[New pretreatment method for detecting petroleum hydrocarbons in soil: silica-gel dehydration and cyclohexane extraction].

Oil is a primary source of energy worldwide. However, the use of oil produces large amounts of pollutants, which are detrimental to the environment. The presence of petroleum hydrocarbons in soil is a critical marker of environmental pollution and safety. Rapid on-site detection technology has been broadly used in emergency tracking, offering critical information support for effective reactions to environmental emergencies. Thus, it is expected to play an increasingly critical role in environmental remediation efforts. The current approach for petroleum hydrocarbon detection in soil mainly involves Soxhlet extraction with a combination of solvents, including acetone and n-hexane. The samples are then analyzed after rotary evaporation, dehydration with anhydrous sodium sulfate, and purification using a magnesium silica-type adsorbent. Unfortunately, this approach requires sample analysis to be performed in the laboratory, which is tedious and time consuming, and consumes large amounts of solvents. Moreover, the rotary evaporator is not portable. Therefore, this method is not appropriate for the rapid on-site detection of petroleum hydrocarbons. In this study, a rapid on-site detection method based on silica-gel dehydration and cyclohexane extraction was developed for the extraction and pretreatment of petroleum hydrocarbons (C10-C40) in soil. First, an appropriate amount of silica gel was added to the soil, and the mixture was completely ground to eliminate moisture. Next, petroleum hydrocarbons were extracted with 40 mL of cyclohexane, and the extract was cleaned by Florisil solid-phase extraction (SPE) column elution. Finally, the samples were analyzed by gas chromatography (GC) to evaluate the above method. The silica gel exhibited optimal adsorption properties compared with anhydrous sodium sulfate, calcium oxide, and molecular sieves, with recovery of 87.5%. The effects of different soil water content (5%, 10%, and 20%) and silica gel (1, 3, 5, and 10 times the moisture content) dosage on the extraction of petroleum hydrocarbons were investigated. The recoveries of petroleum hydrocarbons increased from 74.0% to 103.8% after 15 min of invasive extraction (relative standard deviation, RSD, <10.1%) when silica gel amounting to 10 times the moisture content was used. Five types of silica gels with different properties were purchased from four manufacturers, and the effects of these silica gels on the dehydration and extraction efficiency of petroleum hydrocarbons in soil were assessed. The results showed that amorphous silica gel led to low recoveries (<60%), spherical silica gel achieved extraction efficiencies of approximately 70%-90%, and alkaline silica gel produced recoveries with poor precision. Therefore, neutral spherical silica gel was used for further experiments. The fingerprints of petroleum hydrocarbons with different carbon numbers are an important reference for identifying pollution sources. Thus, ensuring good recoveries throughout the entire carbon range is necessary to ensure the accuracy of the fingerprint analysis results. The proposed method showed good recoveries for petroleum hydrocarbons of all carbon numbers (75%-101%). The findings above indicate that the developed method could be an efficient means to extract petroleum hydrocarbons from soil for both total quantity and fingerprint analyses. Compared with standard methods, the proposed method requires lower solvent dosages and features simpler processing steps. Another advantage of this method is that it does not require the use of highly toxic halogenated solvents; thus, it does not contribute to environmental pollution. It can be applied to the laboratory analysis of soil petroleum hydrocarbons and coupled with other rapid on-site detection techniques for soil petroleum hydrocarbons, such as infrared spectroscopy and portable GC. However, because it does not include a concentration process, the developed method exhibits relatively low sensitivity. In the future, we plan to develop a simple and flexible on-site sample-concentration system to further improve various indicators of this method.

Current analysis strategies of polychlorinated naphthalenes in soil and their application in occurrence and distribution investigation: A mini-review.

