The movement of pesticide away from the release site in water flowing across the surface is called?

The correct answer is runoff, which refers to the movement of water, along with any substances dissolved within it, across the land surface. When it rains or when water is applied to the soil, any excess water that cannot be absorbed into the ground will flow over the surface, potentially carrying with it pesticides that have been applied in the area. This movement can lead to environmental contamination as the runoff can enter streams, rivers, and other bodies of water, affecting aquatic ecosystems.

In contrast, leaching specifically refers to the process where water moves through the soil profile, dissolving and transporting substances like pesticides into groundwater rather than across the surface. Dilution involves reducing the concentration of a substance by mixing it with a larger volume of water but does not inherently involve movement. Drift describes the airborne movement of pesticides away from the intended target during application, often due to wind, rather than when pesticides move across the surface. Therefore, the definition of runoff aligns perfectly with the description given in the question about the movement of pesticides in surface water.