Thallium dynamics in contrasting light sandy soils-Soil vulnerability assessment to anthropogenic contamination
Abstract
The influence of different soil conditions and the presence of LMWOA (Low Molecular Weight Organic Acids) on anthropogenic Tl dynamics were discussed in this study. A shift from the "labile" to the residual fraction during the ageing was identified, indicating Tl incorporation into stable phases (e.g., illite and/or amorphous silicates).
The increased water-soluble Tl concentration (1.8 fold, in maximum) after the split application of LMWOA was observed in all soils; partial dissolution of relatively "insoluble" Tl-bearing phases (silicates and eventually oxides) in the presence of LMWOA is suggested. Manganese(III,IV) oxides, illite and amorphous silicates were evaluated as the dominant phases responsible for Tl retention in the soils.
In carbonate-rich soils, Tl coprecipitation with the newly formed carbonates seems to be an important factor influencing Tl release. Therefore, we suggest data on CEC, pHZPC and soil mineralogy to be critical for assessment of Tl behavior in soils.