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Ambient ozone and crop loss: establishing a cause-effect relationship
S V Krupa1, M Nosal, A H Legge
1Department of Plant Pathology, University of Minnesota, St. Paul, Minnesota 55108, USA.
Environmental Pollution (Barking, Essex : 1987)
|January 1, 1994
Summary
Ozone (O3) exposure significantly reduces crop yields, particularly when concentrations range from 50 to 87 ppb. Analysis of open-top chamber data reveals a critical threshold for O3 impact on vegetation, informing potential air quality standards.
Area of Science:
- Environmental Science
- Agricultural Science
- Atmospheric Chemistry
Background:
- Open-top chambers are used to study the effects of air pollutants on crops.
- Previous research has indicated potential negative impacts of ozone on crop yields.
- The National Crop Loss Assessment Network (NCLAN) collected extensive data on crop responses to environmental conditions.
Purpose of the Study:
- To analyze the US NCLAN open-top chamber data retrospectively.
- To determine the relationship between ambient ozone (O3) concentrations and crop yield reductions.
- To identify critical ozone exposure levels that impact vegetation.
Main Methods:
- Retrospective mathematical analysis of NCLAN open-top chamber data.
- Comparison of crop yields between non-filtered (NF) and charcoal-filtered (CF) chambers, and ambient air (AA) treatments.
- Statistical analysis, including univariate linear regressions, of O3 frequency distributions and per cent yield losses.
Main Results:
- 77% of examined crop harvests showed no significant yield difference between NF and AA treatments.
- Seven cases exhibited statistically significant yield reductions in NF compared to CF treatments.
- A clear separation in O3 frequency distributions was observed for cases with yield loss versus no yield loss at concentrations above 49 ppb.
- Cumulative O3 concentrations between 50 and 87 ppb were the best predictors of yield loss (adjusted R2 = 0.712, p = 0.011).
Conclusions:
- Ambient ozone concentrations between 50 and 87 ppb are critical for predicting crop yield reductions.
- The frequency of occurrence of hourly O3 concentrations within this range is a key factor.
- These findings can inform the development of meaningful ambient O3 standards for vegetation protection.