Airborne 210Pb, Si, Zn and Pb as tracers for atmospheric pollution in Helsinki metropolitan area

This study analyzed 16070 daily and 608 weekly air filter samples from the Helsinki metropolitan area collected between 1962 and 2005. The aim was to use the Potential Source Contribution Function (PSCF) to determine potential sources of silicon (Si), zinc (Zn), lead (Pb), and radioactive isotope 210Pb. The main sources for Si and Pb were industrial activities, particularly mining, metal industry, and traffic. Common source areas for Zn and 210Pb were identified in the eastern and southeastern parts of the measuring site.

137Cs and isotopic ratios of Pu and U in lichens and mosses from Russian Arctic areas

Knowledge of past anthropogenic sources of radionuclide contamination in Russian Arctic areas is important to assess the radioecological situation of these less-studied regions. Therefore, we investigated the sources of radionuclide contamination in Russian Arctic in the 1990s. Lichen and moss samples were collected from 1993 to 1996 in Kola Peninsula, Franz Josef Land, and few other locations. The activity concentration of 137Cs was determined from the archived samples by gamma spectrometry in 2020. After radiochemical separation of Pu and U isotopes from the lichens and mosses, mass ratios 240Pu/239Pu, 234U/238U, 235U/238U, and 236U/238U were determined by mass spectrometry. 137Cs activity concentrations at the sampling date were found to vary from 3.1 ± 1.4 (Inari, Finnish-Russian border) to 303 ± 7 (Kola Peninsula) Bq/kg. The ranges of isotopic ratios were 0.0592 ± 0.0007 to 0.253 ± 0.082 for 240Pu/239Pu, (4.89 ± 3.91) × 10-5 to (6.86 ± 0.04) × 10-5 for 234U/238U, 0.0072104(21) to 0.007376(41) for 235U/238U, and from below 1 × 10-7 to (2.65 ± 0.19) × 10-6 for 236U/238U, respectively. Based on the measured isotopic ratios and characteristic isotopic ratios of known contamination sources, the main Pu and U sources in the sampled lichens and mosses are global fallout, the Chernobyl accident, and possibly local nuclear activities. These results contribute to further understanding of past nuclear events and resulting nuclear contamination in Russian Arctic terrestrial areas.

Evaluation of 137Cs, 133Xe and 3H activity concentrations monitored in the Arctic atmosphere

This paper provides a brief introduction to the Arctic atmospheric radioactivity monitoring network. A decade of monitoring results have shown the ¹³⁷Cs background levels in Arctic air range from 0.05 to 1.50 μBq/m³. The monitoring stations have sufficient sensitivity to detect ¹³⁷Cs brought to the atmosphere due to resuspension in local soil and reemissions from biomass burning in a daily temporal resolution. These observations can be used as tracers for atmospheric processes. The ¹³³Xe measurements obtained at Yellowknife, Resolute and Spitsbergen could support other research into how air pollution problems arise across intercontinental distances. It will help develop and improve models capable of predicting the long-distance transport and deposition of trace gases in the Arctic. Rainwater monitoring data collected in Finnish Lapland since the 1960's indicate that ³H radioactivity concentrations reached natural background levels in early 2000s, typically around 1-2 Bq/L monthly, with an annual seasonal variation cycle consistent with the observed of other cosmogenic radionuclides.

Air radioactivity in Marambio Base: The peculiar character of Antarctic Peninsula

The Antarctic region is considered to be the least contaminated in the world due to its specific location and separation of this area as well as low activity of humans (Hashimoto et al., 1988). Additionally, in accordance with the provision of the Antarctic Treaty System (Antarctic Treaty Secretariat, 2020) it is prohibited to conduct any actions with nuclear materials in this area. Nevertheless, Antarctica is not free from radioactive pollutants (human activity, nuclear tests or accidents) created in other parts of the world and transported by air masses or sea currents to the region of the South Pole where they can be detected. This paper presents results of measurements of activity concentrations of both natural and artificial gamma-ray emitting isotopes present on air-filters exposed in the ground level of the air in Marambio Base (Antarctic Peninsula). Furthermore, comparison with results obtained from other part of Antarctica were performed (i.e. Aboa Station, including radioisotope sources estimation). Investigation suggests that the northern part of the Antarctic Peninsula is effectively isolated from the Antarctic mainland and, in case of air radioactivity, should be considered separately.

