BER 21(5-6), 2016

ISSN 1239-6095 (print), ISSN 1797-2469 (online)
© Boreal Environment Research 2016

Contents of Volume 21 no. 5–6

Vahteri P. & Vuorinen I. 2016: Continued decline of the bladderwrack, Fucus vesiculosus, in the Archipelago Sea, northern Baltic proper. Boreal Env. Res. 21: 373–386.
Abstract
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Svensson N., Bergström H., Sahlée E. & Rutgersson A. 2016: Stable atmospheric conditions over the Baltic Sea: model evaluation and climatology. Boreal Env. Res. 21: 387–404.
Abstract
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Mustamo P., Maljanen M., Hyvärinen M., Ronkanen A.-K. & Kløve B. 2016: Respiration and emissions of methane and nitrous oxide from a boreal peatland complex comprising different land-use types. Boreal Env. Res. 21: 405–426.
Abstract
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Lakkala K., Jaros A., Aurela M., Tuovinen J.-P., Kivi R., Suokanerva H., Karhu J.M. & Laurila T. 2016: Radiation measurements at the Pallas-Sodankylä Global Atmosphere Watch station — diurnal and seasonal cycles of ultraviolet, global and photosynthetically-active radiation. Boreal Env. Res. 21: 427–444.
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Aarnio M.A., Kukkonen J., Kangas L., Kauhaniemi M., Kousa A., Hendriks C., Yli-Tuomi T., Lanki T., Hoek G., Brunekreef B., Elolähde T. & Karppinen A. 2016: Modelling of particulate matter concentrations and source contributions in the Helsinki Metropolitan Area in 2008 and 2010. Boreal Env. Res. 21: 445–460.
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Lennox R.J., Mayer I., Havn T.B., Johansen M.R., Whoriskey K., Cooke S.J., Thorstad E.B. & Uglem I. 2016: Effects of recreational angling and air exposure on the physiological status and reflex impairment of European grayling (Thymallus thymallus). Boreal Env. Res. 21: 461–470.
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Tuovinen H., Pohjolainen E., Vesterbacka D., Kaksonen K., Virkanen J., Solatie D., Lehto J. & Read D. 2016: Release of radionuclides from waste rock and tailings at a former pilot uranium mine in eastern Finland. Boreal Env. Res. 21: 471–480.
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Svensson J., Virkkula A., Meinander O., Kivekäs N., Hannula H.-R., Järvinen O., Peltoniemi J.I., Gritsevich M., Heikkilä A., Kontu A., Neitola K., Brus D., Dagsson-Waldhauserova P., Anttila K., Vehkamäki M., Hienola A., de Leeuw G. & Lihavainen H. 2016: Soot-doped natural snow and its albedo — results from field experiments. Boreal Env. Res. 21: 481–503.
Abstract
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Lindroos A.-J., Derome K., Piispanen J. & Ilvesniemi H. 2016: Geochemical changes in podzolic forest soil 17 years after deep tilling. Boreal Env. Res. 21: 504–512.
Abstract
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Mikomägi A., Koff T., Martma T. & Marzecová A. 2016: Biological and geochemical records of human-induced eutrophication in a small hard-water lake. Boreal Env. Res. 21: 513–527.
Abstract
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Brulińska D., Olenycz M., Ziółkowska M., Mudrak-Cegiołka S. & Wołowicz M. 2016: Moon jellyfish, Aurelia aurita, in the Gulf of Gdansk: threatening predator or not? Boreal Env. Res. 21: 528–540.
Abstract
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Marttila H., Nieminen M.L., Ärje J., Meissner K., Tuukkanen T., Saukkoriipi J. & Kløve B. 2016: Dynamics and temporal changes in suspended sediment transport in northern Finland: transport of very fine particulate matter. Boreal Env. Res. 21: 541–555.
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Eskelinen R., Ronkanen A.-K., Marttila H., Isokangas E. & Kløve B. 2016: Effects of soil frost on snowmelt runoff generation and surface water quality in drained peatlands. Boreal Env. Res. 21: 556–570.
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Niemistö J., Köngäs P., Härkönen L. & Horppila J. 2016: Hypolimnetic aeration intensifies phosphorus recycling and increases organic material sedimentation in a stratifying lake: Effects through increased temperature and turbulence. Boreal Env. Res. 21: 571–587.
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Errata. Boreal Env. Res. 21: 588.
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Vahteri P. & Vuorinen I. 2016: Continued decline of the bladderwrack, Fucus vesiculosus, in the Archipelago Sea, northern Baltic proper. Boreal Env. Res. 21: 373–386.

