Biomass burning started to attract attention since the last decade because of its impacts on the atmosphere and the environmental air quality, as well as significant potential effects on human health and global climate change. Knowledge of particle emission characteristics from biomass burning is crucially important for the quantitative assessment of the potential impacts. This thesis presents the results of study aimed towards comprehensive characterization of particle emissions from biomass burning. The study was conducted both under controlled laboratory conditions, to quantify the particle size distribution and emission factors by taking into account various factors which may affect the particle characteristics, and in the field, to investigate biomass burning processes in the real life situations and to examine vertical profile of particles in the atmosphere. To simulate different environmental conditions, a new technique has been developed for investigating particle emissions from biomass burning in the laboratory. As biomass burning may occur in a field at various wind speeds and burning rates, the technique was designed to allow adjustment of the flow rates of the air introduced into the chamber, in order to control burning under different conditions. In addition, the technique design has enabled alteration of the high particle concentrations, allowing conducting measurements with the instrumentations that had the upper concentration limits exciding the concentrations characteristic to the biomass burning. The technique was applied to characterize particle emissions from burning of several tree species common to Australian forests. The aerosol particles were characterized in terms of size distribution and emission factors, such as PM2.5 particle mass emission factor and particle number emission factor, under various burning conditions. The characteristics of particles over a range of burning phases (e.g., ignition, flaming, and smoldering) were also investigated. The results showed that particle characteristics depend on the type of tree, part of tree, and the burning rate. In particular, fast burning of the wood samples produced particles with the CMD of 60 nm during the ignition phase and 30 nm for the rest of the burning process. Slow burning of the wood samples produced large particles with the CMD of 120 nm, 60 nm and 40 nm for the ignition, flaming and smoldering phases, respectively. The CMD of particles emitted by burning the leaves and branches was found to be 50 nm for the flaming phase and 30 nm for the smoldering phase, under fast burning conditions. Under slow burning conditions, the CMD of particles was found to be between 100 to 200 nm for the ignition and flaming phase, and 50 nm for the smoldering phase. For fast burning, the average particle number emission factors were between 3.3 to 5.7 x 1015 particles/kg for wood and 0.5 to 6.9 x 1015 particles/kg for leaves and branches. The PM2.5 emission factors were between 140 to 210 mg/kg for wood and 450 to 4700 mg/kg for leaves and branches. For slow burning conditions, the average particle number emission factors were between 2.8 to 44.8 x 1013 particles/kg for wood and 0.5 to 9.3 x 1013 particles/kg for leaves and branches, and the PM2.5 emissions factors were between 120 to 480 mg/kg for wood and 3300 to 4900 mg/kg for leaves and branches. The field measurements were conducted to investigate particle emissions from biomass burning in the Northern Territory of Australia over dry seasons. The results of field studies revealed that diameters of particles in ambient air emissions were within the size range observed during laboratory investigations. The laboratory measurements found that the particles released during the controlled burning were of a diameter between 30 and 210 nm, depending on the burning conditions. Under fast burning conditions, smaller particles were produced with a diameter in the range of 30 to 60 nm, whilst larger particles, with a diameter between 60 nm and 210 nm, were produced during slow burning. The airborne field measurements of biomass particles found that most of the particles measured under the boundary layer had a CMD of (83 ± 13) nm during the early dry season (EDS), and (127 ± 6) nm during the late dry season (LDS). The characteristics of ambient particles were found to be significantly different at the EDS and the LDS due to several factors including moisture content of vegetation, location of fires related to the flight paths, intensity of fires, and burned areas. Specifically, the investigations of the vertical profiles of particles in the atmosphere have revealed significant differences in the particle properties during early dry season and late dry season. The characteristics of particle size distribution played a significant role in these differences.

Emissions from airport operations are of significant concern because of their potential impact on local air quality and human health. The currently limited scientific knowledge of aircraft emissions is an important issue worldwide, when considering air pollution associated with airport operation, and this is especially so for ultrafine particles. This limited knowledge is due to scientific complexities associated with measuring aircraft emissions during normal operations on the ground. In particular this type of research has required the development of novel sampling techniques which must take into account aircraft plume dispersion and dilution as well as the various particle dynamics that can affect the measurements of the aircraft engine plume from an operational aircraft. In order to address this scientific problem, a novel mobile emission measurement method called the Plume Capture and Analysis System (PCAS), was developed and tested. The PCAS permits the capture and analysis of aircraft exhaust during ground level operations including landing, taxiing, takeoff and idle. The PCAS uses a sampling bag to temporarily store a sample, providing sufficient time to utilize sensitive but slow instrumental techniques to be employed to measure gas and particle emissions simultaneously and to record detailed particle size distributions. The challenges in relation to the development of the technique include complexities associated with the assessment of the various particle loss and deposition mechanisms which are active during storage in the PCAS. Laboratory based assessment of the method showed that the bag sampling technique can be used to accurately measure particle emissions (e.g. particle number, mass and size distribution) from a moving aircraft or vehicle. Further assessment of the sensitivity of PCAS results to distance from the source and plume concentration was conducted in the airfield with taxiing aircraft. The results showed that the PCAS is a robust method capable of capturing the plume in only 10 seconds. The PCAS is able to account for aircraft plume dispersion and dilution at distances of 60 to 180 meters downwind of moving a aircraft along with particle deposition loss mechanisms during the measurements. Characterization of the plume in terms of particle number, mass (PM2.5), gaseous emissions and particle size distribution takes only 5 minutes allowing large numbers of tests to be completed in a short time. The results were broadly consistent and compared well with the available data. Comprehensive measurements and analyses of the aircraft plumes during various modes of the landing and takeoff (LTO) cycle (e.g. idle, taxi, landing and takeoff) were conducted at Brisbane Airport (BNE). Gaseous (NOx, CO2) emission factors, particle number and mass (PM2.5) emission factors and size distributions were determined for a range of Boeing and Airbus aircraft, as a function of aircraft type and engine thrust level. The scientific complexities including the analysis of the often multimodal particle size distributions to describe the contributions of different particle source processes during the various stages of aircraft operation were addressed through comprehensive data analysis and interpretation. The measurement results were used to develop an inventory of aircraft emissions at BNE, including all modes of the aircraft LTO cycle and ground running procedures (GRP). Measurements of the actual duration of aircraft activity in each mode of operation (time-in-mode) and compiling a comprehensive matrix of gas and particle emission rates as a function of aircraft type and engine thrust level for real world situations was crucial for developing the inventory. The significance of the resulting matrix of emission rates in this study lies in the estimate it provides of the annual particle emissions due to aircraft operations, especially in terms of particle number. In summary, this PhD thesis presents for the first time a comprehensive study of the particle and NOx emission factors and rates along with the particle size distributions from aircraft operations and provides a basis for estimating such emissions at other airports. This is a significant addition to the scientific knowledge in terms of particle emissions from aircraft operations, since the standard particle number emissions rates are not currently available for aircraft activities.