in agricultural areas

Transkript

1 Klas Rosén Department of Soil and Environment Radioecology and countermeasures after radioactive fallout in agricultural areas SLU - Uppsala Klas.Rosen@mv.slu.se NKS, Oslo April 2010

2 The radioecology group at SLU in Sweden Research group for terrestrial radioecology; people Preparedness team for the case of events with for nuclear accidents; - additional 3 people

3 Radioecology activities at SLU rests on four legs 1. Research: Agricultural ecosystem, Forest ecosystem and basic radiation protection 2. Environmental monitoring and assessment (FOMA): Quality assurance of 3 different databases, National Preparedness in radiation protection: Emergency laboratory 4. Education: Courses for Research in REK at SLU, for government and industry. Supervising graduate students, visiting scientists and degree students (MSc and BSc)

4 Risk assessment after radionuclide fallout Uppsala county 1 week after

5 A radioactive fallout affects the whole society and the individual people This effects the population to great extend - Intake of iodine tablets, - food restrictions - indoor stay - evacuation - countermeasures in agriculture Decisions must be taken in a short time

6 Action Strategies Decisions have to be taken in short - or later time Cost of a dimmension Kostnad i en dimension Decision later Beslut senare Cost for one person Kostnad för en part Nytta för en annan Benefit of another person Beslut nu Decision now Kostnad i en annan The cost of another dimmension

7 Basic international recommendations for action after nuclear fallout ICRP's general recommendations, says that: Countermeasures are entitled to use when it is expected to provide more good than harm The criterion for introducing or withdrawing a countermeasures must be that it provides optimum protection for most of the population (ALARA ) Clean-up operation is effective only when a permanent reduction of the radiation can be achieved by a countermeasure The cost of countermeasures must be weighed against the benefits of this ICRP = internationella strålskyddskommissionen

8 Are there enough resources for urgent action after the deposition on agricultural land? Human resources; farmers, volunteers, military Material resources; Agricultural machinery (combines, tillage machines, etc.) Goods as fertilizer, lime, plastic

9 The man can do is... The man can do is Wait until the radioactive material disintegration - Often the best solution for the short-lived radionuclides 2. Move the radioactive material (such that the distance increases and the dose reduced) - Wash, rinse, scraping, cutting, transporting 3. Increasing the shielding around the radioactive substance (dose reduction) - Irradiation reduces - Diggning down, pour in etc.

10 Limits for foods on marketed products in EU

11 Countermeasures Countermeasures reduce the transfer of radioactive substances through the food chain to humans

12 Countermeasures 1. Warning stage - before the deposition 2. First year - after deposition - during the growing season 3. On long-term

13 Countermeasures 1. Before the deposition, warning stage Cs & Sr If possible: Harvest crops Set the animals indoor Cover crops Closes ventilation for animal housing Closes ventilation for drying of the crop Smoothing (utjämning) of plowed land

14 Countermeasures 2. After the deposition Cs & Sr Current season Reduce plant rot uptake Delay harvest Discard or throw away contaminated crop Future seasons Remove contaminated crop or a top layer of soil Fertilizer Liming, Sr Plowing Change varieties or crops Change the orientation of production or stop production

15 Deposition during various seasons During the first year Interception and retention of nuclides on vegetation at time when the fallout occurs Winter, spring, summer or autumn will determine what measures can be implemented During the following year radioactive nuclides (Cs and Sr) is transported mainly via the roots of plants

16 Example on food chains to man Cesium-137 and iodine-131 to GRASS -KO -MILK -MAN Källa: Andersson et al, 2001 One third of the deposition is calculated detained in pasture grass.

17 Transfer of 137 Cs from the plant animal - meat - man The calculations assume a daily intake of 10 kg DM pasture grass per animal per day, and the EU limit value 1250 Bq / kg whole-body effective radiation dose concerns. Transfer to meat is about 5-6 times higher than transfer to milk

18 Transfer to food by animals Föda Mag- tarmkanal Avfö ring Blod Urin ä V vnad Muskel, organ (Cs) Ben (Sr) ö Mj lk

19 Cs-134, Cs-137 The extent of absorption may be one of about 50% -80% and sometimes more With the blood are the subject quickly into the animal body, which then circulates At equilibrium estimated 85% of the total body content of Cs-137 present in muscle 5% of the bones and the rest in other organs or tissues Sr-90 Absorbed primarily in the small intestine (tunntarmen) The extent of absorption varies between 5% -25% in adult ruminants, while in young animals can be 100% absorption Sr-90 accumulates preferentially in the bones - about 95% of the body's content can be found where. Milk and to some extent meat is Sr sources in human diet Milk, meat and eggs are sources of caesium in the human diet

