Modeling Metal Binding to Soils:  The Role of Natural Organic Matter

Abstract

The 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.

Assessment of the content of heavy metals and potential pathogenic microorganisms in soil under illegal dumping sites

“…Durability of chelates depends on the pH of the soil and the type of metal ion. Creating organometallic A, B, C described in Table 1 CF contamination factor, CF in C deg degree of contamination, AF availability factor complexes in the soil is very important in order to prevent the toxic metal ions leaching the soil, and it also detoxifies and reduces uptake of the toxins by plants (Gustafsson et al 2003). To confirm such interdependencies, a correlation analysis was performed, which showed a significant positive correlation between the content of organic carbon and the content of total amount of copper (r = 0.573, P \ 0.05), lead (r = 0.615, P \ 0.05) and nickel (r = 0.705, P \ 0.05; Table 9).…”

“…The results show that the most dangerous bacteria exist in the soil under the C landfill and this is where the greatest risk of soil contamination exists. Increasing the amount of organic matter in the soil under C helps to minimize the absorption of heavy metals by microorganisms The formation of metal-organic complexes in soil is very important due to the prevention of leaching of toxic ions of heavy metals from soil, as well as their partial detoxication and limiting the uptake by microorganisms (Gustafsson et al 2003;Khan et al 2010). …”

Predicting cadmium adsorption on soils using WHAM VI

“…48 SOM has been reported to be the major component among soil components accounting 49 for metal binding. Furthermore, it has been reported that only a fraction of SOM, which is 50 called active organic matter (AOM), is responsible for metal binding (Tipping et al, 2003; 51 Gustafsson et al, 2003;Lumsdon, 2004). The AOM may be due to the difference 52 absorption spectrometry as reported by Lee et al (1996).…”

Silver(I) Binding Properties of Organic Soil Materials Are Different from Those of Isolated Humic Substances

“…generic values for proton and metal binding constants have been derived from calibration of these models on isolated fulvic and humic acids 21 . This approach has proven to be successful for a range of metal ions, such as Al 3+ , Fe 3+ , Cu 2+ , Zn 2+ and Cd 2+ , [22][23][24][25][26] but has not yet been tested for Ag + . Furthermore, there are just a few published data sets available for silver(I) binding by humic and fulvic acids.…”