^fi QcnmiH Siv*
STUK-A75
April 1990
AIRBORNE AND DEPOSITED RADIOACTIVITY IN FINLAND IN 1987
Supplement 1 to Annual Report STUK-A74
Hannele Aaltonen, Ritva Saxen and Tarja K. Ikäheimonen STvK- h-- >C
STUK-A75 April 1990
AIRBORNE AND DEPOSITED RADIOACTIVITY IN FINLAND IN 1987
Supplement 1 to Annual Report STUK-A74
Hannele Aaltonen, Ritva Sax6n and Tarja K. Ikäheimonen
Finnish Centre for Radiation and Nuclear Safety P.O.Box 268, SF-00101 HELSINKI FINLAND fS3N951-47-146e-0 ISSN 0781-1705
Helsinki 1990 The Finnish Government Printing Centre 3Ai
ABSTRACT
The Finnish Centre for Radiation and Nuclear Safety has con tinued its nationwide monitoring of airborne and deposited radioactive substances ir, Finland.
In the air surveillance programme concentrations of artificial radionuclides are monitored in the air close to the ground. In 1987, air dust samples were collected in Nurmijärvi, 40 km north of Helsinki and in Rovaniemi. When necessary, sampling was also launched in Helsinki.
Several radionuclides originating from the accident in Chernobyl in 1987 could still be detected in air dust samples. The con centrations of the prevailing nuclides 134Cs and 137Cs were stable and there was no significant difference between winter and summer. Fresh fission nuclides were detected in March and August.
A sharp decrease in the amounts of radioactive substances de posited was noted at all the 18 sampling stations as against 1986. The total annual amounts of deposited 137Cs varied at different stations in 1987 from 7.7 Bq/m2 (Rovaniemi) to 1500 Bq/m2 (Kauhava) and those of »° Sr in 1986 from 4.7 Eq/m2 (Tai valkoski) to 590 Bq/m2 (Kuhmo) and in 1987 from 1.4 Bq/m2 (Iva lo) to 38 Bq/m2 (Kuhmo). The total annual amounts of 236 Pu and 2 2 3 9,240Pu were 3rl and i2 mBq/m in Nurmijärvi and 3.4 and 14 mBq/m2 and Lappeenranta in 1987, respectively.
In 1987, resuspension of radionuclides was characteristic cf the deposition situation. Due to this phenomenon, unexpectedly high contents of deposited radlocesium occurred occasionally in the samples, though the discharge caused by the Chernobyl accident lasted for only a short period in spring 1986. The proportion of 137Cs originating from Chernobyl in 1987 varied from 3% to about 40% of the corresponding amounts in 1986 at different stations. The corresponding percentages for 90Sr varied from 1.6% to 34%. It CONTENTS ABSTRACT 3 CONTENTS 5
1 INTRODUCTION 7
2 MATERIAL AND METHODS 8 2.1 Sampling 8 2.1.1 Airborne dust at ground level 8 2.1.2 Deposition 8 2.2 Pre-treatment of samples 10 2.2.1 Air 10 2.2.2 Deposition 10 2.3 Analysis methods 11 2.3.1 Gammaspectrometric analyses 11 2.3.2 Strontium analyses 12 2.3.3 Analyses of transuranic elements 12 2.3.4 Tritium analyses 12
3 RESULTS 12 3.1 Ground-level air 13 3.1.1 The occurrence of fresh fission products ^3 3.1.2 Chernobyl fallout 15 3.2 Deposited radioactivity 18 3.2.1 Gamma-emitting radionuclides 18 3.2.2 90Sr 21 3.2.3 137Cs/»°Sr in deposition 21 3.2.4 Transuranic elements 21 3.2.5 Tritium 24
4 DISCUSSION 25 4.1 Resuspension 25 4.2 Accumulated deposition 27
ACKNOWLEDGEMENTS 28 REFERENCES 29 TABLES 32 7
1 INTRODUCTION
The Finnish Centre for Radiation and Nuclear Safety has con tinued its nationwide programme to monitor both airborne and deposited radioactivity in 1987."••
Airborne dust was collected continuously in Nurmijärvi and Rovaniemi. When necessary, airborne dust sampling was also launched in Helsinki. All samples were analysed gammaspectro- metricly.
Continuous sampling at the 18 stations was carried out on a monthly basis to determine the amounts of radioactive substances deposited in different parts of the country.
The samples were analysed both for gamma-emitting radionuclides and for /3-emitting 89Sr and 90Sr. Al fa-emitting transuranic elements were determined in samples from Nurmijärvi, where we have three differ*.nt sample collectors, and on temporally com bined samples from Lappeenranta. Pour stations also collected deposition for tritium determinations. This report includes results for 1987 as well as the results for 90Sr and transuranic elements in the 1986 deposition which were not included in the previous report0. 8
2 MATERIAL AND METHODS
2.1 Sampling
2.1.1 Airborne dust at ground level
In Nurmijärvi, 40 km north of Helsinki, airborne dust is col lected on a glass fibre filter. The air flow rate through the glass fibre filter in Nurmijärvi is about 750 m3/h which corre sponds to a face velocity of 0.9 m/s. In Rovaniemi, northern Finland, airborne dust was collected up to the beginning of October using a portable sampler (STAPLEX*) the capacity of which is about 100 m3/h. Since October, a transportable sampler with a capacity of 150 m3/h has been used. In Helsinki, an air sampling system was launched for special reasons, using a sampler with a capacity of about 150 m3/h. The locations of the sampling stations are shown in Figure 1.
Airborne dust is collected on a glass fibre filter, type Whatman GF/A, and normally the filters are changed twice a week to avoid overloading and to ensure a high retention of particulate nu clides. When necessai/, the filters are changed more often. The Nurmijärvi sampler is also equipped to collect gaseous fractions of iodine. Some of the air that has passed the glass fibre filter is sucked through activated carbon impregnated with potassium iodide, type SS 207B-1.5 KI 8-12 mesh. The air flow rate through the carbon bed is adjusted to a maximum of about 12 m3/h, corresponding to the residence time of 0.2 s in the carbon bed, to ensure a very high retention of iodine, even in the form of methyl iodide. If nothing unusual is detected in analyses of the glass fibre filters, the charcoal filter is changed once a month.
2.1.2 Deposition
Wet and dry deposition was monitored continuously at 18 sta tions. The surface areas of the samplers are 0.05, 0.07 or 1 m2. The sample collectors are made of stainless steel or 9
Fig. 1. Sampling stations collecting continuously airborne radioactivity (•). Samples were analysed gammaspectro- metricly. Sampling stations for deposition samples and deter minations made on the samples from different stations: • gamma-emitting radionuclides and radiostrontiurn A tritijm • transuranic elements
1 Nurmijärvi 10 Kauhava 2 Mariehamn 11 Kuopio 3 Jokioinen 12 Kuhmo 4 Niinisalo 13 Kajaani 5 Lappeenranta 14 Taivalkoski 6 Savonlinna 15 Rovaniemi 7 Jyväskylä 16 Sodankylä 8 Joensuu 17 Ivalo 9 Vaasa 18 Inari 10 brass. Samples from the steel collectors are used to analyse gamma-emitting radionuclides, strontium and transuranic iso topes, and those from the brass collectors for tritium determi nations. At two stations. Nurmijärvi and Lappeenranta, there are two stainless steel samplers, with surface areas of 0.05 and 1 m2 . Samples from the big collector in Nurmijärvi and Lappeenranta were used for transuranic element determinations. The collectors were usually emptied at the end of each month. The stainless steel collectors were rinsed with dilute nitric acid 2nd distilled water after every emptying to prevent adsorp tion of radionuclides onto the walls of the samplers. The rins ing solutions were added to the sample. The brass samplers were not rinsed with th<3 acid solution. All the sampling sta tions are shown in Fig. 1.
2.2 Pre-treatment of samples
2.2.1 Air dust samples
After sampling, the glass fibre filters changed on Monday and Thursday were combined to form a week sample. The filters were pulverized by compressing, and the powder was homogenized and re-pressed onto discs to provide a suitable counting geometry for gammaspectrometric analysis. The activated charcoal was measured without any pre-treatment in a Marinelli-beaker (0.5 litre).
2.2.2 Deposition samples
Known amounts (10-20 mg) of Sr, Cs, Ba and Ce carriers were added to the deposition samples used to analyse gamma-emitting radionuclides and radiostrontium, and the samples were acidified with nitric acid on arrival at the laboratory. The samples were concentrated by evaporating them and ashing the dried residue at 450 °C. Radiochemical " Sr and 90 Sr analyses were performed on the ashed samples after the gammaspectrometric analyses. The monthly samples were not analysed separately for strontium isotopes, but those from certain stations were combined quaiter- 11 ly before the radiostrontium analyses. Samples from the stations with the lowest deposition were combined every half year to get the total amounts of ,0 Sr deposited at these stations.
Samples from the 1 m2 collectors, used to analyse transuranic elements were also evaporated and ashed. If the monthly samples vrere combined temporally, this was done after ashing. The sam ples were then dissolved in 8 M nitric acid. 242Pu and 243Am tracers were added to tha samples and they were mixed overnight. After filtration with glass fibre filters the remaining residues were wet ashed with nitric and hydrochloric acids. After filtra tion these acid-leached parts of the samples were evaporated, dissolved in 8 M nitric acid and combined with the rest of the sample.
2.3 Analysis methods
2.3.1 Gammaspectrometric analyses
Three spectrometry systems were used for airdust and deposition samples. The relative efficiency of the detectors varies between 30% and 39%. The smallest detector is lithium drifted germanium crystal, the others being high purity germanium crystals. The detectors are placed in background shields made of 12-14 cm thick lead rings which are gradually linod with cadmium (1 mm) end copper (0.5 mm) to reduce the effect of X-rays. The energy range analysed is from 30 keV to 2700 keV.
The measuring time varies according to the type of sample. The combined glass fibre filters were usually analysed over the weekend and the charcoal and deposition samples overnight.
The radioactivity concentrations in the samples were calculated using the computer program GAMMA-83.910 The calibrations of the detectors are described elsewhere.15 12
2.3.2 Strontium analyses
Radiostrontium was determined with a method presented by Osmond et al, with slight modifications for rain water 7. Measurements were made as before, using a low-background beta-counter, the Berthold LB 770-1.8
2.3.3 Analyses of transuranic elements
Analysis of ^ransuranic elements was based on sereval ion ex changes and precipitations.16 Measurements were made using a silicon surface barrier semiconductor or p^ssivated implanted silicon detectors and a multichannel pulse weight analyzer. Internal tracers 242Pu and 243Am were used for yield determi nations.
2.3.4 Tiltiun analyses
For tritium analyses the samples from the brass collectors were distilled to dryness. Tritium was then determined using the electrolytic enrichment method presented by östlund et al.20 with some modifications.
3 RESULTS
The results for airborne and deposited radioactivity in Finland in 1987 are given in Tables I - XXIII. The activity concentra tions were calculated to the median of the sampling period.
The tables give the measurement errors in brackets after the re sults to describe the reliability of the detection. The error is given as percentages and includes the statistical error together with the calibration error of the analysing system. For gammaspectrometric analysing systems the calibration error is less than 4%. The error caused by sampling and sample pre- treatment is not included. The error in evaluation of the air volume through the sampler is estimated to be 5%. 13
The detection limit depends, among other things, on the sample volume, measurement time and nuclide. The detection limits may vary from one measurement to another. Typically, the minimum detectable activity in air samples is 0.1-10 ^Bq/m3 and 0.5-2 Bq/ra2 for deposition samples, depending on the nuclide.
