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Canadian Nuclear Commission canadienne Safety Commission de sret nuclaire Canadian Benthic Data Set Canadian Benthic Data Set S teve Mihok S teve Mihok EMRAS II Meeting, Vienna, Austria January 27, 2010 EMRAS II Meeting, Vienna,

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Canadian Benthic Data Set Canadian Benthic Data Set

S teve Mihok EMRAS II Meeting, Vienna, Austria January 27, 2010 S teve Mihok EMRAS II Meeting, Vienna, Austria January 27, 2010

Canadian Nuclear Safety Commission Commission canadienne de sûreté nucléaire

nuclearsafety.gc.ca nuclearsafety.gc.ca

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EMRAS II Meeting, Vienna, Austria January 2010

Thompson et al. (2005) Thompson et al. (2005)

12 contaminants, As, Cr, Cu, Mo, Ni, Pb, Se, U, V, Pb-210, Po-210, Ra-226 (N=1,020 - 2,269) Uranium mining regions with co-located benthos sampling & organic depositional sediments 132 Ontario & Saskatchewan sites 190 genera and/or species Criteria/methods follow Persaud et al. (1992) as used for Ontario LEL / SEL guidelines (As, Cr, Cu, Ni, Pb) 90th percentile SSLC for each taxon 5th percentile LEL, 95th percentile SEL calculated No curve fitting, no dose calculations

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EMRAS II Meeting, Vienna, Austria January 2010

Original Methods Original Methods

“Weighted” percentile as in Persaud et al. (1992), also calculated “closest observation” percentile (SPSS) Weighted value typically higher Uranium LEL 104 vs 32, SEL 5,874 vs 3,410 ug/g Six data selection criteria Minimum of 10 sites per taxon, lost considerable data Concentration range 2 orders of magnitude (V, Cr x) Spatial range (35 reference sites, 97 contaminated) Mainly benthic species (81% defined as infaunal) Minimum of 20 SSLCs for LEL/SEL calculation Data mean ~30 for SSLCs, LEL/SEL range N=28-59

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EMRAS II Meeting, Vienna, Austria January 2010

Interpretation Interpretation

LEL/SEL values highly sensitive to exact percentile calculation method, large effect on Uranium values “Good” predictions of “no impacts” with weighted LELs, “Poor” predictions for many SELs (21 sites) Exploratory data analysis with multiple contaminant indices or data subsets was not informative (As & Ni associated with uranium deposits in Saskatchewan) Radionuclide thresholds differ from ERICA model predictions of potential impacts, Why? Hardly any data on contaminant concentrations in benthos vs sediments, just a few taxa sampled

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EMRAS II Meeting, Vienna, Austria January 2010

Benthos - Radiation vs Metals? ? Benthos - Radiation vs Metals? ?

Control Umine site

600 0.6 – 0.8 Po-210 80 0.5 - 0.9 Pb-210 0.6 0.1 – 0.6 Ra-226 Benthos equivalent at 10 µGy/h (ERICA) LEL range Thompson et al. 2005 Sediments Bq / g dw % of Community

?

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EMRAS II Meeting, Vienna, Austria January 2010

Example of Uranium SSLC’s Example of Uranium SSLC’s

32 Mean sample size for SSLC 21 Median sample size for SSLC 1683.2 1319.8 SD SSLC 1064.9 693.5 Mean SSLC (ug/g) 5874.1 3410.0 SEL (ug/g) 104.4 32.0 LEL (ug/g) Weighted Intuitive N=56 Taxa Ont+Sask + Bancroft URANIUM

URANIUM

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EMRAS II Meeting, Vienna, Austria January 2010

Discussion: Dose Calculations Discussion: Dose Calculations

Abundance Site-specific? Site-specific? Retention % = Daughter? Abundance = Parent? Abundance Issues 96% 70% X 74% X 99% X 96% X 96% Data Notes

U-235 (?) Po-210 Bi-210 Pb-210 Rn-222 Ra-226 Th-230 U-234 Th-234 U-238

DCF n/a Nat uran 2% CRITICAL 23 - 0 = % Ra-226 0 -13 = Pb-210 0 - 1 = % Ra-226 CRITICAL 24 - 59 @30%? Ra 20 -1 Measured 10 - 0 = Ra-226? DCF 12 - 0 Nat uran 49% External 0 - 26 =U-238? DCF 11 - 0 Nat uran 49% I – E % Approach Calculations, % Dose I-E example Greer Lake 2004

