Sequential multistep procedure, usually used for the fractionation and characterization of soil organic matter was tested
for Hg content in the individual steps and fractions. Under general laboratory conditions serious problems have arosen during
the attempt in the Hg mass balance calculation. Several sources of Hg contamination were recognized. The most serious was
the background concentration of Hg even in research grade chemicals (what is in general not declared) and laboratory air.
The work on operational Hg speciation as non-humic bound, humic acid, fulvic acid bound proceeds from the established status-quo
on distribution of mercury of soil organic matter.