ISSN 1239-6095
© Boreal Environment Research 2007

Contents of Volume 12 Number 5

Damski, J., Thölix, L., Backman, L., Taalas, P. & Kulmala, M. 2007: FinROSE — middle atmospheric chemistry transport model. Boreal Env. Res. 12: 535–550.
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Pilkaityte, R. & Razinkovas, A. 2007: Seasonal changes in phytoplankton composition and nutrient limitation in a shallow Baltic lagoon. Boreal Env. Res. 12: 551–559.
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Vuorio, K., Lepistö, L. & Holopainen, A.-L. 2007: Intercalibrations of freshwater phytoplankton analyses. Boreal Env. Res. 12: 561–569.
Abstract
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Niemi, J. & Raateland, A. 2007: River water quality in the Finnish Eurowaternet. Boreal Env. Res. 12: 571–584.
Abstract
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Elo, P. A.-R. 2007: The energy balance and vertical thermal structure of two small boreal lakes in summer. Boreal Env. Res. 12: 585–600.
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Väänänen, R., Kenttämies, K., Nieminen, M. & Ilvesniemi, H. 2007: Phosphorus retention properties of forest humus layer in buffer zones and clear-cut areas in southern Finland. Boreal Env. Res. 12: 601–609.
Abstract
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Saarse, L. & Niinemets, E. 2007: Environmental changes in SE Estonia during the last 700 years. Boreal Env. Res. 12: 611–621.
Abstract
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Damski, J., Thölix, L., Backman, L., Taalas, P. & Kulmala, M. 2007: FinROSE — middle atmospheric chemistry transport model. Boreal Env. Res. 12: 535–550.

In this paper we describe the development and performance of a three-dimensional global middle atmospheric chemistry transport model FinROSE. The FinROSE chemistry transport model includes a numerical scheme for stratospheric chemistry with parameterizations for heterogeneous processing on polar stratospheric clouds (PSC) and on liquid binary aerosols together with a parameterisation of large nitric acid trihydrate particles (i.e. NAT-rocks) and PSC sedimentation. The total number of trace species in the model is 34 and the total number of gas-phase reactions, photodissociation processes and heterogeneous reactions is about 150. The model is forced by external wind and temperature fields. The simulations are normally performed in a 5° x 10° (lat. x long.) grid from the surface up to around 0.1 hPa, with a vertical resolution of ca. 1.5 km in the stratosphere. Long-term simulations (40 to 50 years) have been done using winds and temperatures from ECMWF ERA40 analyses. The performance of the model in describing the stratospheric composition and chemistry is shown and evaluated in this paper. In general, the FinROSE results show a good comparison with measured total ozone. Also the timing, the depth and the deepening of the Antarctic ozone hole, and the responsible processes are captured well in the model simulations.
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Pilkaityte, R. & Razinkovas, A. 2007: Seasonal changes in phytoplankton composition and nutrient limitation in a shallow Baltic lagoon. Boreal Env. Res. 12: 551–559.

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 controlled mostly by the ambient physical factors. However, seasonal variation in nutrient concentrations could shape the phytoplankton community and, in combination with physical factors, force the seasonal succession.
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Vuorio, K., Lepistö, L. & Holopainen, A.-L. 2007: Intercalibrations of freshwater phytoplankton analyses. Boreal Env. Res. 12: 561–569.

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.
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Niemi, J. & Raateland, A. 2007: River water quality in the Finnish Eurowaternet. Boreal Env. Res. 12: 571–584.

The Finnish Eurowaternet monitoring network includes about 200 river sites that are among the northernmost in the European Eurowaternet monitoring network. Their water quality was investigated using the medians of physico-chemical parameters (total phosphorus, total nitrogen, dissolved oxygen saturation percentage, pH, alkalinity, chemical oxygen demand, colour, electrical conductivity, total suspended solids, turbidity), hygienic indicator bacteria and trace metals (iron, zinc, nickel, chromium, copper, cadmium, arsenic, lead and mercury) calculated for the period 1998–2002. The river water quality was poorest in the south, improved towards the north and was best above the Arctic Circle. In addition it varied in the east–west direction being poorest in the west and best in the east. In the south population density is higher, there is more industry, arable land, agriculture and animal husbandry, which explain water quality differences. On a European scale the majority of the Finnish rivers, particularly those in the north, are rather unpolluted.
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Elo, P. A.-R. 2007: The energy balance and vertical thermal structure of two small boreal lakes in summer. Boreal Env. Res. 12: 585–600.