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EMRAS II Meeting, Vienna, Austria January 2010

Greer Lake 2004 “PSL2” Chironomid Greer Lake 2004 “PSL2” Chironomid

Measured U-238 / Th-230 at equal activity Ra, Pb, Po at 2x U / Th values, Radon estimated @30% Alpha RBE 40, Amiro (1997) DCFs [Tailings present in lake] Internal Dose 2,538 uGy/h

U-238 Th-234 (=U- 238) U-234 Th-230 Ra-226 Rn-222 = 30% Ra Pb-210 Bi-210 (=Pb- 210) Po-210 (=Pb-210)

External Dose 36 uGy/h

?

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EMRAS II Meeting, Vienna, Austria January 2010

Reference Lakes - Not in equilibrium Reference Lakes - Not in equilibrium

Internal Dose 12.1 uGy/h (alpha RBE of 40) Internal Dose 2.6 uGy/h Schmoo Lake 2002 Po/Pb = 2x U-238, 10x Th-230, 6x Ra-226 Fulton Lake 2004 Po/Pb = 4x U-238 / Th-230 2x Ra-226

U-238 Th-234 (=U- 238) U-234 Th-230 Ra-226 Rn-222 = 30% Ra Pb-210 Bi-210 (=Pb- 210) Po-210 (=Pb-210) U-238 Th-234 (=U- 238) U-234 Th-230 Ra-226 Rn-222 = 30% Ra Pb-210 Bi-210 (=Pb- 210) Po-210 (=Pb- 210)

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EMRAS II Meeting, Vienna, Austria January 2010

Decisions (May need a Radon DCF? ) Decisions (May need a Radon DCF? )

2% nat uranium ~30% missing, calculated @~2x? = Pb-210, not critical to dose? ~30% missing, calculated @~2x? ? % retained ? Decision critical = Measured or parent = daughter or parent - Decision? 49% nat uranium = daughter or parent - Decision? 49% nat uranium (DCFs vary ±) RBE = 10, DCFs for insect larvae & bivalve mollusc ~ same? ERICA Tool – Internal + External?

U-235 Po-210 Bi-210 Pb-210 Rn-222 Ra-226 Th-230 U-234 Th-234 U-238

Included in U-238 Measured or = radon = Pb-210 Measured or = radon @30% Ra (~ vert bone) = Measured = daughter Included in U-238 Not included = Natural Uranium SA? Alpha RBE 40, Amiro DCFs, generic benthos PSL2 Internal Calc

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EMRAS II Meeting, Vienna, Austria January 2010

Discussion: Improving SSLCs ? Discussion: Improving SSLCs ?

Curve-fitting to obtain SSLCs

Chironomus - Arsenic (N=97)

2 4 6 8 10 12 14 16 18 20

3 . 1 . 5 . 9 1 . 3 1 . 7 2 . 1 2 . 5 2 . 9 M

e log Sediment concentration Frequency 0% 20% 40% 60% 80% 100% 120% Frequency Cumulative %

Even this large data set is not a good fit to log distribution? 90th percentile is in the flat part of CDF and may remain as poorly defined?

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EMRAS II Meeting, Vienna, Austria January 2010

Statistical Interpretation Statistical Interpretation

Curve fitting to obtain LEL/SEL thresholds (5%) will also be affected by small sample sizes Bootstrapping for confidence intervals, what to do about outliers (e.g. very high Uranium in Link Lakes) Sensitivity Analysis (sites, SSLCs, taxonomic groups) Multivariate analyses for interactions among metals and radionuclides, “fingerprints” for severe effects? Prospects for more data Objectives to be defined Path forward on data / analysis … J. Garnier LaPlace

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EMRAS II Meeting, Vienna, Austria January 2010

A question from WG 4 on Tuesday A question from WG 4 on Tuesday

The Biota modeling group will be estimating dose to fish and benthic invertebrates at Beaverlodge for the next mid-term EMRAS meeting. Is there any interest in modeling population effects, e.g. for lake whitefish and/or fingernail clams (Pisidium spp.)?