As a new kind of persistent organic pollutants, polychlorinated naphthalenes (PCNs) have been paid much attention owing to the environmental and health hazards. Several countries have announced moves to intensify its battle against these new pollutants to improve environmental protection. Due to the matrix complexity of soil and the low-level of targets, PCNs analysis requires ongoing development to improve the sensitivity and accuracy. The effective extraction technique that allows for their separation from interfering substances and sensitive analysis instrument that possesses low detection limits are all important parts for the analytical procedure. This review focused on the dissemination of the latest advances covering sample pretreatment and instrumental analysis methods, followed by their application in investigating the occurrence and homologues distribution of PCNs in soil. It will help readers quickly understand the PCNs analysis methods, and choose the appropriate one according to their objects and laboratory conditions, which may conduce to the supervision and treatment of new pollutions.

Multi-omics analysis to reveal disorders of cell metabolism and integrin signaling pathways induced by PM2.5.

Atmospheric fine particle pollution is known to cause many adverse health effects. However, the potential mechanisms of PM2.5-induced cytotoxicity still needs further understanding. Herein, we integrated cytotoxicity, component profiling, metabolomics and proteomics data to deeply explain the biological responses of human bronchial epithelial cells exposed to PM2.5. We observed that PM2.5 caused cell cycle arrest, calcium influx, cell damage and further induced cell apoptosis. The contents of heavy metals and 4-6 rings PAHs in PM2.5 were positively correlated with intracellular ROS, indicating that they might be the important components to induce the above cytotoxicity. Integrated metabolomics and proteomics analysis revealed the significant alterations of many metabolic processes, such as glycolysis, the citric acid cycle, amino acid metabolism and lipid metabolism. Notably, we found that PM2.5 inhibited the integrin signaling pathway, including down-regulating the protein expression of integrins and the phosphorylation of downstream signaling kinases, which might ultimately affect cell cycle progression, cell metabolism and apoptosis. This study provided a comprehensive data resource for the deep understanding of biological toxicity mechanisms caused by atmospheric fine particles in human lung-bronchial epithelium cells.

[Evaluation of thermal adsorption and desorption properties of dioxins on 11 adsorbents].

The key to the online thermal capture of dioxins is the appropriate choice of adsorbent for efficient capture at low temperatures and rapid desorption at high temperatures. Efficient adsorbents can allow for capture and separation during the online monitoring of dioxins or during offline dioxin tests. In this study, 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD) and pentachlorodibenzofuran (1,2,3,8,9-PCDF) were used as model compounds for dioxin monomers, and an electron capture detector (ECD) was used to detect the dioxin signals. The retention volumes of 1,2,3,4-TCDD and 1,2,3,8,9-PCDF on 11 types of adsorbents were determined using a packed-column gas chromatography system. Then, the corresponding van der Hoff equation was established, and these adsorbents were evaluated for the thermal trapping of dioxin. The linear coefficients of determination (R2) of these adsorbents were greater than 0.96, which indicated a strong correlation between the adsorption capacity and 1/T (T: temperature). The gas-solid partition coefficients (KSA) of the adsorbent at 120, 150 and 180 ℃ were predicted according to the van der Hoff equation, which was obtained in an earlier study. Among the 11 adsorbents, florite had the largest adsorption capacity at 120, 150, and 180 ℃, especially at 120 ℃; the KSA values for 1,2,3,4-TCDD and 1,2,3,8,9-PCDF on florite were as high as 1.82×108 m3/g and 1.46×1013 m3/g, respectively. Carbon-based adsorbents of the Chinese stilbene polymer porous microspheres GDX series, GDX-101, GDX-102, GDX-103, GDX-105, and GDX-203, can facilitate thermal desorption below 270 ℃, which is the maximum tolerance temperature for series 1 and 2, thus providing evidence for the feasibility of using these adsorbents for the thermal adsorption/desorption of dioxins. When the detection temperature is less than 310 ℃, 1,2,3,4-TCDD is thermally desorbed from mordenite, but 1,2,3,8,9-PCDF is not; this indicates the selective adsorption of dioxin monomers on zeolite. However, diatomite and montmorillonite have poor adsorption capacity for dioxins in the gas phase, thus being unsuitable for the thermal trapping of dioxins. Florite, silica gel, alumina, GDX-102, GDX-103, and GDX-203, which have strong adsorption capacities, were selected as possible absorbents for the next evaluation. Comparison of the lnKSA values of dioxin monomers on the same adsorbent at 120 ℃ and 270 ℃ revealed that the retention volume of florite was the largest at both temperatures. When the thermal trapping performance of dioxin at low temperatures is considered, florite is thought to be the best among the 11 adsorbents for capturing dioxins. However, when the desorption performance at high temperatures is considered, GDX-102 is the best adsorbent for the thermal desorption of dioxins, and its lnKSA,270 ℃ is the smallest among those for the aforementioned six adsorbents. The lnKSA,120 ℃ and lnKSA,270 ℃ values of silica gel, GDX-103, and GDX-203 are similar to those of GDX-102, and hence, they can also be used as rapid thermal adsorption/desorption materials. In this study, the thermal adsorption/desorption properties of 1,2,3,4-TCDD and 1,2,3,7,8-PCDF on 11 adsorbents were systematically evaluated to obtain a new solution for the sampling and preparation of dioxins and to provide technical support for the thermal capture of dioxins. It should be noted that these results were obtained under ideal conditions of nitrogen, without considering the influence of the complex conditions of flue gas (such as moisture and CO2) on the thermal capture. To achieve the thermal capture of dioxins in incineration flue gas, it is necessary to carry out the relevant evaluation and test research in a flue gas atmosphere.

