The effect of sulfur dioxide （SO2） on the formation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） has been studied in an entrained-flow reactor （EFR） under simulated wa...The effect of sulfur dioxide （SO2） on the formation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） has been studied in an entrained-flow reactor （EFR） under simulated waste combustion conditions. A chlorination model based on conditional probability was employed to evaluate the homologue patterns of PCDDs and PCDFs. Results revealed that the presence of SO2 did not alter the formation pathway although SO2 suppressed PCDD/F formation. The prediction model of PCDF showed good agreement with the experimental data （R--0.95）, whereas the prediction for PCDDs did not correlate well with the experimental data. This may be explained because potential chlorination pathways play a significant role in PCDF formation, whereas PCDDs are mainly formed through condensation reactions. Furthermore, the result indicated that the steric hindrance during formation has more effects on PCDD than on PCDF due to the symmetric molecular structures of PCDDs.展开更多
During the start-up and unstable combustion periods,even the state-of-the-art incinerators emit polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/PCDF) in stack gases at concentrations that are up to 1000 times...During the start-up and unstable combustion periods,even the state-of-the-art incinerators emit polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/PCDF) in stack gases at concentrations that are up to 1000 times higher than normal operation. Therefore,incinerators and other sources with variation of PCDD/PCDF release into air cannot be reliably monitored by the conventional short-term sampling that covers only 0.1%to 0.2%of the yearly operating time.A more comprehensive monitoring regime is required.This paper describes different applications of continuous PCDD/PCDF sampling in some European countries.The cases demonstrate that flexible regimes for continuous sampling can be crafted and applied by governments or regional/local authorities.Such regimes range from a countrywide,continuous requirement for selected facility types(e.g.,waste incinerators) to a facility-specific regime that applies,for example,to new facilities for a defined time period until the facility has demonstrated continuous compliance with regulatory limits. Countries implementing the Stockholm Convention are suggested to evaluate in their Best available technology/Best environmental practice(BAT/BEP) activities the usefulness of long-term sampling by,for example,designating institutes related to the environmental ministry or regional authorities to supervise long-term sampling regimes at relevant facilities in their country/areas,beginning with priority sources(e.g.,facilities used for destruction of persistent organic pollutants(POPs) or hazardous waste processing) . This paper presents and discusses the results of the AMESA long-term monitoring system having demonstrated that in addition to PCDD/PCDF all other unintentionally produced POPs listed in the Stockholm Convention could be supervised.展开更多
Many environment problems of the full using of several categories of processing include mining,heat generators,direct combustion of forest fires,cement production,power plant,transport,medical waste.Dioxin/furan relea...Many environment problems of the full using of several categories of processing include mining,heat generators,direct combustion of forest fires,cement production,power plant,transport,medical waste.Dioxin/furan releases from these categories are one of these environment problems.Possible lines of reducing the PCDD/PCDF (Polychlorinated dibenzo-para-dioxins/Polychlorinated dibenzofurans) releases from these categories are elucidated.The contribution of this paper is present the identification and estimation of the latest figure of dioxin/furan releases in the climate of environment of Jordan in the period 2000-2008 from the following categories (cement,aluminum,ceramic,medical waste,power plant,land fill,ferrous and non-ferrous metals,uncontrolled combustion process (biomass burning,waste burning,accidental fires in house,transport).These finding shows the sign of growth of estimated PCDD/PCDF releases from categories which did not calculated and followed after 2003.The result shows the highest PCDD/PCDF release from landfill fires (62.75 g TEQ/year),medical waste (8.8264 g TEQ/year),and transport (3.0145 g TEQ/year).Jordan seeks by next years,a reduction in total releases of dioxins and furans from sources resulting from human activity.This challenge will apply to the aggregate of releases to the air nationwide and of releases to the water within the Jordan area.Jordan should conduct air monitoring for dioxin in order to track fluctuations in atmospheric deposition levels.展开更多
The identification of contamination sources within the food chain with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs), (“dioxins”), and PCBs is difficult and complex. PCDD/PCDF ...The identification of contamination sources within the food chain with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs), (“dioxins”), and PCBs is difficult and complex. PCDD/PCDF can be formed as unintentional compounds in a number of chemical processes as well as in almost every combustion process. PCBs were intentionally produced chemicals that were manufactured for decades before the ban in marketing and use in many countries around 1985. The pattern of occurrence can change from the original source in particular via feedingstuffs to food of animal origin as result of bioaccumulation. A number of examples illustrate the challenging detective work and key scientific aspects for identification of the sources, for support of the risk management and for performance of monitoring programs. The contamination of milk and milk products in European countries with dioxins was caused by compound feeds containing citrus pulp pellets from Brazil which had high dioxin levels as a result of the use of heavily contaminated lime used for neutralization. The Belgian dioxin crisis was caused by a feed additive heavily contaminated with PCBs which were discharged into a recycled fat used in the production of animal feed. Guar gum from India was contaminated with sodium pentachlorophenate and dioxins. Clay was found to be possibly highly contaminated with dioxins possibly formed by geothermal processes over time;use of such clay as feed additive or for human intake led to elevated dioxin levels in food and humans. Bioanalytical screening in combination with comprehensive physicochemical investigations led to the detection of brominated flame retardants and brominated dioxins in a feed additive. Buffalo milk was contaminated in Italy presumably caused by illegal deposition of waste. High PCB levels in fuel oil for drying of breadcrumb used as a feed ingredient caused a major dioxin crisis with pork meat in Ireland. Fatty acids for technical purposes originating from a biodiesel company were used for production of feed fat which contaminated parts of the food chain in Germany. In addition to effects on human and animal health these incidents also have serious economic consequences which could be mitigated by more frequent control on food and feed. Addressing both these issues, the European Community has developed a strategy to reduce the presence of dioxins and PCBs in the environment and in feed and food comprising the establishment of maximum and action levels.展开更多
基金Project supported by the China Scholarship Council Foundation (2003) the National Natural Science Foundation of China (No. 50576082).
