What is the main source of chlorine in the atmosphere?

What is the main source of chlorine in the atmosphere?

• A. Natural volcanic emissions
• B. Atmosphere nitrogen reactions
• C. Oceans releasing chlorine
• D. Emissions of chemicals by humans like CFCs

Answer: (D)

Chlorine in the atmosphere mainly comes from human-made halogenated compounds, especially CFCs. These chemicals are very stable and rise into the upper atmosphere where UV light breaks them apart, releasing chlorine atoms. Those chlorine atoms drive catalytic cycles that destroy ozone, so the total atmospheric chlorine load is dominated by the chlorine released from CFCs and similar industrial molecules. Natural sources like oceanic sea salt aerosols and volcanic emissions do contribute chlorine, but their overall impact is much smaller than the large, long-lasting chlorine burden from human-made halocarbons.

Chlorine in the atmosphere mainly comes from human-made halogenated compounds, especially CFCs. These chemicals are very stable and rise into the upper atmosphere where UV light breaks them apart, releasing chlorine atoms. Those chlorine atoms drive catalytic cycles that destroy ozone, so the total atmospheric chlorine load is dominated by the chlorine released from CFCs and similar industrial molecules. Natural sources like oceanic sea salt aerosols and volcanic emissions do contribute chlorine, but their overall impact is much smaller than the large, long-lasting chlorine burden from human-made halocarbons.