What does leaching indicate about a pesticide's properties?

Leaching refers to the process by which pesticides dissolve in water and are washed away from the soil, often moving into groundwater or other bodies of water. This phenomenon primarily indicates that the pesticide has a certain level of solubility in water. Because if a pesticide is leaching, it means that it is able to move freely through the soil with water, which would not occur if the pesticide were not soluble.

Therefore, the correct understanding of leaching supports the property that a pesticide must be soluble in water. It can also imply something about the pesticide's behavior in the environment, including persistence, but leaching itself does not directly indicate persistence. Persistence in soil means that the pesticide remains active for long periods without breaking down, which is separate from the process of leaching.

This context clarifies why the focus on solubility is crucial in understanding the leaching process. Pesticides that can leach are effectively mobile and can potentially contaminate water sources, impacting environmental health.