What term refers to the breakdown of chemicals by the action of sunlight?

The term that describes the breakdown of chemicals through the action of sunlight is photodegradation. This process occurs when solar radiation, particularly ultraviolet light, interacts with chemical compounds, leading to their transformation or degradation. Photodegradation is a significant factor in the environmental fate of many chemicals, including pesticides, as it can greatly influence their persistence and effectiveness in the environment.

Biodegradation, on the other hand, refers to the breakdown of substances by living organisms, typically microbes, and is not specifically linked to sunlight. Thermal degradation involves the breakdown of compounds due to heat, while chemical degradation generally refers to the process by which a chemical compound is transformed into different chemicals through various reactions, not necessarily influenced by sunlight.