The fly ash from waste incineration poses a serious threat to human health due to its high content of dioxins.Hydrothermal treatment is an efficient and clean method on the decomposition and detoxifying of fly ash.To ...The fly ash from waste incineration poses a serious threat to human health due to its high content of dioxins.Hydrothermal treatment is an efficient and clean method on the decomposition and detoxifying of fly ash.To study the degradation mechanism of dioxins,this paper uses molecular dynamics(MD)to simulate the hydrothermal reaction process of polychlorinated dibenzo-p-dioxins(PCDDs)under different conditions,and the degradation mechanism of PCDDs is obtained.The results show that the degradation of PCDDs includes two pathways:the first pathway is the substitution of Cl groups by hydroxyl groups to form low-chlorine substitution products through direct hydrogenation,and the second pathway is the formation of non-toxic benzene ring structures accompanied by the cleavage of C—O bonds.The two degradation pathways of PCDDs well explain the changes in toxicity before and after the hydrothermal treatment of fly ash,which is consistent with experimental results.This study provides theoretical guidance for the harmless treatment process of fly ash via hydrothermal method.展开更多
Dioxins, which are of the most toxic materials on the earth, are principal emitted from waste incineration process. The molecular structures, toxicity parameters, such as toxicity equivalency factor, tolerable daily i...Dioxins, which are of the most toxic materials on the earth, are principal emitted from waste incineration process. The molecular structures, toxicity parameters, such as toxicity equivalency factor, tolerable daily intake and physic-chemical properties of dioxins are briefly summarized. Three formation mechanisms of dioxins in waste incineration process, namely as de novo synthesis, mechanisms involving small organic molecular as precursors and homogenous gas phase reaction mechanism are alto reviewed. The influencing factors for dioxins formation during waste incineration process are also discussed. Three major methods for reducing dioxins emission from waste incineration process are discussed based upon the formation mechanisms and influencing factors. A new waste incineration process with low dioxins emission and low hydrogen chloride corrosion has been proposed based on multi- stage unit operation principal according to formation mechanisms of dioxins and potential production location in waste incinerators.展开更多
The ambient air in vicinity of different industrial sources for PCDD/PCDFs was sampled by TSP/PM10 active samplers and passive PUF disk samplers in Tangshan City, a metropolis containing clusters of various industrial...The ambient air in vicinity of different industrial sources for PCDD/PCDFs was sampled by TSP/PM10 active samplers and passive PUF disk samplers in Tangshan City, a metropolis containing clusters of various industrial plants. The TEQ concentrations of PCDD/PCDFs ranged from 44.2 to 394.1 fg I-TEQ/m^3 with an average of 169.9 fg I-TEQ]m^3. 2,3,4,7,8-PeCDF was the dominant contributor to ∑TEQ, contributing 41% （12% to 55%）, while 1,2,3,4,6,7,8-HpCDE OCDD and OCDF were the major congeners for the total concentrations. The ratios of ∑PCDF/∑PCDD reached 2.54 on average, suggesting that de novo synthesis in thermal processes played an important role to the airborne pollution of PCDD/PCDFs. The similarities congener profiles indicated that TSP and PM10 active sampling methods are comparable for the determination of the PCDD/PCDFs in ambient air, and the ratios of concentrations determined by the two methods suggested that the PCDD/PCDFs tended to stay in fine particles. It was found that 2,3,7,8-TCDF and OCDD were the dominating congeners in the passive PUF disks samples. Through principal components analysis, the coke industry was suggested to be a relatively high potential emission source for PCDD/PCDFs in the ambient air of Tangshan, which was possibly formed by de novo synthesis mechanism. In this study, the atmospheric impacts to the environment from different industrial sources could be ranked as follows （from high to low）： coking, iron sintering, steel making, power generation and chlorinate alkali chemical production industries.展开更多
Bulk（wet and dry） deposition samples were collected in Saitama Prefecture, Japan throughout a year（February 8, 2012 to February 7, 2013） to estimate the influence of dioxins emitting from waste incinerators on riv...Bulk（wet and dry） deposition samples were collected in Saitama Prefecture, Japan throughout a year（February 8, 2012 to February 7, 2013） to estimate the influence of dioxins emitting from waste incinerators on river water quality. The annual deposition flux of dioxins was 3.3 ng-toxic equivalent（TEQ）/m^2/year. Source identification using indicative congeners estimated that 82% of dioxin TEQ in the bulk deposition（2.7 ng-TEQ/m^2/year）was combustion-originated, indicating that most of the dioxins in the deposition were derived from waste incinerators. In Saitama prefecture the annual flux of combustionoriginated dioxins in depositions was apparently consistent with that of dioxin emission into the air from waste incinerators. The TEQ of combustion-originated dioxins in the deposition per rainfall was 2.4 pg-TEQ/L on annual average, exceeding the environmental quality standard（EQS） for water in Japan of 1 pg-TEQ/L. This suggests there is a possibility that dioxins in atmospheric deposition have a significant influence on the water quality of urban rivers which rainwater directly flows into because of many paved areas in the basins.The influence of combustion-originated dioxin in the deposition on the water quality of Ayase River, an urban river heavily polluted with dioxins, was estimated at 0.29 pg-TEQ/L on annual average in 2015. It seems that dioxins in atmospheric deposition from waste incinerators have a significant influence on water quality of some urban rivers via rainwater though the dioxins in the ambient air have achieved the EQS for atmosphere at all monitoring sites in Japan.展开更多
Loaded on the cordierite, the rare earth doped composite catalyst was prepared by sol-gel method combined with dipping technique. Taking Orthodichlorobenzene as model, the catalyst was used to remove the dioxins of th...Loaded on the cordierite, the rare earth doped composite catalyst was prepared by sol-gel method combined with dipping technique. Taking Orthodichlorobenzene as model, the catalyst was used to remove the dioxins of the waste gas. The results showed that at 280 ℃ and gas space velocity being 8000 h-1, the orthodichlorobenzene could be removed effectivily by the prepared CeO-TiO2-V2O5 composite catalyst whose activity was remarkably enhanced by the doping of Ce, while the industrial side-stream test of dioxins from refuse incineration smoke indicated that the decomposition rate could reach above 93% under the same conditions.展开更多
Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Mana...Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Managing the release of these chemicals is therefore important. The Stockholm Convention on Persistent Organic Pollutants requires parties to adopt measures that reduce sources of these chemicals. Sierra Leone developed its National Implementation Plan (NIP) in 2008, in compliance with this requirement. However, no known further steps have been taken, particularly at community level. In 2013, the UNDP’s GEF/SGP funded a pilot project to manage the release of Dioxins and Furans from two dumpsites in Freetown, Sierra Leone. This work was sponsored with funds from that project. The work sought to delineate the exposure of communities within and around the Bormeh-Kingtom dumpsite (Kingtom, Kolleh town, Ascension town, Crab town, and Congo town) to the chemicals. The study considered sources of exposure, relative quantities generated per year, and the routes of exposure. This exposure study is a first step in managing the release from those sources. Enumerators deployed at the dumpsite every day, 7:00 AM to 6:00 PM, for three months, quantifying and recording source materials. The amount of source materials dumped per day informed calculation of Dioxin/Furan releases in grams toxicity equivalence per year. The results revealed a release of 128.914 g TEQ/year in air and residue. This implies that the communities are at high risk of inhalation and dermal exposure. Livestock, mainly pigs, are also exposed as they feed on the waste deposited in the dumpsite. Humans in turn feed on the livestock, a recipe for biomagnification. The project team has been working on developing Best Management Practices to suppress the release of the chemicals.展开更多
The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed. The influence of temperature change on the...The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed. The influence of temperature change on the PCDD/Fs emission from the sintering process and the formation mechanism of PCDD/Fs were discussed. The result has shown that among the seventeen gaseous and particle-bound PCDD/Fs in the flue gas of different windboxes, furans occupied the major place. The proportion of the gaseous PCDD/Fs in most windboxes is from 40% to 60%. The change tendencies of the concentration of both the gaseous and particle-bound PCDD/Fs were similar, with a higher level at the end of the sintering bed. The PCDD/Fs concentration＇ s change tendency in the windbox was very consistent with the change of temperature of the flue gas in the windboxes. More than 60% PCDD/Fs of the total PCDD/Fs emission amount was emitted at the end of the sintering bed. Only this part of the waste gas accounted for 12% of the total waste gas volume.展开更多
A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, w...A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, with a focus on the PBDF formation mechanism.The raw materials contributed greatly to input of PBDD/Fs into the cement kiln. The PBDD/F concentrations in the raw materials were much higher than those in particle samples from different process stages in the cement kiln. The PBDD/F concentrations in the clinkers were1.40% of the concentrations in the raw materials, which indicated that the high destruction efficiencies for PBDD/Fs by cement kiln. PBDD/F distribution patterns in particle samples collected from different process stages indicated the cement kiln backend was a major site for PBDD/F formation. PBDFs with high levels of halogenation, such as heptabrominated furans(Hp BDF), were the dominant contributors to the total PBDD/F concentrations and accounted for 42%–73% of the total PBDD/F concentrations in the particle samples. Our results showed that co-processing of municipal solid waste in a cement kiln may influence the congener profile of PBDD/Fs, especially for the higher halogenated PBDD fraction. In addition, there were significant correlations between the decabromodiphenyl ether and heptabrominated furan concentrations, which is an indicator of transformation from polybrominated diphenyl ethers to PBDD/Fs. Theoretical calculations were performed and demonstrated that elimination of HBr and Br_2 from polybrominated diphenyl ethers were the dominant formation pathways for PBDD/Fs. These pathways differed from that for polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs).展开更多
While routine monitoring poultry meat was obtained from breeding hens, dioxins contaminations were detected in Portugal. Levels of 430.9 pg PCDD/F-WHO-TEQ/g1 were found, which are higher than the official limits legal...While routine monitoring poultry meat was obtained from breeding hens, dioxins contaminations were detected in Portugal. Levels of 430.9 pg PCDD/F-WHO-TEQ/g1 were found, which are higher than the official limits legally allowed for this matrix (1.75 pg PCDD/F-WHO-TEQ/g). To identify the magnitude of the contaminations, 60 samples were collected from poultry farms and different matrices, namely: feed, water, wood shavings from the litters, muscle of the breeding hens, hatching eggs collected in the positive farm and muscle collected from broilers farms supplied by the positive breeding farm. The comparison of the dioxins congeners profiles showed that there was a coincidence of peaks of higher relative concentrations in the wood shavings, with the peaks of the highest relative concentration in the hatching eggs, especially the relative concentrations of the congeners 1,2,3,4,6,7,8-HpCDD and OCDD, which may be explained by the role of VLDLy in the delivery of triglycerides to the oocyte, where they will be used as the energy source for the developing embryo. The comparison of the dioxins congeners profiles of the breeding hens muscle with the poultry muscle, showed a coincidence of peaks of higher relative concentrations in the congeners 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDD and OCDD which may indicate a dechlorination pathway “in vivo”. Results allowed concluding that those wood shavings, improperly used as poultry litters, were certainly the source of contamination of the food chain.展开更多
Since the discovery of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)in the process of municipal solid waste incineration(MSWI),a large number of researches have been conducted to reveal their formation ...Since the discovery of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)in the process of municipal solid waste incineration(MSWI),a large number of researches have been conducted to reveal their formation mechanisms and emission characteristics.As one of national priority control pollutants,chlorinated organics are inclined to transfer into PCDD/Fs in the heterogeneously catalyzed process,which has been considered to be one of great challenges in environmental catalysis.However,so far direct evidences to support such a conversion process are insufficient,and the reaction mechanisms are lack of exploration.This study investigated the catalytic elimination of chlorobenzene(CBz)over a range of industrially applied active species including Pt,Ru,V,Ce and Mn oxides,and explored their reaction byproducts,chlorine adsorption/desorption behaviors and PCDD/F formations.We found that all of these species could generate the PCDD/Fs,amongst which,Mn species were the most active for PCDD/F formation.Approximately 140 ng I-TEQg-1 PCDD/Fs were detected on the Mn-CNT surface after ageing at250℃for 30 h.Even using the dichloromethane(DCM)as a precursor,significant PCDD/Fs were still detected.The Ru and V species were shown to generate much less polychlorinated byproducts and PCDD/Fs,owning to their sufficiently high abilities in Cl desorption,which were through the semi-Deacon and Br(?)nsted H reactions,respectively.展开更多
