PCBs in Great Lakes sediments, determined by positive matrix factorization (original) (raw)
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Environmental Science & Technology, 2006
Nine sediment cores were collected from the Sheboygan River Inner Harbor, WI, and analyzed for polychlorinated biphenyl (PCB) congeners. Total PCBs ranged from ∼0 to 161 mg/g. Positive matrix factorization (PMF) was applied to the PCB data set to determine source profiles. Two factors were determined to be significant. One factor resembled the original approximated PCB mixture of 50% Aroclor 1248 and 50% Aroclor 1254 and the other factor was a dechlorinated version of the mixture. An anaerobic dechlorination model was applied to the dechlorinated source profiles to quantify possible dechlorination pathways. It was found that dechlorination process H′ provided the best fit for an individual process, and H′ + M provides the best fit for combined processes. PMF source contributions, and plots of PCB concentration versus congener for individual samples, provide evidence of enhanced dechlorination at high concentrations (>40 ppm) and small amounts of dechlorination at low concentrations (<3 ppm). In addition, downward migration of lower chlorinated PCBs in core SR1a has occurred. Remediation dredging in the Upper Sheboygan River in 1989 and 1990 reintroduced PCBs to the water column and selective transport of PCB 18 is observed in core SR7.
Sedimentary records of non-Aroclor and Aroclor PCB mixtures in the Great Lakes
Lancet, 2011
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 (∑ PCB) 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 ∑ PCBs, 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.► Non-Aroclor PCB congeners (e.g., PCBs11, 206, 207, 208, 209) were detected in the sediments. ► Non-Aroclor PCB congeners have a different source from ΣPCBs. ► ΣPCB concentration trends reflect manufacture and use of commercial Aroclor mixtures. ► Local use of Aroclors is preserved in the sediments. ► The production of pigments and dyes matches the accumulation of inadvertent PCB congeners.
Environmental Science & Technology, 2015
We investigated the major sources of polychlorinated biphenyls (PCB) and interpreted the environmental fate processes of these persistent organic pollutants in the past and current PCB contamination of three large, urbanized, French peri-alpine lakes. Dated sediment cores were analyzed in order to reconstruct and compare the historical contamination in all three lakes. Stratigraphic changes of PCB contents and fluxes were considered as revealing the temporal dynamics of PCB deposition to the lakes and the distribution of the seven indicator congeners (further referred to as PCBi) as an indicator of the main contamination origin and pathway. Although located within a single PCB industrial production region, concentration profiles for the three lakes differed in timing, peak concentration magnitudes, and in the PCBi congeners compositions. PCBi fluxes to the sediment and the magnitude of the temporal changes were generally much lower in Lake Annecy (0.05−2 ng•cm −2 •yr −1) as compared to Lakes Geneva (0.05−5 ng•cm −2 •yr −1) and Bourget (5−290 ng•cm −2 •yr −1). For all three lakes, the paramount contamination occurred in the early 1970s. In Lakes Annecy and Bourget, PCB fluxes have declined and plateaued at 0.5 and 8 ng•cm −2 •yr −1 , respectively, since the early 1990s. In Lake Geneva, PCB fluxes have further decreased by the end of the XX th century and are now very low. For the most contaminated lake (Lake Bourget), the high PCBi flux (5−290 ng•cm −2 •yr −1) and the predominance of heavy congeners for most of the time period are consistent with a huge local input to the lake. This still high rate of Lake Bourget is explained by transport of suspended solids from one of its affluents, polluted by an industrial point source. Intermediate historical levels and PCBi distribution over time for Lake Geneva suggest a mixed contamination (urban point sources and distant atmospheric transport), while atmospheric deposition to Lake Annecy explains its lowest contamination rate. The presently low contamination levels recorded in Lake Geneva correspond to atmospheric inputs, but the recent PCBi distribution of Lake Annecy, enriched in relatively heavy congeners, reveals a contamination by the neighboring Lake Bourget, following a halo effect of about 40 km radius.
