Isotope dilution analysis of polychlorinated biphenyls (PCBs) in transformer oil and global commercial PCB formulations by high resolution gas chromatography-high resolution mass spectrometry

Special polychlorinated biphenyls (PCBs) standards (native and isotope labeled) were analyzed by isotope dilution method using HRGC-HRMS. Multiple analysis of special PCBs standards by three different laboratories produced the relative response factors (RRFs) and relative standard deviations (RSDs %) was in the average of 0.979 and 3.86, respectively. Additionally, inter-laboratory analysis of various forms of transformer oil revealed the PCBs concentrations were in the following order; PCBs fortified transformer oil (940-1300 ng/g)>PCB polluted transformer oil (490-680 ng/g)>chemically degraded-transformer oil (480-490 ng/g) and PCBs free oil (ND-17 ng/g). Chemical degradation resulted in an order of magnitude decrease in the PCB concentrations. Specifically, higher chlorinated PCBs degraded into lower chlorinated PCBs. Also, composition of PCBs have been determined in PCB formulations from Japan (Kanechlor), Germany (Clophen), USA (Aroclor), Russia (Sovol) and Poland (Chlorofen). Major PCBs (24-PCB congeners) contributed 54-67%, 55-68%, 16-69%, 71% and 72% in Kanechlor, Clophen, Aroclor, Sovol and Chlorofen, respectively to total PCBs. The homologue pattern of Kanechlor, Aroclor and Clophen in technical fromulation was similar (e.g., Kanechlor-300 resembled to those of Clophen A-30 and Aroclor-1242). Furthermore, congener-specific distributions of major PCBs/dioxin-like PCBs and toxic equivalency quantities (TEQ) were calculated. Based on our tentative assumption calculations, cumulative production of five different technical PCB formulations, WHO-TEQ emission was estimated to be approximately 16.05 tons.     

Polychlorinated biphenyls contamination in urban soil of Shanghai: level, compositional profiles and source identification

Surface soil samples taken from 55 sampling sites at the urban areas of Shanghai were collected and analyzed for the occurrence of 144 polychlorinated biphenyls (PCBs) by GC-μECD. The results showed that totally 74 PCB congeners were identified and the mean concentration of total PCBs was 3057 ng kg⁻¹ with a range of 232 to 11325 ng kg⁻¹. Compared with the related reports, the level of PCBs contamination in this study was approximately equal to the global background value in soils, but higher than Chinese background for rural and urban soils. According to the compositional profiles of PCBs homologues, a higher proportion of low chlorinated (from tri-CBs to hexa-CBs) was observed. The results indicated that PCB15 + 13, PCB18, PCB28, PCB104 + 47 and PCB153 were the most dominant congeners among the identified PCBs. Through homologues analysis, cluster analysis and principal component analysis (PCA), it was found that PCBs were stretched from mixed local sources, and appeared to be mostly originated by Aroclor 1260- and 1254-like mixtures as well as some samples influenced by Aroclor 1232 and 1242. The correlation analysis showed the relatively good correlation among the PCB homologues and soil total organic carbon (TOC), suggesting important influence of soil TOC on PCBs contamination in soil matrix in Shanghai region. The toxic equivalency (TEQ) concentrations of these six dioxin-like PCBs detected in urban soil samples range from 2.71 to 24.9 pg kg⁻¹-PCDDeq with a mean 8.18 pg kg⁻¹-PCDDeq.     

Spatial distribution and source apportionment of PCBs in sediments around İzmit industrial complexes, Turkey

The spatial distribution, degree of pollution and major sources of PCBs were evaluated in surficial sediments within the heavily urbanized and industrialized ?zmit Bay and its main freshwater inputs. ΣPCB concentrations range from 2.90 to 85.4ngg(-1) in marine sediments and from ND to 47.7ngg(-1) in freshwater sediments. Results suggest that high concentrations of ΣPCBs were localized around a chlor-alkali plant and an industry that handles bulk liquid, dry and drummed chemicals, and petroleum products in the Bay. Using a chemical mass balance receptor model (CMB), major sources of PCBs in the region were investigated. The CMB model identified Aroclor 1254 and 1260 to be the major PCB sources in marine sediments and the less chlorinated Aroclor 1248 and 1242 as the major PCB sources in freshwater sediments. The potential sources for the PCBs were briefly discussed in terms of their use in various industrial applications.     

