What environmental factor can enhance the movement of pesticides from soil to water sources?

Heavy rainfall is an environmental factor that can significantly enhance the movement of pesticides from the soil to water sources. When heavy rainfall occurs, it creates saturating conditions in the soil, leading to increased runoff. During this runoff, water can carry away pesticides that have been applied to agricultural fields, gardens, or other treated areas.

Additionally, heavy rainfall can lead to soil erosion, which may further displace pesticides from the soil into nearby streams, rivers, or lakes. The excess water not only facilitates the leaching of pesticides through the soil layers but also causes the pesticides to be washed away directly into water bodies, posing risks to aquatic ecosystems and drinking water sources.

In contrast, high temperatures can increase evaporation and potentially reduce the bioavailability of pesticides in water, drought conditions lead to less water movement, and low humidity typically does not create conditions conducive to runoff or leaching of pesticides.