Sarkkola, S., Nieminen, M., Koivusalo, H., Laurén, A., Kortelainen, P., Mattsson, T., Palviainen, M., Piirainen, S., Starr, M. & Finér, L. 2012: Trends in concentrations and export of nitrogen in boreal forest streams. Boreal Env. Res. 17: 85–101.
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Mousavi, S. K. & Amundsen, P.-A. 2012: Seasonal variations in the profundal Chironomidae (Diptera) assemblage of a subarctic lake. Boreal Env. Res. 17: 102–112.
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Nõlvak, H., Sildvee, T., Kriipsalu, M. & Truu, J. 2012: Application of microbial community profiling and functional gene detection for assessment of natural attenuation of petroleum hydrocarbons in boreal subsurface. Boreal Env. Res. 17: 113–127.
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Ruoho-Airola, T. 2012: Comparison of atmospheric concentrations of sulphur and nitrogen compounds, chloride and base cations at Ähtäri and Hyytiälä, Finland. Boreal Env. Res. 17: 128–138.
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Huusko, A. & Hyvärinen, P. 2012: Atlantic salmon abundance and size track climate regimes in the Baltic Sea. Boreal Env. Res. 17: 139–149.
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Kriauciuniene, J., Meilutyte-Barauskiene, D., Reihan, A., Koltsova, T., Lizuma, L. & Sarauskiene, D. 2012: Variability in temperature, precipitation and river discharge in the Baltic States. Boreal Env. Res. 17: 150–162.
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Sarkkola, S., Nieminen, M., Koivusalo, H., Laurén, A., Kortelainen, P., Mattsson, T., Palviainen, M., Piirainen, S., Starr, M. & Finér, L. 2012: Trends in concentrations and export of nitrogen in boreal forest streams. Boreal Env. Res. 17: 85–101.

Temporal trends in inorganic and organic nitrogen (N) export in the stream water between 1979 and 2006 were studied in eight forested headwater catchments in eastern Finland, where an increasing air-temperature trend and a decreasing N-deposition trend has been observed since the 1980s. The Seasonal Kendall test was conducted to study if the stream water N concentrations have changed concurrently and a mixed model regression analysis was used to study which catchment characteristics and hydrometeorological variables were related to the variation in stream water N. The annual concentrations of total organic N (TON) increased at two catchments and the concentrations of nitrate (NO₃-N) and ammonium (NH₄-N) decreased at three and four catchments, respectively. The main factor explaining variation in concentrations and export of N was percentage of peatlands in a catchment. The NH₄-N concentrations were also related to the N deposition, and the exports of NO₃, NH₄, and TON to precipitation. Quantitative changes in both the N concentrations and exports were small. The results suggested relatively small changes in the N concentrations and exports between 1979 and 2006, most probably because the effects of increased air and stream water temperatures largely have been concealed behind the concurrent decrease in N deposition.

Mousavi, S. K. & Amundsen, P.-A. 2012: Seasonal variations in the profundal Chironomidae (Diptera) assemblage of a subarctic lake. Boreal Env. Res. 17: 102–112.

Zoobenthos samples were collected over a 12-month period in the profundal zone of the subarctic Fjellfrøsvatn, a lake in northern Norway. Chironomid larvae numerically dominated the profundal zoobenthos and their mean density decreased with increasing depth. Procladius (Holotanypus) sp. A, Mesocricotopus thienemanni, Psectrocladius (Mesopsectrocladius) sp. and Heterotrissocladius subpilosus exhibited the highest densities at the depth of 20 m, whereas H. subpilosus dominated the chironomid assemblage at 30–40 m. At 20-m depth, the chironomid density was highest in June, decreased towards autumn, and was relatively stable during the ice-covered period. The peak density in June was mainly related to a strong seasonal pattern in the density of Heterotrissocladius maeaeri and M. thienemanni. At 30–40-m depth, no significant seasonal variations in total density of chironomid larvae were observed, although the density of H. subpilosus exhibited a significant seasonal peak in winter. Larval instar groups of H. subpilosus were identified from a classification based on head capsule width. The profundal dwelling H. subpilosus were hemivoltine, having predominantly a two-year life cycle.

Nõlvak, H., Sildvee, T., Kriipsalu, M. & Truu, J. 2012: Application of microbial community profiling and functional gene detection for assessment of natural attenuation of petroleum hydrocarbons in boreal subsurface. Boreal Env. Res. 17: 113–127.

