This study developed amodeling approach to evaluate potential non-point source (NPS) loading of PAHs from contaminated soils. THe main conclusions are as follows. First, the enrichment ratio (ER) model proposed by this study has been validated with experi-mental data, which suggested that the enrichment behavior of PAHs not only depends on their own physicochemical properties, but on the composition of soil carbonaceous materials (CMs) and how the composition evolves in the discharged sediment. Second, the ER model involves significant uncertainty with complex origins, and compound-dependent strategies are required to address the uncertainty. Third, with the ER model, it would be practical to evaluate the potential NPS loading of PAHs in watersheds with highly heterogeneous soils.
The study results are valuable to the innovation of NPS pollution models, as well as to manage the NPSpollution of PAHs (probably other chemicals alike as well). Nevertheless, many important issues remain to be studied.for example, the enrichment behavior of typical soil CMs has been rarely invastigated. To reduce the notable parametric uncertainty of the model, more data on the partition coefficients need to be collected. How to incorporate the ER model into classic NPS pollution models like SWAT also deserves further studies.