Oklahoma Service Technician Practice Exam

Which condition promotes the rapid movement of pesticides into groundwater?

1. Fine-textured soil with high organic matter

2. Coarse, sandy soil

3. Clay soil with low permeability

4. Moist soil with dense vegetation

The correct answer is: Coarse, sandy soil

The condition that promotes the rapid movement of pesticides into groundwater involves coarse, sandy soil, which is characterized by larger particles that create more significant void spaces between them. This structure allows water, along with any dissolved substances such as pesticides, to percolate through the soil more quickly. In sandy soils, the lower capacity to hold onto moisture means that water can move downward rapidly, especially during rainfall or irrigation events. Pesticides applied to the surface can quickly reach the groundwater beneath because there are fewer physical or chemical interactions that would otherwise slow down their movement. In contrast, fine-textured soils with high organic matter can retain water and pesticides more effectively, slowing their movement. Clay soils, due to their low permeability, are also less conducive to rapid movement into groundwater. Moist soil with dense vegetation typically enhances pesticide uptake by plants and reduces runoff, further preventing contaminants from reaching groundwater quickly. Thus, the sandy soil condition distinctly poses a higher risk for the rapid infiltration of pesticides into the groundwater system.