20 Reduce radioactivity during the growing season - Reduce the activity of growth (dilution) - Tillage and ploughing and so again - K-fertilization, Cs - Liming, Sr - Trim the grass or pasture - Harvesting grass or pasture with high stubble - Remove contaminated crops Cs & Sr

21 Reduce radioactivity during the growing season - Reduce the activity of growth (dilution) - Give activity time to reduce through growth - Wait until the radioactivity is transmitted through wind erosion and rainfall to the ground - Wait for the physical half-life has affected the crop (e.g. store crops containing iodine-131) Makes no Countermeasures but makes measurements

22 Reduce radioactivity during the growing season -K-fertilization (Cs) or liming (Sr) Potassium fertilization has an effect already during 1st year K-fertilization or liming are recommended for newly seeded or after ploughing Tive Gödsel-Jet. Rampspridare kombimaskin för konstgödsel och utsäde. It can be urgent during autumn or spring and just after the 1st cut of grass

23 Reduce radioactivity during the growing season Effect of K-fertilization on cesium uptake Barley, Bq/kg dw Grass 1st cut Bq/kg dw Bq/kg ts Cs-137 i Kornkärna Kaliumgödsling kg/ha/år The experiment shows the levels of cesium-137 in barley and grasses on 5 years

24 Reduce radioactivity during the growing season - Trim the grass or pasture Trim the grass or pasture is very effective method for smoothing and cut the old contaminated grass and tussocks Betesputsare; Kverneland FX, för borttagning av gammalt gräs och tuvor. Metoden är effektiv genom minskning av radioaktiv överföring till betande djur. Can become urgent!

25 Reduce radioactivity during the growing season and or remove different crops For quick removal of grass self-loading trucks or round baler or combine harvester is needed Inplastare. Grass Pasture Cereals Oilseeds Potatoes Other crops The method is very effective up to 90% of cesium can be removed but the countermeasures creates a waste problems

26 Reduce radioactivity during the growing season and or remove contaminated crops Cereals Cut and remove the crop - K-fertilization, Cs - Liming, Sr Plouging and sow again Harvest and remove the straw

27 Removal and disposal - of surface layer soil Possible method to scrape the soil and deposit it on or near the field Efficiency up to 90%, but the measure creates waste.

28 Removal and disposal - of top layer of roots or grass The top layer 3-5 cm of a grasscovered and the contaminated area is stripped and carried away

29 Removal and disposal - of contaminated snow Is urgent, but must be assessed in relation to cost Efficiency can be up to 90%, but the countermeasure creates waste Traktor med snöfräs

30 Change the orientation of production or stop production Growth of industrial crops as Salix, grass, straw, cereals - for bio - energy - ethanol - for heat power plants Change land to forestry

31 3. Countermeasures on long-term - year after deposition Plant root uptake of radioactive substances caused by: Nutritional status in soil ph in soil Root distribution in the soil profile Soil species -Clay - Organic content

32 Radionuclides in the agricultural cycle: Field Grödor Farm Skördeprodukter one cycle at the farm is through soil - plant - animal a cycle outside farm is through consumption of food Mark Djur, vegetabilier Kött, mjölk vegetabilier

33 Caesium is bound to large parts of the biological plant materials and minerals mineral soils organogenic soils In organogenic soils caesium binds weakly but in mineral soils (clay soils) Caesium binds strongly

34 Countermeasures on long-term Ploughing or tillage Removal and disposal of surface layer soil Trim the grass or pasture K- fertilization Liming

35 Environmental monitoring Specialgårdar in Chernobyl contaminated county in Sweden, Sampling points and medium depostion : Samples of ley, pasture grasses and cereals 1 m 2 cut at about 5 cm above the ground county Cs-137 kbq/m 2 Z 31 Y 43 X 126 C&U 58

36 Mean transfer of 137 Cs to pasture, leygrass (1st cut) and grain, grass, Bq/kg d.w Transfer of 137 Cs to grass and grain Pasture grass Ley grass Cereal grain grain, Bq/kg d.w