3.1 Ground-level air
The radionuclide concentrations in ground-ierel air in Nurmijär vi, Rovaniemi and Helsinki are given in Tables I-III. The iodine results for Nurmijärvi are the sums of particulate and gaseous forms of iodine; for Rovaniemi and Helsinki, only the aerosol concentrations of iodine are given.
3.1.1 The occurrence of fresh fission products in 1987
In 1987 fresh fission products were detected in March and Au gust.
In March U1I was detected in both southern and northern Fin land. No other short-lived fission products were detected. Observations of iodine were made throughout northern and central Europe.5-61218 In Finland, the maximum value of particulate iodine (62 /nBq/m3 ) was measured in Helsinki during the collec tion period March 12-13. The source of this iodine was probably a nuclear power station.1219
In August, 131I was again detected in Northern Europe and other short-lived nuclides were also observed in Finland.1-4 Besides the results shown in Tables I - III, 132Te was detected in Nurmijärvi during the collection periods August 10-13 and 13-14; the concentrations were 5.7 ^Bg/m3 + 8% and 1.7 nBc/m* + 13%, respectively. In Rovaniemi, "Mo (17.1 /zBq/m3 + 8%), 103Ru (6.3 vBq/m? + 10%) and 1331 (530 /jBq/m3 + 6%) were detected during the sampling period August 6-10. In Helsinki, 133Te (10.6 fxBq/m3 + 8%) was also observed during the sampling period August 12-14. The meteorological conditions and the nuclide ratios showed that the source of this fresh fallout was most 14
probably leakage from a Soviet underground nuclear weapon test explosion performed in Novaya Zemlya on August 2, j.987.1-4
During the events in March and August *3 xI was also measured from the charcoal samples (Table IV). Besides iodine, no other nuclide was detected in the charcoal- The penetration of 131I through the glass fibre filter was ^4-82% in March and 90-97% in August. The iodine concentration measured from the charcoal sample collected between March 16 and 23 was close to the detec tion limit and increases the uncertainty of the figure for gaseous fraction. However, the penetration of iodine through the glass fibre filter was about the same as it was in spring and summer 1986. Figure 2 shows both the particulate and the total concentration of 131 I in Nurmijärvi in 198' 1987.
10*
10 TOTAL .IIIIUIilMI.il
10
10
10
10
10 10 ft 10
10"
10" J I L. J l_ JAN HAS HAY JUL SEP NOV JAN AAfl HAY JUL SEP 1986 1967
Fig- 2. Concentration of 131 I (,uBq/m3 ) in ground-level air in Nurmijärvi, 1986-1987. 15
3.1.2 Chernobyl fallout
Nine different gamma-emitting radionuclides originating from the Chernobyl accident were detected in air dust samples in 1987. Towards the end of the year observations of 110mAg, ia5Sb, and 106Ru became more rare and 103Ru was only detected during the first quarter of the year. 95 Zr, *5 Nb and 144 Ce were occa sionally detected throughout the year. The prevailing radio nuclides detected in all the samples were l37 Cs and 134 Cs (Ta bles I - 111).
In Nurmijärvi, the 137Cs concentrations decreased very slowly throughout the year and there was no strong variation in values as there were in December 1986 (Fig. 3). The average concentra tion of 13 7 Cs in 1987 was about 30 /xBq/m3 . Figure 4 shows the monthly mean concentration of 137Cs in Nurmijärvi in 1968-1987. in Rovaniemi, the 137Cs concentrations were on average lower than in Nurmijärvi. In November and December, strong variations in cesium concentrations were detected. As no such variations were observed during the same period either in neighbouring countries or in Finland the source was local. The ratios between 134Cs and 137Cs showed that the nuclides originated from the Chernobyl accident. The most probable cause is radioactive material resuspended from the sampler itself or from the sur roundings of the sampler.
The ratios of 134Cs to 137Cs detected in air dust samples in Nurmijärvi, including the results for all samples from April 28, 1986, up to end of 1987, are shown in Figure 5. A curve which corresponds to the radioactive decay of both cesium nu clides has been fitted to the data. According to this data the ratio between 134Cs and 137Cs at the end of April, 1986, was 0.57. All the cesium nuclide ratios measured fit in well with the curve when statistical error is taken into account. Thus, observed cesium nuclides originated from the Chernobyl accident and the proportion of old global fallout could not been distin guished. 16
AJBW 10
10
10
10
10
10
10
io: fl l J 10 '^ VW - ^vvtJUwTn 10"..H? ^ 10" J L. Jl I L J .' ' » ' I L. J l__l I I I I L. JÄN SÄfi SAY JUL SEP NOV JÄNSÄÄ NÄY JUL SEP NOV 1986 1981 Fig. 3. Concentration of 137Cs (^Bq/m3) in ground-level air in Nurmijärvi, 1986-1987.
1968 1910 1912 191* 1916 1919 1960 1982 1984 1986
Fig. 4. Monthly mean concentration of 137Cs (//Bq/m3 ) in ground- level air in Nurmijärvi, 1968-1987. 17
1.00
0.90L
0.80
O.lö
0.10
0.00 J I L ' • • ' i I i i i t i i ( | i ' • AT* MAT JIM JULAUSKPOCTNOVKCJIMiPanMAntrHrJUNJULAUDKPOCrHOVOCC 1986 1987
Fig. 5. The i34cs/i37 QB ratios in air dust samples in Nurmijär vi from April, 1986 to January, 1987. 18
3.2 Deposited radioactivity
3.2.1 Gamma-emitting radionuclides
A total of seven different gamma-emitting radionuclides - 95 Zr 106Ru, 110mAg, 125Sb, :,4Cs, 137Cs and 144Ce - were detected in the deposition samples. Towards the end of the year, observa tions of 110"Ag, 125Sb, 10*Ru and 144Ce became more rare. The prevailing radionuclides detected in all the samples were 137Cs and 134 Cs (Tables V - XVI). The monthly figures for 137 Cs show some peaks at different stations. One peak usually occurs in spring (March - May), when the maxima for stratospheric depo sition of 137Cs originating from nuclear weapon tests also occurred (Figs 6 and 7). The other peaks occur later, more or less irregularly, at different stations.
Sharp decreases in the total annual amounts of deposited radio nuclides was noted at all the stations in 1987, compared with those in 1986 (Fig. 8). The total amounts of 137Cs in 1987 varied from 7.7 (Rovaniemi) to 1500 Bq/m2 (Kauhava).
1961 1963 1965 1987 1969 1971 1973 1915 1977 1979 1981 1983 1985 1987
Fig. 6. Monthly depositions of 137Cs (Bq/m2 ) in 1961-1987. (in 19tl-85 mean of 17 stations, in 1986-87 Nurmijär vi). 19
Bq/ n Bq/i 10 10 JYVKSKYLK KUHMO 10 10
10 5 10
10 ^ 10
10 10 ^i_n„
10 ''•'' I i i i t i i i i i i i 10 • 11111 111111111111 VI JU. JM JUL 1986 1967
Bq/ m Bq/ m s 10 10 KUOPIO NIINISALO 10 10* "1 10 10* V 1 10 10* \\ \K 10 -JTJ 10* 10 M I I I I I I I ). I I I I 1 I I I.I,U1 10° ,JL LI ill L 1 L i L1..I.L1 1 JK* ""li" jm JUL 1986 1981 1986 1981
Bq/m* 10 NURMIJKRVI 10
10
10
10 k^
10 i m I i i i i 11 i i i i i i i i I i t i i i i i I i i H ' ' ' U ' ' W JUL JW JUL XC J/SJUL 1986 1981 1986 1981
Flg. 7. Monthly depositions of 137Cs (Bq/m2) in Jyväskylä, Kuhmo, Kuopio, tfiinisalo,Nurmijärv i and Sodankylä In 1986-1987. 30000
20000 _
70000 O
8 9 PLACE
Fig. 8. Total amounts of deposited 137 Cs at different sampling stations in 1987:
1 Nurmij ärvi 5 Lappeenranta 9 Vaasa 13 Kajaani 2 Mariehamn 6 Savonlinna 10 Kauhava 14 Taivalkoski 3 Jokioinen 7 Jyväskylä 11 Kuopio 4 Niinisalo 8 Joensuu 12 Kuhmo 15 Rovaniemi 16 Sodankylä 17 Ivalo 21
3.2.2 "ST
There were large differences in the quarterly, half-yearly and annual activity concentrations of ,0Sr at different stations (Tables XVII and XVIII and Fig. 9). Though the general trend after 1986 was a decrease, some peak values occurred more or less irregularly. The highest annual depositions of 90Sr were detected in Kuhmo and Niinisalo, being 590 and 420 Bg/m2 in 1986 and 38 and 32 Bq/m2 in 1987, respectively (Figs 1 and 10).
3.2.3 137Cs/*«>Sr in deposition
The ratio of total annual amounts of 137Cs to 90Sr in deposition varied from 2.6 to 67 at different stations, being lowest at Kuhmo and Kajaani (2.6 and 8.2, respectively). The variation in this ratio refers to the different areal distribution of these nuclides. 90Sr, a non-volatile nuclide, seems to follow the distribution of the other non-volatile nuclide 95 Zr.3 The same ratio varied from 8.3 to 114 in 1986. It thus decreased somewhat up to 1987 and differences between the stations were also small er than in 1986. On the other words, the amount of 90 Sr in the deposition was 0.19-12% and 1.5-38% of the amount of i:"Cs in 1986 and 1987 at different stations, the averages being 3.5% and 5.4%, respectively.
3.2.4 Transuranic elements
The amounts of transuranic elements were very low (Table XIX). There were also large variations in the amounts at different sampling periods. After May 1986, the amounts of 23sPu, 239- 240Pu and 241Am in Nurmijärvi varied from 0.72 to 3.0 mBq/m2 , from 0.77 to 7.8 mBq/m2 and from 0.1 to 3.5 mBq/m2 within a month, respectively. In 1987 the highest monthly amounts were 1.0, 4.5 and 4.9 mBq/m2, respectively. The highest 243Cm amount after May was 79 mBq/m2 (June 1986), and small amounts were still detected in June-July 1987. 243-24* cm amounts were below 1 mBq/m2 within a month. 22
Bq/m Bq/m j 10 3 10
JYVÄSKYLÄ z KUHMO 10 10 1
1 10 10 S 0 L-i 10 Lr 10 -1 10 10
-2 10 i i i t i i i r i i i I i i i i I i i i r I i 10 1 1 1i t i i i i I I 1 1 ! 1 1 1 1 ! 1 1 1 IN JUL ,'AN JUL JWN JUL JAN JUL 1986 1987 1986 1S87
Bq/m Bq/n 10 10
2 KUOPIO NIINISALO 10 10
1 10 10 V
0 10 10
-1 10 10
-2 10 M t I I I M i i t i i i i i i i i i i i 10 i i i i i i i i i i i i i i i i i i i i i i i M JUL JAM JUL 1986 198*7
Bq/ m 8q/«* 10 10
2 NURMIJÄRVI SODANKYLÄ 10 10
1 10 10
0 _r 10 _ 10
-1 10 10 X
-2 1 10 l ,l I f I I I I < i I i i i i i i i i i i i lo" ! j i i i i i t i i i i I i i i .1 1 JI I i I JAN JU. JAN JUL JAN JUL JAN ML 1986 1987 1986 1987
Fig. 9. Monthly (or quarterly or half-yearly) depositions of 90Sr (Bq/m*) in Jyväskylä, Kuhmo, Kuopio, Niinisalo, Nurnujärvi and Sodankylä in 1986-1987, Total amounts of deposited 90 Sr at different sampling stations in 1987:
1 Nurmij ärvi 5 Lappeenranta 9 Vaasa 13 Kajaani 2 Mariehamn 6 Savonlinna 10 Kauhava 14 Taivalkoski 3 Jokioinen 7 Jyväskylä 11 Kuopio 15 Rovaniemi 4 Niinisalo 8 Joensuu 12 Kuhmo 16 Sodankylä 17 Ivalo 24
The ratio 238Pu / 23«'»0Pu varied from 0.22 to 0.59 at Nurmijärvi in 1987 in the samples in which 238Pu could be detected. This means that plutonium isotopes still essentially originated from Chernobyl. 242Cm had the same origin. In the samples from Lap peenranta, the ratios were 0.30 and 0.11, also implying the par tial existence of Chernobyl fallout.
