Distribution characteristics and source analysis of dioxins in sediments and mussels from Qingdao coastal sea

Seven of surface sediments, one sediment core and two mussel samples were collected from the Qingdao coastal sea of the western Yellow Sea and analyzed to determine the horizontal distribution, deposition flux, and toxicity equivalency (TEQs) of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The total PCDD/Fs concentrations in the surface sediments ranged between 10.7 and 428 ng kg(-1) dry wt. The horizontal distribution of PCDD/F congeners in the sediments was characterized by elevated concentrations at the locations in the east of Jiaozhou Bay with the highest concentration occurring near the Haibo River mouth. Physical parameters (total organic carbon contents and sediment types) and the current circulation systems in Jiaozhou Bay can be important factors controlling the horizontal distribution pattern of PCDD/Fs in the bay. The influence of the Haibo River as a source of pollution was evidenced by PCDD/F homologue profiles, indicating a contribution from sewage sludge in addition to other possible sources. Records from the sediment core revealed that the total PCDD/Fs in the Qingdao coastal sea were nearly constant since 1951 till 1980s and increased remarkably after 1980s. The total 2,3,7,8-substituted PCDD/Fs and total TEQs of PCDD/Fs on the lipid basis in the mussel sample inside the bay were significantly higher than in the adjacent sediment. The homologue profiles of PCDD/Fs in the mussels were quite different from those of the sediments, characterized by high TCDF (50% of the total PCDD/Fs).     

Nationwide monitoring of atmospheric PCDD/Fs and dioxin-like PCBs in South Korea

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were measured in ambient air samples collected from different parts of South Korea in 2008, and the measured levels were used for assessing the spatial and temporal distribution of atmospheric PCDDFs and DL-PCBs in South Korea. The average concentrations of atmospheric PCDD/Fs and DL-PCBs among the 37 sites were 28 fg I-TEQ m⁻³ (ND ∼ 617) and 1 fg WHO-TEQ m⁻³ (ND ∼ 0.016). Elevated atmospheric levels of PCDD/Fs and DL-PCBs observed at residential/industrial sites and in the north-west of Korea, indicated a potential contribution and impacts of anthropogenic sources of PCDD/Fs and DL-PCBs. These levels were similar or lower than those previously reported in other ambient air surveys. Average concentrations of PCDD/Fs showed small seasonal variations (ANOVA analysis, p = 0.144). The highest concentrations of PCDD/Fs were observed during winter, followed by spring, autumn and summer. Atmospheric PCDD/Fs and DL-PCBs in South Korea rapidly decreased during the last 10 years (1998-2008), demonstrating the efficiency of stricter regulations and the application of best available technologies/best environmental practices at emission sources. Comparison of the congener profiles and principal component analysis showed that current atmospheric PCDD/Fs are mostly influenced by industrial sources and PCBs from old commercial PCB uses. Nationwide POPs monitoring will continue and allows an effective evaluation of the implementation of the Stockholm Convention on POPs.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans in paddy soils and river sediments in Akita, Japan

Paddy soils and sediments from the Yoneshirogawa, Omonogawa, and Koyoshigawa River Basins in Akita were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). The levels and compositions in those samples including soils from non-agricultural areas (non-agricultural soils) were investigated using isomer-specific analysis to determine characteristic sources. The PCDD/PCDF compositions in the samples were compared with respect to possible sources. The PCDD/PCDF concentrations in paddy soils were much higher than those in the non-agricultural soils and much higher than those found in other parts of Japan. Although PCDD/PCDFs were ubiquitous in sediments from river sources to mouths of the respective river basins, those concentrations were much lower than those from paddy soils and non-agricultural soils, and from other parts of Japan. Comparison of PCDD/PCDF homologues and isomer compositions for samples indicated that compositions of paddy soils and sediments, except for those from river sources, had similar characteristics to PCDD/PCDFs originating from impurities in herbicides, 2,4,6-trichlorophenyl 4-nitrophenyl ether (CNP) and pentachlorophenol (PCP), and that compositions of river-source sediments and non-agricultural soils resembled those of atmospheric depositions. Results of statistical analyses suggest that PCDD/PCDF contamination of paddy soils and sediments is attributable mainly to three sources: CNP, PCP, and atmospheric deposition. Results of this study also demonstrate that CNP and PCP are not only important contaminants of local areas of Japan, but that they exist throughout Akita, in northern Japan. We therefore conclude that PCDD/PCDF pollution caused by those compounds has a widespread influence on paddy soils and river sediments in Japan.     

