Are volcanos a major source of chlorine to the stratosphere?
No, volcanos contribute at most just a few percent of the chlorine found in the stratosphere. Direct measurements of the stratospheric chlorine produced by El Chichon, the most important eruption of the 1980’s (Mankin and Coffey, 1983), and Pinatubo, the largest volcanic eruption since 1912 (Mankin et. al., 1991) found negligible amounts of chlorine injected into the stratosphere.
