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

• A. Runoff & erosion are sources of surface water contamination by pesticides.
• B. Drift is seldom, an issue with indoor applications.
• C. Leaching is the main way that pesticides travel in great distances.
• D. Evaporation is the primary means of long-range transport.

Answer: (A)

Movement of pesticides from where they’re applied to water bodies happens mainly through water-related pathways. Runoff and erosion are the key processes: during rain or irrigation, pesticides can be dissolved in water on the soil surface or attached to eroding soil particles and be carried into nearby streams, rivers, and lakes. Sediment-bound pesticides that ride along with eroded soil also end up contaminating surface water. This is the most direct and common route for surface water contamination after application.

Drift involves movement of spray by air and is a bigger concern outdoors where wind can transport droplets away from the target area; indoors, drift is less of an issue, so describing it as rarely a problem with indoor applications isn’t the best generalization. Leaching moves pesticides down through the soil toward groundwater rather than directly contaminating surface water over long distances, so it’s not the main pathway for surface water spread. Evaporation or volatilization can move some pesticides into the air, but it’s not the primary means by which pesticides travel long distances to surface water.