Final answer:
Scientists know that the chlorine in the stratosphere is not primarily from volcanoes due to the presence and impact of industrial chemicals like CFCs. These chemicals, used in processes like refrigeration and air conditioning, break down and release chlorine atoms that destroy ozone molecules. While volcanic activity does release sulfur aerosols that also contribute to ozone depletion, CFCs are the primary source of chlorine in the stratosphere.
Step-by-step explanation:
Scientists know that the chlorine in the stratosphere is not primarily from volcanoes due to the presence and impact of chlorofluorocarbons (CFCs) and other industrial chemicals. These chemicals have been used in processes like refrigeration and air conditioning, and when they are released into the atmosphere, they break down and release chlorine atoms that destroy ozone molecules. The destructive effect of chlorine on ozone is a well-documented chain reaction that depletes ozone in the stratosphere. While volcanic activity does play a role in releasing sulfur aerosols that can also contribute to ozone depletion, the impact of CFCs and industrial chemicals has been found to be the primary source of chlorine in the stratosphere.