| Urban rivers with a history of industrial use can exhibit spatial and temporal variations in contaminant concentrations that may significantly affect risk evaluations and assessment of remediation efforts. To more effectively estimate human and ecological health risks, we evaluated the spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in an urban river using low-density polyethylene passive sampling devices (PSDs). PSDs simulate cell membranes and lipid tissue and accumulate only freely dissolved, and thus, bioavailable contamination. Using PSDs and high-pressure liquid chromatography we measured bioavailable concentrations of 15 priority pollutant PAHs over five years along 18.5 miles of the lower Willamette River including the Portland Harbor Superfund megasite. This area contains several PAH sources including coal tar and creosote sites, which underwent remediation during this study. Additional potential sources of PAHs include combined sewer overflows, urban runoff, atmospheric deposition and petroleum product leaks and spills. Results reveal increased urban bioaccessible PAH loading during wet seasons and high rain events, successful capping of the McCormick and Baxter Superfund site, increased bioavailable PAHs during dredging operations, and the potential for using PSDs for source apportionment. PAH concentrations, loads, and congener ratios changed significantly depending on location, river flow, precipitation, and contaminant removal activities. Our research demonstrates that human and ecological risk varies significantly by season and remediation technique. Additionally, our refined analytical method eliminated 80% of organic solvents and 100% of chlorinated solvents from the sampling method and also reduced labor and cost. Health professionals can apply the findings and refined technology to more effectively assess exposure to pollution. |
