Stellan Marklund

Overview on environmental fate of chlorinated dioxins and dibenzofurans. Sources, levels and isomeric pattern in various matrices

Abstract Polychlorinated dioxins and dibenzofurans have been identified in technical products and pesticides, most of which are not very widely used today. Other sources are incinerators of various types like MSW incinerators, but also hazardous waste incinerators and industrial incinerators. PCDDs and PCDFs have also been identified in exhausts from cars running on leaded gasoline with halogenated additives. Background levels of PCDDs and PCDFs have been identified in fish and other aquatic organisms from the Great Lakes and the Baltic Sea, and also in human adipose tissue samples from USA, Canada, Sweden, Japan and Viet Nam as well as in samples of breast milk from Sweden, Denmark, West Germany, the Netherlands, Yugoslavia and Viet Nam. The isomeric pattern in all these biological samples is very similar.

Removal of dioxins and related aromatic hydrocarbons from flue gas streams by adsorption and catalytic destruction

The dioxin removing capacity of the shell dedioxin system (SDDS-a Ti/V oxidative type catalyst) has been tested using the Umeå lab-scale incinerator over the temperature range 100-230 degrees C and at space velocities of 8000 and 40,000 h(-1). Other analogous organic compounds, such as PCBs, PAHs, chlorobenzenes and chlorophenols have also been investigated. Results show a high degree of dioxin removal already at 100 degrees C (82%), which occurs mainly by adsorption. When the temperature is raised a transition towards destruction is seen and at 150 degrees C, gas hour space velocity (GHSV) 8000 and at 230 degrees C, GHSV 40,000 virtually all removal is by destruction. High PCDD/F destruction efficiencies are reported (> 99.9%, based on I-TEQ); the other dioxin-related species and PAHs are also removed and destroyed to a significant extent. The SDDS has proved to be an effective means of destroying organic compounds in the gas phase, particularly dioxins, at temperatures as low as 150 degrees C.

Emissions of PCDDs and PCDFs in gasoline and diesel fueled cars

Polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) have been identified in automobile exhaust from cars running on leaded and unleaded gasoline respectively. The chlorine concentrations in the fuels are in the ppm range and involved in the formation of PCDDs and PCDFs. However no chlorine was detected in the diesel oil, and the emission of PCDDs and PCDFs from a diesel fueled truck was lower than the detection level (<100 pg/liter diesel).

Formation and chlorination of polychlorinated naphthalenes (PCNs) in the post-combustion zone during MSW combustion

Non- to octa-chlorinated naphthalenes (PCNs) were analyzed in flue gas samples collected simultaneously at three different temperatures (450 degrees C, 300 degrees C and 200 degrees C, respectively) in the post-combustion zone during waste combustion experiments using a laboratory-scale fluidized-bed reactor. PCN homologue profiles in all samples were dominated by the lower chlorinated homologues (mono- to triCN), with successive reductions in abundance with each additional degree of chlorination. The isomer distribution patterns reflected ortho-directionality behavior of the first chlorine substituent, and the beta-positions, i.e. the 2,3,6,7-substitution sites, seemed to be favored for chlorination. Injection of naphthalene into the post-combustion zone resulted in increased PCN levels at 200 degrees C, demonstrating the occurrence of chlorination reactions in the post-combustion zone. However, the increases were restricted to the least-chlorinated homologue (monoCN), probably because there was insufficient residence time for further chlorination. In addition, an episode of poor combustion (manifested by high CO levels) was accompanied by extensive formation of 1,8-diCN, 1,2,3- and 1,2,8-triCN; congeners with substitution patterns that are not thermodynamically favorable. These are believed to be products of PAH breakdown reactions and/or chlorophenol condensation. Overall, PCN formation is likely to occur via more than one pathway, including chlorination of naphthalene that is already present, de novo synthesis from PAHs and, possibly, chlorophenol condensation.

The influence of level and chlorine source on the formation of mono- to octa-chlorinated dibenzo-p-dioxins, dibenzofurans and coplanar polychlorinated biphenyls during combustion of an artificial municipal waste

The formation of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and the three coplanar polychlorinated biphenyls (pPCBs) was studied during labscale fludized bed combustion of eight artificial municipal solid waste (MSW) fuel mixtures. The level of chlorine as well as the chlorine source varies within the different fuel mixtures. Four different chlorine sources were studied, viz, an inorgnaic (NaCl) and three organic sources, pure PVC plastic and two products (floor and cable) and the total chlorine level varies between 0.28% and 1.1%. The experiments were performed in a 5 kW laboratory scale fluidized bed reactor. A correlation between the total chlorine in the fuel and the formation of the hepta- and octa-chlorinated PCDD/F homologues was found. However, the most important variable for changes in the PCDDs/Fs and pPCBs formation was disturbance in the combustion condition and not the variation in chlorine content of the fuel. Furthermore, no differences in formation between the chlorine sources could be seen.

