PCDD/F, PAH and heavy metals in the sewage sludge from six wastewater treatment plants in Beijing, China

In order to better understand land application of sewage sludge, the characterization of heavy metals, PCDD/F and PAHs in sewage sludge was investigated from six different wastewater treatment plants (WWTP) in Beijing City, China. It was found that the total concentrations of Zn in Wujiacun (WJC) sewage sludge, and Cd and Hg in sewage sludge generated from all of the six different places are higher than Chinese regulation limit of pollutants for sludge to be used for agriculture (GB18918-2002). The levels of 16 PAHs that have been categorized as priority pollutants by US EPA in the sewage sludge samples varied from 2467 to 25923 microg/kg (dry weight), the highest values of 25923 microg/kg being found in WJC WWTP. The concentrations of Benzo[a]pyrene were as high as 6.1mg/kg dry weight in WJC sewage sludge, exceeding the maximum permitted content by GB18918-2002. Individual PAH content varies considerably with sewage samples. The ratios of anthracene to anthracene plus phenanthrene (An/178), benz[a]anthracene to benz[a]anthracene plus chrysene (BaA/228), indene[1,2,3-cd]pyrene to indene[1,2,3-cd]pyrene plus benzo[g,h,i]perylene (In/In+BP), and fluoranthene to fluoranthene plus pyrene (Fl/Fl+Py) suggest that petroleum and combustion of fossil fuel were the dominant contributions for the PAHs in sewage sludge. The concentrations of total PCDD/F in the sewage sludge ranged from 330 to 4245 pg/g d.w. The toxicity equivalent concentrations is between 3.47-88.24 pg I-TEQ according to NATO/CCMS, which is below Chinese legislation limit value proposed for land application. The PCDD/F congener/homologue profiles found in the Beijing samples indicated that the high chlorinated PCDD/F contamination might originate mainly from PCP-related source and depositional sources while the low chlorinated PCDD/F homologues could be originating from incineration or coal combustion. The major source of PCDD/Fs in Beijing sludge is still unclear.     

A comparison of TEQ contributions from PCDDs,PCDFs and dioxin-like PCBs in sewage sludges from Catalonia,Spain

Eight sewage sludges from rural, urban and industrial wastewater treatment plants (WWTPs) in Catalonia (Spain) were analysed for polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) to determine the present levels of contamination. A method based on an automated cleanup system followed by an isotope-dilution high-resolution mass spectrometric analysis was employed. Total toxicity equivalent (WHO-TEQ) values were calculated using the toxicity equivalent factors (WHO-TEFs) proposed by WHO for dioxin-like PCBs, PCDDs and PCDFs. The WHO-TEQ(PCDD/F) values for these samples ranged from 4.9 to 20.8 pg/g dry weight (d.w.), with a mean value of 9.3 pg/g d.w., whereas WHO-TEQ(PCB) levels ranged between 1.9 and 6.6 pg/g d.w., with a mean value of 4.2 pg/g d.w. The WHO-TEQ(PCB) contribution varied from 13% to 50%, suggesting that PCB contribution on the toxicity of the samples must be taken into account. Moreover, these contemporary PCDD, PCDF and PCB concentrations were compared with previous data obtained from sewage sludge samples collected during the 80s. Our findings show that contemporary PCDD, PCDF and PCB levels have declined since the 80s.     

Source identification of PCDD/Fs in a sewage treatment plant of a German village

The PCDD/F levels in the sewage sludge of a village in North-East Germany were substantially above the limit of 100 pg I-TEq/g for sludge applied to land. A study was initiated to identify the PCDD/F sources in the sewage of this treatment plant. It was found that the PCDD/F contamination entered the plant through the faecal inlet, where the content of faecal storage tanks was emptied into the treatment plant. The isomeric patterns of the higher chlorinated homologues were similar to that of PCP, while incineration showed some influence on the lower chlorinated homologues. Cluster analysis revealed a profile similar to that of PCP.     

