Iowa Pesticide Applicator Practice Exam

How does solubility affect a pesticide's movement in the environment?

1. Highly soluble pesticides are more likely to remain in the soil

2. Highly soluble pesticides are more likely to move with water in surface runoff

3. Solubility does not affect pesticide movement

4. Less soluble pesticides evaporate faster

The correct answer is: Highly soluble pesticides are more likely to move with water in surface runoff

Highly soluble pesticides have a significant tendency to move with water in surface runoff because they dissolve easily in water. This property allows these pesticides to be carried away from their application site during rain events or irrigation processes. When water moves across soil or surface areas, it can pick up and transport dissolved substances, including highly soluble pesticides, into nearby water bodies, potentially causing contamination. The other aspects of solubility and movement, such as how less soluble pesticides behave, show that they tend to adhere more strongly to soil particles and do not readily dissolve in water. This characteristic keeps them in place longer, making them less mobile, especially during water movement events. Thus, the ability of a pesticide to dissolve impacts its potential for runoff and distribution in the environment, establishing solubility as a crucial factor in understanding pesticide behavior.