Download Ecosystem processes - challenges for radioecology

Ecosystem processes - challenges for
radioecology
Clare Bradshaw
Dept. of Ecology, Environment and Plant Sciences (EMB)
Stockholm University, Sweden
[email protected]
CERAD kick-off meeting, Oscarsborg Fortress, Oslofjord, April 17-19 2013
Who am I?!
My particular interest / focus
• Understanding the role of ecology in determining
the fate/effects of contaminants, including
radionuclides/radiation
– Mainly through experiments using ecologically
relevant scenarios, but also field studies
• Raising the profile of / critically addressing such
issues and looking for ways to incorporate such
knowledge in a practical way into risk
assessment, management
– e.g. IUR Ecosystems Approach Task Group
”Environmental protection”
Are we protecting ecosystems?
ICRP 2007:
Aim: “… preventing or reducing the frequency of such
radiation effects to a level where they would have a negligible
impact on the maintenance of biological diversity, the
conservation of species, or the health and status of natural
habitats, communities and ecosystems”.
IAEA 2003:
“…to safeguard the environment by preventing or reducing the
frequency of effects likely to cause early mortality or reduced
reproductive success in individual fauna and flora to a level
where they would have a negligible impact on conservation of
species, maintenance of biodiversity, or the health and status
of natural habitats or communities”.
Ecosystems
are complex!
Resources
Physical conditions
organisms/populations
Current situation
Ecosystem processes: include effects and fate/exposure
• In both cases, often a lack of ecological and/or
environmental realism
• We base legislation and guidelines aimed at protecting
ecosystems on data from
– single species/individuals
– equilibrium conditions
– and/or (even worse ) purely physics and chemistry
• Bottom up thinking (small scale to large scale, simple
to complex, extrapolation) – why not the reverse?
State of the art: fate/exposure
•
•
•
•
•
Lots of field measurements (esp Cs)!
Lots of chemistry, not much biology/ecology
Heavy focus on using (e.g.) Kd, CR...in predicting/modelling
Lab studies rarely include biological/ecological factors
Some steps being made to include more complexity
– BLM to take into account
a range of physicochemical factors
– More studies appearing on
trophic transfer as a pathway
– Modelling taking into account
ecological, spatial and temporal
aspects of RN distributions
Kumblad et al 2003, 2004
An example of how ecological processes can affect RN uptake:
Daphnia magna 14C assimilation
20
18
3 days of
feeding on 14C
labelled
phytoplankton
DPM/ug Daphnia
16
14
12
10
8
6
4
C
A5
A50
Daphnia take up more C
from irradiated
phytoplankton
A100
B5
B50
B100
Daphnia take up less
C the more they are
irradiated
D5
D50
D100
Intermediate
situation where both
are irradiated?
State of the art: effects
• Wealth of data on single species,
cellular level effects, not so much
of populations, ecosystems
• Problems with extrapolation from
these studies to
population/ecosystem level
• Current attempts to improve the
situation
– More experiments addressing
population-relevant endpoints
– Population models, dynamic
models
– Species Sensitivity Distributions
(SSDs)
+
=
H. Kautsky
An example of how ecological processes can influence effects
of radioactivity:
Indirect effects on interspecies competition
Monoraphidium:Dunaliella ratio relative to
original ratio on Day1
Dunaliella
tertiolecta
vs.
Monoraphidium
contortum
10
9
8
7
6
5
4
3
2
1
0
0
25
50
200
1000
0
2
4
6
8
10
12
Day
2 phytoplankton species, acute gamma up to 1000 Gy at day 0
Reflections on RA2
(from an ecosystem perspective)
• To specify how speciation, cocontaminants, climate conditions
and biological factors influence

radionuclide transfer through
ecosystems in a Nordic context,
and to replace equilibrium
 transfer constants with time and
temperature dependent
functions…
• Uptake in organisms – influence
of environmental factors…great!
• Uptake in organisms - influence of
? biological factors (not so well
developed in the text)
Reflections on RA3
• To identify responses induced in biota
exposed to … radiation … in
combination with other stressors …
under varying temperature/climate
conditions
• Mention of importance of indirect
effects in introduction...though this is
not much expanded
• Field work mentioned briefly,
(...’impacts at individual/ population/
community and ecosystem levels’) but
not expanded on.
• Many single species tests mentioned (of
different trophic levels), but I lack the
link between these.
• Multispecies exposures mentioned - not
many details, careful planning needed!)