Congener profiles of PCB and a proposed new set of indicator congeners

In this study, a new method for calculating total PCB and toxic equivalents (TEQ) of coplanar PCB (Co-PCB) was proposed, called the 'PCB dual method'. This method analysed various kinds of technical PCB, samples contaminated by technical PCB and byproduct PCB. In the PCB dual method, a data set of 15 indicator congeners was utilized for the calculations, having IUPAC nos. #3, #8, #28, #52, #77, #101, #105, #118, #126, #138, #153, #180, #194, #206 and #209. The 15 congener set was chosen from the major congeners, determined by HRGC/HRMS analysis, in 18 technical PCB, Kanechlor, Aroclor, Clophen and Chlorofen, and 20 other samples, such as indoor air, flue gases, emission gases, municipal solid waste (MSW), ash and sealant. To obtain total PCB and TEQ of Co-PCB, the intermediate sum for the concentration of the 15 congeners was multiplied by each multiplication factor. As a result, we obtained the average factor used to calculate total PCB in technical PCB and other samples. For technical PCB, the factor was 3.01, while for indoor air samples, flue and emission gases, MSW, ash and sealants, the factors were 3.92, 4.16, 3.68, 4.52 and 4.77, respectively. Moreover, the factor used to calculate the TEQ of Co-PCB in Kanechlor and other source samples were also obtained. The factors for Kanechlor, indoor air samples and emission gases from a cement plant were in the order of 10(-5), while the factor for flue gases in a MSW incinerator was in the order of 10(-3). These data were valuable for the rough estimation of the TEQ of Co-PCB without separation from other PCB before individual measurements.     

Vertical fluxes and accumulation of PCBs in coastal sediments of the Río de la Plata estuary, Argentina

Settling particles and underlying sediments collected at 1, 2.5 and 4 km along offshore transects in the urbanized sector of the Río de la Plata were analyzed to evaluate the sources and accumulation of PCBs. Total PCB concentrations range from <0.1 to 100 ng g(-1) and include variability associated to North-South and offshore gradients reflecting the impact of coastal discharges. Highest concentrations were recorded in the industrialized Central area close to Buenos Aires (61+/-37 ng g(-1) at 1 km) relative to cleaner northern stations (3.6+/-2.2 ng g(-1)) and southward sites (37+/-2.8 ng g(-1)), affected by transport of particulate PCBs by coastal currents. Sediment traps deployed in the Central area revealed large depositional fluxes of total matter (361+/-124 gm(-2)day(-1)) and PCBs (26+/-19 microg m(-2)day(-1)) and high sedimentation rates (5.0+/-1.7 cm yr(-1)). Uniform PCB concentrations (66-89 ng g(-1)) down to 20 cm in sediment cores suggest continued PCB discharges during the last 4 years. PCB composition was dominated by hexa (43+/-6.4%), hepta (23+/-5.1%) and pentachlorobiphenyls (21+/-5.5%) with lower proportions tri-tetra (7.4+/-5.4%) and higher chlorinated congeners (5.1+/-3.3%). A consistent weathering pattern with loss of 3-5 chlorobiphenyls and enrichment in higher chlorinated PCBs corresponding to a shift from a 1:1 to a 1:3 1254:1260 Aroclor mixture, was observed offshore. A principal component analysis performed with the relative contribution of PCB congener classes confirmed the offshore weathering pattern indicating that transformer oils containing Aroclor 1254-1260 are the most probable sources. Sediment inventories, sediment trap fluxes and Fugacity II calculations indicate an accumulation approximately 500-800 kg PCB in superficial sediments of this coastal environment.     