Before the 1980s, the bladderwrack (Fucus vesiculosus) formed extensive belts along the SW coast of Finland, but already then it began to decline especially in sheltered bays of the inner archipelago. We studied underwater vegetation by scuba diving in 1993–2007. By 2007, six out of eleven sites had lost their Fucus belts, and sheltered bays had become refuges for the bladderwrack. In 2006–2007, we studied the effects of temperature, transparency, bottom type, shoreline orientation and location on the bladderwrack distributions and depth penetrations at 61 locations across different archipelago zones. Of these, only location indicated a possible effect.

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Svensson N., Bergström H., Sahlée E. & Rutgersson A. 2016: Stable atmospheric conditions over the Baltic Sea: model evaluation and climatology. Boreal Env. Res. 21: 387–404.

The WRF (Weather Research and Forecasting model) was evaluated against flight measurements over the Baltic Sea during stable conditions, focusing on vertical profiles of temperature and wind speed. Six different boundary layer parameterization schemes were used. It is shown that there are generally small differences between the boundary layer schemes, and that all schemes have problems in capturing the strength and height of low-level jets. Climatological simulations over the Baltic Sea show that there is a strong seasonality in the stability over the sea with up to 80% stable conditions in spring as compared with 10% in winter. Low-level jets are common, and occur up to 45% of the time in spring. The entire Baltic Sea, not only its coastal areas, is affected by stable stratification.

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Greenhouse gas (GHG) emissions from pristine peatlands and peatlands drained for agriculture, forestry or peat extraction have been studied intensively. However, few studies have compared GHG emissions from peatlands under different land-use type within the same peatland area. This study examined methane (CH₄) and nitrous oxide (N₂O) emissions and respiration (CO₂) from a peatland complex in northern Finland, including a peatland used for grass cultivation, a Pinus sylvestris and Betula pubescens dominated forested peatland, a peat-extraction site and a pristine mire. Gas fluxes were measured in 2011 and 2012 with chambers during the snow-free period, and using the snow-gradient method in winter 2012/2013. Soil respiration was highest in the cultivated site (median during growing season 350 mg CO₂ m^–2 h^–1), and lower in the forest site and in the peat-extraction site (median for growing season 49 and 130 mg CO₂ m^–2 h^–1, respectively). The peat-extraction site and the cultivated site were large sources of N₂O during the growing season (median 89 and 28 µg m^–2 h^–1, respectively) and during the winter (median 56 and 460 µg m^–2 h^–1, respectively). The pristine site was a large source of CH₄ during the growing season (median 0.98 mg m^–2 h^–1), whereas CH₄ emissions from the drained sites during the growing season were minor. However, during winter, the peat-extraction site and the cultivated site emitted CH₄ (median 0.58 and 0.029 mg m^–2 h^–1, respectively). The cultivated site had the highest estimated CO₂ equivalent emissions, due to the high CO₂ and N₂O fluxes, but the peat-extraction site also had large annual emissions, mainly as N₂O. The study suggests that rising groundwater level from 60 to 40 cm could potentially mitigate the emissions from the cultivated site.

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We present time series of solar ultraviolet radiation (UVR), global radiation, and photosynthetically-active radiation (PAR) measurements from the Pallas-Sodankylä Global Atmosphere Watch (GAW) station at Sodankylä for the period 1990–2013. Measurements were performed both in an open area and in the surrounding boreal forest, which had a total leaf area index of 3.6. We present a method to homogenize multifilter radiometer UV time series. Using this method, the relative mean differences between the multifilter radiometer and the reference spectroradiometer were 5% for UVB and erythemally-weighted dose rates, for all sky conditions and solar zenith angles (SZA) smaller than 60° during the period 2008–2012. Our results show that daily doses measured in the forest were four times smaller than those measured in the nearby open area. Maximum UVB (280–320 nm) and UVA (320–400 nm) daily doses of 75.0 kJ m^–2 and 1.74 MJ m^–2, respectively, were measured during the period of multifilter radiometer measurements, 2002–2012. The maximum daily sum of global radiation during the years 2000–2010 was 31.4 MJ m^–2, measured in 2010. The maximum PAR during 2000–2012 was 1830 µmol m^–2 s^–1, measured in 2000. For the entire period of spectral UV measurements, 1990–2013, a maximum UV index of 6 was measured in 2011 and 2013.

