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Some Polycyclic Aromatic Compounds (PACs) such as nitrated-PAHs (NPAHs), oxygenated-PAHs (OPAHs) and methyl-PAHs (MPAHs) have attracted significant concern due to derivatives have greater potential to be more toxic at low environmental concentrations compared to their PPAHs, particularly in petrochemical industrial region and its surrounding areas surface soils in China. Hence, this article provides an insight into the fate, sources, impacts, and relevance to the external environment of PAH-derivatives based on important emissions source. Moreover, prospective health risk due to their exposure has also been discussed. In this study, the concentration (10 -3  ng/g) of Ʃ18PPAHs, Ʃ11MPAHs, Ʃ12NPAHs, and Ʃ4OPAHs in the park were 9.67 ± 1.40, 3.24 ± 0.54, 0.03 ± 0.02 and 0.19 ± 0.65, respectively, which were 4.47, 3.89, 2.04 and 1.17 times than of them surrounding the region. A decreasing trend of the low molecular weight (2-4Rings) contribution to the total amount of PAHs, while the fraction of high molecular weight (5-6Rings) species showed the opposite trend. According to the principal component analysis (PCA) and diagnostic ratios indicated PAHs in the soil samples have mixed sources from industrial activities, solid fuel combustion, and heavy traffic. Despite the high concentrations of MPAHs and OPAHs, the toxicity equivalency quotients (TEQs) of them were not calculated due to the lack of toxic equivalent factors (TEF), thus current studies on PAH and derivatives could have underestimated their exposure risks. The quality and sustainable management of soils are crucial for human health and sustainable development, while there is lack of public awareness of the severe issue of soil pollution. It is recommended to conduct more intensive monitoring and regional assessments in the future., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Polycyclic aromatic compounds (PACs) are organic compounds commonly found in contaminated soil. Previous studies have shown the removal of polycyclic aromatic hydrocarbons (PAHs) in creosote-contaminated soils during steam enhanced extraction (SEE). However, less is known about the removal of alkyl-PAHs and heterocyclic compounds, such as azaarenes, and oxygen- and sulfur-heterocyclic PACs (OPACs and PASHs, respectively). Further, the impact of SEE on the freely dissolved concentration of PACs in soil as well as the soil bioactivity pre- and post-SEE have yet to be addressed. To fulfil these research gaps, chemical and bioanalytical analysis of a creosote-contaminated soil, collected from a U.S. Superfund site, pre- and post-SEE were performed. The decrease of 64 PACs (5-100%) and increase in the concentrations of nine oxygenated-PAHs (OPAHs) (150%) during SEE, some of which are known to be toxic and can potentially contaminate ground water, were observed. The freely dissolved concentrations of PACs in soil were assessed using polyoxymethylene (POM) strips and the concentrations of 66 PACs decreased post-SEE (1-100%). Three in vitro reporter gene bioassays (DR-CALUX®, ERα-CALUX® and anti-AR CALUX®) were used to measure soil bioactivities pre- and post-SEE and all reporter gene bioassays measured soil bioactivity decreases post-SEE. Mass defect suspect screening tentatively identified 27 unique isomers of azaarenes and OPAC in the soil. As a remediation technique, SEE was found to remove alkyl-PAHs and heterocyclic PACs, reduce the concentrations of freely dissolved PACs, and decrease soil bioactivities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Polycyclic aromatic compound (PAC) contamination in soil as a result of oil spills is a serious issue because of the huge global demand for fossil energy. This study assessed the vertical variation in polycyclic aromatic hydrocarbons (PAHs), derivatives of PAHs (dPAHs) and bacterial community structure in deep soil with long-term contamination by oil spillage. Our results suggest that the content of total PACs ranged from 1196.6 μg/kg to 14980.9 μg/kg and decreased with depth at all sites. PAHs were the most abundant PACs, with a mean concentration of 6640.7 μg/kg, followed by oxygenated PAHs (mean 156.3 μg/kg) and nitrated PAHs (mean 33.4 μg/kg). PAHs are mainly low molecular weight PACs such as naphthalene, fluorene and phenanthrene, while derivatives of PAHs are all low molecular weight PACs and mainly oxygenated PAHs. Low molecular weight PAHs were an important source of dPAHs under specific conditions. The bacterial community structure showed higher bacterial diversity and lower bacterial richness in shallow soil (2-6 m in depth) than in deep soil (8-10 m in depth). Spearman's analysis confirmed that dramatic bacterial community shifts are a response to contamination. At the genus level, the presence of PACs highly selected for Pseudomonas, belonging to Proteobacteria. Moreover, functional predictions based on Tax4Fun revealed that soil with long-term contamination had a strong potential for PAC degradation. In addition, statistical analysis showed that oxidation-reduction potential (Eh) was closely related to variations of bacterial community composition and function. Finally, Ramlibacter, Pseudomonas, Pseudonocardia, c_MB-A2-108, f_Amb-16S-1323, and Qipengyuania were identified by cooccurrence network analysis as keystone taxa contributing to the maintenance of bacterial ecological function. Together, our results provide evidence of tight bacterial effects of PAHs and dPAHs and a more complete understanding of the fate of PACs in deep contaminated soils., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In situ chemical oxidations are known to remediate PAH contaminations in groundwater and soils. In this study, batch-scale oxidations aim to compare the PAC (polycyclic aromatic compound) degradation of three oxidation processes traditionally applied for soil treatment: permanganate, heat-activated persulfate (60 °C) and Fenton-like activated by magnetite, to results obtained with ferrates (Fe VI ). Widely studied for water treatments, ferrates are efficient on a wide range of pollutants with the advantage of producing nontoxic ferric sludge after reaction. However, fewer works focus on their action on soil, especially on semi-industrial grade ferrates (compatible with field application). Oxidations were carried out on sand spiked with dense non-aqueous phase liquid (DNAPL) sampled in the groundwater of a former coking plant. Conventional 16 US-EPA PAHs and polar PACs were monitored, especially potential oxygenated by-products that can be more harmful than parent-PAHs. After seven reaction days, only the Fenton-like showed limited degradation. Highest efficiencies were obtained for heat-activated persulfate with no O-PAC ketones formed. Permanganate gave important degradation, but ketones were generated in large amount. The tested ferrates not only gave slightly lower yields due to their auto-decomposition but also induced O-PAC ketone production, suggesting a reactional pathway dominated by oxidoreductive electron transfer, rather than a radical one.