Chlorohydrocarbons, PCB congeners, polychlorodioxins, furans and dibenzothiophenes in pine needles in the vicinity of a metal reclamation plant

Chlorohydrocarbons, PCB congeners, polychlorodioxins, furans and dibenzothiophenes in pine needles in the vicinity of a metal reclamation plant were analyzed by GC/ECD and GC/MS. Wax and the rest of the needles were analyzed separately. As a rule the concentrations of -HCH (0.5–13.6 ng/g), γ-HCH (0.4–7.3 ng/g), HCB (0.2–3.4 ng/g), PCB congeners (0.2–67 ng/g), PCDDs and PCDFs were higher in the older needles. The ratio of the concentration in the wax to the concentration in the rest of the needles was higher in the younger needles. The concentrations of PCB congeners, TeCDDs and TeCDFs were higher in the needles collected in the area nearest to the plant. The samples, obviously, contained tri- and tetrachlorodibenzothiophenes but these were not determined quantitatively due to interfering peaks in GC/MS.     

Low hepatic 7-ethoxyresorufin-O-deethylase (EROD) activity and minor alterations in retinoid and thyroid hormone levels in flounder (Platichthys flesus) exposed to the polychlorinated biphenyl (PCB) mixture, Clophen A50

The effect of the polychlorinated biphenyl (PCB) mixture Clophen A50 on hepatic cytochrome P4501A1 dependent EROD (7-ethoxyresorufin-O-deethylase) activity, plasma thyroid hormone levels and plasma, kidney and liver retinoid concentrations of the euryhaline flatfish flounder (Platichthys flesus) was determined 2 and 10 days after i.p. (intraperitoneal) injection with 20, 100 and 500 mg Clophen A50/kg body weight. No effect of Clophen A50 on total cytochrome P450 content in flounder liver was observed at both time points. A six-fold, dose-dependent, significant increase in EROD activity was found at exposure day 10 in flounder receiving 100 or 500 mg Clophen A50/kg body weight. Plasma retinol concentrations were not altered at both time points after Clophen A50 administration, whereas renal retinol levels showed a minor dose-related increase at day 2 and day 10 of exposure. Significant alterations in hepatic retinoid concentrations were observed, which were not dependent on the dose of PCB administered. In addition Clophen A50 administration did not result in a dose-related alteration of total T4 concentrations in plasma. Total T3 concentrations in plasma were only significantly increased at day 2 after exposure, whereas free T4 concentrations were increased at both time points after Clophen A50 administration. These data indicate that with regard to the parameters investigated and in contrast to other fish species studied, the flounder is not a sensitive species to PCB exposure.     

Heavy metals, PCDD/F and PCB in sewage sludge samples from two wastewater treatment facilities in Rio de Janeiro State, Brazil

Two sewage sludge samples collected from an urban as well as a rural area in Brazil and one sludge sample originating from the city of Balingen, Baden-Württemberg, South Germany, were investigated in respect to contamination with heavy metals, PCDD/F and PCB. The results were compared to PCDD/F and indicator-PCB mean values found in the region of Baden-Württemberg. The observed toxicity equivalents of PCDD/F found in the Brazilian samples, were below the upper limit specified by German legislation for final disposal or agricultural use in soils. Both the PCB and heavy metal values exceeded this limit. The PCDD/F congener/homologue profiles found in the Brazilian samples indicated that the urban sewage sludge shows a contamination where both chlorophenols and depositional sources appear to be contributing to the contamination pool. The enrichment of highly chlorinated PCDD/F groups in the sludge of semi-rural origin is probably due to transport phenomena effects. For the German sludge sample, depositional sources seem to be the main PCDD/F contamination pathway. Regarding PCB, both Brazilian samples show a homologue profile that indicates a contamination stemming from technical PCB formulations like Clophen A50 and Clophen A60 or equivalent.     