?

Reflections on RA4
• To evaluate and improve impact, risk and
benefit-cost assessments … scientifically
based set of decision criteria for handling
radiation and multi-stressors within an
environmental and societal
perspective….ecosystem approach
• Benefit Cost Analysis , Damage Function
Approach…in the last step of DFA - estimate
the economic value of damages from radiation
and multi-stressors, using valuation
techniques for public health and ecosystem
services . If this is achieved it would be a huge
step forward, but unclear how it will be done
• Analyse community-level responses in form of
species sensitivity distributions…  SSDs say
NOTHING about community level responses!!

?!

?!

Challenges
• Complexity!
– Difficult to study
– Difficult to understand
– Even more difficult to implement
in risk assessment etc
• Finding good ways to extrapolate
from simple to complex (or start
looking at the complexity!)
• Finding good ways to reduce
or deal with
– variability
– uncertainty
• Challenging the status quo 
H. Kautsky
GOOD LUCK CERAD!
What about ecosystems?
• Single species are usually
considered.
• Existing methods do not usually
take into account biological and
ecological processes
– these can strongly influence
uptake and exposure to ionising
radionuclides
– indirect effects
MarLin
H. Kautsky
Model ecosystem
experiments
Potamogeton
Ruffe
Smelt
Idotea
Roach (juv)
Fucus
Theodoxus
Zooplankton
Pilayella
Phytoplankton
Particulate
matter
Dissolved
matter
Hydrobia
Cerastoderma Macoma Sediment 0-3cm
Sediment 3-6cm
1.5
MPB1
Mn
Co V Fe
Cl
Ti
As
Ni Al
VP2
Zr
VP1
VP3
Br SED361
PIL1
Th
SED031
Li
PIL3
I
SED033
Cu
SED032
PIL2
Pb
SED362
Mg Si
SED363
FUC3
Cr
FUC1
Rb
FUC2
F
Ba
Cs
THEO4
THEO3
Na
MAC3
MAC1
MAC2
Mo
S
Cd
Nd
C
Zn Ce
Gd Pr
N3 N2
K
N
Yb Sm
N1 G3
Eu
Ho Tb Dy
M2
P
G1
Er Tm Lu
M1 G2
M3
Ca
POM3
POM1
Hg
POM2
Se
-1.5
PC2
MPB2
-1.0
PC1
3.0
Lots of assumptions
Doses to organisms have been estimated in
a rather generalised way, e.g. based on:
– activity concentrations in the
surrounding environment,
– bioconcentration factors, transfer
factors
– reference organisms
– organism geometry
H. Kautsky
Distribution (106 g) and
annual flux (106 g y-1) of C
Next step: adapt C
flow models to
element /
radionuclide flows
with radionuclidespecific data
Kumblad et al 2003/4
• Easy – just measure the
water
• Assume equilbrium (but
this is rarely the case)
• Don’t take into account
biological processes
• Vary widely with time,
space, type of organism,
element...
• Lack of data means
extrapolation necessary
(between types of
organism, elements,
ecosystems...)
Using CRs
Concentration
in water
(mg/L)
x
CR
(mg/kg)/(mg/L)
=
Concentration
in organism
(g/kg)
An example of CR variability: brackish/marine
benthophytes
GM, 90% CI
Nordén et al., 2010 / Konovalenko unpublished
Difficulties with
existing data
• Most data are from
– Individuals
– Single species
– Mortality rather than
reproduction endpoints
– Acute radiation exposure
– High doses
– External irradiation
– Laboratory
– Radiation alone
(and these are the least
relevant!)
+
=
Savannah River Ecology Laboratory
accuracy,
reliability
single
species
experiments
Low Dose-Rate Irradiation Facility
mesocosm
/ model
ecosystem
studies
ecosystem /
field studies
environmental
relevance
H. Kautsky