From a theoretical viewpoint, computational chemistry provides insight into processes at the molecular level and expands the understanding of the pollutant-SOM interaction. The modeling of SOM is challenging due to its heterogeneity and complexity, which has led to the ongoing development of various SOM models . The Vienna Soil Organic Matter Modeler 2 (VSOMM2) was recently released, which allows model systems of condensed phase HS to be generated, following a building block approach. Based on elemental and organic fractions as input parameters, heterogeneous systems of HS with different compositions can be investigated, thus approaching the properties of real SOM.