Ulla Wideqvist

Chemical and physical characterization of emissions from birch wood combustion in a wood stove.

The purpose of this study was to characterize the emissions of a large number of chemical compounds emitted from birch wood combustion in a wood stove. Birch wood is widely used as fuel in Swedish household appliances. The fuel load was held constant during six experiments. Particles < 2.5 mum diameter were collected and the size distribution of the particles was measured. The results were compared to the size distribution in road traffic emissions. It could be seen that the number distribution differed between the sources. In traffic exhaust, the number of particles maximized at 20 nm, while the number distribution from wood burning ranged from 20 to 300 nm. The ratio K/Ca on particles was found. to be significantly different in wood burning compared to road dust, range 30-330 for the former and 0.8+/-0.15 for the latter. The source profile of common elements emitted from wood-burning differed from that found on particles at a street-level site or in long-distance transported particles. The ratio toluene/benzene in this study was found to be in the range 0.2-0.7, which is much lower than the ratio 3.6+/-0.5 in traffic exhaust emissions. Formaldehyde and acetone were the most abundant compounds among the volatile ketones and aldehydes. The emission factor varied between 180-710mg/kg wood for formaldehyde and 5-1300mg/kg wood for acetone. Of the organic acids analyzed (3,4,5)-trimethoxy benzoic acid was the most abundant compound. Of the PAHs reported, fluorene, phenanthrene, anthracene, fluoranthene and pyrene contribute to more than 70% of the mass of PAH. Of the elements analyzed, K and Si were the most abundant elements, having emission factors of 27 and 9mg/kg wood, respectively. Although fluoranthene has a toxic equivalence factor of 5% of benzo(a)pyrene (B(a)P), it can be seen that the toxic potency of fluoranthene in wood burning emissions is of the same size as B(a)P. This indicates that the relative carcinogenic potency contribution of fluoranthene in wood smoke would be about 40% of B(a)P

Spatial differences and temporal trends of organochlorine compounds in biota from the northwestern hemisphere

Tissues of animal species from various trophic levels in the northwestern hemisphere were collected and analyzed for the presence of polychlorinated camphenes (PCC,e.g. toxaphene), DDT and its metabolites DDD and DDE (σDDT) and polychlorinated biphenyls (PCB) to elucidate differences in geographical distribution, biomagnification and temporal trends. Many of the samples were also analyzed for the presence of chlordane. The previously achieved knowledge of DDT and PCB contamination was used as a yardstick for characterizing the exposure regime of the other organochlorine compounds.No pronounced geographical differences were found for PCC when comparing animals from the Arctic region with corresponding species in the Baltic, while both PCB and σDDT showed definite spatial differences. The highest concentrations of σDDT and PCB were found in fish predators,i.e., raptorial birds and seals, from the Baltic. PCC levels in fish exceed levels of σDDT and PCB in the North Atlantic and the PCC levels in Swedish fish are as high as or higher than the σDDT levels. While the σDDT and PCB levels for all trophic levels range from 0.14–990 mg/kg fat, the corresponding range for PCC is only 0.33–17 mg/kg. This indicates less biomagnification of PCC and/or a more effective metabolism of PCC, compared with σDDT and PCB, at high trophic levels. The levels of σDDT and PCB in Swedish fish and birds show a decrease during the late seventies and the beginning of the eighties. For the PCC levels, however, no distinct trends could be discerned during the same period in any of the areas studied.

Analysis of Toxaphene (PCC) and Chlordane in Biological Samples by NCI Mass Spectrometry

Several recent reports indicate that both toxaphene (polychlorocamphene, PCC) and chlordane are widespread pollutants in our environment. These insecticides, both complex mixtures of chlorinated hydrocarbons, are difficult to separate from each other. Thus the analyses of them in environmental samples are difficult and furthermore complicated by interferences from other chlorinated hydrocarbons such as PCB and DDT compounds. Mass fragmentography using the negative ions formed by chemical ionization proved to be useful to selectively detect the toxaphenes and the chlordanes without interferences from DDT. High concentrations of PCB still influence on the results and have to be removed in the clean-up procedure.

Determination of nonylphenol and nonylphenol ethoxylates as their pentafluorobenzoates in water, sewage sludge and biota

Abstract A method has been developed for the determination of nonylphenol and nonylphenol ethoxylates containing one to three ethoxy units in water, sludge and biota. After isolation the substances are converted into their corresponding pentafluorobenzoyl derivatives and quantified by GC/ECD or GC/MS. Results from investigations of secondary sludge from eight municipal sewage treatment plants in Sweden revealed concentrations of 4-nonylphenol from 26 to 1100 mg/kg d.m. An uptake study on blue mussels ( Mytilus edulis ) was carried out near the waste water outlet of a manufacturer of nonylphenol ethoxylates. The concentrations of 4-nonylphenol in the mussels ranged from 0.20 to 0.40 μg/g wet weight.