A rapid method for determination of Aroclor 1260 in cattle adipose tissue

Abstract

A simple analytical procedure for the determination of Aroclor 1260 in cattle adipose tissue is described. The polychlorinated biphenyls residues are extracted from the tissue using a soxhlet extractor and the extracts are cleaned up using a florisil SEP‐PAK cartridge. The residues are detected using a gas chromatograph equipped with an electron capture detector. The effect of extraction time of the Aroclor 1260 residues from the tissue has been investigated and a period of four hours is found to give satisfactory percent recoveries. Greater than 85 percent recoveries were obtained from adipose tissue spiked with Aroclor 1260. The method can be used to detect Aroclor 1260 residue levels as low as 0.10 parts per million.

The method was used to analyze thirty‐one cattle adipose tissue samples out of which twenty‐six samples were taken from cattle suspected of exposure to a pasture containing electrical transformers and capacitors containing Aroclor 1260. Five control samples were collected from cattle with no known exposure. All twenty‐six samples were found to contain non‐detectable Aroclor 1260 residues.     

Comparison of an enzyme-linked immunosorbent assay (ELISA) to gas chromatography (GC)--measurement of polychlorinated biphenyls (PCBs) in selected US fish extracts

The analysis of PCBs in fish tissues by immunoassay methods was evaluated using fish collected from a US monitoring program, the National Contaminant Biomonitoring Program of the US Department of Interior, Fish and Wildlife Service. Selected composite whole fish samples, which represented widely varying concentrations and sources of PCBs, were extracted and subjected to congener PCB analysis by gas chromatography (GC) and total PCB analysis using an ELISA (ePCBs) calibrated against technical Aroclor 1248. PCB congener patterns in these fishes were different from the patterns found in commercial Aroclors or their combinations as demonstrated by principal component analysis of normalized GC congener data. The sum of the PCB congeners measured by GC (total-PCBs) ranged from 37 to 4600 ng/g (wet weight). Concentrations of PCBs as determined by the ELISA method were positively correlated with total-PCBs and the ePCBs/total-PCBs ratios for individual samples ranged from 1 to 6. Ratios of ePCBs/total-PCBs for dilutions of Aroclors 1242, 1254, and 1260 and for matrix spikes range from 0.6 for 1242 to 2.5 for 1254 and 1260. These results suggest that higher chlorinated PCB congeners have higher affinity for the anti-PCB antibodies. Partial least squares with latent variable analysis of GC and ELISA data of selected Aroclors and fish samples also support the conclusion that ELISA derived PCB concentrations are dependent on the degree of chlorination.     

Levels of persistent organochlorine residues in eggs of greater flamingos from the Guadalquivir marshes (Doñana), Spain

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) residue levels were determined in 53 unhatched eggs from greater roseus flamingos (Phoenicopterus ruber). Eggs were collected in 1996 from the National Park of Do?ana (Guadalquivir marshes, Southwest Spain), immediately after one breeding colony abandoned the nesting site due to predator attacks. The main metabolite of p,p'-DDT, p,p'-DDE, was the OCP residue found at higher concentrations, with a geometric mean of 721 ng/g wet weight. Residues of other pesticides, including some hexachlorocyclohexane isomers, hexachlorobenzene, aldrin, heptachlor, and heptachlor-epoxide, were detected at much lower concentrations. The sum of PCBs was 528 ng/g, with PCB congeners #187 and #153 being the most prominent in eggs. The pattern observed in these compounds of industrial origin corresponded more to Aroclor 1260 than to any other commercial mixture. Levels of organochlorine residues indicate a medium degree of exposure, and they are not considered of any concern for the flamingo population. In particular, neither p,p'-DDE nor PCB levels were found to be correlated with the eggshell thickness.     

