The 100 most-cited articles in Työväentutkimus Vuosikirja, 2024

We analyzed size distributions measured continuously at a boreal forest measurement site at Hyytiälä, Finland between 1996 and 2003. From the eight-year data we identified days when new aerosol particle formation was taking place as well as days when no formation was detected, removing days with ambiguous status. The event days were then classified based on whether it was possible to determine formation and growth rates of new particles. These characteristics were then calculated. We found that new particle formation happens frequently in the boreal forest boundary layer, with at least 24% of days containing an event. Events are more probable during spring and autumn than during other times of the year. The average formation rate of particles larger than 3 nm was 0.8 cm–3 s–1, with enhanced rates during spring and autumn. The mean growth rate was 3.0 nm h–1, peaking in summer. The created event database is valuable for future studies of reasons leading to new particle formation in the atmosphere.

The application of the lake model FLake to represent the effect of lakes in numerical weather prediction (NWP) and climate models is discussed.As a lake parameterisation scheme FLake is implemented into the limited-area NWP model COSMO.Results from a numerical experiment with the coupled COSMO-FLake system, including the complete COSMO-model data assimilation cycle, indicate a good performance with respect to the lake surface temperature and to the freeze-up of lakes and the ice break-up.The use of FLake removes a significant overestimation of the lake surface temperature during winter that is typical of the routine COSMO sea surface temperature analysis.Some challenging issues are discussed, such as the development of external-parameter fields and the lake temperature spin-up following a cold start of FLake in an NWP or climate model.

On the basis of fifteen global model simulations of future climate, using the SRES emissions scenarios for greenhouse gases and aerosols, we have constructed national-scale seasonal and annual climate change scenarios for Finland during the 21st century. In approximate terms, the annual mean temperature is projected to rise by 1–3 °C and the annual mean precipitation by 0%–15% by the 2020s, relative to the baseline period 1961–1990. The corresponding increases by the 2050s are 2–5 °C (temperature) and 0%–30% (precipitation), while by the 2080s they are 2–7 °C and 5%–40%, respectively. The projected temperature trends are markedly stronger than that observed during the 20th century. The ranges in the climate change projections reflect the uncertainties arising from differences in model formulation and in emissions scenarios but are, to some extent, affected by the internal variability of climate as well. Seasonally, the projected precipitation changes and their statistical significance are largest in winter and smallest in summer. On the other hand, the projected rather small…

A regional coupled ocean-atmosphere-ice general circulation model for northern Europe is introduced for climate study purposes. The Baltic Sea is interactively coupled. The coupled model is validated in a 5-year hind-cast experiment with a focus on surface quantities and atmosphere-ocean heat fluxes. The coupled sea surface temperature matches observations well. The system is free of drift, does not need flux corrections and is suitable for multi-year climate runs. With flux forcing from the atmospheric model the regional ocean model gives sea surface temperatures statistically equivalent to the uncoupled ocean model forced by observations. Other oceanic surface quantities do not reach this quality in combination with the current atmosphere model. A strong dependence of sea ice extent on details of the atmospheric radiation scheme is found. Our standard scheme leads to an overestimation of ice, most likely due to a negative bias of long-wave radiation. There is indication that a latent heat flux bias in fall contributes to the ice problem. Other atmosphere-ocean heat fluxes are…

The multi log-normal distribution function is widely in use to parameterize the aerosol particle size distributions. The main purpose of such a parameterization is to quantitatively describe size distributions and to allow straightforward comparisons between different aerosol particle data sets. In this study, we developed and evaluated an algorithm to parameterize aerosol particle number size distributions with the multi log-normal distribution function. The current algorithm is automatic and does not need a user decision for the initial input parameters; it requires only the maximum number of possible modes and then it reduces this number, if possible, without affecting the fitting quality. The reduction of the number of modes is based on an overlapping test between adjacent modes. The algorithm was evaluated against a previous algorithm that can be considered as a standard procedure. It was also evaluated against a long-term data set and different types of measured aerosol particle size distributions in the ambient atmosphere. The evaluation of the current algorithm showed the…

Measurements of rain were obtained with a vertically pointing micro radar (MRR) with 1 min time resolution and 50(100) m height resolution at the German Baltic coast on the Zingst peninsula (54.43°N, 12.67°E). The comparison with a conventional rain gauge (30 min integration time) for a five months summer period show a correlation coefficient of [[rho][eta][omicron]] = 0.87 for the rainrate and agreement within 5% for the total rainfall integrated over the whole period. Single measurements with 30 min integration time showed deviations up to a factor of 2 between MRR and rain gauge. Classification of the measurements into rainrate intervals shows that rainrates around 0.2 mm h–1 provide the highest contribution per rainrate interval to the total rainfall. Typical distributions of number-concentration, liquid-water- concentration and rainrate versus drop size, retrieved with the MRR, are presented. Simultaneous estimates of rainrate and reflectivity factor with data of a C-band (frequency 6 GHz) weather radar suggest that the MRR may be used to support quantitative rainrate estimates…

We present nearly six years of measurements of surface fluxes of momentum, sensible heat, water vapour, carbon dioxide and aerosol particles, along with a three-month time series of ozone flux, measured by eddy covariance above a Scots pine forest in southern Finland from April 1996 to December 2001. The results show marked seasonal and diurnal variation and a significant effect of local and remote anthropogenic pollution on CO2 and particle data. The flux of inert CO2 followed environmental factors through plant and soil-microbe metabolism very closely. The flux of reactive O3 depended on the overlapping influences of environmental parameters driving photosynthesis and of the available amount of reaction partners. The flux of multireactive aerosol particles showed no clear connection with any environmental variable. On new-particle-formation days, the average deposition velocity of particles was, however, greater than usual because small nucleation-mode particles have greater deposition velocities than do larger accumulation-mode particles.

continuous monitoring of air pollution and surface-atmosphere interactions

The impact of lakes on the European climate is considered by analysing two 30-year regional climate model (RCM) simulations.The RCM applied is the Rossby Centre regional climate model RCA3.5.A simulation where all lakes in the model domain are replaced by land surface is compared with a simulation where the effect of lakes is accounted for through the use of the lake model FLake coupled to RCA.The difference in 2m open-land air temperature between the two simulations shows that lakes induce a warming on the European climate for all seasons.The greatest impact is seen during autumn and winter over southern Finland and western Russia where the warming exceeds 1 °C.Locally, e.g. over southern Finland and over Lake Ladoga, the convective precipitation is enhanced by 20%-40% during late summer and early autumn while it is reduced by more than 70% over Lake Ladoga during early summer.

Meteorological parameters of windstorm Gudrun on 8–9 January 2005 and its hydrodynamic and environmental consequences are analysed on the basis of observational data and hydrodynamic modelling. The study focuses mainly on describing events and reception in Estonia. We estimate that in meteorological terms, the cyclone was among the five most powerful ones in recorded history. Considering also the new highest storm surge record (275 cm in Pärnu), extensive property damage and massive media coverage, it became the most influential natural disaster in Estonia. Using a shallow sea 2D hydrodynamic model with a 1-km grid step, a hindcast modelling study of the sea level was carried out. Hydrodynamic simulations suggest that an inflow of 24 km3 (5.4% of the Gulf's average volume) occurred in the Gulf of Riga. The sub-basin of the Väinameri was nearly entirely flushed through by more saline and nutrient-poorer water from the Baltic Proper. The simulated current velocities, sea levels and wave parameters indicate that prominent coastline changes and replacement of sediments could have…

Phytophthora is a genus of aquatic plant pathogens well known as disease agents in agriculture and forestry.They are water molds, Oomycetes, with swimming zoospores and thick-walled resting spores.Many species are benign in coevolved plant communities, but given the opportunity of introduction to new hosts in new environments, new opportunities for dispersal, or unexpected sexual recombination, they are causing dramatic epidemics in forests around the world.Phytophthora ramorum (cause of sudden oak death in western North America and also damaging in Europe) provides a current example, dramatically illustrating the potential of these pathogens for rapid ecological (and economic) damage.Phytophthora cinnamomi and P. lateralis are also alien to Europe and North America but with different epidemiological strategies.By comparing these three related pathogens and the different consequences of their invasions, some predictions for the future of our forests are possible.