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We refined an urban-scale dispersion modelling system by adding a road dust suspension model, FORE. The deterministic modelling includes both vehicular exhaust emissions (including cold start and cold driving) and suspended road dust. The urban scale modelling system was used in combination with the regional scale chemical transport model LOTOS-EUROS, for 2008, and the measured regional background concentrations, for 2010. The predictions were compared against measured concentrations of PM_2.5 and PM₁₀. PM_2.5 concentrations were slightly and the PM₁₀ concentrations substantially under-predicted in 2008, mainly due to the under-predicted regional background concentration. Source contributions of suspended road dust varied from 2% to 8% and from 12% to 38% for PM_2.5 and PM₁₀, respectively. Long-range transported contributions at the urban traffic stations were 72% to 92% for PM_2.5 and 50% to 83% for PM₁₀.

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European grayling (Thymallus thymallus) is a popular recreational fish that may be lifted out of the water to facilitate hook removal or for admiration. To evaluate the effects of air exposure and angling-induced exhaustive exercise on released grayling condition, we assessed blood physiology and reflexes of grayling after angling and air exposure in the subarctic River Lakselva (Norway) at midsummer temperatures (i.e., 17–18 °C). Blood samples were drawn 30 min after angling and analyzed for lactate anions, glucose, sodium ions, and pH. Reflex impairment was determined with orientation and tail grab reflex action assessments immediately after landing, after air exposure, and after 30 min holding. Blood physiology did not indicate an exacerbating effect of air exposure relative to just angling-induced exercise, but significant and prolonged reflex impairment was associated with the 120 s air exposure interval. Anglers must take care to minimize air exposure to adhere to best handling practices.

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The Paukkajanvaara mine in Eno, eastern Finland, started to operate in 1959. The mine was a test site for assessing the feasibility of larger-scale uranium extraction. Pilot-scale mining and milling were carried out between 1958 and 1961, and the mine site was rehabilitated in the early 1990s. The aim of this study was to examine the potential for further mobilization of radionuclides after remediation. There are two primary sources of contamination at the site, the waste-rock pile and the tailings. Our study indicates that ²²⁶Ra leached from the waste-rock pile and accumulated in surrounding soil. In run-off sediment samples collected from a dry stream bed near the waste-rock pile, the activity concentrations of ²²⁶Ra and ²³⁸U were higher than in soil samples. From the tailings, radionuclides can leach directly to the lake and to another small stream, which flows to the east of the waste-rock pile. In the water samples collected from this stream, uranium concentrations increased at the outlet to the lake. The results from the soil samples collected between the tailings area and the stream indicate leaching of ²³⁸U and ²²⁶Ra with the surface flow. Sediment samples collected from the bottom of the lake displayed pronounced uranium series disequilibrium with fractionations of ²¹⁰Pb and ²²⁶Ra relative to the parent ²³⁸U. The results therefore indicate that leaching and accumulation of at least ²²⁶Ra from the waste-rock pile and possibly tailings is still ongoing.

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Soot has a pronounced effect on the cryosphere and experiments are still needed to reduce the associated uncertainties. This work presents a series of experiments to address this issue, with soot being deposited onto a natural snow surface after which the albedo changes were monitored. The albedo reduction was the most pronounced for the snow with higher soot content, and it was observed immediately following soot deposition. Compared with a previous laboratory study the effects of soot on the snow were not as prominent in outdoor conditions. During snowmelt, about 50% of the originally deposited soot particles were observed to remain at the snow surface. More detailed experiments are however needed to better explain soot’s effect on snow and to better quantify this effect. Our albedo versus soot parameterization agreed relatively well with previously published relationships.

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Lindroos A.-J., Derome K., Piispanen J. & Ilvesniemi H. 2016: Geochemical changes in podzolic forest soil 17 years after deep tilling. Boreal Env. Res. 21: 504–512.

Mechanical site preparation, e.g. ploughing, is commonly used in connection with regeneration of forests after clear-cut. Ploughing causes disturbances in the properties of the original soil profile. The aim of this study was to determine changes in concentrations of elements in the podzolic soil horizons exposed to soil-forming processes such as weathering due to deep tilling in boreal forest soil located in southern Finland. The total concentrations of elements were determined by X-ray fluorescence (XRF) for the podzolic soil horizons collected from undisturbed soil, tilt, undisturbed soil below the tilt and furrow 17 years after clear-cut and deep tilling. Depletion of the elements by chemical weathering occurred in the topmost horizons of the furrow within 17 years after exposure of the B horizon to soil-forming processes caused by deep tilling. In the tilt horizons, the dominant factor affecting changes in concentrations was mixing of the original horizons as a result of deep tilling, which masked possible depletion due to weathering.

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Mikomägi A., Koff T., Martma T. & Marzecová A. 2016: Biological and geochemical records of human-induced eutrophication in a small hard-water lake. Boreal Env. Res. 21: 513–527.

