The effect of minerals on non-ionic compound sorption by changing the sorption capacity of soil organic matter

For non-ionic compounds, the preliminary role in the sorption process is played by soil organic matter (SOM). However, it is necessary to determine the relative contribution of soil minerals, in particular, soil clay minerals and SOM constituents, to improve prediction of the sorption process. Here, the results show that sorption capacity of SOM can be affected by mineral-SOM interaction. The organic carbon-normalized sorption coefficient (K-oc) after hydrofluoric acid (HF) treatment increased an average of 124% and 98% for A11 horizons and 185% and 162% for A12 horizons for diuron and phenanthrene, respectively. We propose that the increased K-oc values in the A12 horizons are due to a higher percentage of clay in A12 horizons as well as a loose connection of SOM with clay minerals in A11 horizons. We suggest that the mineral components of soil contribute greatly to sorption of even non-ionic compounds with alteration of the sorption properties of SOM, which need to be considered in determining the fate and availability of non-ionic compounds in the soil environment.