Levels and homologue profiles of PCDD/Fs in sediments along the Swedish coast of the Baltic Sea

Background, aim, and scope  The primary aim of this study was to explore the variations in PCDD/F levels and homologue profiles of Baltic surface sediments by comprehensively analyzing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in samples from a large number of sites, encompassing not only previously known hotspot areas, but also sites near other potential PCDD/F sources, in pristine reference areas (in which there was no industrial activity) and offshore sites. Materials and methods  Surface sediment samples (146 in total) were collected at various points along the Swedish coast and offshore areas. In addition, bulk deposition was sampled, monthly, at a single site in northern Sweden during 1 year. The concentrations of tetra- through octa-substituted CDD/Fs were determined in both matrices. Results  Highly elevated concentrations of PCDD/Fs were found at many sites in coastal areas and concentrations were also slightly elevated in some offshore areas. Homologue profiles varied substantially amongst samples from coastal sites, while those from offshore and other pristine sediments were relatively similar. The offshore sediments showed different profiles from those observed in the deposition samples. Sediment levels of PCDD/Fs were not generally significantly correlated to organic carbon levels, except in some pristine areas. Comparison of data obtained in this and previous studies suggest that both their levels and profiles are similar today to those observed 20 years ago in coastal and offshore areas. The only detected trend is that their levels appear to have decreased slightly in the offshore area of the Bothnian Sea. Discussion  The localization of hotspot areas along the coast, the lack of consensus between PCDD/F profiles of sediments and general background, and their weak correlations with organic carbon suggest that PCDD/Fs in the study area largely originate from local/regional emissions. However, due to complicating factors such as sediment dynamics and land upheaval, it is not possible to conclude whether these pollutants derive from recent emissions or from a combination of recent emissions and re-distribution of previous inputs. Conclusions  The results show that: elevated levels of PCDD/Fs are present in both coastal and offshore areas of the Baltic Sea, the major hotspots are close to the shore, and there are large variations in profiles, indicating that local emissions are (or have been) the major causes of pollution. Recommendations and perspectives  In order to identify other hotspot areas and trace sources, comprehensive analysis of PCDD/Fs in surface sediments is needed in all areas of the Baltic Sea that have not been previously investigated. The high levels of PCDD/Fs observed in surface sediments also indicate a need to elucidate whether they are due mainly to current emissions or a combination of recent pollution and re-distribution of historically deposited pollutants. To do so, better understanding of sediment dynamics and present-day inputs, such as riverine inputs, industrial effluents, and leakage from contaminated soil is required. There are indications that contaminated sediments have a regional impact on fish contamination levels. However, as yet there is no statistically robust evidence linking contaminated sediments with elevated levels in Baltic biota. It should also be noted that the Baltic Sea is being massively invaded by the deep-burrowing polychaete Marenzielleria ssp., whose presence in sediments has been shown to increase water concentrations of hydrophobic pollutants. In awareness of this, it is clear that high levels in sediments cannot be ignored in risk assessments. In order to investigate the emission trends more thoroughly, analysis of PCDD/Fs in offshore sediment cores throughout the Baltic Sea is also recommended. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Dioxin concentrations in sediments of the Baltic Sea--a survey of existing data

Recent survey results for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, dioxins) in Baltic Sea sediments from Finland, Sweden and Denmark were merged with previously published Baltic Sea data. Regional distribution of concentration levels, differences in congener patterns, and temporal changes in sediment profiles were examined. One of the main objectives was to study if any major point sources for different PCDD/F congeners could be identified on a regional scale, based on sediment records. The survey confirmed the impact of chlorophenol production derived highly chlorinated PCDF-congeners on the total toxicity in sediments in the Gulf of Finland near the Kymijoki river estuary. Signatures of other point sources or combined point sources pertinent to specific industry branches or particular production processes (such as pulp bleaching, vinyl chloride production, thermal processes) may be discerned. However, the findings did not support any of the known point sources significantly influencing those congeners that are most abundant in Baltic herring and salmon. Instead, regional distributions in the Baltic Sea indicate that atmospheric deposition may act as a major source for those congeners and especially for 2,3,4,7,8-PeCDF. There were clear indications of declines in levels in sediment in some areas, but generally the levels of highly chlorinated PCDD/Fs on the northern coast of the Gulf of Finland were still high when compared with other areas of the Baltic Sea. Major areas with data gaps cover the south-eastern and eastern coastal regions of the Baltic Proper and the southern Gulf of Finland.     