A new multi-channel air ion spectrometer (AIS) is presented. The instrument allows simultaneous measurements of positive and negative ion distributions from 3.2 to 0.0013 cm 2 V -1 s -1 (0.80-40 nm diameter or, using the Tammet correction, from 0.4 to 40 nm). The mobility range is divided into 27 fractions which are measured simultaneously to ensure a high time resolution (down to 10 seconds). The instrument calibration shows a good agreement with the mobility of electrically-classified, mono-dispersed aerosols. The spectrometer overestimates low concentrations of cluster ions. This is caused by a natural production of small ions (< 1 nm, 10 to 100 cm -3 ) inside the spectrometer. The instrument specifications, calibration results and measurements performed show a huge application potential of the new spectrometer.

We used six years of wave hindcasts, calculated by the wave model WAM, to compile wave statistics for the Baltic Sea.The wave model was implemented taking into account the special features of the Baltic Sea: irregular coastline, archipelago and ice.To our knowledge, there is no single way to present annual statistics in seasonally ice-covered seas.We discuss five different possibilities to calculate the statistics, and the differences between them.According to verification against wave buoy and satellite altimeter measurements, the quality of the hindcast significant wave height is sufficient for presenting reliable wave statistics.The mean values of the significant wave height are smaller than 1.5 m.According to the mean values and exceedance probabilities, the severest wave climate is in the Baltic Proper.The wave climate in the other basins is considerably less severe.The maximum hindcast significant wave height is over 9 m, whereas the measured maximum is 8.2 m.

The purpose of this paper is to introduce the gas exchange measurement and flux calculation methods commonly used in the projects of the programme "Greenhouse gas emissions from the use of peat and peatlands in Finland".The methods include measurements of instantaneous fluxes of CO 2 , CH 4 and N 2 O made at the ecosystem-atmosphere boundary using closed chamber, and whole ecosystem fluxes of the gases using micrometeorological EC tower extending above the canopy, and the integration of seasonal and annual fluxes.In addition, tools developed for gap filling of missing weather records, and generating complete weather patterns for the key environmental controls of the gas fluxes are introduced.Derivation of emission factors from the collected gas fluxes, capable of reproducing the dynamic, climate dependent nature is outlined.

We measured on annual basis the magnitude and relative importance of different components of the carbon balance of a boreal Scots pine dominated forest ecosystem.The continuous 10-year-long measurement period of this study and the miscellaneous measurements of the components of the ecosystem carbon balance carried out at the same site are almost unique.The ecosystem was shown to be a carbon sink in all measured years.The average net ecosystem exchange (NEE) estimated with the eddy covariance (EC) method was -206 g C m -2 a -1 and the average annual accumulation of carbon into trees was 242 g C m -2 a -1 .The above-ground litter production was 186 g C m -2 a -1 of which 92 g consisted of needles and leaves.The average respiration rates of the soil, canopy and stems were 646, 316 and 62 g C m -2 a -1 , respectively and the TER deduced from EC measurements was 826 g C m -2 a -1 .The average rate of the tree and ground vegetation photosynthesis was 982 and 114 g C m -2 a -1 , respectively.In forest ecosystems the application of biomass equations to measurements of tree dimensions and…

The concentration of suspended solids in a meso-eutrophic basin remained unchanged in the years following clear felling (1983–85). The amount of suspended solids increased upon ditching, ploughing and mounting to a mean level of 81.8 mg l–1 in 1986–88, decreased to a level of 7.8 mg l–1 for 1989–91 and 4.5 mg l–1 for 1992–94. Total phosphorus concentration increased four-fold (142 µg l–1) in 1983–85 following clear felling, and remained at three times the reference concentration (95.4 µg l–1) in 1986–88 following ditching and site preparation. Phosphate phosphorus concentration increased more than five-fold after clear felling (97.8 µg l–1) in 1983–85 and was more than two-fold the reference (39.5 µg l–1) following ditching and site preparation in 1986–88. The concentrations of total phosphorus and phosphate phosphorus returned to the level recorded in a natural state by 1989 onwards. Total nitrogen concentrations doubled (965 µg l–1) upon clear felling, and remained the same after ditching and site preparation in 1986–88. Where a protective strip of forest was left between the…

Smart-SMEAR is an interface to visualize the data measured at the SMEAR II station in Hyytiälä, Finland.It is designed to be an additional tool for data mining and a simple tool for working together with trace gas and aerosol data, meteorological parameters and air mass back-trajectories, including numerous point sources.The web tool acts as an interface to the station database which can be reached with only few mouse clicks.The tool provides an overview of such a complicated dataset.The database contains all the data from the start of continuous SMEAR II measurements in 1996 until today.Here, we present also some examples of how to use Smart-SMEAR.We present examples of one typical atmospheric nucleation event day, one local pollution event with low photochemical activity, and one long-range-transport pollution day coupled with local pollution events with strong solar radiation.Smart-SMEAR, together with its search engine Smart-Search, has proven to be an effi cient tool for studying atmospheric chemistry and atmospheric aerosol dynamics.

A systematic assessment of the ability of two selected 1-D lake models (the model of S.W. Hostetler and the Freshwater Lake model) to simulate lake surface temperature and fluxes for different lake conditions, corresponding to typical temperate freezing lakes of North America, through a set of offline tests, is presented. Results suggest that both models perform well in shallow lakes, while important differences between modelled and observed water temperatures and ice-cover duration can be noticed in deeper lakes. These differences could be partially attributed to the biases in the driving data and most importantly to the lack of representation of complex processes in the models, such as horizontal transfer of water and heat, ice drift, etc. Sensitivity of the models to lake depth, water transparency, explicit snow and snow/ice albedo is presented and possible ways of improving the performance of the 1-D lake models are proposed.

Relationships between soil nitrogen (N) pools, climate, and soil-texture class in well-drained Nordic forest soils may be used for upscaling of regional N budgets.Total soil N pools and C:N ratios were studied in forest soils in Fennoscandia and Denmark (55-70°N, 5-27°E) in boreal pine and spruce forest, boreal mixed forest, and nemoral forest types (beech, oak, mixed).Total N pools in 198 forest soil profiles were calculated from horizon thickness, bulk density, stone content and nitrogen concentration and related to climate and soil texture through multiple linear regressions.The top 100 cm of the mineral soil and the organic layer were included.C:N ratios were calculated from C and N concentrations in 10-cm depth sections.Total soil N pools ranged from 0.05 to 1.65 kg N m -2 and were positively correlated with mean annual temperature (MAT) and mean annual precipitation (MAP).The range of mean annual temperatures was -2 °C to 8.4 °C, and the range of mean annual precipitations was 282 to 2270 mm y -1 .Soil N pools were highly variable and related to climate and soil texture…

Long-term net ecosystem CO 2 exchange measurements were conducted on a nutrient-rich fen in northern Finland using the eddy covariance method.During the three measurement years (2006)(2007)(2008), the mean daytime CO 2 fl ux in July was -0.40 mg CO 2 m -2 s -1 , while in mid-winter (January-March) the mean effl ux was 0.008 mg CO 2 m -2 s -1 .Annual balances of -12, -123 and -216 g CO 2 m -2 a -1 were observed in 2006, 2007 and 2008, respectively.It is suggested that the low uptake in 2006 was related to the warm and dry conditions during the growing season and the consequent reduction in vegetation activity.When compared with two other fens in Finland, there was a clear correspondence between the nutrient status, mean pH value, maximum LAI and the mid-summer CO 2 uptake.A similar pattern was not seen in the annual CO 2 balance, which correlates more with the growing season length.

To understand the very fi rst steps of atmospheric particle formation and growth, measurements at the size where atmospheric nucleation occurs are crucially needed.We present number size distributions of > 0.8 nm ions and > 1.8 nm particles measured with the Neutral cluster and Air Ion Spectrometer (NAIS) at a boreal forest site in Hyytiälä, Finland, during 2006-2007.Pools of neutral and charged clusters seem to be present all the time below 3 nm.The total concentration of 1.8-3.0nm clusters was ~1000 cm -3 , ranging from 50 to 6000 cm -3 , whereas the concentrations of charged clusters in this size range remained below 50 cm -3 .On average, both neutral and charged clusters seem to have different diurnal cycles on particle formation event and non-event days.We also compared the NAISderived concentrations with those obtained from other concurrent air ion and particle instruments and found that the NAIS concentrations are in agreement with concentrations determined with these other instruments.

