Which of the following is a common source of mercury pollution in aquatic environments?

Coal burning power plants are a significant source of mercury pollution in aquatic environments primarily because they emit mercury as a byproduct of burning coal. When coal is burned, it releases mercury that has been naturally present in the coal itself. This mercury can be carried into the atmosphere, where it can travel long distances before settling back to Earth through precipitation or atmospheric deposition. Once it lands in water bodies, this mercury can then undergo a process called methylation, where it is converted into methylmercury, a more toxic form that can bioaccumulate in fish and other aquatic organisms. This accumulation poses risks not only to wildlife but also to humans who consume contaminated fish.

While agricultural runoff and plastic waste are concerns for various types of pollution, they are not directly related to mercury contamination. Agricultural runoff typically involves pesticides and fertilizers, while plastic waste primarily contributes to physical pollution and can harm aquatic organisms through entanglement and ingestion. Oil spills, although harmful to marine environments, do not involve mercury specifically unless they are from sources that also have mercury contamination.

Therefore, coal burning power plants represent the primary and direct source of mercury pollution affecting aquatic ecosystems.