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Pesticides in urban settings Use of a Pesticide Toxicity Index to evaluate potential toxicity of str

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Title: Pesticides in urban settings Use of a Pesticide Toxicity Index to evaluate potential toxicity of str


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
dont
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
Results Bioassessment index versus urban
intensity
10
Results PTI versus urban intensity indicator
PTI score 10-8
.00000001
11
Results Similar to other urban areas
Source NAWQA summary reports
12
Results Bioassessment versus PTI score
13
Results Temporal variation Kisco R. May
01-Sept 03
14
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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