Monitoring of polychlorinated dibenzo-p-dioxins and dibenzofurans, dioxin-like PCBs and polycyclic aromatic hydrocarbons in food and feed samples from Ismailia city, Egypt

Concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyl (PCBs) and polycyclic aromatic hydrocarbons (PAHs) have been determined using GC/HRMS in food (butter, seafood and meat) and feed samples (chicken, cattle and fish) purchased from Ismailia city, Egypt. PCDD/F concentrations in food samples ranged between 0.12 and 3.35 pg WHO TEQ/g wet w, while those in feed samples were between 0.08 and 0.2 pg WHO TEQ/g dry w. Levels of PCB TEQ ranged from 0.14 to 3.2 pg/g wet w in the food samples. The feed samples have an average of 0.35 pg PCB TEQ /g dry w. In this study, butter samples showed the highest contamination levels of PCDD/Fs and PCBs. The PCBs contribution to the total TEQ was on average 63% in seafood and on average 49% for meat and butter. The highest contamination levels of PCDD/Fs and PCBs were found in butter samples. The butter TEQ content is several times higher than that reported in all EU countries and exceeded the EU limits, while the PCDD/F levels in seafood and the feed samples is far below the current EU limit. Generally, congener profiles in the food samples reflect the non-industrialized nature of the city and suggest solid waste burning as a significant source of emission. Nevertheless, the profiles for butter suggest an impact from various sources. In the case of the sum of 16 PAH contamination levels in food samples were in the range of 11.7-154.3 ng/g wet w and feed samples had a range of 116-393 ng/g dry w. Benzo(a)pyrene (BaP) has been detected in the range of 0.05-3.29 ng/g wet w in the food samples; butter showed the highest contamination which exceeded the EU standard set for fats and oil. Fingerprints of PAHs suggested both petrogenic and pyrolytic sources of contamination.     

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.     

Survey of PCDD/Fs and non-ortho PCBs in UK sewage sludges

A survey of PCDD/F and non-ortho PCB concentrations in the mesophilic, anaerobically digested sludge of 14 UK wastewater treatment works was carried out. The range of total Cl1-Cl8DD/F concentrations in the sludges was 8880-428000 pg/g dw with a median of 23300 pg/g dw. The concentrations of the three non-ortho PCBs were in the range 272-63000 pg/g dw with a median of 695 pg/g dw. The PCDD/F I-TEQs of the sludges studied were comparable to those published in the literature with a range of 20-225 pg I-TEQ/g dw and a median of 40.4 pg/g dw. The non-ortho PCBs usually added 2-7 pg/g to the total TEQ with one notable exception which increased the TEQ value 20-fold. With three exceptions, the PCDD/F content of the sludges fell well below the draft EU limit values proposed on 27 April 2000. The homologue group pattern of the PCDD/Fs is dominated by the HpCDDs and OCDD and is consistent with that found in most sewage sludges. There appears to be no correlation between the degree of industrial input and the PCDD/F concentration. This suggests that trade effluent is not always the most significant source of PCDD/Fs to wastewater in the UK.     

Dioxins and furans formation in pilot incineration tests of sewage sludge spiked with organic chlorine

The factors affecting polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) formation were studied in sewage sludge incineration tests carried out on a demonstrative plant. The plant includes a circulating fluidised bed furnace (FBF) and a rotary kiln furnace (RKF), operating alternatively. During the tests sewage sludge was spiked with chlorinated hydrocarbons and the operating parameters of the afterburning chamber were varied. PCDD/F were sampled in each test before the bag filter, thus collecting the above contaminants before abatement systems. From the tests it appeared that PCDD/F were always produced in more abundance in the tests carried out by FBF than by RKF. The higher PCDD/F concentrations in the tests by FBF were reached when sewage sludge was spiked with a high dosage of a surrogate organic mixture of chlorinated hydrocarbons and when the afterburning chamber was used only as transit equipment with the burner off. The distribution of the different PCDD/F homologues was compared. P5CDFs were generally the prevalent fraction, with very few exceptions for the tests by RKF at high temperature of the afterburning chamber. As for FBF tests, it was found that the PCDD/F homologue profile depends on the afterburning chamber temperature.     

Improvements to the UK PCDD/F and PCB atmospheric emission inventory following an emissions measurement programme

PCDD/F data are presented from 75 samples of primary emissions sampled between 1995-97 as part of the compliance monitoring survey undertaken by the UK Environment Agency. Municipal solid waste (MSW), chemical waste and clinical waste incinerators, cement kilns, sinter plants and sewage sludge incinerators were the source categories monitored and reported here. Based on this monitoring programme, the previous national UK emission estimates by Eduljee and Dyke (1) of 560-1100 g I-TEQ a(-1) for 1993 have been revised downwards to 220-660 g I-TEQ a(-1). Despite source reduction measures, MSW incinerators remain a significant source of PCDD/Fs to the atmosphere, contributing between 30-50% of the EPCDD/F I-TEQ emission, rather than the approximately 80% they were estimated to contribute in 1993. 2,3,7,8-substituted PCDD/F congener profile data are presented for some of the source categories and generally support the view that differences in the mixtures ('fingerprints') of PCDD/Fs emitted from different sources are observed. New data on the dioxin-like PCB emissions are presented for cement kilns and sinter plants. These show that TEQ-rated PCBs can make an important contribution to the I-TEQ emitted from certain combustion sources. High concentrations of a full range of PCB congeners/homologues have been measured in the atmosphere close to sintering strands, although the precise source of PCBs from this process remains unclear.     