Two small lakes in Sweden were studied using one-dimensional approach. Their summer energy balance and temperature structure were considered based on measurements and on modelling on different scales. Tämnaren is a vertically-mixed lake because it is very shallow and has a large surface area. Råksjö is small, sheltered and typically stratified during summer. Model adjustments and calibrations were made using detailed micrometeorological input data, considering areal variations. Components of the heat balance were determined in order to solve for water temperature and heat exchange. Absorption of energy inside water was determined on the basis of measurements. The vertical temperature structure was solved using a k[epsilon]-model. The results clearly show that sheltering caused by shores must be taken into account. Modifying the wind speed has a strong effect on temperature, especially at greater depths, and on heat balance. An isothermal box lake model, the SLAB model, was used with the same input. Surface temperature is strongly influenced by meteorological conditions, and both models solve it very similarly. Diurnal temperature variations, which can be as much as several degrees, are lost with the SLAB model. The PROBE model is able to solve these variations and the vertical temperature profile. However, if the important boundary effects are not taken into account, neither can be solved satisfactorily. Point measurements gave a residual of –53 W m–2 for Tämnaren, and –42 W m–2 for Råksjö. When wind was reduced to 80% for Tämnaren, and 60% for Råksjö to account for the net areal effect, the residuals were 0 and –1 W m–2 for the lakes. Temperature profiles were also satisfactorily solved.
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Väänänen, R., Kenttämies, K., Nieminen, M. & Ilvesniemi, H. 2007: Phosphorus retention properties of forest humus layer in buffer zones and clear-cut areas in southern Finland. Boreal Env. Res. 12: 601–609.

Hydrological losses of phosphorus (P) from forested areas have been reported to increase after harvesting operations. An efficient method of decreasing P losses has been to leave unmanaged buffer zones along forest brooks, streams and lakes. However, the processes controlling P retention by buffer zones are still not fully understood. To assess the importance of forest humus layer in P retention a small-scale survey was carried out at three buffer zones and adjoining clear-cut areas in southern Finland. In general, the humus layer in the buffer zones adsorbed more P than in clear-cut areas and the P adsorption was strongly related to the contents of oxalate extractable iron and aluminium. However, there were indications that the P retention capacity of the humus may decrease with the length of time the clear-cut area or buffer zone has been under the impacts of clear-cutting. There may be significant seasonal changes in humus P retention, but further studies are needed for a critical evaluation of the changes in humus P adsorption between seasons and years. Nevertheless, when compared with the increase in P release after harvest in a boreal forest, the maximum P retention capacity of the humus layer was small. Therefore, the role of the forest humus layer in P retention in clear-cut areas and buffer zones may be insignificant.
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Saarse, L. & Niinemets, E. 2007: Environmental changes in SE Estonia during the last 700 years. Boreal Env. Res. 12: 611–621.

Sediment sequences retrieved from three lakes in southeastern Estonia were analysed for lithology, pollen stratigraphy and high-resolution loss-on-ignition (LOI) to study the environmental changes during the last 700 years. Age control was provided by varve counts, AMS 14C and 210Pb dates complemented by 137Cs and 241Am measurements, which confirmed the annual character of the sediments. LOI results displayed several periods with reduced values of organic matter and increased mineral matter fluxes. Organic production in the lakes and on the catchment was sensitive to climate change and human impact, while mineral load was mostly determined by external factors, which promoted soil erosion and influx into the lake. During the last 700 years in the environmental history of SE Estonia the three main phases were distinguished: low land-use phase between AD 1300 and 1750, extensive arable farming phase at AD 1750 and 1940 and diminished arable farming phase since AD 1940. This study showed, that the formation and development of the landscape in SE Estonia during the last 700 years was characterized by rapid changes in vegetation and lake sediment composition determined mostly by human impact, certain historic processes and climate change.
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