The total annual amounts of 238Pu and "»•24l)Pu in 1987 were 3.1 and 12 mBq/m2 in Nurmijärvi, being about 9% and 16% of those detected In 1986. In Lappeenranta the total annual amounts were 3.4 and 14 mBq/m2, respectively. The increasing total annual amount of 241 Am in relation to amounts of plutonium isotopes in Nurmijärvi is partially due to the decay of the dominant plu tonium isotope, 241 Pu, in Chernobyl fallout.
3.2.5 Tritium
The monthly activity concentrations of 3H in rain water at the four stations varied from 1.6 to 5.1 kBq/m3 ani from 1.0 to 4.5 kBq/m3 in 1986 and 1987, respectively (Table XX). Total annual depositions of 3H varied from 1.3 to 2.0 kB/m2 at the four sta tions in 1987, being almost the same r 3 in 1986 and 1985.13 Thus, no addition originating from Chernobyl could be observed. 25
4 DISCUSSION
4.1 Resuspension
When considering the possible source of cesium nuclides in air dust and deposition samples the alternatives are: stratospheric origin, local z««suspension and resuspension over a longer dis tance .
In Nurmijärvi, the 137 Cs concentration in air samples was very stable throughout the year. In neither Nurmijärvi nor Rovaniemi was there the spring maximum which was regularly detected before spring 1986. If a significant amount of cesium nuclides had reached the stratosphere during the Chernobyl accident there would have been an increase in concentrations in both places in spring.
In Nurmijärvi, there were also no major differencas In concen tration between summer and winter. As the ground is covered by snow in winter in Finland the resuspension of radioactive mate rial from the ground does not explain the winter values; on the contrary, there should be a decrease in concentrations. The Nurmijärvi sampler is located very close to pine and spruce forest. Ternovskij et al.17 have reported that, during the accident in the South Urals in 1957, 80-90% of the contamination was retained in the crowns of the trees; eight months after the accident the crowns of coniferous species still retained 40-50% of the initial radioactivity. The trees around the samplers could well have been a significant source of the radioactivity detected in the air samples.
The resuspension factor of 137Cs (air concentration/original deposition in 1986) In Nurmijärvi would be 4*10~9 nr1 in 1987 when the annual average air concentration is used.
A comparison of the total annual amounts of deposited radio- cesium detected in 1987 at different sampling stations with those detected in 1986 reveal that the amounts were still high- 26 est at the stations at which they were also highest in 1986. This indicates that most of the 137Cs was of local origin, being resuspended from the environment. If it had been of stratospher ic origin, it would have been distributed more evenly at the different sampling stations. The monthly depositions of 137Cs show occasional increases at different stations. Because these maxima occur irregularly they cannot be due to the stratospheric fallout, though a small fraction of the Chernobyl discharge may have gone into the stratosphere. The main origin of the radiocesium detected in deposition samples in 1987 was therefore resuspension from the environment of the samplers. The amount of old stratospheric 137Cs is in any case small compared with the amount discharged from Chernobyl.13
The maximum figures for monthly 137 Cs depositions at different stations do not correlate with the amounts of monthly precipi tation. Resuspension must therefore be due to some meterological reason other than precipitation, maybe to wind or storm. Conif erous trees in the immediate environment of the deposition sam plers may have been a significant source of radiocesium in the deposition samples.17
The proportion of 137Cs originating from Chernobyl in 1987 varied from sbout 3% to about 40% of the corresponding amounts in 1986 at different stations. Although the amount of old global fallout is small at most stations, it has been taken into ac count in calculations. The percentages were highest at the sta tions in northern Finland which had the lowest amounts of depo sited 137Cs in 1986. At these stations, the amount of Chernobyl- origin 137Cs in 1987 varied between 20-40% of the corresponding amounts in 1986. In Mariehamn, where the 137Cs deposition was about 850 Bq/m2 in 1986, the proportion was only 10%. At the other nine stations the amount of 13 7 Cs originated from Cherno byl in 1987 was 3.9 + 1.3 % of the total amount in 1986 at each station (Table XXI).
Resuspension was also noted in the results for 90Sr. The highest activity concentrations of 90Sr were found at the stations with 27 the highest concentrations in 1986, too (Kuhmo and Niinisalo). The amount of 90 Sr detected in 1987 compared with that in 1986 was highest in Taivalkoski (34%) and other stacions in northern Finland, where the total deposition of 90Sr was lowest in 1986. At the other stations the amounts of 90Sr deposited in 1987 were 3-10% of the respective values in 1986, «»part from Marie- hamn, where the amount in 1987 was only 1.6 % of the 1986 value. This may be because of the special geographic location of this station (Fiq. 1.).
It Is possible that the nuclides detected in air dust and depo sition samples have transported by wind or storm from farther away than the vicinities of the samplers, but from these results it is impossible to define the role of such resuspension. Local circumstances may also differ a great deal causing the radionu clides to behave differently.
4.2 Accumulated deposition
Calculation of the true accumulated deposition is difficult, due to the varying amounts of resuspended material. When calculating accumulated depositions at different stations it is not enough to distinguish the proportion of resuspension; the amount of local resuspension should also be known. The figures in Table XXIII give an accumulated deposition calculated as if no resus pension had occurred. At the stations studied, the accumulated amounts of 137Cs varied from ]900 to 35000 Bq/m2 and those of 90Sr from 1100 to 1700 Bq/m2 at the end of 1987. The figures are therefore somewhat too high, because the amount of locally resuspended radionuclides should have been subtracted, while resuspended radionuclides from farther away must be considered as new deposition at each station. 28
ACKNOWLEDGEMENTS
We thank Ms. Maarit Keino, Ms. Riitta Kontro, Mr. Ari Rosenberg, Ms. Pirkkc Saira and Mr. Timo Ylhäinen for their diligent work on the sample treatment and gammaspectrometric and radiochemical analyses. 29
REFERENCES
1. Aaltonen H, Sinkko K, Rantavaara A, Savolainen A L and Hatakka J. Short-lived fission products in Finland in August 1987. Helsinki: Finnish Centre for Radiation and Nuclear Safety, Surveillance Department, 1987. Report STUK-B-VALO 50.
2. Arvela H, Blomqvist L, Lecnmel8 H, Savolainen AL, Sark- kula S. Environmental gamma radiation measurements in Finland and the influence of the meteorological condi tions after the Chernobyl accident in 1986. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1987. STUK-A65. Supplement 10 to Annual Report 1986 STUK- A55.
3. Arvela H, Markkanen M, Lemmela H and Blomqvist L. Environmental gamma radiation and fallout measurements in Finland, 1986-87. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1989. STUK-A76. Supple ment 2 to Annual Report STUK-A74.
4. Bjurman B, Vintersved I, De Geer L-E, Rudjord A L, Ugletveit F, Aaltonen H, Sinkko K, Rantavaara A, Niel sen S P, Aarkrog A and Kolb W. The detection of radio active material due to leakage following an underground nuclear explosion. Accepted for publication in Journal of Environmental Radioactivity.
5. Kolb Walter. Personal communication. Physlkalisch- Technische Bundesanstalt, Federal Republic of Germany.
6. Nielsen Sven Poul. Personal communication. Ristf Na tional Laboratory, Denmark.
7. Osmond RG, Owers MJ, Healy C, Mead AP. The determina tion of radioactivity due to caesium, strontium, barium 30 and cerium in waters and filters. AERE-R 2899. Harwell, 1959.
Saxen R, Taipale TK and Aaltonen H. Radioactivity of wet and dry deposition and soil in Finland after the Chernobyl accident in 1986. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1987. STUK-A57. Supplement 2 to Annual Report STUK-A55.
Sinkko K. Computer analysis for gamma-ray spectra in sample measurements. Licenciate Thesis, Department of Physics. Helsinki: University of Helsinki, 1981 (In Finnish).
Sinkko K, Aaltonen H. Calculation of the true coinci dence summing correction for different sample geomet ries in gamma-ray spectroscopy. Helsinki: Finnish Centre for Radiation and Nuclear Safety, Surveillance Department, 1985. STUK-B-VALO 40.
Sinkko K, Aaltonen H, Mustonen R, Taipale TK and Juuti lainen J. Airborne radioactivity in Finland after the Chernobyl accident 1986. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1987. STUK-A56. Supplement 1 to Annual Report 1986 STUK-A55.
Spridningen av I-131 over Sverige i mars 1987. En första rapport. FOA rapport, Stockholm, Sverige, 16 mars 1987.
Studies on environmental radioactivity in Finland 1984- 1985. Helsinki: Finnish Centre for Radiation and Nu clear Safety, 1987. Annual Report STUK-A54.
Studies on environmental radioactivity in Finland 1986. Helsinki: Finnish Centre for Radiation anci Nu clear Safety, 1987. Annual Report STUK-A55. 31
Studies on environmental radioactivity in Finland in 1987. Helsinki: Finnish Centre for Radiation and Nu clear Safety, 1990. STUK-A74.
Taipale TK, Tuomainen K. Radiochemical determination of plutonium and americium from seawater, sediment and biota samples. Helsinki: Finnish Centre for Ra diation and Nuclear Safety, Surveillance Department, 1985. Report STUK-B-VALO 26.
Ternovskij I A, Romanov G N, Fedorov E A, Taverovskij E N, Kholina Yu B. Radioactive cloud trace formation dynamics after the radiation accident in the South Urals in 1957: migration processes. International Symposium on Recovery Operations in the Event of a Nuclear Accident or Radiological Emergency. IAEA-SM- 316. Vienna, Austria, 6-10 November 1989.
Ugletveit Finn. Personal communication. National Insti tute of Radiation Hygiene, Norway.
Weiss W, Stockburger H, Sartorius H, Zahringer M. Beobachtungen erhöhter Werte der I-131 und Xe-133 Aktivitätskonzentration der Luft in Mitteleuropa (1. Märzhälfte 1987). Bundesamt fur Zivilschutz, Institut fur Atmosphärische Radioaktivität, Freiburg, Deutch- land.
