Stable chlorine isotopic compositions of aroclors and aroclor-contaminated sediments

TitleStable chlorine isotopic compositions of aroclors and aroclor-contaminated sediments
Publication TypeJournal Article
Year of Publication2000
AuthorsReddy, CM, Heraty, LJ, Holt, BD, Sturchio, NC, Eglinton, TI, Drenzek, NJ, Xu, L, Lake, JL, Maruya, KA
JournalEnvironmental Science & Technology
Date PublishedJul 1
Accession NumberWOS:000087974200046

An exploratory investigation was conducted to evaluate if stable chlorine isotopic ratios of polychlorinated biphenyls (PCBs) could be useful in studying the processes that determine their transport and fate in the environment First, we determined the variability of delta(37)Cl in the source materials for PCBs. Second, we determined if the delta(37)Cl values of contaminated environmental samples fell outside the range in source variability. The isotopic variability among the source materials (Aroclors) was rather small; delta(37)- Cl values ranged from -3.37 to -2.11% (mean and standard deviation, -2.78 +/- 0.39%, n = 12). There was no correlation between the delta(37)Cl values and percentages of chlorine in the mixtures. We also found very similar values in several Clophen mixtures and one Phenoclor. The delta(37)Cl values in the total PCBs isolated from Aroclor-contaminated sediments from the Hudson River, New Bedford Harbor, and Turtle River Estuary ranged from -4.54 to -2.25% (n = 19). While most of the delta(37)Cl values were within 2 standard deviations of the mean Aroclor value (our assumed estimate for overall source variability), two of the PCB contaminated sediment samples from New Bedford Harbor did appear to be isotopically distinct. The PCBs in these sediments had lower amounts of less chlorinated congeners (when compared to the source material) and were likely isotopically affected by alteration processes that preferentially removed these congeners. Compound specific measurements of two congeners in Aroclor 1268 suggest that there are no large congener-specific differences in the stable chlorine isotope ratios in Aroclors. This study shows that the delta(37)Cl Values of PCBs may be a potentially useful diagnostic tool in studying the transport and fate of PCBs and indicates that additional research is warranted.