Occurrence of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls pollution in sediments from the Haihe River and Dagu Drainage River in Tianjin City, China

The pollution status of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in the sediments of Haihe River, which is the most polluted among the seven largest basins in China, Dagu Drainage River flowing through a chemical industry zone, and two other rivers flowing into Bohai Sea in Tianjin City, China were investigated. The concentrations of PCDD/Fs and PCBs in the sediments from the mainstream of Haihe River were 1.3-26pgI-TEQg(-1) dry weight (dw) and 0.07-0.54pgTEQg(-1)dw, respectively. Heavy PCDD/Fs and PCBs pollution, with 1264pgI-TEQg(-1)dw and 21pgTEQg(-1)dw, was found in sediment from Dagu Drainage River. The congener profiles of PCDD/Fs indicated that the principal contamination source was the production of pentachlorophenol (PCP) or PCP-Na in this area. The correlation between PCDD/Fs or PCBs and total organic matter (TOM) showed that PCDD/Fs or PCBs were independent on TOM.     

Atmospheric bulk deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the vicinity of an iron and steel making plant

An IRA-743 resin bulk sampler was validated to monitor long-term bulk deposition of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Six consecutive sampling campaigns (2008-2009) were conducted at four sites around steel complexes in Pohang, South Korea to investigate spatial and seasonal variations of PCDD/F bulk deposition. The bulk deposition within the steel complex showed the highest ∑_4-8PCDD/F (Tetra-Octa) fluxes, ranging from 204 to 608 (mean: 352) pg m⁻² d⁻¹, indicating steel complexes were major sources of PCDD/Fs. The homologue profiles were dominated with lower chlorinated PCDFs. Furthermore, the prevailing winds were confirmed to influence the spatial distribution of PCDD/F deposition. There were apparent seasonal variations of the bulk deposition at each site, and seasonal homologue patterns of PCDD/Fs were clearly observed. According to the passive air sampling, however, no significant seasonal change of ambient air concentrations of PCDD/Fs was observed. Therefore, it was concluded that the seasonal variations of deposition fluxes of PCDD/Fs probably resulted from temperature-dependent gas/particle partitioning.     

Role of black carbon in the distribution of polychlorinated dibenzo-p-dioxins/dibenzofurans in aged field-contaminated soils

Floodplain soils containing elevated levels of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) were collected from several locations along the Tittabawassee River (Michigan, USA). The PCDD/F profiles of these soils exhibited distinct congener patterns consistent with byproducts from either chloralkali manufacturing or chlorophenols productions. Black carbon (BC) particles were isolated for the first time from floodplain soil impacted by PCDD/Fs. Petrographic analysis showed that BC particles, including coal, oxidized coal, metallurgical coke, depositional carbon, coal tar/pitch, cenosphere, and charcoal, comprised approximately 30% by volume of the organic fraction with size range of 250 μm-2000 μm from a typical floodplain soil. The BC particles with anthropogenic origin such as pitch and coke associated with the chloralkali production process served as both the source and subsequent transporter for the highly hydrophobic PCDD/Fs. These anthropogenic BC particles were enriched with high levels of PCDFs, containing approximately 1000-fold the concentration found in the bulk soil. The strong association of PCDD/Fs with anthropogenic BC directly impacts the physicochemical and biological availability thus the risk associated with these hydrophobic organochlorines in soils and sediments.     

Investigating differential binding of polychlorinated dibenzo-p-dioxins/dibenzofurans in soil and soil components using selective supercritical fluid extraction

Supercritical fluid extraction (SFE) with pure carbon dioxide was performed at increasingly strong conditions to investigate differential binding of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in two impacted soils, in their sieved size fractions, and in small (a few mg) samples of industry-related waste products separated from impacted soil. The binding strengths of PCDD/Fs were shown to be different in the two soils, and in their different soil particle size fractions. As might be expected based on surface area considerations, one soil showed the strongest binding in the smallest (<5 μm) sieved fraction. However, the other soil showed the strongest binding in the larger sized fractions, possibly indicating that process-related particles could be controlling PCDD/F binding. Selective SFE of various types of particles including black carbon and charcoal (separated from soil), and from a suspected process anode residue did show different PCDD/F binding behavior ranging from quite weak binding (charcoal) to very strong binding (anode particles). Shifts to the stronger SFE fractions in the soils after activated carbon treatment agreed well with the decreases previously found in the uptake of PCDD/Fs by earthworms, as well as decreases in their freely-dissolved aqueous concentrations in soil/water slurries. These results show that, as previously demonstrated for PAHs and PCBs, selective SFE can be a useful tool to investigate differences in PCDD/F binding behaviors in impacted soils and sediments and their component parts, as well as a rapid tool for estimating the effectiveness of activated carbon treatments on decreasing the bioavailability of PCDD/Fs in soils and sediments.     