Microbial community structure and functional gene diversity were assessed in subsurface soil and groundwater samples collected from a previously remediated site with residual oil contamination. Primers for functional gene detection and enumeration were designed and tested in order to better quantify pollutant degradation potential in the subsurface soil and groundwater. Results indicate that the study area contains variety of bacteria with capacity to degrade monoaromatic solvents (BTEX), alkanes, low molecular weight PAHs and phenols. Functional genes related to BTEX, phenol and alkane degradation were widely distributed and were found to be especially abundant in zones with higher residual contamination. Results suggest that the indigenous subsurface microbial community at the study site has versatile catabolic potential to degrade different oil compounds. This characteristic is an important prerequisite for the application of natural contaminant attenuation and the successful monitoring of this approach for site remediation.

Ruoho-Airola, T. 2012: Comparison of atmospheric concentrations of sulphur and nitrogen compounds, chloride and base cations at Ähtäri and Hyytiälä, Finland. Boreal Env. Res. 17: 128–138.

Seven-year (2003–2009) time series of atmospheric SO₂, SO₄^2–, NO₃^–, NH₄⁺ and Cl^– concentrations as well as four-year time series of atmospheric Na⁺, K⁺, Ca²⁺ and Mg²⁺ concentrations from Ähtäri and Hyytiälä background stations in southern Finland, located within 85 km of each other were compared. At Ähtäri the air sampler was located in a clearing within a young forest, while at Hyytiälä it was within dense forest stands. Pearson's correlations between the time series were very strong (r_P ≥ 0.9) for SO₂, SO₄^2–, NO₃^–, NH₄⁺, Cl^– and Ca²⁺, strong (r_P > 0.8) for Na⁺ and Mg²⁺ and week (r_P = 0.65) for K⁺. The concentrations recorded at Hyytiälä were on average 0.8–1.0 times those at Ähtäri, although for K⁺ and Ca²⁺ the ratios were higher. The GLS-ARMA method used takes into account the seasonal behaviour and serial correlation in the air quality time series, which revealed similar seasonal and temporal behaviour for S and N compounds and Cl^– at both stations. As a result of the dense seasonalization of the time series, the part of the data heavily influenced by local agricultural sources could be identified. This enables elimination of the minimal part of the data affected and the use of the remaining data for further studies on a more regional level.

Huusko, A. & Hyvärinen, P. 2012: Atlantic salmon abundance and size track climate regimes in the Baltic Sea. Boreal Env. Res. 17: 139–149.

Atmospheric variations on multi-decadal time scales, or climate regimes, can cause significant alterations throughout the physical environment, often with remarkable consequences for animal populations and ecosystems. Here we report that the climate regimes in the Baltic Sea area, which are based on the North Atlantic Oscillation and two more regional oceanographic variables, account for the observed dynamics of Atlantic salmon abundance and size in the sea. The changes in the salmon abundance and size followed changes in the climate regimes in the Baltic Sea area, indicating that high amplitude shifts in the Atlantic salmon performance are closely associated with longer-term patterns in the climate. During maritime, temperate regimes salmon were larger in size but low in abundance, with contrasting characteristics during continental, cold climate regimes. Therefore, Atlantic salmon seem to provide a very sensitive indicator of the biological effects of climate-forced changes in the aquatic environment.

Kriauciuniene, J., Meilutyte-Barauskiene, D., Reihan, A., Koltsova, T., Lizuma, L. & Sarauskiene, D. 2012: Variability in temperature, precipitation and river discharge in the Baltic States. Boreal Env. Res. 17: 150–162.

The climate change impact on water resources is observed in all the Baltic States. These processes became more evident in the last decades. Although the territory of the Baltic States (Lithuania, Latvia, Estonia) is not large (175 000 km²), the climatic differences are quite considerable. We performed a regionalization of the territory of the Baltic States depending on the conditions of river runoff formation which can be defined according to percentages of the river feeding sources (precipitation, snowmelt, groundwater). Long-term series of temperature (40 stations), precipitation (59 stations) and river discharge (77 stations) were used to compose ten regional series. This paper addresses: (1) variability in long-term regional series of temperature, precipitation and river discharge over a long period (1922–2007); (2) changes in regional series, comparing the periods 1991–2007 and 1931–1960 with the reference period (1961–1990), and (3) the impact of temperature and precipitation changes on regional river discharge.