Processes controlling the fate of pesticides in the environment

Authors: Lerch, Robert

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/26/2018
Publication Date: 2/11/2019
Citation: Lerch, R.N. 2019. Processes controlling the fate of pesticides in the environment [abstract]. Weed Science Society of America Meeting, February 11-14, 2019, New Orleans, Louisiana. Paper No. 470.

Interpretive Summary:

Technical Abstract: Responsible use and management of pesticides requires a detailed understanding of the numerous processes that determine their environmental fate. This presentation will cover the major fate pathways, including soil degradation and sorption, volatilization, photolysis, and hydrologic transport, and it will provide some perspective on the key environmental compartments impacted by pesticides. Further, the critical role that plants can play in effecting pesticide fate in direct and indirect ways will be examined. For example, members of the Poaceae family produce allelopathic compounds (benzoxazinoids) that can directly react with s-triazine herbicides in soil. Plants also have a major effect on soil quality leading to increased soil microbial activity and pesticide sorption. Although off-site transport processes typically account for <10% of applied pesticide mass, this is sufficient to cause impairment of ecosystems and human health. Thus, another focus will be the factors affecting hydrologic transport and the impact of pesticides on water quality. Water quality data will be presented demonstrating the overarching importance of soil properties on watershed vulnerability to pesticide transport. By synthesizing our knowledge of degradation and transport processes, pesticide risk assessment models can be developed to predict areas within watersheds that are most vulnerable to contamination of water and air resources. An example of a pesticide risk model will be presented as one approach to targeting conservation practices to the most vulnerable areas. Lastly, a brief overview of management practices that effectively reduce off-site transport will be reviewed, with an emphasis on the environmental trade-offs associated with these practices.