Which statement correctly distinguishes wet deposition from dry deposition, and provides a representative example?

• A. Wet deposition is long-range; Dry deposition is local.
• B. Wet deposition removes pollutants via precipitation; Dry deposition deposits gases/particles directly to surfaces.
• C. Wet deposition deposits on surfaces; Dry deposition removes pollutants via precipitation.
• D. Wet deposition only affects aerosols; Dry deposition only affects pollutants.

Answer: (B)

Deposition processes in the atmosphere differ by how pollutants are removed from the air and reach surfaces. Wet deposition removes pollutants through precipitation, meaning rain or snow scavenges soluble gases and particles from the air and deposits them on the ground or water. Dry deposition deposits gases and particles directly onto surfaces without precipitation, such as onto leaves, soil, or building surfaces. A good example of wet deposition is rain removing soluble pollutants like sulfate or nitrate from the atmosphere, contributing to acid rain. A good example of dry deposition is gases like ozone or sulfur dioxide and fine particulates settling onto vegetation or other surfaces without any rain.

Other statements either mix up the mechanisms, imply only aerosols are involved, or suggest deposition occurs only in one mode, which doesn’t fit how these processes operate in the atmosphere.