Separation method for Pu, Am and Sr in large air filter sample sets

A sequential separation method for Pu, Am, and Sr was applied for unusually large sample sets of air filters. The sample sets were combined weekly air filters covering sampling time from three months to five years, while in original method, the analyzed air filters had sampling time of only 1-3 days, containing significantly less organic and inorganic matrix and natural radionuclides. The separation method is based on ashing and wet-ashing, followed by column separations with extraction chromatography and anion exchange. Reference materials IAEA-447, IAEA-384, and NIST-SRM-4353A were analyzed with the modified separation method. IAEA-384 was representing best the composition and radionuclide level in the air filter samples.•

Compared to the original method, sample ashing took considerably longer time (one day vs. several days).

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High concentration of natural radionuclides in the large air filter sample sets interfered first the determination of ²⁴¹Am and ⁹⁰Sr, until an anion exchange step was adopted for removal of ²¹⁰Bi and ²¹⁰Po from Am and Sr fractions.

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After modification, the method is suitable for separating artificial radionuclides ^238,239,240Pu, ²⁴¹Am, and ⁹⁰Sr from large sample sets of air filters.

Decreased carbon accumulation feedback driven by climate-induced drying of two southern boreal bogs over recent centuries

Northern boreal peatlands are important ecosystems in modulating global biogeochemical cycles, yet their biological communities and related carbon dynamics are highly sensitive to changes in climate. Despite this, the strength and recent direction of these feedbacks are still unclear. The response of boreal peatlands to climate warming has received relatively little attention compared with other northern peatland types, despite forming a large northern hemisphere-wide ecosystem. Here, we studied the response of two ombrotrophic boreal peatlands to climate variability over the last c. 200 years for which local meteorological data are available. We used remains from plants and testate amoebae to study historical changes in peatland biological communities. These data were supplemented by peat property (bulk density, carbon and nitrogen content), 14 C, 210 Pb and 137 Cs analyses and were used to infer changes in peatland hydrology and carbon dynamics. In total, six peat cores, three per study site, were studied that represent different microhabitats: low hummock (LH), high lawn and low lawn. The data show a consistent drying trend over recent centuries, represented mainly as a change from wet habitat Sphagnum spp. to dry habitat S. fuscum. Summer temperature and precipitation appeared to be important drivers shaping peatland community and surface moisture conditions. Data from the driest microhabitat studied, LH, revealed a clear and strong negative linear correlation (R2  = .5031; p < .001) between carbon accumulation rate and peat surface moisture conditions: under dry conditions, less carbon was accumulated. This suggests that at the dry end of the moisture gradient, availability of water regulates carbon accumulation. It can be further linked to the decreased abundance of mixotrophic testate amoebae under drier conditions (R2  = .4207; p < .001). Our study implies that if effective precipitation decreases in the future, the carbon uptake capacity of boreal bogs may be threatened.

Transfer of transuranium elements along the food chain lichen-reindeer-man - A review of investigations in Finnish Lapland

Following the atmospheric nuclear tests in the '50s and early '60s radioecological research on the (sub)arctic food chain lichen-reindeer/caribou-man was initiated in Finland among other northern countries. The enrichment of radionuclides in this food chain can lead to exceptionally high body burdens among the indigenous Sami and Inuit populations consuming large quantities of the meat and edible organs of reindeer and caribou. In Finland, first fission and activation products and natural radionuclides were studied but in the early 1970s' the investigations concerning transuranium elements were started. These studies have continued to the present as also the effects of the Chernobyl accident on the existence of neptunium, plutonium, americium and curium isotopes in the environment of northern Finland have been investigated. In addition to radioactivity measurements detailed dietary surveys were performed among the reindeer herders and other Sami persons to assess the human intake of radionuclides by ingestion. The main aim of this literature review is to summarize the obtained data concerning transuranium elements in the food chain lichen-reindeer-man in northern Finland but also some supporting data is included.