The lake model FLake was incorporated into the European Centre for Medium-Range Weather Forecasts (ECMWF) land-surface scheme HTESSEL. Results from global offline simulations are presented in order to evaluate the model performance in different climates and assess the impact of lake representation on the surface energy balance. The model was forced by ECMWF reanalysis ERA-Interim (1989―2005) near surface meteorology and surface radiation fluxes for the entire globe. Model validation includes lake surface temperatures and lake ice duration. The impact of the snow insulation on lake ice cover duration is discussed, as well as the sensitivity of results to the lake depth. Results show changes in the variation of surface energy storage, and changes in the partition of surface energy fluxes in high latitude and equatorial regions, respectively. General aspects concerning the incorporation of lake models into General Circulation Models for weather forecast and climate modelling are discussed.

The linkage between global climate change and sea level on the Finnish coast was studied. Scenarios were calculated for the long-term mean sea level in the future, based on the global change scenarios given by the Intergovernmental Panel on Climate Change. The effects of global mean sea level, local land uplift and the water balance of the Baltic Sea were taken into account. The effect of the water balance was estimated with the North Atlantic Oscillation (NAO) index. In most cases the rise in water level is expected to balance the land uplift in the Gulf of Finland, and the past declining trend of the relative sea level is not expected to continue. In the Gulf of Bothnia, the stronger land uplift rate still results in a fall of the relative mean sea level in the future. The uncertainties in the scenarios are large. Scenarios for the intra-annual variability of the sea level were constructed by extrapolating the 20th century trends of increasing variability.

We calculate structures and thermochemical parameters for H 2 SO 4 •(H 2 O) n , HSO 4 -•(H 2 O) n , H 2 SO 4 •NH 3 •(H 2 O) m and HSO 4 -•NH 3 •(H 2 O) m clusters (with n = 0 … 4 and m = 0 … 1) using the MP2/aug-cc-pV(D + d)Z quantum chemical method, with higher-order corrections computed at the MP2/aug-cc-pV(T + d)Z and MP4/aug-cc-pV(D + d)Z levels.Equilibrium constants for hydrate formation at different temperatures are computed using the quantum chemical results, and the predicted extent of hydrate formation is compared with experimental results.Hydrate distributions in different RH conditions are derived using the calculated free energies of hydration.The results show that the hydrogensulfate ion is in all conditions much more strongly hydrated than the neutral sulfuric acid molecule.The high-level thermodynamic data calculated for the clusters agree with the experimental data, and the presented hydrate model is expected to perform better than earlier versions based on less reliable quantum chemical data.A comparison to the ammonia-containing clusters indicates that ammonia…

In this paper, the research conducted on the emissions of the biogenic volatile organic compounds (BVOCs) from the European boreal zone, or taiga, is reviewed.We highlight the main fi ndings and the key gaps in our knowledge.Ecosystem scale BVOC emissions from the Eurasian taiga are observed to be relatively low as compared with those from some forest ecosystems in warmer climates.One of the distinctive features of the Eurasian taiga is the predominance of monoterpene emitting coniferous trees.Recent research indicates that in addition to evaporation from storage structures, part of the monoterpene emission of conifers originates directly from synthesis.Monoterpene emission from boreal deciduous trees originates mainly directly from synthesis.The boreal trees exhibit distinct intra-species variation in the monoterpene mixtures they emit.Important sources of isoprene in the Eurasian taiga include Norway spruce, open wetland ecosystems and some non-dominant woody species, such as European aspen and willows.Many boreal tree species also emit non-terpenoid compounds and highly reactive…

In the early 1990s, commercial and recreational fishermen in the Kalmar Sound of the Baltic Sea reported decreasing stocks of Eurasian perch (Perca fluviatilis) and northern pike (Esox lucius). Test fishing surveys confirmed regionally declining abundances of both species. Both pike and perch spawning were observed annually, but virtually no young-of-the-year were captured in surveys from 1997–1999. The rapid decrease of the stocks was probably a result of the widespread recruitment failure. Studies of potential causes of the recruitment failure were conducted in 1998–2000. Field experiments excluded suboptimal water quality in brackish water recruitment areas as regulatory factor. Laboratory tests did not indicate reproductive disturbances in parental fish that could be related to chronic toxicity or endocrine disruptions, as hatching success and yolk-sac larvae survival were not negatively affected. Exposure to filamentous algae (Pilayella sp.) and diatoms, common in the spawning areas, had only a slight negative effect on pike egg hatchability. Two hypotheses that could not be…

The VOC emission rates of 16 Betula pubescens and 15 Betula pendula trees were measured during the 1997 growing season in southern Finland. Since the monoterpene emission rates of Betula pubescens showed large variations between the tree specimen, these measurements were continued in 2000 with two different clones. Both Betula pubescens and Betula pendula had low monoterpene emission rates early summer, but after the leaves were fully grown, darker and harder, Betula pendula initiated high monoterpene emission rates, whereas Betula pubescens showed large tree-to-tree variations. One of the studied clones initiated higher emission rates after the leaves had matured, whereas the emission rates of the other clone decreased a little. Betula pubescens also emitted linalool and sesquiterpenes. Linalool was the dominant emitted compound in June but later in summer the linalool emissions declined. Also the monoterpene emission pattern changed in the course of the growing season; at the time of leaf expansion the emission was composed of different monoterpenes, but later sabinene and…

This study aims to investigate sea level variability on the coasts of Finland and its changes over the past 100 years. The sea level probability distributions have apparently changed in shape. The annual maximum sea levels show a significant increasing trend, the increase being concentrated in the latter half of the 20th century. Annual variability shows an apparent increasing trend with the most pronounced increase occurring in the 1960s and 1970s. This was confirmed by examining the standard deviations as well as the spectra of the sea level. Short-period variability of the order of only a few days shows long-term changes that well exceed random variations, and it is therefore permissible to interpret these variations as reflecting the variations of short-term meteorological phenomena. The variations are not the same in different basins, but a minimum in the 1960s and a subsequent increase in the wintertime variability up to the 1980s can be seen in all of them. In the Gulf of Finland a 30 year cycle was found in the short term variability. On the other hand, the overall trend…

A field station was established in a beech forest near Sorø, Denmark in the spring of 1996 to provide a platform for studies of atmosphere–biosphere interactions. The station is equipped with a 57-m mast and a 24-m scaffolding tower. The mast makes it possible to measure profiles of gaseous atmospheric compounds and meteorological variables and to undertake measurements of fluxes by the eddy covariance method. The tower gives access to the tree canopy where branch and leaf level exchange of water vapour and CO2 is measured. Soil-atmosphere exchange of gaseous compounds is investigated with gas flux chambers on the soil surface. Water-mediated transport of C and N is measured in throughfall, stemflow and soil water. The paper provides information on the site, vegetation, climate and soil and gives a description of the instrumentation and other technical installations at the site. The paper also presents and discusses example results from the measurements such as meteorological variables (temperature, wind speed, wind direction, radiation, rainfall and relative humidity), gaseous…

Human activities have enhanced the emissions of carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) from organic soils. Drained peat soils may turn into a source of CO 2 and N 2 O, whereas CH 4 emission may generally decrease after drainage. Agricultural use, including ploughing, fertilization and irrigation, further enhances the decomposition of peat, and CO 2 and N 2 O emissions. Cultivated organic soils are therefore significant sources of CO 2 and N 2 O. In this paper we report greenhouse gas emissions from cultivated organic soils, and from abandoned organic agricultural soils, i.e. from organic soils where cultivation practices have ceased. We found that CO 2 and N 2 O emissions from abandoned organic cropland soils do not generally decrease with time after agricultural practices have ceased, whereas CH 4 fluxes from the atmosphere into the soil may gradually increase after leaving cultivation.