Production and pollution control situations of dioxins persistent organic pollutants in Guangxi were introduced.Pollution status of dioxins persistent organic pollutants in Guangxi was understood,and the existing prob...Production and pollution control situations of dioxins persistent organic pollutants in Guangxi were introduced.Pollution status of dioxins persistent organic pollutants in Guangxi was understood,and the existing problems in pollution control were analyzed,and finally pollution control countermeasures and suggestions were proposed.展开更多
During 2016, following the implementation of a dioxin contamination monitoring in poultry meat (ducks) in a slaughterhouse, a positive sample was found. The investigation identified the wood shavings used as bedding m...During 2016, following the implementation of a dioxin contamination monitoring in poultry meat (ducks) in a slaughterhouse, a positive sample was found. The investigation identified the wood shavings used as bedding material in the duck farm as the possible source of contamination of these animals. In this episode, contamination profiles of higher and lower concentrations, seem to be very similar, being OCDD, OCDF and 1,2,3,4,6,7,8-HpCDD responsible for 74.4% of the total contamination of those animals. The study revealed a reduction of poultry contamination after the removal of the source of contamination, with an average daily depletion percentage level ranging between 1.43% and 4.35%.展开更多
This study investigates the concentrations of 17 PCDD/Fs and 12 dl-PCBs congeners in soil samples collected from industrial areas in Cartagena de Indias(Colombia)and Valencia(Spain).The aim is to assess the characteri...This study investigates the concentrations of 17 PCDD/Fs and 12 dl-PCBs congeners in soil samples collected from industrial areas in Cartagena de Indias(Colombia)and Valencia(Spain).The aim is to assess the characteristic distribution patterns and the potential risk around cement plants within the selected locations,addressing the lack of data on PCDD/Fs and dl-PCBs in soils from the two studied areas.Soil samples were analysed using gas chromatography coupled to high-resolution mass spectrometry(GC-HRMS).The PCDD/Fs concentrations varied from 0.01 pg g^(-1) dw to 520.43 pg g^(-1) dw in Colombia and from 0.01 pg g^(-1) dw to 150.48 pg g^(-1) dw in Spain.For dl-PCBs,levels ranged from 0.03 pg g^(-1) dw to 1611.83 pg g^(-1) dw in Colombia and from 0.06 to 189.64 pg g^(-1) dw in Spain.Despite the differences observed in concentration terms between the two areas studied,the same pattern of congeners was observed.The hazard index(HI)values for exposure of adults and children in soil were,in overall,smaller than one(HI<1),while the total cancer risk(TCR)values exceeded the acceptable risk value of 106,which indicate probable non-carcinogenic and carcinogenic risks resulting from exposure to PCDD/Fs and dl-PCBs in these areas.The ecological risk was assessed using the Contamination Factor(CF)and the Ecological Risk Index(ERI),revealing significant contamination in the studied areas.展开更多
As a party of the Stockholm Convention on Per-sistent Organic Pollutants,China must submit its national implementation plan(NIP)for this convention.The strategy and action plan for reducing the release of dioxins in C...As a party of the Stockholm Convention on Per-sistent Organic Pollutants,China must submit its national implementation plan(NIP)for this convention.The strategy and action plan for reducing the release of dioxins in China are the most important components of the NIP.Three prob-lems are key points for developing such strategy and action plan-what are the key sources for applying the best avail-able technology/best environmental practice(BAT/BEP)to reduce the release of dioxins?How about the capacity for reducing the dioxins release from the key sources?Where are the areas of priority for applying BAT/BEP?This paper shows the efforts towards the solution of these problems.The list of key sources covering about half of the total dioxins release was determined considering four criteria.The capacity of key sources were estimated based on the difference between the emission factor corresponding to the actual situation in 2004 and that corresponding to the scenario that all key sources have been applied BAT/BEP to reduce the dioxins release.The priority analysis using the geographical information system(GIS)tool has revealed that eastern provinces should be of high priority in the future reduction activities of dioxins release in China.展开更多
Dioxin is a general designation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs）. They are two series of tricyclic, almost planar, aromatic compounds, which are composed of 75...Dioxin is a general designation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs）. They are two series of tricyclic, almost planar, aromatic compounds, which are composed of 75 PCDD and 135 PCDF congeners,respectively. Among them, the most toxic congener is 2, 3, 7, 8-TCDD, with the suggested permissible level for human 10×10<sup>-9</sup>mg/（kg·d）<sup>-1</sup>. The environmental scientists have expressed much concern over these compounds since the 1980s. Chlorine-containing展开更多
The aim of this research was to determine the residues of dioxins and dioxin-like polychlorinated biphenyls in cultured eel and find out the source of pollution and the distribution pattern of eels.One hundred samples...The aim of this research was to determine the residues of dioxins and dioxin-like polychlorinated biphenyls in cultured eel and find out the source of pollution and the distribution pattern of eels.One hundred samples of eel,4 fodder samples,and 12 environmental samples(water,plants,and soil)were collected from 4 cities and counties in Jiangxi Province,China.The contents of 17 kinds of dioxins(PCDD/Fs)and 12 kinds of dioxin-like polychlorinated biphenyls(dl-PCBs)were determined by high-resolution gas chromatography-tandem mass spectrometry,and the exposure risk was evaluated by using risk index.The total toxicity equivalence quantity(TEQ)of dioxin and dioxin-like polychlorinated biphenyls in eel and fodder samples collected in the study area were 0.65±0.31 pg/g and 0.10±0.02 pg/g,respectively.Dl-PCBs were the main dioxin pollution in eel and fodder samples.2,3’,4,4’,5-pentachlorodiphenyl and 2,3,3’,4,4’-pentachlorobiphenyl were the main contributing monomers.The environmental samples were mainly polluted by polychlorinated dibenzo-p-dioxins(PCDDs),with the main contributing monomer being Octachlorodibenzodioxins(OCDD),while 3,3’,4,4’,5-pentachlorobiphenyl and 2,3,4,7,8-pentachlorodibenzofuran were the main toxic compounds in eel and fodder.The dioxin pollution of eels cultured in Jiangxi Province was mainly from fodder polluted via dl-PCBs.The meat segment VI(tail)exhibited a strong enrichment effect of polychlorinated benzofurans(PCDFs).It should be the key part for dioxins and dioxin-like polychlorinated biphenyls assessment.Further,the results were helpful to improve the edible safety of eel products and the efficiency of the risk assessment of dioxins and dioxin-like polychlorinated biphenyls in fish.展开更多
