Levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in China and chemometric analysis of potential emission sources

Unexpected Dioxin Formation During Digestion of Soil with Oxidizing Acids

Dioxins, such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), are among the most toxic unintentionally produced persistent organic pollutants, and their emission is of great concern. Herein, we discovered abundant dioxin formation in soil and various organic carbon-containing matrices after digestion with aqua regia. Σ17PCDD/Fs concentrations were in the range of 66.6-142,834 pg/g dw (5.6-17,021 pg WHO2005-TEQ/g dw) in 19 soil samples after digestion with aqua regia for 6 h. Σ17PCDD/Fs concentration was significantly and positively correlated with soil organic carbon content (R2 = 0.89; p < 0.01). Compared with cellulose and lignin, humic acid served as an important organic matter component that was converted to PCDD/Fs during soil digestion. Strong oxidation and production of reactive chlorine by aqua regia may be the key factors in the formation of PCDD/Fs. The yearly emission of PCDD/Fs due to digestion with strong acids by the inspection and testing industry was estimated to be 83.8 g TEQ in China in 2021 based on the highest level, which was ∼0.9% of the total dioxin inventory in China. Great attention should be paid to unexpected dioxin formation during digestion processes considering the potential risk of release from laboratories and enterprises.

The bibliometric analysis and review of dioxin in waste incineration and steel sintering

Facing the common treatment problems of dioxin whose major sources come from waste incineration and steel sintering, we handled a massive literature dataset from the Web of Science database and analyzed the research hotspot and development trend in this field in the past 40 years by bibliometric method. The result indicates that the field of dioxins generated from waste incineration and steel sintering has entered a stage of rapid development since 1990. China occupies a leading position in terms of comprehensive strength with the largest publications output as well as a greater influence in recent years. The most productive institutions and journals are Zhejiang University and Chemosphere, respectively. In addition, the most commonly used keywords in statistical analysis are "fly ash," "emission control," "risk assessment," "congener profile," "formation mechanisms," "sources," "catalysis," and "inhibition," which reflects the current main research direction in this field. The similarities and differences of dioxins generated in waste incineration and steel sintering are reviewed in this paper, which will provide guidance for the future research.

Research on pollution prevention and control BAT of PCDD/Fs in secondary copper industry

Secondary copper industry has received more and more attention due to its high Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) emissions. Best available technologies (BAT) plays an important role in prevention of PCDD/Fs pollution for secondary copper industry and is recommended by the Stockholm Convention on POPs. In this study, AHP-Delphi method-fuzzy comprehensive evaluation method is used to evaluate the 5 smelting technologies that are usually applied in secondary copper industry. The result shows that the Kaldo smelting technology and Ausmelt/ISA smelting technology rank top because of its superior technical performance and good environmental benefits. Then, Kaldo furnace and bag filter were selected as a preliminary validation study on the feasibility of BAT. The results of PCDD/Fs analysis showed that the combination of Kaldo furnace and bag filter can meet the requirements of PCDD/Fs pollution prevention and should be recommended for the treatment of low grades copper scrap.

A comparison of the levels and particle size distribution of lower chlorinated dioxin/furans (mono- to tri-chlorinated homologues) with those of tetra- to octa-chlorinated homologues in atmospheric samples

There is very little information on the levels and particle size distributions of lower chlorinated dibenzo-p-dioxins and dibenzofurans (mono- to tri-CDD/Fs, ΣCl1-3DD/Fs) in the atmosphere, while a number of studies have examined tetra- to octa-chlorinated homologues (ΣCl4-8DD/Fs). In this study, we measured the concentration and particle size distribution of ΣCl1-3DD/Fs in ambient air in suburban Beijing and compared them with that of ΣCl4-8DD/Fs for the first time. The mean concentration of ΣCl1-3DD/Fs was 54.63 pg m(-3), which is about 5.4 times that of ΣCl4-8DD/Fs. The ΣCl1-3DD/Fs accounted for 85% of ΣCl1-8DD/Fs, and MoCDFs made up the largest proportion (43%) of PCDD/F homologues. The ΣCl1-3DD/Fs mainly occurred in the gas phase, while the ΣCl4-8DD/Fs mainly occurred in the particulate phase. The majority of ΣCl1-3DD/Fs (70%) occurred in dae > 1.0 μm particles, which is the reverse of the trend observed for ΣCl4-8DD/Fs, of which 78% occurred in dae < 1.0 μm particles. The observed high concentrations of ΣCl1-3DD/Fs and different distribution patterns demonstrate that it is necessary to consider the lower chlorinated homologues to improve our understanding of the environmental behavior and health risk assessments of PCDD/Fs in the atmosphere.

