K OC -WebPredictor: An Open-Access Tool for Prediction and Insights into Soil Sorption
Lu Li, Sk. Abdul Amin, Supratik Kar, Stefano Piotto · ACS Omega · 2026
High Resolution Image Download MS PowerPoint Slide The soil organic carbon–water partition coefficient ( K OC ) is a key determinant of the environmental mobility and persistence of organic contaminants. Experimental measurement of K OC is accurate but resource-intensive, limiting its availability for the vast chemical inventory in commerce. Here, we developed interpretable quantitative structure–activity relationship (QSAR) and quantitative Read-Across Structure–Activity Relationship (q-RASAR) models, along with machine learning (ML) approaches, to predict log K OC values using reproducible 1D and 2D molecular descriptors. The optimized multiple linear regression (MLR)-based QSAR model, built on 824 structurally diverse compounds and nine mechanistically relevant descriptors, achieved strong internal and external performance ( R 2 = 0.85, Q 2 LOO = 0.84, and Q 2 F1 = 0.84). Comparative statistical evaluation using paired t- and Wilcoxon signed-rank tests confirmed that the QSAR model significantly outperformed the q-RASAR variant ( p < 0.05) in predictive accuracy and robustness. Mechanistic interpretation revealed that hydrophobicity, aromatic rigidity, and halogenation increase soil sorption, whereas polar or phosphorus-rich substituents promote mobility. Large-scale external screening of 7,612 chemicals from the U.S. EPA’s CPDat inventory showed 94% coverage within the applicability domain (AD), supporting data gap filling under regulatory frameworks. An open-access web tool, K OC -WebPredictor, was developed to deliver quantitative (QSAR-based) and qualitative (ML-based) predictions, with visualization taking AD into consideration. This integrated, interpretable platform provides a practical alternative to experimental assays for assessing soil–organic carbon interactions and prioritizing chemicals based on mobility potential.