Certified Crop Advisor Practice Exam

Which of the following pesticide characteristics is expected to lead to the most ground water pollution?

1. High volatility

2. Little absorption by colloids

3. Strong adsorption to soil

4. Low solubility

The correct answer is: Little absorption by colloids

The characteristic that is most likely to lead to ground water pollution is little absorption by colloids. When pesticides have low affinity for colloidal particles in the soil, they tend to remain in the soil solution and can easily leach down through the soil profile. This movement can result in the contamination of ground water as the chemicals migrate downward. Colloids are small particles in the soil that can adsorb or attract chemical substances. If a pesticide does not strongly absorb to these particles, it is more prone to being dissolved in water and transported through soil layers, ultimately reaching groundwater sources. This characteristic directly relates to the potential for groundwater contamination because it affects the pesticide's mobility in the environment. In contrast, characteristics such as high volatility or strong adsorption to soil typically reduce the likelihood of pollutants reaching groundwater. High volatility leads to more pesticide vaporization, while strong adsorption means that pesticides adhere more closely to the soil particles and are less likely to leach into the water. Low solubility, although it may suggest reduced mobility, does not impact the leaching potential as significantly as low absorption by colloids does.