Description
Previously in our laboratory, an experiment was conducted examining organic contaminants on plastic debris found on beaches in San Diego County. Analysis showed that there was consistently greater PAH concentrations (30-1900 ng g-1) in the samples when compared to other targeted persistent organic pollutants. Furthermore, among the different types of plastic, polystyrene (PS) foam contained the greatest concentration of PAHs. Unexposed PS foam (240-1700 ng/g) had significantly higher PAH concentrations compared to PS virgin pellets (12-15 ng/g). These results led to the present study aimed at examining PAH patterns across different types of foam both exposed and unexposed to a marine environment. The main objective was to (1) compare PAH profiles among three different types of foam: soft PS foam, hard PS foam and polyurethane foam and (2) to compare PAH profiles before and after deployment of the three types of foam in the San Diego Bay. For three months, five replicates of each of three types of foam (hard PS, soft PS and polyurethane) were deployed in San Diego Bay, CA. Another five replicates of each type were never exposed to the bay and were immediately stored at -20oC. Differences in PAHs between types of foam and between those exposed to the bay were analyzed by GC_GC/TOF-MS for the presence of PAHs and other non-targeted analytes. The numbers of peaks found in the samples prior to deployment samples were 2105 (soft PS), 1319 (hard PS), and 4375 (polyurethane). The numbers of peaks found in the samples after deployment are 1220 (soft PS), 930 (hard PS), 3091 (polyurethane). The numbers of aromatic compounds found in the samples prior to deployment were 359 (soft PS), 207 (hard PS), and 495 (polyurethane). The numbers of aromatic compounds found in the samples after deployment were 294 (soft PS), 105 (hard PS), and 274 (polyurethane). The numbers of PAHs found in the samples prior to deployment are 21 (soft PS), 18 (hard PS), and 75 (polyurethane). The numbers of PAHs found in the samples after deployment are 21 (soft PS), 10 (hard PS), and 51 (polyurethane). In all foams after deployment there were less peaks when compared to before deployment. A trend of increasing PAH concentration after deployment for analytes with a 4 or more aromatic rings as well as a trend of decreasing concentrations after deployment for analytes with a 3 or 2 aromatic rings and all foams were found to have alkylated naphthalene's in samples before deployment. These findings suggest that large PAHs are absorbed onto the plastic foams from the marine environment, while smaller PAHs are desorbed to the marine environment. As found in other studies, PAHs of large molecular weight will be more hydrophobic making it harder to dissolve in ocean water and bioavailable to aquatic life, thus making plastics an agent to transport the hydrophobic contaminants to the marine environment
