What is a true statement about the movement of pesticides from the application site?

The correct statement regarding the movement of pesticides from the application site is that runoff and erosion are sources of surface water contamination by pesticides. When pesticides are applied to agricultural fields or other areas, various environmental factors can influence their movement. Rainfall, especially heavy rainfall, can lead to runoff, which is the process where water flows over the surface of the ground and can carry chemicals, including pesticides, into nearby water bodies. Erosion, which involves the removal of topsoil, can also transport these substances along with soil particles, ultimately leading to contamination of surface waters.

Contrary to the other statements, pesticide movement is not limited to heavy rainfall; even light rain can contribute to runoff. Additionally, pesticides can indeed move through soil and may not always remain bound to the application site due to factors such as soil texture, moisture, and chemical properties of the pesticides. Thus, the statement about runoff and erosion accurately reflects the complexities of pesticide behavior in the environment.