Ostlund HG, Werner E. The electrolytic enrichment of tritium and deuterium for natural tritium measurements. In: Tritium in physical and biological sciences. Vien na: International Atomic Energy Agency, 1962; I: 95-104 Table I. Radionuclide concentrations in ground-level air in Nurmijärvi from December 29, 1986, to December 31, 1987 (/iBq/m3). Measurement error given in brackets.
95 95 103 106 lift» 125 131 13V 137. 144. Sampling period Be ZT Nb Ru RU A» Sb Cs C« Ce
29 12. _ 5.1. 1570 (5% • 0* 0 0.75 (11*) 8.1 (9*) 0.32 (21%) 1.05 (18*) 0 22.2 (5*) 48 (4* 0 5.1. - 12.1. 2140 {5* ) 0 25 (26%) 0 0 2.8 (18*) 0.14 (31%) 0.78 (20%) 0 12.7 (5%) 27.6 (4% 0 12.1. - 19.1. 2320 (5* t 0 0 0.43 (15*) 4.4 (13*) 0 0 0 9.1 (9*) 20.7 (4* 0 19.1. - 26.1. 1700 (5% 1 0 1.10 (9%) 0 5.9 (17*) 0.34 (28%) 1.6 (23%) 0 23.9 (5%) 52 (4% 2.4 (17%) 26.1. - 2.2. 1560 (5* 1 0.8 7 (11%) 2.80 (5%) 0.40 119*) 5.8 (12*) 0.45 (16*) 1.50 (14*) 0 22.2 (5%) 51 <4* 7.7 (7%) 2.2. - 9.2. 2550 (5% > 0 0.73 (9*) 0.30 (22*) 6.2 (11*) 0.31 (19%) 1.50 (15*) 0 18.5 (2%) 42 (4* 1.9 (21*) 9.2. - 16.2. 1470 (5* > 0 0 0.2S (24*) 6.3 (10*) 0.33 (21*) 1.15 (15*) 0 10.9 (5%) 25.1 (4* 0 lb.2. - 23.2. 1.830 (3* > 0 0.49 (10*) 0 4.9 (10*) 0.50 (11%) 1.80 (12*) 0 24.3 (1%) 55 (3* 0.96 (21*) 23.2. - 2.3. 2030 <34 > 0 0 0 2.0 (25*) 0.31 (19*) 1.40 (15%) 0 15.9 (2%) 36 (3% 0 2.3. - 9.3. 3000 <5% > 0 0 0 2.6 (18*) 0 0.85 (18*) (5*) 14.2 (5*) 34 (4% 0 Ul "' 9.3. - 12.3. 3700 (2% > 0 0 0 0 0 0 205 (2%) 7.3 (2*) 17.8 (3% 0 to 12.3. 0 - 16 3. 4000 (3* 0 0 0 0 0 0 < (4%) 7.9 (3*) 18.4 (4* 16.3. - 19.3. 4400 CS* 0 0 0 8.4 (13*) 0 0 (5%) 10.6 (5%) 24.2 14% 0 19.3. - 23.3. 2580 (3% 0 0.55 (13%) 0 4.8 (26*) 0 1.6 (25*) 12 (7%) 11.6 (2*) 27.5 <4t 3.1 (20*) 23.3. - *6.3. 1470 (3% 0 0 0 4.5 (17*) 0 0 0.42 (21%) 4.4 (3%) 10.4 (4% 0 26.3. - 30.3, 2110 <3*] 0 0 0 5.3 (12*) 0.16 (36%> 0 0 7.6 (2*) 17.6 (3* 0 30.3. - 6.4. 3400 (5* 0 0 0 3.5 (18*) 0 0 1.34 (14%) 7.5 (5%) 17.6 (4% 0 6.4. - 9.4, 3100 (3* 0 0 0 4.2 (26*) 0 0 0 18.4 (4*> 42 (4* 0 9.4. - 13.4. 7100 (3* 4.9 (7*) 128 (4%) 0 16.3 (9*) 0 2.4 (22%) 1.28 (24%) 16.5 (2%) 41 (2* 44 (4*) 13.4. - 20.4. 3700 13* 0.4 1 (21%) 1.12 (7*) 0.48 (1?*) 14.3 (6*) 0.69 (12*) 1.80 (12%) 0 31 (3%) 76 (3* 5.1 18%) 20.4. - 27.4. 4200 <3% 0. 71 (12%) 1.89 (b*) 0 4.1 (14*) 0.44 (20*) 0 0 11.8 (4%) 28.2 (3% 11.3 (5%) 27.4. - •*.5, 3400 <3*] 0 0 0 0 0 0 0 11.2 (4*) 27.1 (3* 1 0 4.5. - U.S. 3800 (3*1 0 0 0 2.7 (26%) 0 0 0 17.4 (4%) 42 (4% 0
below the detection limit
aerosols and other chemical Corns together Table I. corvt.
95 95 106 110a 125 131 134. 137_ 144_ Sampling period Be Zr Nb Ru Afl Sb Ca Ci Ce
a 11.5. 14.5. 1800 (3%) o 0 0 0 0 0 5.1 (6*) 12.9 (4*) 0 14.5. - 15.5. 2940 (3*) 0 0 0 0 0 0 10.8 (6*) 25.8 (4*) 0 15.5. - 18.5. 2490 (3*) 0 0 5.7 (15*) 0.3* (26*) 1.15 (26*) 0 15.6 (2*) 36 (3*) 2.2 (12*) 18.5. - 25.5. 3000 v3*) 0.22 (264) 0.49 (20*) 6.9 18*) 0.71 (11*) 1.80 (10*) 0 25.0 (3*) 61 (3*) 3.6 (9*) 25.5- - 1.6. 2920 (3%) 0 0 2.2 (29*) 0.27 (26*) 0 0 11.6 (2*) 29.4 (3*) 1.8 (26*) 1.6. - 8.6. 1860 (3%) 0 0 0 0 0 0 9.8 (4%) 24.7 (4%) 0 8.6. - 15.6. 2100 (3*) 0 0 7.7 (11*) 0.32 (30*) 0.64 (30*) 0 9.9 (2*) 25.6 (3*) 0 15.6. - 22.6. 2430 (3*) 0 0 6.4 (12*) 0.46 (24*) i.4 (22*) 0 14.1 (4*) 37 (3*) 0 22-6. - 29.6. 3200 (3*) 0 0 0 0.31 (28*) 0 0 11.9 (4*) 31 (4*) 0 29.6. - 6.7. 3100 (3*) 0 0.13 (25*) 2.7 (17*) 0.39 (16%) 0.93 (20*) 0 15.2 (3*) 40 (3*) 1.0 (28*) 6.7. - 13.7. 2380 (3*) 0 0 1.9 (20*) 0.49 (13*) 0.87 (17*) 0 2.3 (3*) 33 (3*) 0 13.7. - 20.7. 2870 (3*) 0 0 0 0 0 0 9.6 (4*) 25.2 (3*) 0 20.7. - 27.7. 3600 (3*) 0 0 2.4 (19*) 0 29 (19*) 0.66 (21*) 0 9.6 (4*) 25.1 (3*) 0 27.7. - 3.8. 1620 (3*) 0 0 0 0.26 (23*) 0.39 (24*) 0 8.0 (4*) 20.9 (3*) 0 3-8. - 6.8. 1980 (3*1 0 0 0 0 0 0 3.5 (4*) 10.2 (4*) 0 6.8. - 10.8. 1400 (3*) 0 0 0 0 0 0 8.0 (4*) 20.9 (3*) 0 10.8. - 10.8. 850 (5%) 0 0 0 0 0 0 9.3 (18*) 16.6 (4*> 0 b 10.8. - 13.8. 1820 (3*) 0 0 0 0 0 164 (5*) 10.9 (5*) 26.1 (4*) 0 13.e. - 17.8. 2800 (3%) 0 0 0 0 0 288 (4*) 10.6 (4*) 27.3 (4%) 0 17.8. - 20.8. 4300 (3%) 0 0 0 0 0 335b <4*> 8.6 (5*) 23.0 (4%) 0 b 20.8. - 24.8. 2270 (3%) 0 0 0 0 0 66 <11*> 5.0 (S*> 13.0 (4*) 0 b 24.8. - 27.8. 2400 (3*) 0 0 0 0 0 171 (5*) 8.2 (4*) 21.9 (3*) 0 27.8. - 31.8. 1830 (3%) 1.44 (12%) 3,0 (5*) 6.0 (17*) 0 1.34 (24*) 0.81 (21*) 10.9 (4*) 29.8 (4*) 22.2 (5*) 31.6. - 3.9. 1290 (3*) 0 0 0 0 0 0.43 (25*) 13.2 (4*) 34 (3*) 4.4 (12*)
below the detection limit aerosols and other chemical forms together 34
in o o o not O O rt O O O
nnnPinnnnnnnuinvNnnninin
« rs m N«t6t0rtto««rtrsAr«- ff» ov r»f»»i>tN^omfiiAf*kttpiotfDOt09»«o«>o rtrtrtlflrtNWrt«lrtrtrt(N rt N f» * rH
•**»fOM*'*»^W«»K- M*OMn»*(0 II v • »ooo.-tor-vors«inofNO«>«»rtui « oooooooooooo o o o o o o S S 5S OOOOOOOOOOOOOOOOrtOOO OP» H» *» _< Cl (M r4 H OOOOOOOOOOOOOOOOOOOO «*»*»*# o e> m m s » «e trv **<•>— H H — rt t-l 3 irtnrsrv rt • ^ •» s ooonoimraomoiftoriiooomooo O o f* •Jl oooooooooooooooooooo » oooooooooooooooooooo « rtnrtflflflflflrtnflujflnciHrtnflfl « oooooooooooooooooooo Mmrvvomoooö»*rt(NiNiiiinij«rtujvD i i«vCi^r s rtrtHH«n»»»IHrti4rtrt(1|l(rtHHH o »»»»OOOOrtHH-i-ilNINlvilNNNri & d«rtoö n i-irtrMrMirtM»j>M»kOnoin«»r^»pvm-i c H rt N rt H « H H IV n I I I I t I I I I I I I I I I I I I I I H »»»»jioqdortrtHrt'rifJfipifiiviy' movrts rtrtfMNinM^vtncrikPmomwrs^rkin rt» N rt n n H H IN H Table II. Radionuclide concentrations in ground-level air in Rovaniemi from January 23 to December 31, 1987 (/iBq/m3). Measurement error given In brackets. 106 132 131. 125 134 137 Saaplxog period Be Ru T* Sb C» Ca 23.1. - 9.2 2090 (2%) 0 0 0 0 1.» (15%) 4,8 (6%) 9.2. - 26.2 2300 (3%) 0 o 0 0 2.1 (20%) 4.3 (12*) 26.2. - 9.3 3400 (3%) 0 0 0 0 2.0 (7%) 3.6 (7*) 9.3. - 16.3 4600 (3%) 0 o 22.6 (6%) 0 6.1 (7%) 12.1 (6*) 16.3. - 23.3 4100 (3%) 0 0 5.7 (12%) 0 5.0 (8%) 11.9 (6*) 23.3. - 6.4 2650 (4*) 0 0 0 0 2.9 (9*) 7.0 (6*) b 6.4. - 23.4 23.4. - 30.4 4200 (4%) 0 0 0 0 2.9 (11*) 6.4 (9%) 30.4. - 7.5 3200 <4%) 0 0 0 0 5.0 (15*) 10.4 (7*) 7.5. - 14.5 2330 (4%) 0 0 0 0 0 3.3 (16*) CO 14.5. - 25.5 2520 (4%) 0 0 0 0 2.2 (17*) 5.5 (6%) en 25.5. - 8.6 «.6. - 22.6. 2540 (4*) 0 4.5 (10*) 11.6 (6*) 22.6. - 9.7 9.7. - 23.7 3700 (4%) 0 0 0 0 0 2.3 (14%) 23.7. . 30.7 2060 (4%) 0 0 0 0 0 3.6 (15%) 30.7. - 3.8 4100 (4%) 0 0 0 0 0 3.8 (15%) 3.8. - 6.8. 3700 (3%) 0 0 0 0 0 9.0 (24%) 6.8. - 10.8. 3700 (3%) 29 <22%) 300 (4*) 1880 (3%) 0 0 5.6 (16%) 10.8. - 11.8. 5800 (4%) 0 0 193 (5%) 0 0 10 (31%) 11.8. - 12.8. 4500 (5») 0 40 <11%) 190 (5%) 0 0 0 12.8. - 13.8. 1500 (5*) 0 0 70 (6%) 0 0 0 13.8. - 14.*. 1400 <6%) 0 0 88 (8t> 0 0 15 (33%) 14.8. - 17.8. 2100 (4%) 0 8. 8 (14*) 140 (4%) 0 0 6.1 (20%) a beJ.o w the det ection limit b no> t analysed MMMMfM U (O (O M M H *• VI OI-*©UlH-4*l-«»-J <-3 MMMMAlKfMKiH ^^»»©©©©tftftfvOtf»»»»**» I H- cr I I t I I I I I I I I I I I I I I I I I O UI »J W M !-• M M UI M M »* Kl •* •* © I- U> M M M H H •1 0» M SjWfJMWWNIOWMMMM oooo« Oo s rt U>MVOOC>KJOO>«J(»©»0»Wh-IS-JMH'.B»tn „ H M_ •. » h»_ _* . * •--jKjtfiCT'a'tj'-jff'H-A-^ff'KtOooo-gMuioooootoui-jo« F ( f 4 * o« > ff ooooeoooooeooooooooooooooooooo W fal 01 UI *WWU>U>U»U(«> WUUWW*UI* 4 a. OOOOt0t*OOOOOOOOOO©O<6U OOOOOh-000000000000000000000000 OOOOOOOOOOOOOOOoOOQOOOOOf O -J (» U> -J MMM O f O 0» 0> (SI OOOOOUlOOOUl^-OOOOOOOOOl-OOOOOOOOO tr M H" f- W Iti A «O M * O !