Artikkelit jotka sisältää sanan 'methane'
Metsäojituksen vaikutuksesta ilmastoon.
English title: Climatic impacts of forestry on drained boreal peatlands.
Original keywords:
turvemaa;
ojitus;
hiilidioksidi;
metaani;
kasvihuonekaasut;
typpioksiduuli;
suometsätalous
English keywords:
peat;
peatland forestry;
ditching;
Carbon dioxide;
methane;
nitrous oxide;
greenhouse gases
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Metsäojitus vähentää merkittävästi soiden metaanipäästöjä. Rehevien ruoho- ja mustikkaturvekankaiden maaperä on kuitenkin merkittävä hiilidioksidin lähde ilmakehään turpeen vähenemisen takia. Karujen puolukka- ja varputurvekankaiden turve ei näyttäisi nykyisin merkittävästi vähenevän. Puustobiomassan merkittävän suurenemisen ansiosta Suomen metsäojitetut suot ovat tällä hetkellä kasvihuonekaasujen nettonielu.
Ilmastonmuutoksen hillitsemisen kannalta metsänkasvatuksen jatkaminen lienee paras maankäyttömuoto metsäojitetuille soille lähivuosikymmenten aikana. Vaikka laajamittaisella ennallistamisella voitaisiin estää rehevien soiden turpeen väheneminen, samalla kuitenkin puuston kasvu vähenisi ja metaanipäästö kasvaisi. Ennallistamisen jälkeen kestänee vähintään kymmeniä tai satoja vuosia, ennen kuin saavutetaan ilmaston kannalta metsänkasvatuksen jatkamista parempi tilanne. Pitkällä aikavälillä rehevien soiden ennallistaminen on kuitenkin ilmaston kannalta parempi vaihtoehto, koska jo muutaman kymmenen senttimetrin paksuisen turvekerroksen häviäminen vapauttaa enemmän hiiltä ilmakehään kuin kookaskaan puusto pystyy sitomaan itseensä.
Metsäojitettujen soiden kasvihuonekaasutaseista on viime vuosina kertynyt melko kattavasti tietoa. Jotta metsätalouden jatkamisen tai mahdollisen puuston kasvamaan jättämisen tai suon ennallistamisen ilmastovaikutuksen suuruutta voidaan täsmällisesti arvioida, tarvitaan vertailulaskelmia eri vaihtoehtojen kasvihuonekaasupäästöistä. Suuren kokonaispinta-alan takia metsäojitettujen soiden tulevalla käytöllä voi olla suuri vaikutus Suomen kasvihuonekaasupäästöihin.
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Ojanen,
Luonnonvarakeskus (LUKE)
Sähköposti:
paavo.ojanen@helsinki.fi
Talviaikainen hiilivuo boreaaliselta suosukkessiogradientilta seuraa kesäaikaisen hiilidynamiikan vaihtelua.
English title: Winter carbon losses from a boreal mire succession sequence follow summertime patterns in carbon dynamics.
Original keywords:
sukkessio;
suon kehitys;
primaarisoistuminen;
hiilidioksidi;
metaani;
lumikerros;
Siikajoki;
maankohoamisrannikko
English keywords:
Carbon dioxide;
methane;
Mire development;
land uplift coast;
mire succession;
primary paludification;
snow pack;
Siikajoki
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Although carbon (C) gas exchange during the summer largely determines the annual C balance of mires, the wintertime fluxes cannot be ignored. Decomposition continues as long as the soil is not frozen and a proportion of the gases produced during summer are also released during winter. We measured carbon dioxide (CO2) and methane (CH4) fluxes along a successional mire sequence during two winters following growing seasons with divergent weather conditions. We studied the successional trends in wintertime C release in boreal mires, and quantified the contribution of wintertime C fluxes to annual fluxes. Wintertime CO2 and CH4 fluxes from the successional mire sequence were related to the flux rates during the previous summer. Average winter CO2 release along the successional sequence varied between 19.5 and 44.9 g CO2-C m–2 winter–1(6-months), and accounted for 8–14% of the annual CO2 release. There was no clear successional trend in CO2 fluxes. Average winter CH4 release along the successional sequence varied between 0.20 and 7.29 CH4-C g m–2 winter–1(6-months).The winter CH4 fluxes accounted for up to 38% of the annual CH4 emissions. Occasional CH4 uptake was detected at the younger successional stages during winter following the dry summer, while after the wet summer all sites emitted CH4. In general, most of the winter C losses were composed of CO2.
