Concentrations, Accumulations, and Inventories of Polychlorinated Dibenzo- p -dioxins and Dibenzofurans in Sediments of the Great Lakes (original) (raw)
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Journal of Great Lakes Research, 1998
Concentrations and accumulations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in dated sediment cores from three of the Great Lakes and two remotely located "control lakes" to assess how inputs of the compounds vary currently and historically among the lakes. The current PCDD accumulation rates in the Great Lakes ranged from a low of 0.0075 ng/cm 2 /yr in Lake Superior to a high of 0.22 ng/cm 2 /yr in Lake Ontario. PCDF accumulation rates ranged from a low of 0.00078 ng/cm 2 /yr in Lake Superior to a high of 0.23 ng/cm 2 /yr in Lake Ontario. The relative importance of atmospheric versus non-atmospheric sources of PCDDs and PCDFs to the lakes was estimated by comparing homolog compositions and accumulation rates among cores and homolog-specific accumulation rates to estimates of atmo~pheric deposition. The estimates are that the atmosphere currently provides (a) 100% of PCDD and PCDF to Lake Superior, (b) 100% of PCDD to southern Lake Michigan, 33-50% of PCDD to northern Lake Michigan, but only 5-35% of PCDF to Lake Michigan, and (c) only 5-35% of PCDD and < 5% of PCDF to Lake Ontario. By comparing the sediment homolog compositions to those (~f non-atmospheric sources, likely non-atmospheric sources are suggested.
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.
Environmental Science & Technology, 2006
A total of 199 sediment samples were collected from 16 locations in the five Laurentian Great Lakes, and each was analyzed for 10 congeners of polybrominated diphenyl ethers (PBDEs) as well as selected polychlorinated biphenyls (PCBs). This paper presents a comprehensive analysis on previously published results for individual lakes. The total accumulation of nine tri-to hepta-PBDE congeners (∑ 9 BDEs) in the sediments of all the Great Lakes was estimated to be approximately 5.2 (1.1 tonnes, and that of decabromodiphenyl ether (BDE209) was 92 (13 tonnes, around year 2002. The inventories of ∑ 9 BDEs and major individual PBDE congeners show strong dependence on the latitude of sampling sites, and such dependence is believed to reflect both the influence of urbanization, which shows south-to-north gradient in the region, and the general direction of long-range transport of airborne pollutants in the northern hemisphere. From the 1970s to 2002, the increases in PBDE input flux to the sediments are exponential at all locations, with doubling times (t 2) ranging from 9 to 43 years for ∑ 9 BDEs, and from 7 to >70 year for BDE209. The longer t 2 values found in sediments compared with those in human and fish in the region suggest the slower response of sediment to emissions. The correlations between the concentrations of ∑ 9 BDEs or BDE209 in surface sediments and latitude are strengthened by normalization of the concentrations with sediment contents of the organic matter or organic carbon, but not soot carbon. Multivariate linear regression equations were developed using data obtained with sediment segments deposited after 1950. All the regressions are statistically significant; and the three independent variablessyear of deposition, latitude, and organic matter content of the sedimentssaccount for 73% and 62% of the variations in the concentrations or the fluxes of ∑ 9 BDEs and BDE209, respectively, in the Great Lakes sediments.
