Bioaccumulation of organochlorines in crows from an indian open waste dumping site: evidence for direct transfer of dioxin-like congeners from the contaminated soil

To assess the significance of waste dumping sites as a source of chemical contamination to ecosystems, we analyzed the residue levels of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and other organochlorines in the breast muscle of crows from a dumping site in the south of Chennai city, South India. Crows from the dumping site contained significantly higher total TEQs (60 +/- 27 pg/g lipid wt) than those from the reference sites (26 +/- 18 pg/g lipid wt). Especially, certain dioxin-like coplanar PCB congeners (Co-PCBs), such as CB-77 and CB-105, whose source is commercial PCBs,were significantly higher in crows from the dumping site than those from the reference sites. Profiles of PCDDs/DFs and Co-PCBs in crows from the dumping site were similar to those of soil at the same site, which was confirmed by principal component analysis. Furthermore, significant positive correlations were obtained between the congener-specific bioconcentration factors (BCFs) of PCDDs/DFs estimated from concentrations in crows and soil from the dumping site and the theoretical BCFs calculated from water-particle and lipid-water partitioning coefficients. On the other hand, the estimated BCFs had significant negative correlations with the molecular weight of PCDDs/DFs, indicating that molecular size limits their bioaccumulation. These results suggest that dioxin-like congeners in the soil of the dumping site were transferred directly to the crows through the ingestion of on-site garbage contaminated with soil, rather than through trophic transfer in the ecosystem. The present study provides insight into the ecological impacts of dumping sites.     

Surveillance of dioxins and polychlorinated biphenyls (PCBs) in food commercialized in Barcelona,Spain

This study explored the potential use of seven congeners of polychlorinated biphenyls (PCBs-7) as indicator compounds for the presence of dioxins and PCBs in food samples, as part of the routine surveillance programme of a public health agency. Samples of 24 foodstuffs with high fat content were collected (ten fresh fish, six dairy products, five meat and three eggs). Duplicate analyses were performed. A research laboratory tested samples for seven polychlorinated dibenzo-p-dioxin (PCDDs), ten dibenzofurans (PCDFs) and twelve dioxin-like PCBs, with limits of detection in the range of ng kg^?1 (ppt). The public health services official control laboratory tested samples for PCBs-7, with a limit of quantification of 5 µg kg^?1 (ppb). The research laboratory detected the presence of dioxins and dioxin-like PCBs in all samples; fish samples had the highest levels (0.04–10.3 pg WHO-TEQ g^?1). The public health service official control laboratory detected PCBs-7 only in five samples, which were all fish. Comparing the results in the two laboratories there seems to be an association between the detection of PCB-7 and the presence of higher levels of PCDD/Fs and dioxin-like PCBs. The use of PCB-7 as an indicator compound may be a practical surveillance strategy for those foodstuffs with higher concentrations of dioxin-like congeners.     

Effects of cooking on concentrations of polychlorinated dibenzo-p-dioxins and related compounds in green leafy vegetable 'Komatsuna'.

The effects of ordinary household cooking processes on concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) (dioxins) were investigated in 'komatsuna', a green leafy vegetable popular in Japan. The concentrations of dioxins were compared using isomer-specific analyses of both uncooked and cooked edible parts of the plant. The mean total 2,3,7,8-chlorine substituted PCDD and PCDF concentrations were reduced from 46.53 pg/g and 0.714 pg/g to 8.301 pg/g and 0.210 pg/g by washing with tap water, and further reduced to 6.054 pg/g and 0.148 pg/g by subsequent boiling, respectively. The cooking processes markedly decreased the concentrations of PCDD/Fs, while having little effect on those of dioxin-like PCBs. The mean total concentration as 2,3,7,8-tetraCDD equivalents (TEQ) was reduced from 0.058 pgTEQ/g to 0.026 pgTEQ/g by washing with tap water and further reduced to 0.019 pgTEQ/g by subsequent boiling. These results suggest that ordinary cooking processes provide a means of reducing the level of dioxins in green leafy vegetables.     

