1. How to protect groundwater organisms to toxic substances?
Wilko Verweij (RIVM)
Brigitte Blonk (RIVM/UvA)
Michiel Kraak (UvA)
EU Working Group Groundwater, Luxembourg,
5 October 2015

2. Contents Groundwater organisms
Sensitivity of groundwater organisms to toxic substances
Options for protecting groundwater organisms in WFD
Conclusions

3. Groundwater organisms
There is more life in groundwater than you can see:
viruses
fungi
bacteria
invertebrates
Many species known (at least 7000)
Invertebrates adapted to special conditions
often blind
translucent
low metabolic rate
slow reproduction

4. Groundwater organisms
Distribution of invertebrates in the Netherlands
Occur where coarse sediments
are found
International context: caves!
salamanders
snails
fish

5. Objectives of Water Framework Directive
WFD: no objectives to protect groundwater organisms
But recital of Groundwater Directive (2006):
Research should be conducted in order to provide better criteria for ensuring groundwater ecosystem quality and protection.
Where necessary, the findings obtained should be taken into account when implementing or revising this Directive.
Such research, as well as dissemination of knowledge, experience and research findings, needs to be encouraged and funded.
We now know:
that organisms occur in groundwater
Groundwater Directive acknowledges their importance
that these organisms are not currently protected by Water Framework Directive (including Groundwater Directive)

6. How to protect groundwater organisms?
Are groundwater organisms equally sensitive to toxic substances as surface water organisms?
What we did:
retrieve data about toxicitity of substances to surface water organisms
collect data for groundwater organisms
compare
focus on invertebrates
Method: Species Sensitivity Distribution

7. Species Sensitivity Distribution
Collect toxicity data for one substance for as many species as possible
Then sort
Species 1: LC50 = 12 µg/L
Species 2: LC50 = 2222 µg/L
Species 3: LC50 = 5 µg/L
Species 4: LC50 = 144 µg/L
Least sensitive organisms
Plot toxicity data for surface water organisms together with toxicity data for groundwater organisms in one graph and compare…
Most sensitive organisms

8. Results Literature scan and interviews with experts
Toxicity data for groundwater organisms rather scarce
Data available for
6 pesticides: 3,4-dichlorophenol, aldicarb, chlorpyrifos, pentachlorophenol, permethrin, thiram
1 other organic compound: toluene
2 nutrients: ammonium, potassium nitrate
6 metal(loid)s: arsenic, cadmium, chromium, copper, lead, zinc
3 inorganic Cl-compounds: chloride, hypochlorite, chlorine
So 18 compounds in total: not many, but rather a wide range
Only data from acute toxicity tests available

9. Results
For pentachlorophenol, data for one groundwater species were found
Five experiments were performed
In one experiment, toxicity
is below 5% cut-off

10. Results For ammonium, data for three groundwater species were found
For one of them, toxicity is around 5% cut-off

11. Results For all other 16 substances, no data below 5% cut-off occur
Some data points also in high range
E.g. zinc: more or less equally distributed

12. Summary of results + WFD-instrument
For the substances for which data are available:
Sensitivity of groundwater organisms more or less similar to that of surface water organisms
If surface water standards would be applied to groundwater, groundwater organisms are protected from acute effects
Threshold values can be key instrument to implement protection of groundwater organisms in WFD

13. Threshold values: What do WFD/GWD require?
Threshold values should be based on
human use
groundwater dependent ecosystems
Only when relevant for the groundwater body
So: if groundwater body influences surface water, one should take into account surface water standards
Processes like adsorption or dilution may be taken into account  threshold values can be higher than surface water standards

14. Solution...
If:
we use surface water standards as groundwater threshold values, even when no groundwater dependent ecosystems are present for a GWB
we do not apply adsorption / dilution etc.
we can protect groundwater organisms

15. Conclusions
Groundwater organisms are not protected under current EU-legislation
There are indications that groundwater invertebrates are equally sensitive to toxicants as surface water organisms, but this is based on limited data
Therefore research focusing on other groups of organisms and on chronic effects is needed
By applying surface water standards to groundwater (as threshold values), groundwater organisms can be protected, but only fromacute toxicity

16. From Guidance Document...