Distribution of PCDD/Fs in the fly ash and atmospheric air of two typical hazardous waste incinerators in eastern China

Distribution of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in the fly ash and atmospheric air of one medical waste incinerator (MWI) and one industrial hazardous waste incinerator (IHWI) plants were characterized. The PCDD/F concentrations of the stack gas (fly ash) produced from MWI and IHWI were 17.7 and 0.7 ng international toxic equivalent (I-TEQ)/Nm(3) (4.1 and 2.5 ng I-TEQ/g), respectively. For workplace air, the total concentrations of PCDD/Fs were 11.32 and 0.28 pg I-TEQ/Nm(3) (819.5 and 15.3 pg/Nm(3)). We assumed that the large differences of PCDD/F concentrations in workplace air were due to the differences in chlorine content of the waste, combustion conditions, and other contamination sources. With respect to the homologue profiles, the concentrations of PCDFs decreased with the increase of the substituted chlorine number for each site. Among all of the PCDD/F congeners, 2,3,4,7,8-PeCDF was the most important contributor to the I-TEQ value accounting for ca. 43 % of two sites. The gas/particle partition of PCDD/Fs in the atmosphere of the workplace in the MWI was also investigated, indicating that PCDD/Fs were more associated in the particle phase, especially for the higher chlorinated ones. Moreover, the ratio of the I-TEQ values in particle and gas phase of workplace air was 11.0. At last, the relationship between the distribution of PCDD/Fs in the workplace air and that from stack gas and fly ash was also analyzed and discussed. The high correlation coefficient might be a sign for diffuse gas emissions at transient periods of fumes escaping from the incinerator.

Concentrations, atmospheric partitioning, and air-water/soil surface exchange of polychlorinated dibenzo-p-dioxin and dibenzofuran along the upper reaches of the Haihe River basin, North China

Polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF) were overall measured and compared in ambient air, water, soils, and sediments along the upper reaches of the Haihe River of North China, so as to evaluate their concentrations, profiles, and to understand the processes of gas-particle partitioning and air-water/soil exchange. The following results were obtained: (1) The average concentrations (toxic equivalents, TEQs) of 2,3,7,8-PCDD/PCDF in air, water, sediment, and soil samples were 4,855 fg/m(3), 9.5 pg/L, 99.2 pg/g dry weight (dw), and 56.4 pg/g (203 fg TEQ/m(3), 0.46 pg TEQ/L, 2.2 pg TEQ/g dw, and 1.3 pg TEQ/g, respectively), respectively. (2) Although OCDF, 1,2,3,4,6,7,8-HpCDF, OCDD, and 1,2,3,4,6,7,8-HpCDD were the dominant congeners among four environmental sinks, obvious discrepancies of these congener and homologue patterns of PCDD/PCDF were observed still. (3) Significant linear correlations for PCDD/PCDF were observed between the gas-particle partition coefficient (K p) and the subcooled liquid vapor pressure (P L (0)) and octanol-air partition coefficient (K oa). (4) Fugacity fraction values of air-water exchange indicated that most of PCDD/PCDF homologues were dominated by net volatilization from water into air. The low-chlorinated PCDD/PCDF (tetra- to hexa-) presented a strong net volatilization from the soil into air, while high-chlorinated PCDD/PCDF (hepta- to octa-) were mainly close to equilibrium for air-soil exchange.