Correlation between PCDD/F, PCB and PCBz in coal/waste combustion. Influence of various inhibitors

In the flue gas of co-combustion of solid waste and coal in a laboratory scale furnace high concentrations of polychlorinated dibenzo-p-dioxin and furans (PCDD/F), polychlorinated biphenyls (PCB) and polychlorinated benzenes (PCBz) have been detected. These toxic emissions have been reduced by the help of various inhibitors added to fuel before incineration. Knowledge of the congener pattern and homologue profiles of PCDD/F, PCB and PCBz is important to elaborate the mechanism of formation and inhibition of the toxic compounds formed during co-combustion of solid waste and coal. Principle component analysis (PCA) is used in order to find the similarity between the samples and separate them according their toxicity. By the help of the component analysis (CA) the best correlated congeners are effectively detected. Using linear regression between the independent variables and the indicator parameters various good correlated pairs between PCDD/F, PCB and PCBz have been elaborated. Generally it was found that the samples with higher toxicity show a good correlation between tetra- and pentachlorinated benzenes and tetra- and pentachlorinated dibenzo-p-furans. The best indicator parameter for PCDD/F World Health Organization toxic equivalent (WHO-TEQ) among the PCBz congeners investigated is 1,2,4,5-TCBz. This isomer is also significantly correlated with PCDD/F WHO-TEQ and with the sum of PCDD/F WHO-TEQ and PCB WHO-TEQ. However for samples with higher percentage of inhibitors the above mentioned relationship between the surrogate and WHO-TEQ disappeared. The PCB homologues and congeners show no correlation with PCBz and PCDD/F homologues and congeners.     

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).     

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.     

Quantification of PCDD/F concentrations in animal manure and comparison of the effects of the application of cattle manure and sewage sludge to agricultural land on human exposure to PCDD/Fs

PCDD/Fs were quantified in samples of cattle, pig, sheep and chicken manure. TEQs ranged from 0.19 ng TEQ/kg dw for the pig manure to 20 ng TEQ/kg dw for one cattle manure sample. Exposure assessments were carried out to compare the effect of various sewage sludge and cattle manure land application scenarios on human PCDD/F exposure. Background exposure was estimated at 4.9 pg TEQ/kg bw/day and it was found that land application of sewage sludge and cattle manure at contemporary rates did not increase PCDD/F TEQ background exposure. It was concluded that the application of sewage sludge, under the new UK guidelines, and cattle manure to agricultural land, do not make a significant contribution to human exposure to PCDD/Fs.     

Historical trends of PCDD/Fs and dioxin-like PCBs in sediments buried in a reservoir in Northern Taiwan

Polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF) and polychlorinated biphenyl (PCB) concentrations were analyzed at 1-2cm intervals in a sediment core collected from a reservoir in Northern Taiwan to evaluate the organic pollution history. The highest PCDD/F (14.4ng TEQ/kg d.w.) and PCB (0.261ng TEQ(WHO)/kg d.w.) concentrations were determined at 13-15cm (estimated year: 1992). The ages of the levels of sediment core were estimated from the sedimentation rate. Analysis results demonstrate that the PCDD/F concentration of the sediment core measured in the reservoir reached their peak when the municipal waste incinerators (MWIs) in the area started to operate. Furthermore, the decrease in sediment core PCDD/F concentration is related to the time of enforcement of the PCDD/F emission limit set by the Environmental Protection Administration (EPA) in Taiwan. Significant distribution of OCDD in homologue profiles was noted in archived soil samples in Taiwan in which the major input of PCDD/Fs was thought to be atmospheric. Major PCB congeners found in the sediment core were the major components of the commercial PCB products. Input fluxes of PCDD/Fs (5.75-158ng-I-TEQ/m(2)-yr) and PCBs (0.248-3.71ng TEQ(WHO)/m(2)yr) into the reservoir of interest are also calculated from the concentration and sedimentation rate of the sediment. The results reveal that considerable amounts of PCDD/Fs and PCBs were carried into the reservoir of interest in the flood stage but not during normal stage.     

