Using positive matrix factorization to unmix PAH fingerprints in contaminated sediments

Some of the challenges to apportioning PAH-related remedy costs at contaminated sediment sites include the lack of source samples, different PAH signatures associated with the same source, historical PAH sources long removed, mixing of urban sediment by boat traffic, and, in turn, PAHs mixing and weathering. Unmixing of PAH fingerprints in sediment sites to PAH source classes (petrogenic, pyrogenic, and runoff) is typically a first step to tracking PAH upland sources and ultimately, responsible parties. This work demonstrates using positive matrix factorization (PMF) as a method to unmix PAH fingerprints to its source classes.A large PAH dataset (over 700 samples) assembled from contaminated urban sediment sites was used as an input to PMF. Using a 3-factor PMF analysis, a petrogenic, pyrogenic, and runoff/weathered PAH end-member fingerprints were identified. Different numerical mixing percentages of the PMF-identified end-member sources were able to replicate the sediment-measured PAH fingerprints, with the percent contribution of each of the end members to each sediment sample calculated. The demonstrated work provides a method to satisfy the unmixing of PAH fingerprints to its source classes, as a step towards apportioning of PAH contamination.