In areas with a long history of urbanization and agriculture, ecological properties of lakes can be substantially altered by anthropogenic eutrophication. We used a paleolimnological approach to identify how anthropogenic change affected a hard-water lake ecosystem during the last 200 years. Using sedimentary pigments, green algal remains, pollen analyses and stable carbon and oxygen isotopes (δ¹³C_carb and δ¹⁸O_carb), we assessed the dynamics of paleo-indicators of eutrophication in Lake Verevi (southern Estonia) and compared these with historical evidence and limnological surveys. The study site was also selected to quantify the impact of a documented change in water level on sedimentary pigment preservation (via changes in oxygen and light availability) and green algal remains (whose abundance is higher in the littoral zone). In addition, the ratio of chlorophyll a to pheophytin a provided valuable information on sedimentation conditions, and thus, helped interpret the variation in sedimentary pigments concentrations. All indicators showed a synchronous ecological response to an increasingly pronounced anthropogenic impact. Furthermore, our results showed that the first sign of eutrophication was present as early as the 19th century, as indicated by a sharp rise in green algae (Pediastrum), more positive δ¹³C_carb values, and a pronounced increase in phytoplankton pigment concentrations. Pollen data showed that these changes coincided with land clearance and the start of agricultural activities. The δ¹³C_carb and δ¹⁸O_carb data were strongly correlated and enriched isotopic content coincided with the eutrophication signal.

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The seasonal population dynamics and feeding preferences of the moon jellyfish, Aurelia aurita, in the Gulf of Gdansk (southern Baltic Sea) were investigated. Medusae were present in the water column from June to November, with maximum occurrence in August and September. The medusa bell diameter and weight increased during the study period reached maximum values in October. The relationship between bell diameter and wet weight was strong. No ephyrae were observed during the study period. Gastric content analysis revealed that the medusae fed mainly on copepods and cladocerans. Rotifers that dominated the water column throughout the study period were not found in the jellyfish guts, but the stable isotope signature indicated that they could have been a significant source of derived carbon. Low numbers of plankton prey and the lack of fish larvae in A. aurita guts suggest that the jellyfish is of minor relevance as a predator and competitor in the Gulf of Gdansk.

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Quantification of suspended sediment yield from rivers is essential to determining how land cover and land use affect water quality in fluvial ecosystems and erosion rates in catchment basins. In this study we used long-term (1967–2011) river-runoff and sediment-concentration data to seek new insights into suspended sediment transport and its governing factors. We found that long-term suspended sediment concentrations and yield of very fine sediment (< 0.4–1.2 µm) are dependent on: (i) temporal changes in biogeochemical processes in catchment soils and fluvial systems, and (ii) temporal variations in metal humate colloid concentrations, especially in peat-covered catchments. The results also showed that the proportion of very fine sediment varies seasonally and can significantly affect transport rates in boreal rivers. Thus national monitoring activities should include parameters describing the quality of suspended sediment (e.g. particle size range and loss-on-ignition) in order to provide information relevant to land management and ecological assessments in boreal rivers.

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Runoff generation and fluxes of dissolved elements were studied in two drained peatlands under different land uses during spring snowmelt 2012. One site experienced soil frost, whereas the other site was frost-free due to groundwater seepage. Runoff water was sampled at 12-hour intervals during the snowmelt peak and soil and snow samples were taken. All samples were analysed for oxygen-18 isotope and various water quality parameters. The results demonstrated the effect of soil frost on water flow paths, which further affected runoff water quality. At the frost-free site, seepage through the peat soil profile was the main flow route during snowmelt runoff generation, which could be seen e.g., as high DOC concentration in the stream. At the site with soil frost, meltwater could not infiltrate into the soil, leading to overland flow and lower concentrations of elements in water during the peak snowmelt period.

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The effect of hypolimnetic aeration on the sedimentation of inorganic and organic material as well as phosphorus was examined in a spatially comprehensive investigation in a dimictic northern temperate lake in southern Finland. Two years of aeration strongly increased the gross sedimentation of dry matter (68% ± 2%, mean ± SD) and phosphorus (87% ± 7%) in the aerated, deep areas. Although the organic content of the settling material decreased, the total amount of organic matter reaching the lake bottom increased by 53% ± 6%. Also the shallow areas were affected, although to a lesser extent. We suggest that the observed increases were due to an aeration-induced increase in the hypolimnetic water temperature and turbulence, which not only increased the mineralization of organic matter but also phosphorus recycling, and consequently the production of excess organic material.