Nuclear contamination sources in surface air of Finnish Lapland in 1965-2011 studied by means of 137Cs, 90Sr, and total beta activity

Radionuclides ¹³⁷Cs and ⁹⁰Sr and total beta activity were determined from air filters collected in Rovaniemi (Finnish Lapland) in 1965-2011. Nuclear contamination sources present in the air filter samples as well as temporal changes in radionuclide concentrations were examined. Ozone observations and meteorological modeling were used in combination with radionuclide analyses to study the reasons behind the observed seasonal concentration variation. In general, the magnitude and variation in activity concentrations of ¹³⁷Cs and ⁹⁰Sr and total beta activity in the surface air of Rovaniemi in 1965-2011 corresponded well with values from other countries. However, the obtained results prove in practice that hardly any refractory or intermediate radionuclides from the destroyed Chernobyl reactor fuel were introduced to Finnish Lapland. The main source of ¹³⁷Cs and ⁹⁰Sr and total beta activity in the surface air of Rovaniemi in 1965-2011 has been intense atmospheric nuclear weapon testing in 1950s-1960s and later tests performed in 1965-1980, as well as leakages from underground nuclear tests in Semipalatinsk, 1966, and Novaya Zemlya, 1987. For ¹³⁷Cs and total beta activity, the influence of Chernobyl and Fukushima accidents was detected.

Aerosol particle size distribution of atmospheric lead-210 in northern Finland

Size-segregated aerosol samples were collected with a high-volume 6-stage cascade impactor at Sodankylä, Finland, 100 km north of the Arctic Circle. The ²¹⁰Pb content of the samples were determined with radiochemical separation of in-grown ²¹⁰Po followed by alpha spectrometry. Most of the ²¹⁰Pb activity was incorporated in accumulation mode aerosol particles. The activity median aerodynamic diameter (AMAD) ranged from 0.53 μm to 0.98 μm 38-61 per cent of ²¹⁰Pb activity was found to be associated with aerosol particles smaller than 0.69 μm. A slight downward tendency of ²¹⁰Pb activity median aerodynamic diameter was observed as a function of increasing ²¹⁰Pb activity concentration. This is related to the continental origin of airborne ²¹⁰Pb on one hand, and various aerosol particle growth processes on the other hand. Also a clear tendency towards a higher ⁷Be/²¹⁰Pb activity ratio as a function of increasing aerosol particle diameter was observed. This, in turn, reflects the different origin of ²¹⁰Pb, exhalation of ²²²Rn from the soil into the air, and ⁷Be, formation by cosmic radiation in the upper troposphere and the stratosphere.

A simple model to estimate deposition based on a statistical reassessment of global fallout data

Atmospheric testing of nuclear weapons began in 1945 and largely ceased in 1963. Monitoring of the resulting global fallout was carried out globally by the Environmental Measurements Laboratory and the UK Atomic Energy Research Establishment as well as at national level by some countries. A correlation was identified between fallout deposition and precipitation and an uneven distribution with latitude. In this study, the available data from 1954 to 1976 for (90)Sr and (137)Cs were reanalysed using analysis of covariance (ANCOVA) and logarithmically transformed values of the monthly deposition density as the response variable. Generalized additive models (GAM) were used to explore the relationship of different variables to the response variable and quantify the explanatory power that could be achieved. The explanatory variables which consistently explained most of the variability were precipitation at each site, latitude and change with time and a simple linear model was produced with similar explanatory power as the GAM. The estimates improved as the temporal resolution of the precipitation data increased. A good log-log fit could be obtained if a bias of about 1-6 mm precipitation per month was added, this could be interpreted as dry deposition which is not otherwise accounted for in the model. The deposition rate could then be explained as a simple non-linear power function of the precipitation rate (r(0.2-0.6) depending on latitude band). A similar non-linear power function relationship has been the outcome of some studies linking wash-out and rain-out coefficients with rain intensity. Our results showed that the precipitation rate was an important parameter, not just the total amount. The simple model presented here allows the recreation of the deposition history at a site, allowing comparison with time series of activity concentrations for different environmental compartments, which is important for model validation.

Airborne fission products in the High Arctic after the Fukushima nuclear accident

High-volume aerosol samples were collected at the Mt. Zeppelin Global Atmosphere Watch station, Ny-Ålesund, Svalbard (78°58'N, 11°53'E). The samples were analysed to find out if the radionuclide emissions from the Fukushima nuclear power plant accident in March 2011 could be detected also in the atmosphere of the High Arctic. Iodine-131 and (134)Cs and (137)Cs were observed from 25 March 2011 onwards. The maximum (131)I, (134)Cs and (137)Cs activity concentrations were 810 ± 20, 659 ± 13, and 675 ± 7 μBq/m(3), respectively. The comparison between the measured (131)I activity concentrations at Mt. Zeppelin and those calculated with the SILAM dispersion model revealed that the timing of plume movements could be rather well predicted with the model. The activity concentration levels between the measurements and the model calculations deviated. This can be due to the inaccuracies in the source term. The (134)Cs:(137)Cs activity ratio recorded in Svalbard was high compared to earlier incidents. The ratio was close to 1 which is in agreement with other studies of the Fukushima releases. This distinctive activity ratio in the Fukushima debris could be used as a tracer in Arctic radioecology studies if the activity concentrations are high enough to be detected.

