What property of a pesticide would make it more likely to move in surface water runoff?

A pesticide's solubility in water significantly influences its potential for movement in surface water runoff. High solubility means that the pesticide can easily dissolve in water, increasing the likelihood that it will be carried away with surface runoff during rain or irrigation events. When heavy rains occur, pesticides that are highly soluble can be transported from the treated area into nearby streams, rivers, and lakes, posing risks to aquatic ecosystems and water quality.

In contrast, high volatility refers to a pesticide’s tendency to evaporate into the atmosphere, which does not directly relate to surface water movement. Low toxicity is relevant for safety and environmental impact assessments but does not influence the physical behavior of the pesticide in water. Low density may suggest that the pesticide could float or become suspended in water, but this is not a primary factor in its movement with surface runoff like high solubility. Thus, high solubility is a key property that governs the likelihood of a pesticide's movement through surface water runoff.