Interlaboratory comparison exercise for the analysis of PCDD/Fs in samples of digested sewage sludge

Five UK laboratories participated in a study designed to explore the principal sources of interlaboratory variation in the analysis of PCDD/Fs in sewage sludge. Samples of wet sludge, dry sludge, toluene extract of sludge and cleaned extract of sludge were prepared by an organising laboratory. The samples were analysed in duplicate by each laboratory along with a solution of PCDD/F standards and reference sediment. Mean coefficients of variation between laboratories were 45% for the wet sludge, 33% for the dry sludge, 32% for the extract of sludge, 36% for the cleaned extract of sludge, 32% for the reference sediment and 28% for the standard solution. The results were subjected to statistical analysis, which showed that there was no specific part of the analysis that introduced a dominant part of the variation. The spread of data generated from the analysis of wet sludge samples was not appreciably greater than the spread for the analysis of cleaned extracts. Thus the drying, extraction and clean up processes in the PCDD/F analysis of wet sludge did not have a dramatic effect on the interlaboratory variation.     

A preliminary investigation of the environmental impact of a thermal power plant in relation to PCB contamination

Purpose

The most significant application of polychlorinated biphenyls (PCBs) is in transformers and capacitors. Therefore, power plants are important suspected sources for entry of PCBs into the environment. In this context, the levels and distribution of PCBs in sediment, soil, ash, and sludge samples were investigated around Seyitömer thermal power plant, Kütahya, Turkey. Moreover, identity and contribution of PCB mixtures were predicted using the chemical mass balance (CMB) receptor model.

Methods

United States Environmental Protection Agency methods were applied during sample preparation, extraction (3540C), cleanup (3660B, 3665A, 3630C), and analysis (8082A).

Results

ΣPCB concentrations in the region ranged from not detected to 385 ng/g dry weight, with relatively higher contamination in sediments in comparison to soil, sludge, and ash samples collected from around the power plant. Congener profiles of the sediment and soil samples show penta-, hexa-, and hepta-chlorobiphenyls as the major homolog groups. The results from the CMB model indicate that PCB contamination is largely due to Clophen A60/A40 and Aroclor 1254/1254(late)/1260 release into the sediment and sludge samples around the thermal power plant.

Conclusions

Since there are no other sources of PCBs in the region and the identity of PCB sources estimated by the CMB model mirrors PCB mixtures contained in transformers formerly used in the plant, the environmental contamination observed especially in sediments is attributed to the power plant. Release of PCBs over time, as indicated by the significant concentrations observed even in surface samples, emphasizes the importance of the need for better environmental management.

     

Changes to the TEF schemes can have significant impacts on regulation and management of PCDD/F and PCB

The changes recommended by the World Health Organisation (WHO) to the toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) and the recommendation to extend both the TEF scheme and the tolerable daily intake (TDI) to include "dioxin-like" PCB congeners have significant implications for regulators who have relied heavily on the International TEF (I-TEF) scheme in setting and monitoring limits and exposure to these compounds. This paper examines example data sets of sources, environmental concentrations, food and exposure to indicate likely changes in calculated toxic equivalent (TEQ) due to the recommended changes to TEFs. Many published data sets available do not provide congener specific data for PCDD/F which limits the ability to recalculate TEQs. There are even fewer congener specific data published to enable calculation of TEQs for the dioxin-like PCBs. In general TEQs calculated using the WHO scheme for emissions to air were found to show small increases (in the order of 1-10%) in comparison to the I-TEQ (for PCDD/F), some sludge samples showed substantial decreases (up to 70%). Levels in food and calculations of exposure showed that the change to TEFs for PCDD/F increased calculated exposure by 10-20% while the change to PCB TEFs decreased calculated TEQ attributable to PCB by 0-10%. The effects of including PCB in the overall TEQ and the changes to TEFs for PCDD/F substantially increase calculated TEQ exposure. Congener specific data should be presented to allow calculation of desired TEQ and the impact of the changes on emission limits, regulations on sludge use and environmental quality standards should all be carefully considered. The absence of data on emissions of dioxin-like PCB means that it is not possible to estimate with any certainty the impact on overall TEQ emissions of including the nominated PCB. Given the potential for confusion with the proliferation of TEFs and the extension to include both PCDD/F and PCB in the calculation of TEQs it is important that great care is taken to clearly express which compounds are included and which TEF scheme has been applied in each case.     