The mechanism of the multiple-pathway and multiple-step degradation reactions of 2,3,7,8-tetrachlorinated dibenzo-p-dioxins with H and Cl atoms is investigated using the density functional theory.The electronic struct...The mechanism of the multiple-pathway and multiple-step degradation reactions of 2,3,7,8-tetrachlorinated dibenzo-p-dioxins with H and Cl atoms is investigated using the density functional theory.The electronic structures and the minimum energy path(MEP)are calculated at the B3LYP/6-311+G(d,p)level,and energetic information(single-point)is further refined at the B3LYP/6-311++G(3df,2p)level.The main possible ring opening reaction pathways of the C–O bond breakdown include indirect cleavage ring opening reaction,hydrogen addition reaction,hydrogen addition elimination reaction,and chlorine addition elimination reaction.Ten reaction steps of the six reaction pathways are considered.Our calculations indicate that hydrogen addition reaction step TS1c is of the smallest barrier height,and indirect cleavage ring opening reaction channel has the largest barrier height and is the most endothermic.展开更多
The management of electronic waste(e-waste),which can be a source of both useful materials and toxic substances,depending on the processing method,is important for promoting material cycling.In this study,we used the ...The management of electronic waste(e-waste),which can be a source of both useful materials and toxic substances,depending on the processing method,is important for promoting material cycling.In this study,we used the dioxin-responsive chemical-activated luciferase gene expression(DR-CALUX)assay combined with gas chromatographyehigh-resolution mass spectrometry to evaluate the levels of dioxin-like compounds in surface soils and river sediments collected in and around an e-waste-processing village in northern Vietnam.The WHO-TEQs(Toxic equivalents)of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs),coplanar polychlorinated biphenyls(Co-PCBs),and polybrominated dibenzo-pdioxins and dibenzofurans(PBDD/Fs)in soils collected in January 2012 ranged from 0.29 to 310 pg/g(median 2.9 pg/g,n=32),and the WHO-TEQs in sediments ranged from 0.96 to 58 pg/g(median 4.4 pg/g,n=8).Dioxin-like activities(CALUX-TEQs[2,3,7,8-TCDD equivalent])in soils collected in January 2012,2013,and 2014 ranged from<30 to 4300 pg/g(median<30 pg/g,n=96),and the activities in sediments ranged from<30 to 4000 pg/g(median 33 pg/g,n=24).Dioxin-like compounds accumulated in samples collected around e-waste-processing areas such as open-burning sites and e-waste-processing workshops,and the compounds may be transported from their sources to surrounding areas over the course of several years.Some of the CALUX-TEQs,but not WHO-TEQs,values were higher than the maximum acceptable WHO-TEQs promulgated by various authorities,indicating that all dioxin-like compounds should be evaluated in samples collected from e-waste-processing areas.Our findings suggest that open burning and open storage of e-waste should be prohibited and that wastewater treatment should be implemented at each workshop to reduce contamination by dioxin-like compounds from e-waste.展开更多
This comprehensive review synthesizes findings from the studies conducted for more than two decades to assess en-vironmental and human health impacts near Spain's first hazardous waste incinerator(HWI)located in C...This comprehensive review synthesizes findings from the studies conducted for more than two decades to assess en-vironmental and human health impacts near Spain's first hazardous waste incinerator(HWI)located in Constantí(Tarra-gona,Catalonia).Through integrated analysis of polychlorinated dibenzo-p-dioxins/furans(PCDD/Fs)and metals across soil,vegetation,human tissues,and dietary matrices,the studies have shown:(1)PCDD/F concentrations decreased 75-96%in biological samples and dietary intake over 20 years,aligning with global emission reductions rather than HWI-4 operations;(2)metal trajectories showed arsenic intermittently exceeding carcinogenic thresholds in soils(1.1×10^(-4) risk index)and chromium accumulating in autopsy tissues(+16% in kidney),although without HWI-specific spatial gradi-ents;(3)systemic biomarkers revealed policy-driven declines—blood lead dropped 70% post-EU regulations,while mer-cury became undetectable in tissues post-2010.Health risk assessments confirmed that PCDD/F intake(0.122 pg WHO-TEQ/kg/day)remained still below WHO thresholds,with no attributable cancer risks for metals except legacy arsenic.The studies included in the program of surveillance show that PCDD/Fs and metals emissions by the HWI have meant a rather low contribution to population exposure to metals and PCDD/Fs compared to dietary and historical sources.How-ever,residual risks warrant attention.It mainly concerns chromium speciation and arsenic in soils,as well as the effects on vulnerable subpopulations and the synergistic effects among toxicants.Epidemiological studies are also required.展开更多
基金financially supported by the Science and Technology Innovation Program of Hunan Province(2024AQ2008)。
文摘The fly ash from waste incineration poses a serious threat to human health due to its high content of dioxins.Hydrothermal treatment is an efficient and clean method on the decomposition and detoxifying of fly ash.To study the degradation mechanism of dioxins,this paper uses molecular dynamics(MD)to simulate the hydrothermal reaction process of polychlorinated dibenzo-p-dioxins(PCDDs)under different conditions,and the degradation mechanism of PCDDs is obtained.The results show that the degradation of PCDDs includes two pathways:the first pathway is the substitution of Cl groups by hydroxyl groups to form low-chlorine substitution products through direct hydrogenation,and the second pathway is the formation of non-toxic benzene ring structures accompanied by the cleavage of C—O bonds.The two degradation pathways of PCDDs well explain the changes in toxicity before and after the hydrothermal treatment of fly ash,which is consistent with experimental results.This study provides theoretical guidance for the harmless treatment process of fly ash via hydrothermal method.