Comparison of measurement methods for benzene and toluene

Abstract Diffusive sampling and active (pumped) sampling (tubes filled with Tenax TA or Carbopack B) were compared with an automatic BTX instrument (Chrompack, GC/FID) for measurements of benzene and toluene. The measurements were made during differing pollution levels and different weather conditions at a roof-top site and in a densely trafficked street canyon in Stockholm, Sweden. The BTX instrument was used as the reference method for comparison with the other methods. Considering all data the Perkin–Elmer diffusive samplers, containing Tenax TA and assuming a constant uptake rate of 0.406 cm 3 min −1 , showed about 30% higher benzene values compared to the BTX instrument. This discrepancy may be explained by a dose-dependent uptake rate with higher uptake rates at lower dose as suggested by laboratory experiments presented in the literature. After correction by applying the relationship between uptake rate and dose as suggested by Roche et al. (Atmos. Environ. 33 (1999) 1905), the two methods agreed almost perfectly. For toluene there was much better agreement between the two methods. No sign of a dose-dependent uptake could be seen. The mean concentrations and 95% confidence intervals of all toluene measurements (67 values) were (10.80±1.6) μg m −3 for diffusive sampling and (11.3±1.6) μg m −3 for the BTX instrument, respectively. The overall ratio between the concentrations obtained using diffusive sampling and the BTX instrument was 0.91±0.07 (95% confidence interval). Tenax TA was found to be equal to Carbopack B for measuring benzene and toluene in this concentration range, although it has been proposed not to be optimal for benzene. There was also good agreement between the active samplers and the BTX instrument.

The evaluation of an analytical method for polychlorinated terpenes (PCC) in biological samples using an internal standard

Abstract The quantitative analysis of PCC (Toxaphene) residues in biological samples using gas chromatography with electron capture detection has been evaluated. Dechlorane 603, a chloroalicyclic compound is used as internal standard and modifications of the injection system for proper evaporation of this high-boiling compound is described. In the cleanup procedure PCB (and 1 – 3 % of the PCC) are removed by adsorption chromatography. Chlordane components and DDT compounds remaining in the PCC fraction constitute 5 – 10 % and 13 – 16 %, respectively, of the peak area in the chromatograms of the samples investigated. The quantitative results are influenced by the number of PCC-peaks chosen for the calculations and have to be specified together with the PCC-levels reported. The recoveries of PCC from spiked samples (20 ug PCC per gram crude fat above “natural” level) are 61 – 98 %, the lower figures obtained with samples containing low levels of PCC-residues. The practical limit of detection is about 10 ng PCC per g extracted fat.

Extensive organohalogen contamination in wildlife from a site in the Yangtze River Delta.

The environmental and human health concerns for organohalogen contaminants (OHCs) extend beyond the 23 persistent organic pollutants (POPs) regulated by the Stockholm Convention. The current, intense industrial production and use of chemicals in China and their bioaccumulation makes Chinese wildlife highly suitable for the assessment of legacy, novel and emerging environmental pollutants. In the present study, six species of amphibians, fish and birds were sampled from paddy fields in the Yangtze River Delta (YRD) were screened for OHCs. Some extensive contamination was found, both regarding number and concentrations of the analytes, among the species assessed. High concentrations of chlorinated paraffins were found in the snake, Short-tailed mamushi (range of 200-340 μg g(-)(1)lw), Peregrine falcon (8-59 μg g(-1)lw) and Asiatic toad (97 μg g(-)(1)lw). Novel contaminants and patterns were observed; octaCBs to decaCB made up 20% of the total polychlorinated biphenyls (PCBs) content in the samples and new OHCs, substituted with 5-8 chlorines, were found but are not yet structurally confirmed. In addition, Dechlorane 602 (DDC-DBF) and numerous other OHCs (DDTs, hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs), hexbromocyclododecane (HBCDD), chlordane, heptachlor, endosulfan and Mirex) were found in all species analyzed. These data show extensive chemical contamination of wildlife in the YRD with a suite of OHCs with both known and unknown toxicities, calling for further in-depth studies.

