Evapotranspiration of forests in Fennoscandia - a synthesis based on eddy-covariance data and modeling

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The effects of land use on organic carbon, nitrogen and phosphorus export in boreal catchments

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Metsätalouden vesistökuormituksen seuranta- ja raportointiohjelma

Metsätalouden vesistökuormituksen seurantaverkon muodostavat luonnon taustakuormituksen ja normaalin metsätaloustoiminnan aiheuttaman kuormituksen seurantaan perustetut latvavaluma alueet. Verkon avulla voidaan tuottaa valtakunnalliset sekä vesienhoitoalue- ja jokivaluma-aluekohtaiset arviot metsätalouden aiheuttamasta kuormituksesta ja seurata esim. muuttuvista ilmasto-oloista tai metsätalouden intensiteetin muutoksista aiheutuvia trendejä. Seurantaverkko perustettiin vuonna 2014 ja seurantaa toteutetaan yhteistyössä Luonnonvarakeskuksen, Suomen ympäristökeskuksen (SYKE), Metsähallituksen, Suomen Metsäkeskusten, ELY-keskusten ja Tapio Oy:n kanssa. Näytteenottoa ja laboratorioanalyysejä on ulkoistettu yksityisille toimijoille. Tämä raportti kuvaa seurantaverkkoon kuuluvat valuma-alueet, aineiston keruumenetelmät ja tulosten laskennan.201

Kunnostusojituksen tarpeellisuuden arviointi mallinnuksen keinoin

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Soil concentrations and soil-atmosphere exchange of alkylamines in a boreal Scots pine forest

Alkylamines are important precursors in secondary aerosol formation in the boreal forest atmosphere. To better understand the behavior and sources of two alkylamines, dimethylamine (DMA) and diethylamine (DEA), we estimated the magnitudes of soil-atmosphere fluxes of DMA and DEA using a gradient-diffusion approximation based on measured concentrations in soil solution and in the canopy air space. The ambient air concentration of DMA used in this study was a sum of DMA and ethylamine. To compute the amine fluxes, we first estimated the soil air space concentration from the measured soil solution amine concentration using soil physical (temperature, soil water content) and chemical (pH) state variables. Then, we used the resistance analogy to account for gas transport mechanisms in the soil, soil boundary layer, and canopy air space. The resulting flux estimates revealed that the boreal forest soil with a typical long-term mean pH 5.3 is a possible source of DMA (170 +/- 51 nmolm(-2) day(-1)) and a sink of DEA (-1.2 +/- 1.2 nmolm(-2) day(-1)). We also investigated the potential role of fungi as a reservoir for alkylamines in boreal forest soil. We found high DMA and DEA concentrations both in fungal hyphae collected from field humus samples and in fungal pure cultures. The highest DMA and DEA concentrations were found in fungal strains belonging to decay and ectomycorrhizal fungal groups, indicating that boreal forest soil and, in particular, fungal biomass may be important reservoirs for these alkylamines.Peer reviewe

A look at aerosol formation using data mining techniques

International audienceAtmospheric aerosol particle formation is frequently observed throughout the atmosphere, but despite various attempts of explanation, the processes behind it remain unclear. In this study data mining techniques were used to find the key parameters needed for atmospheric aerosol particle formation to occur. A dataset of 8 years of 80 variables collected at the boreal forest station (SMEAR II) in Southern Finland was used, incorporating variables such as radiation, humidity, SO2, ozone and present aerosol surface area. Data analysis were done using clustering and classification methods. The aim of this approach was to gain new parameters independent of any subjective interpretation. This resulted in two key parameters, relative humidity and preexisting aerosol particle surface (condensation sink), capable in explaining 88% of the nucleation events. The inclusion of any further parameters did not improve the results notably. Using these two variables it was possible to derive a nucleation probability function. Interestingly, the two most important variables are related to mechanisms that prevent the nucleation from starting and particles from growing, while parameters related to initiation of particle formation seemed to be less important. Nucleation occurs only with low relative humidity and condensation sink values. One possible explanation for the effect of high water content is that it prevents biogenic hydrocarbon ozonolysis reactions from producing sufficient amounts of low volatility compounds, which might be able to nucleate. Unfortunately the most important biogenic hydrocarbon compound emissions were not available for this study. Another effect of water vapour may be due to its linkage to cloudiness which may prevent the formation of nucleating and/or condensing vapours. A high number of preexisting particles will act as a sink for condensable vapours that otherwise would have been able to form sufficient supersaturation and initiate the nucleation process