The geological and geomorphological settings of annually laminated sediments in Finnish boreal lakes in southern and central Finland were investigated. The purpose of the study was to identify the key sedimentary environmental factors of the morphometric features and catchment sediment types that control varve deposition in lakes. Altogether nearly 300 lakes were surveyed, of which 180 basins were cored. 35 of the cored lakes were found to contain partially laminated and 13 completely laminated sediments. Statistical analyses of the lake dataset, which also includes 15 previously located lakes composing varved sediments, show that two groups of lakes are more favourable for the formation of varves than others. The first group includes the majority of previously located varved lakes and is characterized by small-sized, relatively deep basins in glaciofluvial deposits. The second group is characterized by fairly equal proportions of till, bedrock and fine-grained sediment in the catchment, and it is more dependent on the shape of the catchment and basin itself than maximum depth and…

2008: Fluxes of dissolved organic and inorganic nitrogen in relation to stand characteristics and latitude in scots pine and norway spruce stands in Finland.Boreal Env.Res. 13 (suppl.B): 3-21.We monitored the fluxes of nitrogen (N) compounds in throughfall (TF) and in percolation water (PW) in Scots pine and Norway spruce stands in Finland, and explored their dependence on N bulk deposition (BD) rates and general site and stand characteristics.During 1998-2004, N fluxes in BD, TF, and PW were low and remained relatively constant.Inorganic N was retained in the ecosystem (BD > TF > PW) more effectively in spruce stands, while the fluxes of dissolved organic nitrogen (DON) correspondingly increased.The canopy retention of inorganic N was correlated with the net increase in TF DON.BD DON was relatively constant, while the TF DON and BD deposition of inorganic N increased towards the south.DON accounted for 14% of the BD N, 48% of N in TF in spruce and 31% in pine stands, and 80% of the total N in PW.Stand characteristics (e.g.stand age) affected the TF fluxes of both inorganic N and…

In the Baltic Sea upwelling is an important process, especially in the coastal areas, causing vertical mixing and displacement of the water body. During thermal stratification, when the surface layer of the water is depleted of nutrients, upwelling plays a key role in replenishing the euphotic zone with the nutritional components necessary for biological productivity. Up to now, only a few comprehensive investigations have been carried out to study the locations of the main upwelling areas in the Baltic and how commonly these upwellings take place. Here, three-dimensional high-resolution modelling is used as a tool to statistically estimate an index reflecting the persistency of upwellings (downwellings) in various parts of the Baltic. This estimate is made for the summer season over the ten-year period from 1979 to 1988. The new idea in this paper is to use the persistency (stability) of the vertical velocity to define an upwelling index, instead of calculating the frequency of upwelling on the basis of changes in the sea-surface temperature, as is usually done. The model results…

The effects of land-use and land-use change on soil greenhouse gas (GHG) fluxes are of concern due to Kyoto Protocol requirements.To quantify the soil GHG-fluxes of afforested organic soils in Finland, chamber measurements of soil CO 2 , CH 4 and N 2 O fluxes were made during the years 2002 to 2005 on twelve organic soil cropland and six cutaway peatland sites afforested 9 to 35 years ago.The annual soil CO 2 effluxes were statistically modelled using soil temperature as the driving variable and the annual CH 4 and N 2 O fluxes were estimated using the average fluxes during the measurement period.Soil CO 2 effluxes on afforested organic soil croplands varied from 207 to 539 g CO 2 -C m -2 a -1 and on cutaway peatlands from 276 to 479 g CO 2 -C m -2 a -1 .Both the afforested organic soil cropland and cutaway peatland sites acted mainly as small sinks for CH 4 ; the annual flux ranged from -0.32 to 0.61 g CH 4 -C m -2 .Afforested organic croplands emitted more N 2 O (from 0.1 to over 3.0 g N 2 O-N m -2 a -1 ) than cutaway peatland sites (from 0.01 to 0.48 g N 2 O-N m -2 a -1 ).Due to…

Effect of toxic metals mobilised from Finnish acid sulphate soils on terrestrial and aquatic biota: a literature review

Limnological responses of three small forest lakes in eastern Finland to forest clear cutting and soil scarification (in 15–33% of their catchments) were studied in 1991–1994, and compared with one reference lake. Increases in the concentrations of total phosphorus and iron indicated an increased inorganic load whereas the increase in water colour and chemical oxygen demand suggested an increased load of organic matter. No such changes were recorded in the reference lake. No clear response in phytoplankton biomass to catchment forestry was recorded. However, the changes in species composition, e.g. a bloom of cyanobacteria in one of the lakes in autumn 1993, indicated a slight eutrophication. Periphyton growth increased after the forestry operations resulting in increased concentrations of chlorophyll a. Zooplankton densities, both cladocerans and copepods, increased slightly in two of the lakes. Zoobenthos abundance increased in all the study lakes but increased biomass was recorded in only one. Population structure and growth of perch (Perca fluviatilis) remained unchanged in all…

2 -induced terrestrial climate feedback mechanism: From carbon sink to aerosol source and back.

The effect of forest harvesting and subsequent site preparation on soil CO2 efflux was studied on a clear-cut site with five soil treatments, including mounding, exposed E- and C-horizons, and undisturbed soil with and without logging residue left on soil. Site preparation accounted for over 75% of the total variance in soil CO2 effluxes. Clear-cutting and removal of logging residue decreased instantaneous CO2 effluxes from the soil surface by 40%, whereas the highest instantaneous effluxes were measured from mounds and from undisturbed soil with logging residue. These sampling points showed effluxes twice as high as those in the control forest or in places where the logging residue was removed. The lowest instantaneous effluxes, about 18% of those in the control forest, were measured from the exposed C-horizon. Annual effluxes in the forest were 1900 g CO2 m–2 before harvesting and 3242, 2845, and 2926 g m–2 in the three successive years after harvesting in places with logging residue, but when logging residue was removed, the annual efflux decreased to pre clear-cutting levels.…

This study summarizes the present knowledge of Finnish peatland areas and carbon (C) storage in peat from 1950 to 2000.In 1950, approximately 8.8 million ha of the Finnish peatland area was still undisturbed and 1.4 million ha drained.In 2000, almost 55% (5.7 million ha) of the peatland area in Finland was drained for forestry, 38.4% (4.0 million ha) was undrained, 0.8% (85 000 ha) was in agriculture, 0.6% (60 000 ha) was under water reservoirs, 0.3% (35 000 ha) was under roads and 0.6% was in peat harvesting or had been removed from the harvesting business (63 000 ha).The change in mire area is considered relatively reliable, whereas the net changes in the actual C sequestration and the actual C storage change from 1950 to 2000 involves much more uncertainty.In 2000, the total C storage of Finnish peatland ecosystems was estimated at 5960 Tg, which includes 5304 Tg as peat.Since 1950, the C sequestration of undrained and drained peatlands (peat, plant biomass) basically compensated for the anthropogenic losses.The most important forms of anthropogenic C losses have occurred from…

In this study we follow seasonal changes in the phytoplankton community composition in a shallow, mostly freshwater lagoon of the Baltic Sea.Nutrient enrichment effects on the quantitative and structural development of phytoplankton communities were also evaluated during short-term experiments in small-size enclosures.Different periods featuring alternate regulatory patterns of phytoplankton seasonal succession in the Curonian lagoon were derived.The spring phase is characterized by silica and phosphorus-limited conditions where nitrogen is a secondary limiting nutrient.Soluble inorganic phosphorus limits green algae, while silica limits diatoms, exclusively pennate species.In the enrichment experiments growth of centric diatom species was favoured by nitrogen addition, while pennates reaction was negative.Cyanobacteria dominated summer community is characterized by the nitrogen limitation, while phosphorus occurs as the secondary limiting factor.In general, inorganic nutrient concentrations in the hypereutrophic Curonian lagoon are too high to limit total plankton biomass, which is…

The eddy covariance method was used to determine turbulent heat fluxes and CO2 flux below a boreal Scots pine canopy 3 m above the forest floor. Data were filtered using standard deviation of the vertical velocity as a measure of the turbulent mixing in the trunk space along with the non-stationary criterion. The turbulent transfer in the trunk space was dominated by large (15–100 m) intermittent eddies, which were detectable by the eddy covariance technique. Heat fluxes exhibited clear annual and diurnal course and amounted to 20%–30% of the fluxes above the canopy. The forest floor was a source of carbon all-year-round and the CO2 efflux was mainly controlled by soil temperature. Photosynthesis of the forest floor vegetation decreased daytime fluxes of CO2 by 1.0–1.5 µmol m–2 s–1 compared with nocturnal values (~3.0 µmol m–2 s–1). The eddy covariance method provided a similar daily cycle to the chamber method but there was a discrepancy between their mean levels.

