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CO₂ and CH₄ gas fluxes from northern boreal river Kitinen

Show simple item record 2020-06-05T10:17:05Z 2020-06-05T10:17:05Z 2020-06-05
dc.title CO₂ and CH₄ gas fluxes from northern boreal river Kitinen en
ethesis.discipline.URI none und
ethesis.faculty Bio- ja ympäristötieteellinen tiedekunta fi
ethesis.faculty Faculty of Biological and Environmental Sciences en
ethesis.faculty Bio- och miljövetenskapliga fakulteten sv
ethesis.faculty.URI Helsingin yliopisto fi University of Helsinki en Helsingfors universitet sv
dct.creator Skogberg, Mikko
dct.issued 2020
dct.language.ISO639-2 eng
dct.abstract Static floating chamber (FC) measurements of CH₄ and CO₂ fluxes from northern boreal river Kitinen were analyzed for this thesis. Measurements were carried out in summer 2018. Spatiotemporal variability was measured in the fluxes by comparing three chamber measuring locations: the opposite river banks and the middle of the river. Mean CO₂ flux estimate was 0.83±0.54 μmol CO₂ m⁻² s⁻¹ (mean ± SD, n = 73), consistent with other estimates for similar systems, with a corresponding k₆₀₀ CO₂ gas transfer velocity estimate of 17±9 cm h⁻¹ . Nonlinear modelling of CO₂ flux was found useful for analyzing floating chamber data from a river. The mean CH₄ flux was 0.0084±0.0047 μmol CH₄ m⁻² s⁻¹ , slightly lower than the median for different river systems in literature. The flux estimates were compared with eddy covariance measurements (EC). FC measurements are expected to give larger results, but additionally chambers are known to overestimate fluxes in flowing water. The comparison yielded chamber fluxes 3.3 and 2.9 times the EC median values for CO₂ and CH₄ respectively. Fluxes were similar between the three locations, and they peaked in late July for both gases in all loca- tions. Some differences over the river cross-section were observed. Discharge was significantly correlated to fluxes in the middle of the river, which could be explained by inhomogeneous flow. On two measuring days in early August, the mid-river CO₂ fluxes were three times those observed near the banks. The difference was also measured in methane. No clear cause was determined, but measuring spatial variation in surface water gas concentrations and flow could clarify the causes of similar observations in further studies. en
dct.subject Floating chamber en
dct.subject Northern boreal river en
dct.subject Carbon dioxide en
dct.subject Methane en
dct.subject Spatial variability of fluxes en
dct.language en
ethesis.language English en
ethesis.language englanti fi
ethesis.language engelska sv
ethesis.supervisor Ojala, Anne
ethesis.supervisor Vesala, Timo
ethesis.supervisor Mammarella, Ivan
ethesis.thesistype pro gradu -tutkielmat fi
ethesis.thesistype master's thesis en
ethesis.thesistype pro gradu-avhandlingar sv
dct.identifier.ethesis E-thesisID:d2dad351-886d-49aa-bf48-5a0e3025d676
ethesis-internal.timestamp.reviewStep 2020-03-24 08:54:16:564
ethesis.principalprofessor Korhola, Atte
dct.identifier.urn URN:NBN:fi:hulib-202006052626
dc.type.dcmitype Text
ethesis.facultystudyline Ympäristömuutos fi
ethesis.facultystudyline Environmental Change en
ethesis.facultystudyline Miljöförändring sv
ethesis.facultystudyline.URI und
ethesis.mastersdegreeprogram Ympäristömuutoksen ja globaalin kestävyyden maisteriohjelma fi
ethesis.mastersdegreeprogram Master's Programme in Environmental Change and Global Sustainability en
ethesis.mastersdegreeprogram Magisterprogrammet i miljöförändringar och global hållbarhet sv
ethesis.mastersdegreeprogram.URI und

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