Merkouriadi, I., Leppäranta, M. & Shirasawa, K. 2013: Seasonal and annual heat budgets offshore the Hanko Peninsula, Gulf of Finland. Boreal Env. Res. 18: 89–108.
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Hyvönen, N. P., Huttunen, J. T., Shurpali, N. J., Lind, S. E., Marushchak, M. E., Heitto, L. & Martikainen, P. J. 2013: The role of drainage ditches in greenhouse gas emissions and surface leaching losses from a cutaway peatland cultivated with a perennial bioenergy crop. Boreal Env. Res. 18: 109–126.
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Lappalainen, H. K., Sevanto, S., Dal Maso, M., Taipale, R., Kajos, M., Kolari, P. & Bäck, J. 2013: A source-orientated approach for estimating daytime concentrations of biogenic volatile organic compounds in an upper layer of a boreal forest canopy. Boreal Env. Res. 18: 127–144.
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Schobesberger, S., Väänänen, R., Leino, K., Virkkula, A., Backman, J., Pohja, T., Siivola, E., Franchin, A., Mikkilä, J., Paramonov, M., Aalto, P.P., Krejci, R., Petäjä, T. & Kulmala, M. 2013: Airborne measurements over the boreal forest of southern Finland during new particle formation events in 2009 and 2010. Boreal Env. Res. 18: 145–163.
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Saari, P., Saarnio, S., Heinonen, J. & Alm, J. 2013: Emissions and dynamics of N₂O in a buffer wetland receiving water flows from a forested peatland. Boreal Env. Res. 18: 164–180.
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Merkouriadi, I., Leppäranta, M. & Shirasawa, K. 2013: Seasonal and annual heat budgets offshore the Hanko Peninsula, Gulf of Finland. Boreal Env. Res. 18: 89–108.

A joint Finnish–Japanese sea-ice experiment 'Hanko-9012' carried out offshore the Hanko Peninsula included seasonal monitoring and intensive field campaigns. Ice, oceanographic and meteorological data were collected to examine the structure and properties of the Baltic Sea brackish ice, heat budget and solar radiation transfer through the ice cover. Here, the data from two years (2000 and 2001) are used for the estimation of the seasonal and annual heat budgets. Results present the surface heat balance, and the heat budget of the ice sheet and the waterbody. The ice cover acted as a good control measure of the net surface heat exchange. Solar radiation had a strong seasonal cycle with a monthly maximum at 160 and a minimum below 10 W m^–2, while net terrestrial radiation was mostly between –40 and –60 W m^–2. Latent heat exchange was much more important than sensible heat exchange, similar the net terrestrial radiation values in summer and autumn. A comparison between the latent heat flux released or absorbed by the ice and the net surface heat fluxes showed similar patterns, with a clearly better fit in 2001. The differences can be partly explained by the oceanic heat flux to the lower ice boundary.

Hyvönen, N. P., Huttunen, J. T., Shurpali, N. J., Lind, S. E., Marushchak, M. E., Heitto, L. & Martikainen, P. J. 2013: The role of drainage ditches in greenhouse gas emissions and surface leaching losses from a cutaway peatland cultivated with a perennial bioenergy crop. Boreal Env. Res. 18: 109–126.

We studied greenhouse gas (GHG) emissions from drainage ditches and leaching losses in a boreal cutaway peatland cultivated with reed canary grass (Phalaris arundinacea) for bioenergy. The objectives of the study were to assess to what extent GHG emissions from drainage ditches and leaching of carbon and nutrients via surface drainage contribute to the total losses of carbon and nitrogen from the site. The emissions of CH₄, N₂O and CO₂ were measured with static chamber methods for three years and leaching losses for seven years. On average, the drainage ditches (covering 6% of the study site area) released 10% of the total CH₄ emission (0.33 g m^–2 a^–1), and 1% and 5% of the total N₂O and CO₂ emissions, respectively. Leaching of total nitrogen and phosphorous were 0.31 and 0.03 g m^–2 a^–1, respectively. Leaching values were lower than those reported for agricultural catchments in general.

Lappalainen, H. K., Sevanto, S., Dal Maso, M., Taipale, R., Kajos, M., Kolari, P. & Bäck, J. 2013: A source-orientated approach for estimating daytime concentrations of biogenic volatile organic compounds in an upper layer of a boreal forest canopy. Boreal Env. Res. 18: 127–144.