In an attempt to evaluate the behavior of Dechlorane plus (DP) in soil-vegetable systems, this work investigated the uptake and translocation of DP by vegetables and the dissipation of DP in soil under greenhouse and conventional conditions. To address human dietary exposure to DP, estimated dietary intake via vegetable consumption was calculated. The uptake potential indexes of DP from soil into root for tomato and cucumber cultivated under different conditions ranged from 0.089 to 0.71. The ranges of uptake potential indexes of DP from resuspended soil particles into stem, leaf and fruit were 0.68-0.78, 0.27-0.42 and 0.39-0.75, respectively. The uptake potential indexes in greenhouse vegetables were generally higher than those in conventional vegetables when the vegetables had been planted in contaminated soil, indicating that greenhouse enhanced the uptake of DP with a high soil concentration by vegetables. The translocation factor (TF) values of DP in vegetables were in the range of 0.022-0.17, indicating that DP can be transported from root to fruit even though it has a high octanol water partition coefficient (K OW ). The half-lives of DP dissipation in soil ranged from 70 to 102 days. The dissipation of DP in greenhouse soil was slightly slower than that in conventional soil. Higher estimated dietary intake (EDI) values of DP via greenhouse vegetables were observed due to the higher concentration of DP in greenhouse vegetables than conventional vegetables. These results suggested that greenhouses should not be adopted for vegetable production in contaminated regions., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

While various investigations have been driven on polybrominated diphenyl ethers (PBDEs) and other flame retardants (FRs) in different framework around the world, information about contamination and fate of PBDEs and other FRs in developing countries especially in the Indian subcontinent is uncommon. Nepal being located in the Indian subcontinent, very little is known about contamination level of semi-volatile organic pollutants discharged into the environment. This motivated us to investigate the environmental fate of halogenated flame retardant (HFRs) in Nepalese condition. In this study, we investigated the concentration, fate, and sources of 9 PBDEs, 2 dechlorane plus isomers (DPs), and 6 novel brominated flame retardants (NBFRs). Moreover, air-soil exchange and soil-air partitioning were also evaluated to characterize the pattern of air-soil exchange and environmental fate. In general, the concentrations of NBFRs in soil were more prevalent than PBDEs and DPs, and accounted 95% of ∑HFRs. By and large, the concentrations of NBFRs and DPs were measured high in Kathmandu, while PBDEs level exceeded in Pokhara. Principal component analysis (PCA) study suggested contributions from commercial penta-, octa-, and deca-BDEs products and de-bromination of highly brominated PBDEs as the significant source of PBDEs. Likewise, low f anti ratio suggested DPs in soil might have originated from long-range atmospheric transport from remote areas, while high levels of decabromodiphenyl ethane (DBDPE) in soil were linked with the use of wide varieties of consumer products. The estimated fugacity fraction (ff) for individual HFR was quite lower (<0.05) than equilibrium value, suggesting that deposition and net transport from air to the soil is overwhelming. Soil-air partitioning study revealed neither octanol-air partition coefficient (K OA ) nor black carbon partition coefficient (K BC-A ) is an appropriate surrogate for soil organic matter (SOM), subsequently, absorption by SOM has no or little role in the partitioning of HFRs., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Guiyu, China, is well-known for the crude disposal of electronic waste (EW) and severe persistent organic pollutants (POPs). Therefore, in this study, the occurrence, composition, and source of polybrominated diphenyl ethers (PBDEs), 2,2',4,4',5,5'-hexabromobiphenyl (BB153), some novel brominated flame retardants (NBFRs), Dechlorane Plus (DP) and polybrominated dibenzo-p-dioxins/dibenzofurans (PBDD/Fs) in farmland soils covering Guiyu were studied. In EW disposal area soils, PBDEs were the most abundant FRs, with concentrations of 13-1014 ng g -1 . The primary PBDE sources were technical Penta- and Deca-BDE mixtures in northern and southern Guiyu, respectively. The levels of BB153 were relatively low, possibly because it has been banned in the 1970s. The concentrations of hexabromobenzene (HBB) were 0.048-3.3 ng g -1 , while pentabromoethylbenzene (PBEB) was almost not detected in the soils. Two alternatives to commercial PBDEs, decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), were the primary NBFRs, with concentrations of 1.8-153 ng g -1 and 0.43-15 ng g -1 , respectively. DP was another primary FR, with concentrations of 0.57-146 ng g -1 . Moreover, syn-DP and anti-DP isomers were not stereoselectively decomposed during the EW disposal process and were therefore present in their original fractions in the soils. The levels of PBDD/Fs in EW disposal area soils were 2.5-17 pg TEQ g -1 . 1,2,3,4,6,7,8-HpBDF and OBDF were the dominant congeners, mainly derived from processing, pyrolysis and combustion of BFRs. The regional distribution of pollutants was shown to be related to the disposal manner of EW, with their open thermal disposal tending to release more highly brominated compounds such as BDE209, DBDPE, and 1,2,3,4,6,7,8-HpBDF. Additionally, some riverbank sites were heavily polluted because of nearby point sources, downwind Simapu (SMP) town without EW disposal activity was also contaminated by these pollutants., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

We investigated the concentrations of polybrominated diphenyl ethers (PBDEs) and alternative flame retardants (FRs) in environmental samples collected in January 2012, 2013, and 2014 from an electronic waste-processing area in northern Vietnam. During the study period, PBDE and alternative FR concentrations in soils around the electronic waste-processing workshops ranged from 37 to 9200 ng g -1 dry weight (dw) and from 35 to 24,000 ng g -1 dw; the concentrations in soils around the open-burning sites ranged from 1.6 to 62 ng g -1 dw and from <4 to 1900 ng g -1 dw; and the concentrations in river sediments around the workshops ranged from 100 to 3800 ng g -1 dw and from 23 to 6800 ng g -1 dw, respectively. Over the course of study period, we observed significant decreases in concentrations of PBDEs and significant increases in concentrations of alternative FRs, particularly Dechlorane Plus isomers and oligomeric organophosphorus FRs (o-PFRs) in both soils and sediments around the workshops. We also report information on concentrations and environmental emissions of o-PFRs and their low-molecular-weight impurities in the same soils and sediments. The detection of o-PFR impurities around the workshops and the open-burning sites highlights an enhanced breakdown of o-PFRs probably due to weathering during open storage and high temperature attained during the burning of electronic wastes., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Dechlorane 602 (Dec 602), Dechlorane 603 (Dec 603), Dechlorane 604 (Dec 604), Dechlorane 604 component B (Dec 604 CB) and Dechlorane Plus (DP) were analyzed in soil and fish collected across e-waste recycling sites in Guiyu. The results indicate that soil and fish are contaminated with dechlorane compounds especially Dec 602 and DP which show high concentrations in the samples near recycling sites. Dec 604 and Dec 604 CB are not detected. The photo-degradation experiment indicates that Dec 604 and Dec 604 CB have much faster degradation rates compared to other dechloranes, suggesting they might be more vulnerable to degradation during recycling processes and further studies are needed for assessing the environmental fate and persistence of their degradation products. Dec 602 has not been manufactured in China, the detection of Dec 602 in soil and fish implies that it might be from imports of recyclable materials from developed countries., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Dechlorane Plus (DP) isomers, along with two dechlorinated metabolites were measured in environmental matrices, chyme and digestive tract contents and tissues of chicken from an e-waste recycling site located in South China. Soil is proved to be the main source of DP in chicken rather than food because soil contributes more than 94% of total DP in chyme. In the gastrointestinal tract absorption processes, no selective absorption was observed for DP isomers during the ingestion processes. The tissue distribution of DP isomers in chicken exhibits complicated characteristics. The lipid contents in tissues are the main factors in the tissue distribution of DP, while the different blood perfusion state and the different tissue functions also seem to influence the tissue distribution of DP. The fat, brain, and liver exhibit higher fanti values (0.65, 0.64, and 0.64) than the other tissues (0.54-0.59). The elevated fanti values of DP from the contamination source (0.52 in soil) to chicken suggest stereoselective bioaccumulation of anti-DP in chicken. The similar ratios of anti-Cl11-DP to anti-DP between soil and chicken imply that anti-Cl11-DP mainly derives from the uptake from environment rather than in vivo dechlorination., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Hydrophobic organic contaminants in soils may pose toxicity or transfer to food chains after their uptake to soil biota. However, uptake data for earthworms are usually limited, as: (a) only fixed exposure times are studied instead of whole uptake kinetics and (b) studies including compounds with different environmental properties and more than two soils of different properties are quite rare. In our study, five persistent organic pollutants (phenanthrene, pyrene, lindane, p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), and polychlorinated biphenyl congener No. 153 (PCB 153)) were added to six soils of a wide range of soil properties. Detailed kinetics of uptake to earthworms Eisenia fetida were measured. Results indicated that an equilibrium of concentrations for p,p'-DDT and PCB 153 was reached after 11 days of exposure in all soils. Uptake of phenanthrene, pyrene, and lindane was strongly influenced by the decrease in concentrations in the soils, resulting in peak-shaped accumulation curves. Only in soils with the highest total organic carbon content (7.9 and 20.2%), the equilibrium of lindane concentrations was achieved (after 17 and 5 days of exposure, respectively). We recommend calculating bioaccumulation factors as a ratio of the uptake and elimination rate constants to precise the risk assessment., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Eighty-seven soil samples collected from North China were analyzed for Dechlorane Plus (DP). The concentrations of DP ranged from not detectable (ND) to 12.21 ng/g with a mean of 0.55 ng/g. The mean concentrations of total DP and syn-DP in four regions of North China were in the following order: Jingjin (Beijing and Tianjin) > Shandong > Shanxi > Hebei, while the mean concentrations of anti-DP in the four regions were in a different order: Shandong > Jingjin > Shanxi > Hebei. The mean f syn values for Jingjin (0.27), Hebei (0.24), and Shanxi (0.24) were close to 0.25, while the mean f syn value for Shandong (0.31) was closer to 0.35. In addition, the f syn value for Shandong was significantly higher (P < 0.01) than those of the other regions (Jingjin, Heibei, and Shanxi), indicating specific sources of DP. Syn-DP displayed a strong linear relationship with anti-DP (R(2) = 0.74), indicating that no obvious stereoselective process occurred in the soil of North China. Ordinary kriging was undertaken to map the spatial patterns of DP. High concentrations of DP in soils were present in south of Shanxi, central Hebei, south of Tianjin, and the south and northeast of Shandong, which were suggested to be connected with human activities such as e-waste dismantling.