37 Radioecology Pools and processes in which radionuclides are involved in the soils Plant uptake Particles Weathering Ion-exchange Ion exch. sites Frayed edge sites Fixation Mycelium Soil solution Organic material Interlayer sites Migration Non-labile fraction Labile fraction

38 Structure of clay minerals, fixation The structure of one 2:1 illite minerals To the left, an expanding layer To the right of non-expanding layers

39 Migration studies of various undisturbed soil profiles sites county Soiltype Number of samples Hille X organic 7 Möjsjövik C organic 5 Skogsvallen U clay 7 Ramvik Y clay 5 Hammarstrand Z silt 5 Blomhöjden Z silt 4 S:t Blåsjön Z silt 5 Trödje X sand 2

40 Migration studies of various undisturbed soil profiles Sampling technique for Migration Studies A B C AUGER / cor 5 m 20 m 20 m Ulltuna augeer

41 Migration Studies of two different soil profiles Hille Skogsvallen 0 Relative activity (%/cm) Relative activity (%/cm) Hille i X-län, Organogen jord Cs-137 deposition 214 kbq/m 2 5 Skogsvallen i U-län, ler jord. Cs-137 deposition 97 kbq/m Depth (cm) Depth (cm)

42 Forest Radioecology The average monthly of Cs-137 in deer from Heby Municipality Jan, feb, mars, apr, maj, jun, jul, aug, sep, okt, nov, dec,

43 Forest Radioecology The average concentration of Cs-137 activity in moose from Heby municipality from 1986 to

44 Cs-137 concentrations in plants in different ecosystems after 1-5 years Agricultural forest bog pasture Animal, moos mushrooms

45 SLUT

46 Different developmental stages of cereals State of development is very important for crop uppfångningsförmåga..

47 Tabell 4.9. Beräknad genomsnittlig halt i mjölk av 137 Cs (Bq/l). Skuggade områden indikerar halter över gränsvärdet 1000 Bq/l Nedfallsnivå Tidpunkter kbq/m % fr spml* Tabell Beräknad genomsnittlig halt av 137 Cs (Bq per kg) i kött från mjölkko. Skuggade värden är över gränsvärdet på 1250 Bq/kg Nedfallsnivå Tidpunkter kbq/m % fr spml

48 Motåtgärder i svenskt jordbruk efter ett radioaktivt nedfall vid olika nedfallsnivåer och årstider Syfte : ta fram bättre underlag ge konkreta förslag på åtgärder i växtodlingen för att minska överföringen av radiocesium från olika grödor till bröd, kött och mjölk. Källa: Klas Rosén och Jan Eriksson Inst f mark och miljö, SLU

49 Ramar Arbetet hittills gäller Cs Fokus är på nedfallsåret (i detta sammanhang perioden från höst efter odlingssäsongen till slutet av nästa odlingsäsong) Behov av åtgärder relateras till EU:s gränsvärden för Cs-halter i livsmedel vid en framtida olycka (1250 Bq/kg)

50 Scenarier-nedfallsnivåer 10 kbq/m 2, medeltal Sverige vid Tjernobyl 100 kbq/m 2, mest belastade områden i Sverige vid Tjernobyl 1000 kbq/m 2, områden nära Tjernobyl

51 Scenarier-nedfallstidpunkter T0. Nedfall på vinterhalvåret utanför vegetationsperioden. T1. Ungefär 1 maj. Vid vegetationsperiodens inledning. Vid vårsådden av spannmålsgrödor. Tjernobylnedfallet skedde ungefär vid denna tidpunkt. T2. Ungefär 22 maj vid tidpunkten då djur släpps på bete. Utvecklingsstadium ca för höstvete och ca i slutet av perioden för vårkorn. T3. Ungefär 12 juni. Kring denna tidpunkt sker en stark vegetativ tillväxt hos vallfoderväxter och beten vilket gör att kapaciteten för uppfångning av nuklidnedfall är hög. Utvecklingsstadium ca för höstvete och ca för vårkorn. T4. Ungefär 10 juli. Slåttervallar är nu skördade och återväxer. Efter denna tidpunkt används skördade vallar för bete på en del gårdar. Utvecklingsstadium ca för höstvete och ca för vårkorn T5. Ungefär 1 augusti. Före en eventuell andra vallfoderskörd och före skörd av spannmål och oljeväxter. Utvecklingsstadium ca (mjölkmognad, börjar gulna) för höstsådd och ca för vårsådd spannmålsgröda. T6. Ungefär 1 september. Skörd av höstsäd avslutat. Skörd av vårsäd och upptagning av potatis.