-• ^dOttOUIt^UietUllAMUI UUUIUl^OiUIOlWfOOOOOOO 4»ookw«bvoi«« ^**»»«*»»»»1«»«^»»!«I!*»'«IH *tfiiuuoiaiuiuii>»ui9inui* * * UI M *J 10 M 0> O 9€ 37 Table Ilia. Radionuclide concentrations in ground-level air in Helsinki from March 12 to March 30, 1987 (/uBq/m3). Measurement error given in brackets. 7 131 134 137 Cs Sampling period I C* 12.3. 13.3. 3100 (1*) 62 (6%) 10 (26%) 19.5 (15%) 13.3. - 16.3. 4200 (5*) 15.3 (15%) 8.8 (21%) 24.7 (11%) 16.3. - 18.3. SOOO (4%) 11.7 (13%) 19.4 (6%) 44 (5%) IS.3. - 20.3. 4300 (3%) 5.» (10%) 21.9 (5%) 47 (4%) 20.3. - 24.3. 2500 (3*) 1.3 (30%) 14.2 (4%) 30 (4%) 24.3. - 30.3. 2930 (3*) 0* 7.4 (5%) 16.2 (5%) below th« detection limit Table nib. Radionuclide concentrations in ground-level air in Helsinki from August 10 to August 31, 1987 (^Bq/m3). Measurement error given in brackets. 131 134 137 Sampling period B« C» C» 10.8. - 11.8. 510 (8%) 0" 0 16.4 (22%) 11.8. - 12.8. 1430 (5%) 0 0 16.9 (18%) 12.8. - 14.8. 3400 (3%) 31 (4%) 12.2 (7%) 30 (5%) 14.8. - 18.8. 2860 (5%) 26.6 (6%) 13.0 (7%) 30 (6%) 18.8. - 21.8. 4300 (3%) 23.5 (5%) 8.1 (6%) 24.5 (4%) 21.8. - 24.8. 2740 (4%) 17.3 (5%) 0 47 (5*) 24.8. - 27.8. 2630 (4%) 6.4 (14%) 17.8 <5%> 49 (4%) 27.8. ~ 31.8. 2140 (4%) 0 11.7 (8%) 26.8 (5%) a below the detection limit 38 Table IV. Concentration of aerosol and gaseous form of l31l in air and penetration through the glass fibre filter in Nurmijärvi in 1987 (/xBq/m3). Measurement error given in brackets. Sampling period Clasa fibre Carbon bed Penetration filter (%) 2.3. - 16.3. 24.2" 112 {14%) 82 16.3. - 23.3. 4.6 13.0 <38%) 74 10.8. - 13.8. 14.4 (5*) 150 (19%) 91 13.8. - 17.8. 18.0 (4*) 270 (10%) 94 17.8. - 20.8. 35 (4*) 300 (11%) 90 20.8. - 24.8. 1.9 (11%) 64 (19%) 97 24.8. - 27.6. 5.9 (5%) 165 (11%) 97 mean value weighted with air volume Table V. Gamma-emitting radionuclides in the deposition at different stations in Finland in January 1987 (Bq/m2). Measurement error given in brackets. Results are decay-corrected to the median of the sampling period. For sampling stations see fig. 1. 95 106 110* 125 134. 137 144 Zr Ru Ag Sb Ca Cs Ce IVALO 0 0 0 0 1.7 (9%) 3.8 (7%) 0 JOENSUU 0 0 0 0 2.3 below the detection limit Table VI. Gamma-emitting radionuclides in the deposition at different stations in Finland in February 1987 (Bq/m2). Measurement error given in brackets. Results are decay-corrected to the median of the sampling period. For sampling stations see fig. 1. 95 106 110a «7_ 144 Zr Ru Ag U5S Ci b Ca Ce IVALO 0* 0 0 0 1.4 (8*) 3.0 (6%) 0 JOENSUU 0 0 0 0 2.6 (9*) 5.5 <7*> 0 JGXIOINEN 0 13 below the detection limit staple aisaing Table VII. Gamma-emitting radionuclides in the deposition at different stations in Finland in March 1987 (Bq/roJ). Measurement error given in brackets. Re sults are decay-corrected to the median of the sampling period. For sam pling stations see fig. 1. 95 106 110a 5 13«, Zr Ru *0 " sb C* Ca Ci IVALO 0* 0 0 0 3.1 (5%) 6.4 <5% ) 0 JOENSUU 0 0 0 0 1.5 (12%) 4.6 (7% ) 0 JOKIOINEN 2.7 U4%) 12 112%) 0 4.6 (10%) IS (3%) 36 (4 %) 24 (5%) JYVÄSKYLÄ 0 0 0 0 45 (3%) 100 (3% ) 6.7 (26%) KAJAANI 0 0 0 0 12 (4%) 29 (4 %) 2.5 (15%) KAUHAVA 0 0 0 0 19 (2%) 41 (2% ) 0 KUHMO 0 0 0 0 1.6 (15%) 5.1 (6 %) 5.3 (30%) KUOPIO 0 0 0 0 5.0 (7%) 10 (3 *) 0 LAPPEENRANTA 0 0 0 0 4.7 (9%) 10 (4 %> o HMUEHANN 0 0 1.4 (44%) 1.8 (44%) 11 (4%) 26 (3% > 0 NIINISALO 22 (10%) 93 (6%) 5.3 (12%) 12 (9%) 260 (1%) 590 (2% > 140 (4%) KUMI JÄRVI 0 4.9 «29%) 0 0 1.6 (8%) 6.7 (3% > 0 ROVANIEMI 0 0 0 0 0.49 (13%) 0.80 (7% > 0 SAVONLINNA 0 8.3 (23%) 0 1.1 (36%) 12 (4%) 27 (4% ) 0 SODANKYLÄ 0 0 0 0 22 (5%) 44 (5% ) 0 TAIVALKOSKI 0 0 0 0 0.75 (9%) 1.6 (6 %) 0 VAASA 0 0 0 0 21 (2%) 46 (2% ) 0 below the detection liait Table VIII. Gamma-emitting radionuclides in the deposition at different stations in Finland in April 1987 (Bq/ma). Measurement error given in brackets. Re sults are decay-corrected to the median of the sampling period. For sam pling stati MS see fig. 1. 95 106 110» 134 137 144 Zr Ru Ag "SSb Ca r • Cc1 a IVALO 0 0 0 0 3.1 <5%) 7.0 (5%) 0 JOENSUU 0 0 0 0 10 (4%) 23 (5%) 0 JOKIOINEN 0 4.5 (32*1 0 0 8.0 (5%) 17 (4%) 0 JYVÄSKYLÄ 0 22 (14%) 1.1 (32%) S.2 (14%) 110 (3%) 240 (3%) 10 (9%) KAJAANI 0 0 0 0 6.6 (3%) 16 (4%) 2.2 (21%) KAUHAVA 0 0 0 0 14 (3%) 32 (4%) 0 KUHMO 6.0 (22%) 25 (11%) 0 1.8 (20%) 17 (4%) 39 (4%) 140 (4%) KUOPIO 0 0 0 0 4.3 (4%) 9.8 (5%) 0 LAPPEENRANTA 0 8.1 (24%) 0 0 13 (3%) 28 (4%) 0 MARIEHANN 0 0 0 0 4.6 (6%) 11 (5%) 0 NIINISALO 0 0 0 3.7 (15%) 71 (4%) 160 (3%) 5,2 (13%) NURMIJÄRVI 0 0 0 0 5.3 (5%) 13 (5%) 0 ROVANIEMI 0 0 0 0 0.47 (9%) 0.6 8 (6%) 0 SAVONLINNA 0 0 0 0 12 (3%) 30 (3%) 0 SODANKYLÄ 0 0 0 0 2.9 (5%) 6 3 (5%) 0 TAIVALKOSKI 0 0 0 0 10 (3%) 25 (4%) 2.9 (24%) VAASA 0 0 0 0 16 (4%) 36 (5%) 0 a below the detection limit Table IX. Gamma-emitting radionuclides in the deposition at different stations in Finland in May 1987 (Bq/m2 ). Measurement error given in brackets. Results are decay-corrected to the median of the sampling period. For sampling stations see fig. 1. 95 106 lite 125 134. 137. 144. Zr Ru Kg Sb Cs Cs Ce IVALO 0 0 o 1.5 (7%) 4.2 JOENSUU 3.2 (35%) 0 0 o 2.0 (3%) 5.7 9 (29%) JOKIOINEN 0 0 0 o 14 (3%) 35 JYVÄSKYLÄ 0 0 0 o 60 (4%) 160 (12%> KAJAANI 0 0 0 o 7.6 (3%) 19 (14%) KAUHAVA 0 0 0 o 21 (2%) 49 KUHMO 0 0 0 o 2.7 (10%) 6.4 KUOPIO O 0 0 o 3.8 (5%) 8.5 CO LAPPEENRANTA 0 0 0 o 4.2 (6%) 11 MARIEKAHN 0 0 0 o 2.8 (7%> 8.1 NIINISALO 0 6.3 (33%) 0 o 39 (2%) 94 (14%) NURMIJÄRVI 0 0 0 o 4.5 (8%) 12 (19%) ROVANIEMI 0 0 0 o 0.47 (9%) 0.68 SAVONLINNA o 0 0 o 4.7 (6%) 12 SODANKYLÄ o 0 0 o 1.4 (11%) 2.8 TAIVALKOSKI o 0 0 o 0.86 (10%) 2.5 VAASA o 0 0 o 11 (3%) 25 below the detection liait Table X. Gamma-emitting radionuclides in the deposition at different stations in Finland in June 1987 (Bq/m2). Measurement error given in brackets. Re sults are decay-corrected to the median of the sampling period. Forsam- ling stations see fig. 1. 95 106 110» 125 134 137 144 Zr Ru Ag Sb Cl Ca Ca i IVALO 0 0 0 0 l.l (13%) 2.3 (10%) 0 JOENSUU 0 0 0 0 1.5 (13%) 3.3 (8%) 0 JOKIOINEN 0 12 (16*) 0 o.e7 (45%) 14 («%) 32 (4%) 4.9 (12%) JYVÄSKYLÄ 0 9.5 (23%) 0 3.0 (20%) 52 (4%) 120 (3%) 5.7 (14%) KAJAANI 0 0 0 0 6.3 (5%) 17 (4%) 4.8 (11%) KAUHAVA 0 0 0 0.9 (20%) 14 (2%) 34 (4%) 0 KUHMO 0 0 0 0 3.2 (9%) 8.0 (5%) 5.8 (12%) 0 ** KUOPIO 0 0 0 0 4.1 (4%) 11 (5%) *» LAPPEENRANTA 0 0 0 0 4.7 (6%) 12 (5%) 0 MARIEHAHN 0 0 0 1.0 (13%) 3.3 (4%) 7.2 (4%) 0 NIINISALO 0 1.2 (17%) 0 2.3 (15%) 35 (2%) 83 (4%) 3.9 (16%) NURMIJÄRVI 0 0 0 0 3.4 (5%) 9,4 (4%) 0 ROVANIEMI 0 0 0 0 0.47 (9%) 0.68 (6%) 0 SAVONLINNA 0 0 0 0 16 (3%) 39 (4%) 0 SODANKYLÄ 0 0 0 0 1.4 (6%) 2.8 (6%) 0 TAIVALKOSKI 0 0 0 0 1.2 (9%) 2.8 (6%) 0 VAASA 0 0 0 0 17 (3%) 41 (5%) 0 below the detection liftit Table XI. Gamma-emitting radionuclides in the deposition at different stations in Finland in July 1987 (Bq/m2). Measurement error given in brackets. Re sults are decay-corrected to the median of the sampling period. For sam pling stations see fig. 1. 