Which of the following processes is NOT involved in the breakdown of pesticides after application?

Thermal degradation refers to the breakdown of substances through the application of heat, which is not a primary process involved in the degradation of pesticides after they have been applied to the environment. The breakdown of pesticides mainly occurs through biological and chemical processes.

Photodegradation involves the breakdown of pesticides due to exposure to sunlight, which can cause chemical changes in the pesticide molecules. Microbial degradation is a vital process where microorganisms, such as bacteria and fungi, consume and transform pesticides, breaking them down into less harmful substances. Chemical degradation involves reactions with other chemicals in the environment, like water or soil components, leading to the breakdown of pesticides.

Since these processes - photodegradation, microbial degradation, and chemical degradation - are integral to how pesticides are degraded naturally, thermal degradation does not typically play a role in this context after application.