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Introduction to the ERICA Tool
Centre for Ecology & Hydrology - Lancaster October 2011
David Copplestone & Nick Beresford
ERICA project objective
“to provide and apply an integrated approach of addressing scientific, managerial and societal issues surrounding environmental effects of ionising contamination, at a community level, with emphasis on biota and ecosystems”
The ERICA Tool (http://www.erica-tool.com/) is the freely available software which implements the ERICA integrated approach.
To download Tool:
http://www.project.facilia.se/erica/download.html
Well documented:
https://wiki.ceh.ac.uk/display/rpemain/ERICA+reports
Considers terrestrial, freshwater and marine ecosystems
www.ceh.ac.uk/PROTECT
ERICA flow chart
ERICA Integrated Approach
Concentration screening value
Dose rate screening value
Detailed analysis and evaluation of data. Interaction and supplementation with all relevant databases
Extrapolation (e.g. population, ecosystem)
Management Assessment Tool CharacterisationManagement Assessment Tool Characterisation
Tier 3
Site-specific
Probabilistic analysis
Tier 2
Tier 1
Sta
keho
lder
Invo
lvem
ent
Issues
and
options
Plan
Evaluation of assessment
April 2006
Problem formulation
Exit
Exit
www.ceh.ac.uk/PROTECT
Elements of assessment
Media concentration
Release
Dose rate
Risk
Dispersion model
Transfer model
Dosimetry model(internal exposure)
Wholebody activity concentrationsDosimetry model
(external exposure)
Effects understanding/ numerical benchmark
What are protection goals?
Clear goals shape Swedish environmental policy………………………. The overall goal is to pass on to the next generation a society in which the major environmental problems have been solved. …………………………….
What are protection goals?
GOAL
A condition or state desired to be brought about through a course of action program. They are usually qualitative statements that provide direction for plans and projects. Goals are not specific numerical limitations, but conditions or states which can be obtained through careful planning and implementation.
The water use goal for the fishery, established by the Hamilton Harbour Stakeholder Group, is "that water quality and fish habitat should be improved to permit an edible, naturally-reproducing fishery for warm water species, and water and habitat conditions in Hamilton Harbour should not limit natural reproduction and the edibility of cold water species."
So - what are protection goals?
…….. a term which is inconsistently used!
But obviously need to know what you want to protect before conducting an assessment/setting dose rate benchmarks
- what is protecting the environment? …. There appears to be no internationally agreed definition.
How are protection goals being defined in radiological protection/what’s driving the need for assessment ?
Typical radiological protection goal definition
For instance (from EC PROTECT project): To protect the sustainability of populations of the
vast majority of all species and thus ensure ecosystem function now and in the future. Special attention should be given to keystone, sentinel, rare, protected or culturally significant species
Stakeholder involvement: what do we mean by stakeholders?
Term stakeholders here means: any person or organisation that could either be
affected by, or interested in, the outcome of a decision
Consequently Will vary with the objective of the assessment May include a wide range of people (experts, lay
people, elected people, volunteers, etc)
What is Problem Formulation?
Identifies the: source (of radionuclides) receiving media any key receptor species assessment criteria to use uncertainties (either knowledge or data)
Considers the need for, and takes into account, stakeholder
involvement legislation and/or any regulatory requirements
Problem formulation... Should be documented
in a transparent & understandable way
Commonly, by conceptual model describing what is known about the site
Level of detail required will be influenced by a number of factors
www.ceh.ac.uk/PROTECT
Elements of assessment
Media concentration
Release
Dose rate
Risk
Dispersion model
Transfer model
Dosimetry model(internal exposure)
Wholebody activity concentrationsDosimetry model
(external exposure)
Effects understanding/ numerical benchmarkTier 1
Tier 1 – a simplified screening tier Designed to be simple and conservative
User only needs to input media activity concentrations Aims to identify sites of negligible concern, removed from further
assessment – with a high degree of confidence Envisaged that most sites will only need this level of assessment
[i.e. ‘be screened out’]
www.ceh.ac.uk/PROTECT
Dose rate screening value Dose rate below which it is agreed (for the
purposes of an assessment) that there is no requirement for further evaluation
In ERICA Tier 1 input media (soil, water, sediment) activity concentrations are compared to precalculated concentrations estimated to give rise to the screening dose rate for the most exposed organism These are termed ‘Environmental Media
Concentration Limits’ (EMCL)
www.ceh.ac.uk/PROTECT
Required inputs – Tier 1 Maximum measured or
modelled media concentrations Terrestrial ecosystem - soil
(or air for a few radionuclides) Aquatic ecosystems – water
and/or sediment If no measurements but site
release estimates then Tool has simple dispersion models
www.ceh.ac.uk/PROTECT
Reference organism? Vast number of potential
organisms to simplify a set of organisms have been selected to represent different tropic levels, organisms likely to be exposed, radiosensitive organisms, encompass all European protected species, incorporate ICRP RAPs These are the ‘Reference
Organisms’ 12 freshwater, 13 terrestrial,13
marine organisms
TerrestrialAmphibian Bird Bird egg Detritivorous invertebrateFlying insects GastropodGrasses and herbs Lichen and bryophytesMammal ReptileShrubSoil invertebrateTree
www.ceh.ac.uk/PROTECT
Risk Quotient (RQ)
Sum of RQs adds together the RQs for the radionuclides (may be for different organisms)
If RQ>1 then screening dose rate exceeded (under these conservative assumptions)
Tier 2 – create organism
Common Lizard characteristics:Size (cm) - 14 length x 1 width x 2
depth
Weight - 10 g Occupancy - 50% in soil/50% on soil
www.ceh.ac.uk/PROTECT
Elements of assessment
Media concentration
Release
Dose rate
Risk
Dispersion model
Transfer model
Dosimetry model(internal exposure)
Wholebody activity concentrationsDosimetry model
(external exposure)
Effects understanding/ numerical benchmark
www.ceh.ac.uk/PROTECT
Transfer model
Very simple:
Default values derived from literature review
Assumptions (‘extrapolation’) made where no data
))m (Bq air or )dry weight kg (Bq soil),l (Bq water(filtered media ionconcentratActivity
weight)fresh kg (Bqbody wholebiota in ionconcentratActivity CR
3-1-1-
-1
)l (Bq waterfiltered in ionconcentratActivity
)dry weight kg (Bq sedimentin ionconcentratActivity )kg (l K
1-
-11-
d
www.ceh.ac.uk/PROTECT
RQ at Tier 2
www.ceh.ac.uk/PROTECT
Tier 3 distribution
Assume lognormal for all Soil
Am-241 300±50 Bq/kg Cs-137 9500±5000 Bq/kg
Deer Am-241 1±0.5 Bq/kg Cs-137 5000±400 Bq/kg
www.ceh.ac.uk/PROTECT
Rules for estimating organism activity concentrations - aquatic ecosystems
Input water and sediment concentrations Biota concentration estimated as water conc. x CR Sediment used in external dose calculation
.... But if do not have water concentrations – what then? Water concentrations estimated as biota conc./CR
and/or sediment conc./Kd Missing biota and/or sediment concs then estimated
using predicted water concs and CRs & Kd respectively
www.ceh.ac.uk/PROTECT
Rules used in Tier 2 [new!] Freshwater ecosystem Select Pu-240 & all organisms No water data but have sediment (n=20),
fish (n=50) & amphibian (n=25) activity concentrations
Sediment 8000 Bq/kg DM (70% DM content) Fish 1E-1 Bq/kg FW Amphibian 1E-3 Bq/kg (FW)