文摘The effect of sulfur dioxide （SO2） on the formation of polychlorinated dibenzo-p-dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） has been studied in an entrained-flow reactor （EFR） under simulated waste combustion conditions. A chlorination model based on conditional probability was employed to evaluate the homologue patterns of PCDDs and PCDFs. Results revealed that the presence of SO2 did not alter the formation pathway although SO2 suppressed PCDD/F formation. The prediction model of PCDF showed good agreement with the experimental data （R--0.95）, whereas the prediction for PCDDs did not correlate well with the experimental data. This may be explained because potential chlorination pathways play a significant role in PCDF formation, whereas PCDDs are mainly formed through condensation reactions. Furthermore, the result indicated that the steric hindrance during formation has more effects on PCDD than on PCDF due to the symmetric molecular structures of PCDDs.
文摘During the start-up and unstable combustion periods,even the state-of-the-art incinerators emit polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/PCDF) in stack gases at concentrations that are up to 1000 times higher than normal operation. Therefore,incinerators and other sources with variation of PCDD/PCDF release into air cannot be reliably monitored by the conventional short-term sampling that covers only 0.1%to 0.2%of the yearly operating time.A more comprehensive monitoring regime is required.This paper describes different applications of continuous PCDD/PCDF sampling in some European countries.The cases demonstrate that flexible regimes for continuous sampling can be crafted and applied by governments or regional/local authorities.Such regimes range from a countrywide,continuous requirement for selected facility types(e.g.,waste incinerators) to a facility-specific regime that applies,for example,to new facilities for a defined time period until the facility has demonstrated continuous compliance with regulatory limits. Countries implementing the Stockholm Convention are suggested to evaluate in their Best available technology/Best environmental practice(BAT/BEP) activities the usefulness of long-term sampling by,for example,designating institutes related to the environmental ministry or regional authorities to supervise long-term sampling regimes at relevant facilities in their country/areas,beginning with priority sources(e.g.,facilities used for destruction of persistent organic pollutants(POPs) or hazardous waste processing) . This paper presents and discusses the results of the AMESA long-term monitoring system having demonstrated that in addition to PCDD/PCDF all other unintentionally produced POPs listed in the Stockholm Convention could be supervised.
文摘Many environment problems of the full using of several categories of processing include mining,heat generators,direct combustion of forest fires,cement production,power plant,transport,medical waste.Dioxin/furan releases from these categories are one of these environment problems.Possible lines of reducing the PCDD/PCDF (Polychlorinated dibenzo-para-dioxins/Polychlorinated dibenzofurans) releases from these categories are elucidated.The contribution of this paper is present the identification and estimation of the latest figure of dioxin/furan releases in the climate of environment of Jordan in the period 2000-2008 from the following categories (cement,aluminum,ceramic,medical waste,power plant,land fill,ferrous and non-ferrous metals,uncontrolled combustion process (biomass burning,waste burning,accidental fires in house,transport).These finding shows the sign of growth of estimated PCDD/PCDF releases from categories which did not calculated and followed after 2003.The result shows the highest PCDD/PCDF release from landfill fires (62.75 g TEQ/year),medical waste (8.8264 g TEQ/year),and transport (3.0145 g TEQ/year).Jordan seeks by next years,a reduction in total releases of dioxins and furans from sources resulting from human activity.This challenge will apply to the aggregate of releases to the air nationwide and of releases to the water within the Jordan area.Jordan should conduct air monitoring for dioxin in order to track fluctuations in atmospheric deposition levels.
文摘The identification of contamination sources within the food chain with polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzo-furans (PCDFs), (“dioxins”), and PCBs is difficult and complex. PCDD/PCDF can be formed as unintentional compounds in a number of chemical processes as well as in almost every combustion process. PCBs were intentionally produced chemicals that were manufactured for decades before the ban in marketing and use in many countries around 1985. The pattern of occurrence can change from the original source in particular via feedingstuffs to food of animal origin as result of bioaccumulation. A number of examples illustrate the challenging detective work and key scientific aspects for identification of the sources, for support of the risk management and for performance of monitoring programs. The contamination of milk and milk products in European countries with dioxins was caused by compound feeds containing citrus pulp pellets from Brazil which had high dioxin levels as a result of the use of heavily contaminated lime used for neutralization. The Belgian dioxin crisis was caused by a feed additive heavily contaminated with PCBs which were discharged into a recycled fat used in the production of animal feed. Guar gum from India was contaminated with sodium pentachlorophenate and dioxins. Clay was found to be possibly highly contaminated with dioxins possibly formed by geothermal processes over time;use of such clay as feed additive or for human intake led to elevated dioxin levels in food and humans. Bioanalytical screening in combination with comprehensive physicochemical investigations led to the detection of brominated flame retardants and brominated dioxins in a feed additive. Buffalo milk was contaminated in Italy presumably caused by illegal deposition of waste. High PCB levels in fuel oil for drying of breadcrumb used as a feed ingredient caused a major dioxin crisis with pork meat in Ireland. Fatty acids for technical purposes originating from a biodiesel company were used for production of feed fat which contaminated parts of the food chain in Germany. In addition to effects on human and animal health these incidents also have serious economic consequences which could be mitigated by more frequent control on food and feed. Addressing both these issues, the European Community has developed a strategy to reduce the presence of dioxins and PCBs in the environment and in feed and food comprising the establishment of maximum and action levels.
