Parameter Tree:
EARTH SCIENCE > LAND SURFACE > SOILS > HEAVY METALS

Definition:
Those metals which have densities >5.0 Mg m-3. In soils these include the
elements Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, and Zn.


Reference:
From the Glossary of Soil Terms/Soil Science Society of America (SSSA):
http://www.soils.org/sssagloss/