Dechlorane Plus (DP) is a high-production volume, chlorinated flame retardant comprising two major isomers, syn- and anti-DP. In this study, levels of DP were measured in soil and earthworm samples in farmland from a typical E-waste dismantling area in China. The concentrations of total DP ranged from 0.17 to 1,990 ng g(-1) dw in soil samples and 3.43 to 89.2 ng g(-1) lw in earthworm samples. Higher DP levels were found in some main E-waste dismantling sites than those in other sites. The ratios of anti-DP to total DP (f anti) ranged from 0.57 to 0.80 in soil samples and 0.47 to 0.81 in earthworm samples, respectively. The f anti in most samples in this study was in the range of the reported technical DP values. These results showed that improper E-waste dismantling activities could result in the emission of DP. Most earthworm samples showed very low BSAFs (biota-to-soil accumulation factors) for total DP. The values of BSAF were in the range of 0.0007-1.85, with an average value of 0.23. This study presents the first report of the DP in earthworms, which would be useful for ecological risk assessment of DP in terrestrial ecosystem.

Receptor models are useful tools to identify sources of a specific pollutant and to estimate the quantitative contributions of each source based on environmental data. This paper reports on similarities and differences in results achieved when testing three receptor models for estimating the sources of polycyclic aromatic hydrocarbons (PAHs) in soils from Huanghuai Plain, China. The three tested models are Principal Component Analysis with Multiple Linear Regression (PCA-MLR), Positive Matrix Factorization (PMF) and Unmix. Overall source contributions as well as modeled ∑PAHs concentrations compared well among models. All three models apportioned three common PAH sources: wood/biomass burning, fossil fuel combustion and traffic emission, which contributed on average 27.7%, 53.0% and 19.3% by PCA-MLR, 36.9%, 27.2% and 16.3% by PMF, and 47.8%, 21.1% and 18.3% by Unmix to the total sum of PAHs (∑PAHs), respectively. Moreover, the spatial evolution of the common sources were well correlated among models (r=0.83-0.99, p<0.001). In addition, the PMF and Unmix models allowed segregating an additional source from the fossil fuel combustion source, with 19.6% and 11.8% contributions to ∑PAHs, respectively. The current findings further validate that different receptor models provide divergent source profiles, which are mainly attributed to both the model itself and/or the underlying dataset. It is therefore generally recommended to apply multiple techniques to determine the source apportionment in order to minimize individual-method weaknesses and thereby to strengthen the conclusion., (Copyright © 2012 Elsevier B.V. All rights reserved.)

In this study, flotation-assisted homogeneous liquid-liquid microextraction (FA-HLLME) was developed as a fast, simple, and efficient method for extraction of four polycyclic aromatic hydrocarbons (PAHs) in soil samples followed by gas chromatography-flame ionization detector (GC-FID) analysis. A special home-made extraction cell was designed to facilitate collection of the low-density extraction solvent without a need for centrifugation. In this method, PAHs were extracted from soil samples into methanol and water (1:1, v/v) using ultrasound in two steps followed by filtration as a clean-up step. The filtrate was added into the home-made extraction cell contained mixture of 1.0 mL methanol (homogenous solvent) and 150.0 μL toluene (extraction solvent). Using N(2) flotation, the dispersed extraction solvent was transferred to the surface of the mixture and was collected by means of a micro-syringe. Then, 2 μL of the collected organic solvent was injected into the GC-FID for subsequent analysis. Under optimal conditions, linearity of the method was in the range of 40-1000 μg kg(-1) soil (dry weight). The relative standard deviations in real samples varied from 5.9 to 15.2% (n=4). The proposed method was successfully applied to analyze the target PAHs in soil samples, and satisfactory results were obtained., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A screening method for the soil analysis of 15 Environmental Protection Agency-polycyclic aromatic hydrocarbons (EPA-PAHs) is reported. The new method is based on the collection of 4.2 K fluorescence time-resolved excitation-emission cubes (TREECs) via laser-excited time-resolved Shpol'skii spectroscopy. 4.2 K fluorescence TREECs result from the superposition of fluorescence time-resolved excitation emission matrices recorded at different time windows from the laser excitation pulse. Potential interference from unknown sample concomitants is handled by processing the four-way 4.2 K fluorescence TREEC data arrays with either parallel factor analysis (PARAFAC) or unfolded partial least-squares/residual-trilinearization(U-PLS/RTL). The sensitivity of the two approaches makes possible to determine PAHs at the ng g(-1) to pg g(-1) concentration level with no need for sample pre-concentration. Its selectivity eliminates sample clean-up steps and chromatographic separation. These features reduce PAH loss, analysis time and cost. The method is environmentally friendly as the complete screening of the 15 EPA-PAHs takes only 250 μL of organic solvent per sample., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The occurrence and the distribution of 16 USEPA priority pollutants polycyclic aromatic hydrocarbons (PAHs) were investigated in two alluvial sandy soil profiles and in their four sizes of organo-mineral particles (<2 μm clay, 2-20 μm silt, 20-200 μm fine sand, and >200 μm coarse sand) beside a typical oil sludge storage site in eastern China. PAHs were mainly enriched in the surface soil (0-20 cm) and the concentrations declined in deeper soils, from 3.68 to 0.128 μg/g in profile 1 and 10.8 to 0.143 μg/g in profile 2 (dry wt.). The PAHs in the upper soil layers of this study site mainly came from combustion pollution, whereas in the lower soil layers petroleum contamination became the major source of PAHs. The content of different sized organo-mineral particles of this alluvial sandy soil decreased in the following order: fine sand>coarse sand>silt>clay. X-ray diffraction (XRD) results showed that all the different sized soil fractions of this study site were dominated by quartz, calcite and feldspar. The particle surface became smoother with size increasing as shown by scanning electron microscope (SEM) images. PAH concentrations varied largely in different sized soil fractions. The highest PAH concentration was associated with clay and decreased in the order: clay>silt>coarse sand>fine sand. Soil organic matter (SOM) content, mineral composition and particle surface characteristics were suggested as three main factors affecting the distribution of PAHs in different sized organo-mineral particles. This study will help to understand the distribution and transport characteristics of PAHs in soil profiles at petroleum-contaminated sites., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Dechlorane Plus (DP) is a highly chlorinated flame retardant. Levels of DP were measured in surface soils from e-waste recycling areas and industrial areas in South China. Higher DP levels were found in e-waste recycling areas (undetectable-47.4 ng/g) than those in industrial areas (0.0336-4.65 ng/g) in South China. The highest DP concentration (3327 ng/g) was found at the e-waste recycling site in Qingyuan, while DP levels fell dramatically with increasing distance away from the recycling site, suggesting that the e-waste recycling activities are an important source of DP emissions. The mean ratios of anti-DP to total DP (fanti) for different sampling areas ranged from 0.58 to 0.76 and showed no significant difference from the ratio for the technical DP products (t-test, p>0.05). Further intensive studies are needed to investigate the process of DP degradation and its degradation products., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

