S. Landsberger

Characterization of the Gent Stacked Filter Unit PM10 Sampler

ABSTRACT An integral part of several International Atomic Energy Agency sponsored coordinated research programmes involving the sampling and analysis of ambient airborne particules was the development of a PM10 sampler. Each participant was provided with such a sampler so that comparable samples would be obtained by each of the participating groups. Thus, in order to understand the characteristics of this sampler, we undertoke several characterization studies in which we examined the aerodynamic collection characteristics of the impactor inlet and the reproducibility of the sample mass collection. One of the samplers machined in Belgium was compared with one built from the same design in the U.S. and comparable results were obtained. The sampler was operated side-by-side with a commercial PM10 beta gauge and an IMPROVE-design 2.5 μm cut-point cyclone. Although the sampler was not wind tunnel tested as required for certification as a reference sampler, it does provide a collection efficiency that generally...

Arctic aerosol size‐segregated chemical observations in relation to ozone depletion during Polar Sunrise Experiment 1992

During Polar Sunrise Experiment 1992 at Alert in the Canadian high Arctic, size-fractionated observations of aerosol constituents (halogens, Na, V, As, Sb, Zn, Al, Ca, SO4=, Sm, K, Mn, and Mg) were made using a low-pressure cascade impactor and a high-volume virtual impactor (HVVI). Over 80% of the mass of V, Br, I, As, Sb, Zn, and SO4= was in particles <2.5 μm diameter. In contrast to SO4=, NO3− has more mass in larger particles. Similarly, Cl peaked in larger particles (1.72 to 6.0 μm) than Na (0.49 and 1.72 μr). Both of these effects are likely caused by reactions of sulphate acids with salts of nitrates and chloride in submicrometer particles and the volatilization of HNO3 and HCl. For fine particles (diameter <2.5 μm), observations of relatively, nonvolatile primary particulate elements (Na, V, Mn) with the two measurement devices agreed within analytical uncertainty. In contrast, they did not agree well for the more volatile halogens. The HVVI always recorded higher. Sea-salt enrichment factors of Cl (EFs s) referenced to Na for the HVVI data showed enrichment (1.2 to 1.8) in both fine and coarse aerosols during January. Thereafter, EFss averaged 0.92 and 0.57 for coarse and fine fractions, respectively, and were well correlated with each other. In contrast, EFss on fine particles collected with the cascade impactor were considerably lower (0.18 to 0.44), indicating volatilization of Cl within the device. A principal component analysis of fine particle (<2.5 μm) constituents from the HVVI identified six aerosol components consisting of anthropogenic (Mn, As, Sb, V, Zn, Al), sea salt (Cl, Na), iodine-bromine (I, Br), photochemical (Br, −O3), soil (Ca, Al), and one loaded solely by Sm. For the whole period, there was a strong anticorrelation between O3 and aerosol Br but not with the other halogens. In this study, iodine was significantly linearly correlated with the square root of the Br concentration. It showed a weak anticorrelation with O3 only after polar sunrise but not before.

Organic and inorganic bromine compounds and their composition in the Arctic troposphere during polar sunrise

Particle and gas phase inorganic bromine, total organic bromine, and several individual organic bromine species were measured in the troposphere during the Polar Sunrise Experiment at Alert, Northwest Territories, Canada, during January 18 to April 21, 1992. The measurements revealed the following: (1) Particle bromide increased gradually from about 10 ng (Br) m−3 during the dark period to >20 ng(Br) m−3 during the light period, with a marked peak of 120 ng(Br) m−3 corresponding to a strong O3 depletion event. (2) Inorganic gaseous bromine (InorgBr) was about 60 ng(Br) m−3 during the dark period and relatively constant. A major peak, up to 280 ng(Br) m−3, before sunrise accompanied a similar peak in the total organic bromine. These episodes originated in the free troposphere over Greenland. After sunrise the peaks in InorgBr corresponded to O3 depletion periods. InorgBr appeared to be the sum of HBr, HOBr, and Br2. (3) Total organic bromine was relatively constant before sunrise at 100 ng(Br) m−3 but more variable afterward, up to 280 ng(Br) m−3. Individual species include CHBr3 with levels of 7–60 ng(Br) m−3. CH2Br2, CH2ClBr, CHClBr2, and CHCl2Br levels were lower at 0.5–7.5 ng(Br) m−3. CHBr3 was the largest contributor to total organic bromine of the five species, on average accounting for 23%, while the other four species amounted to less than 5% on average. CH3Br (not measured) should contribute 44% of total organic bromine assuming a concentration of 40 ng(Br) m−3 (11 parts per trillion by volume). The remaining contribution was probably from ”missing„ species which were episodically dominant after sunrise with concentrations up to 240 ng(Br) m−3 and may include some inorganic species. All the peaks in the organic bromines after sunrise corresponded to the O3 depletion events. (4) CHBr3, CHClBr2, and CHCl2Br were significantly correlated. The ratio CHClBr2/CHBr3 decreased linearly with increasing In(CHBr3), with a steeper decrease after sunrise than before. The decreases suggest different rates of destruction with CHBr3 having a larger rate constant than CHClBr2. A similar relationship existed between the ratio CHCl2Br/CHClBr2 and the In(CHClBr2), but the dark period slope was near zero, indicating a greater difference in rates in the two species in the light period.