The dose effect of dansyl chloride on the derivative products of bisphenols and its application for the determination of bisphenols in human serum by high-performance liquid chromatography-tandem mass spectrometry.

Human exposure to bisphenols has rarely been reported. The most important challenges in this regard are the sensitivity and accuracy of the analytical methods employed. Dansyl chloride derivatization prior to high-performance liquid chromatography-tandem mass spectrometry has been prevalently employed to improve sensitivity. However, the dose effect of the derivatization reagent on the reaction products is not well understood, especially for reactants with two or more active groups. This study investigated the mass ratio of dansyl chloride to bisphenols and found the mass ratio played a vital role in changing the composition of derivatives; further, the optimal ratio for obtaining di-substituted derivatives was confirmed. Under optimal conditions, solid-phase extraction followed by dansyl chloride derivatization coupled with high-performance liquid chromatography-tandem mass spectrometry was used to detect eight bisphenols in human serum samples. The method detection limits of the eight bisphenols were 0.025-0.28 ng/mL, and the recoveries were 72.9-121.7% by spiking bisphenols (2, 5, and 20 ng/mL) into bovine serum. The detection frequencies of bisphenol A and bisphenol F in 73 serum samples obtained from children from Guangzhou were 41.1% and 71.2%, respectively, while the detection frequencies of other bisphenols were below 20%. The concentrations of bisphenol A and bisphenol F were < 0.28-8.0 ng/mL and < 0.028-7.6 ng/mL, respectively.

The effect of toxic components on metabolomic response of male SD rats exposed to fine particulate matter.

PM2.5 pollution was associated with numerous adverse health effects. However, PM2.5 induced toxic effects and the relationships with toxic components remain largely unknown. To evaluate the metabolic toxicity of PM2.5 at environmentally relevant doses, investigate the seasonal variation of PM2.5 induced toxicity and the relationship with toxic components, a combination of general pathophysiological tests and metabolomics analysis was conducted in this study to explore the response of SD rats to PM2.5 exposure. The result of general toxicology analysis revealed unconspicuous toxicity of PM2.5 under environmental dose, but winter PM2.5 at high dose caused severe histopathological damage to lung. Metabolomic analysis highlighted significant metabolic disorder induced by PM2.5 even at environmentally relevant doses. Lipid metabolism and GSH metabolism were primarily influenced by PM2.5 exposure due to the high levels of heavy metals. In addition, high levels of organic compounds such as PAHs, PCBs and PCDD/Fs in winter PM2.5 bring multiple overlaps on the toxic pathways, resulting in larger pulmonary toxicity and metabolic toxicity in rats than summer.

