The major source of mercury emissions into the atmosphere is from:

Coal burning is indeed the major source of mercury emissions into the atmosphere. When coal is burned for electricity generation, it releases mercury that is naturally occurring in the coal’s composition. This mercury is emitted as a vapor and can travel long distances from the source before eventually settling into water and soil, contributing to environmental contamination and posing health risks to humans and wildlife.

While other options represent sources of mercury emissions, they are not as significant on a global scale as coal combustion. For instance, evaporation from paints during drying can release some mercury, but this contribution is negligible compared to the extensive emissions produced by coal burning. Similarly, while burning of industrial wastes can release mercury depending on the waste composition, it doesn't approach the volumes emitted by coal-fired power plants. Dust from mining operations can contain mercury, especially in areas where mercury is mined or naturally present, yet again, it does not match the output from the coal industry, which remains a leading contributor to atmospheric mercury levels. Thus, coal burning stands out as the primary contributor to mercury emissions.