The majority of atmospheric mercury is produced by

Atmospheric mercury is produced by burning of coals where it accumulates on crops resulting in ingestion.

Explanation:

Since it is poisonous, when ingested it causes health problems that affect the reproductive system, immune system, nervous system, etc.  

Other mercury contributing sources are gold mine operations, burning processes in the incinerators, and industrial boilers. In the US, coal combustion is the highest source of the atmospheric mercury accounting 50%. Asia also emits mercury at a high rate due to a lot of coal-powered incinerators.

Mantle convection is the process that drives plate tectonics. the theory of plate tectonics states that the crust is divided into plates that float on the semi molten mantle below. the circular motion of the magma as it slowly rises and falls or move though convection cells drags the plates along causing them to move. the heat source in the lamp would represent the earth's core. the core is the source of energy that drives convection in the mantle. the lava represents molten magma under the earth's surface. if the lava lamp had floating pieces they would move as the circular motion of the lava in the lamp as it rises and falls would move them along the surface. these floating pieces would represent pieces of the earth's crust.