ISSN 1239-6095
© Boreal Environment Research 2004

Contents of Volume 9 Number 1

Andrejev, O., Myrberg, K., Alenius, P. & Lundberg, P. A. 2004: Mean circulation and water exchange in the Gulf of Finland — a study based on three-dimensional modelling. Boreal Env. Res. 9: 1–16.
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Jones, R. I. & Grey, J. 2004: Stable isotope analysis of chironomid larvae from some Finnish forest lakes indicates dietary contribution from biogenic methane. Boreal Env. Res. 9: 17–23.
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Trei, T. & Pall, P. 2004: Macroflora in the watercourses of Saaremaa Island (Estonia). Boreal Env. Res. 9: 25–35.
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Hakala, A. 2004: Meromixis as a part of lake evolution; observations and a revised classification of true meromictic lakes in Finland. Boreal Env. Res. 9: 37–53.
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Heinimaa, S. & Heinimaa, P. 2004: Effect of the female size on egg quality and fecundity of the wild Atlantic salmon in the sub-arctic River Teno. Boreal Env. Res. 9: 55–62.
Abstract
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Kulmala, M., Boy, M., Suni, T., Gaman, A., Raivonen, M., Aaltonen, V., Adler, H., Anttila, T., Fiedler, V., Grönholm, T., Hellén, H., Herrmann, E., Jalonen, R., Jussila, M., Komppula, M., Kosmale, M., Plauskaite, K., Reis, R., Savola, N., Soini, P., Virtanen, S., Aalto, P., Dal Maso, M., Hakola, H., Keronen, P., Vehkamäki, H., Rannik, Ü., Lehtinen, K. E. J. & Hari, P. 2004: Aerosols in boreal forest: wintertime relations between formation events and bio-geo-chemical activity. Boreal Env. Res. 9: 63–74.
Abstract
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Pohjola, M. A, Rantamäki, M., Kukkonen, J., Karppinen, A. & Berge, E. 2004: Meteorological evaluation of a severe air pollution episode in Helsinki on 27–29 December 1995. Boreal Env. Res. 9: 75–87.
Abstract
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Andrejev, O., Myrberg, K., Alenius, P. & Lundberg, P. A. 2004: Mean circulation and water exchange in the Gulf of Finland — a study based on three-dimensional modelling. Boreal Env. Res. 9: 1–16.

A three-dimensional baroclinic prognostic model has been applied to study the mean circulation and its persistency as well as the water exchange in the Gulf of Finland. A five-year simulation for 1987–1992 was carried out using a nested grid approach, where a high-resolution sub-model of the Gulf of Finland was forced at the open boundary by a larger-scale Baltic Sea model. Realistic meteorological forcing for the period under study was used. The overall results of the investigation showed that the mean circulation pattern was complex with numerous meso-scale eddies, although a cyclonic mean circulation generally is discernible. The mean surface circulation of the Gulf was found to take place in the form of a strong outflow adjacent to the Finnish coast compensated for by an inflow at the Estonian coast, a circulation which is highly dependent on depth. The outflow on the northern side of the Gulf proved to be a distinct feature with a persistency ranging between 50% and 80%. The water exchange between the Gulf and the Baltic Proper appears to be stronger than previously estimated. It was found that ordinary budget estimates of water exchange (based on calculating the amount of in- and out-flowing water) do not give much relevant information concerning the Baltic Sea Proper–Gulf water exchange since these straightforward estimates do not reflect the internal dynamics of the Gulf of Finland.
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Jones, R. I. & Grey, J. 2004: Stable isotope analysis of chironomid larvae from some Finnish forest lakes indicates dietary contribution from biogenic methane. Boreal Env. Res. 9: 17–23.

Larval chironomids (mostly Chironomus tenuistylus) were collected from the sediments of five small forest lakes in southern Finland during summer 2002. Carbon and nitrogen isotope ratios of larvae were determined by isotope ratio mass spectrometry. Isotope ratio variability among 23 individuals from one lake was appreciable, with [ta13C showing a range spanning 1.6% and [ta15N values a range spanning 5.6%. Between the lakes, larvae showed considerable variation in [ta13C with values as low as –55%. [ta15N values were strongly correlated with [ta13C values. The 13C-depletion found in the benthic chironomid larvae correlated with that found previously in zooplankton from the same lakes. It is argued that the low [ta13C values are most likely attributable to incorporation of carbon from biogenic methane, and that methane production can therefore make an important contribution to benthic as well as to pelagic food webs in these small forest lakes.
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Trei, T. & Pall, P. 2004: Macroflora in the watercourses of Saaremaa Island (Estonia). Boreal Env. Res. 9: 25–35.