Source identification of PCDD/Fs in agricultural soils near to a Chinese MSWI plant through isomer-specific data analysis

Isomer-specific data were investigated in order to identify the sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in agricultural soils, including Fluvo-aquic and paddy soils, in the vicinity of a Chinese municipal solid waste incineration (MSWI) plant. Homologue and isomer profiles of PCDD/Fs in soils were compared with those of potential sources, including combustion sources, i.e., MSWI flue gas and fly ash; and the impurities in agrochemicals, such as the pentachlorophenol (PCP), sodium pentachlorophenate (PCP-Na) and 1,3,5-trichloro-2-(4-nitrophenoxy) benzene (CNP). The results showed that the PCDD/F isomer profiles of combustion sources and agricultural soils were very similar, especially for PCDFs, although their homologue profiles varied, indicating that all the isomers within each homologue behave identically in the air and soil. Moreover, factor analysis of the isomer compositions among 33 soil samples revealed that the contamination of PCDD/Fs in agricultural soils near the MSWI plant were primarily influenced by the combustion sources, followed by the PCP/PCP-Na and CNP sources. This implication is consistent with our previous findings based on chemometric analysis of homologue profiles of soil and flue gas samples, and identifies PCP/PCP-Na as an additional important source of PCDD/Fs in the local area. This makes the similarities and differences of isomer profiles between Fluvo-aquic and paddy soils more explainable. It is, therefore, advisable to use isomer-specific data for PCDD/F source identifications where possible.     

Phytoremediation to increase the degradation of PCBs and PCDD/Fs

Phytoremediation is already regarded as an efficient technique to remove or degrade various pollutants in soils, water and sediments. However, hydrophobic organic molecules such as PAHs, PCBs and PCDD/Fs are much less responsive to bioremediation strategies than, for example, BTEX or LAS. PCDD/Fs and PCBs represent 3 prominent groups of persistent organic pollutants that share common chemical, toxicological and environmental properties. Their widespread presence in the environment may be explained by their chemical and biological stability. This review considers their fate and dissipation mechanisms. It is then possible to identify major sinks and to understand biological activities useful for remediation. Public health and economic priorities lead to the conclusion that alternative techniques to physical treatments are required. This review focuses on particular problems encountered in biodegradation and bioavailability of PCDD/Fs and PCBs. It highlights the potential and limitations of plants and micro-organisms as bioremediation agents and summarises how plants can be used to augment bacterial activity. Phytoremediation is shown to provide some new possibilities in reducing risks associated with dioxins and PCBs.     

A case study of dioxin monitoring in and around an industrial waste incinerator in Korea

Many studies have been conducted that monitor and trace the sources of polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs) by comparing congener patterns of environmental samples with those of possible sources. In this study, we measured PCDD/F concentrations and compared congener patterns of samples of various media found in and around an industrial waste incinerator in Korea, including stack gas, fly ash, bottom ash, ambient air, soil, pine needle, and human blood. We obtained reliable data on the relationship between the PCDD/F distributions in these sources and the environment, and thus found indicators with which to assess the impact of such sources on the surrounding environment. In addition, the difference between the levels of PCDD/Fs in the blood of short-term workers and long-term workers demonstrates that these workers are exposed to the compounds produced by the indicator.     