Occurrence, possible sources, and temporal trends of polychlorinated dibenzo-p-dioxins and dibenzofurans in water and sediment from the lower Yangtze River basin, Jiangsu and Shanghai areas of Eastern China

The concentrations, compositional profiles, and possible sources of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) in water column and surface sediment samples from the lower reaches of the Yangtze River were investigated, and the potential risks posed by these chemicals were evaluated. Concentrations of the 17 2,3,7,8-substituted PCDD/PCDF in the water and sediment samples ranged from 0.45 to 10.0 pg TEQ/L (mean 2.34 pg TEQ/L) and from 0.31 to 51 pg TEQ/g dw (mean 5.25 pg TEQ/g dw), respectively. Water and sediments from the Nanjing-Nantong sections of the Yangtze River were found to have elevated PCDD/PCDF levels, and the PCDD/PCDF TEQ concentrations in 13 sediment samples exceeded the probable effect levels (PEL), above which adverse biological effects are likely. Multivariate statistical analysis indicated that the principal PCDD/PCDF contamination source for the water and sediment was the production and use of pentachlorophenol (PCP) or sodium pentachlorophenate (PCP-Na). PCDD/PCDF concentrations were stable over time near the Yangtze River Estuary but had increased sharply in recent decades in the Nanjing-Nantong section, which will have been related to the growth in industrial activities and other anthropogenic PCDD/PCDF sources. Total organic carbon (TOC) and PCDD/PCDF concentrations correlated significantly (R=0.474, P<0.01), suggesting that TOC plays an important role in the transport and re-distribution of PCDD/PCDF in the Yangtze River basin.

Heavy metals and PCDD/Fs in solid waste incinerator fly ash in Zhejiang province, China: chemical and bio-analytical characterization

Fly ash samples were taken from solid waste incinerators with different feeding waste, furnace type, and air pollution control device in six cities of Zhejiang province. The solid waste incinerators there constitute one fifth of incinerators in China. Heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in the fly ash. Moreover, the fly ash samples were extracted by toxicity characteristic leaching procedure (TCLP). The biotoxicity of the leachate was evaluated by Chlorella pyrenoidosa. High variation and contents were found for both the heavy metals and PCDD/Fs. The contents of Zn, Cu, As, Pb, Cd, Cr, Ni, and Hg in the fly ash samples varied from 300 to 32,100, 62.1-1175, 1.1-57, 61.6-620, 0.4-223, 16.6-4380, 1.2-94.7, and 0.03-1.4 μg g(-1) dw, respectively. The total contents of 17 PCDD/Fs varied from 0.1128 to 127.7939 μg g(-1) dw, and the 2,3,7,8-TeCDD toxic equivalents (TEQ) of PCDD/Fs ranged from 0.009 to 6.177 μg g(-1) dw. PCDF congeners were the main contributor to the TEQ. The leachate of the fly ash showed biotoxicity to C. pyrenoidosa. A significant correlation was found between the Cd and EC(50) values. Further research is required to investigate the environmental impact of the various pollutants in the fly ash.

Estimation and characterization of PCDD/Fs, dl-PCBs, PCNs, HxCBz and PeCBz emissions from magnesium metallurgy facilities in China

Magnesium production is considered to be one potential source of unintentional persistent organic pollutants (unintentional POPs). However, studies on the emissions of unintentional POPs from magnesium metallurgy are still lacking. Emissions of unintentional POPs, such as polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), polychlorinated naphthalenes (PCNs), hexachlorobenzene (HxCBz) and pentachlorobenzene (PeCBz) are covered under the Stockholm Convention. In this study, these emissions were investigated through a magnesium smelting process. Stack gas and fly ash samples from a typical magnesium plant in China were collected and analyzed to estimate the emissions of unintentional POPs from magnesium metallurgy. Emissions factors of 412 ng TEQ t(-1) for PCDD/Fs, 18.6 ng TEQ t(-1) for dl-PCBs, 3329 μg t(-1) for PCNs, 820 μg t(-1) for HxCBz, and 1326 μg t(-1) for PeCBz were obtained in 2009. Annual emissions from magnesium metallurgy in China were estimated to be 0.46 g WHO-TEQ for PCDD/Fs and dl-PCBs, 1651 g for PCNs, 403 g for HxCBz and 653 g for PeCBz, respectively.

