1. SIRLE TRESTIP University of Tartu Cagliari 2011
Presentation for 14th European Seminar on Geography of Water REMOVAL OF PESTICIDES IN TREATMENT MICROCOSM WETLANDS: HEXACHLOROBENZENE EXAMPLE
SIRLE TRESTIP
University of Tartu
Cagliari 2011

2. Table of contents Wetlands Constructed Wetlands Pesticides
Hexachlorobenzene example
Aim of the work
Materials and methods
Results and discussion
Conclusion

3. Wetlands
One of the most biological productive ecosystems on the planet
An area of land that is seasonally or permanently waterlogged 

4. Constructed Wetlands Cheap to operate and maintain
Remove effectively contaminants without the addition of expensive chemicals or extra energy requirements. 
Aesthetically pleasing
Can provide habitat for many aquatic and terrestrial species
Designed to mimic natural wetlands, but optimize the biological and physical properties in order to maximize efficiency. 

5. Pesticides Group of artificially synthesized substances
Used for enhancing agricultural production
Insecticides, herbicides, fungicides
European soil – 320,000 tons per year
France, Italy, Germany, Spain, Portugal – 80% of pesticides in Europe

6. Hexachlorobenzene (HCB)
One of 12th banned POPs
Used mostly as a fungicide
Highly volatile and very persistent in environnment
High toxity and potentiality to accumulate through food chain
Found all over the world: air, soil, sediments, water, biota, human tissues
Still used as an intemrediate in some countries

7. HCB example: aim of the work
To study the effect of removal of HCB from treatment microcosm
To clarify the impact of different macrophytes (Typha and Phragmites) on different concentration of HCB (high-HCB and low-HCB) in microcosm wetland
To analyze the effects of some environmental factors on HCB biodegradation (like temperature, pH, TN, DOC, etc.)

8. Material and Methods Plant rhizomes collected in February 2011
Two different plant species (Typha and Phragmites)
Selected strongest plants (9+9)
Two different concentrations: high – 300 mg/kg and low – 15 mg/kg
Together with control 8 parallel testings
Taking 5 times water samples and 3 times soil samples
Weekly measurements of water parameters

9. Wetland microcosm Gravel (40 cm) Mesh Contaminated soil (180 cm)
Water (70 cm)
Plant in the middle

10. Results and Discussion Environmental parameters
No reliable similarity between water parameters and presence or absence of plants
pH increase from 7.4 to 7.9 at the end of the experiment
Temperature increase from 17°C to 19°C at the end of the experient

11. Results and Discussion HCB concentration in water
High-HCB: dramatic decrease after four weeks
At the end of the experiment only 16% - 26% remained from the initial concentration
Low-HCB: HCB concentration decreased, in the end of the experiment 14% - 38% from the initial.

12. Results and Discussion HCB concentration in soil
No lag-phase
Most of the HCB was removed in first two weeks
Low-HCB control increasing – mistake of sampling??
At the end of the experiment the average remained HCB concentration 2% from the initial.

13. Results and Discussion Plant biomass
Typha grew better than Phragmites, but Phragmites was weaker already in the beginnig of the experiment
In the end of the experiment new Typha shoots
Plants suffered under stress: plant grow was limited also in treatments without HCB
Stress was probably caused due to drastic environmental change

14. IN THE MIDDLE
IN THE END

15. Further study and recomendations
New outdoor experiment mimicing realistic manipulations of constructed wetland
Mesocosms instead of microcosms
Wetland soil and more plant species
HCB concentration in plants (above-ground and belowe-ground)
To identify the microbial communities (real-time PCR)
Start sampling in earlier stage for finding out lag-phase.

16. Conclusion
Wetland microcosms were effective in removal of HCB: from soil ~ 90% and from water 70% of initial concentrations were removed.
Plants played role in removal of HCB
There was no significant difference between plant species to the removal of HCB

17. THANK YOU FOR LISTENING!
QUESTIONS?