Monitoring of r adioactive contaminations of bottom sediments and - PowerPoint PPT Presentation

Monitoring of r adioactive contaminations of bottom sediments and fish in the southern Baltic Sea, 2016 Maria Suplińska a , Barbara Rubel a , Tamara Zalewska b a Central Laboratory for Radiological Protection, Warszawa b Institute of Meteorology and Water Management , Maritime Branch- Gdynia Performed under an agreement of National Atomic Energy Agency, Warsaw HELCOM-MORS 7, Tallinn 2017

Research includes determination of radioactive contaminations in the southern Baltic Sea marine environment elements: bottom sediments and biota (fish). Samples were collected ones a year: in February -fish samples (commercial catches) in June – sediment core samples (collected during the cruise onboard r/v Baltica at 6 sampling locations Methods  137 Cs - gamma spectrometry;  239,240 Pu, 238 Pu - radiochemical method with 242 Pu as a tracer, and alpha spectrometry.  90 Sr - radiochemical method and the measurement of 90 Y activity concentration after establishing the radioactive equilibration of 90 Sr - 90 Y.  226 Ra - determined by emanation method (measurement of 222 Rn in Lucas-type scintillation chambers) preceded by separation of radium. HELCOM-MORS 7, Tallinn 2017

Bottom sediments Baltic Sea P140 P5 P1 P39 P116 P110 Fig 1. Sampling stations of bottom sediments From each location, six core samples were taken and divided into 12 depth layers: 1cm layers ( to the depth of 5 cm), and 2 cm layers (from 5cm to 19cm depth). In addition, at each station one core sample (0-19 cm) was collected. HELCOM-MORS 7, Tallinn 2017

Activity concentrations of 137 Cs in bottom sediments Table 1. The average activity concentrations of 137 Cs 137 Cs, Bq kg -1 sdw. in the layers from 0 to 5 cm 0 50 100 150 200 250 0 Sampling 137 Cs, 2 P 110 [Bq kg -1 location dw ] 4 P 116 6 172 ± 12* P 110 P 1 8 (156 – 187) Depth, cm P 140 10 166 ± 24 P 5 P 116 12 (135 – 192) P 39 14 155 ± 20 16 P 1 (123 – 177) 18 102 ± 15 20 P 140 (82 – 124 ) Fig. 2. Vertical distribution of 137 Cs in bottom sediments in 2016 41.0 ± 6.3 P 5 (30 – 48) In 2016 concentrations of 137 Cs in bottom sediments were slightly 47.4 ± 3.7 lower than in 2015. P 39 The highest concentrations of 137 Cs, observed in the Gdansk Basin (43 – 51) (P110, P116, P 1), ranged from 177 Bq kg -1 dw to 192 Bq kg -1 * SD dw while in Bornholm Basin (P 5, P 39) the concentrations in the upper layers were in the range 48.1 ÷ 50.8 Bq kg -1 dw . HELCOM-MORS 7, Tallinn 2017

Vertical distribution of 239,240 Pu and 238 Pu in bottom sediments Determination of plutonium in bottom sediments from 6 locations are carried out every three years In 2016, plutonium was analysed in two locations:P116 (Gulf 239,240 Pu, Bq kg -1 of Gdansk) and P39 (Bornholm Basin) dw 0 2 4 6 8 10 0 At P116 concentrations of 239,240 Pu increased from 2 P110/2014 1.41 Bq kg -1 dw (0-1cm) to 3.62 Bq kg -1 dw (3-4cm), 4 P140/2015 then were aligned in the layers from 4 cm to 13 cm with the 6 P5/2015 average value of 3.28 ± 0.31 Bq kg -1 Depth, cm P1/2015 8 dw the decrease to 0.50 Bq kg -1 dw was observed in the lowest layer P116/2016 10 P39/2016 12 At P39 239,240 Pu concentrations were about three times lower. 14 After a slight increase from 1.08 Bq kg -1 dw to 1.36 Bq kg -1 dw , 16 concentrations of 239,240 Pu were aligned in layers 2 – 9 cm with the 18 average value equal to 1.30 ± 0.10 Bq kg -1 dw . 20 Below 15cm 239,240 Pu concentration do not exceed 0.05 Bq kg -1 dw . Fig.3. Vertical distribution of 239,240 Pu concentrations in years 2014-2016 The activity concentrations of 238 Pu in P 116 were in range 0.013 ÷ 0.099 Bq kg -1 dw and in P 39 ranged from < 0.002 Bq kg -1 dw to 0.042 Bq kg -1 dw . The rate of 238 Pu to 239,240 Pu in both locations was in range 0.02 ÷ 0.04 being similar to that determined for the fallout from nuclear weapons tests. HELCOM-MORS 7, Tallinn 2017