95 106 110m 125_ 134 137 1*4. Zr Ru Ag Sb C» Ca Ca IVALO 0 0 0 0 1.2 (14%) 2.5 (9%) 0 JOENSUU 0 0 0 0 1.5 (9%) 3.5 <6%) 0 JOKIOINEN 0 0 0 0 11 <5%) 27 (4%) S. 3 (15%) JYVÄSKYLÄ 0 0 0 0 33 <4%> 83 (3%) 0 KAJAANI 0 7.1 (26%) 0 0 3.1 (6%) 7.7 (5%) 2.8 (23%) KAUHAVA 0 0 0 1 9 (22%) 13 (5%) 34 (5%) 0 KUHMO a 0 0 0 1.7 (11%) 3.7 (9%) 4.6 (16%) KUOPIO 0 0 0 0 2.4 (6%) 6.4 (6%) 0 tn LAPPEENRANTA 0 0 0 0 3.2 (5%) 6.8 (5%) 0 NARIEHAHN 0 0 0 0 1.7 (9%) 3.7 (7%) 0 NIINISALO 0 0 0 0 23 (4%) 61 (3%) 2.1 (19%) NURMIJÄRVI 0 0 0 0 4.9 (4%) 13 (4%) 0 ROVANIEMI 0 0 0 0 0.25 (19%) 0.71 (12%) 0 SAVONLINNA 0 4.4 (27*) 0 0 8.5 (5%) 21 (4%) 4.1 (16%) SODANKYLÄ 0 0 0 0 0.97 (12%) 3.1 (7%) 0 TAIVALKOSKI 0 0 0 0 1.1 (11%) 3.0 (7%) 0 VAASA 0 0 0 0 a.i (6%) 21 (5%) 0 below th« detection limit Table XII. Gamma-emitting radionuclides in the deposition at different stations in Finland in August 1987 (Bq/m2). Measurement error given in brackets. Re sults are decay-corrected to the median of the sampling period. For sam pling stations see fig. 1. 95 106_ 110» 125 134. 137. 144. Zr Ru Ag Sb Ca C» Ce IVALO 0 0 0 0 0.S9 (31*) 1.6 (18*) 0 JOENSUU 0 0 0 0 16 (3*) 42 (4*) 0 JOKIOINEN 0 9.4 «19%) 0 1.7 (24*) 11 (5*) 28 (4*) 3.0 (21*) JYVÄSKYLÄ 0 0 0 0 21 (3*) 57 (5%) 0 KAJAANI 0 S.5 (30%) 0 0 S.2 (5*) 17 (S*) 8.3 (11*) KAUHAVA 0 0 0 1.1 (29*) 18 (2*) 44 (4*1 0 KUHMO 0 s.s (30*) 0 0 2.0 <7*) S.2 (6*) 5.S (13*) KUOPIO 0 0 0 1.3 (30*) 10 (2*) 47 (4*) 4.7 (13*) ltk. LAPPEENRANTA 0 14 (21*1 0 0 14 (6t) 36 (5*) 0 WARIEHAHN 0 0 0 0 3.4 (6 k) 8.8 («*) 0 NIINISALO 0 4.2 (33*) 0 0 20 (4*) 53 (3*) 12 (7*) NURMIJÄRVI 0 0 0 0 6.9 (4*) 17 (4*) 0 ROVANIEMI 0 0 0 0 0.2S (19*) 0.71 (12*) 0 SAVONLINNA 0 0 0 0 4.6 (4*) 12 (4*) 0 SODANKYLÄ 0 0 0 0 1.0 (15*) 3.7 (7*) 0 TAIVALKOSKI 0 0 0 0 0.89 (14*) 2.2 (9%) 0 VAASA 0 0 0 0 26 (4*) 70 (3*) 0 a below the detection liaut Table XIII. Gamma-emitting radionuclides in the deposition at different stations in Finland in September 1987 (Bq/m2). Measurement error given in brackets. Results are decay-corrected to the median of the sampling period. For sampling stations see fig. 1. 95 106 125- 134. 137 "4 Zr Ru no*A g Sb C« Ca Ce IVALO 0 0 0 0 1.4 (9*) 3.4 (6*) 0 JOENSUU 0 0 0 0 0.64 (20%) 1.7 (12%) 0 JOKIOINEN 0 0 0 0 6.7 (4%) 20 (4%) 5.9 below the detection linit Table xiv. Gamma-emitting radionuclides in the deposition at different stations in in Finland in October 1987 (Bq/m2). Measurement error given in brackets. Results are decay-corrected to the median of the sampling period. For sampling stations see fig. 1. 95 106 110a, 125 134 13? 1*4. Zr Ru Ag Sb Cs Cs Ce IVALO 0 o o 1, 4 (12%) 3.6 (9%) 0 JOENSUU 0 o o o, 82 (14%) 1.9 (9%) 0 JOKIOINEN 0 o o 6. 2 <3%) 17 (4%) 4.7 (8%) JYVÄSKYLÄ 0 o o 15 (6%) 43 (5%) 0 KAJAANI 0 o o 3. 2 (5%) 9.1 (5%) 2.9 (14%) KAUHAVA 0 o o 7. 6 <6%) 20 (5%) 0 XUHHO 0 o o 1. 3 (12%) 2.6 (10%) 0 KUOPIO C (9%) 3.2 (7%) 0 o o 1.4 03 LAPPEENRANTA MARIEHAMN 0 o o 1.2 (12%) 3.2 (8%) 0 NIINISALO 0 o o 23 (3%) 58 (5%) 0 NURMIJÄRVI 0 o o 3.8 (4%) 11 (5%) 0 ROVANIEMI C o o 0.16 (15%) 0.3S (9%) 0 SAVONLINNA 0 o o 3,8 (6%) 11 (5%) 0 SODANKYLÄ 0 o o 0.68 (15%) 2.0 (8%) 0 TAIVALKOSKI 0 o o 0.92 (9%) 2.1 (7%) 0 VAASA 0 o o 5.8 (5%) IS (5%) 0 below the detection Halt ample missing Table XV. Gamma-emitting radionuclides in the deposition at different stations in Finland in November 1987 (Bq/m2). Measurement error given in brackets. Results are decay-corrected to the median of the sampling period. For sampling stations see fig. 1. 95 106 110a 125 134- 137 144 Zr Ru Afl Sb Cs Cs C« 1VAL0 0 0 0 0 1.7 <8%) 5.3 (5%) 2.4 (24%) JOENSUU 0 0 0 0 2.6 (11%) 5.7 (7%) 0 JOKIOINEN 0 0 0 0 6.1 (4%) 18 (5%) 2.5 (27%) JYVÄSKYLÄ 0 0 0 0 19 (3%) 50 (5%) 0 KAJAANI 0 0 0 0 0.92 (12%) 2.9 (7%) 0 KAUHAVA 0 0 0 0 7.6 (4%) 22 (5%) 0 KUHNO 0 0 0 0 0.98 (13%) 2.8 (8%) 0 KUOPIO 0 0 0 0 4.1 (5%) 10 (5%) 0 ltk LAPPEENRANTA 0 0 0 0 l.« (10%) 4.7 (5%) 0 NARIEKAHN 0 0 0 0 1.4 (9%) 4.2 (6%) 0 NIINISALO 0 0 0.7» (27%) 0 16 (3%) 47 (5%) 1.9 (27%) NURMIJÄRVI 0 32 (9%) 0 3.6 (12%) 9.5 (5%) 28 (4%) 0 ROVANIEMI 0 0 0 0 0.16 (15%) 0.35 (9%) 0 SAVONLINNA 0 0 0 1.3 (28%) 6.9 (5%) 18 (4%) 0 SODANKYLÄ 0 0 0 0 0.69 (11%) 2.2 (7%) 0 TAIVALKOSKI 0 0 0 0 1.1 (8%) 2.9 (6%) 0 VAASA 0 0 0 0 6.2 (5%) 19 (5%) 20 (6%) a below the detection liitit Table XVI. Gamma-emitting radionuclides in the deposition at different stations in Finland in December 1987 (Bq/m2). Measurement error given in brackets. Results are decay-corrected to the median of the sampling period. For sampling stations see fig. 1. 95 106 110a 125 134 137^ 144. Zr J»u Ag Sb Cm C» Ce IVALO 0 0 0 0 1.1 (10%) 2.2 (7%) 0 JOENSUU 0 0 0 0 0.32 (29%) 1.3 (11%) 0 JOKIOINEN 0 6.1 (25*) 0 0 3.3 (6%) 9.7 (5%) 4 0 (18%) JYVÄSKYLÄ 0 0 0 1.3 (33*) 25 (2%) 69 (3%) 0 KAJAANI 0 3.3 (26») 0 0 3.8 (6%) 11 (4%) 13 (5%) KAUHAVA 0 0 0 2.6 (19*) ->8 (2%) 110 (4%) 0 KUHMO 0 0 0 0 2.5 (4%) 7.0 (4%) 1 0 (31%) KUOPIO 0 0 0 0 1.7 (8%) 4.7 (5%) 0 Ui O LAPPEENRANTA 0 0 0 0 1.9 (9%) S.4 (7%) 0 NARIEMANN 0 0 0 0 1.9 te%> 5.2 (6%) 0 NIINISALO 0 0 0 0 16 (5%) 45 (5%) 0 NURMIJÄRVI 0 0 0 0 2.6 (7%) 7.8 (6%) 0 ROVANIEMI 0 0 0 0 0,16 (15%) 0.35 (9%> 0 SAVONLINNA 0 0 0 0 1.9 (9%) 4.9 (7%) 5 6 (12%) SODANKYLÄ 0 0 0 0 0.97 (16%) 2.5 (8%) 0 TAIVALKOSKI 0 0 0 0 0.67 (11%) 1.9 (7%) 0 VAASA 0 0 0 1.0 (24%) 11 (4%) 32 (4%) 0 below the detection liait 134 ~ HDA Cs 51 Table XVII. ,0Sr in the deposition at different stations in Finland in 1986 (results which were not included in the earlier report14 ) (Bq/m2/3 months) and total amounts of 90Sr at each station in 1986 (Bq/m2/year). Jul-Sep Oct-Dec Total 1986 Ivalo 0.30" 0.62 7 Joensuu 18 0.82 29 Jokioinen 30 15 130 Jyväskylä 60 24 280 Kaj aani 19 4.1 230 Kauhava 36 4.7 250 Kuhmo 12 4.4 590 Kuopio 8.5 1.1 180 Lappeenranta 2.3 2.9 44 Mariehamn 4.3 1.7 120 Niinisalo 45 21 420 Nurmijärvi 3.7 5.1 110 Savonlinna 9.5 1.5 47 Sodankylä 0.51" 0.48 11 Taivalkoski 0.89 0.49 4 Vaasa 7.4" 4.8 140 • July missing Table XVIII. *> Sr in the deposition at different stations in Finland in 1987 (Bq/m2/3 months or Bq/m2/6 months and Bq/m2/ year). Jan-Mar Apr-Jun Jul-Sep Oct-Dec Jan-Jun Jul-Dec Total Ivalo 0.58 0.86 1.4 Joensuu 0.44 0.84 0.58 1.9 Jokioinen 17 2.1 3.2 4.9 27 Jyväskylä 8.9 9.2 1.9 3.0 23 Kaj aani 20 4.2 24 Kauhava 13 1.8 6.1 1.6 23 UI Kuhmo 4.3 30 1.7 1.5 38 Kuopio 1.9 0.64 2.3 4.8 Lappeenranta 1.5 1.0 1.1 3.6 Mariehamn 1.5 0.67 2.2 Niinisalo 22 4.1 3.6 2.1 32 Nurmijärvi 0.90 1.7 0,74 1.3 4.6 Savonlinna 3.6 1.7 4.7 10 Sodankylä 1.8 0,80 2.6 Taivalkoski 0.94 0.63 1.6 Vaasa 7.6 8.9 17 53 Table XIX. Depositions of transuranic elements collected in Nurmijärvi and Lappeenranta (mBq/m2 in sampling period) Sampling periods varied from one to six months. 2<1 242 2 3Spu 2 3 9. 