Pesticide Detections in Wash Off from Residential Hardscapes

Transcription

1 Pesticide Detections in Wash Off from Residential Hardscapes Darren Haver*, UC Cooperative Extension Orange Tamara Majcherek, UC Davis, Plant Sciences Jay Gan and Sveta Bondarenko, UC Riverside, Environmental Sciences

2 Residential Pesticide Applications Introduction Perimeter sprays around buildings Spot treatments Applications directly on plant material Crack and crevice

3 Introduction continued - Impervious surfaces Driveways, walkways, and patios connected Downspouts and Drains Delivers storm water away from foundation Landscape drainage pipes carries water to gutter

4 Introduction continued - Pesticide Movement Rain Irrigation Car washing Cleaning hardscape

5 Introduction continued - Hardscape Wash Off Approximately 5 gallons of water per minute to wash driveways and sidewalks Higher pressure stream of water compared to sprinkler output Mobilizes more debris (leaves, sediment, dust, etc )

6 Questions Will washing off a hardscape result in a significant source of pesticides reaching the gutter? How long after the application of a pesticide can it be detected in wash water? Do landscapes designed to minimize runoff reduce pesticide loading to storm drains?

7 UC ANR South Coast Research and Extension Center Study Site

8 Landscape A Typical Hardscape

9 Landscape A Typical Hardscape

10 Landscape B Low Impact Design I Hardscape

11 Landscape B Low Impact Design I Hardscape

12 Landscape C Low Impact Design II Hardscape

13 Landscape C Low Impact Design II Hardscape

14 Pre-Treatment Wash Methods Background levels of pesticides (previous studies) Perimeter Pesticide Treatment 1 foot out, 1 foot up fan spray around perimeter using fipronil at a rate of.06% (0.96 g fipronil applied to each landscape). Lawn and Garden Treatment Spray applied to each landscape using 0.3% bifenthrin from a RTU hose-end product or (0.94 g bifenthrin applied to each landscape) Hardscapes washed off at defined intervals following pesticide application.

15 Applied Water To Stimulate Runoff Landscape Day 7 Week 1 Day 14 Week 2 Day 21 Week 3 Day 28 Week 4 Day 56 Week 8 A 28 gallons 38 gallons 35 gallons 30 gallons 32 gallons B 30 gallons 38 gallons 38 gallons 30 gallons 32 gallons C 40 gallons 42 gallons 40 gallons 38 gallons 32 gallons

16 Pre-Treatment Baseline Pesticide Concentrations in Runoff

17 Bifenthrin in Wash Water

18 Bifenthrin in Wash Water

19 Bifenthrin Loading from Hardscape Washing Nanograms of bifenthrin Typical (13.8%) LID I LID II (4%) (3.4%) 56 d 28 d 21 d 14 d 7 d 24 h

20 Fipronil in Wash Water

21 Fipronil in Wash Water

22 Fipronil Loading from Hardscape Washing Nanograms of fipronil d 28 d 21 d 14 d 7 d 24 h 0.0 Typical (1.6%) LID I (.3%) LID II (.19%)

23 The Metabolite Issue Fipronil Anaerobic conditions: sulfide Aerobic conditions: sulfone Photochemical: desulfinyl Metabolites are more toxic than fipronil 23

24 Fipronil Breakdown Products Fipronil sulfide was not detected in any samples. Fipronil desulfinyl was not detected in the 24 h samples Low concentrations were detected in wash off from all three landscapes (7 day to 56 d) Fipronil sulfone was detected a very low concentrations in samples taken at all intervals from all three landscapes.

25 Conclusions Washing off landscape hardscapes resulted in pesticide loss during the intervals analyzed. A significant loss of bifenthrin occurred from the 24 h washoff from the typical landscape. Irrigation over spray would also contribute to the loss of material. Location of landscape drains and connected hardscape contributed to runoff. Fipronil loss even in the typical landscape was less than expected.

26 Conclusions continued Adjustments to the landscape design reduced the overall pesticide load reaching the gutter. Relocating or covering hardscape drains. Redirecting runoff from hardscapes through improved infiltration or towards vegetation.

27 Future Research Determine if a delay in washing off (7 days or 14 days) following treatment would significantly reduce the mobilization of pesticide. Analyze all runoff events (wash off and irrigation) in order to calculate the total loss of material over a specific time period. Investigate the use of simple mitigation strategies such as covering drains during application, utilizing a pin stream spray technique, and buffer areas.

28 Thank You County of Orange Watershed and Coastal Resources California Department of Pesticide Regulation Drs. Michael Rust and Les Greenberg, UCR Entomology Drs. Jay Gan and Sveta Bondarenko, UCR Environmental Sciences Tammy Majcherek, UC Davis Plant Sciences UC ANR South Coast Research & Extension Center