240Pu/239Pu mass ratio in environmental samples in Finland

The (240)Pu/(239)Pu mass ratio was determined with SF-ICP-MS in lichen, peat, grass, air filter, and hot particle samples obtained in Finland. The main part of the air filters were sampled in northern Finland in 1963, whereas all the other samples were collected in southern and central Finland immediately after the Chernobyl accident in 1986. The (240)Pu/(239)Pu mass ratio varied between 0.13 ± 0.01 and 0.53 ± 0.03 in the environmental samples analyzed. The values for the (240)Pu/(239)Pu ratio confirm previous estimations, based on the (238)Pu/(239+240)Pu alpha activity ratio in the same samples, that global fallout from nuclear weapons testing and deposition from the Chernobyl accident have been the main Pu contamination sources in the environment in Finland.

Total beta activity, 137Cs and 90Sr in surface air in northern Finland in 1963

Air filter samples collected at Sodankylä (67º22´ N, 26º39´ E) were analyzed to determine concentrations of 137Cs and 90Sr in surface air in northern Finland in 1963. Previously, activity concentrations of Pu isotopes have been determined from the same filters. Activity concentrations of 137Cs and 90Sr in surface air were <50 μBq/m3–13800 ± 2700 μBq/m3 and <10 μBq/m3–5340 ± 290 μBq/m3, respectively. Air concentrations of 137Cs and 90Sr varied seasonally with a maximum in spring due to the springtime enhanced transportation of air masses with radioactive aerosols from the stratosphere to the troposphere. Activity ratios 90Sr/239+240Pu and 90Sr/137Cs were 6.9 ± 0.8–75 ± 5 and 0.08 ± 0.03–1.46 ± 0.51, respectively. The median value for the 90Sr/137Cs ratio (0.508) indicates contamination from global nuclear test fallout. An air mass back trajectory analysis suggests that no direct transport of radioactivity from the Novaya Zemlya test site to northern Finland occurred in 1963.

Speciation of ¹²⁹I in sea, lake and rain waters

Concentrations of the very long-lived fission product (129)I and stable iodine ((127)I) in the Baltic Sea and lake and rain waters from Finland, were measured as well as their occurrence as iodide (I(-)) and iodate (IO(3)(-)). The highest concentrations of both (127)I and (129)I occurred in sea water, on average 11.1 ± 4.3 μg/l and 3.9 ± 4.1 × 10(-9) at/l. In rain and lake waters the concentration of (129)I was more or less identical and almost one order of magnitude lower than in sea water. Based on these observations, and data from the literature, it is assumed that the source of (129)I in lakes is precipitation and the major source in the Baltic Sea is the inflow of sea water from the North Sea through the Danish Straits. The concentration of (129)I in the Baltic Sea has increased by a factor of six during ten years from 1999. In all studied water types the main chemical form of both iodine isotopes was iodide; in sea and lake waters by 92-96% and in rain water by 75-88%. Compared to (127)I the fraction of iodide was slightly higher in case of (129)I in all waters.

Overview of strontium-89,90 deposition measurements in Finland 1963-2005

In Finland the deposition of strontium-89 (90Sr) and strontium-90 (90Sr) has been monitored since the early 1960s. The measured cumulative 90Sr deposition in 1963-2005 is on average 1200 Bq m(-2), of which 150 Bq m(-2) originates from the Chernobyl accident. Adding to this the deposition in 1945-1962 produces a value of 2040 Bq m(-2) for the cumulative deposition in Finland. The nuclear explosion-derived deposition up to 1985 obtained in this study, 1850 Bq m(-2), is in good agreement with the zonal 90Sr deposition of 1740 Bq m(-2) in the 60 degrees N-70 degrees N latitude band estimated by UNSCEAR. The regional deposition patterns of 89Sr and 90Sr following the Chernobyl accident resemble those of the refractory nuclides such as 239,240Pu and 95Zr. The total deposition of Chernobyl-derived 90Sr in Finland was about 5.3 x 10(13) Bq. This activity corresponds to 0.027% of the reactor core inventory and 0.66% of the atmospheric emissions from the accident. The corresponding figures for 89Sr are 4.5 x 10(14) Bq, 0.023% and 0.56%, respectively.