Biologically justified statistical models for daytime atmospheric concentrations of methanol, acetaldehyde, acetone, isoprene and monoterpene were tested using measurements at a boreal forest stand in southern Finland in 2006–2007 and in summer 2008. The canopy-scale concentrations of all compounds except monotepene were closely correlated with shoot-scale concentrations indicating a strong link to biological emission source. All the models were based on the exponential relationship between air temperature and atmospheric concentration of biogenic volatile organic compounds (BVOCs). The first model — an exponential function of air temperature (T model) — could explain 27%–64% of the variation in BVOC daytime concentrations in the test data. The second model — a Temperature-State of Development model (T-S model) having two explaining variables (air temperature and seasonal photosynthetic efficiency) — was derived from an empirical adjustment of seasonality. This model slightly increased the fraction of explained variation but it still could not explain the high concentration peaks, which accounted for most of the unexplained variation. To better analyse these peaks we tested the Trigger model including two potential environmental triggers, a PAR index (high photosynthetically active photon flux density (PAR) and high ozone concentration, that could increase the concentrations momentarily. However, the Trigger model described the peak concentrations only somewhat better than the T or T-S model. It seems that it is very difficult to explain more than 32%–67% of variation in BVOC concentrations by a straightforward source-oriented modelling without deep understanding of biological and physical processes. In order to improve the models profound studies on specific stress factors and events inducing BVOC emissions are needed.

Schobesberger, S., Väänänen, R., Leino, K., Virkkula, A., Backman, J., Pohja, T., Siivola, E., Franchin, A., Mikkilä, J., Paramonov, M., Aalto, P.P., Krejci, R., Petäjä, T. & Kulmala, M. 2013: Airborne measurements over the boreal forest of southern Finland during new particle formation events in 2009 and 2010. Boreal Env. Res. 18: 145–163.

We conducted airborne observations of aerosol physical properties over the southern Finland boreal forest environment. The aim was to investigate the lower tropospheric aerosol (up to 4-km altitude) over an area of 250 by 200 km, in particular during new particle formation (NPF) events, and to address the spatial variability of aerosol number concentration and number size distribution. The regional NPF events, detected both airborne and at the ground, with air masses originating from the Arctic or northern Atlantic Ocean were studied throughout the boundary layer and throughout the area covered. Three suitable case studies are presented in more detail. In two of these studies, the concentrations of nucleation mode particles (3–10 nm in diameter) were found considerably higher (up to a factor of 30) in the upper parts of the planetary boundary layer compared to ground-based measurements during the nucleation events. The observed vertical variation can be connected to boundary layer dynamics and interactions between the boundary layer and the lower free troposphere, likely yielding high concentrations of newly formed aerosol particles. Our results suggest that nucleation does not necessarily occur close to the surface. In one presented case we found evidence of NPF occurring in a limited area above cloud, in the complete absence of a regional NPF event.

Saari, P., Saarnio, S., Heinonen, J. & Alm, J. 2013: Emissions and dynamics of N₂O in a buffer wetland receiving water flows from a forested peatland. Boreal Env. Res. 18: 164–180.

Forestry operations can cause disturbances in nutrient cycling. Protection of watercourses by trapping the leached solids and nutrients in sedimentation ponds and buffer zones may create a new greenhouse gases (GHG) source. We measured in situ nitrous oxide (N₂O) fluxes in different parts of a spruce swamp buffer zone, N₂O emissions from intact peat columns after fertilization with different ammonium nitrate (NH₄NO₃) levels, and the rate and volume of in vivo N₂O accumulation. N₂O-producing micro-organisms existed throughout the buffer zone. The rate of N₂O formation was highest at depths close to the prevailing water table within the buffer zone. Groundwater level and the vicinity of bypass water flows at the soil surface regulated the spatial and temporal variation in the rate of N₂O efflux in the field. Nitrogen (N) addition rapidly increased in vivo N₂O release. Microbial activity in the laboratory incubations under optimal conditions was high, but the in situ N₂O efflux in the field was low. The actual leaching of mineral N from forestry areas was low and the inorganic N concentration in the buffer zone inflow was no higher than is typical for humic brooks or lakes in Finland. The low N₂O fluxes indicated that forestry operations in the catchment did not result in significant N enrichment of the buffer zone. This study does not support the postulate that peatland buffer zones may become significant sources of N₂O.