Which soil feature elevates the risk of well contamination from herbicides?

Which soil feature elevates the risk of well contamination from herbicides?

• A. Limestone bedrock
• B. Sand
• C. High water table
• D. All of these

Answer: (D)

Groundwater contamination risk from herbicides rises when the soil and subsurface conditions allow more water and dissolved chemicals to move quickly into the aquifer. Sand increases this risk because its coarse texture provides fast, unobstructed pathways for water and offers little surface area for herbicide sorption, so chemicals travel downward with little delay. A high water table reduces the soil layer that contaminants must pass through before reaching groundwater, shortening the travel distance and cutting down on natural attenuation. Limestone bedrock can also raise vulnerability, especially in karst areas, where fractures and conduits create rapid, preferential flow directly to wells, bypassing much of the soil. Because each condition independently increases the likelihood of a herbicide reaching a well, together they make it most accurate to say all of these elevate the risk.

Groundwater contamination risk from herbicides rises when the soil and subsurface conditions allow more water and dissolved chemicals to move quickly into the aquifer. Sand increases this risk because its coarse texture provides fast, unobstructed pathways for water and offers little surface area for herbicide sorption, so chemicals travel downward with little delay. A high water table reduces the soil layer that contaminants must pass through before reaching groundwater, shortening the travel distance and cutting down on natural attenuation. Limestone bedrock can also raise vulnerability, especially in karst areas, where fractures and conduits create rapid, preferential flow directly to wells, bypassing much of the soil. Because each condition independently increases the likelihood of a herbicide reaching a well, together they make it most accurate to say all of these elevate the risk.