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Leppälä,
Mirva Leppälä, Finnish Forest Research Institute, FIN-91500 Muhos, Finland. Current address: Metsähallitus, Natural Heritage Services Ostrobothnia, BOX 81, FI-90101 Oulu, Finland, email: mirva.leppala@metsa.fi
Sähköposti:
ei.tietoa@nn.oo
- Laine, Sähköposti: ei.tietoa@nn.oo
- Tuittila, Sähköposti: ei.tietoa@nn.oo
Vedenpinnan muutoksen lyhytaikaiset vaikutukset hiilidioksidi- ja metaanipäästöihin peittosuolla.
English title: The short-term effect of altered water level on carbon dioxide and methane fluxes in a blanket bog.
Avainsanat:
Sphagnum;
Drainage;
peatland;
methane;
flooding;
ecohydrology;
photosynthesis;
respiration;
Racomitrium;
Rhynchospora alba
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Peatlands play an important role in the global carbon (C) cycle, by acting as a large, long-term C sink. The C sink is sustained by a high water level that inhibits decomposition of organic matter. The C gas dynamics are therefore sensitive to changes in water level, and in climatically different years a peatland can vary from a sink to a source of C. We measured carbon dioxide (CO2) and methane (CH4) fluxes from vegetation communities ranging from hummocks to low lawns in a blanket bog. After a one-year calibration period the water level was both lowered and raised experimentally and the changes in vegetation composition and gas fluxes were monitored during a further year. In all vegetation communities the water level drawdown increased the respiration rate and decreased methane emission; rising water level decreased respiration and increased methane emissions. The effect of altered water level on photosynthesis depended on species composition. Water level drawdown decreased photosynthesis in most communities; rising water level decreased the photosynthesis of hummocks species, and increased the photosynthesis of Rhynchospora alba.
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Laine,
Anna M. Laine, Department of Civil and Environmental Engineering, University College Cork, Cork, Ireland; University of Oulu, Oulu, Finland, P.O. Box 3000, 90014 University of Oulu, telephone: +358 8 5531521, email: anna.laine@oulu.fi
Sähköposti:
ei.tietoa@nn.oo
- Byrne, Sähköposti: ei.tietoa@nn.oo
- Kiely, Sähköposti: ei.tietoa@nn.oo
- Tuittila, Sähköposti: ei.tietoa@nn.oo
Micrometeorological measurements of methane and energy fluxes in a Minnesota peatland.
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The micrometeorological eddy correlation technique was used to measure fluxes of methane and energy. Results from these measurements made in a Minnesota peatland are reviewed here. The field observations made in a pilot study (1990) demonstrated the utility of the eddy correlation technique for measuring surface fluxes of methane. Seasonal distribution of methane flux at the same site was obtained in a detailed study (May to October) in 1991. The evapotranspiration rates and other components of the surface energy budget were also quantified. The daily evapotranspiration during the measurement period (mid May to mid October) ranged from 0.9 to 6.0 mm day-1, with a seasonal average of 3.6mm day-1.
Keywords: Eddy correlation technique, methane flux, peatlands
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Verma,
Dept. of Agric. Meteorology, University of Nebraska, P.O. Box 830728, Lincoln, NE-68583-0728, U.S.A.
Sähköposti:
ei.tietoa@nn.oo
- Ullman, Sähköposti: ei.tietoa@nn.oo
- Shurpali, Sähköposti: ei.tietoa@nn.oo
- Clement, Sähköposti: ei.tietoa@nn.oo
- Kim, Sähköposti: ei.tietoa@nn.oo
- Billesbach, Sähköposti: ei.tietoa@nn.oo
Depth distribution of methane production and oxidation in a Sphagnum peat bog.