Polybrominated, polychlorinated and monobromo-polychlorinated dibenzo-p-dioxins/dibenzofurans and dioxin-like polychlorinated biphenyls in marine surface sediments from Hong Kong and Korea

In this study we investigated occurrences and distribution patterns of dioxin-related compounds (DRCs) such as polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), monobromo-polychlorinated dibenzo-p-dioxins/dibenzofurans (MoBPCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in marine surface sediments collected from the coastal waters of Hong Kong and Korea. In most sampling sites, concentrations of PCDDs were the highest, followed by DL-PCBs, PCDFs, PBDFs, PBDDs, MoBPCDDs and MoBPCDFs in this order. Levels of PBDD/Fs were generally 1-2 orders of magnitude lower than chlorinated analogues. Levels of PCDDs are higher than PCDFs in Hong Kong while levels of PBDFs are higher than PBDDs in Korea (p < 0.05). Report of PBDD/Fs and MoBPCDD/Fs in sediments from East Asian countries is novel and original. Environmental levels of PBDD/Fs are supposed to start increasing in accordance with rising production, use and disposal of brominated flame retardants (BFRs) and recycling processes of e-waste in Asian developing countries.     

Patterns and sources of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in surficial sediments of Lakes Erie and Ontario

This study determines spatial trends and congener patterns of 2378-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in surficial sediments of Lakes Erie and Ontario. Sediments are enriched in 2378-PCDFs in Lake Ontario, and the PCDD/F concentrations increased from shallow near-shore sediments towards deep-water depositional zone sediments. In Lake Erie, sediments were dominated by octachlorodibenzo-p-dioxin, and the highest PCDD/F concentrations were observed in the western basin and the southern shoreline of the central basin with a decrease towards the eastern basin and the northern shoreline of the central basin. Principal components analysis revealed that chemical manufacture and disposal of chemical waste along the Niagara River has been a major PCDD/F source to Lake Ontario; while PCDD/Fs in Lake Erie are from multiple sources including industrial sources along the Detroit River, major tributaries along the southern shoreline of the lake, and atmospherically-derived material from the upper lakes and connecting channels.     

Distribution of PCDD/Fs and dioxin-like PCBs in sediment and plants from a contaminated salt marsh (Tejo estuary,Portugal)

Concentrations and profiles of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) were investigated in sediment and plants collected from a salt marsh in the Tejo estuary, Portugal. The highest PCDD/F and dl-PCB concentrations were detected in uncolonized sediments, averaging 325.25?±?57.55 pg g^?1 dry weight (dw) and 8,146.33?±?2,142.14 pg g^?1 dw, respectively. The plants Sarcocornia perennis and Halimione portulacoides growing in PCDD/F and dl-PCB contaminated sediments accumulated contaminants in roots, stems, and leaves. It was observed that PCDD/F and dl-PCB concentrations in roots were significantly lower in comparison with stems and leaves. In general, concentration of ΣPCDD/Fs and Σdl-PCBs in H. portulacoides tissues were found to be twofold higher than those in S. perennis, indicating a difference in the accumulation capability of both species. Furthermore, congener profiles changed between sediments and plant tissues, reflecting a selective accumulation of low chlorinated PCDD/Fs and non-ortho dl-PCBs in plants.     

Polychlorinated dibenzo-p-dioxins/furans and polychlorinated biphenyls in sediments and aquatic organisms from the Taihu Lake, China

Sediments at 16 sites and muscles of four aquatic species collected in Taihu Lake were analyzed for polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) by HRGC/HRMS. The concentrations of total PCDD/Fs, PCBs and WHO-TEQ were 120.1-1315.1pg/gdw, 889.7-29747.8pg/gdw, and 0.83-17.72pgTEQ/gdw, respectively in sediments; and those in muscles were 5.49-35.84pg/gww, 1517.10-27647.98pg/gww, and 0.52-3.83pgTEQ/gww respectively. The concentrations of PCDD/Fs and PCBs in the sediments were decreasing gradually along the water flow. The pollution levels were compared with other studies and the possible sources were discussed.     

Dietary intake of PCDDs, PCDFs and dioxin-like PCBs, due to the consumption of various marine organisms from Korea