Air-surface exchange of polybrominated diphenyl ethers and polychlorinated biphenyls

Air and leaf-litter samples were collected from a rural site in southern Ontario under meteorologically stable conditions in the early spring, prior to bud burst, over a three-day period to measure the simultaneous diurnal variations in polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). PBDEs are used in a wide range of commercial products as flame retardants and are being assessed internationally as potential persistent organic pollutants. Total PBDE concentrations in the air ranged between 88 and 1250 pg m(-3), and were dominated primarily by the lighter congeners PBDEs 17, 28, and 47, and concentrations of total PCBs ranged between 96 and 950 pg m(-3), and were dominated by the lower chlorinated (tri- to tetra-) congeners. Slopes of Clausius-Clapeyron plots indicate that both PCBs and PBDEs are experiencing active air-surface exchange. Fugacities were estimated from concentrations in the air and leaf-litter and suggest near equilibrium conditions. Following the three-day intensive sampling period, 40 air samples were collected at 24-hour intervals in an attempt to evaluate the effect of bud burst on atmospheric concentrations. Total PBDE concentrations in the daily air samples ranged between 10 and 230 pg m(-3), and were dominated by the lighter congeners PBDE 17, 28, and 47, whereas concentrations of total PCBs ranged between 30 and 450 pg m(-3) during this period. It is hypothesized thatthe high PBDE concentrations observed at the beginning of the sampling period are the result of an "early spring pulse" in which PBDEs deposited in the snowpack over the winter are released with snowmelt, resulting in elevated concentrations in the surface and air. Later in the sampling period, following bud burst, PBDE concentrations in air fell to 10 to 20 pg m(-3), possibly due to the high sorption capacity of this freshly emerging foliage compartment.     

Air-water exchange of polychlorinated biphenyls in the Delaware River

The air-water exchange of polychlorinated biphenyls (PCBs) often results in net volatilization, which is thought to be the most important loss process for PCBs in many systems. Previous investigations of the air-water exchange of PCBs have been hampered by difficulties in treatment of the uncertainty in the calculation of air/water fugacity ratios. This work presents a new framework for the treatment of uncertainty, where uncertainty in physical constants is handled differently from random measurement uncertainty associated with random samples, and it further investigates the sorption of PCBs to colloids (dissolved organic carbon). Simultaneous measurements of PCBs in the air and water of five water quality management zones of the Delaware River were taken in 2002 in support of the total maximum daily load (TMDL) process. Gas-phase concentrations of IPCBs ranged from 110 to 1350 pg m(-3), while dissolved water concentrations were between 420 and 1650 pg L(-1). Shallow slopes of log Koc vs. log Kow plots indicated a colloidal contribution to the apparent dissolved-phase concentrations, such that a three-phase partitioning model was applied. Fugacity ratios for individual congeners were calculated under the most conservative assumptions, and their values (log-transformed) were examined via a single-sample T-test to determine whether they were significantly less than 1 at the 95% confidence level. This method demonstrated that air-water exchange resulted in net volatilization in all zones over all cruises for all but seven high molecular weight congeners. Calculated net fluxes ranged from +360 to +3000 ng m(-2) d(-1) for sigma PCBs. The colloidal correction decreased the volatilization flux of sigma PCBs by approximately 30%. The decachlorinated congener (PCB 209), exhibited unusually high concentrations in the suspended solids, especially in the southern portions of the river, indicating that there is a distinct source of PCB 209 in the Delaware River.     

PCBs, PCDD/Fs, and organochlorine pesticides in farmed Atlantic salmon from Maine, eastern Canada, and Norway, and wild salmon from Alaska

Farmed Atlantic salmon (Salmo salar) from Maine and eastern Canada, wild Alaskan Chinook salmon (Oncorhynchus tshawytscha), and organically farmed Norwegian salmon samples were analyzed for the presence of polychlorinated biphenyls (PCBs), dioxin-like PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzo-p-furans (PCDFs), and chlorinated pesticides. PCDD and PCDF congeners were not detected in > 80% of the samples analyzed. Total PCB concentrations (7.2-29.5 ng/g, wet weight, ww) in the farmed salmon were significantly higher than those in the wild Alaskan Chinook samples (3.9-8.1 ng/g, ww). Concentrations of PCBs, WHO PCB TEQs, and chlorinated pesticides varied significantly by region. PCB and WHO PCB TEQ concentrations in farmed salmon from eastern Canada were lower than those reported in samples collected two years earlier, possibly reflecting recent industry efforts to lower contaminant concentrations in feed. Organically farmed Norwegian salmon had the highest concentrations of PCBs (mean: 27 ng/g, ww) and WHO PCB TEQs (2.85 pg/g,ww); their TEQ values are in the higher range of those reported in farmed salmon from around the world. Removal of skin from salmon fillets resulted in highly variable reductions of lipids and contaminants, and in some skin-off samples, contaminant levels were higher, suggesting that skin removal does not protect the consumer from health risks associated with consumption of farmed salmon.     