A study on PCB, PCDD/PCDF industrial contamination in a mixed urban-agricultural area significantly affecting the food chain and the human exposure. Part I: soil and feed

This study deals with a PCB, PCDD and PCDF contamination in Brescia, a city in the North-West of Italy, affecting an area with about 11000 inhabitants. The area is close to an industrial plant that produced, in total, some 31,000 ton of PCB. A relevant part of the polluted area is agricultural soil, where cattle were fed with polluted forage and farmers were consuming their own products, so that contamination led eventually to human exposure. Total levels of PCDD/Fs varied from 8 to 592 pgTE(WHO)/g for soil samples and when the dioxin-like PCBs (dl-PCBs) are included, the levels varied from 14.6 to 1033.7 pgTE(WHO)/g. In several cases, the legal limit was exceeded by more than one order of magnitude, with the highest contamination in some agricultural areas and in the surrounding zones. For the forage samples, total levels of PCDD/Fs varied from 0.29 to 2.04 pgTE(WHO)/g and, when dl-PCBs are included, this range increased from 2.04 to 4.75 pgTE(WHO)/g. PCB contamination of the forage through vapor condensation seemed to be relevant. The toxic contribution of dl-PCBs is always relevant and must be considered for risk management. The main component of the contamination source is probably a heavy PCB mixture, such as Aroclor 1262. The study dealt generally with the contamination transfer of PCBs, PCDDs and PCDFs from soil up to humans across the food chain. Results on soils and forages are shown, while measurements concerning the contamination of the animals fed with contaminated forage, and the exposure of the farmers (through human serum analyses), as compared to general population, will be reported in a dedicated paper.     

PCDD/Fs and PCBs in ambient air in a highly industrialized city in Northern Italy

Ambient air samples were collected in five locations around a polychlorobiphenyl (PCB) production plant in a highly industrialized city in the north of Italy, for the analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and PCBs.PCDD/F atmospheric concentrations were lower than those generally detected in urban areas, while PCB concentrations were higher than in urban and industrialized areas in other countries, especially in the locations closest to the plant. To identify source emissions responsible for air pollution we used principal component analysis (PCA) to compare the “fingerprint” of the air in Brescia with some source-related experimental and published data. This analysis showed that the PCDD/F fingerprints were more similar to steel plant emission data, while none of the PCB air patterns were comparable to emission profiles, indicating that different sources are responsible for the concentration of these two pollutants. The highest PCB concentrations detected in the areas closest to the chemical plant are indicative of its impact on the surrounding environment.     

Atmospheric PCDD/F and PCB levels implicated by pine (Cedrus deodara) needles at Dalian, China

Dalian is a seaside city situated in the northeastern monsoon area of China. For the first time, levels of PCDD/F and PCB congeners in pine (Cedrus deodara) needles of Dalian urban areas were investigated. Two sampling campaigns with 17 sampling points were performed in 2002. The summation of tetra- to octachlorinated PCDD/Fs and summation of 209 PCB congeners in Dalian pine needles averaged 127+/-40 ng/kg (dry) and 4389+/-1575 ng/kg (dry), respectively. Average toxic equivalence (TEQ) for PCDD/Fs and PCBs are 2.1 and 0.4 ng/kg (dry), respectively. The pine needles can differentiate spatial variation of the pollutants. The PCDD/F and PCB levels in Dalian pine needles are low or comparable with other international regions that were not impacted by evident point sources. The data can serve as a base for long-term spatial and temporal studies of PCDD/Fs and PCBs in China.     

Resembling a “natural formation pattern” of chlorinated dibenzo-p-dioxins by varying the experimental conditions of hydrothermal carbonization

Until several years ago dioxins were considered as just an unwanted by product of anthropogenic activities and stigmatized as the symbol of man-made environmental pollution. Natural processes, such as forest fires, can emit dioxins, but compared to industrial processes, usually very low quantities are emitted. However after a case of food contamination occurred in the United States of America in 1996 caused by kaolinitic clay a discussion on the provenience started. Besides the relatively high concentration also an unusual PCDD/F distribution pattern was found in these ball clay samples. This specific pattern related to none of the known anthropogenic sources for these contaminants and, in relation to a supposed natural formation, later it was named “natural formation pattern”. Hydrothermal carbonization (HTC) can transform biomass within hours into a brown coal-like product which resembles naturally occurring coal formation. HTC can also transform an already present PCDD/F contamination in a way to obtain a “natural formation pattern” characterized by an unusual high ratio between 1,2,3,7,8,9-HxCDD and 1,2,3,6,7,8-HxCDD and the absence of almost all chlorinated dibenzofurans. By varying the experimental conditions of the HTC process applied to sewage sludge samples contaminated with PCDD/Fs from anthropogenic sources, beside the “natural formation pattern” at a temperatures of 255 °C, a remarkable increase of the toxicity based on WHO–TEQ was observed.