Strontium-90 Table 2. Activity concentration of 90 Sr, in the layer 0-19 cm of bottom sediments and activity concentration of 137 Cs and 239,240 Pu recalculated for this layer 90 Sr 137 Cs 239,240 Pu Sampling [Bq kg -1 [Bq kg -1 [Bq kg -1 location dw ] dw ] dw ] P 110 2.34 ± 0.11 79.0 ± 1.4 3.11 ± 0.12 Activity concentrations of 90 Sr in bottom P 116 3.19 ± 0.21 73.5 ± 1.3 2.74± 0.13 sediments were performed in integrated P 1 3.02 ± 0.22 103 ± 2.0 1.83 ± 0.08 samples taken from the layer 0-19 cm. 90 Sr concentrations were in the range P 140 2.56 ± 0.16 58.9 ± 2.5 0.93 ± 0.07 2.26 ÷ 3.19 Bq kg -1 dw , being even 30 times lower than 137 Cs concentrations P 5 2.26 ± 0.16 23.1 ± 2.1 0.47 ± 0.02 (recalculated for the same layer). Concentrations of 239,240 Pu were in the P 39 2.89 ± 0.19 21.7 ± 1.3 1.25± 0.11 similar range to 90 Sr. HELCOM-MORS 7, Tallinn 2017

Spatial distribution of antropogenic isotopes in bottom sediments 6 Cs-137, 2016 240 5 Sr-90, 2016 137 Cs, kBqm -2 180 4 3 90 Sr, Bq m -2 120 2 60 1 0 0 P 110 P 116 P 1 P 140 P 5 P 39 P110 P116 P1 P140 P5 P39 240 8 2014-2016 Pu-239,240 The total amount of 137 Cs in 2016 ranged Pu-238 180 6 sm from 1.02 kBq m -2 in the Bornholm Deep (P5) sm 238 Pu, Bq kg -1 239,240 Pu, Bq kg -1 to 4.77 kBq m -2 in the Gulf of Gdansk (P110). 120 4 The range of total amount of 90 Sr was 88 ÷ 134 Bq m -2 60 2 and total amounts of 239,240 Pu and 238 Pu were in ranges: 28.8 ÷ 199 Bq m -2 and 0.76 ÷ 5.98 Bq m -2 , respectively 0 0 P110 P116 P1 P140 P5 P39 Fig. 4 Total amounts of 137 Cs, 90 Sr, 239,240 Pu and 238 Pu in bottom sediments, layer of 0-19 cm HELCOM-MORS 7, Tallinn 2017

Activity concentrations of selected radionuclides in four fish species Table 3. The average concentrations of 137 Cs, 40 K and 226 Ra in Baltic Sea fish flesh, 2016 Species/ 137 Cs 40 K 226 Ra Weight of Number of total number samples [Bq kg -1 [Bq kg -1 [Bq kg -1 sample [g] w.w ] w.w ] w.w ] of pieces 4.52 ± 0.51 a) 111 ± 17 0.095 ± 0.003 Cod 5 500-670 30 4.06 – 5.26 b) 83 – 126 0.092 – 0.100 2.55 ± 0.74 110 ± 19 0.028 ± 0.003 Herring 5 500-550 109 1.68 – 3.33 86 – 133 0.023 – 0.031 Sprat c) 2.79 ± 0.19 105 ± 9 0.068 ± 0.005 5 520-620 279 2.53 – 2.98 92 – 114 0.062 – 0.076 3.32 ± 0.52 97 ± 6 0.055 ± 0.003 Plaice 5 500-505 33 3.15 – 4.22 86 – 104 0.052 – 0.059 a) standard deviation b) range of concentrations c) whole fish without a head The highest average activity concentration of 137 Cs was found in cod – 4.52 Bq kg -1 ww and the lowest in herring – 2.55 Bq kg -1 ww. Activity concentrations of 226 Ra ranged from 28 mBq kg -1 ww in herring to 95 mBq kg -1 ww in cod. HELCOM-MORS 7, Tallinn 2017

16 14 12 fw. 10 137 Cs, Bq kg -1 8 6 4 2 0 Fig 5. Average activity concentrations of 137 Cs in Baltic Sea fish flesh in the years 1985-2016 The average 137 Cs concentration calculated for the four species in 2016 was equal to 3.29 ± 0.88 Bq kg -1 ww . Activity concentration of 137 Cs in the Baltic Sea fish has decreased in years, but it is still higher than before the Chernobyl accident. HELCOM-MORS 7, Tallinn 2017

Summary  The highest concentrations of 137 Cs occurred in the upper sediment layers and decreased along the profiles. As in previous years, differences in the concentrations of 137 Cs related to the location were observed.  The highest concentrations of 239,240 Pu and 238 Pu occurred in deeper sediment layers, and the ratio of 238 Pu to 239,240 Pu in the individual layers are in range 0.02- 0.04, being typical of the radioactive fallout after the nuclear weapons test.  In the southern Baltic Sea no significant differences in the spatial distribution of 90 Sr in the bottom sediments were observed.  Contamination in fish due to 137 Cs was reduced about 4 times comparing with maximum observed in 1989, but is still higher than before the Chernobyl accident. The activity concentration of 137 Cs and 226 Ra in fish depends on their species, mainly due to the kind of nutrition . HELCOM-MORS 7, Tallinn 2017

Thank you for your attention HELCOM-MORS 7, Tallinn 2017