Atmospheric concentrations, occurrence and deposition of persistent organic pollutants (POPs) in a Mediterranean coastal site (Etang de Thau, France)

Atmospheric concentrations and deposition fluxes of PCDD/F and PCB have been evaluated over a 1-year period in a Mediterranean coastal lagoon (Etang de Thau, France). Indicative PBDE air concentrations in the hot season are also reported in this work. ∑2,3,7,8-PCDD/Fs and ∑18PCBs (gas+particulate) air concentrations ranged from 67 to 1700 fg m(-3) and from 13 to 95 pg m(-3), respectively whereas ∑8PBDEs (gas+particulate) summer time levels varied from 158 to 230 pg m(-3). The PCDD/F and PCB atmospheric occurrence over Thau lagoon and subsequent inputs to the surface waters are determined by an assemble of factors, being the seasonality of atmospheric concentration, the air mass origin and meteorological conditions important drivers. Total (wet+dry) ∑2,3,7,8-PCDD/Fs and ∑18PCBs deposition fluxes to Thau Lagoon waters are 117 and 715 pg m(-2)d(-1), respectively.

PCDD/Fs atmospheric deposition fluxes and soil contamination close to a municipal solid waste incinerator

Bulk depositions and surface soil were collected in a suburban area, near the Adriatic Sea, in order to assess the contribution of a municipal solid waste incinerator to the area's total contamination with polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDDs and PCDFs). Samples were collected at two sites, situated in the area most affected by plant emissions (according to the results of the Calpuff air dispersion model), and at an external site, considered as a reference. Results show that the studied area is subject to low contamination, as far as these compounds are concerned. Deposition fluxes range from 14.3 pg m(-2)d(-1) to 89.9 pg m(-2)d(-1) (0.75 pg-TEQ m(-2)d(-1) to 3.73 pg-TEQ m(-2)d(-1)) and no significant flow differences are observed among the three monitored sites. Total soil concentration amounts to 93.8 ng kg(-1) d.w. and 1.35 ng-TEQ kg(-1)d.w, on average, and confirms a strong homogeneity in the studied area. Furthermore, from 2006 to 2009, no PCDD/Fs enrichment in the soil was noticed. Comparing the relative congener distributions in environmental samples with those found in stack emissions from the incineration plant, significant differences are observed in the PCDD:PCDF ratio and in the contribution of the most chlorinated congeners. From this study we can conclude that the incineration plant is not the main source of PCDD/Fs in the studied area, which is apparently characterized by a homogeneous and widespread contamination situation, typical of an urban area.

Levels of PCDD/Fs in agricultural soils near two municipal waste incinerators in Shanghai, China

A study was conducted on polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in agricultural soils at 41 sites within a radius of 3 km from two municipal solid waste incinerators in Shanghai. The PCDD/F concentrations ranged from 71.32 to 3,881.44 pg g⁻¹ (0.64-61.15 pg I-TEQ g⁻¹). The highest PCDD/F concentrations were found approximately 1,000 m from the municipal solid waste incinerators. The PCDD/F homologue profiles of all soil samples were compared with the profiles from suspected PCDD/F sources by multivariate statistical analysis. The results showed that, the PCDD/F pollutions in some soil samples can be attributed to emissions from the municipal solid waste incinerators.