52 Exempel: Slåttervall som används till mjölk och köttproduktion för vinter utfodring Tabell 4.8. Beräknad genomsnittlig halt av 137 Cs (Bq/kg ts) i vall Nedfallsnivå Tidpunkter kbq/m 2 1, 1 maj 2, 22 maj 3, 12 juni 4, 10 juli 5, 1 aug Förstaskörd: Andraskörd:

53 Val av motåtgärder Vad är möjligt? Vad är realistiskt? Fördelar Nackdelar Framtida effekter

54 Motåtgärdsmatris Tabell Motåtgärdsmatris. Vallfoder till mjölkkor. Nedfall Tidpunkter kbq/m (1) * ingen åtgärd 100 (6) * ingen åtgärd 1000 (11) * plöj och så nytt * kaliumgödsla * hög stubbhöjd * slå av, för bort * energigröda * träda (2) * ingen åtgärd (7) * ingen åtgärd (12) * kaliumgödsla * slå av, för bort * energigröda * träda (3) * ingen åtgärd (8) * slå av, för bort * energigröda * träda (13) * slå av, för bort * energigröda * träda (4) * ingen åtgärd (9) * kaliumgödsla * hög stubbhöjd * energigröda (14) * kaliumgödsla * plöj och så nytt * hög stubbhöjd * energigröda * träda (5) * ingen åtgärd (10) * slå av, för bort * energigröda (15) * slå av, för bort * plöj och så nytt * energigröda * träda

55 Grödor Gröda Vårsäd Höstsäd Vårsäd Höstsäd Vall-vinterutfodring Vall-bete Stråsäd och vall Vårsäd Naturbete Oljeväxter Potatis Livsmedel Bröd Bröd Griskött Griskött Mjölk Mjölk Kött mjölkkor Kött kvigor, tjurar intensiv Kött kvigor, tjurar extensiv Inga överföringsfaktorer att finna Potatis, chips, pommes frites

56 Året efter nedfall Jordtyp Stråsäd Vall, oplöjd Vall, plöjd Bete, natur Vall oplöjd Vall, plöjd Bete, natur Bröd Griskött Mjölk Mjölk Mjölk Nötkött Nötkött Nötkött Kritiskt värde Nedfallsnivå av 10 kbq per m 2 Lerjordar 0,5 0, Leriga jordar Mull/sandjordar Nedfallnivå av 100 kbq per m 2 Lerjordar Leriga jordar Mull/sandjordar Nedfallnivå av kbq per m 2 Lerjordar Leriga jordar Mull/sandjordar

57 Effects of countermeasures on Cs-137 levels in milk and meat Meat Milk Level of pasture contamination (Bq/kg) *Intake/da y (kbq) Caesium-137 level equilibrium (Bq/kg) Caesium-137 level following boli (Bq/kg) Caesium-137 level equilibrium (Bq/kg) Caesium-137 level following boli (Bq/kg) , , , , , , , , ,200 1,400 1, , ,000 3,000 2, , ,000 4,600 5,600 1,860 The table illustrates the relationship between levels of pasture contamination and caesium-137 levels in meat and milk, and the effect on meat and milk levels of administering boli. *Assumes daily intake of 70 kg fresh herbage/animal.

58 Emergency exposures Operativa guidance Operations shall always be justified and optimised, i.e. provide maximum benefit Emergency Emergency Emergency 0-50 msv Actions skall be justified and optimised, msv Only volunteers. Not women in fertile age if pregnancy cannot be ruled out. (SSI) msv Only volunteers, In life-saving actions. Not women in fertile age. Good knowledge of radiation risks needed. (SSI) Over 500 msv Only if benefits for others clearly outweigh the risk for the rescue worker (ICRP) Dose msv Källa: Robert Finck

59 Research group for tersest radioecology at SLU Agricultural ecosystem - - important food chains - - countermeasures Forest ecosystem - - nutrient-poor systems - - mushrooms, moos - -(fish) Dynamic models Natural radionuclides - in meadow- and pasture- land (Reindeer)