Dechlorane Plus (DP) has been used as a highly chlorinated flame retardant substituting those that are now internationally regulated under the Stockholm Convention. Nevertheless DP's environmental behavior has seldom been studied in China. There is only one DP manufacturer producing DP since 2005, which is located in Huai'an, Jiangsu Province. The DP levels in 21 soil samples that were taken from Huai'an in October 2009 and determined by gas chromatography/electron-capture negative ion-mass spectrometry (GC/ECNI-MS) method ranged from 0.83 to 1.2 x 10(3) ng g(-1), following a lognormal distribution. The geometric mean was 5.1 ng g(-1) dry weight (dw) and the geometric standard deviation was 4.6. Sampled soils had f(anti)[C(anti)(-DP)/(C(syn)(-DP)+C(anti)(-DP))] values of 0.67-0.85, with the average value of 0.79, which are close to the values in DP commercial products. This suggests that the main DP pollution source is the commercial DP product. The contour map of DP levels in soil indicated that the factory was the point pollution source with the highest DP level in its surrounding area, especially the southern area. A Monte Carlo based inventory estimation was conducted. The DP inventory in Huai'an is estimated to be 4-31 tons. To our knowledge, this study is the first that reports soil pollution by DP., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

The Botanical Garden lies within the city of Palermo, a few meters away from one of the largest unused Manufacturing Gas Plant in Sicily. The total concentrations of PAHs (23 compounds) in the soil of Botanical Garden ranged from 947 to 18,072 microg/kg. The wide range of PAH concentrations (RSD=84%) found in the soil samples indicates heterogeneous levels of contamination in the area and this can be explained by considering the different tree distributions which prevents the homogeneous deposition of pollutants on the soil. Soils collected in the Botanical Garden generally showed the highest PAH concentrations, being almost 2-3 times higher than the concentration samples obtained in the urban reference sites and about 20 times higher than those in the rural stations. The total PAH concentrations, in the Botanical Garden soil, resulted higher than the maximum concentrations allowed by the Italian legislation for the green areas. Perylene, was found in all the stations. From a careful study of the isomeric ratios, we can hypothesize that the soils of the Botanical Garden are mainly affected by localized MGP particulate deposition, suggesting that the partitioning between organic matter and PAHs is not the dominant process in the soils with higher organic matter content., (Copyright 2010 Elsevier B.V. All rights reserved.)

The distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments from rivers and canals adjoining some oil exploration sites in the Niger Delta and surface soils from host communities were examined. The concentrations of 28 target PAHs ranged from 65 to 331 ng/g (average: 168 ng/g) and from 24 to 120 ng/g (average: 80 ng/g) in the sediment and soil samples, respectively. Two-ring PAHs were the dominant components accounting for approximately 45% of the total PAHs detected. Assessment of the PAH compound ratios, phenanthrene/athracene (Phe/Ant) and fluoranthene/pyrene (Flu/Pyr), suggested that the PAHs in most sediment samples were predominantly of petrogenic origin which may have resulted from incessant oil pipeline leakages in the area. On the other hand, PAHs of pyrogenic sources were present predominantly in surface soils, an indication that gas flaring associated with oil exploration work in the Delta mostly affects the surface soils. An assessment using a set of widely cited sediment quality guidelines indicated that the majority of the sediment samples collected from the rivers of the delta does not pose a serious threat to the ecosystem except for two locations, Imo river and Oginni canal where PAH-contaminated sediments were likely to be acutely toxic to certain sediment dwellers.

A method for the determination of polycyclic aromatic hydrocarbons (PAHs) in soil samples using ultrasonic-assisted extraction with internal surrogates combined with solid-phase microextraction and GC-MS has been developed. Five kinds of commercial solid-phase microextraction fibers, 100 microm PDMS, 30 microm PDMS, 65 microm PDMS/DVB, 50 microm DVB/CAR/PDMS and 85 microm PA, were compared to choose the optimal SPME fiber for extraction of PAHs. One hundred micrometers of PDMS fiber was found to be more suitable for the determination of PAHs due to its wider linear range, better repeatability, lower detection and more satisfactory efficacy than the other fibers. Under the recommended conditions, 100 microm PDMS fiber could provide low nanogram level detection limits with correlation coefficient greater than 0.98. The method was also applied to determine PAHs in a spiked soil sample, obtaining recoveries higher than 79.3%. A field study with naturally contaminated samples from local contaminated sites was carried out. The proposed method was found to be a reliable, inexpensive and simple preparation method for quantitative determination of 16 PAHs in soil samples.

Polycyclic aromatic hydrocarbons (PAHs) were investigated in the surface soils from Dashiwei and Datuo Karst tiankengs, Guangxi Province, South China. Concentrations of total PAHs ranged from 16.93 ng g(-1) to 190 ng g(-1) with a mean of 58.29 ng g(-1). In Dashiwei more PAHs were concentrated than in Datuo (mean 74.42 ng g(-1) > 42.15 ng g(-1)). Dashiwei and Datuo accounted for the majority of all PAHs concentrated in the lower location through increased rates (58% and 37%) from the upper to lower geographical levels, respectively. Dashiwei presented the stronger trapping ability for heavier molecular weights on the tiankeng floor with a concentration increase rate of 167% when compared to that of the lighter molecular weights (which had a concentration increase of rate 6%), which was in contrast to the Datuo with a concentration increase rate of 37% for lighter molecular weights and 31% for heavier molecular weights. In Dashiwei, it was found that the ratio of heavier PAH compound molecular weight resulted in its higher precipitation recording on the tiankeng floor. The differentia between two tiankengs, therefore, are related to their environmental characteristics and the PAHs physiochemical properties. The analytical result from the PAHs indicators suggest that a petrogenic source was dominant in the area studied. Therefore, the karst tiankeng has the potential to act as a geophysical well for PAHs deposition, especially for the heavier molecular weighted PAH.