Mixed polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans in stack gas emissions from industrial thermal processes

Very little is known about mixed polybrominated/chlorinated dibenzo-p-dioxins and dibenzofurans (PBCDD/F) in industrial thermal processes. In this study, the occurrences and characteristics of PBCDD/F from various incineration and metallurgical processes were investigated. In addition, PBCDD/F analytical protocols based on HRGC/HRMS were developed and optimized. The sum of isomer group concentrations ranged from 1.7-3740 pmol Nm(-3) for PBCDF and 0.2-582 pmol Nm(-3) for PBCDD. For some metallurgical industries, the amounts of PBDD/F and PBCDD/F emitted were similar to or even higher than the amounts of PCDD/F. The sources of bromine and brominated-precursors in these processes should be evaluated. The PBCDD/F characteristics investigated included isomer group patterns, ratio of bromine and chlorine incorporated in PBCDD/F, and ratio of halogenated furans to dioxins. Lower brominated PBCDD/F were binomially distributed. But in some cases, the concentrations of higher brominated PBCDD/F were much higher than predicted from the binomial distribution. The formation mechanisms of PBDD/F, PBCDD/F, and PCDD/F in these processes were also evaluated.

Environmental and human exposure to persistent halogenated compounds derived from e-waste in China

Various classes of persistent halogenated compounds (PHCs) can be released into the environment due to improper handling and disposal of electronic waste (e-waste), which creates severe environmental problems and poses hazards to human health as well. In this review, polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), tetrabromobisphenol A (TBBPA), polybrominated phenols (PBPs), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), and chlorinated polycyclic aromatic hydrocarbons (ClPAHs) are the main target contaminants for examination. As the world's largest importer and recycler of e-waste, China has been under tremendous pressure to deal with this huge e-waste situation. This review assesses the magnitude of the e-waste problems in China based on data obtained from the last several years, during which many significant investigations have been conducted. Comparative analyses of the concentrations of several classes of toxic compounds, in which e-waste recycling sites are compared with reference sites in China, have indicated that improper e-waste handling affects the environment of dismantling sites more than that of control sites. An assessment of the annual mass loadings of PBDEs, PBBs, TBBPA, PBPs, PCDD/Fs, and ClPAHs from e-waste in China has shown that PBDEs are the dominant components of PHCs in e-waste, followed by ClPAHs and PCDD/Fs. The annual loadings of PBDEs, ClPAHs, and PCDD/Fs emission were estimated to range from 76,200 to 182,000, 900 to 2,000 and 3 to 8 kg/year, respectively. However, PCDD/Fs and ClPAHs should not be neglected because they are also primarily released from e-waste recycling processes. Overall, the magnitude of human exposure to these toxics in e-waste sites in China is at the high end of the global range.

PCDD/F, PBDE, and nonylphenol contamination in a semi-enclosed bay (Masan Bay, South Korea) and a Mediterranean lagoon (Thau, France)

Chemical contamination of the coastal marine environment by polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) was assessed along with emerging contaminants such as polybrominated diphenyl ethers (PBDEs) in an industrially well-developed country (France) and a fast-developing country (Korea). Other chemicals, i.e. nonylphenol (NP) and 5 beta(H)-cholestan-3beta-ol (coprostanol) were determined to trace industrial waste and/or domestic inputs. These compounds were analyzed in coastal sediments and mussels in two enclosed coastal water bodies: Masan Bay (South Korea) and Thau lagoon (France). The overall levels of target organic contaminants were higher in Masan Bay than in Thau lagoon. The mean concentrations of 17 PCDD/Fs, 13 PBDEs, NP and coprostanol in Masan Bay sediments were, respectively, 1.3, 11, 248 and 291 ng g(-1) dry weight (d.w.); in Thau lagoon sediments they were, respectively, 0.39, not detectable (nd), 23 and 395 ng g(-1)d.w. Mean concentrations in mussels (coprostanol and cholestanol were not measured) were 0.0093, 13, 140 ng g(-1)d.w. in Masan Bay and 0.016, 0.94, 38 ng g(-1)d.w. in Thau lagoon. Principal component analysis of the contaminants and chemical tracers indicates possible point sources of pollution for Masan Bay and Thau lagoon. This study highlights a growing pollution problem in Asia and in particular a tremendous uptrend in Korea, in comparison to more controlled discharges and releases in Western Europe.

