es026249t_si_001.pdf (80.26 kB)
Modeling Metal Binding to Soils: The Role of Natural Organic Matter
journal contribution
posted on 2003-05-16, 00:00 authored by Jon Petter Gustafsson, Pavlina Pechová, Dan BerggrenThe use of mechanistically based models to simulate the
solution concentrations of heavy metals in soils is complicated
by the presence of different sorbents that may bind
metals. In this study, the binding of Zn, Pb, Cu, and Cd by
14 different Swedish soil samples was investigated. For
10 of the soils, it was found that the Stockholm Humic Model
(SHM) was able to describe the acid−base characteristics,
when using the concentrations of “active” humic
substances and Al as fitting parameters. Two additional
soils could be modeled when ion exchange to clay was also
considered, using a component additivity approach. For
dissolved Zn, Cd, Ca, and Mg reasonable model fits were
produced when the metal-humic complexation parameters
were identical for the 12 soils modeled. However, poor fits
were obtained for Pb and Cu in Aquept B horizons. In
two of the soil suspensions, the Lund A and Romfartuna
Bhs, the calculated speciation agreed well with results
obtained by using cation-exchange membranes. The results
suggest that organic matter is an important sorbent for
metals in many surface horizons of soils in temperate and
boreal climates, and the necessity of properly accounting
for the competition from Al in simulations of dissolved metal
concentrations is stressed.