Sedimentary records of non-Aroclor and Aroclor PCB mixtures in the Great Lakes

Abstract

Three sediment cores from Lake Ontario, Lake Erie and Indiana Harbor Ship Canal were collected, segmented and analyzed for Aroclor and non-Aroclor polychlorinated biphenyl congeners (PCBs). PCBs associated with the commercially produced Aroclor mixtures 1248 and 1254 dominate the sediment signal and the sum of all congeners (ΣPCB) peaks in concentration and accumulation around 1970 in the Great Lakes. This trend is very similar to Aroclor production history. In the Indiana Harbor Ship Canal, PCBs appear around 1935 and remain at very high levels between 1940 and 1980, probably reflecting the history of use at the nearby steel mill. In contrast, the non-Aroclor PCBs in the Lake Ontario and IHSC sediment cores, including PCB11 and heavily chlorinated congeners PCB206, 207, 208 and 209 reach a peak in the 1950s, decline and peak again in the 1970s or in the early 1980s. All five congeners have been previously measured in commercial paint pigment. PCB11 was found to peak about 5 years later than ΣPCBs, and is probably associated with the production or use history of diarylide yellow pigments. The temporal distribution profiles of these non-Aroclor PCBs are well correlated with the production history of paint pigments and dyes. Although it is well known that the production of Aroclor PCBs is preserved in Great Lakes sediments, this study is the first to show that production of non-Aroclors are also preserved in the sediments as a record of long term trends in environmental exposure.

Trends of PCB concentrations in Lake Michigan coho and chinook salmon, 1975–2010

“…The exponential decay rates estimated by French et al equate to annual percentage changes of −7.87% for chinook and −9.61% for coho. While PCB trends exhibited by different Lake Michigan species, media or time periods are expected to differ (Hu et al, 2011;Lamon et al, 2000), our estimates may best reflect the more recent PCB reductions in Michigan salmon. This information should be useful in evaluating contemporary efforts to reduce PCB sources to Lake Michigan.…”

“…PCBs are highly lipophilic and bioaccumulate in fish including commonly consumed predator species such as walleye, bass, and salmon (Carlson and Swackhamer, 2006;Gewurtz et al, 2011). After PCB use and manufacture was banned in the United States in 1977, direct environmental exposure of humans decreased (Hu et al, 2011;Knobeloch et al, 2008). However, exposure via consumption of fish from contaminated waters remains a concern.…”

“…However, exposure via consumption of fish from contaminated waters remains a concern. Lake Michigan has the highest PCB concentrations of all the Great Lakes (Carlson and Swackhamer, 2006;Hu et al, 2011). All states bordering Lake Michigan continue to issue consumption advisories for Lake Michigan fish due to PCB concentrations.…”

“…While PCB concentrations in lake fishes dropped markedly following restrictions on PCBs' manufacture, use, and disposal, recent trends display more moderate declines (Bhavsar et al, 2007;Chang et al, 2012;Hickey et al, 2006;Hu et al 2011). Modeling trends of PCBs in Lake Michigan fish are a potential way to evaluate efforts to remediate ongoing sources of PCBs to Lake Michigan in light of other factors that also affect PCB concentrations in fish (i.e.…”

Recognizing different impacts of human and natural sources on the spatial distribution and temporal trends of PAHs and PCBs (including PCB-11) in sediments of the Nador Lagoon (Morocco)

“…Among non-Aroclor PCBs (CB-11, CB-206, CB-207, CB-208 and CB-209; Hu et al, 2011), only CB-11 was detected at significant levels (Tables S4-6 in the Supplementary material). Percent CB-11 contributions to the total concentrations range from b d.l.…”