In memoriam, Paul Crutzen (1933 - 2021)

摘要

He was awarded the Nobel Prize for his work on stratospheric ozone depletion by the catalytic nitrogen cycle. This was controversial at the time. The prevailing theory was based on ozone loss through photodisso-ciation, while competing theory focussed on catalytic loss by hydroxyl radicals (OH, HO2). In 1970 Crutzen demonstrated that nitrogen oxides are the dominant loss mechanism in the mid-stratosphere (20 - 40 km). Subsequently, in 1974, Mario Molina and Sherwood Rowland showed that chlorofluorocarbons also deplete stratospheric ozone, based on a third catalytic cycle involving halogens. The 1995 Nobel Prize was shared with Molina and Sherwood.