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PCB concentrations in upper and lower New Bedford Harbor
PCBs showed up initially in the upper harbor in the late 1930s and in the lower harbor in the early 1940s. Dating methods give approximate dates, so this difference may not be real. Aerovox Corporation, the source of the PCBs, moved into an empty mill building on the upper harbor in 1939 (yellow triangle in Fig. 19). When PCBs enter the harbor waters they are quickly adsorbed onto sediment particles, which then can be moved by outgoing tides, settle to the bottom, get resuspended, and moved again further down the harbor (see Fig.13 for distribution of PCBs in harbor). Note the difference in scales of PCB concentration; the maximum concentration of PCBs in the upper harbor (186µg/g) is about ten times greater than that in the lower harbor (17.6µg/g).