Number size distributions of particles and ions were measured with a differential mobility particle sizer and two different ion spectrometers at the SMEAR II station in southern Finland during April 2003–April 2004. Cluster ion (diameter < 1.6 nm) concentrations varied between 200 and 1500 cm–3, while the concentrations of intermediated ions (1.6–6.3 nm) remained usually below 200 cm–3. During the 70 observed nucleation event days, particle growth rates were strongly dependent on their size. The median diameter growth rates of particles in size classes 7–20 nm, 3–7 nm and 1.3–3 nm were 4–5 nm h–1, 2–4 nm h–1 and < 2 nm h–1, respectively. The growth rates of the smallest ions/particles were almost independent of the season having a minimum during the summer, whereas the growth rates of larger particles had a clear annual cycle with the highest values during the summer and lowest values during the winter. The results indicate that in addition to sulphuric acid, compounds related to photosynthesis participate in the particle growth, especially in the size class 7–20 nm.

gradients in the marine boundary layer -a multi-platform study.

external data for lake parameterization in numerical Weather Prediction and climate modeling.Boreal Env.

Mass populations of cyanobacteria are increasingly attracting the attention of environment agencies, water authorities, and human and animal health organizations, since they can present a range of water quality and treatment problems as well as hazards to human and animal health. The problem is especially severe in the Baltic Sea where cyanobacterial blooms occur every summer covering areas of more than 100000 km2. We studied optical properties of several phytoplankton species (including cyanobacteria) present in the Baltic Sea region. The measurements results were used in a bio-optical model together with optical properties of other phytoplankton species from literature. Our results show that cyanobacteria have a characteristic double feature (peak at 650 nm and phycocyanin absorption feature near 630 nm) in their reflectance spectra which can be detected by remote sensing instruments. Our estimation for the open Baltic Sea waters shows that concentration of chlorophyll has to be 8–10 mg m–3 before the double feature becomes detectable by remote sensing instruments which spectral…

On-line measurements of atmospheric VOC concentrations in the European boreal zone with a proton transfer reaction mass spectrometer were conducted at SMEAR II station in Hyytiälä, south-western Finland on 2–22 July 2004. The measurements showed a strong diurnal variation of several compounds. A factor analysis performed for the concentration data was used to classify the measured VOC masses into three classes based on the behavior of their concentrations. The masses in the first class had a high diurnal variation with maximum values in the afternoon. Compounds contributing to masses in this category were e.g. methanol, acetone, methyl-vinyl-ketone and hexanal. The concentrations of masses in the second class had also a high diurnal variation, but with maxima during the night when the mixing of the atmospheric surface layer was weak. Monoterpenes and phenol are compounds contributing to the masses in this category. The masses in the third class did not have a marked diurnal cycle and were not dependent on the local meteorological parameters. The masses having a strong positive…

Coastal fish monitoring with multi-mesh gill nets and gill net series is carried out in eleven areas around the Baltic Sea. The purpose of the monitoring is to reveal population status and elucidate long-term trends of fish population and community development. Time series cover 9–20 years of annual monitoring, the last year being 2002. Significant increasing trends of perch and roach catches were observed in the archipelago region of the Sea of Åland and Archipelago Sea. A possible reason for these trends was ongoing coastal eutrophication. Significant trends with opposite directions appeared in two areas in the Gulf of Bothnia and two areas at the Swedish coast of the Baltic Proper. The Curonian Lagoon is severely affected by anthropogenic impact, structuring the local fish community. Indications of decreased eutrophication were noted in the Gulf of Riga. High fishing pressure during the 1990s in the West-Estonian archipelago and the following collapse of coastal fish stocks was apparent in the monitoring catches.

This study reviews sediment data obtained from the Baltic Sea from 1995–2003. Recent sediment accumulation rates (SAR) were estimated at 69 stations in the Baltic Sea from 99 sediment cores using concentration peaks of 137Cs and 239,240Pu as time markers of the years 1986 and 1963, respectively. SAR values varied widely between 60–6160 g m–2 yr–1. The highest SAR values were observed at stations in the northern part of the Bothnian Sea, river estuaries and the eastern part of the Gulf of Finland. Generally, the SAR (median) of stations in the Bothnian Sea was two times higher than values in the Gulf of Finland or the Bothnian Bay, and about seven times higher than in the Baltic Proper. A strong correlation was detected between the SAR and total 137Cs activities. The usability of estimation methods has been considered and, e.g., unstable sedimentation could limit the use of radionuclides in sediment dating and estimation of the SAR at stations in the Baltic Sea.

In terrestrial ecosystems, the amount and availability of water is one of the key factors affecting the net primary productivity and other biological processes of the system.At the SMEAR-II station, we have monitored the water balance of two adjacent micro-catchments since 1997.In this study, we report the long-term measurements of precipitation, throughfall, snow depth, soil water content, runoff and evapotranspiration and the annual water balances based on these measurements and discuss the uncertainties related to different measurements.The proportion of throughfall, evapotranspiration and runoff was 67%, 43% and 32% of the annual precipitation, respectively.The measured amounts of evapotranspiration and runoff were so small that the aim of closing the water balance of the studied system was not fully reached.The largest uncertainties are related to the evapotranspiration measurements and the determination of the actual surface area of the catchments used in the calculation of the runoff.

We measured surface water CO 2 concentrations continuously at three different depths to reveal the seasonal, daily and diel CO 2 dynamics of a steeply stratified pristine, spring-meromictic, humic lake during April 2005-October 2006. The lake was supersaturated with CO 2 most of the time and was a net source of CO 2 to the atmosphere. The stability of stratification and the depth of water column mixing strongly controlled the surface water CO 2 concentrations. Surface water concentrations as high as 195 μmol l -1 were measured when mixing extended to deep waters during spring ice breakup and autumn turnover. The concentrations were near the level of atmospheric equilibrium, about 15 μmol l -1 , during periods of high stability. The yearly CO 2 fluxes to the atmosphere were 3.7 and 2.5 mol m -2 in 2005 and 2006, respectively.

Reproduction of the northern Atlantic salmon population was studied to find out the effect of female size on quantity and quality of eggs. Total and relative fecundity of females were used for quantity measures. Size, energy and water contents of eggs and changes in them as well as mortality of eggs during the incubation were used as quality measures. The size of wild female Atlantic salmon had a positive effect on their total number of eggs and on the energy content of eggs. However, the effect of the female size on the egg size was weak and there was no correlation between the female size and relative fecundity. Overall, the benefit of body size was not only quantitative but also qualitative in reproduction success of the River Teno salmon.

evaluation of the emissions and uncertainties of Pm 2.5 originated from vehicular traffic and domestic wood combustion in Finland.Boreal Env.

The effects of nutrient load reductions on the biomass of N-fixing cyanobacteria were evaluated in the scale of the Gulf of Finland. The two analysed reduction scenarios were Finnish national agenda and the improvement of phosphorus removal in the present purification plants of St. Petersburg. The effects of load reduction scenarios were tested by using a 3D-ecosystem model with a horizontal resolution of 5 km. According to the results the Finnish national agenda cannot decrease the biomass of N-fixing cyanobacteria, but it seems to be able to reduce the total phytoplankton biomass in the coastal waters. The phosphorus reduction in St. Petersburg decreases the N-fixing cyanobacteria significantly in the central parts of the Gulf of Finland. Improvement of the phosphorus purification efficiency in the present sewage treatment plants offers us an opportunity to try to control the intensity of the toxic blooms of nitrogen-fixing cyanobacteria in the scale of the Gulf of Finland.