Lower tropospheric measurements of halogens, nitrates, and sulphur oxides during Polar Sunrise Experiment 1992

During the international Polar Sunrise Experiment 1992 at Alert, Northwest Territories, Canada, in the high Arctic, atmospheric chemistry measurements were conducted from January to April to investigate lower tropospheric ozone depletion chemistry. A series of filter-based measurements involving a denuder and multistage filter holders were made to characterize the particulate and gaseous fraction of lower tropospheric SOx., Br, Cl, I, and NO3− in relation to O3 depletion events. Bromine compounds were the only ones of all those measured to show correlations with ozone depletion. All three components of total Br (particulate inorganic, gaseous inorganic, and gaseous organic) increased during O3 depletion events. Temporal trends in halogens between the dark of January and the complete light of April were in some cases evident. Largely, as a result of more frequently occurring O3 depletion-related episodes toward April, average concentrations of Br components tended to increase. The sum of inorganic particulate and gaseous Br increased from about 10 to 20 parts per trillion by volume (pptv) and organic gaseous Br increased from 25 to 40 pptv. Total inorganic I concentrations increased from about 0.3 pptv in early March to 1.0 pptv in late April. There was no systematic trend in total inorganic (gas plus particle) Cl with concentrations averaging approximately 40 pptv, while organic Cl trapped on charcoal was much more abundant. SOx concentrations averaged about 1200 pptv, decreasing from a maximum of 6000 pptv in January to 800 pptv in April and were well correlated with anthropogenic V. The fraction of SOx oxidized to SO4= increased progressively from a low of 20 to 30% in January to greater than 80% in April. SO4= concentrations increased from 500 pptv in January/February to 1000 pptv in March and dropped to 700 pptv in April. Inorganic NO3− showed no systematic variation throughout the period. It averaged 50 pptv, which is much less than peroxyacetyl nitrate (PAN) (150 to 600 pptv), and it was predominantly in particles. Judging from denuder observations, a filter combination of Teflon followed by two KOH filters can provide useful estimates of inorganic particulate Br− and NO3− as well as of inorganic gaseous Br−. Inorganic gaseous NO3− measurements from KOH and nylon filters suffer interferences from collection of PAN.

Trace elements in snow samples from the Scottish Highlands: sources and dissolved/particulate distributions

Abstract Fresh snow samples were collected throughout a season at a high altitude (1080m) site in the NE Scottish Highlands and analysed for 14 trace elements in addition to the major element composition. Enrichment factors suggests three significant sources of the different elements, i.e. crust, seawater and anthropogenic inputs. Elements associated with anthropogenic and marine sources are in general soluble upon thawing (e.g. Br 98% dissolved) while elements from crustal sources are insoluble (e.g. Al 18% dissolved). Elements with mixed sources tend to show intermediate behaviour with average solubilities ranging from 27 to 96% for different elements. These solubilities are rationalized in terms of sources of the elements, their chemistry and the overall rainwater chemistry.

