Application of Biota Assessment Approach to a Site With a Past - PowerPoint PPT Presentation

Application of Biota Assessment Approach to a Site With a Past Uranium Mining and Milling Activities Marko Černe, Borut Smodiš The Third Technical Meeting on Environmental Modelling for Radiation Safety, IAEA, 24 – 28 January 2011

OUTLINE  INTRODUCTION → Former uranium mine, biota assessment approach  MATERIALS AND METHODS → field work, assessment with ERICA Tool  RESULTS → Dose rates to biota , radiological risk to biota  CONCLUSION

INTRODUCTION  Uranium mining and milling activities in Slovenia were in full operation from 1985 to 1990 when 600.000 tons of uranium ore were processed during that time  The mine has two disposal sites with U-mill tailings deposited at the Boršt and and red mud with spoil and lower grade ore at the Jazbec site

 Emission of natural radionuclides to the nearby habitats has often occured due to flow of tailings and mine waters to the local streams ( Todraščica and Brebovščica ) Brebovščica stream Todraščica stream U-mill tailings Red mud with spoil and lower The mine entrance grade ore

Mill tailings disposal site: 0.6 Mt (375,000 m 3 , 4.11 ha) of hydro- metallurgical tailings (residue of U ore processing: SiO 2 , 2- salts): CaCO 3 , SO 4 1.0 Bq/g 238 U, 4 Bq/kg Minor waste rock piles: 230 Th and 8.6 Bq/g 70 kt, 143 kt 226 Ra Waste rock pile: 1.5 Mt of waste rock plus red mud (50 kt; precipitate of U leaching solution produced by neutralisation with lime): CaSO 4 , Fe(OH) 3 , 0.5 Bq/g 238 U, 62 Bq/g 230 Th and 0.2 Bq/g 226 Ra Panoramic view at the Žirovski vrh area, size 4 x 4 km – view towards south

 Mine area was under constant monitoring surveillance from the beginning of mine operation, with aimed to measure critical radionuclides, such us U-238, Ra-226 and Pb-210 in water, sediment, soil, fish and lichens  Due to long-term radioactivity discharge to the local streams the potential radiological risk to frehwater and terrestrial biota could be observed  Biota risk assessment should be performed

MATERIALS AND METHODS  ERICA Tool, level Tier 2 was applied for the biota risk evaluation  Native aquatic and terrestrial species, such us Brown trout, Stone crayfish, Soft rush, Marsh marigolds and Tall Moor Grass were assumed as target organism exposed to potential radiation impact  Ra-226, U-238 and Pb-210 for aquatic biota and Ra-226, U-238 and Th-230 for plants were included in the assessment  Monitoring data were used as input data for the assessment

 A case of assessed biota in the vicinity of a former uranium mine Brown trout Stone crayfish Tall Moor Grass Marsh marigolds Soft rush

Tailings pile Sampling site for tailings waters Todraščica stream Contaminated marsh Contaminated marsh Sampled plants Contaminated marsh Tailings pile

 Monitoring and ERICA default CR values were applied in the model  The screeening dose value of 400 µG h⁻¹ was used in the assessment as recommended by the IAEA and U.S. DOE for aquatic organisms and terrestrial plants  Target organisms used in the model were created using real geometry and mass data

RESULTS  Aquatic biota → total dose rates per organism

 Aquatic biota → total dose rates per organism

 Terrestrial plants → total dose rates per organism

 Biota risk evaluation - no environmental risk from ionising radiation to aquatic and terrestrial biota was observed as screening value 400 µ Gy h⁻¹ was not exceeded  Stone crayfish would be exposed to environmental risk in the case of ERICA screening dose value (10 µ Gy h⁻¹) but in our case this would be negligible due to application of higher dose limit for the assessed organisms

CONCLUSIONS  Assessment revealed that no environmental risk to aquatic biota and terrestrial plants was observed due to radioactivity discharge into the local streams  Predicted dose rates to aquatic biota were the highest during the mine operation in both streams  Todraščica stream resulted in higher biota dose rates compared to Brebovščica stream  Stone crayfish received evidently higher dose rate compared to Brown trout

 Soft rush received the highest dose rate among terrestrial plants  Other organisms should be assessed due to their presence in the local streams  Application of other models is suggested to compare the results

4,0E-05 3,5E-05 3,0E-05 koncentracija (Bq/m3) 2,5E-05 2,0E-05 1,5E-05 1,0E-05 5,0E-06 0,0E+00 2001 2002 2003 2004 2005 2006 2007 2008 leto U-238 Ra-226 Average yearly concentrations in air at the Todraž site

7 5 6 4 3 2 1 Sampling sites for Rn using track detectors (FK, Karlsruhe)

12 11 Koncenntracija rudniškega radona (Bq/m3) 10 9 povprečna vrednost 8 7 6 5 4 3 2 1 0 Povprečje 2000 2001 2002 2003 2004 2005 2006 2007 2008 1993- 1999 leto Contribution of the mine Rn

45 40 Koncentracija radona (Bq(m3) 35 30 25 20 15 10 5 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 leto Todraž Gor. Dobrava Dol. Dobrava Gorenja vas Ljubljana Average yearly Rn concentrations using charcoal adsorbers

140 120 MP Jazbec 3 ) MP Boršt Koncentracija radona (Bq/m 100 80 60 40 20 0 2004 2005 2006 2007 2008 Leto Rn concentrations (track detectors) at two waste piles

300 250 3 ) Koncentracija (Bq/m 200 150 100 50 0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Brebovščica Todraščica Brebovščica - povprečje Todraščica - povprečje Average yearly concentrations of U in Brebovščica and Todražčica streams

40 35 30 3 ) Koncentracija (Bq/m 25 20 15 10 5 0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Brebovščica Todraščica Brebovščica - povprečje Todraščica - povprečje Average yearly concentrations of Ra in Brebovščica and Todražčica streams

40 35 30 3 ) Koncentracija (Bq/m 25 20 15 10 5 0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Brebovščica Todraščica Brebovščica - povprečje Todraščica - povprečje Average yearly concentrations of Pb-210 in Brebovščica and Todražčica streams

30 25 Koncentracija (Bq/m3) 20 15 10 5 0 2001 2002 2003 2004 2005 2006 2007 2008 Leto U-238 Ra-226 Pb-210 Concentrations in one of the wells

160 140 120 Koncentracija (Bq/kg) 100 80 60 40 20 0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Brebovščica po Todraščica po Brebovščica po-povprečje 1994 - 2008 Sora po Activity concentrations of U-238 in sediments

700 600 500 Koncentracija (Bq/kg) 400 300 200 100 0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Brebovščica po Todraščica po Brebovščica po-povprečje 1994 - 2008 Sora po Activity concentrations of Ra-226 in sediments

500 450 400 Koncentracija (Bq/kg) 350 300 250 200 150 100 50 0 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Leto Brebovščica po Todraščica po Brebovščica po-povprečje 1994 - 2008 Sora po Activity concentrations of Pb-210 in sediments

20 18 16 14 Efektivna doza (µSv) 12 10 8 6 4 2 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 Leto Effective dose due to inhallation of long-lived radionuclides

300 250 Efektivna doza (µSv) 200 150 100 50 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 Leto Effective dose due to inhallation of short-lived Rn progenies

35 30 25 Efektivna doza (µSv) 20 15 10 5 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 Leto Effective dose due to drinking river water

0,4 Povprečje 0,35 0,3 Efektivna doza (mSv) 0,25 0,2 0,15 0,1 0,05 0 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 Leto Overall effective dose due to RŽV

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