Which practice would help prevent groundwater or surface water contamination?

• A. Select pesticides that tightly adsorb to soil and are not persistent
• B. Use pesticides with high volatility
• C. Apply pesticides near water sources during rain
• D. Do not wash application equipment

Answer: (A)

The key idea is how a pesticide’s behavior in the environment affects its potential to reach water. Pesticides that bind tightly to soil stay attached to soil particles, making it much less likely for them to be washed away by rain or percolating water into groundwater. If the chemical also degrades quickly (is not persistent), there will be fewer residual molecules remaining to migrate to water bodies. Together, strong soil adsorption and rapid degradation keep the pesticide at the application site and reduce contamination risk for both groundwater and surface water.

By contrast, products that are highly volatile can drift away through the air, and applying near water sources during rain increases the chance of runoff and leaching. Not washing application equipment can leave residues that might contaminate water if wash water isn’t collected and treated properly.