Background: Mercury (Hg) is a global contaminant and threatens public health in developing and developed countries. Low concentrations can be hazardous threat to humans and wildlife because of its ability to bioaccumulate. Soils are critical in the global Hg cycle. Understanding the patterns and processes of Hg in soils is essential as they: (1) accumulate and release atmospheric Hg, (2) hold vast quantities of Hg in subsurface horizons and (3) may methylate Hg to its more toxic methyl-Hg form. This problem encompasses processes from molecular to landscape scale and thus requires many divisions of soil science to adequately address.