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by Karen Riva-Murray, Patrick J. Phillips, Robert W. Bode, and Mark D. Munn

Pesticides in urban settings – Use of a Pesticide Toxicity Index to evaluate potential toxicity of stream water samples to macroinvertebrates. by Karen Riva-Murray, Patrick J. Phillips, Robert W. Bode, and Mark D. Munn. What we know about modern-day pesticides:.

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by Karen Riva-Murray, Patrick J. Phillips, Robert W. Bode, and Mark D. Munn

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  1. Pesticides in urban settings – Use of a Pesticide Toxicity Index to evaluate potential toxicity of stream water samples to macroinvertebrates by Karen Riva-Murray, Patrick J. Phillips, Robert W. Bode, and Mark D. Munn

  2. What we know about modern-day pesticides: • Commonly applied in urban settings • Detected in stream water • Large spatial and temporal variation • Tend to occur as complex mixtures • Have a wide range of toxicities to aquatic organisms

  3. don’t What we ^ know: • Combined toxicity of the entire pesticide mixture • Response of stream biota • Factors affecting potential toxicity

  4. Pesticide Toxicity Index (PTI) Munn, M.D. and Gilliom, R.J., 2001, Pesticide Toxicity Index for freshwater aquatic organisms: U.S. Geological Survey Water-Resources Investigations Report 01-4077, 61 p.

  5. Objectives: • How does PTI vary in relation to urbanization? • What other factors influence PTI in urban settings? • Does change in PTI correspond with change in biological indicators?

  6. PTI Cautions and Caveats : • Use for relative rankings - not actual ‘toxicity’ • Bioassays done on limited taxa • Toxicities not available for all pesticides • Pesticides may not be included in lab analyses • Synergistic effects not accounted for

  7. Study Area – Croton watershed NYC water supply 47 sites small streams range of urban

  8. Methods- Water samples: All sites: Base-flow summer 2000 Kisco R. site: 2-4X/month & storms 2000-03 Macroinvertebrates: Baseflow summer 2000

  9. non-impacted slightly impacted moderately impacted Results – Bioassessment index versus urban intensity

  10. .1 .01 .001 .0001 .00001 .000001 .0000001 People per square mile Results – PTI versus urban intensity indicator PTI score + 10-8 .00000001

  11. Results – Similar to other urban areas Source – NAWQA summary reports

  12. non-impacted slightly impacted moderately impacted Results – Bioassessment versus PTI score

  13. PTI varies with season and with flow Results – Temporal variation; Kisco R. May 01-Sept 03

  14. Pesticide Toxicity Index Pesticide concentrations, April-Sept 2001-03 | 2000 | 2001 | 2002 | 2003 | Results – PTI does not track total concentration

  15. Conclusions: • PTI is a useful tool for evaluating the effects of urbanization on Water Quality • More information is needed • - Toxicities of newer pesticides • - Long-term trends in toxicity • - Synergistic effects • Relative PTI likely to increase with further urbanization • Pesticide toxicity may be an important contributing factor to decline in aquatic biological health in urban streams

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