Chemosphere, 2007
Archived suspended sediment samples collected over the period 1980-2002 at Niagara-on-the-Lake in the Niagara river were analyzed to assess temporal trends in contaminants associated with historical industrial activities in the watershed (PCDDs/PCDFs, DLPCBs), compared to more modern industrial chemicals (PBDEs). The temporal trends for PCDDs/PCDFs and DLPCBs were generally similar, and showed a general trend toward decreasing concentrations, which was presumably due to implementation of control measures in the Niagara river watershed, including the remediation of hazardous waste facilities. The temporal trend in PBDEs contrasted with those of PCDDs/PCDFs and DLPCBs. Prior to 1988, PBDEs (sum of 16 congeners including deca-BDE) were generally detected at low-ppb concentrations, but showed a trend toward increasing concentrations over the period 1980-1988. After 1988, PBDE concentrations in the Niagara river showed a more rapidly increasing trend to a maximum of approximately 35 ng/g in 1995, with deca-BDE as the predominant congener detected. Samples collected over the period February 2003 to March 2004 at the head and mouth of the Niagara river were also analyzed for PBDEs; in all cases PBDE concentrations were higher at the mouth of the river at the outflow to Lake Ontario, indicating the Niagara river watershed is a source of PBDE contamination to Lake Ontario. However, PBDE concentrations in suspended sediments of the Niagara river were comparable to, or lower than, concentrations in bottom sediments in other industrialized/urbanized areas of the world. Based on these comparisons of global PBDE bottom sediment concentrations, the Niagara river watershed does not appear to be a significant local source of PBDEs to Lake Ontario, and concentrations in suspended sediments appear to be indicative of general PBDE contamination from a contamination of local, regional, and continental sources. Crown
Polychlorinated dibenzo-p-dioxins and dibenzofurans in Niagara River suspended sediments
Chemosphere
Niagara River archived suspended sediments were analyzed for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs) to investigate temporal trends and to assess congener profiles as source indicators. In general, concentrations ranged from 6 to 35pgg(-1) toxic equivalents (TEQs) and 1000-6000pgg(-1) total PCDDs/Fs and reflected a slight decline in the 1980s, but with little apparent change since that time. This temporal trend was consistent with those observed in Lake Ontario environmental compartments. The observed levels generally reflected ambient background levels in the Niagara River; however, three samples were substantially above ambient levels and a fourth sample, while not elevated, had a profile that was distinctly different from those typically observed at Niagara-on-the-Lake at the mouth of the Niagara River. Event-based concentrations ranged from approximately 160-620pgg(-1) TEQs; congener profiles for these samples were consistent with known sou...
Environmental Fate of Polychlorinated Dibenzo- p -dioxins in Lake Enclosures
Canadian Journal of Fisheries and Aquatic Sciences, 1992
The environmental fate of 1,3,6,8-tetra- (T4CDD) and octachlorodibenzo-p-dioxin (O8CDD), two major dioxin congeners emitted into the environment, was studied in large (40 m3) lake enclosures at the Experimental Lakes Area in northwestern Ontario. The polychlorinated dioxins (PCDDs) were added to replicate enclosures as a sediment slurry at a nominal concentration of 58–59 ng∙L−1. Both congeners partitioned/settled rapidly to the surficial sediments where they persisted over the 2 yr of the study. Initially the concentrations of the T4CDD in water were higher than those of O8CDD, but the concentrations of the T4CDD in the water column declined more rapidly than those of O8CDD, with t1/2 of 2.6 ± 0.2 and 4.0 ± 0.3 d, respectively. Approximately 10–15% of the T4CDD and
2006
We propose to investigate the history of air deposition of polybrominated diphenyl ethers (PBDEs) in the Great Lakes by retrieving sedimentary records. The project falls into the EPA's priority area of "air deposition and source characterization monitoring". The significance of this work stems from the following considerations. Although not a group of persistent bioaccumulative toxics (PBTs) particularly specified in EPA's RFP, PBDEs are more environmentally persistent than PCBs due to their higher resistance to various degradations (de Boer et al., 1998). Their high lipophilicity (log Kow = 4.3 to 9.9, compared with 4.5 to 8.0 for PCBs) indicates a strong bioaccumulation potential. Evidence of their toxic, carcinogenic, and hormone-disrupting effects is also mounting rapidly. A review of the current state of knowledge on PBDEs is given by Darnerud, et al. (2001). The Abstracts of the Second International Workshop on Brominated Flame Retardants (BFR, 2001; Betts, 2001) compile the most up-to-date research achievements.
Journal of Geophysical Research, 2004
Polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) compounds are introduced into the water as a result of large-scale storms and sediment resuspension in the southern basin of Lake Michigan. Settling and suspended sediments, as well as air and water samples, were collected in southern Lake Michigan over a 12 month period. Analysis of contaminant fluxes on settling particles shows that approximately 370 kg of PCBs and 110 kg of DDT compounds are resuspended in southern Lake Michigan during a single basin-wide event (January 1999). Examination of contaminant signals indicates strong regional and temporal source-receptor relationships between settling, suspended, and surficial sediments. The settling, suspended, and bottom surficial sediments in the shallow waters of the southern coastal region are enriched in lower molecular weight PCBs. The sediments in the water column and on the lake bottom in the deeper regions are enriched in higher molecular weight PCBs. Furthermore, falling sediments collected in the deeper regions of the lake are enriched in 4,4 0-DDT. The unique contaminant signal in deep water regions is surprising and suggests a source/receptor relationship among the bottom sediments and the sediments suspended and settling above them.