We measured the daily patterns of monoterpene emissions from Scots pine (Pinus sylvestris) trees in a boreal coniferous forest in August and September 2004, using an on-line chamber method combined with a proton-transfer-reaction mass spectrometry (PTR-MS) analyzer. The on-line measurements were made in two chambers with a one-year old shoot inside. Simultaneous measurements were performed for carbon dioxide (CO2) exchange, transpiration (H2O), exchange of trace gases (NOx, O3), photosynthetic photon flux density (PPFD), air temperature and relative humidity (RH). The composition of the monoterpene emission did not change during the measurement period, with [delta]3-carene and [alpha]-pinene being the dominant species. The total mono-terpene emission rate (per needle area) was on average 0.5 ng m–2 s–1, varied from non detectable to 2.1 ng m–2 s–1, and showed a typical diurnal pattern with afternoon maximum and nighttime minimum. The emission rates determined with this on-line chamber method were in agreement with results from a simultaneously used established adsorbent sampling…

The wind wave regime of Tallinn Bay, Gulf of Finland, is analysed with the use of a simplified method of long-term computations of wave fields based on a high-resolution nested WAM model and Kalbådagrund (1991–2000) wind data. The distributions of probabilities for wave heights, annual and seasonal mean wave heights, density of wave energy and its flux (wave power), and 1-year return wave heights as well as the wave field properties in extreme storms are computed. The mainland and surrounding islands together with numerous shallow areas shelter the bay from waves coming from the dominating strong wind directions. The average wave properties exhibit a significant seasonal and spatial variability. The highest waves occur in the vicinity of the Tallinn–Helsinki ship lane where the significant wave height exceeds 2 m each year and may reach 4 m in extreme NNW storms.

Based on Finnish lakes, meromixis is viewed from a paleolimnological perspective as a part of lake evolution. The study concludes that theoretical search of meromictic lakes is almost impossible, due to inconsistent and insufficient basic data and the complexity of meromixis as a phenomenon. An estimation of possible Finnish meromictic lakes turned out to be a few dozen. Meromictic lakes are more numerous than formerly expected, but still rare. Based on the present estimation, only one lake in 800 is truly meromictic. Their most probable geographical location, besides the coastal lakes, are the Salpausselkä end-moraine zone and the areas between the Salpausselkä zone, Ostrobothnia, the Kainuu Region, and the eastern border of Finland. Terminology concerning holomixis/meromixis is presently confusing and this study favors a strict use of the term meromictic and grouping complete and incomplete holomictic lakes as one group and true meromictic as another. The revised classification recognizes meromixis that has resulted from (1) flow/precipitation of saline water over freshwater or…

Methane (CH4) fluxes at the sediment–water interface were studied during summer in six lakes and two reservoirs in Finland. The oxygen penetration in the sediments of these boreal mesotrophic–hypereutrophic freshwater ecosystems varied from 0 to 8 mm, and the CH4 concentrations within the uppermost 10 cm from 17 to 51000 ppm(v). The diffusive methane fluxes to the overlying water column ranged from 0.44 to 105 mg m–2 d–1 and correlated negatively (R2 = 0.68) with the oxygen penetration in the sediment. This demonstrated that the CH4 concentration and the diffusive CH4 fluxes in the lake sediments are closely related to the O2 conditions, which regulate both CH4 production and CH4 oxidation in the sediment. The comparison between the diffusive CH4 fluxes at the sediment–water interface and CH4 fluxes at the water–air interface previously measured in situ in one lake and two reservoirs showed that the sediment CH4 fluxes poorly predict the CH4 release from the water surface to the atmosphere. This indicates that the CH4 oxidation in water column, advective transport of CH4 and CH4…

We measured the size distributions of positively and negatively charged particles in the size range 0.34-40 nm at the Finnish Antarctic research station Aboa from 14 December 2004 to 30 January 2005 with an Air Ion Spectrometer (AIS).Our focus was to study secondary particle formation in a clean environment.Therefore, we classified the 48 measurement days either as a particle formation event day, an undefined day or a non-event day.Approximately 23% of the days were particle formation event days, a fraction similar to that observed at a boreal forest site.The median diameter growth rates of negatively charged particles in size classes 1.3-3, 3-7 and 7-20 nm were 1.1, 1.5 and 4.3 nm h -1 , respectively, and somewhat lower for positively charged particles.Furthermore, we observed a clear positive correlation between the wind speed and cluster and intermediate ion concentrations, which suggests that ions were produced by friction processes in fast moving snow and ice crystals during the periods with strong winds.Cluster ions (diameter < 1.6 nm) were present during the whole measurement…

The Lagrangian trajectory model TRACMASS based on an Eulerian field of velocities (calculated using the Rossby Centre Ocean Model), combined with relevant statistical analysis, is used for the iden ...

In this study, we used a hot-air balloon as a platform for boundary layer particle and cluster measurements. We did altogether 11 flights during the springs of 2005 and 2006. During the spring of 2006, we observed five new-particle formation days. During all days, new-particle formation took place in the mixed boundary layer. During one of the days, we observed particle formation in the free troposphere, separate from that of the mixed layer. The observations showed that the concentration of freshly-formed 1.5-2 nm negative ions was several times higher than the concentration of positive ions. We also clearly observed that nucleation during one of the days, 13 March 2006, was a combination of neutral and ion-induced nucleation. During some of the days, particle growth stopped at around 3 nm, probably due to lack of condensable organic vapours. Simulations of boundary layer dynamics showed that particles are formed either throughout the mixed layer or in the lower part of it, not at the top of the layer.

A ten-year (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) research programme SUVI (Suomi-Viro) on the optics of Finnish and Estonian lakes has been completed.The objectives were to examine the light conditions, to map optically active substances (OAS), and to develop remote sensing methods.Altogether 14 Estonian and 7 Finnish lakes representing different types of water, from oligotrophic to hypertrophic and dystrophic were included.We performed extensive analyses of concentrations of three main OAS, light attenuation and Secchi depth.They varied among lakes and with seasons, but no systematic temporal change could be detected during the 10-year period.We studied the underwater light field using a spectrometer and two PAR quantum sensors, and elaborated three versions of optical classification of lake waters based on: (1) apparent optical properties and the amount of OAS, (2) irradiance reflectance spectra, and (3) light attenuation coefficient and the predominant OAS.We developed two models for determining the diffuse attenuation spectra of light, using data for…

Patterns in airborne pollen and other primary biological aerosol particles (PBaP), and their contribution to aerosol mass and number in a boreal forest.Boreal Env.Res.19 (suppl.B): 383-405.We studied variation in concentrations of airborne pollen and other particles of biological origin in a boreal forest in Finland during 2003Finland during -2004.The highest concentrations of pollen were observed in late spring and early summer, whereas the peak concentrations of other particles of biological origin (including e.g.fungal spores) occurred in August-September.Although the patterns in concentrations in 2003 and 2004 were similar, the concentration levels were significantly different between the years.The contribution of pollen and other particles of biological origin led to an increase in the measured particulate matter (PM) mass during the pollen season (mass of pollen and other particles of biological origin 5.9 and 0.4 µg m -3 , respectively, in respect to PM total mass of 9.9 µg m -3 ) but the effect on total particle number was negligible.The other particles of biological origin…

The standing biomass of a young Scots pine stand was measured at the SMEAR II experimental station in Hyytiälä, southern Finland. The stem volume was found to be 119 m3 ha–1, corresponding to 41450 kg ha–1 in stem biomass. The needle biomass was 5100 kg ha–1 and was constituted mainly by the two youngest needle age classes. The branch biomass was 9040 kg ha–1 and the root biomass 12 520 kg ha–1. The height of the first living branches was found to vary from 2.2 to 6.9 m, whereas the variation in tree height was between 4.1 and 14 m. The needle surface area was 3.9 m2 m–2 and the root length and surface area were 4180 m m–2 and 8.8 m2 m–2, respectively. More than half of the total fine root surface area was found in the upper 10 cm of the soil.

Finnish Meteorological Institute's air quality measuring station at Pallas, in northern Finland, has been part of the Global Atmosphere Watch programme of the World Meteorological Organization since 1994. Tropospheric air composition and meteorological measurements are made at four different locations. Measured components include greenhouse and reactive gases, volatile organic compounds, chemistry of precipitation and aerosols, radon, carbon dioxide flux, meteorological parameters and a number of different aerosol characteristics. Pallas has proven to be a good site for measuring continental background air. This paper gives a general overview of the Pallas GAW station measurement sites and methods, and extensive overview of the scientific results.

