Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils
Nitrous oxide (N 2 O) emissions from permafrost-affected terrestrial ecosystems have received little attention, largely because they have been thought to be negligible. Recent studies, however, have shown that there are habitats in subarctic tundra emitting N 2 O at high rates, such as bare peat sur...
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ftcopernicus:oai:publications.copernicus.org:bgd97126 2023-05-15T15:04:56+02:00 Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils Gil, Jenie A. Marushchak, Maija E. Rütting, Tobias Baggs, Elizabeth M. Pérez, Tibisay Novakovskiy, Alexander Trubnikova, Tatiana Kaverin, Dmitry Martikainen, Pertti J. Biasi, Christina 2021-08-26 application/pdf https://doi.org/10.5194/bg-2021-228 https://bg.copernicus.org/preprints/bg-2021-228/ eng eng doi:10.5194/bg-2021-228 https://bg.copernicus.org/preprints/bg-2021-228/ eISSN: 1726-4189 Text 2021 ftcopernicus https://doi.org/10.5194/bg-2021-228 2021-08-30T16:22:16Z Nitrous oxide (N 2 O) emissions from permafrost-affected terrestrial ecosystems have received little attention, largely because they have been thought to be negligible. Recent studies, however, have shown that there are habitats in subarctic tundra emitting N 2 O at high rates, such as bare peat surfaces on permafrost peatlands. The processes behind N 2 O production in these high-emitting habitats are, however, poorly understood. In this study, we established an in situ 15 N-labelling experiment with the main objectives to partition the microbial sources of N 2 O emitted from bare peat surfaces (BP) on permafrost peatlands and to study the fate of ammonium and nitrate in these soils and in adjacent vegetated peat surfaces (VP) showing low N 2 O emissions. Our results confirm the hypothesis that denitrification is mostly responsible for the high N 2 O emissions from BP surfaces. During the study period denitrification contributed with ~79 % of the total N 2 O emission in BP, while the contribution of ammonia oxidation was less, about 19 %. However, nitrification is a key process for the overall N 2 O production in these soils with negligible external nitrogen (N) load because it is responsible for nitrite/nitrate supply for denitrification, as also supported by relatively high gross nitrification rates in BP. Generally, both gross N mineralization and gross nitrification rates were much higher in BP with high N 2 O emissions than in VP, where the high C / N ratio together with low water content was likely limiting N mineralization and nitrification and, consequently, N 2 O production. Also, competition for mineral N between plants and microbes was additionally limiting N availability for N 2 O production in VP. Our results show that multiple factors control N 2 O production in permafrost peatlands, the absence of plants being a key factor together with inter-mediate to high water content and low C / N ratio, all factors which also impact on gross N turnover rates. The intermediate to high soil water content which creates anaerobic microsites in BP is a key N 2 O emission driver for the prevalence of denitrification to occur. This knowledge is important for evaluating future permafrost –N feedback loops from the Arctic. Text Arctic permafrost Subarctic Tundra Copernicus Publications: E-Journals Arctic |
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Copernicus Publications: E-Journals |
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English |
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Nitrous oxide (N 2 O) emissions from permafrost-affected terrestrial ecosystems have received little attention, largely because they have been thought to be negligible. Recent studies, however, have shown that there are habitats in subarctic tundra emitting N 2 O at high rates, such as bare peat surfaces on permafrost peatlands. The processes behind N 2 O production in these high-emitting habitats are, however, poorly understood. In this study, we established an in situ 15 N-labelling experiment with the main objectives to partition the microbial sources of N 2 O emitted from bare peat surfaces (BP) on permafrost peatlands and to study the fate of ammonium and nitrate in these soils and in adjacent vegetated peat surfaces (VP) showing low N 2 O emissions. Our results confirm the hypothesis that denitrification is mostly responsible for the high N 2 O emissions from BP surfaces. During the study period denitrification contributed with ~79 % of the total N 2 O emission in BP, while the contribution of ammonia oxidation was less, about 19 %. However, nitrification is a key process for the overall N 2 O production in these soils with negligible external nitrogen (N) load because it is responsible for nitrite/nitrate supply for denitrification, as also supported by relatively high gross nitrification rates in BP. Generally, both gross N mineralization and gross nitrification rates were much higher in BP with high N 2 O emissions than in VP, where the high C / N ratio together with low water content was likely limiting N mineralization and nitrification and, consequently, N 2 O production. Also, competition for mineral N between plants and microbes was additionally limiting N availability for N 2 O production in VP. Our results show that multiple factors control N 2 O production in permafrost peatlands, the absence of plants being a key factor together with inter-mediate to high water content and low C / N ratio, all factors which also impact on gross N turnover rates. The intermediate to high soil water content which creates anaerobic microsites in BP is a key N 2 O emission driver for the prevalence of denitrification to occur. This knowledge is important for evaluating future permafrost –N feedback loops from the Arctic. |
format |
Text |
author |
Gil, Jenie A. Marushchak, Maija E. Rütting, Tobias Baggs, Elizabeth M. Pérez, Tibisay Novakovskiy, Alexander Trubnikova, Tatiana Kaverin, Dmitry Martikainen, Pertti J. Biasi, Christina |
spellingShingle |
Gil, Jenie A. Marushchak, Maija E. Rütting, Tobias Baggs, Elizabeth M. Pérez, Tibisay Novakovskiy, Alexander Trubnikova, Tatiana Kaverin, Dmitry Martikainen, Pertti J. Biasi, Christina Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils |
author_facet |
Gil, Jenie A. Marushchak, Maija E. Rütting, Tobias Baggs, Elizabeth M. Pérez, Tibisay Novakovskiy, Alexander Trubnikova, Tatiana Kaverin, Dmitry Martikainen, Pertti J. Biasi, Christina |
author_sort |
Gil, Jenie A. |
title |
Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils |
title_short |
Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils |
title_full |
Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils |
title_fullStr |
Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils |
title_full_unstemmed |
Sources of nitrous oxide and fate of mineral nitrogen in sub-Arctic permafrost peat soils |
title_sort |
sources of nitrous oxide and fate of mineral nitrogen in sub-arctic permafrost peat soils |
publishDate |
2021 |
url |
https://doi.org/10.5194/bg-2021-228 https://bg.copernicus.org/preprints/bg-2021-228/ |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic permafrost Subarctic Tundra |
genre_facet |
Arctic permafrost Subarctic Tundra |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bg-2021-228 https://bg.copernicus.org/preprints/bg-2021-228/ |
op_doi |
https://doi.org/10.5194/bg-2021-228 |
_version_ |
1766336680969633792 |