Mass balance and elimination mechanism of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during the kraft pulping process.

Papermaking raw materials are usually digested by NaOH and Na2S solution. The fate of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during the kraft pulping process is still poorly known. In this study, a comprehensive investigation was conducted on the variation in PCDD/Fs in the kraft pulping section of 3 modern non-wood pulp mills adopting elemental chlorine-free (ECF) bleaching technology. Similar dioxin homologue profiles, dominated by Cl1-3DF and Cl2DD homologues, were observed in the raw materials, black liquors and brown pulps; and the partitioning behaviors of dioxin congeners between black liquor and brown pulp were found to be partly dependent on their octanol-water partitioning coefficients. Dioxin mass flow analysis indicated that the raw materials contributed more than 95 % to the dioxins entering the pulping section. Approximately 7 - 30 % of the input dioxins were exported by black liquor, and the brown pulp carried 44 - 51 % of the input dioxins into the subsequent bleaching section. The kraft pulping process caused a 40 - 48 % reduction in input dioxins. Alkaline hydrolysis and coupling reaction between dioxins and the aromatic fragments of lignin were proposed as two most possible mechanisms for dioxin elimination. In general, modern pulp mills have actually become industrial plants that eliminate environmental dioxins.

Mechanistic aspects of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) formation from chlorine bleaching of non-wood pulp.

Chlorine bleaching of non-wood pulp can produce and release polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) into environment. In this study, a series of chlorination experiments were conducted to explore the source, formation pathway and formation kinetics of Cl1-8DD/Fs during the chlorine bleaching of wheat straw pulp. The 13C isotope-labeling experiment verified that PCDD/Fs could not be formed from the chlorination of phenols in pulp. Above 80% of the observed PCDFs originated from the direct chlorination of dibenzofuran (DBF) in unbleached wheat straw pulp, while approximately 60% of the observed PCDDs came from the chlorination of nonextractable precursors in the pulp. The yield of total PCDFs was 2 orders of magnitude higher than that of total PCDDs. The kinetic study indicated that DBF was more easily chlorinated than dibenzo-p-dioxin (DBD) in the pulp solution. Pseudo-first-order reaction kinetic equations fitted the formation and degradation of PCDD/Fs well. The direct chlorination of DBD/F primarily preferred a selective pattern at the 2 position, followed by the 8, 7 and 3 positions. A higher content of DBF in unbleached pulp led to a higher yield of 2,3,7,8-Cl4DF. Finally, the practical implication for dioxin formation control was discussed.

Hazy Weather-Induced Variation in Environmental Behavior of PCDD/Fs and PBDEs in Winter Atmosphere of A North China Megacity.

Haze is a serious pollution problem during the wintertime in North China. In this study, we investigated how the periodic cycle of winter haze events affect the environmental behaviors of two typical persistent organic pollutants, namely, polychlorinated dibenzo- p-dioxins and dibenzofurans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs), in the atmosphere of a typical megacity, Beijing. The average atmospheric concentrations of the total di- to octa-CDD/Fs (∑PCDD/Fs: 378.0 pg/m3) and the total mono- to nona-BDEs (∑9hPBDEs: 166.5 pg/m3) during haze episodes increased by 3.6-fold and 1.9-fold compared with those during the nonhaze periods, respectively; and their concentrations both linearly increased with PM2.5 levels and decreased as a power function of the atmospheric boundary layer height. The elevated concentrations could be clearly attributed to the vertically sinking motion of airflow in the midlower troposphere. When a haze event occurred, the partitioning rate of PCDD/Fs and PBDEs into particles was reduced; the largest fraction of the particle-bound ∑PCDD/Fs was shifted from ultrafine particles to accumulation mode particles; and a steady-state model (Li-Ma-Yang model) satisfactorily described the gas-particle partitioning of the PCDD/F and PBDE homologues. The inhalation exposure risk evaluation indicated that special attention should be paid to the increased cancer risk induced by the elevated inhalation intake of PCDD/Fs during haze episodes.