Stack gas emissions of PCDD/Fs from hospital waste incinerators in China

Stack gas samples from 14 domestic-made hospital waste incinerators (HWIs) in China were collected and analyzed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). The waste burning capacities of the investigated HWIs ranged from 5 to 25 ton d(-1). The stack gas emissions of PCDD/Fs from HWIs exhibited a large variation (0.08-31.60 ng I-TEQNm(-3)). Nine incinerators had the emission levels below the current emission standard in China (0.5 ng I-TEQN m(-3)), while only two facilities exhibited emission levels below the European Union directive emission limit (0.1 ng I-TEQN m(-3)). For two plants, concentrations of PCDD/Fs in stack gas were above 10.0 ng I-TEQN m(-3). The emission factors of PCDD/Fs from the investigated HWIs were in the range of 0.78-473.97 microg I-TEQ ton(-1) medical wastes. It was estimated that 4.87 g I-TEQ of PCDD/Fs was annually released from HWIs to the atmosphere in China in 2006. Principal component analysis and hierarchical cluster analysis were applied to analyze the congener profiles of PCDD/Fs from HWIs in China.

A national survey of polychlorinated dioxins, furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in human milk in China

The study examined the levels of dioxin-like compounds in 24 pooled samples that were comprised of 1237 individual human milk samples from 12 provinces of China. The samples were taken in different regions to evaluate the body burden of these contaminants and assess their health risk to breast-feeding infants of China. The pooled samples were analyzed for 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and 12 dioxin-like polychlorinated biphenyls (dl-PCBs) congeners. The population of the provinces involved in this study accounts for approximately 50% of the total Chinese population. The range of upper-bound total-TEQ in samples was from 2.59 pg TEQ g(-1) lipid to 9.92 pg TEQ g(-1) lipid with a mean of 5.42 pg TEQ g(-1) lipid and a median of 5.11 pg TEQ g(-1) lipid. PCDD/Fs-TEQ and total-TEQ in human milk from rural areas were lower than those from urban areas. The positive correlations were found between total-TEQ level in human milk and the consumption of aquatic food and meat respectively. The mean estimated daily intake of PCDD/Fs and dl-PCBs by infants was 28.0 pg TEQ kg(-1) bw per day with a range from 14.2 pg TEQ kg(-1) bw per day to 48.6 pg TEQ kg(-1) bw per day. In the study, both the TEQ body burden of the sample population and estimated daily TEQ intake of breast-feeding infants were lower than those of developed countries. Continuous surveillance on PCDD/Fs and dl-PCBs levels in human milk is needed to correctly evaluate both the environmental impact and human health risk in China.

Estimation and characterization of PCDD/Fs and dioxin-like PCBs from secondary copper and aluminum metallurgies in China

The secondary metallurgy industry is considered as one source of polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs). This study investigated the emission factors and total emissions amounts of PCDD/Fs and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) released from secondary aluminum and copper metallurgy industries in China. The congener patterns are shown and the formation mechanism is also discussed in this paper. The toxic equivalency (TEQ) emission factor of PCDD/Fs is higher for secondary copper production, at 14,802 ng TEQ t(-1) than for secondary aluminum production, at 2650 ng TEQ t(-1). However, the TEQ emission factor of dioxin-like PCBs of secondary aluminum production, with 193 ng TEQ t(-1), is higher than that of secondary copper production with 98.1 ng TEQ t(-1). The total estimated emission amount of PCDD/Fs released to air from the production of 2.75 million tons secondary aluminum and 2 million tons secondary copper in 2007 are 7.3 and 37.5 g TEQ yr(-1), respectively, the corresponding dioxin-like PCBs total emission amounts being 0.53 and 0.2 g TEQ yr(-1) respectively. In general, the emission factors and the total emission amounts of the secondary aluminum and copper metallurgies in China stay in the middle level compared to values reported for other countries. The most abundant congener of PCDD/Fs is 2,3,4,7,8-PeCDF and the most abundant congener of dioxin-like PCBs is CB-126 in samples collected from both secondary aluminum and copper metallurgies. According to the distribution of organochlorocompounds (PCDF>PCDD>PCB, PCDF/PCDD>>1) and the dominant contribution of higher chlorinated congeners, the de novo synthesis is assumed to be the main formation pathway of PCDD/Fs and PCBs in the secondary copper and aluminum metallurgies.

