What is a significant pathway for surface water contamination by pesticides?

Runoff is a significant pathway for surface water contamination by pesticides because it occurs when precipitation or irrigation causes excess water to flow across the ground surface. As this water moves, it can pick up pesticides that have been applied to agricultural fields or lawns and transport them into nearby streams, rivers, and lakes. Factors such as slope, soil type, vegetation cover, and rainfall intensity can influence the amount of runoff that occurs and how much pesticide is carried away.

In contrast, while evaporation may lead to pesticide loss to the atmosphere, it does not contribute directly to water contamination. Soil erosion can also facilitate the movement of pesticides but is typically less direct than runoff and more dependent on the type of soil and vegetation. Soil absorption relates to how pesticides are taken up by soil particles, which can reduce the availability of these chemicals for runoff, thereby preventing contamination of surface water.