Polychlorinated dibenzo-p-dioxin and dibenzofuran precursors and formation mechanisms during non-woodpulp chlorine bleaching process.

There is great concern about decreasing the amounts of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) that are formed and emitted during the chlorine bleaching of pulp. The formation of PCDD/Fs during non-woodpulp chlorine bleaching was investigated in the study described here. Wheat straw was separated into three components, cellulose, hemicellulose, and lignin. Chlorination experiments were performed, and lignin and hemicellulose contributed more than cellulose to PCDD/F formation when the pulp was bleached using chlorine. The chemical components of lignin were identified by gas chromatography mass spectrometry, and nine possible PCDD/F precursors were quantified by gas chromatography tandem mass spectrometry. Spiked chlorination experiments were performed to investigate the effects of these compounds on PCDD/F formation. 4-Ethyl-2-methoxyphenol had the strongest effect on PCDD/F formation, followed by p-chlorophenol, and guaiacol. All the test compounds promoted polychlorinated dibenzofuran formation but had limited effects on polychlorinated dibenzo-p-dioxin formation. The results allowed mechanisms for the formation of PCDD/Fs from phenol, chlorophenol, catechol, and guaiacol to be proposed.

Spatial variation of PCDD/F and PCB emissions and their composition profiles in stack flue gas from the typical cement plants in China.

Cement production processes are important sources of unintentionally produced persistent organic pollutants (UP-POPs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs). The emissions of PCDD/Fs and PCBs in the stack flue gases from eight typical cement plants in China were investigated in this study, including one wet process rotary kiln, three dry process rotary kilns and four vertical shaft kilns. PCBs exhibited relatively higher mass concentrations with the dioxin-like (dl) and indicator PCBs of 0.14-17.36 and 0.42-12.90 ng/Nm3, respectively. However, PCDD/Fs contributed most to the total toxic equivalent concentrations, with the proportions exceeding 90%. The international toxicity equivalency (I-TEQ) concentrations of PCDD/Fs varied greatly from 0.01 to 0.46 ng I-TEQ/Nm3 in stack gases, two of which exceeded the exhaust gas concentration limit of 0.1 ng I-TEQ/Nm3 established by the European Union Directive. In weight units, 1,2,3,4,6,7,8-HpCDF was the most abundant congener in the stack gases from various types of cement kilns, with the factions of 17.0-27.8%. TCDFs and PeCDFs were the first two most abundant homologue groups. 2,3,4,7,8-PeCDF was the largest contributor to the total I-TEQ. The emission factors of PCDD/Fs and PCBs in the eight cement kilns were estimated to be 0.01-1.35 µg I-TEQ/t clinker and 8.20 × 10-4∼8.23 × 10-2 µg World Health Organization TEQ (W-TEQ)/t clinker, respectively. No obvious differences of the PCDD/F and PCB emission factors were found among the varied cement production technologies.

Phenyltrichlorosilane-functionalized magnesium oxide microspheres: Preparation, characterization and application for the selective extraction of dioxin-like polycyclic aromatic hydrocarbons in soils with matrix solid-phase dispersion.

Magnesium oxide microspheres functionalized with phenyltrichlorosilane (PTS-MgO) were synthesized by surface modification through silanization reaction, which was confirmed by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry analysis (TGA) and N2 adsorption-desorption. The result indicated that PTS-MgO not only possessed the ability of enhancing the retention with PAHs, but also weakening the interference from chlorinated compounds. As a sorbent for the matrix solid-phase dispersion (MSPD) extraction, PTS-MgO was used to selectively extract seven dioxin-like polycyclic aromatic hydrocarbons (DL-PAHs) from soil samples. Various parameters affecting the recoveries of seven DL-PAHs were investigated and optimized, such as sorbent/sample mass ratio, grinding time, rinsing and eluting conditions. Under the optimized conditions, the developed method combining MSPD with HPLC-FLD exhibited good sensitivity (0.02-0.12 ng g-1 detection of limits) and linearity (linear correlation coefficient greater than 0.9997). Satisfactory recoveries with DL-PAHs spiked at two levels (10 and 80 ng g-1) were obtained in the range of 72.2-113.1% with RSD < 9.6%, indicating that PTS-MgO had a potential in MSPD extraction of DL-PAHs in soils. Additionally, the proposed MSPD-HPLC-FLD method was also verified by detecting seven DL-PAHs in the standard reference soil. Based on the developed method, DL-PAHs in soil samples were detected with the concentration ranging from 70.08 to 555.05 ng g-1 dry weight (dw). The total toxic equivalency quotients (TEQ) of seven DL-PAHs varied from 9.93 to 143.94 ng TEQ/g dw.