Organohalogenated compounds in pine needles from Beijing city, China

Pine needles collected from 22 sites of six areas in Beijing city, China, were analyzed by instrumental neutron activation analysis (INAA) combined with organic extraction for extractable organohalogens (EOX) and extractable persistent organohalogens (EPOX). The concentrations of EOX (EOX = ECl + EOBr + EOI) were in the order of EOCl > EOBr > EOI. About 1.6-34% of EOCl remained as extractable persistent organochlorine (EPOCl) after treatment with concentrated sulfuric acid, which suggested that major fractions of EOCl in pine needles were an acid-liable or acid-soluble fraction. The fact that pine needle contained higher EOCl contents in chemical industrial and traffic hub areas indicated that chemical industries and exhaust emission from vehicle were the main sources of organochlorines in the Beijing's air. The relative proportions of the known organochlorines (such as HCHs, DDTs, chlordanes, HCB and PCBs) to total EOCl and EPOCl were 0.32-0.76% and 2.5-11.4%, respectively, which implied that a major portion of the EOCl and EPOCl measured in pine needles was unknown. The organochlorinated pesticides (OCPs) and PCBs concentrations in six areas were as follows: sigma HCH (sigma HCH = alpha- + beta- + gamma- + delta-HCH), 11.7-20.8 ng/g; sigma DDT (p,p'-DDT + p,p'-DDE + p,p'-DDD), 12.5-113.3 ng/g; hexachlorobenzene (HCB), 1.1-5.3 ng/g; sigma chlordane (cis-chlordane + trans-chlordane + heptachlor), 1.7-9.5 ng/g, sigma PCB, 41.8-270.5 ng/g, on dry weight basis. The samples from chemical industrial area and residential area nearby chemical industries contained the highest concentrations of sigma DDT, HCB, sigma chlordane and sigma PCB, while the contamination levels of most OCPs and PCBs in iron-steel industrial area were the lowest. The ratios of alpha/gamma-HCH (ranged from 0.9-1.5) and p,p'-DDT/DDTs (ranged from 72.1% to 91.0%) revealed the presence of the recent use of lindane and DDTs or impure dicofol in Beijing.     

Polychlorinated biphenyls and organochlorine pesticides in EELS (Anguilla anguilla L.) from Welsh rivers

Organochlorine concentrations in the muscle tissues of eels at 41 freshwater sites across Wales were surveyed in 1993. Positive but weak relationships were detected between eel age or length and the concentration of some organochlorines. Isomers of HCH were below detection at most sites. Dieldrin was widespread at 10-100 microg kt(-1) wet weight, despite its ban in sheep dip in 1989. Total DDT residue concentrations averaged 73 microg kg(-1). Total PCB burdens expressed as Arochlor 1260, were > 50 microg kg(-1) at 76% of sites and > 100 microg kg(-1) at 46% of sites. The range of concentrations was comparable with other UK data. Rural sites had relatively low levels of PCBs, highest contamination occurring in the lower reaches of industrialised catchments. The inferences for environmental effects are discussed.     

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.

     

Source apportionment of polychlorinated biphenyls in the New York/New Jersey Harbor

The New York/New Jersey Harbor (also known as the Hudson River Estuary) is heavily contaminated with polychlorinated biphenyls (PCBs) arising in part from inputs from the Upper Hudson River, which is a Superfund site containing historical PCB contamination, and also due to inputs from the New York City metropolitan area. The Contamination Assessment and Reduction Project (CARP) measured PCBs and other contaminants in ambient water samples collected throughout the Harbor region during 1998-2001. In order to investigate the sources of PCBs to the NY/NJ Harbor, this data base of PCB concentrations was analyzed using Positive Matrix Factorization (PMF). This analysis resolved seven factors that are thought to be associated with sources such as the Upper Hudson River, storm water runoff, combined sewer overflows (CSOs), and wastewater effluents. The PMF model also produced a factor that appears to be related to sites contaminated with Aroclor 1260. To the extent that the NY/NJ Harbor is typical of urbanized estuaries throughout the United States, these results suggest that storm water runoff is probably a significant source of PCBs to surface waters in urban areas.     

Concentrations of dioxin-like PCB congeners in unweathered Aroclors by HRGC/HRMS using EPA Method 1668A

We have determined the congener compositions of nine commercial Aroclor products of polychlorinated biphenyls (PCBs) to the sub-part-per-million level using high-resolution gas chromatography combined with high-resolution mass spectrometry according to US Environmental Protection Agency (EPA) Method 1668A. These Aroclor composition data should allow improved characterization and risk assessment of PCB contamination at hazardous waste sites, particularly for dioxin-like PCB congeners. By combining the data on the concentrations of each dioxin-like congener with its World Health Organization toxicity equivalency factor, we have established dioxin toxic equivalent concentrations for each pure Aroclor product.     