文摘Dioxins, which are of the most toxic materials on the earth, are principal emitted from waste incineration process. The molecular structures, toxicity parameters, such as toxicity equivalency factor, tolerable daily intake and physic-chemical properties of dioxins are briefly summarized. Three formation mechanisms of dioxins in waste incineration process, namely as de novo synthesis, mechanisms involving small organic molecular as precursors and homogenous gas phase reaction mechanism are alto reviewed. The influencing factors for dioxins formation during waste incineration process are also discussed. Three major methods for reducing dioxins emission from waste incineration process are discussed based upon the formation mechanisms and influencing factors. A new waste incineration process with low dioxins emission and low hydrogen chloride corrosion has been proposed based on multi- stage unit operation principal according to formation mechanisms of dioxins and potential production location in waste incinerators.
基金supported by the National Natural Science Foundation of China(No. 20921063)the Ministry of Science and Technology of China(No. 2008FY210100,2007AA061602,2007BAC27B01)
文摘The ambient air in vicinity of different industrial sources for PCDD/PCDFs was sampled by TSP/PM10 active samplers and passive PUF disk samplers in Tangshan City, a metropolis containing clusters of various industrial plants. The TEQ concentrations of PCDD/PCDFs ranged from 44.2 to 394.1 fg I-TEQ/m^3 with an average of 169.9 fg I-TEQ]m^3. 2,3,4,7,8-PeCDF was the dominant contributor to ∑TEQ, contributing 41% （12% to 55%）, while 1,2,3,4,6,7,8-HpCDE OCDD and OCDF were the major congeners for the total concentrations. The ratios of ∑PCDF/∑PCDD reached 2.54 on average, suggesting that de novo synthesis in thermal processes played an important role to the airborne pollution of PCDD/PCDFs. The similarities congener profiles indicated that TSP and PM10 active sampling methods are comparable for the determination of the PCDD/PCDFs in ambient air, and the ratios of concentrations determined by the two methods suggested that the PCDD/PCDFs tended to stay in fine particles. It was found that 2,3,7,8-TCDF and OCDD were the dominating congeners in the passive PUF disks samples. Through principal components analysis, the coke industry was suggested to be a relatively high potential emission source for PCDD/PCDFs in the ambient air of Tangshan, which was possibly formed by de novo synthesis mechanism. In this study, the atmospheric impacts to the environment from different industrial sources could be ranked as follows （from high to low）： coking, iron sintering, steel making, power generation and chlorinate alkali chemical production industries.
文摘Bulk（wet and dry） deposition samples were collected in Saitama Prefecture, Japan throughout a year（February 8, 2012 to February 7, 2013） to estimate the influence of dioxins emitting from waste incinerators on river water quality. The annual deposition flux of dioxins was 3.3 ng-toxic equivalent（TEQ）/m^2/year. Source identification using indicative congeners estimated that 82% of dioxin TEQ in the bulk deposition（2.7 ng-TEQ/m^2/year）was combustion-originated, indicating that most of the dioxins in the deposition were derived from waste incinerators. In Saitama prefecture the annual flux of combustionoriginated dioxins in depositions was apparently consistent with that of dioxin emission into the air from waste incinerators. The TEQ of combustion-originated dioxins in the deposition per rainfall was 2.4 pg-TEQ/L on annual average, exceeding the environmental quality standard（EQS） for water in Japan of 1 pg-TEQ/L. This suggests there is a possibility that dioxins in atmospheric deposition have a significant influence on the water quality of urban rivers which rainwater directly flows into because of many paved areas in the basins.The influence of combustion-originated dioxin in the deposition on the water quality of Ayase River, an urban river heavily polluted with dioxins, was estimated at 0.29 pg-TEQ/L on annual average in 2015. It seems that dioxins in atmospheric deposition from waste incinerators have a significant influence on water quality of some urban rivers via rainwater though the dioxins in the ambient air have achieved the EQS for atmosphere at all monitoring sites in Japan.
基金the National Natural Science Foundation of China (50104003)
文摘Loaded on the cordierite, the rare earth doped composite catalyst was prepared by sol-gel method combined with dipping technique. Taking Orthodichlorobenzene as model, the catalyst was used to remove the dioxins of the waste gas. The results showed that at 280 ℃ and gas space velocity being 8000 h-1, the orthodichlorobenzene could be removed effectivily by the prepared CeO-TiO2-V2O5 composite catalyst whose activity was remarkably enhanced by the doping of Ce, while the industrial side-stream test of dioxins from refuse incineration smoke indicated that the decomposition rate could reach above 93% under the same conditions.