Emissions of unintentional persistent organic pollutants from open burning of municipal solid waste from developing countries

Open burning of waste is the most significant source of polychlorinated dibenzo-para-dioxins and dibenzofurans (PCDD/PCDF) in many national inventories prepared pursuant to the Stockholm Convention on Persistent Organic Pollutants. This is particularly true for developing countries. Emission factors for POPs such as PCDD/PCDF, dioxin-like polychlorinated biphenyls (dl-PCB) and penta- and hexachlorobenzenes (PeCBz/HCB) from open burning of municipal solid waste in China and Mexico are reported herein. Six different waste sources were studied varying from urban-industrial to semi-urban to rural. For PCDD/PCDF, the emission factors to air ranged from 3.0 to 650 ng TEQ kg(-1)waste and for dl-PCB from 0.092 to 54 ng TEQ kg(-1)waste. Emission factors for PeCBz (17-1200 ng kg(-1)waste) and HCB (24-1300 ng kg(-1)waste) spanned a wide but similar range. Within the datasets there is no indication of significant waste composition effect on emission factor with the exception of significantly higher Mexico rural samples.

Effects of oxygen on formation of PCB and PCDD/F on extracted fly ash in the presence of carbon and cupric salt

The effect of oxygen-nitrogen atmosphere (N2 + 10%O2, N2 + 1%O2 and 99.999% N2) on the formation of PCB, PCDD and PCDF by the de novo synthetic reactions in the system consisting of extracted fly ash (from municipal waste incinerators--MWI), activated carbon, CuCl2 x 2H2O and NaCl at 340 degrees C was studied. The content of PCDD/F for systems with 10%O2, 1%O2 and 99.999% N2 was decreasing and corresponded to 17,304, 5544, and 1437 ng/sample. In all studied systems the isomer OCDD/F was prevailing. The content of PCBs in the same system was also decreasing from 1214 to 166 ng/g. Formation of nonortho PCB was relatively high compared to the system where only nitrogen was present. The possible mechanism of formation is outlined.

The effect of oils on PAH, PCDD, PCDF, and PCB emissions from a spark engine fueled with leaded gasoline

The effect of synthetic and mineral oils on the formation of polyaromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) in emissions from a spark ignition engine was studied on a Skoda Favorit engine fueled with leaded gasoline. The test cycle simulated urban traffic conditions on a chassis dynamometer, in accordance with the ECC 83.00 test. The data for selected PAHs as well as PCDDs, PCDFs, and PCBs congener profiles are presented. PCDD/Fs emissions for an unused oil and the oil after 10000-km operation varied from 300 to 2000 fmol/m3, PCBs emissions from 75 to 178 pmol/m3, and PAHs emissions from 150 to 420 microg/m3. The content of PCBs in oils varied from 2 to 920 mg/kg.

HEPATOMAS AND OTHER NEOPLASMS IN THE ATLANTIC HAGFISH (MYXINE GLUTINOSA): A HISTOPATHOLOGIC AND CHEMICAL STUDY*

M. glutinosa is a cyclostome, living in the mud in seawater of high salinity. It probably is a stationary scavenger feeder. About 28,000 hagfish from the Gullmar Fjord were examined during a 5-year period for the occurrence of tumors. Hepatomas were found to be predominant neoplasm, observed at a frequency that decreased from 5.8% in 1972 to 2.9% in 1973 and finally to 0.6% in 1974--76. Islet cell hamartomas and frank neoplasms decreased from 0.5% in 1972 to less than 0.1% in 1973--76. Occasional subcutaneous and mesenterial neoplasms were also observed during 1972--74. In hagfish caught 12 km out in the open sea, the hepatoma incidence decreased from 2.8% in 1972 to 0.9% in 1974. Given this background, it is possible that pollution of the Gullmar Fjord by carcinogenic substances with low biodegradability has occurred until 1972, and this pollution could be of etiologic significance for these hagfish tumors. In fact, the use of PCBs became prohibited by law in Sweden in 1971--72. Severe restrictions were also introduced for the use of chlorinated pesticides, notably DDT, and associated substances (DDD, DDE). Preliminary analyses for the presence of PCBs, DDT (and its metabolites), and aflatoxins (the notorious hepatocarcinogen) were performed by gas chromatography and thin-layer chromatography. Livers (with and without neoplasms) from hagfish caught inside the threshold of the fjord contained about 5 mg/kg of wet weight of PCBs and about 0.1--0.4 mg/kg of dry weight of DDT, DDD, or DDE, whereas those from hagfish caught in the open sea had a much lower PCB concentration (about 0.2 mg/kg of wet weight). No PCBs and no chlorinated pesticides were found in analyses of the mud at the catching site. High PCB concentrations (3 mg/kg of wet weight) were, however, observed in livers from cod living in the Gullmar Fjord, and it was proposed that bony fish may be the source of hagfish liver PCBs. PCB chromatograms of hagfish livers differed from those of PCB standards and cod liver. This strange pattern, which was not seen in livers from hagfish caught in the open sea, might be explained by an unusual mode of metabolization. The assays for aflatoxins gave completely negative results.

Design of a laboratory scale fluidized bed reactor

The aim of this project was to construct a laboratory scale fluidized bed reactor that simulates the behavior of full scale municipal solid waste combustors. The design of this reactor is thoroughly described. The size of the laboratory scale fluidized bed reactor is 5 kW, which corresponds to a fuel-feeding rate of approximately 1 kg/h. The reactor system consists of four parts: a bed section, a freeboard section, a convector (postcombustion zone), and an air pollution control (APC) device system. The inside diameter of the reactor is 100 mm at the bed section and it widens to 200 mm in diameter in the freeboard section; the total height of the reactor is 1760 mm. The convector part consists of five identical sections; each section is 2700 mm long and has an inside diameter of 44.3 mm. The reactor is flexible regarding the placement and number of sampling ports. At the beginning of the first convector unit and at the end of each unit there are sampling ports for organic micropollutants (OMP). This makes ...