Urban areas are important regional sources of airborne polychlorinated biphenyls (PCBs) and population-scale airborne exposure, yet a comprehensive bottom-up source inventory of PCB emissions has never been quantified at urban scales in the United States. Here we report a comprehensive parcel level inventory of PCB stocks and emissions for Chicago, Illinois, developed with a transferable method from publicly available data. Chicago’s legacy stocks hold 276 ±147 tonnes ΣPCBs, with 0.2 tonnes added annually. Transformers and building sealants represent the largest legacy categories at 250 and 20 tonnes, respectively. From these stocks, annual emissions rates of 203 kg for ΣPCBs and 3 kg for PCB 11 explain observed concentrations in Chicago air. Sewage sludge drying contributes 25% to emissions, soils 31%, and transformers 21%. Known contaminated sites account for <1% of stocks and 17% of emissions to air. Paint is responsible for 0.00001% of stocks but up to 7% of ΣPCBs emissions. Stocks and emissions are highly concentrated and not correlated with population density or demographics at the neighborhood scale. Results suggest that strategies to further reduce exposure and ecosystem deposition must focus on the largest emissions sources rather than the most contaminated sites or the largest closed source legacy stocks.
Outer membrane vesicles (OMVs) are 20‐250 nm particles released from Gram‐negative bacteria, including commensal and pathogenic Escherichia coli(E. coli). OMVs contain outer membrane and periplasmic proteins, toxins, nucleic acids, and pieces of peptidoglycan. OMV production is enhanced by environmental stressors, and OMVs are thought to facilitate bacterial cell growth and division, to contribute to bacterial communication (quorum sensing), and can also act as decoys during antibiotic or host immune system attacks. We aim to optimize E. coli OMV production and purification using ultracentrifugation and alternative techniques, to characterize OMVs using immunoblotting and nanoparticle tracking analysis (NTA), and to ultimately determine how OMVs can be used as molecular biomarkers for E. coli infections and Gram‐negative sepsis. Preliminary studies have shown that antibodies to peptidoglycan associated lipoprotein (Pal) can be employed to successfully identify E. coli OMVs.
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