2 40pu Am Cro 243.244Cm Nurmijärvi 1986 Jun* 3.0 7.8 3.5 79 0.95 Jul 0.72 0.77 1.4 28 0b Aug 1.8 4.2 0.62 50 0.99 Sep 0.19 1.0 0.59 3.5 0.23 Oct 1.7 2.5 0.79 21 0.23 Nov 0.14 0.65 0.10 0.81 0 Dec 0.72 1.4 0.94 4.8 0.99 1987 Jan-Feb 0.58 1.2 0.88 5.3 0.59 Mar 0.21 0.57 0.73 2.2 0.27 Apr 0 0.58 0.46 0 0 May 0.49 0.83 0.20 0 0 Jun-Jul 0.80 1.6 1.4 3.6 0 Aug-Sep 0 1.4 0 0 0 Oct 1.0 4.5 4.9 0 0 Nov-Dec 0 0.95 0 0 0 Lappeenranta 1987 Jan-Jun 3.0 10 1.8 0 0 Jul-Dec 0.43 3.9 -c - ™ • from 31.5..8 6 b below the detection limit c not analysed Table XX. Monthly activity concentrations of 3H in rain water (kBq/m3) and total annual depositions (kBq/m2) at four Finnish sampling stations in 1986 and 1987. Total Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec annual depos. Inari, Nellimö 1986 2.3 1.9 1,6 _» 2.3b 3.7 4.3 3.6 3.7 1.9 2.8 1,9 1.4 1987 2.0 2.7 2.4 1.7 4.0 3.5 3.6 3.7 4.2 3.0 2.0 2.0 1.7 Kuhmo 1986 2.6 2.6 3.1 - 4.3 5.0 4.4 4.4 2.8 2.1 2.0 1.6 2.2 1987 1.0 2.1 2.9 3.0 4.1 2.9 3.0 4.4 3.6 3.6 2.1 2.8 2.0 Nurmijärvi 1986 3.8 - 1.7 - 2.6 - 4.0 2.8 2.9 2.0 2.6 2.1 1.9 1987 2.1 2.2 2.1 - 2.6 3.4 4.5 4.2 2.7 3.1 3.6 2.2 1.8 Rovaniemi, Apukka 1986 3.1 3.1 2.0 2.6 3.1 4.4 5.1 3.5 3,3 3.4 2.6 4.3 1.7 1987 2.6 2.2 2.1 1.6 2.7 2.3 3.1 2.9 3.4 3.0 2.0 2.2 1.3 * not analysed b samples of April and May analysed together 55 Table XXI. Ratio of 137 Cs originating from Chernobyl de posited in 1987 to that in 1986 (%) at different stations in Finland. Amounts corrected with old global fallout. Stations with total deposition >3000 fiq/m2 in 1986: Nurmijärvi 2.2 Jokioinen 4.8 Niinisalo 3.4 Lappeenranta 3.9 Jyväskylä 5.7 Vaasa 4.1 Kauhava 4.2 Kuopio 4.6 Kuhmo 1.1 Kajaani 3.0 x = 3.9 + 1.3 Stations with total deposition 500-3000 Bq/m2 in 1986: Mariehamn 10 Savonlinna 12 Joensuu 18 x = 13 + 4 Stations with total deposition 140-310 Bq/m2 in 1986: Taivalkoski 39 Sodankylä 35 Ivalo 20 x = 31 + 10 56 Table XXII. Ratio of 90Sr deposited in 1987 to the 1986 figure (%) at different stations in Finland. % Nurmij ärvi 4.2 Mariehamn 1.9 Niinisalo 7.7 Lappeenranta 8.2 Jyväskylä 8.2 Joensuu 6.6 Vaasa 11 Kauhava 9.1 Kuopio 2.7 Kuhmo 6.4 Kajaani 10 x = 6.9 + 2.9 Jokioinen 21 Savonlinna 21 Taivalkoski 34 Sodankylä 24 Ivalo 18 x = 24 + 6 57 Table XXIII. Accumulated deposition of 90Sr and 137Cs at different sampling stations in Finland from the nuclear weapon test period to the end of 1987 (Bq/m2 ). 90Sr 137 Cs Ivalo 1100 1900 Joensuu 1100 2400 Jokioinen 1200 10000 Jyväskylä 1300 22000 Kajaani 1300 6800 Kauhava 1300 31000 Kuhmo 1700 9900 Kuopio 1200 5300 Lappeenranta 1100 5100 Mariehamn 1200 2800 Nurmij ärvi 1200 9400 Niinisalo 1500 35000 Rovaniemi 2900 Savonlinna 1100 4700 Sodankylä 1100 2200 Taivalkoski 1100 1900 Vaasa 1200 13000 58 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY P.O.Box 268, SF-00101 HELSINKI, FINLAND Institute of Radiation Physics (SFL) 1958 - 1975 Institute of Radiation Protection (STL) 1975 - 1984 Finnish Centre for Radiation and Nuclear Safety (STUK) since 1st March 1984 Report code prefix letters (representing the acronym of the Finnish name of the institution) have been changed with the names of the institution. Report numbers continue in the original progressive series. SFL-A reports: SFL-A2 Castren O. Gammaspectrometric determinations of caesium-137 and potassium in Finnish milk. Helsinki, 1966. SFL-A3 Paakkola O. Radiostrontium in milk, grass and some other biological samples in Finland. Helsinki, 1966. SFL-A4 Salo A. Strontium-90 and caesium-137 in wacer in Finland. Helsinki, 1966. SFL-A5 Castren O. An Algol programme for the detection efficiences around a cylindrical scintillation cristal. Helsinki, 1966. SFL-A6 Suomela M. The construction and calibration of the whole-body counter in the Institute of Radiation Physics. Helsinki, 1967. SFL-A7 Toivonen M. On routine personnel dosimetry with fluoroglasses. Helsinki, 1967. SFL-A8 Studies on environmental radioactivity in Finland. Annual Report. Helsinki, 1967. SFL-A9 Bagge P, Salo A. Biological detectors of radioacti ve contamination in the Baltic. Helsinki, 1967. SFL-A10 Isola A. A portable survey meter for low-level radia tion measurements. Helsinki, 1967. SFL-A11 Toivonen M, Isola A. On the exposure of radiological employees in Finland during 1965-1967. Helsinki, 1968. SFL-A12 Studies on environmental radioactivity in Finland 1967. Annual Report. Helsinki, 1968. SFL-A13 Toivonen M. An arrangement for read-out of luminescent dosimeters. Helsinki, 1969. SFL-A14 Kahlos H. Radon-222 concentration of some water samples determine with gammaspectrometric measurements. Helsinki, 1969. 59 SFL-A15 Asikainen M, Blomqvist L. Measurements of airborne radionuclide in Finland with a highvolume air sampler and Ge(Li)-spectroscopy. Helsinki, 1970. SFL-A16 Kahlos H, Suomela M. Studies on the elimination rate and the radiation exposure following ingestion of radon-222 rich water. Helsinki, 1970. SFL-A17 Studies on environmental radioactivity in Finland 1968-1970. Annual Report. Helsinki, 1971. SFL-A18 Rannikko S, Uotila I, Kiviniitty K. Measurements of radiation output of telecobalt units in Finland. Hel sinki, 1971. SFL-A19 Kahlos H, Asikainen M. Natural radioactivity of ground water in the Helsinki area. Helsinki, 1973. SFL-A20 Salo A, Saxen R. On the role of humic substances in the transport of radionuclides. Helsinki, 1974. STL-A reports: STL-A21 Studies on environmental radioactivity in Finland 1971-1975. Annual Report. Helsinki, 1977. STL-A22 Bjarland B. The Hytype printer as versatile output device in small NOVA configurations. Helsinki, 1976. STL-A23 Uotila I. CAMAC extension for BASIC on the NOVA 1200 minicomputer. Helsinki, 1976. STL-A24 Asikainen M, Kahlos H. Natural radioactivity of ground and surface water in Finland = Pohja- ja pinta vesien luonnollinen radioaktiivisuus Suomessa. Helsin ki, 1977. STL-A25 Rannikko SJ, Sinitsin RV (ed.). Clinical dosimetry: proceedings of the Soviet-Finnish Cooperative Meeting on Clinical Dosimetry, Leningrad, USSR, 6-10 December 1976. Helsinki, 1979. STL-A26 Studies on environmental radioactivity in Finland 1976-1977. Annual Report. Helsinki, 1979. STL-A27 Toivonen M. Individual TL detector characteristics in automated processing of personnel dosemeters: correction factors as extension to identify codes of dosemeter cards. Helsinki, 1979. STL-A28 Bjarland B. Microcomputer control of automated TL reader. Helsinki, 1979. STL-A29 Stenstrand K, Toivonen H, Rytömaa T. Radiation- induced chromosome aberrations in human lymphocytes: dose-response relationships after irradiation in vitro with 200 kV X-rays and 60-Co gamma rays. Helsinki, 1979. 60 STL-A30 Toivonen H. A flexible multipurpose model for normal and transient cell kinetics. Helsinki, 1980. STL-A31 Toivonen H. Transient cell kinetics. Applications of tracer techniques to cancer research and radiobiology. Helsinki, 1980. STL-A32 Studies on environmental radioactivity in Finland 1978. Helsinki, 1980. STL-A33 Rantanen E. Calibration of neutron rem counters: discussion on different results obtained in two labora tories. Helsinki, 1980. STL-A34 Studies on environmental radioactivity in Finland 1979. Helsinki, 1981. STL-A35 Rannikko S. Concept of the population mean malignancy dose. Helsinki, 1981. STL-A36 Rannikko S, Heinämaa R. Number of medical X-ray examinations, their distribution and doses to bone marrow in 1978. Helsinki, 1981. STL-A37 Rannikko S. Problems concerning the assessment of the radiation dose to population as a result of X-ray examinations. Helsinki, 1981. STL-A38 Studies on environmental radioactivity in Finland 1980. Helsinki, 1981. STL-A39 Asikainen M. Natural radioactivity of ground water and drinking water in Finland. Helsinki, 1982. STL-A40 Studies on environmental radioactivity in Finland 1981. Helsinki, 1983. STL-A41 Rajama J, Rantavaara A. Radioactivity in Finnish cereals from 1962 to 1980. Helsinki, 1982. STL-A42 Turai I, Toivonen H. Radiohygiene of fission isotopes of iodine: experiments in rats and model studies in man. Helsinki, 1983. STL-A43 Servomaa A, Toivonen M, Kiuru A. Mailed TL dosimeters for monitoring the output from diagnostic x-ray equip ment. Helsinki, 1983. STL-A44 Servomaa A. Significance of x-ray diagnostic quality assurance in terms of radiation impact to patients, Helsinki, 1983. STL-A45 Suomela M. Whole-body counter studies in radiation protection and clinical research, Helsinki, 1983. STL-A46 Arvela H. A Nordic intercomparison and evaluation of the detractor responds to natural environmental gamma radiation. Helsinki, 1983. 