Legacy polychlorinated organic pollutants in the sediment of the Great Lakes
Journal of Great Lakes Research, 2018
Legacy, organic pollutants, including polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), and diphenyl ethers (PCDEs) were quantified in sediments of the Laurentian Great Lakes of North American. A total of 40 cores (939 core segments) and 198 Ponar surface grab samples were collected from the five Great Lakes between 2010 and 2014. Median concentrations in Ponar grab samples were 8.4, 0.27, 0.05, 0.19 and 0.01 ng/g dry weight (dw) for total-PCBs, ∑ 7 PCDDs, ∑ 10 PCDFs, ∑ 12 PCNs, and ∑ 7 PCDEs, respectively. By using Geographic Information Systems Analysis with the inverse distance weight (IDW) interpretation of the spatial distribution of the chemical inventory at coring sites, total mass loads in the five lakes combined were estimated to be 511, 15.3, 5.3, 20.7 and 2.9 t for total-PCBs, ∑ 7 PCDDs, ∑ 10 PCDFs, ∑ 12 PCNs, and ∑ 7 PCDEs, respectively. Patterns of spatial distributions revealed pollution hotspots and provided evidence for historical local sources. Concentrations of residues in Ponar grabs and inventories at coring sites, when normalized to concentrations of organic carbon, exhibited statistically significantly correlations with latitude and longitude of the sampling sites for all five chemical groups. At most coring sites, concentrations have been decreasing towards the sediment surface. At locations relatively close to known or suspected sources, estimated half-times for all classes of chemicals were approximately 20 years. The declining trends of PCDDs and PCDFs were unclear at some locations, suggesting the presence of currently active emission sources.
PCBs in Lake Superior, 1978-1992: Decreases in Water Concentrations Reflect Loss by Volatilization
Environmental Science & Technology, 1994
Polychlorinated biphenyl (PCB) water concentrations in Lake Superior from 1978 to 1992 have been compiled in order to determine long-term trends. Based on the concentrations of the same 25 PCB congeners from surface water samples collected between 1980 and 1992, CPCBs have decreased with a first-order rate constant of 0.20 y r l . The concentration of CPCBs in 1980 based on 82 congeners was -2.4 ng/L, by 1992 the concentration had decreased to 0.18 ng/L, indicating a loss of -26 500 kg of PCBs from Lake Superior during this 12-yr period. PCB concentrations in dated sediment cores collected in 1986 and 1990 indicate that the sediments have accumulated -4900 kg of PCBs since 1930 when PCB production began in the United States. A mass balance of PCBs in Lake Superior for 1986 predicts that volatilization, not sedimentation, is the dominant loss process of PCBs from the lake. Net volatilization of PCBs from Lake Superior is estimated to be -1900 kg in 1986, while the loss due to burial in the sediments was -110 kg. A congener-specific first-order rate constant model predicts sedimentation to be a minimal loss process in Lake Superior and volatilization to dominate. The pseudo-first-order rate constants for volatilization and sedimentation of CPCB are predicted by the rate constant model to be -0.24 and -0.004 y r l , respectively. The model estimated PCB inputs in 1986 of 500 kg.