Comparison of PCDD/F and dl-PCB levels in Turkish foodstuffs: industrial versus rural,local versus supermarket products,and assessment of dietary intake

Polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) and dioxin-like and non-dioxin-like (indicator) polychlorinated biphenyls (PCBs) were monitored in various foodstuffs of animal origin and edible oil samples obtained from two different cities in Turkey both rural and industrial. Total dioxin+dioxin-like PCBs and indicator PCB concentrations of pooled samples ranged 0.20–4.19 pg World Health Organization-Toxic Equivalency (WHO-TEQ)₍₁₉₉₈₎/g fat and 57.2–1710 pg/g fat, respectively. The dominant congeners were 2,3,4,7,8-PeCDF, 1,2,3,7,8-PeCDD, 2,3,7,8-TCDD and PCB126. Dietary intake of dioxin+dioxin-like PCBs and indicator PCBs from fish, dairy products, edible oil, egg and meat was 0.509 pg WHO-TEQ₁₉₉₈/kg bw (body weight)/day and 839 pg/kg bw/day in Afyon and 0.588 pg WHO-TEQ₁₉₉₈/ kg bw/day and 1070 pg/kg bw/day in Kocaeli, respectively. The major contributors to total exposure were dairy products and fish. Despite the unexplained high contamination level in an individual egg sample from Kocaeli, average concentration levels in Turkey, even in industrialized regions, were low compared to reported concentrations in Western Europe. Exposure levels were well below the tolerable daily intake (TDI) of 2 pg WHO-TEQ₁₉₉₈/kg body weight.     

Influence of Asian and Western United States urban areas and fires on the atmospheric transport of polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and fluorotelomer alcohols in the Western United States

Atmospheric measurements of semivolatile organic compounds (SOCs) were made at Mt Bachelor Observatory (MBO), located in Oregon's Cascade Range, to understand the trans-Pacific and regional transport of SOCs from urban areas. High volume air sampling (approximately 644 m3 for 24 h periods) of both the gas and particulate phases was conducted from April 19, 2004 to May 13, 2006 (n = 69); including NASA's INTEX-B campaign in spring 2006 (n = 34 of 69). Air mass back trajectories were calculated and were used to calculate source region impact factors (SRIFs), the percentage of time the sampled air mass resided in a given source region. Particulate-phase polycyclic aromatic hydrocarbon (PAH) concentrations at MBO increased with the percentage of air mass time in Asia and, in conjunction with other data, provided strong evidence that particulate-phase PAHs are emitted from Asia and undergo trans-Pacific atmospheric transport to North America. Gas-phase PAH and fluorotelomer alcohol (FTOH) concentrations significantly increased with the percentage of air mass time in California's urban areas, whereas retene and polychlorinated biphenyl (PCB) concentrations increased with the percentage of air mass time in Oregon and during regional fire events. In addition, sigma(gas-phase) PAH, retene, and levoglucosan concentrations were significantly correlated (p-value < 0.001) with sigma(PCB) concentrations, suggesting that increased atmospheric PCB concentrations were associated with fires due to the volatilization of stored PCBs from soil and vegetation.     

PCBs and OCPs on a East-to-West Transect: The Importance of Major Currents and Net Volatilization for PCBs in the Atlantic Ocean

Air-water exchange gradients of selected polychlorinated biphenyl (PCB) congeners across a large section of the tropical Atlantic suggested net volatilization of PCBs to the atmosphere. Only for the higher chlorinated PCB 153 and hexachlorobenzene (HCB) were gradients near equilibrium detected. The use of passive samplers also enabled the detection of dichlorodiphenyltrichloroethane (DDT) and its transformation products across the tropical Atlantic, indicating net deposition. There were clear differences between the southern and northern hemisphere apparent in terms of atmospheric concentrations: Once the ship moved from the southern into the northern hemisphere air, concentrations of HCB and other organochlorine pesticides increased several-fold. For large swaths of the tropical Atlantic Ocean, neither PCB nor organochlorine pesticide dissolved concentrations varied much longitudinally, probably due to efficient mixing by ocean currents. In selected samples, dissolved concentrations reflected the influence of river plumes and major ocean currents far away from the continents. Dissolved concentrations of PCBs 28, 52, 101, 118, and HCB increased in the Amazon plume and the Gulf Stream. While the Amazon plume flushed only a few kg of PCBs and HCB, the Gulf Stream is potentially delivering tons of PCBs into the North Atlantic annually.     