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) residues were measured in 70 marine organisms (40 species) from Korean coastal waters. The PCDD/Fs residues in the organisms varied from 0.02 to 4.39 pg WHO-TEQ/g wet weight and the DL-PCBs residues varied from 0.008 to 6.0 pg WHO-TEQ/g wet weight. The levels in fish from Korean coastal waters were comparable to those found in other countries. Comparing organism groups, the highest PCDD/Fs and DL-PCBs residues were recorded in crustaceans, followed by fish, cephalopods, bivalves and gastropods. Although the congener distributions of PCDD/Fs and DL-PCBs in the organism groups were different, the dominant contributors to the total TEQ concentrations in all groups were 2,3,4,7,8-pentachlorinated dibenzofuran (PeCDF), 1,2,3,7,8-pentachlorinated dibenzo-p-dioxin (PeCDD) and PCB 126. The dietary intake of PCDD/Fs and DL-PCBs from the consumption of marine organisms in Korea was estimated to be 0.68 pg WHO-TEQ/kg bodyweight/day. The contribution of DL-PCBs to the total dietary intake from all organisms groups averaged 60%. The relative contribution of each organism group to the total dietary intake was, in descending order: fish, crustaceans, cephalopods, bivalves and gastropods. The current dietary intake was lower than those in countries with a similar dietary pattern to Korea, but higher than those in countries with smaller quantities of seafood consumption.     

Polychlorinated biphenyls in sediments of the Venice Lagoon

Twenty-four surficial sediment samples, representing different environments within the Venice Lagoon, were analyzed for polychlorinated biphenyls (PCBs) in order to assess degrees of pollution, sources, areal distribution, and potential risk for the environment. Concentrations in surficial sediments range from 2 to more than 2049 microg kg(-1) dw. The maximum is probably due to the discharge of industrial wastes into the Brentella Canal, within the first Industrial Area. Lagoon samples are 11-205 times less contaminated, being influenced by pollutants stored in the canals only occasionally. Congener profiles distinguish PCBs in two main categories. The baseline pollution is probably due to a variety of sources within the lagoon system, whereas less chlorinated PCBs were discharged into the Brentella Canal. Our estimates suggest that, due to high concentrations, toxic equivalents (TEQs) of PCBs are comparable to those relative to PCDD/Fs for the least contaminated samples, whereas they are lower in case of heavy PCDD/F contamination.     

Assessment of variations in atmospheric PCDD/Fs by Asian dust in Southeastern Korea

Atmospheric concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were measured in southeastern Korea during the spring of 2002. During this period, severe Asian dust events (ADs) occurred throughout Korea. Total suspended particulates (TSP) of ADs (456.8 μg m⁻³) increased approximately 3.6-fold compared with non-Asian dust events (NADs; 128.5 μg m⁻³). However, the concentrations of PCDD/Fs (average concentration, 3.34 pg m⁻³) did not increase as much as TSP; there was not a significant difference in the concentrations of particle-bound PCDD/Fs collected between ADs (2.45 pg m⁻³) and NADs (2.05 pg m⁻³). Meanwhile, according to TSP levels, the concentrations during NADs were 2.8-fold higher than ADs (16.73 and 5.98 ng g⁻¹-TSP, respectively). High TSP levels during sand storms without an increase in PCDD/Fs reflected an increase in coarse and accumulation mode particles. Gas/particle partitioning studies revealed the additional inputs of particulate matters to the air during ADs which did not relate with the increase of PCDD/Fs. Furthermore, emissions from ADs may consist of relatively complex atmospheric particles; back trajectories showed air masses moving at low altitudes over Korea, but there were no differences in PCDD/Fs or atmospheric pollutants regardless of air movements. The study area, which is located in southeastern Korea, might be affected by both marine and regional anthropogenic sources, which do not appear to cause clear differences in PCDD/F concentrations or congener profiles between different air trajectories.     

Relationship of PCDD/Fs congener profiles between beef and raw milk in South Korea

The relationship between profiles of residual PCDD/Fs in beef and raw milk was examined by measuring concentrations and detected frequencies. Unrelated samples of beef and raw milk were collected from nine regions in South Korea. Congener-specific profiles of PCDD/Fs in beef and raw milk were very similar. PCDFs, particularly 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, and 2,3,4,6,7,8-HxCDF, were dominant congeners in both beef and raw milk suggesting that sources of contamination may not significantly differ nationwide. The profiles of PCDD/Fs in domestic beef and raw milk in this study were closer to the profiles of emission from metal industries although Korea imports over 75% of feedingstuffs. The ratios of PCDF/PCDD in TEQ concentration were more than 5 and 15 in beef and raw milk, respectively. The mean concentrations of PCDD/Fs in 60 samples of beef and 60 samples of raw milk were 0.80 pg WHO-TEQ/g fat and 0.65 pg WHO-TEQ/g fat, respectively. The residual profiles of PCDD/Fs in raw milk resembled that in beef although the congener profiles might change throughout the food chain. This indicated that monitoring of dioxins in milk could provide information for contamination of milk itself or other associated food.