61 STL-A47 Studies on environmental radioactivity in Finland 1982. Helsinki, 1984. STL-A48 Studies on environmental radioactivity in Finland 1983. Helsinki, 1984. STUK-A reports: STUK-A49 Tarvainen M, Riihonen M. Spent fuel measurements at Loviisa nuclear power station. May, 1982. Helsinki, 1984. STUK-A50 Järvinen H, Rannikko S, Servomaa A. Report on the Nordic-Soviet meeting on standard and applied dosim etry, Helsinki, 9-11 November 1983. Helsinki, 1984. STUK-A51 Arvela H, Winqvist K. Influence of source type and air exchange on variations of indoor radon concentra tion. Helsinki, 1986. STUK-A52 af Ekenstam G, Tarvainen M. Independent burnup verifi cation of BWR-type nuclear fuel by means of the 137Cs activity. Helsinki, 1987. STUK-A53 Järvinen H, Rantanen E, Jokela K. Testing of radiothe rapy dosimeters in accordance with IEC specification. Helsinki, 1986. STUK-A54 Studies on environmental radioactivity in Finland 1984-1985. Annual Report. Helsinki, 1987. STUK-A55 Studies on environmental radioactivity in Finland in 1986. Annual Report. Helsinki, 1987. STUK-A56 Sinkko K, Aaltonen H, Taipale TK, Juutilainen J. Airborne radioactivity in Finland after the Chernobyl accident in 1986. Supplement 1 to Annual Report STUK-A55. Helsinki, 1987. STUK-A57 Saxen R, Taipale TK, Aaltonen H. Radioactivity of wet and dry deposition and soil in Finland after the Chernobyl accident in 1986. Supplement 2 to Annual Report STUK-A55. Helsinki, 1987. STUK-A58 Rantavaara A, Haukka S. Radioactivity of milk, meat, cereal.j and other agricultural products in Finland after the Chernobyl accident in 1986. Supplement 3 to Annual Report STUK-A55. Helsinki, 1987. STUK-A59 Rantavaara A. Radioactivity of vegetables and mush rooms in Finland after the Chernobyl accident in 1986. Supplement 4 to Annual Report STUK-A55. Helsin ki, 1987. STUK-A60 Saxen R, Aaltonen H. Radioactivity of surface water in Finland after the Chernobyl accident in 1986. Supplement 5 to Annual Report STUK-A55. Helsinki, 1987. 62 STUK-A61 Saxen R, Rantavaara A. Radioactivity of fresh water fish in Finland after the Chernobyl accident in 1986. Supplement 6 to Annual Report STUK-A55. Helsinki, 1987. STUK-A62 Rantavaara A, Nygren T, Nygren K, Hyvönen T. Radioac tivity of game meat in Finland after the Chernobyl accident in 1986. Supplement 7 to Annual Report STUK-A55. Helsinki, 1987. STUK-A63 Rissanen K, Rahola T, Hiukka E, Alfthan A. Radioacti vity of reindeer, game and fish in Finnish Lapland after the Chernobyl accident in 1936. Supplement 8 to Annual Report STUK-A55. Helsinki, 1987. STUK-A64 Rahola T, Suomela M, Hiukka E, Puhakainen M, Pusa S. Radioactivity of people in Finland after the Chernobyl accident in 1986. Supplement 9 to Annual Report STUK- A55. Helsinki, 1987. STUK-A65 Arvela H, Blomqvist L, Lemmelä H, Savolainen A-L, Sarkkula S. Environmental gamma radiation measurements in Finland and the influence of the meteorological con ditions after the Chernobyl accident in 1986. Supple ment 10 to Annual Report STUK-A55. Helsinki, 1987. STUK-A66 Hus E, Sjöblom K-L, Saxen R, Aaltonen H, Taipale TK. Finnish studies on radioactivity in the Baltic Sea after the Chernobyl accident in 1986. Supplement 11 to Annual Report STUK-A55. Helsinki, 1987. STUK-A67 Hus E, Sjöblom K-L, Aaltonen H, Klemola S, Arvela H. Monitoring of radioactivity in the environs of Finnish nuclear power stations in 1986. Supplement 12 to Annual Report STUK-A55. Helsinki, 1987. STUK-A68 Puhakainen M, Rahola T, Suomela M. Radioactivity of sludge after the Chernobyl accident in 1986. Supplement 13 to Annual Report STUK-A55. Helsinki, 1987. STUK-A69 Salmenhaara S, Tarvainen M. Nondestructive measure ments with a WWER-440 fuel assembly model using neutron and gamma sources. Helsinki, 1987. STUK-A70 Hellmuth K-H. Rapid determination of strontium-89 and strontium-90 - experiences and results with various methods after the Chernobyl accident in 1986. Helsinki, 1987. STUK-A71 Keskitalo J. Effects of thermal discharges on the benthic vegetation and phytoplankton outside the Olki luoto nuclear power station, west coast of Finland. Helsinki, 1988. STUK-A72 Keskitalo J. Effects of thermal discharges on the benthic vegetation and phytoplankton outside the Olki luoto nuclear power station, west coast of Finland: summary. Helsinki, 1988. 63 STUK-A73 Järvinen H, Bregazde JI, Berlyand VA, Toivonen M. Com parison of The National Standards for the measure ments of absorbed dose at 6 ° Co gamma radiation. Helsin ki, 1989. STUK-A74 Studies on environmentr" radioactivity in Finland in 1987. Annual Report. Helsinki, 1989. (to be published in 1990) STUK-A75 Saxen R, Aaltonen H, Ikäheimonen TK. Airborne and depo sited radioactivity in Finland in 1987. Supplement 1 to Annual Report STUK-A74. Helsinki, 1989. STUK-A76 Arvela H, Markkanen M, Lemmela H, Blomqvist L. Environ mental gamma radiation measurements in Finland in 1986-87. Supplement 2 to Annual Report STUK-A74. Helsinki, 1989. STUK-A77 Saxen R, Rantavaara A. Radioactivity of surface water and fresh water fish in Finland in 1987. Supplement 3 to Annual Report STUK-A74. Helsinki, 1989. (to be pub lished in 1990) STUK-A78 Rantavaara A. Radioactive substances of foodstuffs in Finland in 1987. Supplement 4 to Annual Report STUK-A74. Helsinki, 1989. (to be published in 1990) STUK-A79 Sjöblom K-L, Klemola S, Hus E, Arvela H, Blomqvist L. Monitoring of radioactivity in the environs of finnish nuclear power stations in 1987. Supplement 5 to Annual Report STUK-A74. Helsinki, 1989. STUK-A80 Rissanen K, Rahola T, Hiukka E, Alftan A. Radioactivity in reindeer, game, fish and plants in finnish Lappland in 1987. Supplement 6 to Annual Report STUK-A74. Helsin ki, 1989. (to be published in 1990) STUK-A81 Rahola T, Suomela M, Hiukka E, Pusa S. Radioactivity of people in Finland in 1987. Supplement 7 to Annual Report STUK-A74. Helsinki, 1989. STUK-A82 Ikäheimonen TK, Hus E, Saxen R. Finnish Studies in radio activity in the Baltic Sea in 1987. Supplement 8 to Annual Report STUK A-74. Helsinki, 1988. STUK-A83 Hus E, Klemola S, Sjöblom K-L, Ikäheimonen TK. Radioac tivity of Focus veslculosus along the finnish coast in 1987. Supplement 9 to Annual Report STUK-A74. Helsinki, 1988. STUK-A84 Puhakainen M, Rahola T. Radioactivity of sludge in Finland in 1987. Supplement 10 to Annual Report STUK-A74. Helsin ki, 1989. ISBN 951-47-14660 ISSN 0781-1705