Polycyclic Aromatic Hydrocarbons (PAHs) are a major group of pollutants whose occurrence in the environment is mainly of anthropogenic origin. In this paper, we examine the effect of topographical slope exposure on PAH contamination and seasonal change in PAH concentrations in soils. We collected soil samples on three dates in 2007 (early May, end of July and beginning of November) from south- and north-facing aspects at 1900 m a.s.l. in the central Italian Alps. We found greater PAH contamination in soils from a north-facing slope than in those from a south-facing slope at all seasons. We calculated North-South Enrichment Factors as the ratio between the concentrations measured in soils from northern and southern aspects. These ratios ranged from 1.4 to 1.9 for lighter PAHs (from 2 to 4 rings). These values are consistent with theoretical calculations based on temperature-specific octanol-air partition coefficients (predicted North-South Enrichment Factors range from 1.6 to 2.0). For heavier PAHs (from 5 to 6 rings), smaller differences were observed between soils from northern and southern aspects, due to the gas/particle distribution of these compounds. We also found consistent differences in normalised PAH concentrations across the three sampling periods. The majority of compounds showed a significant decreasing trend from the beginning of May to the end of July, due to the annual cycles of physical processes (deposition vs. volatilisation) and biological processes (uptake and/or biotransformation). Only a few compounds showed different trends, presumably due to season-specific local emission sources.

A total of 10 surface soil samples representing the entire area of Linfen City were collected and analyzed for the presence of 16 polycyclic aromatic hydrocarbons. The total polycyclic aromatic hydrocarbon concentration ranged from 1.1 to 63.7 microg g(-1). Analysis of the sources of contamination revealed that polycyclic aromatic hydrocarbons in the soil were derived from combustion sources. Specifically, the primary source of polycyclic aromatic hydrocarbons was coal combustion, but the samples were also effected to varying degrees by traffic emissions. Furthermore, increased levels of contamination were observed in northeast Linfen due to the distribution of industrial plants.

The contents and distribution of 20 polycyclic aromatic hydrocarbons (PAHs) and heterocyclic aromatic hydrocarbons (HAHs) were investigated in 16 soil profiles of Beijing and Tianjin region. Transport of high molecular weight PAHs (HMWPAHs) and the correlation between total organic carbon (TOC) and their concentrations were also discussed. The results indicated that highly contaminated sites were located at urban or wastewater irrigation areas and pollutants mainly accumulated in topsoil (< 40 cm), with a sharp content decrease at the vertical boundary of 30-40 cm. Total PAHs/HAHs concentrations in soils from Tianjin were markedly greater than those from Beijing. Even the contents at bottoms of soil profiles in Tianjin were higher than those in topsoils of Beijing soil profile. HMWPAHs dominated the PAH profiles, exhibiting a uniform distribution of pyrogenic origin between topsoils and deep layers. Furthermore, the percentages of HMWPAHs remained relative constant with the depth of soil profiles, which were consistent with the distribution of particulate matter-associated PAHs in the local atmospheric environments. Therefore, HMWPAHs transport with particulates might be the predominant source found in soil profiles.

The surface soil concentrations (0-20 cm) of the Swiss soil monitoring network (NABO) with 105 observation sites representing all major land use types ranged for the sum of 16 EPA PAH (PAH(16)) from 32 to 8465 microg kg(-1) (median 163 microg kg(-1)), for benzo[a]pyrene (BaP) from 0.5 to 1129 microg kg(-1) (median 13 microg kg(-1)) and for the sum of seven IRMM PCB (PCB(7)) from 0.5 to 12 microg kg(-1) (median 1.6 microg kg(-1)). The legal guide values of Switzerland were exceeded for PAH(16) at only three and for BaP at two sites. The PCB(7) concentrations were clearly below any assessment value. The concentration ranges were overlapping between all land use types. Tendencies for higher concentrations were observed at urban and viticulture sites. The overall measurement precision at repeatability conditions ranged from 1 to 37% RSD for PAH(16), BaP and PCB(7). The median bias for the chemical analysis was around zero for PAH(16), +5% for BaP and -5% for PCB(7) with spreads ranging from less than -20% up to more than +30%. The PAH profiles were clearly dominated by phenanthrene. Stratification by land use revealed a prevalence of benzo[a]pyrene at urban and naphthalene at conservation sites. For PCB, the general congener rank order was PCB no. 153 > 138 > 101 > 180. From a broad correlation screening only PAH(16)/BaP (r = 0.88**) were relevant for practical soil protection. The extensive comparison with other studies was severely biased by the lack of harmonisation, especially concerning sampling depth, sampling support, analytical method and the sum calculation procedure.

In this study a large dataset on the polycyclic aromatic hydrocarbon (PAH) content of Swiss soils was analysed to evaluate two source apportionment tools, i.e., characteristic PAH ratios/molecular markers and a linear mixing model. Population density and total organic carbon (TOC) content were identified by a multiple regression model as independently and positively influencing the PAH concentrations in Swiss background soil. Specifically, TOC was more strongly positively correlated with the sum of light PAH (naphthalene to phenanthrene) than with the sum of heavy PAH (anthracene to benzo[ghj]perylene), whereas population density was more strongly positively correlated with the sum of heavy PAH than with light PAH. In addition, the sum of the heavy PAH as well as the total sum correlated negatively with sample site altitude. It is therefore hypothesised that heavy PAH are less mobile, whereas light PAH were closer to equilibrium with TOC in the soil. Similar results were found for polychlorinated biphenyls (PCB). The characteristic ratios and molecular markers pointed to pyrogenic origin of PAH in Swiss background soil but did not allow for further differentiation of individual fuel contributions, even though attempts to take environmental fractionation processes into account were made. The comparison of three soil profiles identified with a linear mixing model from the pattern of 16 PAH with >300 PAH emission profiles from the literature suggested urban dust, wood combustion and binders from asphalt as PAH sources. However, also here, environmental fractionation processes probably obscured source characteristic PAH ratios and fingerprints, which thus need to be interpreted with caution.

The concentration levels, source, and inventories of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in 55 surface vegetable soils in the watershed of the Pearl River Delta (PRD) were analyzed and compared with those of the surface sediments in the Pearl River Estuary (PRE) and northern South China Sea (SCS). The 16 priority PAHs on US EPA list range from 58 to 3,077 microg/kg (average: 315 microg/kg). The concentrations of DDTs and HCHs range from 3.58 to 831 microg/kg (average: 82.1 microg/kg) and from 0.19 to 42.3 microg/kg (average: 4.42 microg/kg). The ratios of DDT/ (DDD+DDE) are higher than 2 in majority of the soil samples, suggesting that DDT contamination still exists. The PAH ratios suggest that the source of PAHs is petroleum, and combustion of fossil fuel, biomass, and coal. The average concentrations of PAHs and the linear regression slope between PAHs and TOC for the soils and the sediments are quite similar. It was estimated that the soil mass inventories at 0-20 cm depth are 1,292 metric tons for PAHs and 356 metric tons for OCPs in the studied region. The average PAHs inventory per unit area for the soil samples investigated in PRD is about 0.86 time that of surface sediments in the Pearl River Estuary, and about 2.43 times that of surface sediments in the northern South China Sea. PAHs in the soils in PRD have similar source to those of the surface sediments in PRE. All of those may suggest that PAHs in PRE and SCS are probably mainly inputted from the soils in PRD via soil erosion and river transport.