文摘Humans and animals can be exposed to Dioxins and Furans through ingestion of fatty food, skin contact, and breathing contaminated air. Resulting health problems include skin disease, immune problems, and cancers. Managing the release of these chemicals is therefore important. The Stockholm Convention on Persistent Organic Pollutants requires parties to adopt measures that reduce sources of these chemicals. Sierra Leone developed its National Implementation Plan (NIP) in 2008, in compliance with this requirement. However, no known further steps have been taken, particularly at community level. In 2013, the UNDP’s GEF/SGP funded a pilot project to manage the release of Dioxins and Furans from two dumpsites in Freetown, Sierra Leone. This work was sponsored with funds from that project. The work sought to delineate the exposure of communities within and around the Bormeh-Kingtom dumpsite (Kingtom, Kolleh town, Ascension town, Crab town, and Congo town) to the chemicals. The study considered sources of exposure, relative quantities generated per year, and the routes of exposure. This exposure study is a first step in managing the release from those sources. Enumerators deployed at the dumpsite every day, 7:00 AM to 6:00 PM, for three months, quantifying and recording source materials. The amount of source materials dumped per day informed calculation of Dioxin/Furan releases in grams toxicity equivalence per year. The results revealed a release of 128.914 g TEQ/year in air and residue. This implies that the communities are at high risk of inhalation and dermal exposure. Livestock, mainly pigs, are also exposed as they feed on the waste deposited in the dumpsite. Humans in turn feed on the livestock, a recipe for biomagnification. The project team has been working on developing Best Management Practices to suppress the release of the chemicals.
基金supported by the National Natural Science Foundation of China(21037003,20921063)the National 973 Program(2009CB421606)
文摘The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed. The influence of temperature change on the PCDD/Fs emission from the sintering process and the formation mechanism of PCDD/Fs were discussed. The result has shown that among the seventeen gaseous and particle-bound PCDD/Fs in the flue gas of different windboxes, furans occupied the major place. The proportion of the gaseous PCDD/Fs in most windboxes is from 40% to 60%. The change tendencies of the concentration of both the gaseous and particle-bound PCDD/Fs were similar, with a higher level at the end of the sintering bed. The PCDD/Fs concentration＇ s change tendency in the windbox was very consistent with the change of temperature of the flue gas in the windboxes. More than 60% PCDD/Fs of the total PCDD/Fs emission amount was emitted at the end of the sintering bed. Only this part of the waste gas accounted for 12% of the total waste gas volume.
基金supported by the National Natural Science Foundation of China(No.21777172)the Collaborative Project supported by Chinese Academy of Sciences and Hebei Academy of Sciences(No.181602)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2016038)
文摘A field study and theoretical calculations were performed to clarify the levels, profiles, and distributions of polybrominated dibenzo-p-dioxins and dibenzofurans(PBDD/Fs) in a cement kiln co-processing solid waste, with a focus on the PBDF formation mechanism.The raw materials contributed greatly to input of PBDD/Fs into the cement kiln. The PBDD/F concentrations in the raw materials were much higher than those in particle samples from different process stages in the cement kiln. The PBDD/F concentrations in the clinkers were1.40% of the concentrations in the raw materials, which indicated that the high destruction efficiencies for PBDD/Fs by cement kiln. PBDD/F distribution patterns in particle samples collected from different process stages indicated the cement kiln backend was a major site for PBDD/F formation. PBDFs with high levels of halogenation, such as heptabrominated furans(Hp BDF), were the dominant contributors to the total PBDD/F concentrations and accounted for 42%–73% of the total PBDD/F concentrations in the particle samples. Our results showed that co-processing of municipal solid waste in a cement kiln may influence the congener profile of PBDD/Fs, especially for the higher halogenated PBDD fraction. In addition, there were significant correlations between the decabromodiphenyl ether and heptabrominated furan concentrations, which is an indicator of transformation from polybrominated diphenyl ethers to PBDD/Fs. Theoretical calculations were performed and demonstrated that elimination of HBr and Br_2 from polybrominated diphenyl ethers were the dominant formation pathways for PBDD/Fs. These pathways differed from that for polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs).
文摘While routine monitoring poultry meat was obtained from breeding hens, dioxins contaminations were detected in Portugal. Levels of 430.9 pg PCDD/F-WHO-TEQ/g1 were found, which are higher than the official limits legally allowed for this matrix (1.75 pg PCDD/F-WHO-TEQ/g). To identify the magnitude of the contaminations, 60 samples were collected from poultry farms and different matrices, namely: feed, water, wood shavings from the litters, muscle of the breeding hens, hatching eggs collected in the positive farm and muscle collected from broilers farms supplied by the positive breeding farm. The comparison of the dioxins congeners profiles showed that there was a coincidence of peaks of higher relative concentrations in the wood shavings, with the peaks of the highest relative concentration in the hatching eggs, especially the relative concentrations of the congeners 1,2,3,4,6,7,8-HpCDD and OCDD, which may be explained by the role of VLDLy in the delivery of triglycerides to the oocyte, where they will be used as the energy source for the developing embryo. The comparison of the dioxins congeners profiles of the breeding hens muscle with the poultry muscle, showed a coincidence of peaks of higher relative concentrations in the congeners 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDD and OCDD which may indicate a dechlorination pathway “in vivo”. Results allowed concluding that those wood shavings, improperly used as poultry litters, were certainly the source of contamination of the food chain.
