Simulated Mean Annual and Extreme Event Runoff Loads of Herbicides Commonly Used in Urban Areas Throughout the United States
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The runoff of thirty turf herbicides commonly used on lawns, parks, and golf course fairways and greens throughout the United States was simulated using the TurfPQ model. The model was used to obtain ninety nine years of daily water input, water runoff, and herbicide runoff for ten locations: Boston, MA, Charlotte, NC, Denver, CO, Houston, TX, Indianapolis, IN, Jacksonville, FL, Los Angeles, CA, Minneapolis, MN, Portland, OR, and Wichita, KS. Results were summarized as mean annual herbicide runoff loads (g/ha), extreme event herbicide runoff loads corresponding to a 20 year return period (g/ha), mean herbicide runoff as a percentage of annual application, extreme event herbicide runoff as a percentage of annual application, mean annual water input (mm), and mean annual water runoff (mm). Urban areas that produced the highest herbicide runoff loads based on surface runoff were Boston, Charlotte, Houston, Indianapolis, and Jacksonville. Mean annual runoff loads did not surpass 3.4% of the annual herbicide application with most instances considerably less than 1%. Extreme event runoff loads did not surpass 9% of the annual herbicide application but were highly variable and appear to have been very dependent on both location and herbicide. The runoff loads of atrazine, bensulide, DSMA, ethofumesate, napropamide, pendimethalin, and siduron were the largest per hectare. Siduron has the most massive runoff load, which is mainly due to the large amount of the herbicide that is applied annually. Herbicides whose runoff loads contained 3.5% or more of the applied annual amount in one or more simulated event include 2,4-D, atrazine, bentazon, dicamba, ethofumesate, halosulfuron, imazaquin, MCPA, MCPP, quinclorac, siduron, simazine, and triclopyr. These herbicides have the most potential for surface runoff in extreme events. A common factor for these herbicides was low organic carbon partition coefficient values.
pesticide; herbicide; runoff
articledissertation or thesis