1. Jasperien de Weert Foppe Smedes (Recetox, Brno)
Application of passive sampling for monitoring pesticides and pharmaceuticals in groundwater.
Jasperien de Weert
Foppe Smedes (Recetox, Brno)
12 april 2016

2. Introduction: conventional monitoring
Conventional monitoring occurs by pumping groundwater
Easy and the sampled volume is well defined
However, this method
- Can result in disturbing the groundwater zones
Gives a “snap shot” concentration
The sampled volume is limited which often gives analytical results below limits of detection
12 april 2016

3. Alternative: passive sampling
- Use of a sampler existing of sorption material is placed in the well.
- Transport of compounds from water to sampler by diffusion
Benefit
- Sampler can be deployed for a long time period (weeks/months)
Larger sampled volume  lower concentrations
- Average concentration over sampling period
- Different types of passive samplers
* Equilibrium samplers; like silicone rubber, LPDE, PBDS
* Adsorption samplers: like Cermic dosimeter, Empore disk
Disadvantage
Not for all samplers, the calculation of final water concentrations is well defined
12 april 2016

4. Application
- Technique is used for monitoring e.g. volatile compounds like VOCl’s and BTEX in ground water at polluted sites, in several European countries, like France and Germany - For surface water monitoring for e.g. pesticides, passive sampling is already more frequently used in the Netherlands, for groundwater not used
12 april 2016

5. Our study: Test passive sampling and monitoring pesticides and pharmaceuticals in Noord-Brabant
Aim:
1) Test application of passive sampling in
groundwater wells to detect compounds in earlier
stage
2) Monitor on pesticides and pharmaceuticals
Locations
- Two locations of monitoring network
Province of Noord-Brabant
- Agricultural area
- Pesticides detected in the past
- Wells with filters on ca. 4 m-mv and ca. 22 m-mv
12 april 2016

6. Field work
Application of two type of samplers (silicone rubber and Empore disks)
Comparison with conventional taken water samples
Two sampling periods
Deployment for 6 to 7 weeks
Analysis of mainly hydrophilic pesticides and pharmaceuticals
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7. Results: detected compounds
Most compounds detected by Empore disk  hydrophilic sampler
Less compounds on silicone rubber  hydrophobic sampler
Compounds found in conventional water samples also found on samplers
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8. Results: pharmaceuticals
Four pharmaceuticals (salcilyc acid, sulfamethazine, iohexol and fluopicolide) were detected in both periods, in water and/or on samplers
Paracetamol was found only on the samplers
12 april 2016

9. Results: pesticides Less added value for “usual suspects”:
- Compounds like, bentazon and diuron and simazine 
concentrations far above the limits of detection in water and on samplers
Differences in concentration of these well analyzed compounds in water and on samplers was maximum a factor of 3
Some was uptake (or extraction) by samplers not optimal resulting in lower concentrations compared to water samples  needs further optimization
Added value for “other” pesticides:
Sixteen of analyzed pesticides were only measured on samplers and not in the water samples and in regular monitoring
The pesticides found only on samplers were detected in amounts well above the LOQ resulting in concentrations in the 1 to 10 ng/l range
This were compounds like iprodion, terbuthylazin-desethyl, oxamyl and fenoxycarb.
12 april 2016

10. Conclusions/remarks
Samplers easy and well applicable for monitoring pesticides in groundwater. Pharmaceuticals need further testing.
Added value in trend watching (“early warning”) because of detection in low concentrations
Application of passive sampling can refine the watch list
Clear guidelines and more possibilities in policy can help to use these techniques in the monitoring
12 april 2016

11. Thank you for your attention Questions?
12 april 2016