Ilus, E., Vartti, V.-P., Ikäheimonen, T.K., Mattila, J. & Klemola, S. 2002. Technetium-99 in biota samples collected along the Finnish coast in 1999. Boreal Env. Res. 7: 91–97.

The aim of the study was to develop a method for analysing ⁹⁹Tc at STUK, and to establish whether ⁹⁹Tc can be detected in Finnish coastal waters. Samples of Fucus vesiculosus, Myriophyllum spp., Macoma baltica, Mytilus edulis, Saduria entomon and seawater were collected at more than 30 stations along the western and southern coasts of Finland for ⁹⁹Tc analysis. Small amounts of ⁹⁹Tc were observed in all the Fucus samples collected; the activity concentrations ranged from 1.6 to 11.6 Bq kg^–1 dry wt. The highest concentrations were found in two samples taken from the northernmost stations in the Quark, probably for biological reasons. Due to the low salinity of the water, Fucus vesiculosus is very slow-growing and small in this area, which is at the extreme limit of its permanent distribution range in the Baltic Sea. In seawater and in all the other biota samples, the concentration of ⁹⁹Tc was below the detection limit, which supports the use of Fucus as an indicator organism for ⁹⁹Tc in the marine environment. Global fallout from atmospheric nuclear weapons tests carried out in the 1950s and 1960s is certainly the most important source of ⁹⁹Tc detected in Fucus on the Finnish coast. In addition, the samples were analysed for gamma-emitting radionuclides.

Ikäheimoinen, T.K. & Saxén, R. 2002. Transuranic elements in fishes compared to ¹³⁷Cs in certain lakes in Finland. Boreal Env. Res. 7: 99–104.

Transuranic elements from Chernobyl fallout were detected in freshwater fish sampled in Finland after the accident. Maximum concentrations of ^239,240Pu, ²⁴¹Pu, ²⁴¹Am and ²⁴²Cm were 3.3, 110, 2.6 and 340 mBq kg^–1, respectively. In certain samples, ²³⁸Pu/^239,240Pu ratios were between 1.0 and 7.2 while the expected value was 0.5. This could indicate differences in environmental mobilization between ²³⁸Pu and ^239,240Pu. The concentration factor (CF) for Am from water to fish flesh, 230, was more than 2 times higher than the figure of 84 for Pu. The CF for Cm, 5100, was considerably higher than that of Am and does not confirm the presence of similar biological behaviour for Am and Cm. The average transfer factor (TF) from deposition to fish was highest for ¹³⁷Cs, 44 x 10^–3 m² kg^–1. This was somewhat higher than the TF for Am but more than 10 times higher than that for Pu. Transuranic depositions that could cause the European Council regulation limit in freshwater fish to be exceeded are, Pu and Am respectively, 3000 and 1500 times higher than the highest fallout of Pu and Am recorded in Finland following the Chernobyl accident.

Saxén, R. & Koskelainen, U. 2002. Distribution of ¹³⁷Cs and ⁹⁰Sr in various tissues and organs of freshwater fish in Finnish lakes. Boreal Env. Res. 7: 105–112.

The degree of radiocontamination in fish is usually analysed to estimate doses to fish consumers, for which the radionuclide contents in the edible parts of fish are needed. Recently increasing attention has been focused on radiation protection in plants and animals. To estimate the effects of radiation on fish, the distribution of radionuclides in various organs and radiosensitivity of the organs must be known. A step towards this was taken when the Radiation and Nuclear Safety Authority (STUK) of Finland determined the distribution of ¹³⁷Cs and ⁹⁰Sr in muscle tissue, skin + fins, and bones in perch samples, in muscle and bones or in muscle, skin + fins, and bones in pike samples and in muscle + skin + fins and bones in vendace samples. Accumulation of ¹³⁷Cs in fish liver, spawn and sperm was also studied and compared with respective values in the edible parts. The importance of skin and fins was evident as a source of ⁹⁰Sr to fish. Fish sperm showed somewhat higher activity concentrations of ¹³⁷Cs than muscle.

Isaksson, M. 2002. Sampling methods for pasture, soil and deposition for radioactivity emergency preparedness in the Nordic countries. Boreal Env. Res. 7: 113–120.

The aim of this work was to compare sampling techniques for pasture, soil and deposition, planned for radioactivity surveillance in emergency situations in the Nordic countries. The basis of the survey was a questionnaire, sent to radiation protection authorities and laboratories. Sampling of pasture is performed with a cutting height between 1 and 5 cm above the ground from an area of about 1 m². The sampling plots are usually randomly positioned. Soil samples, 3 to 20 cores in various patterns, are generally taken by a corer of varying diameter. For deposition sampling, precipitation collectors of different sizes are used. When comparing results, the differences between laboratories should be borne in mind so that proper corrections can be made. It is, however, important to consider that, especially in an emergency situation, the use of standardised methods may worsen the results if these methods are not part of the daily work.

Lehtiniemi, M., Viitasalo, M. & Kuosa, H. 2002. Diet composition influences the growth of the pelagic mysid shrimp, Mysis mixta (Mysidacea). Boreal Env. Res. 7: 121–128.