Polychlorinated dibenzo-p-dioxins and dibenzofurans in soils and sediments from Daliao River Basin, China

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) were analyzed in surface sediments and top soils collected from 30 sites in Daliao River Basin. The concentrations of PCDD/F ranged from 0.28 to 29.01 ng TEQ kg(-1) dw (mean value, 7.45 ng TEQ kg(-1)dw) in sediments, and from 0.31 to 53.05 ng TEQ kg(-1)dw (mean value, 7.00 ng TEQ kg(-1)dw) in soils. PCDD/F pollution in sediments from the mid- and downstream sections of Hun River was found to be relatively heavy, and the levels of PCDD/F contamination in paddy soils were generally higher than those of upland soils. Using multivariate statistical analysis, the PCDD/F homologue and congener profiles of all soil and sediment samples were compared with those of suspected PCDD/F sources. The results showed that, PCDD/F contamination in most sediments of Hun River should mainly originated from the production of organochlorine chemicals, while metal smelting was the important potential source of PCDD/F in the drainage area of Taizi River. PCDD/F contamination in paddy soils should be simultaneously attributed to the polluted water irrigation and the organochlorine pesticide application.

Levels of PCDD/Fs and trace elements in superficial soils of Pavia Province (Italy)

Trace elements and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in soils from rural and light-industrialized sites (n = 168) of Province of Pavia (Northern Italy). Most of the trace element values fit in typical ranges of concentrations in soils and are similar to the ones reported for rural sites in Italy or sites with no direct anthropogenic impact. Total concentrations of 2,3,7,8 chlorine substituted PCDD/Fs in superficial soils ranged between 24.4 and 1287 pg g(-1) dw (0.5-28.9 pg WHO98-TEQ g(-1) dw). The North Eastern part of the Province presented significantly higher levels (p < 0.001) than the rest of the Province for As, Cd, Hg, Pb, Zn and PCDD/Fs. While the existence of a defined heavy metal polluting source for this specific site has been suggested, in the case of PCDD/Fs, profiles were not linked to any specific emission source fingerprint. In the whole extension of Pavia Province, OCDD/F dominated the 2,3,7,8 chlorine substituted congener soil pattern, followed by the 1,2,3,4,6,7,8 hepta-CDD/F congener. Principal Component Analysis (PCA) showed that this profile could not be associated to any described PCDD/F emission source fingerprint and was relatively similar to the baseline deposition of sites with no direct impact of PCDD/F emission sources independently of land use.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in marine mussels from French coasts: levels, patterns and temporal trends from 1981 to 2005

The levels and temporal trends of toxic polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in archived marine mussels collected between 1981 and 2005 from selected sites along French coasts. The geographical distribution and levels of PCDD/Fs generally reflect regional inputs of these contaminants: the highest concentrations were determined in samples from the Seine river estuary (English Channel) and Toulon area (Mediterranean coast); the lowest levels were determined in Corsica (Mediterranean Sea). PCDD/F isomeric composition showed a fairly homogeneous distribution pattern throughout the various sampling sites. This pattern, dominated by 2,3,7,8-TCDF and OCDD, can be considered as typical for the study species. However, on a more local scale, some differences in isomeric composition in mussels were identified in relation to local source characteristics. The time trend study showed a pronounced decrease in PCDD/F concentrations over the 24-year period at most sites, except Toulon on the Mediterranean Sea, where the decrease was not significant. This overall decrease probably reflects the general drop in PCDD/F emissions in Europe since 1980. However, high concentrations were determined in mussels collected in recent years (1999, 2001 and 2005) from the mouth of the Seine river. These concentrations are related to particular hydrological conditions, and intensive sediment dredging due to a new port construction at the mouth of the estuary. The results presented in this paper provide reference data on the contamination of shellfish by persistent organic pollutants in the marine environment.