOBERC20MOBTP101

出版年：

2024

DOI：

10.1016/j.pedsph.2023.06.006

土壤圈(英文版)

中国土壤学会,中科院南京土壤研究所和土壤与农业可持续发展国家重点实验室

土壤圈(英文版)

CSTPCD

影响因子：0.477

ISSN：1002-0160

年,卷(期)：2024.34(4)