How do climate fluctuations affect persistent organic pollutant distribution in North America? Evidence from a decade of air monitoring

Interannual variations of persistent organic pollutant (POP) air concentrations from the Great Lakes region and the Arctic during the 1990s are strongly associated with atmospheric low-frequency fluctuations, notably the North Atlantic Oscillation (NAO), the El Ni?o-Southern Oscillation (ENSO), and the Pacific North American (PNA) pattern. This suggests interactions between climate variation and the global distribution of POPs. Atmospheric concentrations of hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and several lighter polychlorinated biphenyls (PCBs) measured around the Great Lakes basin increased during the positive phases of NAO and ENSO in the spring. This implies that anomalous high air temperatures associated with NAO and ENSO enhance volatilization of POPs from reservoirs on the Earth's surface accumulated in the past. These compounds are then available for transport from source regions to more pristine regions such as the Arctic under favorable flow patterns associated with global climate variations.     

Chiral source apportionment of polychlorinated biphenyls to the Hudson River estuary atmosphere and food web

The New York/New Jersey Harbor Estuary is subject to significant contamination of polychlorinated biphenyls (PCBs) from numerous sources, including the historically contaminated Upper Hudson River, stormwater runoff and sewer overflows, and atmospheric deposition from PCBs originating from the surrounding urban area. However, the relative importance of these sources to the estuary's food web is not fully understood. Sources of PCBs to the estuary were apportioned using chiral signatures of PCBs in air, water, total suspended matter, phytoplankton, and sediment. PCBs 91, 95, 136, and 149 were racemic in the atmosphere of the estuary. However, the other phases contained nonracemic PCB 95 and to a lesser extent PCB 149. Thus, the predominant atmospheric source of these congeners is likely unweathered local pollution and not volatilization from the estuary. The similarity in chiral signatures in the other phases is consistent with dynamic contaminant exchange among them. Chiral signatures in the dissolved phase and total suspended matter were correlated with Upper Hudson discharge, suggesting thatthe delivery of nonracemic contaminated sediment from the Upper Hudson, not the atmosphere, controls phytoplankton uptake of some PCBs. Thus, measures to control PCB contamination in the Upper Hudson should be effective in reducing loadings to the estuary's aquatic ecosystem.     

Atmospheric deposition and fluxes of organochlorine pesticides and coplanar polychlorinated biphenyls in aquatic environments of Hong Kong, China

Concentrations of organochlorine (OC) pesticides and coplanar (dioxin-like) polychlorinated biphenyls (PCBs) in bulk deposition were measured at the Mai Po Marshes Nature Reserve (MPMNR) and A Chau, which are both important habitats for waterbirds in Hong Kong. OC pesticides exempted from the Stockholm Convention were present in greater concentrations than those that have been restricted for use in the region. Among the OC pesticides, HCB, sigmaDDTs, and sigmaHCHs were detected. Concentrations of HCB were greater at MPMNR than at A Chau, and this finding suggests short-range transport of this compound, which is different from the other OC pesticides. Several environmental factors including seasonal variations in temperature, particulate matter, and rainfall may influence the flux of OC pesticides. Since sources of HCB often coexist with sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins and furans), the presence of HCB may be a useful surrogate for monitoring airborne dioxins and for understanding their deposition potential. The contribution of atmospheric deposition to the OC pesticide input to the two study sites was small. Concentrations of most OC pesticides in surface waters were greater than would be predicted based on the inputs from atmospheric deposition and sedimentation. The mass balance calculation suggests a net flux of OC pesticides from bottom sediments to the overlying water column.     

Dynamic air-water exchange of polychlorinated biphenyls in the New York-New Jersey Harbor Estuary

Simultaneous measurements of polychlorinated biphenyls (PCBs) in the air and water over Raritan Bay and New York Harbor were taken in July 1998, allowing the first determinations of air-water exchange fluxes for this heavily impacted system. Average gas-phase concentrations of sigmaPCBs were 1.0 ng m(-3) above Raritan Bay and 3.1 ng m(-3) above New York Harbor. A similar gradient was observed for dissolved water concentrations (1.6 and 3.8 ng L(-1), respectively). Shallow slopes of log K(oc) vs log K(ow) plots indicated a colloidal contribution to the dissolved concentrations, and a three-phase partitioning model was therefore applied. PCBs associated with colloids ranged from 6% to 93% for trichloro- to nonachlorobiphenyls, respectively. Air-water gas exchange fluxes of sigmaPCBs exhibited net volatilization for both Raritan Bay at +400 ng m(-2) day(-1) and New York Harbor at +2100 ng m(-2) day(-1). The correction for the colloidal interactions decreased the volatilization flux of sigmaPCBs by about 15%. Net air-water exchange fluxes of PCBs are expected to remain positive throughout the year due to the large water-air fugacity gradient and relatively constant seasonal water concentrations. The volatilization fluxes are approximately 40 times greater than atmospheric deposition of PCBs via both wet and dry particle deposition, suggesting that the estuary acts as a net source of PCBs to the atmosphere year-round.     