We studied the growth, feeding, and elemental composition of Mysis mixta from June to September 1997 in the northern Baltic Sea. In June the juvenile population had a unimodal size distribution (mean length ~6 mm), but in July–August, the population was divided into two cohorts. A stomach content analysis showed that the mysids in the larger and faster growing cohort fed significantly more on crustacean zooplankton and pelagic material than the smaller one: the mean ratios of zooplankton:phytoplankton and pelagic:benthic particles in July–August were respectively 0.27 and 0.11 for the small cohort, and 0.54 and 0.36 for the large cohort. This suggests that food quality and its energy content are important in influencing the growth of pelagic mysids in the northern Baltic. The C:N ratio of the two cohorts did not vary much, which shows that ingestion of food items with varying elemental content is not necessarily reflected in the elemental composition of consumers.

Pakkanen, T.A. & Hillamo, R.E. 2002. Comparison of sampling artifacts and ion balances for a Berner low-pressure impactor and a virtual impactor. Boreal Env. Res. 7: 129–140.

Between April 1996 and June 1997, parallel fine particle aerosol samples were collected with a virtual impactor (VI) and a Berner low-pressure impactor (BLPI) at both an urban and a rural site in the Helsinki area. The average size distributions for particulate sulphate, ammonium, oxalate, succinate, MSA, Na⁺, K⁺ and Mg²⁺ were similar at the two sites, while average concentrations were slightly higher at the urban site. Average BLPI/VI ratios of Na⁺, K⁺ and succinate were close to one indicating that no major sampling artifacts for these ions were present. The corresponding ratios were larger than one for Ca²⁺ and Mg²⁺, suggesting that some particle bounce-off occurred in the BLPIs. The ratios smaller than one for pyruvate, malonate, oxalate, ammonium, glutarate, MSA, and sulphate suggest that some fraction of these ions was formed from gaseous precursors on the VI Teflon filters. Particulate nitrate evaporated from the VI Teflon filters and from the BLPI, the average evaporation percentages varying between about 50%–65%. Chloride seemed to evaporate from the VI Teflon filters, the evaporation being more pronounced at the urban site where the concentration of gaseous SO₂ was higher. The fine particle cation/anion ratios were lower for the VI at both sites, and higher at the rural site for both sampler types. The contribution of organic anions to total anions was higher during the summer than during the winter for fine particles, even though these contributions were similar for ultrafine particles.

Hussein, T., Hämeri, K. & Kulmala, M. 2002. Long-term indoor-outdoor aerosol measurement in Helsinki, Finland. Boreal Env. Res. 7: 141–150.

Total aerosol number concentration measurements were carried out with a condensation particle counter in a Helsinki suburban area throughout the period from 1 November 1999 to 30 June 2000. The variation of the aerosol concentration was investigated in connection with the season, meteorological conditions and traffic activity, which were concluded as the main factors affecting the outdoor aerosol concentrations. In addition, the indoor-outdoor connection was investigated based on the indoor/outdoor (I/O) concentration ratio. Two daily patterns of the total aerosol number concentration were observed in each season, one for weekdays and another for weekends. On average, the submicron aerosol number concentration was at its highest during the winter and lowest during the summer. The temporal variation of the total aerosol number concentration indoors followed the outdoor variation with a small delay. Larger I/O ratios (average 0.66) were observed during the summer than during the winter and the spring (average 0.58).

Liikanen, A., Tanskanen, H., Murtoniemi, T. & Martikainen, P. J. 2002. A laboratory microcosm for simultaneous gas and nutrient flux measurements in sediments. Boreal Env. Res. 7: 151–160.

We developed a laboratory microcosm to study simultaneously the dynamics of gases and nutrients in sediments. With the microcosm, intact sediment cores were incubated under continuous water flow. The incubation system was constructed so that diffusion and ebullition of gases could be measured separately. Here we show results from an experiment conducted with littoral, shallow and deep profundal sediments of Lake Kevätön using oxic and anoxic water flow. The fluxes of important greenhouse gases (methane, carbon dioxide, and nitrous oxide) and nutrients (phosphorus, ammonium, nitrite and nitrate) were determined. Deep profundal sediments released carbon gases, methane and carbon dioxide, and nutrients, ammonium and phosphorus, especially in anoxic conditions. Also the littoral sediment was important source of methane. Nitrous oxide, nitrite and nitrate were produced in the shallow profundal sediments with the oxic flow. Our microcosm was a promising tool to differentiate gas and nutrient dynamics between sediments under controlled conditions.

Artimo, A. 2002. Application of flow and transport models to the polluted Honkala aquifer, Säkylä, Finland. Boreal Env. Res. 7: 161–172.

High concentrations of tetrachloroethylene were discovered in groundwater samples taken from the Honkala aquifer in the municipality of Säkylä in southwestern Finland. The contamination was traced to a dry-cleaning laundry located close to a tributary esker which is connected to the Säkylänharju esker in the northeastern part of the area. The Weichselian and Holocene sediments of the area include till, sand and gravel and also glacial and postglacial clay deposits. The groundwater flows west towards Pyhäjärvi (a lake in the municipality of Säkylä). A study was launched to test the applicability of numerical groundwater models in developing an overview of groundwater flow and contaminant transport in the area and prediction of the timing of natural attenuation. Modelling was conducted with the MODFLOW, MODFLOWP and MT3D codes, the resulting simulations indicating a natural attenuation time of more than 30 years would be required for the aquifer. Active aquifer restoration would require pumping and treatment of the polluted groundwater.