engleski

Predicting free metal ion concentrations of Cd in uncontaminated Croatian soils by applying established regression models

Free metal ion (FMI) concentrations have recently been recognized as good indicators of plant metal availability. Several researchers have developed regression models predicting FMI concentrations of Cd in contaminated and slightly contaminated soils. We have extracted soil samples collected from uncontaminated soils located in eastern Croatia using H2O and determined the solution concentrations of Cd in these extracts. Free metal ion concentration of Cd was estimated using WHAM Model VI. We used these data to test the applicability of two regression models for the existing conditions. The same predictors used in two comparing models and the same regression coefficients were provided for the present study. The results showed a good correlation between the observed and predicted concentrations of FMI. However, the models overestimate FMI concentrations, and therefore the same regression coefficients were optimized to derive the best-fit model. This was found to be very successful and our predictions were following 1:1 regression line through zero, indicating no overestimations. The results showed that pH and M(tot) were significant in predicting FMI concentrations, while SOM was somewhat less significant. However, SOM was also included in our model as it was in two comparing models.

cadmium ; free metal ion ; modeling ; trace elements

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