Anthropogenic impacts on natural nitrogen isotope variations in Pinus sylvestris stands in an industrially polluted area

Natural variations of the nitrogen isotopes 15N/14N (delta15N values) and the N concentrations of one-year-old needles from 7-12-year-old pine trees (Pinus sylvestris L.) were determined on 27 sites in the heavily polluted Leipzig-Halle region (former GDR). At three selected sites measurements were repeated over a period of 2 years. N concentrations and delta15N values in different needle age classes were compared at the three sites. The delta15N values of the N in the humus layer and the potential plant available N in the A(h) horizon of the local soil were determined. The 15N/14N isotope ratios (delta15N values) of one-year-old pine needles in the region of Leipzig-Halle were found to vary depending on their specific location by a factor of up to one order of magnitude (-9.6 per thousand to + 0.4 per thousand ). N concentrations in one-year-old pine needles varied between 0.71 and 1.38 mmol eq N g dw(-1). Pine stands with positive or slightly negative delta15N values and high N concentrations in one-year-old needles were concentrated around the cities of Leipzig and Halle and in the industrial areas. More negative delta15N values and lower N concentrations in one-year-old pine needles were found on sites at greater distances from the industrial agglomerations, mainly in the NE forested part. Site specific differences in the delta15N values of the N in the humus layer from three selected sites were similar to those found for the needles. No site specific differences, however, were found for the delta15N values of the water soluble nitrogen fraction from the mineral soil horizons of the same sites.     

Chemical reaction of polychlorinated biphenyls on soils with poly(ethylene glycol)/KOH

Polychlorinated biphenyls (PCB's) with higher chlorination levels have been found to be highly reactive toward poly(ethylene glycol)/KOH under ambient conditions. Artificially contaminated and real world samples of PCB on soils have been reacted with PEG/KOH, affording aryl polyglycols as products. Complete reaction of Aroclor 1260 occurs in less than two weeks in open jars under ambient conditions.     

Levels of Persistent Organochlorine Residues in Eggs of Greater Flamingos from the Guadalquivir Marshes (Doñana), Spain

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) residue levels were determined in 53 unhatched eggs from greater roseus flamingos (Phoenicopterus ruber). Eggs were collected in 1996 from the National Park of Doñana (Guadalquivir marshes, Southwest Spain), immediately after one breeding colony abandoned the nesting site due to predator attacks. The main metabolite of p,p′-DDT, p,p′-DDE, was the OCP residue found at higher concentrations, with a geometric mean of 721 ng/g wet weight. Residues of other pesticides, including some hexachlorocyclohexane isomers, hexachlorobenzene, aldrin, heptachlor, and heptachlor-epoxide, were detected at much lower concentrations. The sum of PCBs was 528 ng/g, with PCB congeners #187 and #153 being the most prominent in eggs. The pattern observed in these compounds of industrial origin corresponded more to Aroclor 1260 than to any other commercial mixture. Levels of organochlorine residues indicate a medium degree of exposure, and they are not considered of any concern for the flamingo population. In particular, neither p,p′-DDE nor PCB levels were found to be correlated with the eggshell thickness.     

Regional aspects and statistical characterisation of the load with semivolatile organic compounds at remote Austrian forest sites

Spruce needles and humus layer of 25 remote forest sites spread all over Austria were investigated for their concentrations of PCDD/F, PCB, HCH, HCB, PCP, DDX and PAH. Influences of the sites' location on the detected concentrations have been identified: The north of Austria was characterised by a comparably higher overall pollutant load. In addition, altitudinal aspects were addressed. Between several compounds significant positive correlations have been identified, which were more pronounced for compounds with a stronger causal relationship. Pattern analyses allowed to identify--even for the remote sites--differences between the relative PCDD/F, HCH, DDX and PAH patterns of the sites. Partly, these different patterns were related to significantly higher or lower corresponding absolute concentrations of the sites.