Determination of the parameters in the Freundlich function using a modified method in the case of the bioaccumulation factor of Populus tremula

Abstract

This study proposes a modified coefficient-estimation approach for the Freundlich function to model soil-to-leaf element transfer without relying on conventional logarithmic linearization. For this purpose, the leaf uptake capability of European aspen (Populus tremula L.), which grows abundantly in the Avliyana (Torul) region of Gümüşhane Province, one of Türkiye’s significant metallogenic zones, was investigated using this modified coefficient-estimation approach. This region has undergone hydrothermal alteration and ore mineralization, resulting in elevated concentrations of heavy metals compared to background levels. The soil-to-leaf regression curves obtained using the modified coefficient-estimation approach provided a closer representation of element transfer from soil to P. tremula leaves. Overall, the results indicate that estimating the a and b parameters directly in the original concentration scale provides leaf concentration estimates that are closer to the measured values than those obtained using the classical log-transformed Freundlich approach.