By David Nichols

Faculty Mentor: Dr. Ben Kisila

Abstract

Polycyclic aromatic hydrocarbons (PAH) are a class of carcinogenic, persistent organic pollutants that are primarily derived from the partial combustion coal and petroleum products such as coal-tar sealant or gasoline. Increasing population in Northern Virginia and the coinciding acceleration of urban and suburban development have increased road development and usage increasing the potential release of associated PAHs to nearby aquatic ecosystem. 82 sediment grab samples and 4 sediment cores in Northern Virginia waterways (Potomac, Rappahannock, and Occoquan Rivers) were used to evaluate spatial and temporal variability in PAH. Analysis was done for methylphenanthrene and the 16 PAHs that the United States Environmental Protection Agency has identified as most prevalent in sediment (EPA16). Samples were extracted using accelerated solvent extraction (ASE) and analyzed using gas chromatography mass spectroscopy (GC-MS). Statistical analysis was done using Pearson correlation analysis (PC), principal component analysis (PCA), and the ratio of methylphenanthrene to phenanthrene (MP/P) was used to estimate the origin of PAH. Total PAH concentration, proximity to common sources of PAHs, and large urban areas was analyzed for spatial correlation, along with the relationship between individual PAHs from each sample.
The preliminary results show that total PAH concentration ranged from 25.2 ppb to 10100 ppb. PCA results showed that methylphenanthrene and methylnaphthalenes were correlated together, while the total PAH concentration correlated more with high molecular weight PAHs. PC showed that waste processing plants and coal ash deposits were found as potential point sources of PAH. Temporal data provided by sediment cores and the changes between the preliminary and concurrent samples will potentially provide historical variability on PAH concentration.