Page History

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Technical issues related to the ERICA Tool (on Facilia website)

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Posted: 14/12/2010

CRs and occupancy factors for fish in the ERICA Tool

From:
Marko Černe
Jožef Stefan Institute
Slovenia

Question:
The CR value for Pb (300, IAEA, Safety report series no 19) in ERICA Tool is the same for benthic and pelagic fish. How is the internal dose estimated in the tool as the uptake of Pb should be different between benthic and pelagic fish? Internal dose depends only on CR value and is more or less related to uptake from water as the CR values are a ratio between biota concentration and water and not biota concentration and sediment? The contribution of feeding habitats to the internal dose is possible only in RESRAD-BIOTA? Barbarel that feeds with small invertebrates on the bottom of river is definitely exposed to higher internal dose. RESRAD-BIOTA should handle this.

If we use 100% occupany at the sediment-water interface for a benthic species of fish, does the tool calculate the dose only from sediment? If we do not have the sediment data, but we have the water data and 100% occupancyat the water-sediment interface, how does the tool deals with this?

Answer:
When the ERICA database was derived those responsible for deriving the freshwater CR values assumed (pressumably because of a lack of available data at that time) the the concentration ratio (which estimates the activity concentration in fish simply from that in water) were the same for benthic and pelagic fish. Therefore the estiamted whole-organism Pb-210 activity concentration in the benthic and pelagic fish will be identical. The internal dose rate will be similar for the two fish as difference in their geometry does not result in large variation in DCC values.

The allometric foodchain modelling functionality available in RESRAD-BIOTA is not applicable to fish.

_If you assume that an organism is at the sediment water interface the external does rate is estimated as:
0.5*DCCexternal*sediment activity concentration + 0.5*DCCexternal*water activity concentration; sediment will generally contribute the most to the total external dose rate. If you do not have sediment activity concentrations to input these will be estimated from kd and input water activity concentrations._

Answered by Nick Beresford 15/12/2010

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Posted: 13/12/2010

ERICA Tool create organism wizard - how are dimensions and mass used?

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