1. New integrated tools for risk assessment and decision making on a basin scale
Jos van Gils, Elena Semenzin, Muriel Gevrey, Peter Von der Ohe,
Bert van Hattum, Dick de Zwart, and …

2. Introduction
Ecological status is threatened by different pressures (“multiple stress”, Segner)
Among them toxic stress which to some degree covered by insufficient chemical status, however
incomplete data sets for priority substances
emerging pollutants
mixture toxicity
(reduced) bio-availability
bio-accumulation

3. MODELKEY approach
Weight of Evidence (WoE) approach to assess the risk of chemicals to the Good Ecological Status, based on different Lines of Evidence (LoE):
Chemistry
Biology
Toxicology
(also in DSS, Gottardo)
pragmatic way to deal with
conceptual uncertainties

4. stress can be differentiated for different groups
Predicting toxic stress: Toxic units Ci
LC50i
Toxicity indicator: Toxic Units =
with
Ci = concentration of chemical i
LC50i = lethal concentration (48h) of chemical i, for Invertebrates, Algae and Fish
micro-algae (Selenastrum capricornutum)
invertebrates (Daphnia magna)
fish (Pimephales promelas)
stress can be differentiated for different groups

5. Predicting toxic stress: msPAF
PAF: potentially affected fraction (of species)
msPAF: multi-substance PAF (mixture toxicity)
Risk
Assessment ò
PAF
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1 - 3 2 4 5
Cumulaitve
probability
Log Concentration ( m
g/L)
EQC ð HC
L(E)C 50
or NOEC
SSD
bio-availability!
Posthuma, L., Suter, G. W., II, and Traas, T. P., editors Species Sensitivity Distributions in Ecotoxicology. Lewis Publishers, Boca Raton, FL, USA.

6. Observing effects: SPEAR indicator
The SPEAR indicator (SPecies At Risk), species are classificied based on
high physiological sensitivity (based on acute LC50)
long generation time, low reproductivity
reference community
at risk
not at risk
 SPEAR ~ 50%

7. Ecological status – SPEAR
indicator
Ecological status

8. Predicted effects are observed ( Llobregat)10 20 30 40 50 60 70 80
SPEAR [%]
n = 30 - - 4 - - 3 3 - - 2 2 - - 1 1
Predicted toxic pressure
Toxic Units
Daphnia magna
* Von der Ohe et al Towards an Integrated Assessment of the Ecological and Chemical Status of European River Basins. IEAM 5,

9. but large uncertainty, variability
Predicted effects are observed ( Scheldt)
msPAF predicted loss of species, based on LC50 values, is significantly related to the actually observed
loss of species
but large uncertainty, variability

10. Predicted stress confirmed in bio-assays
Effect
Predicted toxic pressure

11. MODELKEY approach
Schmitt-Jansen

12. Cost-effective measures
Prioritisation of sites/sources/chemicals
tools in DSS (Gottardo)
exposure model

13. Exposure modelling EXPOBASIN model:
River & Basin Geometry
River Hydrology & Hydraulics
Fine sediment dynamics
Transport and fate of chemicals
Bio-availability and -accumulation
Exposure, risk indicators
Environmental conditions
EXPOBASIN model:
spatial relations between causes (pollution sources) and downstream effects (ecological risk)
for quantitative and objective ranking of chemicals and/or pollution sources
(including sediments and biota)
easy application to all European river basins

14. Exposure modelling source A source B “local” impact “exported” impact
based on TU as a risk indicator

15. Next steps towards cost-effective programmes of measures:
systems analysis for selected chemicals,
integrated source-oriented and effect-oriented approaches,
integration of compartments water, air, soils, ground water
enhanced multi-stressor assessments
stressor-specific indicators
… (Segner)
exploring/enhancing “emerging” Europe-wide harmonised databases

16. Thank you for your attention!