The occurrence and distribution of polycyclic aromatic hydrocarbons (PAHs) in vegetable soils from five vegetable fields (including: Liuhe, Xixia, Pukou, Jianye and Yuhua districts) in Nanjing outskirt were investigated with high performance liquid chromatography (HPLC) equipped with fluorescence detector. The total concentrations of 15 priority PAHs in 126 soil samples ranged from 21.91 to 533.84ng g(-1) dry weight, and the sum of seven carcinogenic PAHs concentrations varied from 1.48 to 236.19ng g(-1) dry weight. Statistical analysis of the PAHs concentrations showed that the highest PAHs concentration was observed in Liuhe, and the lowest PAHs concentrations were found in Xixia among the five districts. The ratios of fluoranthene to sum of fluoranthene and pyrene concentrations (Flt/(Flt+Pyr)) were more than 0.5 in 99% of vegetable soil samples, showing that the PAHs in soils were generally derived from straw and coal combustion sources. The results from principal component analysis (PCA) further indicated that extensive combustion activities affected the PAHs distribution in Nanjing vegetable soils.

Present study was undertaken to determine the level of PAH contamination due to jet turbine exhaust in the peripheral soil of the International Airport in Delhi, India. Densely populated residential areas surrounding the airport come directly under both the landing and take-off flight paths. Twelve priority polycyclic aromatic hydrocarbons (PAHs) were analyzed in the <2 mm surface soil fraction. Identification and quantification of PAHs was done by high performance liquid chromatography (HPLC). The sum of 12 PAHs ranged from 2.39 microg g(-1) to 7.53 microg g(-1) with a mean concentration of 4.43+/-1.45 microg g(-1). PAH levels observed in the present study were found to be higher as compared to most of the literature values. Among the three sampling sites selected around the International Airport, the site near landing point revealed maximum concentration of PAHs, while minimum concentration was observed at the site near take-off point. Predominance of pyrene was observed in the airport soil. Factor analysis and isomer pair ratios suggest pyrogenic origin of PAHs in the study area.

Phytoremediation offers an ecologically and economically attractive remediation technique for soils contaminated with polycyclic aromatic hydrocarbons (PAHs). In addition to the choice of plant species, agronomic practices may affect the efficiency of PAH phytoremediation. Inorganic nutrient amendments may stimulate plant and microbial growth, and clipping aboveground biomass might stimulate root turnover, which has been associated with increases in soil microbial populations. To assess the influence of fertilization and clipping on PAH dissipation in a nutrient-poor, aged PAH-contaminated soil, a 14-mo phytoremediation study was conducted using perennial ryegrass (Lolium perenne) as a model species. Six soil treatments were performed in replicate: unplanted; unplanted and fertilized; planted; planted and fertilized; planted and clipped; and planted, clipped, and fertilized. Plant growth, soil PAH concentrations, and the concentrations of total and PAH-degrading microorganisms were measured after 7 and 14 mo. Overall, planting (with nearly 80% reduction in total PAHs) and planting + clipping (76% reduction in total PAHs) were the most effective treatments for increased PAH dissipation after 14 mo. Fertilization greatly stimulated plant and total microbial growth, but negatively affected PAH dissipation (29% reduction in total PAHs). Furthermore, unplanted and fertilized soils revealed a similar negative impact (25% reduction) on PAH dissipation after 14 mo. Clipping did not directly affect PAH dissipation, but when combined with fertilization (61% reduction in total PAHs), appeared to mitigate the negative impact of fertilization on PAH dissipation. Therefore, fertilization and clipping may be included in phytoremediation design strategies, as their combined effect stimulates plant growth while not affecting PAH dissipation.

Little is known about the spatial connection between soil microbial community composition and polycyclic aromatic hydrocarbon (PAH) concentration. A spatially explicit survey at a creosote-contaminated site demonstrated that microbial biomass (total concentration of phospholipid fatty acids [PLFAs]) and microbial community composition (PLFA fingerprints) were spatially autocorrelated, mostly within a distance of 25 m, and covaried with PAH concentrations. The concentration of PLFAs indicative of gram-negative bacteria (16:1omega7c, 16:1omega7t, 18:1omega7, cy17:0, and cy19:0) increased in the PAH hot spots, whereas PLFAs representing fungi and gram-positive bacteria (including actinomycetes) were negatively correlated to PAH concentrations. Most PLFAs were spatially autocorrelated, with distances varying between 4 and 25 m. Those PLFAs that increased in PAH-contaminated soil had autocorrelation ranges between 4 and 16 m, whereas the fungal indicator PLFA 18:2omega6,9 had the largest autocorrelation range (25 m). Bacterial strains isolated using a spray-plate technique and with the same PLFA composition as that in contaminated soil samples were capable of degrading phenanthrene, fluoranthene, and pyrene, indicating that the main PAH degraders could be isolated.

The concentrations, distribution and sources of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in 30 agricultural soil and 16 vegetable samples collected from subtropical Shunde area, an important manufacturing center in China. The total PAHs ranged from 33.7 to 350 microg/kg in soils, and 82 to 1,258 microg/kg in vegetables. The most abundant individual PAHs are phenanthrene, fluoranthene, chrysene, pyrene and benzo(b)fluoranthene for soil samples, and anthracene, naphthalene, phenanthrene, pyrene and chrysene for vegetable samples. Average vegetable-soil ratios of total PAHs were 2.20 for leafy vegetables and 1.27 for fruity vegetables. Total PAHs in vegetable samples are not significantly correlated to those in corresponding soil samples. Principal component analyses were conducted to distinguish samples on basis of their distribution in each town, soil type and vegetable specie. Relatively abundant soil PAHs were found in town Jun'an, Beijiao, Chencun, Lecong and Ronggui, while abundant vegetable PAHs were observed in town Jun'an, Lecong, Xingtan, Daliang and Chenchun. The highest level of total PAHs were found in vegetable soil, followed by pond sediment and "stacked soil" on pond banks. The PAHs contents in leafy vegetables are higher than those in fruity vegetables. Some PAH compound ratios suggest the PAHs derived from incomplete combustion of petroleum, coal and refuse from power generation and ceramic manufacturing, and paint spraying on furniture, as well as sewage irrigation from textile industries. Soil PAHs contents have significant logarithmic correlation with total organic carbon, which demonstrates the importance of soil organic matter as sorbent to prevent losses of PAHs.

The effect of Tween 80 and selected bacteria additions on the bioremediation of PAH contaminated landfill soil (70.38mgkg(-1)) was evaluated in a slurry phase bioreactor. A phenanthrene-degrading consortium was selected by enrichment cultures and used as autochthonous inoculum. The Tween 80 addition increased the aqueous concentration of both high and low molecular weight PAHs. In the experiment with Tween 80 and inoculum addition, added microorganisms improved (>90%) the biodegradation of two- and three-ring PAHs as well as of the four-ring PAHs pyrene and fluoranthene. Biodegradation of the higher molecular weight PAHs was about 30% in experiments with Tween 80 addition, with and without inoculum addition.

