Which of the following active ingredients is most likely to leach into groundwater?

Tebuthiuron is the active ingredient most likely to leach into groundwater due to its chemical properties and solubility. Tebuthiuron is a systemic herbicide that is soluble in water, which increases its potential to move through the soil profile and into groundwater. Its persistence in soil makes it more likely to remain in the environment and potentially migrate to groundwater sources.

In comparison, glyphosate is typically adsorbed strongly to soil particles and has a lower potential for leaching, which reduces its chances of contaminating groundwater. Similarly, 2,4-D is less soluble in water and has a tendency to bind to soil, making it less likely to leach. Paraquat, on the other hand, is also known for its low mobility due to strong adsorption to soil, which limits its potential to leach into groundwater.

Understanding the properties of these herbicides is crucial for evaluating their environmental impact, especially regarding groundwater contamination.