Air And Water Pollution Control (AWPC) Exam 2 Practice

Which statement correctly describes the typical behavior of LNAPL and DNAPL at a contaminated site?

LNAPL rises to the surface and DNAPL sinks. DNAPL rises to the surface and LNAPL sinks. Both rise to the surface. Both sink.

Correct Answer:

LNAPL rises to the surface and DNAPL sinks.

Explanation:

The typical behavior is controlled by density relative to water. LNAPL is lighter than water, so it is buoyant in the subsurface and tends to rise through the vadose and saturated zones, accumulating at the water table or reaching the surface. DNAPL is heavier than water, so it sinks through the saturated zone until it encounters an impermeable layer or low-permeability pocket where it can pool. That’s why the correct statement is that LNAPL rises to the surface while DNAPL sinks. The other possibilities fail because they contradict the buoyancy differences: DNAPL would not rise, and LNAPL would not sink.

Access more questions from this quiz

Continue to Air and Water Pollution Control (AWPC) Exam 2 Practice for more practice questions and the full quiz experience.

Access More Questions