Pesticides in Danish streams and lakes: Concentrations, loss and ecological effects

1. Pesticides in Danish streams and lakes: Concentrations, loss and ecological effects Brian Kronvang, NERI BKR@DMU.DK

2. Introduction • 2.841.000 kg active ingredients was applied in Danish agriculture during the year 2000 • Following spraying pesticides can reach surface water due to wind drift, leaching, runoff and bad handling • Our knowledge about the presence of pesticides in surface waters have been very limited

3. Pesticide pathways to streams

4. NOVA-2003 • Analysed for 68 pesticides i 5 larger streams and 48 pesticides i 25 small streams in agricultural catchments during 2000 og 2001 • In total measured 43 pesticides and metabolites above the detection limit • Detection limit normally 0.001 ug/l

5. Pesticide detection frequencies and maximum concentrations measured in streams in the Danish Aquatic Monitoring Programme 2000

6. Is there any ecological effects of pesticides in streams? Fyns amt (2002)

7. Lakes and ponds

8. NOVA-2003 • Measured for 48 pesticides in 8 lakes in 2001 • In total measured 42 pesticides or metabolites • Maximum concentration was 0,22 µg/l (diuron) • Maximum median concentration was 0,03 µg/l

9. Maximum concentrations in NOVA streams and lakes

10. Concentrations of pesticides in 69 lakes and 47 ponds sampled in regional programs

11. Intensive study in 2 catchments

12. Study catchments

13. Lillebæk (culverted sub-catchment) Water 104 Suspended sediment 8 Streambed sediment 6 Lillebæk (entire catchment) Water 96 Suspended sediment 8 Streambed sediment 6 Odderbæk Water 68 Suspended sediment 10 Streambed sediment 6 Number of samples taken in the two catchments during 1999-2001

14. Pesticides in Stream Water

15. Pesticides in Suspended Sediment

16. Applied amount of pesticides in the 3 catchments and the detection frequency and concentration levels in streams

17. Terbuthylazine in Lillebæk, Funen

19. Pesticide application, loss and loss ratios18 different pesticides during 2000 ____________________________________________________ Applied Loss Loss ratio (kg a.i.) (gram) (%) ____________________________________________________ Odderbæk 634.32 9.75 0.00154 Lillebæk 119.45 12.51 0.0105 (culverted sub-catchment) Lillebæk 66.29 5.30 0.00800 (Open sub-catchment ____________________________________________________

20. Transport/applications

21. Loss

22. Breakthrough curve for the Herbicide Bentazone

23. Breakthrough curve for the Insecticide Dimethoate

24. Possible Ecological Effects

25. Gammarus survival • Caves installed 10 m upstream, at the tile drain outlet and 10 m downstream • 6 caves each with 10 Gammarus • The experiment prevailed for 8 hours only • Mortality and inactivity

26. Effects – Drain experiment

27. Conclusions • Under “normal” conditions the concentration of pesticides are generally low in Danish streams and lakes • During storm events short lived high and ecological critical concentrations can occur • The highest concentrations are detected in small streams and ponds • Effects have been documented on the macroinvertebrate Gammarus pulex during an experiment