Concentrations of short- and medium-chain chlorinated paraffins in indoor dusts from malls in China: Implications for human exposure.

Levels and distribution of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) were measured in indoor dusts from malls in China. The concentrations of SCCPs and MCCPs in dustfalls from a building material mall ranged from 6.0 to 361.4 µg g-1 and from 5.0 to 285.9 µg g-1, respectively. Much heavier contamination was found in central air conditioner filter (CACF) dusts from a newly opened shopping mall, with SCCP concentrations of 114.7-707.0 µg g-1 and MCCP concentrations of 89.0-1082.9 µg g-1. The C13- and C14-CPs were the dominant congeners, while the Cl7 and Cl8 groups were the major chlorine congeners in both kinds of dust samples. Significant correlation relationships (p ≤ 0.05) were found between ∑SCCPs and ∑MCCPs in CACF dusts and dustfalls. Varied exposure pathways including dust ingestion and dermal permeation have been evaluated. The average daily exposure doses of SCCPs and MCCPs for the adult in CACF dusts and dustfalls were estimated to be 0.394 and 0.150 µg kg-1 day-1, respectively. The toddler had higher exposure risks with 5.918 and 2.658 µg kg-1 day-1 in the shopping and building material malls, respectively. Dermal permeation was the predominated exposure pathway for the adult, while dust ingestion was suggested to be more important for the toddler due to hand-to-mouth contact.

Bioaccumulation of organochlorine pesticides and polychlorinated biphenyls by loaches living in rice paddy fields of Northeast China.

The concentrations of 21 organochlorine pesticide (OCP) residues and 18 polychlorinated biphenyl (PCB) congeners were measured in two loach species (Misgurnus mohoity and Paramisgurnus dabryanus) and the soils of their inhabiting rice paddies from three typical rice production bases of Northeast China to explore the main factors influencing the bioaccumulation. The concentrations of ∑18PCBs and ∑21OCPs in loaches were determined to be in the ranges of 0.14-0.76 ng g(-1) wet weight (ww) and 1.19-78.53 ng g(-1) ww, respectively. Most of loaches showed the considerably high contamination levels of dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), which accounted for over 97% of the total OCPs. The much lower maximum allowable loach consumption rates (<15 g d(-1)) indicated a high carcinogenic risk that results from the consumption of rice-field loaches. The field biota-soil accumulation factor (BSAF) was calculated as a main measure of bioaccumulation potential. The comparisons of BSAF values and the results of multivariate analysis indicated that habitat-specific environmental conditions, mainly the paddy soil contamination levels and average temperature, decisively affected the bioaccumulation of organochlorine contaminants. When the influence of lipid contents was offset, M. mohoity loaches were found to have a higher potential to accumulation PCBs and OCPs than P. dabryanus loaches, while the bioaccumulation potentials did not exhibit significant differences between juvenile and adult loaches and between male and female loaches. The octanol-water partition coefficient (KOW) was the main chemical factor influencing bioaccumulation potentials. The BSAF values presented an increasing tendency with increasing log KOW values from 6.0 to approximately 7.0, followed by a decreasing tendency with a continuous increase in log KOW values. Moreover, loaches exhibited an isomeric-selective bioaccumulation for p,p'-chlorinated DDTs, α-HCH, ß-HCH, δ-HCH and cis-chlordane.