Heavy metals in bottom sediments of Lake Umbozero in Murmansk Region, Russia

Sediment cores collected from different locations of Lake Umbozero were studied with respect to concentration and mobility of trace and heavy metals Co, Cu, Fe, Mn, Ni, Pb, U, and Zn. Lake Umbozero is the second largest lake in the Murmansk Region and subjected to contamination by air-borne emissions and river transportation from the nearby metallurgical and mining industries. Unlike its neighboring, more industry-prone Lake Imandra, Lake Umbozero is relatively unexplored with respect to its state of pollution. In our study, metal distribution in sediments was found to vary with respect to the cores, although in general the concentrations were at the same level throughout the lake indicating uniform horizontal distribution of metals. When compared to Lake Imandra, the concentrations of most of the metals studied were significantly lower and represented the levels in sediments measured in lakes of Kola Peninsula located further off from industrial pollutant sources. An exception was Pb the concentration of which was at the same level as in Lake Imandra, probably due to long-distance transport. Sediment layers were subjected to four-step sequential extraction procedure to reveal the metal distribution in soluble, exchangeable, acid-soluble, and residual fractions. Indicative of their potential higher lability, Mn, U, and Zn were generally found in exchangeable fraction; as also Mn and U extensively in the acid-soluble fraction.

Americium and curium deposition in Finland from the Chernobyl accident

241Am and 244Cm were analysed from peat samples collected in Finland immediately after the Chernobyl accident. The separation method included co-precipitation, anion exchange and extraction chromatography. Activities of 241Am and 244Cm were measured by alpha spectrometry. The activity of Chernobyl-derived 241Am varied between 0.0115 and 9.32 Bq/m2 and that of 244Cm from < 0.002 to 1.97 Bq/m2 (reference date 1.5.1986). The origin of 241Am in Finland is predominantly from atmospheric nuclear tests. However, the geographical distribution of Chernobyl-americium is uneven and depending on a location even 100% of 241Am in peat originated from the Chernobyl accident. The deposition pattern of Chernobyl-derived 241Am and 244Cm resembles that of other refractory nuclides, such as 95Zr, 141Ce and 239,240Pu.

Deposition of gamma emitters from Chernobyl accident and their transfer in lichen-soil columns

Lichen-soil column samples were taken from several locations in the Southern Finland between 1986 and 2006. Columns were divided into three parts, upper lichen, lower lichen and underlying soil, and their gamma emitting radionuclides, 134Cs, 137Cs, 103Ru, 95Zr, 106Ru, 110mAg, 125Sb and 144Ce, were measured with gamma spectrometry. Deposition values were calculated as Bq/m2 for each sampling site. Distribution of various radionuclides in the three compartments as a function of time was determined. Both effective and ecological half-lives of all radionuclides were calculated for upper lichen, whole lichen and whole lichen-soil column. A linear relation was derived between the physical half-lives and effective half-lives for whole lichen and for whole lichen-soil column. Reindeer meat activity concentrations of various radionuclides and ensuing radiation doses to reindeer-herding people were also estimated for a hypothetical case where a similar high radioactive pollution, as was taken place in the Southern Finland, would have occurred in the reindeer-herding areas in the Finnish Lapland.

Plutonium in the air in Kurchatov, Kazakhstan

Weekly air samples of 25000 m(3) volume were taken with two air samplers over a period of one year in 2000-2001 in the town of Kurchatov in Kazakhstan. For another three-month period in 2001, the samplers were run in the city of Astana, about 500 km west of Kurchatov. (137)Cs, Pu and U concentrations were determined from the filters. Pu activities in Kurchatov varied in a 100-fold range; median (239,240)Pu activities were 100 nBq/m(3) and (238)Pu activities 34 nBq/m(3). The corresponding values for Astana were considerably lower: 29 and 9 nBq/m(3), respectively, and in half of the filters the (238)Pu activity was below the detection limit. Plutonium concentration correlated with the amount of dust retained on the filters only at the highest dust loads. Also no correlation between wind speed and the plutonium activity in the filters was observed. Thus, resuspension does not seem to be the mechanism responsible for the airborne plutonium. No clear seasonal variation of Pu air concentration was observed, though levels were somewhat elevated in February to April. There was no correlation between the plutonium and (137)Cs concentrations. In most of the filters the cesium concentration was below the detection limit, but in those filters where it could be detected the cesium concentration was practically constant at 3.9+/-1.6 microBq/m(3). Dose estimation for the inhalation of the airborne plutonium gave a low value of 0.018 microSv/a for the inhabitants in Kurchatov, which is about a thousand times lower than the dose caused by the naturally occurring (210)Po. Air parcel trajectory analysis indicated that the observed Pu activities in the air could not unambiguously be attributed to the most contaminated areas at the Semipalatinsk Test Site.