Oil spills due to oil pipelines is a very frequent problem in Mexico. Petroleos Mexicanos (PEMEX), very concerned with the environmental agenda, has been developing inspection and correction plans for zones around oil pipelines pumping stations and pipeline right-of-way. These stations are located at regular intervals of kilometres along the pipelines. In this study, two sections of an oil pipeline and two pipeline pumping stations zones are characterized in terms of the presence of Total Petroleum Hydrocarbons (TPHs) and Polycyclic Aromatic Hydrocarbons (PAHs). The study comprehends sampling of the areas, delimitation of contamination in the vertical and horizontal extension, analysis of the sampled soils regarding TPHs content and, in some cases, the 16 PAHs considered as priority by USEPA, calculation of areas and volumes contaminated (according to Mexican legislation, specifically NOM-EM-138-ECOL-2002) and, finally, a proposal for the best remediation techniques suitable for the contamination levels and the localization of contaminants.

Water and soil samples from the vicinity of Agbabu bitumen field of Southwestern Nigeria, were analyzed qualitatively and quantitatively for 10 parent polycyclic aromatic hydrocarbons (PAHs) using gas chromatography coupled by flame ionization detector (GC-FID), in order to gather information on the degree of contamination by bitumen exploration and processing in this area. The total concentrations of 10 PAHs varied from 11.2 to 341.5 microg L(- 1) in water and from 101.5 to 209.7 ng g(- 1) dry weight in soils. The total PAH levels in water samples from all the sampling stations (except at station WB 11), were sufficiently high (> 10 microg/L) to cause acute toxicity to the exposed organisms. Special PAH compound ratios, such as phenanthrene/anthracene and fluoranthene/pyrene, were calculated to evaluate the relative importance of different origins. The collected data indicate pyrolytic and petrogenic sources. The anthropogenic PAHs, i.e., pyrene and benzanthracene exhibited similar distribution patterns in the studied area, implying that these compounds possess identical sources. Also, dibenzothiophene, a sulfur heterocyclic aromatic compound was determined in this study and it was not detected in all the samples analyzed.

The polycyclic aromatic hydrocarbons (PAHs) naphthalene, acenaphthylene, acenaphthene, fluorene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, ideno[1,2,3,-cd]-pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene and the polychlorinated biphenyls (PCBs) 8, 18, 28, 29, 31, 52, 77, 101, 105, 114, 118, 123, 126, 128, 138, 141, 149, 153, 156, 157, 163, 169, 170, 171, 180, 183, 187, 189, 194, 199, 201, 206, and 209 were measured in -200 rural soils across Great Britain (GB). Dominance of soil PAH profiles by heavier compounds (4-6 rings) provided initial evidence for the importance of source in governing soil PAH concentrations. No relationship was found between soil organic matter (SOM) and sum concentration of total and "heavy" PAHs, although there was a weak positive relationship with lighter compounds. A spatial statistical technique showed that highest soil PAH concentrations were usually found close to industrial/urban centers where presumably source intensity is highest. PCBs clustered into seven groups, five of which contained a single "dioxin like" PCB, one contained lighter congeners (2-4 chlorines), and one contained heavy congeners (5-10 chlorines). Linear regressions with SOM explained up to 24.3% of variation for the sum concentration of penta- to deca- congeners, but <1% for the lighter congener groups. No significant relationships were found with latitude. Spatial statistical techniques showed clusters of high soil PCB concentrations predominantly in west and south east GB, either associated with urbanized areas or on the West coast.

Freely dissolved aqueous concentrations in the soil pore water represent an important aspect of bioavailability and risk assessment of contaminated soils. In this study, a negligible depletive partitioning based sampling technique was validated and applied to measure free concentrations of polycyclic aromatic hydrocarbons (PAHs) in spiked, aged and field-contaminated soils. Detailed kinetic studies were performed to select appropriate equilibration times. Freely dissolved aqueous concentrations in the pore water were compared to total concentrations, and sorption coefficients were calculated. Results show that equilibrium partition models can predict sorption coefficients of freshly spiked and lab-aged soils rather accurately. However, freely dissolved pore water concentrations of field-contaminated soils are orders of magnitude lower than model predictions. Consequently, environmental risks can be highly overestimated with these models. The simple and sensitive partitioning-based sampling technique used in this study, could, therefore, be applicable to improve site-specific risk assessment of field-contaminated soils.

Polycyclic aromatic hydrocarbons (EPA-PAHs) in the urban surface soils from Beijing were determined using gas chromatography and mass spectrometry (GC-MS). It is significantly complementary for understanding the PAHs pollution in soil of integrated Beijing city on the basis of the information known in the outskirts. The total concentration of 16 EPA-PAH was from 0.467 to 5.470 microg/g and was described by the contour map. Compound profiles presented that the 4-, 5- and 6-ring PAHs were major compositions. The correlation analysis showed that PAHs have the similar source in the most sampling sites and BaP might be considered as the indicator of PAHs. Characteristic ratios of anthracene (An)/(An+ phenanthrene (Phe)), fluoranthene (Flu)/(Flu+ pyrene (Pyr)) and benzo [a]pyrene (BaP)/benzo [g,h,i]perylene (BghiP) indicated that the PAHs pollutants probably mainly originated from the coal combustion and it was not negligible from vehicular emission. The level of PAHs in our study area was compared with other studies.

Supercritical fluid extraction (SFE) with pure carbon dioxide was used to obtain desorption curves of PAHs from four contaminated industrial soils. Total PAH concentrations ranged from 1495 to 2439 mg/kg. The desorption curves were fitted with a simple two-site model to determine the rapidly released fraction (F) representing bioavailability of PAHs. The Fdata obtained under various SFE pressures were compared with degradation results of a composting method applied on the soils. After composting and consequent long-term maturation, the residual PAH contaminations ranged from 4 to 36% of the original values. A possible explanation of the result variations is the different bioavailability of the pollutants. The best correlations between degradation results and F fraction were obtained applying 50 degrees C and 300 bar. The F values gave very good agreement with degradation efficiencies and the total regression coefficients (r) ranged from 0.81 to 0.99. The degradation results together with bioavailable fractions appeared to be consistentwith organic carbon contents in the soils and with volatile fractions of organics. The results indicate that SFE could be a rapid testto predict bioremediation results of composting of PAH-contaminated soils.

A new approach to the direct recovery of polycyclic aromatic hydrocarbons (PAHs) from environmental solid samples has been proposed. It has been shown that rotating coiled columns (RCCs) earlier used mainly in countercurrent chromatography can be successfully applied to the fast continuous-flow extraction of PAHs from soils. A particulate solid sample was retained in the rotating column as the stationary phase under the action of centrifugal forces while a mixture of organic solvents (acetone-cyclohexane, 1:1, v/v) was continuously pumped through. The separation procedure requires less than half an hour, complete automation being possible. No clean-up step is needed before the subsequent HPLC- analysis of extracts. Besides, the dynamic multistage extraction performed in the rotating column at room temperature and normal pressure may have nearly the same efficiency as accelerated batch solvent extraction repeated three times at 150 degrees C and 14 MPa. Contents of PAHs in extracts obtained by using both methods are in good agreement with the certified data on the PAHs concentrations in the soil samples. The use of appropriate "mild" solvents for the dynamic extraction in rotating columns may be very perspective for the simulation of naturally occurring processes and determination of environmentally-relevant forms of PAHs and other pollutants in environmental solids. A particular emphasis could be placed on time-resolved (kinetic) studies of the mobilization of toxicants in soil systems.