High performance solid-phase extraction cleanup method coupled with gas chromatography-triple quadrupole mass spectrometry for analysis of polychlorinated naphthalenes and dioxin-like polychlorinated biphenyls in complex samples.

A solid-phase extraction (SPE) cleanup method was developed to purify the sample extracts for the analysis of polychlorinated naphthalenes (PCNs) and dioxin-like polychlorinated biphenyls (dl-PCBs). Monodisperse magnesium oxide (MgO) microspheres and basic alumina were used as SPE adsorbents. Important parameters of the SPE procedure were optimized, including the amount of basic alumina and the type and volume of the washing and elution solvents. The optimized SPE cleanup method exhibited excellent purification performance for the removal of organochlorinated compounds, lipid compounds, sulfur, and pigments. Additionally, it was found that the retention activities of congeners differed with the number and position of the chlorine substituents in PCNs. In this study, an analytical method based on a combination of accelerated solvent extraction (ASE) coupled with SPE cleanup and gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) is proposed for the analysis of PCNs and dl-PCBs in complex samples (sediment, pine needle, and scallop samples). The analytical method demonstrates good linearity, acceptable recovery (63-148%) and precision (relative standard deviations less than 26%). The limits of detection (LODs) of PCN and dl-PCB congeners were in the range of 0.6-19.1pgg(-1) and 0.4-8.6pgg(-1), respectively. The PCNs and dl-PCBs levels in these samples ranged from 0.16 to 3.07ngg(-1) dry weight (dw) and from undetectable to 0.07ngg(-1) dw, respectively.

Occurrence, distribution and source apportionment of polychlorinated naphthalenes (PCNs) in sediments and soils from the Liaohe River Basin, China.

The occurrence and spatial distribution of polychlorinated naphthalenes (PCNs) were investigated in sediments, upland and paddy soils from the Liaohe River Basin. Concentrations of ΣPCNs were in the range of 0.33-12.49 ng g(-1) dry weight (dw) in sediments and 0.61-6.60 ng g(-1) dw in soils, respectively. Tri-CNs and tetra-CNs were the dominating homologues. An increasing trend of PCNs contamination was found in sediments with the rivers flowing through industrial areas and cities. Soils collected near cities exhibited higher abundance of PCNs than that of rural areas. The distribution of PCNs was related to the local industrial activities, rather than total organic carbon. Positive matrix factorization (PMF) was used for the source apportionment of PCNs in sediments and paddy soils. The result of PMF indicated that PCNs in sediments and paddy soils were mainly from the industrial processes, with additional contributions from the historical use of Halowax 1014 and atmospheric deposition.

Kinetics of PCDD/Fs formation from non-wood pulp bleaching with chlorine.

Chlorine bleaching is still practiced by most of nonwood pulp and paper mills, resulting in a considerable amount of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) formation and emission. In this study, the effects of primary chlorination conditions on the formation of PCDD/Fs from nonwood pulp bleaching with elemental chlorine were investigated. It was found that low-chlorinated PCDD/Fs were usually formed and then underwent further chlorination to form highly chlorinated PCDD/Fs with increasing chlorination time. Higher available chlorine dosages and lower system pH values greatly accelerated dioxin formation, and pH 3 was the threshold for the formation of tetra- to octa-CDD/Fs. Higher temperatures promoted the formation of lower-chlorinated PCDD/Fs, while caused significant reduction of tetra- to hepta-CDDs and penta- to octa-OCDFs. PCDFs were formed much faster than PCDDs. A first-order kinetic model showed a good fit to the data for tetra- to oct-CDFs formation under different chlorination conditions, indicating that chlorine substitution was the rate determining step for their formation. Finally, the optimum chlorination conditions for minimizing and eliminating the formation of 2,3,7,8-TCDD/TCDF in nonwood pulp bleaching with elemental chlorine were established.

Simultaneous monitoring of PCB profiles in the urban air of Dalian, China with active and passive samplings.

