Spatial distribution and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in surficial sediments along the coast of British Columbia, Canada

The 29,000 km coastline of British Columbia (B.C.), Canada, is an area with increasing industrial and shipping activity. Pollution Tracker is the first coast-wide marine pollution monitoring program, generating high resolution contaminant data for sediment samples. Surficial sediment samples were collected as part of the Pollution Tracker Program from 51 sites between 2015 and 2017. Polycyclic aromatic hydrocarbons (PAHs) were detected at all sites, with total PAHs (75 analytes) ranging from 36 to 162,000 nanograms (ng) per gram (g) dry weight (dw). Sediment samples from Prince Rupert Harbour (162,000 ng/g dw) and Victoria Harbour (21,000–47,000 ng/g dw) had the highest PAH levels, consistent with heavy vessel traffic, and a history of urban and marine activities in those areas. Of the 51 sites, 25 % exceeded Canadian marine interim sediment quality guidelines for all 13 PAH analytes. Mean probable effects level quotient values (PEL-Q) indicated 69 % of sites had potential ecological risk associated with PAH exposure from sediment, 25 % of sites had moderate risk, and two sites were categorized as having a high risk of biological effects. Source ratios of four ring and larger parent PAHs indicated combustion is the primary contributor to the hydrocarbon sediment profile, with most samples containing mixed biomass/solid fuel and liquid fuel combustion sources. Correspondingly, petrogenic source apportionment using alkyl naphthalene isomers suggested most samples contained PAHs from both coal and oil sources. Our high-resolution baseline data provides further insight into the sources and fate of PAHs in coastal B.C. marine sediment.