Ambient atmospheric concentrations of monoterpene compounds were measured above a boreal forest in Hyytiälä, Finland during 2000-2007.For most of the time, two samples per week were collected, although there are some gaps in the data due to analytical or other issues.The monoterpene concentrations reached their maximum in summer, although they were found to be quite high also during winter.The main compounds found during winter were α-pinene, Δ 3 -carene, β-pinene and camphene.In summer 1,8-cineol and sabinene were also present in the samples.The concentrations of α-pinene, β-pinene/myrcene, camphene, Δ 3 -carene increased during the measurement period both in winter and in summer.This increase cannot be explained by meteorological conditions.The possible explanations could be human activities in the vicinity of the sampling site in addition to forest growth.The seasonal cycles of daytime concentrations were found to follow emission fl uxes modeled using a simple temperature dependent parameterisation.The measured monoterpene concentrations were used, together with emission rate…

Extreme events can often be ecologically more relevant than fluctuations in the mean climate. We studied the effects of an exceptionally rainy period in 2000 on 13 physical and chemical variables and on the phytoplankton biomass and composition in Lake Mälaren, the third largest lake in Sweden. The rainy period caused a distinct increase in the chemical loading, in particular the loading of organic carbon, into Lake Mälaren. As a consequence water color, measured as light absorption of filtered water, was up to 3.4 times higher in 2001 than ever recorded since 1965. In addition, reactive silica concentrations doubled, particle concentrations were the highest and conductivity was the lowest registered. The changes in physical and chemical conditions of Lake Mälaren in 2001 showed temporal and spatial differences depending on runoff processes in the catchment, water residence times and the type of variable. It is suggested that especially the increase in water color was responsible for the observed doubling in the cryptophycean biomass in Lake Mälaren in May 2001. The increase in…

The effects of climate change on water resources in Finland have been evaluated by conceptual watershed models. The central SILMU scenario is used as a climate change approximation for the future. The evaluated water balance terms are areal corrected precipitation, evapotranspiration, lake evaporation, water equivalent of snow, soil moisture, groundwater and runoff. Changes in the mean values and seasonal distributions of river discharges and lake water levels are also presented. The precipitation and temperature increases assumed by the central SILMU-scenario will not essentially affect annual water balance, but will strongly change the seasonal distribution of runoff and other water balance terms. Snow cover will diminish or almost vanish and its duration will be shortened by one to four months in different scenario runs due to warming. The winters will become wetter and snow-free due to increased precipitation and frequent thawing periods. Spring floods will diminish or vanish and winter floods will occur instead. The summers will become drier due to the longer summer season and…

Potential reasons for the drastic intensification and step-like nature of coastal erosion in the Neva Bay area (to the east of the cape Peschany―Lebyazhye line), the easternmost part of the Gulf of Finland, are analysed based on field observations and hydrometeorogical data from adjacent areas. Beaches in this area consist of easily erodible Quaternary deposits that evolve under overall sediment deficit and are relatively vulnerable with respect to changes in the external forcing factors. It is demonstrated that the most extreme erosion events occur when high waves excited by long-lasting western or south-western storms attack the coast during very high storm surges in the absence of stable sea ice. Since 2004 the frequency of occurrence of such combinations has increased mostly owing to, late freezing of the bay and an increase in the number and severity of extreme erosion events in the future is likely. The coasts are also under gradually increasing anthropogenic pressure. Submarine mining operations in the nearshore and construction of large-scale coastal engineering structures…

Only little is known about the long-term carbon dynamics related to peatland restoration. We studied CO 2 and CH 4 dynamics of spontaneously regenerated peat trenches five decades after peat harvesting had ceased. We used non-linear regression models and interpolation for simulating gas exchange of four regenerating plant communities during two growing seasons and one winter. The studied communities all acted as seasonal (June-September) sinks of CO 2 between 14 and 118 g C m -2 , while the emissions of CH 4 ranged from -4.9 to -28.8 g C m -2 . When the winter time losses of carbon and the estimated leaching were subtracted, the balance was very low or negative: between -67 and 31 g C m- 2 . The low or even negative annual carbon balance in all communities may suggest a decrease in carbon sink strength in the advanced regeneration after the previously observed strong sink in the first regeneration stages caused by mass colonization by Eriophorum.

influence of taxonomic resolution and data transformation on biotic matrix concordance and assemblage-environment relationships in stream macroinvertebrates.

carbon dioxide exchange above a 30-year-old scots pine plantation established on organic-soil cropland

aquatic plant biodiversity at high latitudes: patterns of richness and rarity in Finnish freshwater macrophytes.

Residential wood combustion is a significant particulate emission source in many European countries. Especially for fine particle emissions in wood combustions, the lacking knowledge of emission factors (F E ) makes assessment of their contribution to ambient concentrations difficult. One reason for the discrepancy between modeled and measured contributions is many variables involved in combustion process. In this study, the fine particulate matter (PM) emissions coming from batch combustion of birch wood in a small masonry heater were investigated. The experiments were carried out in the specified conditions (normal and smouldering combustion, NC and SC, respectively). To enable various chemical analytical techniques, two sampling combinations for PM 2.5 (particle diameter < 2.5 μm), and size-segregated sampling were used. The samples were analyzed for gravimetric mass, major ions, monosaccharide anhydrides (MA, including levoglucosan, galactosan and mannosan), trace elements, elemental carbon (EC) and water-insoluble and -soluble particulate organic matter (WISPOM and WSPOM,…

The aim of the paper is to analyse the sea level variability at the Lithuanian coast during the last 100 years using all data available in Lithuania. The analysis, based on sea level data of the Klaipeda Strait for 1898–2002, clearly shows that the long-term sea level increased by about 13.9 cm. Furthermore, it is remarkable that the increase is not found to be linear during the study period. Only a negligible increase is found at every Lithuanian tide gauge until World War II. Starting from the middle of the last century the increase in sea level is more pronounced having a rate of about 3 mm per year since the 1970s. This rise leads to manifold practical problems concerning activities in the coastal areas. The water rise will intensify the intrusion of salty water into the Curonian Lagoon slowly changing the ecosystems in its northern part. The reasons behind this rise are related to enhanced and more frequent advection of warm and moist maritime air masses during the cold season (October–March). This is coupled with intensified air flow from the west with increasing air…

The dependence of sea level on past and future climatological conditions is investigated in nearly tideless semi-enclosed sub-basins of the Baltic Sea using trend analysis of the tide gauge data for the period of 1924–2003 and hydrodynamic modelling. The results suggest that in addition to the effect of eustatic rise in mean sea level and its partial compensation by isostatic land uplift, the water level has risen by up to 6 cm near the Estonian coast during the last fifty years, probably due to changes in wind climate. The sea-level increase was concentrated in the period from November to March. It is in good correlation with increasing trends in local storminess and in higher intensity of westerlies, as described by AO and NAO indices. For the future sea level, a set of sensitivity and scenario runs considering possible future changes in wind climate was performed using a 2D hydrodynamic model with a 1-km grid-step. The scenario runs show that if the intensity of westerlies continues to grow (with less than 20% annual mean wind speed increase) the local annual mean sea level rise…

The forest soil carbon sink is of potentially great monetary value under subsequent climate conventions, but the costs of reliable monitoring have never been analysed.Our study aimed at evaluating (1) costs and precision of varied sampling intensities at the plot level, (2) sample size, and (3) costs needed to detect a change in soil carbon at the national scale.Organic layer carbon measurements cost 520 euros per plot if 10 samples are analysed.At plot scale, the precision obtained with such sampling allows detection of a large change > 860 g C m -2 .At the national scale, two measurement rounds on a minimum of 3000 plots are needed to detect an expected change of 11 g C m -2 yr -1 in the organic layer of upland forest soils with a 10-year sampling interval.Measuring such a network once costs approximately 4 million euros, which is about 8% of the value of the annual CO 2 sequestration of 2.57 ¥ 10 6 t CO 2 of upland forest soils in Finland.