Congener-specific survey for polychlorinated biphenlys in sediments of industrialized bays in Korea: regional characteristics and pollution sources

Areas of the Korean coastline with heavy industry and major harbors were investigated for polychlorinated biphenyl (PCB) pollution. This investigation paid attention to variations in the PCB congener patterns for a possible source of contamination. Surface sediments from 49 sites were sampled. Although the occurrence of PCBs in coastal marine environment correlates well with shipping and industrial activities, the contribution from shipping activities is considerable because of its enormous economical importance in Korea. The highest concentrations were found in harbors with heavy ship traffic and ship construction. Principal component analysis (PCA) of congener-specific composition of PCBs revealed distinct regional patterns, especially in a harbor and steel manufacturing area. PCB signatures with enhanced higher chlorinated congeners were typical for harbors with shipping activities and correlated well with commercial formulations that were formerly used in ship painting. Lower chlorinated congeners with up to five chlorines were significantly abundant in steel works zones which differed from harbor zones. This distinction was consistent with the congener patterns in the ambient air and the effluent of the steel works as well as in the nearby surface sediments. This study identified steel manufacturing as a recent and ongoing emission source of PCBs in Korea's coastal zone.     

婴儿配方乳粉中二噁英及其类似物污染分析

目的 了解婴儿配方乳粉中二噁英及其类似物污染水平,为相关研究提供基础数据.方法 采集601份市售婴儿配方乳粉,按照GB 5009.205-2013《食品安全国家标准食品中二噁英及其类似物毒性当量的测定》对17种多氯代苯并二噁英和多氯代苯并呋喃(PCDD/Fs)和12种二噁英样多氯联苯(dl-PCBs)进行测定.结果 P...     

PCB congeners and dechlorination in sediments of Sheboygan River, Wisconsin, determined by matrix factorization

Nine sediment cores were collected from the Sheboygan River Inner Harbor, WI, and analyzed for polychlorinated biphenyl (PCB) congeners. Total PCBs ranged from approximately 0 to 161 mg/g. Positive matrix factorization (PMF) was applied to the PCB data setto 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.     

Polychlorinated biphenyls (PCBs) and their congener-specific accumulation in edible fish from the Gulf of Gdańsk, Baltic Sea.

Concentrations and composition profiles of polychlorinated biphenyls (PCBs) were investigated in composite samples of 10 species of edible fish from the Gulf of Gdańsk, in the southern part of the Baltic Sea, Poland, to understand the status of contamination and possible human exposure risk. Apart from the total PCBs, planar non-ortho (IUPAC nos 77, 126, 169) and mono-ortho (nos 105, 114, 118, 123, 156, 157, 167, 189) chlorobiphenyls were also quantified and their dioxin-like toxicity assessed. The absolute total PCB concentrations in fish ranged from 43 to 490 ng g(-1) wet wt (910-11000 ng g(-1) lipids), while of TCDD TEQs of planar members were from 0.15 to 3.1 pg g(-1) wet wt (8.1-81 pg g(-1) lipids). The penta- and hexa-CBs usually comprised 70-80% of the total PCBs and were followed by hepta-, tetra- and tri-CBs, and for a specific site tri- and tetra-CBs comprised as much as 22%. Among the individual CB congeners, nos 118, 153 (+132) and 138 (+160 +163 +164) were the most abundant, while no. 110 comprised between 6.8 and 9.3% of the total PCBs in some species. Principal component analysis (PCA) was applied to examine the interdependences among CB congeners in the factor space. The PCA model and cluster analyses were further used to examine site- and species-specific differences and similarities of PCB composition, and the results are discussed. An assessed daily intake rate of TCDD TEQ of planar PCBs with the fishmeal of the Gulf of Gdańsk in the 1990s was between 78 and 96 pg per capita or between 1.3 and 1.6 pg kg(-1) body weight.     