The study focused on 40 reaches of 29 short narrow shallow watercourses on Saaremaa Island. The floristic list covers 68 taxa of vascular plants, including 14 species of true or obligate water plants, 18 taxa of amphibious plants, and 36 taxa of terrestrial plants. The article presents differences in the frequency of vascular plants between the watercourses of Saaremaa and mainland Estonia. Three taxa of macroalgae were new to Estonia. Ranunculus aquatilis, Berula erecta, and Alisma plantago-aquatica preferred a higher content of nitrogen compounds. However, Lemna minor, Veronica anagallis-aquatica, and Agrostis stolonifera var. prorepens preferred a higher content of phosphorous compounds. Cladophora rivularis preferred both higher nitrogen and phosphorous compounds in water. Potamogeton natans and Equisetum fluviatile preferred softer sediments, and Ulothrix zonata preferred relatively low pH values.
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Hakala, A. 2004: Meromixis as a part of lake evolution; observations and a revised classification of true meromictic lakes in Finland. Boreal Env. Res. 9: 37–53.

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 freshwater over saline water, (2) superficial diffuse nutrient load and/or turbidity currents from the catchment, (3) subsurface inflow of groundwater, (4) inadequate mixing due to the lake morphology and surrounding topography.
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Heinimaa, S. & Heinimaa, P. 2004: Effect of the female size on egg quality and fecundity of the wild Atlantic salmon in the sub-arctic River Teno. Boreal Env. Res. 9: 55–62.

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.
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Kulmala, M., Boy, M., Suni, T., Gaman, A., Raivonen, M., Aaltonen, V., Adler, H., Anttila, T., Fiedler, V., Grönholm, T., Hellén, H., Herrmann, E., Jalonen, R., Jussila, M., Komppula, M., Kosmale, M., Plauskaite, K., Reis, R., Savola, N., Soini, P., Virtanen, S., Aalto, P., Dal Maso, M., Hakola, H., Keronen, P., Vehkamäki, H., Rannik, Ü., Lehtinen, K. E. J. & Hari, P. 2004: Aerosols in boreal forest: wintertime relations between formation events and bio-geo-chemical activity. Boreal Env. Res. 9: 63–74.

We studied wintertime aerosol formation and subsequent particle growth events that have been frequently observed in ambient air at a boreal forest site (SMEAR II station) in southern Finland. Aerosol size distributions, gas concentrations, biological activity and meteorological parameters have been measured at the site continuously since 1996. An important observation, based on flux measurements, was that all particle formation events were connected with either increased water evapo-transpiration or carbon dioxide uptake by the forest. However, increased H2O or CO2 fluxes did also occur on days without aerosol formation events, but these occasions were connected to cloudy or polluted days with high pre-existing aerosol concentrations. Thus, our overall conclusion is that in order for an aerosol formation event to occur, some ecological or bio-geo-chemical activity is needed. During wintertime, this activity seems to be mostly related to snow–atmosphere interactions.
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Pohjola, M. A, Rantamäki, M., Kukkonen, J., Karppinen, A. & Berge, E. 2004: Meteorological evaluation of a severe air pollution episode in Helsinki on 27–29 December 1995. Boreal Env. Res. 9: 75–87.

This paper describes an evaluation and meteorological analysis of a severe air quality episode that occurred in the Helsinki Metropolitan Area during 27–29 December 1995. The pollutants originated predominantly from local sources. The episode was formed in anticyclonic high pressure conditions that lead to low wind speeds and the formation of an extremely strong ground-based radiation inversion. We utilised the 24 hourly forecasts of the Finnish version of the numerical weather forecasting model HIRLAM (High Resolution Limited Area Model, operational from 1999 to 2003). The HIRLAM model under-predicted both the inversion strengths (°C) and inversion temperature gradients (°C m–1), compared with the corresponding measured data. We also compared the temperature profiles predicted by HIRLAM with those predicted by the non-hydrostatic meteorological model MM5. The pollutant concentrations during the episode have been predicted using an urban dispersion modelling system, and evaluated against measured data.
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