Surface Partitioning in Organic-Inorganic Mixtures Contributes to the Size-Dependence of the Phase-State of Atmospheric Nanoparticles

Atmospheric particulate matter is one of the main factors governing the Earths radiative budget, but its exact effects on the global climate are still uncertain. Knowledge on the molecular-scale surface phenomena as well as interactions between atmospheric organic and inorganic compounds is necessary for understanding the role of airborne nanoparticles in the Earth system. In this work, surface composition of aqueous model systems containing succinic acid and sodium chloride or ammonium sulfate is determined using a novel approach combining X-ray photoelectron spectroscopy, surface tension measurements and thermodynamic modeling. It is shown that succinic acid molecules are accumulated in the surface, yielding a 10-fold surface concentration as compared with the bulk for saturated succinic acid solutions. Inorganic salts further enhance this enrichment due to competition for hydration in the bulk. The surface compositions for various mixtures are parametrized to yield generalizable results and used to explain changes in surface tension. The enhanced surface partitioning implies an increased maximum solubility of organic compounds in atmospheric nanoparticles. The results can explain observations of size-dependent phase-state of atmospheric nanoparticles, suggesting that these particles can display drastically different behavior than predicted by bulk properties only.

Hygroscopic growth and cloud forming potential of Arctic aerosol based on observed chemical and physical characteristics (a 1 year study 2007–2008)

Aerosol particle samples were collected, and the particle size distribution was measured during 1 year at the Zeppelin station (474 m asl) on Svalbard. The chemical constituents, hygroscopicity, and cloud forming properties of the aerosol were analyzed. The aerosol contained mostly sulfate and nitrate during the summer, whereas from September to February the main components were sodium and chloride. The highest concentration (20%) of water-soluble organic matter was sampled in December. The hygroscopic growth factors for the water-soluble fraction were 1.56-2.01 at 90% relative humidity, peaking in October, when the measured supersaturations needed for cloud drop formation were also the lowest. Sea-salt components showed a positive correlation with the cloud forming capability, whereas the organic content had no correlation. The hygroscopicity factors, or kappa values, were determined in three ways for each month: (1)kappa(H-TDMA) from measurements of the hygroscopic growth of particles produced from atomization of the filter extracts, (2)kappa(CCNC) from measurements of the critical supersaturation as a function of size for these particles, and (3)kappa(chem) was modeled based on the organic and inorganic composition of the filter samples. Using the measured particle size distributions and the critical activation diameters from the Cloud Condensation Nuclei Counter (CCNC) measurements, it was found that the number of CCN varied more with supersaturation during the summer months. The best agreement between all three kappa values was in December and January. Comparisons with earlier studies do not suggest any trend in the Arctic aerosol seasonal variability over the last decade.

Chemical composition and source analysis of carbonaceous aerosol particles at a mountaintop site in central Sweden

Abstract The chemical composition of atmospheric particulate matter at Mt. Åreskutan, a mountaintop site in central Sweden, was analysed with a focus on its carbonaceous content. Filter samples taken during the Cloud and Aerosol Experiment at Åre (CAEsAR 2014) were analysed by means of a thermo-optical method and ion chromatography. Additionally, the particle light absorption and particle number size distribution measurements for the entire campaign were added to the analysis. Mean airborne concentrations of organic and elemental carbon during CAEsAR 2014 were OC = 0.85 0.80 g m and EC = 0.06 0.06 g m, respectively. Elemental to organic carbon ratios varied between EC/OC = 0.02 and 0.19. During the study a large wildfire occurred in Västmanland, Sweden, with the plume reaching our study site. This led to significant increases in OC and EC concentrations (OC = 3.04 0.03 g m and EC = 0.24 0.00 g m). The mean mass-specific absorption coefficient observed during the campaign was = 9.17.3 mg (at wavelength = 637 nm). In comparison to similarly remote European sites, Mt. Åreskutan experienced significantly lower carbonaceous aerosol loadings with a clear dominance of organic carbon. A mass closure study revealed a missing chemical mass fraction that likely originated from mineral dust. Potential regional source contributions of the carbonaceous aerosol were investigated using modelled air mass back trajectories. This source apportionment pointed to a correlation between high EC concentrations and air originating from continental Europe. Particles rich in organic carbon most often arrived from highly vegetated continental areas. However, marine regions were also a source of these aerosol particles. The source contributions derived during this study were compared to emission inventories of an Earth system model. This comparison highlighted a lack of OC and EC point-sources in the model’s emission inventory which could potentially lead to an underestimation of the carbonaceous aerosol reaching Mt. Åreskutan in the simulation of this Earth system model.