The vadose zone transmits water and other substances from the surface to the groundwater. Is this an effective filter for all substances?

• A. No, because many times the water follows preferential pathways; because the fluids travel downward by gravity through interconnected pores or as a film on the particle surfaces; because the hydraulic conductivity of the soil is affected by the actions found in the water
• B. Yes, it filters all substances
• C. It filters particulates but not dissolved ions
• D. It is an effective filter for all substances

Answer: (A)