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The anaerobic production and potential aerobic oxidation of methane were assessed in a Sphagnum-dominated peatland in Sweden. Peat from four depths in the 0-40 cm (below the vegetation surface) layer was collected in three different plant communities. The rate measurements were made with peat slurries in flasks. The ratio between the mean production and mean oxidation activities was more than ten-fold higher in the two wetter than in the driest community. The within profiles depth distributions of methanogenic and methane-oxidizing activity were similar, showing that a particular level may act as a net source or a net sink for methane, depending on prevailing environmental conditions (primarily the oxygen distribution). The results also suggest that methane production and consumption processes can occur in anaerobic and aerobic micro-zones in very close proximity to each other.
Key words: Carbon flow, methane oxidation, methane production, peatlands
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Sundh,
Department of Microbiology, Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden
Sähköposti:
ei.tietoa@nn.oo
- Nilsson, Sähköposti: ei.tietoa@nn.oo
- Svensson, Sähköposti: ei.tietoa@nn.oo
A mobile automatic gas chromatograph system to measure C02, CH4 and N2O fluxes from soil in the field.
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A caravan has been converted into a mobile laboratory for measuring fluxes of C02, CH4 and N2O from the soil in the field. The caravan is equipped with a gas chromatograph fitted with TC-, FI- and EC-detectors, and a PC controlled data logger. The gas collecting chambers can be used up to 50 m from the caravan. The closing and opening of the chambers, as well as the flows of sample gases from chambers to the gas chromatograph, is pneumatically regulated. Simultaneous recordings of temperature, light intensity and the depth of water table are made. The system has been used for two months in 1992, and some preliminary results are presented.
Keywords: Automated measuring, carbon dioxide, methane, nitrous oxide, peatland
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Silvola,
Department of Biology, University of Joensuu, P.O. Box III, FIN-80I0I Joensuu, Finland
Sähköposti:
ei.tietoa@nn.oo
- Martikainen, Sähköposti: ei.tietoa@nn.oo
- Nykänen, Sähköposti: ei.tietoa@nn.oo
The effect of changing water table on methane fluxes at two Finnish mire sites.
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Methane fluxes were measured using a static chamber technique on a minerotrophic fen and an ombrotrophic peat bog site located on the Lak-kasuo mire complex in central Finland. Both sites consisted of a virgin area and an area drained in 1961 by ditching. The measurements in 1991 were made biweekly from spring thaw to winter freezing. During this period, the mean CH4 emission from the virgin minerotrophic site and virgin ombrotrophic site was 98 mg m-2 d-1 and 40 mg m-2 d-1 , respectively. The mean emission of CH4 from the drained ombrotrophic site was 18 mg m-2 d-1. The drained minerotrophic site consumed methane during most of the measuring period, the average uptake was 0.13 mg m-2 d-1. Draining had lowered the average water table by 4 cm at the ombrotrophic site and by 20 cm at minerotrophic site. The possible reasons for the different development of the water table and methane fluxes at ombrotrophic and minerotrophic sites after draining are discussed.
Keywords: Drainage, methane flux, methane oxidation, nutrient status, peat soil
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Martikainen,
Department of Environmental Microbiology, National Public Health Institute, P.O. Box 95, FIN-70701 Kuopio, Finland
Sähköposti:
ei.tietoa@nn.oo
- Nykänen, Sähköposti: ei.tietoa@nn.oo
- Crill, Sähköposti: ei.tietoa@nn.oo
- Silvola, Sähköposti: ei.tietoa@nn.oo
Isotope geochemistry of gas and water samples from deep peats in boreal Canada.
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A number of determinations of carbon isotopes of gas from deep peats in northern Ontario, Canada are presented, 14C contents of both C02 and CH4 are higher than in adjacent peats indicating younger sources of carbon for their production with transport of these sources or of the gases themselves. High tritium levels indicate the presence of water derived from relatively recent precipitation and hydraulic gradients within the peat show that significant vertical water movement is possible. These preliminary results suggest that the carbon dynamics of boreal peatlands are far more complex than is generally realised.
Keywords: Carbon dioxide, carbon isotopes, methane, tritium, water movement
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Charman,
University of Plymouth, Plymouth, Devon, PL4 8AA. UK
Sähköposti:
ei.tietoa@nn.oo
- Aravena, Sähköposti: ei.tietoa@nn.oo
- Warner, Sähköposti: ei.tietoa@nn.oo
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