Identification of organic compounds in atmospheric aerosol particles by on-line supercritical fluid extraction–liquid chromatography–gas chromatography–mass spectrometry

Atmospheric particles were collected with a high-volume sampling system at an urban site in Helsinki (Finland). The samples were analysed by on-line coupled supercritical fluid extraction-liquid chromatography-gas chromatography-mass spectrometry (SFE-LC-GC-MS). The aerosol sample was first extracted by SFE. The extract was then transferred to a liquid chromatograph where it was fractionated into four fractions according to polarity. Each fraction from the liquid chromatograph was transferred to a gas chromatograph by large-volume injection, where final separation was carried out. The first LC fraction (280 microl) contained nonpolar compounds, such as n-alkanes, hopanes and steranes. The second fraction (840 microl) included polycyclic aromatic hydrocarbons (PAHs) and alkyl-PAHs, while the third and fourth fractions (840 microl each) contained more polar compounds, such as n-alkan-2-ones, n-alkanals, oxy-PAHs and quinones.

Ambient silver concentration anomaly in the Finnish Arctic lower atmosphere

Mean silver concentrations in weekly particle samples collected at Kevo, northern Finland, were determined for the period of October 1964-March 1978 by neutron activation analysis. Two distinct periods were observed in the silver concentration levels over this time frame. During 1964-1970, mean weekly silver concentration levels were found in the range of 0.01-190 ng/m3 with an arithmetic mean of 2.19 ng/m3. A few very high silver concentration levels (>10 ng/m3) were observed in this period, some of which simultaneously occurred with some of the highest bromine and iodine concentration levels. During 1971-1978, silver concentration levels were in the range of 0.02-0.89 ng/m3 with a mean value of 0.09 ng/m3. The observed concentration levels in the later period matched well the data from the early 1990s reported at Sevettijärvi, northern Finland, about 60 km east of Kevo. Data analysis, historical records for this region, and residence time analysis (RTA) using wind back-trajectories show that occasional smelting of silver-rich Norilsk ores at the Nikel smelter, Kola Peninsula, was probably a significant contributor to elevated mean silver concentration levels during 1964-1970. RTA alone was not able to unambiguously identify the most probable source region for highest silver impacts at Kevo due to the weekly integrated nature of the samples collected. Critical examination of wind back-trajectories (24 per day) for specific high silver, bromine, and iodine concentration weeks was carried out to supplement the ensemble RTA analysis (2 back-trajectories per day). The supplemental back-trajectory analysis revealed that deposition of the smelter component silver as well as the sea components (bromine and iodine) could occur together at Kevo during these weekly sampling periods. The study implies that data from weekly integrated samples are insufficiently time-resolved for RTA methods alone to unambiguously resolve the sources contributing to ambient atmospheric concentrations at Kevo, Finland.

Source areas of airborne 7Be and 210Pb measured in Northern Finland

Daily aerosol samples were collected at Sodankylä, Northern Finland, from July 1995 to June 1997. The filter samples were analyzed for 7Be by semiconductor gamma spectrometry and for 210Pb by alpha counting of the in-grown 210Po. The concentrations were lognormally distributed with median concentrations of 2,500 and 160 muBq m(-3) for 7Be and 210Pb, respectively. The trajectory analysis performed showed that the highest 210Pb activity concentrations were associated with continental air masses originating in Central Russia. High 7Be activity concentrations were found in air masses from Central Russia and, during springtime, also in air masses coming from southwest. The latter cases were attributed to the transfer of stratospheric air masses into the troposphere along the polar front. Slightly elevated 7Be and 210Pb concentrations were found in air masses coming to Sodankyla from northwest between 70th and 80th latitudes. This was attributed to the long-range transport from continental North America.