Final answer:
DNAPLs travel down until they hit an aquitard. They adhere to soil particles rather than dissolving in groundwater or floating on the water table. The movement of such pollutants is complex and often modeled to predict their environmental impact.
Step-by-step explanation:
DNAPLs (Dense Non-Aqueous Phase Liquids) are a class of pollutants that are heavier than water and have a low solubility in water. These substances tend to adhere to soil particles due to adsorption and travel down until they hit an aquitard, which is an impermeable layer that prevents further downward movement. They do not dissolve easily into the groundwater due to their low solubility, and they don't float on the water table because they are denser than water. Thus, the correct answer from the options provided is (b) DNAPLs travel down until they hit an aquitard.
The transport of pollutants such as DNAPLs through the soil and into groundwater systems is a complex process that involves various mechanisms like diffusion, adsorption, and precipitation. These processes are often modeled using hydrology transport models to understand and predict the movement of these pollutants. Some organic pollutants, like certain pesticides, can be more mobile in the groundwater system and may reach drinking water sources more easily due to their molecular structure, affecting their solubility and mobility.