The concentration of polychlorinated biphenyls (PCBs) in the urban air of Dalian, China was monitored from November 2009 to October 2010 with active high-volume sampler and semipermeable membrane device (SPMD) passive sampler. The concentration of PCBs (particle + gas) (SigmaPCBs) ranged from 18.6 to 91.0 pg/m3, with an average of 50.9 pg/m3, and the most abundant dioxin-like PCB (DL-PCBs) was PCB118. The WHO-TEQ values of DL-PCBs were 3.6-22.1 fg/m3, with an average of 8.5 fg/m3, and PCB126 was the maximum contributor to SigmaTEQ. There was a much larger amount of PCBs in the gas phase than in the particulate phase. The dominant PCB components were lower and middle molecular weight PCBs. With increasing chlorination level, the concentration of the PCB congeners in the air decreased. The gas-particulate partitioning of PCBs was different for the four seasons. The gas-particulate partitioning coefficients (logKp) vs. subcooled liquid vapor pressures (logP(L)0) of PCBs had reasonable correlations for different sampling sites and seasons. The absorption mechanism contributed more to the gas-particulate partitioning process than adsorption. Correlation analysis of meteorological parameters with the concentration of PCBs was conducted using SPSS packages. The ambient temperature and atmospheric pressure were important factors influencing the concentration of PCBs in the air. The distribution pattern of the congeners of PCBs and the dominant contributors to DL-PCBs and TEQ in active samples and SPMDs passive samples were similar. SPMD mainly sequestrated gas phase PCBs.

Formation and emission of PCDD/Fs in Chinese non-wood pulp and paper mills.

Chlorine bleaching is still practiced by non-wood pulp and paper mills in China, resulting in considerable formation and emission of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). We investigate the distribution of PCDD/Fs in different papermaking processes and dioxin emissions at six typical Chinese non-wood pulp and paper mills. Raw materials for papermaking included reed, wheat straw, bamboo, and sugar cane bagasse. The formation and emission of PCDD/Fs varied strikingly according to bleaching processes and raw materials. Elemental chlorine bleaching promoted the formation of tetra- to octa-CDDs and 2,3,7,8-TCDF, while hypochlorite bleaching only gave rise to a significant increase of 2,3,7,8-TCDF. Bleaching with elemental chlorine and hypochlorite increased 2,3,7,8-TCDF 0.9-42.5 and 0.3-4.1 times, respectively. Most of the 2,3,7,8-TCDF formed at hypochlorite bleaching stage was partitioned into the effluent, which indicated that hypochlorite bleaching was also an important emission source of dioxins. The removal of PCDD/Fs occurred visibly during alkaline digestion, alkaline extraction, and hydrogen peroxide bleaching. Furthermore, the annual emission of PCDD/Fs from Chinese non-wood pulp and paper mills was evaluated.

A new cleanup method of dioxins in sediment using large volume injection gas chromatography online coupled with liquid chromatography.

A new cleanup method was developed and validated for the determination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in sediment. The sample extract was first treated with sulfuric acid and then cleaned up by a large volume injection gas chromatography online coupled with liquid chromatography (LVI-GC-LC) system. PCDD/Fs in the extract were separated by a GC column (DB-5), selected cut, cool trapped and transferred to a LC column (alumina). The fraction of PCDD/Fs eluted from the alumina column was collected and concentrated for the instrumental analysis. Under the optimized conditions, LVI-GC-LC method achieved the recoveries of 57-102% for 2,3,7,8-substituted PCDD/Fs, which met the requirements of US Environmental Protection Agency (EPA) Method 1613 and were better than those obtained using the conventional multistep column cleanup method. Meanwhile, compared with the conventional method, the limit of detection (LOD) values of 2,3,7,8-substituted PCDD/Fs cleaned up by LVI-GC-LC method were decreased due to the high-efficiency removal of interferents. These results suggested that the LVI-GC-LC cleanup method was a promising alternative to the multistep cleanup procedure for the determination of dioxins in environmental samples.