The data from observations made in the Hyytiälä background station over the period 1997–2003 were analyzed in order to investigate the possible links between physical, chemical and meteorological parameters for event and nonevent days during different seasons. The seasonal patterns of average trace gas (O3, H2O, NOx = NO + NO2, SO2) concentrations, UV-A irradiation intensity, temperature, relative humidity and condensation sink were established and used for evaluating their influence on the seasonal dependence of the formation and growth rates of particles in the nucleation mode. For the forest region at Hyytiälä, an estimate was made on the contribution of the oxidation products of SO2 and volatile organic compounds (VOCs) by O3 and OH to the formation and growth of the nucleation mode particles. The condensation sink was shown to play a crucial role in the chemical dynamics of gaseous precursors and aerosol particles. The variability of the sink was attributed mainly to the humidification of the pre-existing aerosol particle population, depending thus strongly on the relative…

We report the results on eddy covariance measurements of net ecosystem exchange (NEE) and accompanying latent and sensible heat fluxes for 44 months in boreal Scots pine forest (southern Finland). We analysed the temperature dependence of ecosystem respiration and PPFD (photosynthetic photon flux density) dependence of daytime CO2 exchange and calculated the annual carbon budget filling the gaps in data series with the temperature and light dependences. The estimated annual balances of the NEE's were –234 g C m–2, –262 g C m–2 and –191 g C m–2 in 1997, 1998 and 1999, respectively. We calculated also NEE's for every possible 365-day periods included in the data series and the maximum and minimum of such NEE's were –165 g C m–2 and –304 g C m–2. The growing season started around 28 April, 16 April and 25 March in 1997, 1998 and 1999, respectively. The maximum light saturated CO2 uptake rate reached the value of 12 umol m–2 s–1 gradually by the end of June. In autumn, the uptake did not decline gradually but ceased rapidly round the beginning of November. The non-growing season…

Natural disturbances are important for forest ecosystem dynamics and maintenance of biodiversity.In the boreal forest, large-scale disturbances such as wildfires and windstorms have been emphasized, while disturbance agents acting at smaller scales have received less attention.Especially in Europe beavers have long been neglected as forest disturbance agents because they were extirpated from most of their range centuries ago.However, now they are returning to many parts of their former distribution range.As a disturbance agent, beaver plays two roles: of an ecosystem engineer and of a herbivore.The engineering impact is realized through dam construction resulting in a transformation of an originally terrestrial ecosystem into an aquatic one.As herbivores, beavers affect stand structure and tree species composition by preferring deciduous trees over coniferous ones.After abandonment, a beaver pond gradually turns into a terrestrial habitat again.At well-drained sites, forest will return in due course, first dominated by deciduous trees.At poorly drained sites, moistness of beaver…

Climatic change impact studies are among the most complicated and uncertain environmental assessments scientists have ever faced. Not only are possible scenarios on key changes and impacts needed, but also estimates of their probabilities, which are of particular relevance to policy making. In modeling, the key uncertainties lie in inaccuracies and errors in parameters, and above all (but often not fully discussed) in assumed causalities (model structure). In the present study, the views of eight Finnish experts on interactions between climatic and aquatic systems were analyzed. They were asked to assess the states of 24 key variables in the climate-water system in southern Finland, using subjective probability distributions and the causalities between those variables. The methodological approach used was based on Bayesian belief networks. The highest uncertainties were seen in the changes of floods, water pH and oxygen concentrations, problems to constructions, and the recreational value of watersheds. Positive impacts can be expected on transportation and hydropower production.…

Evaluation of changes in Baltic Sea phytoplankton communities has been hampered by a lack of quantitative long-term data. We investigated changes in biomass of summer (June–September) phytoplankton ...

It is very important to detect changes in forest productivity due to the global change on a large scale. In this work, the evolution of the vegetation in the Komi Republic (northwestern Russia) from 1982 to 2001 was analyzed using NOAA AVHRR PAL time series. A statistically significant correlation (adjusted r2 = 0.44–0.59) between Normalized Difference Vegetation Index (NDVI) data and tree ring width (261 living trees) was identified for the territory of the Komi Republic. The increased site productivity reflected an increase of integrated NDVI values from June to August. This allows NDVI to be used as a proxy for estimation of forest growth trends for the recent decades. A positive and significant trend in NDVI data was identified from 1982 to 2001, coinciding with an increase in site productivity in the study area. The decrease in precipitations coincided with an increase in site productivity (highest r2 was 0.71). The increase in productivity reflected in NDVI data is maximal on the sites with increased temperature and decreased precipitations. In the Komi Republic the…

The effect of boreal forest on the Earth's energy budget was estimated in field conditions in Hyytiälä, southern Finland. The indirect aerosol effect due to new particle formation, the effect of forest carbon sequestration and the effect of forestation- or deforestation-related albedo change were investigated. The young, fast-growing boreal forest was estimated to be a relatively significant carbon sink and an important aerosol source, and thus the effect on the Earth's energy budget was seen to be negative. The estimated values (reported as annually averaged energy budget perturbations per square meter of forest) were –36 W m–2 due to the carbon sink, +10 W m–2 due to the albedo effect and between –5 and –14 W m–2 due to the aerosol effect. However, the values are uncertain.

Fossil midge larvae (Diptera: chironomidae) as quantitative indicators of late-winter hypolimnetic oxygen in southern Finland: a calibration model, case studies and potentialities.Boreal Env.Res.15: 1-18.We examined the relationship between fossil chironomid assemblages and environmental variables in 30 lakes in southern Finland with particular attention to hypolimnetic oxygen.Ordination techniques (DCA, CCAs) and Monte Carlo permutation tests were used to identify the most important parameters controlling the chironomid distributions.Based on the λ 1 :λ 2 ratios of the variables, the greatest potential for quantitative inferences was with hypolimnetic oxygen (λ 1 :λ 2 = 0.767).Therefore, inference models for past late-winter hypolimnetic oxygen were developed using weighted-averaging partial least squares (WA-PLS) techniques.The best model used one WA-PLS component, with a cross-validated coefficient of determination (r 2 jack ) of 0.72 and a root-mean-squared error of prediction (RMSEP) of 2.351 mg l -1 .The model was tested on two short-core sediment sequences.The results…

Phytoplankton is one of the biological quality elements of the Water Framework Directive of European Union for ecological classification of surface waters included.The reliability and comparability of phytoplankton data is, therefore, essential in assessment of the classification.The recently published standard for phytoplankton analysis based on the Utermöhl technique supports stringent demands for comparability of data.We tested the comparability of phytoplankton analyses (Utermöhl method) between professional and non-professional analysts.The coefficient of variation was highly variable, 10%-42% for professionals and 8%-57% for non-professionals.Elimination of the error caused by subsampling and the increase in the minimum number of enumerated units decreased the CV especially within professionals.CV was smaller (4%-19%) when samples were counted by one person.In order to minimize the variability caused by differences between subsamples, new methods for comparison testing both for technical enumeration and for species identification should be developed.

vartiainen, e., Kulmala, m., ehn, m., hirsikko, a., Junninen, h., Petäjä, t., sogacheva, l., Kuokka, s., hillamo, r., skorokhod, a

low survival of hatcheryreleased atlantic salmon smolts during initial river and fjord migration

tree stand volume as a scalar for methane fluxes in

The aim of the study was to test the possibility of using the Normalized Difference Vegetation Index (NDVI) for distinguishing between differently managed mountain grassland sites surrounded by boreal forests.The NDVI was assessed under field conditions in three differently managed meadows (mown, mulched, unmanaged), at an altitude of 1150 to 1170 m in the Bohemian Forest Mts.The mowing and mulching were applied to the respective plots in mid-July and three successive NDVI/aboveground biomass assessments were made before and two after the application of the treatments.The presence of litter, expressed by the green ratio index (GR), strongly affected the reflectance of the grassland canopy.The linear relationships between green biomass and NDVI were statistically significant for all treatments only during the period before the application of the treatments.It was only in the unmanaged plot that a statistically significant linear relationship between NDVI and GR was recorded.

A size-segregated chemical composition of atmospheric aerosols was investigated in May 2004 at the SMEAR II station, southern Finland. Aerosols were collected using two 12-stage low pressure impactors (SDI) and two virtual impactors (VI). The samples were analyzed for mass, inorganic ions and organic (OC) and elemental carbon (EC). By comparing the gravimetric mass and the results from the chemical analyses, a chemical mass closure was constructed. In addition to the impactors an Electrical Low Pressure Impactor (ELPI), Differential Mobility Particle Sizer (DMPS) and Aerodynamic Particle Sizer (APS) were used to measure the mass size distribution continuously. The chemical composition of fine particles (particle diameter %X 1 um) was very similar over the whole measurement campaign with 40% of mass composed of ammonium sulfate, 35% of OC and 5% of EC. In the submicron range the chemical mass closure of the collected samples was reached within a few percent on average. The chemical mass to gravimetric mass ratio was 0.98 ± 0.10 and 1.05 ± 0.13 (average ± S.D.) for the VI and SDI,…

Upwelling characteristics derived from satellite sea surface temperature data in the Gulf of Finland, Baltic sea.Boreal Env.

long term changes in the Baltic sea phytoplankton community