基金financially supported by the National Natural Science Foundation of China(Nos.21777140,21922607)the Outstanding Youth Project of Zhejiang Natural Science Foundation(No.LR19E080004)。
文摘Since the discovery of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs)in the process of municipal solid waste incineration(MSWI),a large number of researches have been conducted to reveal their formation mechanisms and emission characteristics.As one of national priority control pollutants,chlorinated organics are inclined to transfer into PCDD/Fs in the heterogeneously catalyzed process,which has been considered to be one of great challenges in environmental catalysis.However,so far direct evidences to support such a conversion process are insufficient,and the reaction mechanisms are lack of exploration.This study investigated the catalytic elimination of chlorobenzene(CBz)over a range of industrially applied active species including Pt,Ru,V,Ce and Mn oxides,and explored their reaction byproducts,chlorine adsorption/desorption behaviors and PCDD/F formations.We found that all of these species could generate the PCDD/Fs,amongst which,Mn species were the most active for PCDD/F formation.Approximately 140 ng I-TEQg-1 PCDD/Fs were detected on the Mn-CNT surface after ageing at250℃for 30 h.Even using the dichloromethane(DCM)as a precursor,significant PCDD/Fs were still detected.The Ru and V species were shown to generate much less polychlorinated byproducts and PCDD/Fs,owning to their sufficiently high abilities in Cl desorption,which were through the semi-Deacon and Br(?)nsted H reactions,respectively.
文摘Production and pollution control situations of dioxins persistent organic pollutants in Guangxi were introduced.Pollution status of dioxins persistent organic pollutants in Guangxi was understood,and the existing problems in pollution control were analyzed,and finally pollution control countermeasures and suggestions were proposed.
文摘During 2016, following the implementation of a dioxin contamination monitoring in poultry meat (ducks) in a slaughterhouse, a positive sample was found. The investigation identified the wood shavings used as bedding material in the duck farm as the possible source of contamination of these animals. In this episode, contamination profiles of higher and lower concentrations, seem to be very similar, being OCDD, OCDF and 1,2,3,4,6,7,8-HpCDD responsible for 74.4% of the total contamination of those animals. The study revealed a reduction of poultry contamination after the removal of the source of contamination, with an average daily depletion percentage level ranging between 1.43% and 4.35%.
基金funded by the European Commission through the European Regional Development Funds(ERDF)Operational Programme of the Valencia Region(2014-2020).
文摘This study investigates the concentrations of 17 PCDD/Fs and 12 dl-PCBs congeners in soil samples collected from industrial areas in Cartagena de Indias(Colombia)and Valencia(Spain).The aim is to assess the characteristic distribution patterns and the potential risk around cement plants within the selected locations,addressing the lack of data on PCDD/Fs and dl-PCBs in soils from the two studied areas.Soil samples were analysed using gas chromatography coupled to high-resolution mass spectrometry(GC-HRMS).The PCDD/Fs concentrations varied from 0.01 pg g^(-1) dw to 520.43 pg g^(-1) dw in Colombia and from 0.01 pg g^(-1) dw to 150.48 pg g^(-1) dw in Spain.For dl-PCBs,levels ranged from 0.03 pg g^(-1) dw to 1611.83 pg g^(-1) dw in Colombia and from 0.06 to 189.64 pg g^(-1) dw in Spain.Despite the differences observed in concentration terms between the two areas studied,the same pattern of congeners was observed.The hazard index(HI)values for exposure of adults and children in soil were,in overall,smaller than one(HI<1),while the total cancer risk(TCR)values exceeded the acceptable risk value of 106,which indicate probable non-carcinogenic and carcinogenic risks resulting from exposure to PCDD/Fs and dl-PCBs in these areas.The ecological risk was assessed using the Contamination Factor(CF)and the Ecological Risk Index(ERI),revealing significant contamination in the studied areas.
基金This research was supported by funding provided by the Stockholm Convention Implementing Office at State Environmental Protection Administration(CIO/SEPA).
文摘As a party of the Stockholm Convention on Per-sistent Organic Pollutants,China must submit its national implementation plan(NIP)for this convention.The strategy and action plan for reducing the release of dioxins in China are the most important components of the NIP.Three prob-lems are key points for developing such strategy and action plan-what are the key sources for applying the best avail-able technology/best environmental practice(BAT/BEP)to reduce the release of dioxins?How about the capacity for reducing the dioxins release from the key sources?Where are the areas of priority for applying BAT/BEP?This paper shows the efforts towards the solution of these problems.The list of key sources covering about half of the total dioxins release was determined considering four criteria.The capacity of key sources were estimated based on the difference between the emission factor corresponding to the actual situation in 2004 and that corresponding to the scenario that all key sources have been applied BAT/BEP to reduce the dioxins release.The priority analysis using the geographical information system(GIS)tool has revealed that eastern provinces should be of high priority in the future reduction activities of dioxins release in China.
基金Project supported by the National Natural Science Foundation of China.
文摘Dioxin is a general designation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs）. They are two series of tricyclic, almost planar, aromatic compounds, which are composed of 75 PCDD and 135 PCDF congeners,respectively. Among them, the most toxic congener is 2, 3, 7, 8-TCDD, with the suggested permissible level for human 10×10<sup>-9</sup>mg/（kg·d）<sup>-1</sup>. The environmental scientists have expressed much concern over these compounds since the 1980s. Chlorine-containing
基金supported by the Ministry of Agriculture and Rural Affairs Agricultural Product Quality and Safety Supervision(Risk Assessment)Special Project:NZF[2019]No.10the Natural Science Foundation of Liaoning Province(2021-BS-228).