Atmospheric concentrations and deposition of polychorinated biphenyls to the Hudson River Estuary

The first estimates of atmospheric deposition fluxes of polychlorinated biphenyls (PCBs) to the Hudson River Estuary are presented. Concentrations of PCBs were measured in air, aerosol, and precipitation at nine sites representing a variety of land-use regimes at regular intervals from October 1997 through May 2001. Highest concentrations in the gas phase were observed at urban sites such as Camden and Jersey City (sigmaPCB concentrations averaged 3250 and 1260 pg m(-3), respectively). In great portions of the state encompassing forested, coastal, and suburban environments, gas-phase sigmaPCB concentrations were essentially the same (averaging 150-220 pg m(-3)). This spatial trend suggests that atmospheric PCBs arise from highly localized, urban sources which influence atmospheric concentrations and deposition fluxes over a distance of a few tens of kilometers. Atmospheric sigmaPCB deposition fluxes (gas absorption + dry particle deposition + wet deposition) ranged from 7.3 to 340 microg m(-2) yr(-1) and increased with proximity to urban areas. While the magnitude of the fluxes increased with urbanization,the relative proportions of wet, dry, and gaseous deposition remained largely constant. Because the Hudson River Estuary is adjacent to urban areas such as Jersey City, it is subject to higher depositional fluxes of PCBs. These depositional fluxes are at least 2-10 times those estimated for the Chesapeake Bay and Lake Michigan. Inputs of PCBs to the Hudson River Estuary from the upper Hudson River and from wastewater treatment plants are 8-18 times atmospheric inputs, and volatilization of PCBs from the estuary exceeds atmospheric deposition of low molecular weight PCBs.     

PCB congeners and dechlorination in sediments of Lake Hartwell, South Carolina, determined from cores collected in 1987 and 1998

Four sediment cores were collected from Lake Hartwell, SC, in 1987 and 1998 and analyzed for polychlorinated biphenyl (PCB) congeners. Total PCBs ranged from -0 to 58 microg/ g. Positive matrix factorization (PMF) was applied to the data sets to determine PCB source profiles. Two factors were determined for each data set. One factor resembled the original estimated PCB mixture of 80% Aroclor 1016 and 20% Aroclor 1254 and the other factor was a dechlorinated version of the mixture. Evidence of a dechlorination plateau is apparent from the PMF loading solutions because the dechlorinated congener profiles do not change from 1987 to 1998, butthe contribution to the profile from the dechlorinated factor increases from 73% (1987) to 87% (1998). PMF source contributions and plots of PCB concentration versus congener for individual samples provide evidence of enhanced dechlorination at high concentrations. After source apportionment an anaerobic dechlorination model was applied to the dechlorinated source profiles to quantify possible dechlorination pathways. It was found that dechlorination process M, extended to target biphenyl rings with up to six chlorines, provided the best fit for an individual process, and M + Q provides the best fit for combined processes, although M + LP also provides a similarfit. Process LP targets the higher chlorinated congeners and appears to dechlorinate PCBs in the sediments initially.     

Seasonal and spatial variation of polychlorinated naphthalenes and non-/mono-ortho-substituted polychlorinated biphenyls in arctic air

Archived extracts of weekly air samples collected at remote arctic monitoring stations at Alert and Tagish, Canada, and Dunai Island, Russia, in 1994-1995 were combined into 4-week composites and analyzed for levels and seasonal trends of polychlorinated naphthalenes (PCNs) and non- and mono-ortho-substituted polychlorinated biphenyls (PCBs). Mean annual sigmaPCN concentrations were 0.69, 0.82, and 0.38 pg/m3 at Alert, Dunai, and Tagish, respectively. PCNs exhibited a seasonal trend at Alert and Dunai, with higher levels occurring during winter when air masses originating over Eurasia influence the high arctic and coincide with the haze period. Episodic, trans-Pacific transport impacted PCN concentrations at Tagish. A seasonal trend was not evident for the non-/mono-o-PCBs. The contrary PCN and non-/mono-o-PCB trends indicate that the sources of these two compound classes to arctic air differ, and that atmospheric transport from source regions has a greater influence on PCN levels than for non-/ mono-o-PCBs. PCNs apparently originating from combustion sources contribute to levels in winter, as indicated by the presence of combustion marker congeners, but evaporative emissions from source regions are likely the dominant source. PCNs contributed 71 and 75% of dioxin toxic equivalents (TEQ) relative to the non-/mono-o-PCBs at Alert and Dunai and 30% at Tagish during the winter months, demonstrating the toxicological importance of PCNs as a compound class relative to PCBs.