Page History
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Technical issues related to the ERICA Tool (on Facilia website)
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Posted: 20/10/2010
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Wildlife transfer
From:
Marko Černe
Jožef Stefan Institute
Slovenia
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3) If CR values are in the range from 61 to 493 for one fish for Ra, what should I do? Should I use average or maximum? N of samples is 15.
Answer:
1. Yes Yankovich et al. 2010 presents the most up to date compilation of tissue:wholebody activity concentration ratios you can use these to convert tissue specific activity concentrations to wholebody values. Note the Yankovich et al. paper has been published today (26/10/10) in an issue of Radiation and Environmental Biopyhsics see http://www.springerlink.com/content/0301-634x/49/4/.
2. May Might depend upon the radionuclide: you may want to convert both bone and muscle data and take average for radionuclides which do not accumulate in either of these tissues; for other radionuclides which accumulate in one of the two tissues you may have more confidence in the data for the accumulating tissue (e.g. Sr, Pu, Am and Ra accumulate in bone and have comparatively low transfers to muscle).
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Posted: 12/10/2010
Predicting future biota and media concentrations
From:
Chutarat Saengkulž
Burapha University
THAILAND
Question:
I would like to predict of radiocesium activity in fish and water in the future using the ERICA Tool. How can I do this?
Answer:
You cannot use the ERICA Tool (or other packages such as RESRAD BIOTA) to make future predictions of water and fish activity concentrations.
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Question:
I have a problem about putting data into the ERICA Tool - I have many data for cesium-137 concentrations in water and fish from 1962-2006 but I cannot put all data in ERICA Tool. Now I can input one data point from one year to calculate the absorbed dose rate. Please advise me about how to input such data into Tier 2 of the ERICA Tool.
Answer:
Currently, you cannot input time series data, or data for more than one location, into the ERICA Tool to model in a single run. This functionality is something which has been requested previously by users and it MAY be provided in future Tool versions.
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Question:
I am trying to apply the ERICA Tool to plants. If a plant, such as the Marsh Marigold, has a large leave on top of the stem - what dimensions should be used?
Answer:
To be honest perhaps the plant geometries have not been well thought out to date - they do not really represent whole-organisms as perhaps implied by documentation accompanying the ERICA Tool. The grass geometry in the ERICA Tool is taken from the ICRP Wild Grass RAP and is a 'grass spike'; no in soil dose rates are estimated only above ground. If you are concerned that the default plant may not adequately represent the species you want to assess then have a play with the create organism function of Tier 2 or 3: create an organism to represent your marigold leaf and compare DCC values to the default grass. We'd be interested to hear what you find.
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Question:
In the ERICA Tool are the all of the DCC values estimated using the same methodology or is Monte-Carlo simulation used on for terrestrial organisms?
Answer:
The key factor in the estimation of DCC is the absorbed fraction, and this is always calculated by Monte Carlo simulation using a phantom geometry. The only difference is that, historically, in FASSET, the aquatic and terrestrial formulas were calculated by two different Monte Carlo methods, but for ERICA the Ulanovsky and Proehl sphericity method (see ERICA papers) was adopted for everything, after having checked that, for aquatic organisms, both methods gave very similar results.
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From:
Susan Schneider
Serco
UK
Question:
In the aqueous (ie marine and freshwater) environments, I can see how the dose rates relate to fractions of time spent in-sediment and in-water, and to water and sediment concentrations (using the distribution coefficient Kd).
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Please can you clarify in Tier 2 how ERICA uses the input occupancies (of which there are four, in-sediment, sediment-surface, in water and water-surface).Answer:
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<span style="color: #ff0000"><strong>Answer:</strong></span>
_In Tier 2 you can select the occupancy factors to be what you want - these are used to determine the external exposure only. The dose rate at water surface will be 50 % of that in water column. The DCCs for sediment and water are the same. For sediment-water interface the dose rate is (\[0.5*DCC_external*sediment activity concentration\]+\[0.5*DCC_external*water activity concentration\])._ _The DCCs for sediment and water are the same._ _See response posted to question (from Marko Černe) below re how occupancies are (not) used in estimatation of internal dose rate._ |
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From:
Susan Schneider
Serco
UK
Question:
Please can you clarify about contaminated air.
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Has this dependence on air concentration been removed in this more recent version of ERICA (I had previously used the prototype version, in Dec 2006)? Is the chronic atmospheric release only relevant when using the transport models?
Answer:
For H, C, S and P air concentrations are the input rather than soil concentrations. ERICA uses a specific activity approach to then estimate biota concentrations of C&H (there's an article by Galeriu et al describing this). This is in-line with approaches taken for human assessment (e.g. see IAEA 2010 TRS472). Honest answer to S and P is that ERICA adopted parameters from R&D128.
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From:
Susan Schneider
Serco
UK
Question:
My question is about terrestrial occupancies in ERICA, which I would like to clarify for a report I am writing. In the database, terrestrial DCCs are provided for three habitats, in-air, in-soil and on-soil. However in the ERICA Help, only two terrestrial habitats are defined in Figure 5. Habitat 6 must be In-soil, but is habitat 5 On-soil or In-air? Is it assumed that air-borne contamination is insignificant? (I am using media concentrations, not the transport models provided in ERICA). Surely the In-air habitat would need to be included for eg birds and flying insects?
Answer:
You are correct in saying that Figure 5 shows only two habitats for terrestrial ecosystems - Habitat 5 is 'on-soil'. However, you are able to consider flying organisms and a fraction of time in-air can be defined in Tiers 2 and 3 for some organism types - 'Occupancy Factors and Radiation Weighting Factors' screen. There are some limitations on sizes of organisms for which in air dose conversion coefficients can be calcuculated using the create organism wizard (see Table 10 of the Help file). Note the dose rate estimated to a flying animals is that from contaminated soil and not contaminated air. There is no consideration of external dose rates from contaminated air in the ERICA Tool (nor is it considered in either R&D128 (exception being noble gases) or RESRAD-BIOTA). The in-air habitat is not shown on Figure 5 as this presents the habitats consider during the estimation of the Environmental Media Concentration Limits used in Tier 1; these only consider the scenarios likely to give the highest dose rate.
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