文摘The aim of this research was to determine the residues of dioxins and dioxin-like polychlorinated biphenyls in cultured eel and find out the source of pollution and the distribution pattern of eels.One hundred samples of eel,4 fodder samples,and 12 environmental samples(water,plants,and soil)were collected from 4 cities and counties in Jiangxi Province,China.The contents of 17 kinds of dioxins(PCDD/Fs)and 12 kinds of dioxin-like polychlorinated biphenyls(dl-PCBs)were determined by high-resolution gas chromatography-tandem mass spectrometry,and the exposure risk was evaluated by using risk index.The total toxicity equivalence quantity(TEQ)of dioxin and dioxin-like polychlorinated biphenyls in eel and fodder samples collected in the study area were 0.65±0.31 pg/g and 0.10±0.02 pg/g,respectively.Dl-PCBs were the main dioxin pollution in eel and fodder samples.2,3’,4,4’,5-pentachlorodiphenyl and 2,3,3’,4,4’-pentachlorobiphenyl were the main contributing monomers.The environmental samples were mainly polluted by polychlorinated dibenzo-p-dioxins(PCDDs),with the main contributing monomer being Octachlorodibenzodioxins(OCDD),while 3,3’,4,4’,5-pentachlorobiphenyl and 2,3,4,7,8-pentachlorodibenzofuran were the main toxic compounds in eel and fodder.The dioxin pollution of eels cultured in Jiangxi Province was mainly from fodder polluted via dl-PCBs.The meat segment VI(tail)exhibited a strong enrichment effect of polychlorinated benzofurans(PCDFs).It should be the key part for dioxins and dioxin-like polychlorinated biphenyls assessment.Further,the results were helpful to improve the edible safety of eel products and the efficiency of the risk assessment of dioxins and dioxin-like polychlorinated biphenyls in fish.
基金supported by the Innovative Research Team of Green Chemical Technology in University of Heilongjiang Province.supported by the National Basic Research Program of China("973"Project)(Grant No.2012CB723308)+2 种基金the National Natural Science Foundation of China(Grant Nos.51337002 and 50977019)the Doctoral Foundation by the Ministry of Education of China(Grant No.20112303110005)the Science Foundation for Distinguished Young Scholar of Heilongjiang Province(Grant No.JC201206)
文摘The mechanism of the multiple-pathway and multiple-step degradation reactions of 2,3,7,8-tetrachlorinated dibenzo-p-dioxins with H and Cl atoms is investigated using the density functional theory.The electronic structures and the minimum energy path(MEP)are calculated at the B3LYP/6-311+G(d,p)level,and energetic information(single-point)is further refined at the B3LYP/6-311++G(3df,2p)level.The main possible ring opening reaction pathways of the C–O bond breakdown include indirect cleavage ring opening reaction,hydrogen addition reaction,hydrogen addition elimination reaction,and chlorine addition elimination reaction.Ten reaction steps of the six reaction pathways are considered.Our calculations indicate that hydrogen addition reaction step TS1c is of the smallest barrier height,and indirect cleavage ring opening reaction channel has the largest barrier height and is the most endothermic.
基金supported by the Society for the Promotion of Science and Environment Research and Technology Development Fund(no.3K133010 and no.3K153001)of the Ministry of the Environment,Japansupported by the Ministry of Education,Culture,Sports,Science and Technology,Japan(MEXT)to a project on Center of Excellence for Cooperative and Collaborative Studies e Leading Academia in Marine and Environmental Research(LaMer).
文摘The management of electronic waste(e-waste),which can be a source of both useful materials and toxic substances,depending on the processing method,is important for promoting material cycling.In this study,we used the dioxin-responsive chemical-activated luciferase gene expression(DR-CALUX)assay combined with gas chromatographyehigh-resolution mass spectrometry to evaluate the levels of dioxin-like compounds in surface soils and river sediments collected in and around an e-waste-processing village in northern Vietnam.The WHO-TEQs(Toxic equivalents)of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs),coplanar polychlorinated biphenyls(Co-PCBs),and polybrominated dibenzo-pdioxins and dibenzofurans(PBDD/Fs)in soils collected in January 2012 ranged from 0.29 to 310 pg/g(median 2.9 pg/g,n=32),and the WHO-TEQs in sediments ranged from 0.96 to 58 pg/g(median 4.4 pg/g,n=8).Dioxin-like activities(CALUX-TEQs[2,3,7,8-TCDD equivalent])in soils collected in January 2012,2013,and 2014 ranged from<30 to 4300 pg/g(median<30 pg/g,n=96),and the activities in sediments ranged from<30 to 4000 pg/g(median 33 pg/g,n=24).Dioxin-like compounds accumulated in samples collected around e-waste-processing areas such as open-burning sites and e-waste-processing workshops,and the compounds may be transported from their sources to surrounding areas over the course of several years.Some of the CALUX-TEQs,but not WHO-TEQs,values were higher than the maximum acceptable WHO-TEQs promulgated by various authorities,indicating that all dioxin-like compounds should be evaluated in samples collected from e-waste-processing areas.Our findings suggest that open burning and open storage of e-waste should be prohibited and that wastewater treatment should be implemented at each workshop to reduce contamination by dioxin-like compounds from e-waste.
文摘This comprehensive review synthesizes findings from the studies conducted for more than two decades to assess en-vironmental and human health impacts near Spain's first hazardous waste incinerator(HWI)located in Constantí(Tarra-gona,Catalonia).Through integrated analysis of polychlorinated dibenzo-p-dioxins/furans(PCDD/Fs)and metals across soil,vegetation,human tissues,and dietary matrices,the studies have shown:(1)PCDD/F concentrations decreased 75-96%in biological samples and dietary intake over 20 years,aligning with global emission reductions rather than HWI-4 operations;(2)metal trajectories showed arsenic intermittently exceeding carcinogenic thresholds in soils(1.1×10^(-4) risk index)and chromium accumulating in autopsy tissues(+16% in kidney),although without HWI-specific spatial gradi-ents;(3)systemic biomarkers revealed policy-driven declines—blood lead dropped 70% post-EU regulations,while mer-cury became undetectable in tissues post-2010.Health risk assessments confirmed that PCDD/F intake(0.122 pg WHO-TEQ/kg/day)remained still below WHO thresholds,with no attributable cancer risks for metals except legacy arsenic.The studies included in the program of surveillance show that PCDD/Fs and metals emissions by the HWI have meant a rather low contribution to population exposure to metals and PCDD/Fs compared to dietary and historical sources.How-ever,residual risks warrant attention.It mainly concerns chromium speciation and arsenic in soils,as well as the effects on vulnerable subpopulations and the synergistic effects among toxicants.Epidemiological studies are also required.
