MDARD Michigan Core Pesticide Applicator Practice Exam

Pesticides can reach surface water from various sources. Which of the following is NOT one of these sources?

1. Drift

2. Retention in soil

3. Rainfall

4. Groundwater discharge

The correct answer is: Retention in soil

Retention in soil is not a source through which pesticides can reach surface water. Instead, it refers to the ability of soil to hold pesticide chemicals in place, reducing their movement into water bodies. When pesticides are applied to land, they may bind to the soil particles and remain in the soil for various lengths of time before degrading or being taken up by plants. This retention reduces the likelihood of those pesticides entering surface waters directly. In contrast, drift, rainfall, and groundwater discharge all have direct pathways for pesticide movement to surface water. Drift occurs when pesticides are carried away from the target site by wind during or after application. Rainfall can wash pesticides off surfaces and facilitate their movement into nearby streams and lakes. Groundwater discharge involves groundwater carrying dissolved pesticides into surface water bodies when the groundwater emerges at the surface. Understanding these pathways helps in recognizing how pesticide applications can influence water quality and the environment, emphasizing the importance of proper application techniques and timing to mitigate these risks.