To confirm the method for preparing artificially spiked soil with polycyclic aromatic hydrocarbons (PAHs), we tested the homogeneity of PAHs in spiked soils, which were prepared by three different procedures, by using kaolin and ando soil. When the slurry of kaolin and acetone containing PAHs were evaporated by a rotary evaporator at 30 - 35 degrees C, the most homogeneous distribution of PAHs was obtained in the spiked soil. This procedure was applied to the preparation of PAH-spiked soil for natural soil (ando soil). Such spiked soils can be useful as the standard materials for standardization of the analytical methods for PAHs in the soil and sediment samples.

Pressurised liquid extraction (PLE) was applied to the extraction of polycyclic aromatic hydrocarbons (PAHs) from contaminated soils from Husarviken in Stockholm, Sweden. The extraction step was followed by conventional gas chromatography (GC), comprehensive two-dimensional gas chromatography (GC x GC) (both with flame ionisation detection) and gas chromatography-quadrupole mass spectrometry (GC-MS) analysis. Qualitative and quantitative aspects of the results are considered. Qualitatively, results from all chromatographic analyses are in good agreement, and PLE provides a reliable extraction technique with all PAHs extracted in one extraction step; no carry over was observed. With respect to PAH quantification, some variability in results was noted, with better agreement in PAH concentrations for GC and GC x GC measurement, as compared to GC-MS. GC analysis compares favourably with GC x GC apart from the few exceptions where peaks are not fully resolved from other co-extracted analytes, which compromises GC-FID measurement. For example, acenaphthene shows a much higher concentration when measured by GC-FID, demonstrating the superior separating powers of GC x GC; the latter is the preferred technique if precise and accurate quantification of analytes are required. GC-MS results compare reasonably with GC x GC for low-molecular mass PAHs but not for high-molecular mass PAHs; results for GC-MS are consistently higher than those for GC x GC for high-molecular mass PAHs. Since PLE-GC x GC is proposed as a broad screening tool, the demand for precise quantification may be relaxed in the present situation. GC x GC has the added advantage of providing chemical structural information within the two-dimensional contour presentation. Reproducibilities for GC x GC results (peak area) and 2tR were acceptable with relative standard deviations (R.S.D.) of 8 and 1%, respectively (at the mg/kg level), and good repeatability within samples was achieved.

The content and type of polycyclic aromatic hydrocarbons (PAH) in soils from paddy fields and upland areas in South Korea were determined using gas chromatography linked to mass spectrometry (GC-MS). The distribution map of total PAH content was obtained as a contour plot using a geographical information system. The overall distribution of PAH was found to be closely related to the pollution sources, the size of city and the type of industry. The average content of total PAH in all samples was 236 microgkg(-1), and the range was from 23.3 to 2834 microgkg(-1). The highest concentrations were found in soils sampled near iron processing plants. The concentration of PAH decreased in the order fluoroanthene>benzo(b)fluoroanthene>pyrene. Special PAH compound ratios, such as phenanthrene/anthracene and fluoroanthene/pyrene, were calculated to evaluate the origin. The collected data suggested that the pyrogenic origins such as motor vehicle exhaust and heavy industry emission were the dominant source of PAH in Korean soils.

A fast, inexpensive screening method for polycyclic aromatic hydrocarbons in soil has been developed. Using hollow fiber membrane solvent microextraction, 8 microl of octane extraction solvent was placed inside a porous, polypropylene fiber. Following an 8 min analyte preconcentration step, 4 microl of extract was injected into a gas chromatograph. Separation was achieved in less than 10 min with a detection limit of 0.13 mg/kg for 2-methylnaphthalene. Results of both spiked and real soil samples are presented.

This paper describes a new extraction tool for the determination of polycyclic aromatic hydrocarbons (PAHs) in soil and sediment samples, using dynamic microwave-assisted extraction combined with solid-phase extraction (DMAE-SPE). The critical variables for DMAE-SPE are investigated and optimized in an experimental design. The technique proved to be fast, accurate and able to yield quantitative extraction of PAHs from naturally contaminated sediment and soil samples. The set-up is fully automated and features monitored extraction, which facilitates rapid optimization of the method. In addition, only small quantities of solvent and sample are required.

Two developed supercritical fluid extraction (SFE) methods [one for the determination of total petroleum hydrocarbon (TPH) and polychlorinated biphenyls (PCBs), and one for polycyclic aromatic hydrocarbons (PAHs) and creosote components in soil] were evaluated in a Nordic laboratory intercomparison study with 11 participating laboratories. The interlaboratory comparison showed that excellent recoveries can be obtained with SFE for PAHs and PCBs compared to the solvent extraction. For the TPH, the recoveries were significantly higher than those achieved with solvent extraction. The accuracy, expressed as the relative standard deviation, was higher than expected (generally 8-25% for PAHs, 6-20% for PCBs and less than 18% for TPH with a few very high values, especially for PCBs), but not different from the other intercomparison studies. Difference between liquid- and solid-phase collection in SFE was found to be significant only for more volatile PAH components such as naphthalene and fluorene. For PCBs and TPH, there were some variation in the results obtained with the two trapping methods.

A hyphenated HPLC-(1)H NMR method for the identification and quantification of PAHs in soil samples has been developed and applied to a PAH reference sample provided by the Federal Institute for Materials Research and Testing (BAM, Berlin, Germany). The results were compared with those obtained by HPLC-DAD, HPLC-F, and GC-MS analyses of the same sample.

The feasibility of direct-immersion (DI) solid-phase microextraction (SPME) and headspace (HS) SPME for the determination of high-ring polycyclic aromatic hydrocarbons (PAHs) (4- to 6-ring PAHs) in water and soil samples is studied. Three SPME fibers--100- and 30-microm polydimethylsiloxane (PDMS) and 85-microm polyacrylate (PA) fibers-are compared for the effective extraction of PAHs. Parameters affecting the sorption of PAHs into the fiber such as sampling time, sampling volume, and temperature are also evaluated. The extracted amounts of high-ring PAHs decrease with the decreasing of film thickness, and the 100-microm PDMS has the highest extraction efficiency than 85-microm PA and 30-microm PDMS fibers. Also, the extraction efficiency decreases with the increasing molecular weights of PAHs. Of the 10 high-ring PAHs, only fluoranthene and pyrene can reach equilibrium within 120 min at 25 degrees C for DI-SPME in a water sample. Increasing the temperature to 60 degrees C can increase the sensitivity of PAHs and shorten the equilibrium time. A 0.7- to 25-fold increase in peak area is obtained for DI-SPME when the working temperature is increased to 60 degrees C. For HS-SPME, the extraction efficiency of PAHs decrease when the headspace volume of the sampling system increases. All high-ring PAHs can be detected in a water sample by increasing the temperature to 80 degrees C. However, only 4- and 5-ring PAHs can be quantitated in a CRM soil sample when HS-SPME is used. The addition of a surfactant with high hydrophilic property can effectively enhance the sensitivity of high-ring PAHs. HS-SPME as well as DI-SPME with 100-microm PDMS or 85-microm PA fibers are shown to be suitable methods for analyzing high-ring PAHs in a water sample; however, this technique can only apply in a soil sample for PAHs having up to 5 rings.