Determination of the elemental distribution in cigarette components and smoke by instrumental neutron activation analysis

Cigarette smoking is a major source of particles released in indoor environments. A comprehensive study of the elemental distribution in cigarettes and cigarette smoke has been completed. Specifically, concentrations of thirty elements have been determined for the components of 15 types of cigarettes. Components include tobacco, ash, butts, filters, and cigarette paper. In addition, particulate matter from mainstream smoke (MS) and sidestream smoke (SS) were analyzed. The technique of elemental determination used in the study is instrumental neutron activation analysis. The results show that certain heavy metals, such as As, Cd, K, Sb and Zn, are released into the MS and SS. These metals may then be part of the health risk of exposure to smoke. Other elements are retained, for the most part, in cigarette ash and butts. The elemental distribution among the cigarette components and smoke changes for different smoking conditions.

Studies of radioactivity and heavy metals in phosphate fertilizer

The enormous utilization of phosphate rock and super phosphate derived from it have the potential of being an important factor in the contamination of aquifers with alpha emitting radionuclides and heavy metals. Both rock phosphate and super phosphate contain substantial levels of natural uranium, amounting to hundreds of ppm. Our study has shown that whereas the uranium series in phosphate rock is nearly in secular equilibrium, in super phosphate the226Ra and its progeny are depleted by 60–70%. This is a result of the chemical processing of the rock phosphate. On the other hand the super phosphate is much more soluble and can be expected to release its radionuclides to the environment more rapidly than rock phosphate. The present study explores the release of radioisotopes and heavy metals from phosphate fertilizers. Extensive analytical use has been made of a germanium well-detector/Compton suppression system.

Chemical and meteorological influences on surface ozone destruction at Barrow, Alaska, during Spring 1989

Surface ozone, particulate bromine and inorganic and organic gaseous bromine species were measured at Barrow, AK, during March and April 1989 to examine the causes of surface ozone destruction during the arctic spring. Satellite images of the Alaskan Arctic taken during the same period were also studied in conjunction with calculated air mass trajectories to Barrow to investigate the possible origins of the ozone-depleted air. It was found that during major ozone depletion events (O3<25 ppbv) concentrations of particulate bromine and the organic brominated gases bromoform and dibromochloromethane were elevated. Air mass trajectories indicated that the air had crossed areas of the Arctic Ocean where leads had been observed by satellite. The transport time from the leads was typically a day or less, suggesting a fast loss mechanism for ozone. A similarly fast production of particulate bromine was shown by irradiating ambient nighttime air in a chamber with actinic radiation that approximated daylight conditions. Such rapid reactions are not in keeping with gas-phase photolysis of bromoform, but further studies showed evidence for a substantial fraction of organic bromine in the particulate phase; thus heterogeneous reactions may be important in ozone destruction.

Intra-urban precipitation quality: Hamilton, Canada

Intra-urban variability of H+ (as measured by pH) along with S, halogens and heavy metals are studied in bulk precipitation from a network of 11 collectors located in the city of Hamilton, Canada. Bulk precipitation is shown a useful indicator of both elemental intra-urban variability and sources. Precipitation acidity is an order of magnitude less within urban areas than of that measured outside the city. Bulk depositional characteristics are classified into three distinct patterns as influenced by industrial emissions (Cu, Cl, Fe, Mn, and V), urban sediments (Ca and Mg), and automobile emissions (Br and Pb). A substantial component of S and Zn loadings are attributed to anthropogenic sources from outside the city while a substantial component of Al, I, and Na loadings are attributed to natural sources.

Source-Receptor Modeling Using Trace Metals in Aerosols Collected at Three Rural Canadian Great Lakes Sampling Stations

High-volume air samplers were used to collect aerosol samples on Whatman 41 air filters at the Canadian air sampling stations Burnt Island, Egbert, and Point Petre. The samples were analyzed for trace elements by neutron activation analysis. Air concentrations of over 30 trace elements were determined. Factor analysis, elemental ratios, and enrichment factor analysis were used to determine source-receptor relationships at the three different sites. Factor analysis exhibited trends that indicate oil and coal combustion, road salt, mining, incineration, and smelting as anthropogenic sources to aerosols of the rural Great Lakes. Elemental ratios showed that the Na to Cl ratio in the Great Lakes aerosol is similar to that found in sea water. Enrichment factor analysis revealed elements with non-crustal sources including the elements Ag, As, Br, Cl, Cu, I, In, Sb, Se, Sn, W, and Zn.