Correlating Agricultural Use with Ambient Concentration of 1,3-Dichloropropene During the Period of 2011-2014
Abstract
1,3-Dichloropropene, also known as 1,3-D or Telone, is a widely used fumigant in California agriculture, used primarily for its nematicidal properties. The Department of Pesticide Regulation’s (DPR) Air Monitoring Network (AMN) collected a 24-hour sample each week to measure airborne concentrations of 1,3-D in three California communities during the period of 2011-2014. DPR concurrently collected pesticide use reports (PURs) from pesticide applicators, which provide details on application location, timing, and amount of 1,3-D applied. Use data was analyzed for its relation to 24-hour concentration data in a regression framework. We tested several spatial and temporal scales f rom which to select use data for inclusion in the final regression. Adjustment factors were used as an indirect method of accounting for application practices and their effect on emissions.
We found evidence of a positive relationship between 1,3-D use within 5 miles of a monitoring site and 24-hour ambient 1,3-D concentration, but the linear regression explained only a small (25%) proportion of the overall variation in concentration data. The large proportion of unexplained variation suggests that the resulting regression is not of practical use for estimation of 24-hour ambient concentrations. A relatively high number of detections with no associated use within a timespan of a week prior to sampling may suggest influence from applications outside the spatial and temporal scales examined in this study. Environmental factors such as meteorology and topography may have contributed some of the unexplained variability in the regression. Additional possible sources of error are discussed.