Journal of Great Lakes Research, 2002
Relatively high concentrations (up to 98.5 ng/g dry wt) of polychlorinated biphenyls (PCBs) have been found in two cores penetrating fluvial sands east of Lake Ontario. One core was taken from the upper Salmon River reservoir on the Tug Hill Plateau and the other from Rice Creek near the lake at Oswego. In both instances, portions of the cores containing PCBs and other organochlorines (OCs) lack excess radiogenic 210 Pb and 137 Cs, implying depositional ages predating widespread OC commercial production, use, and release. Within each core there is little vertical variation in PCB composition and highly chlorinated congeners dominate the pattern. In addition, the PCB signature is analytically indistinguishable between cores despite collection over 50 km apart. This argues against local sources, and implies deposition and accumulation by processes operating over a substantial area and time period. Transport and introduction of a residual fraction of colloidal-bound PCBs to the sands via tannin-rich riverine waters is proposed. The PCB congener-specific pattern of air samples collected during the spring and summer of 1999 downwind of the lake at two locations (Rice Creek and Sterling) are similar to the sediments and display anomalous concentrations and chlorination with respect to other air sampling localities in the Great Lakes. A link between the residual fraction of PCBs observed in the sediment and air patterns via volatilization from the terrestrial surface is proposed. Elevated PCB concentrations and chlorination in non-radiogenic fluvial sands and air may reflect regional accumulation and weathering processes operating over many decades and/or enhancement of contaminant deposition and partitioning downwind of the lake related to lake-effect precipitation.
Historical Deposition of PCBs and Organochlorine Pesticides to Lake Winnipeg (Canada
Journal of Great Lakes Research, 2000
Two dated sediment cores; one taken from the north basin and one from the south basin of Lake Winnipeg (Manitoba, Canada) were analyzed for PCBs and organochlorine insecticides in order to examine the depositional history of these persistent organic pollutants (POPs). No previous work had been conducted on current or historical deposition of POPs in Lake Winnipeg sediments. Analysis by high resolution gas chromatography-electron capture detection showed elevated PCB concentrations in sediments dated to the late 1960s to early 1970s. Recent PCB fluxes were estimated to be 5 to 11 µg/m 2 /y in Lake Winnipeg sediments, with burdens of 388 and 337 µg/m 2 in the north and south basins, respectively. Loadings in the north basin sediment indicated atmospheric sources; south basin sediment reflected inputs from agricultural, industrial, and urban activities. DDT inventories were 37 and 127 µg/m 2 in the north and south basin cores, respectively. DDD contributed the largest amount to DDT in sediments, corresponding to anaerobic degradation of the parent molecule. Maximum hexachlorocyclohexane (HCH) concentrations were observed in recent slices of both sediment cores and fluxes ranged from 177 to 914 ng/m 2 /y. There was evidence for recent increases in lindane deposition. Subsurface maximum concentrations were observed for total chlordane (ΣCHL), pentachloroanisole (PCA), and total chlorobenzenes (ΣCBz) in the south basin. ΣCHL, PCA, and ΣCBz, however, were present at maximum concentrations in the surface slice in sediment from the north basin.
Historical Changes in Polychlorinated Biphenyls Contaminated Sediments
American Journal of Environmental Sciences, 2012
Problem statement: PCBs contamination continues to pose a health risk to aquatic environments due to their recalcitrance and bioaccumulation. The Sangamo Weston/Twelvemile Creek/Lake Hartwell Superfund Site is an example of such a health risk as a result of PCBs discharged from a former capacitor manufacturing plant. We conducted a study in twelvemile creek (Clemson, SC, USA) to examine the temporal trend of PCB contaminated sediments. Approach: Surface sediments were sampled at four sites in fall 2008 to compare with concentrations measured in past studies. Total PCBs and congener-specific analyses were performed on Gas Chromatography-Electron Capture Detector (GC-ECD). Results: Total PCB concentrations ranged from 0.026-0.18 µg g −1 , which were one order of magnitude lower than levels measured in 1987 (<0.20-10.23 µg g −1). Total PCBs in this study (based on more than 130 congeners) were similar to those observed in 2003-2004 (based on only 20 congeners). PCB congener patterns indicated that PCBs near the source were dominated by lower chlorinated congeners while heavy congeners were persistent further downstream. Conclusion: Physical and biochemical processes such as natural attenuation, mixing/dispersion and PCBs degradation are contributing to the decreasing concentrations after the discharge was eliminated in 1975. The congener pattern shift is likely attributed to a loss via volatilization and export of contaminated sediment from the stream. Burial could be a potential means to prevent resuspension into the water column.