Mattias Hallquist

Roadside measurements of fine and ultrafine particles at a major road north of Gothenburg

The general population is exposed to particulate air pollution from many different local and regional sources. Examples of local sources are traffic, biomass burning and resuspended dust, while regional sources are dominated by combustion processes from heating, traffic and industries. The overall aim of this thesis was to characterise the personal exposure to trace elements in fine particles, mainly PM2.5 and investigate how the exposure is related to indoor and outdoor levels. Particulate matter was collected on filters and analysed for elemental content by X-ray fluorescence (XRF) spectroscopy. In the general population in Goteborg, personal exposures to Cl, Ca, Ti and Fe were significantly higher compared with indoor, residential outdoor and urban background levels. Significant correlations were also found between urban background PM mass and personal exposure to elements related to both combustion (S, V and Pb) and resuspended dust (Ti, Fe and Zn), indicating that both sources could be relevant for health effects from urban background PM. In a community where wood burning for domestic heating is common, significantly (66-80%) higher personal exposures and indoor levels were found for K, Ca and Zn compared with a reference group living in the same area, indicating that these elements could be good markers for wood smoke. In a study in Stockholm concerning childrens environments (home, school and preschool), higher indoor than outdoor levels of Ti were found, while long-range-transported (LRT) elements (S, Ni, Br and Pb) were higher outdoors. A community located 25 km from the city centre had significantly lower outdoor levels of crustal and traffic-related elements compared with both the city centre and a suburban area. The levels of Fe and Cu were four times higher in the central communities. Outdoors, Cu levels were found to correlate well with the traffic marker NO2, making it a possible elemental marker for traffic-related aerosols in health studies. Roadside measurements of fine and ultrafine (<100 nm) particles were performed along a major approach road to Goteborg and the levels of ultrafine particles were influenced not only by traffic intensity, but also, by wind speed and direction, as well as boundary layer height. No correlation was found between PM2.5 and ultrafine particles or traffic, but there was a correlation between PM2.5 and particles sized 100-368 nm. In all environments studied, the origin of LRT air masses had a strong effect on exposure and levels of PM elements. In conclusion, this thesis demonstrates that elemental analysis is a useful method for better characterising human exposure to fine particles. For several elements, the personal exposure is often higher than corresponding indoor levels. The origin of LRT elements affected not only outdoor levels, but also, the personal exposure and indoor levels, and should be taken into account in time series studies of air pollution and health.Abstract Particle measurements were conducted at a road site 15xa0km north of the city of Gothenburg for 3 weeks in June 2000. The size distribution between 10 and 368xa0nm was measured continuously by using a differential mobility particle sizer (DMPS) system. PM2.5 was sampled on a daily basis with subsequent elemental analysis using EDXRF-spectroscopy. The road is a straight four-lane road with a speed limit of 90xa0kph. The road passing the site is flat with no elevations where the vehicles run on a steady workload and with constant speed. The traffic intensity is about 20,000 cars per workday and 13,000 vehicles per day during weekends. The diesel fuel used in Sweden is low in sulphur content (

On the Gas Phase Reactions Between Volatile Biogenic Mercury Species and the Nitrate Radical

Tropospheric mercury is dominated by gas phase species. In this paper, the gas phase reactions between the nitrate radical and volatile biogenic mercury species have been investigated. An upper limit for the gas phase rate coefficient for reaction between elemental mercury and NO3-radicals was determined to 4 × 10−15 cm3 molecule−1 s−1 by using the fast flow-discharge technique. The reaction between dimethyl mercury and NO3, previously shown to be rapid, has also been studied in the laboratory with respect to product distribution using FT-IR. The result from the product study is consistent with a transformation of dimethyl mercury into inorganic, divalent mercury. All carbon delivered as dimethyl mercury was transformed into formaldehyde, methanol and methyl peroxynitrate. Hg was observed as a minor (≈2%) product. By exclusion, HgO is proposed as the mercury-containing product. Thus, the reaction between dimethyl mercury and the nitrate radical is excluded as a source of monomethyl mercury species in the atmosphere.

Rates of reaction between the nitrate radical and some unsaturated alcohols

Rate coefficients for nitrate radical gas-phase reactions with prop-2-en-l-ol (allyl alcohol), but-1-en-3-ol, and 2-methylbut-3-en-2-ol have been determined. Both absolute (fast flow discharge with diode laser detection of NO3) and relative (batch reactor and FTIR spectroscopy) rate techniques were used to measure the rate coefficients. The rate coefficients at 294 K are: (1.3 ± 0.2) × 10−14, (1.2 ± 0.3) × 10 −14, and (2.1 ± 0.3) × 10−14 cm3 molecule−1 s−1 for prop-2-en-1-ol, but-1-en-3-ol, and 2-methylbut-3-en-2-ol, respectively. The activation energy for reaction of NO3 with prop-2-en-1-ol was determined to 2.8 ± 2.5 kJ mol−1 in the temperature range between 273 and 363 K. The atmospheric importance of unsaturated alcohols and structure-reactivity considerations are also discussed.

Vertical distribution of air pollutants at the Gustavii Cathedral in Göteborg, Sweden

Abstract Atmospheric trace gases and particles were measured at two heights at the Gustavii Cathedral in Goteborg, Sweden, during 7 weeks in September and October 1999. The Gustavii Cathedral is situated in the city centre of Goteborg, which is near the harbour area and encircled by heavy traffic some hundred metres away. The main body of the church is as high as the surrounding buildings, while the tower extends well above. The sampling points were placed on the west wall of the tower at 10 and 32 m height, i.e. well below and above the roof top level of surrounding buildings, respectively. Sulphur dioxide and nitric acid were sampled using the denuder technique and analysed by Ion Chromatography, IC. Total suspended particulates (TSP) were sampled using filter cups and subsequently analysed by energy dispersive X-ray fluorescence spectroscopy (EDXRF). In addition to the diurnal sampling of species, nitrogen oxides were measured using chemiluminescence detectors. Additional data from the Environmental Office in Goteborg was used in the analysis. Differences between the concentrations measured at the upper and lower levels were calculated and their variation and dependence on meteorological factors were evaluated. On the average larger concentrations were found at the lower level for soil derived elements and TSP, while nitric acid and nitric oxide showed larger concentrations at the upper level. Sulphur dioxide and nitrogen dioxide, as well as many of the elements in the TSP, showed equal concentrations at the two levels. However, depending on wind direction the measured differences of nitrogen oxides could be both positive and negative.

A kinetic study of chlorine radical reactions with ketones by laser photolysis technique

Rate coefficients for reactions between CI radicals and four ketones were determined at 294 +/- 1 K with a relative rate method using a laser photolysis technique. The experiments were conducted in ...

Optoacoustic Lead-Salt Diode Laser Detection of Trace Species in a Flow System

An experimental setup for kinetic and product studies in a flow system has been developed. For detection, a nonresonant optoacoustic technique combined with a tunable lead-salt diode laser has been employed. The performance of the system was tested on ammonia in argon, and a detection limit (S/N = 2) of 8 × 1012 molecules cm−3 (corresponding to 320 ppb at atmospheric pressure) was obtained at a pressure of about 7 kPa when frequency modulation was employed. At 1.5 kPa the detection limit was about 2 × 1014 molecules cm−1. With a multipass cell the sensitivity was increased by a factor of four.