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Microbial production of nitrous oxide and nitric oxide in boreal peatlands

Abstract

Soils are an important source of nitrous oxide (N{sub 2}O) and nitric oxide (NO). N{sub 2}O is a greenhouse gas participating in both warming of the climate and the destruction of ozone, and NO is active in tropospheric chemistry. The fluxes and formation mechanisms of these gases in boreal Finnish peatlands were studied by both laboratory and field techniques. Special attention was paid to factors regulating their production, e.g. height of the water table, pH, temperature, nutrient level and nitrification activity. Both N{sub 2}O and NO fluxes were detected in the peatlands, some of which were sources of these trace gases and some sinks. The flux rates of N{sub 2}O ranged from negative values to several milligrammes per square metre per day. Natural peatlands were the lowest sources of N{sub 2}O, often showing negative fluxes, whereas sites drained for forestry some decades ago had markedly higher fluxes. A site drained for agriculture (grassland) was the highest source found. NO fluxes were observed on the two drained sites studied, a forested fen and the same field of grass, but not on a natural fen with a high water table. NO fluxes amounted to 16-30 % of the N{sub 2}O flux rates.  More>>
Authors:
Publication Date:
Dec 31, 1998
Product Type:
Thesis/Dissertation
Report Number:
JOY-LT-50
Reference Number:
SCA: 010900; 540320; PA: FI-99:003349; EDB-99:077348; SN: 99002121462
Resource Relation:
Other Information: TH: Thesis (Ph.D.); PBD: 1998
Subject:
01 COAL, LIGNITE, AND PEAT; 54 ENVIRONMENTAL SCIENCES; BOREAL REGIONS; EMISSION; NITRIC OXIDE; NITROUS OXIDE; PEAT; PRODUCTION; WATER TABLES; WETLANDS; FINLAND; DENITRIFICATION; NUTRIENTS; 010900; 540320; ENVIRONMENTAL ASPECTS; CHEMICALS MONITORING AND TRANSPORT
OSTI ID:
10147825
Research Organizations:
Joensuu Univ. (Finland). Faculty of Science
Country of Origin:
Finland
Language:
English
Other Identifying Numbers:
Other: ON: DE99758878; ISBN 951-708-725-X; TRN: FI9903349
Availability:
OSTI; NTIS; INIS
Submitting Site:
FI
Size:
209 p.
Announcement Date:
Sep 13, 1999

Citation Formats

Regina, K. Microbial production of nitrous oxide and nitric oxide in boreal peatlands. Finland: N. p., 1998. Web.
Regina, K. Microbial production of nitrous oxide and nitric oxide in boreal peatlands. Finland.
Regina, K. 1998. "Microbial production of nitrous oxide and nitric oxide in boreal peatlands." Finland.
@misc{etde_10147825,
title = {Microbial production of nitrous oxide and nitric oxide in boreal peatlands}
author = {Regina, K}
abstractNote = {Soils are an important source of nitrous oxide (N{sub 2}O) and nitric oxide (NO). N{sub 2}O is a greenhouse gas participating in both warming of the climate and the destruction of ozone, and NO is active in tropospheric chemistry. The fluxes and formation mechanisms of these gases in boreal Finnish peatlands were studied by both laboratory and field techniques. Special attention was paid to factors regulating their production, e.g. height of the water table, pH, temperature, nutrient level and nitrification activity. Both N{sub 2}O and NO fluxes were detected in the peatlands, some of which were sources of these trace gases and some sinks. The flux rates of N{sub 2}O ranged from negative values to several milligrammes per square metre per day. Natural peatlands were the lowest sources of N{sub 2}O, often showing negative fluxes, whereas sites drained for forestry some decades ago had markedly higher fluxes. A site drained for agriculture (grassland) was the highest source found. NO fluxes were observed on the two drained sites studied, a forested fen and the same field of grass, but not on a natural fen with a high water table. NO fluxes amounted to 16-30 % of the N{sub 2}O flux rates. The importance of the water table in regulating N{sub 2}0 fluxes was demonstrated in field and laboratory studies. It was shown in the laboratory that even a short lowering of the water table, for 14 weeks at 20 deg C, induced N{sub 2}0 fluxes from the fens that normally acted as sinks or only low sources. Raising the water table in peat monoliths from drained sites reduced the flux of N{sub 2}O. Nutrient-rich peatlands had much higher capacities for N{sub 2}O and NO production than poorer ones. The addition of KNO{sub 3}, NH{sub 4}Cl or urea to minerotrophic peat further increased the fluxes of N{sub 2}O and NO, and also nitrogen mineralisation. There was a clear connection between the fluxes of N{sub 2}0 and NO and nitrification activity measured as the numbers of nitrite-oxidising bacteria, nitrification potential or in situ net nitrification. Nitrite oxidisers were much more numerous than ammonium oxidisers in the peaty soils, which indicates either better survival ability of nitrite oxidisers or shortcomings in the medium for ammonium oxidisers. The in situ nitrification rate in a boreal forested peatland was similar to or higher than those recorded for temperate and boreal forest soils receiving a high nitrogen input from the atmosphere. N{sub 2}O and NO emissions were 5.8 % and 0.6 % of the nitrification rates in situ, respectively. Both nitrification and denitrification participated in trace gas production in samples from a drained, forested fen. Nitrification predominated in the upper peat layer (0-5 cm), whereas denitrification was the most probable source of N{sub 2}0 deeper in the profile. Both vertical and spatial variation in the source of N{sub 2}O was observed The litter layer was a significant source of NO, producing as much as 75 % of that emitted from the peat profile. Nitrification was a minor source of N{sub 2}O and NO in the litter layer. The results show that boreal peatlands, which are vast reservoirs of nitrogen, are potential sources of N{sub 2}O and NO, especially if their naturally high water table is lowered by human activities or climatic warming. (orig.)}
place = {Finland}
year = {1998}
month = {Dec}
}