The organic and inorganic species in total suspended particulates (TSP) collected from June to December in 1998 in Hong Kong were identified by gas chromatography-mass spectrometry (GC-MS) and inductively coupled plasma-mass spectrometry (ICP-MS) to investigate the sources of Hong Kong aerosols and the mechanisms that control the chemical compositions and variations in the atmosphere. These samples were classified according to the climate: wet, dry under the influence of southerly winds from the sea (Dry-S) and dry under the influence of northerly winds from the continent (Dry-N). There were significant increases of materials from crustal, biogenic and pollution sources in the Dry-N period by a factor of 5, 4, and 2, respectively. Since the crustal tracers (e.g., Al, Fe) could be from coal flyash, the estimate of crustal material in the Dry-N period may include some materials from pollution source. Therefore, a positive correlation between crustal and pollution elements was observed. From the analysis of solvent-extractable organics (SEOC), microbial and meat cooking sources showed slight increase (1.2-fold). Higher levels of plant wax materials in the Dry-N period were probably due to the higher wind speed during the winter monsoon. The percentage of crustal material in TSP was 47% in the Dry-N period, and only 22% in the wet season and the Dry-S period. Plant wax materials (biogenic source) had a higher percentage in the Dry-N period (39% of SEOC) while microbial and meat cooking sources accounted for 49% of SEOC in the wet season. This study revealed that wind direction and precipitation had a significant influence not only on the concentrations but also on the chemical compositions and sources of Hong Kong aerosols.
Lake areas in Chinese urban fringes are under increasing pressure of urbanization. Consequently, the conflict between rapid urban sprawl and the maintenance of water bodies in such areas urgently needs to be addressed. An integrated GIS-based analysis system (IGAS) for supporting land-use management of lake areas in urban fringes was developed in this paper. The IGAS consists of modules of land-use suitability assessment and change/demand analysis, and land evaluation and allocation. Multicriteria analysis and system dynamics techniques are used to assess land-use suitability and forecast potential land-use variation, respectively. Cost approximation and hypothetical development methods are used to evaluate land resource and market values, respectively. A case study implementing the system was performed on the Hanyang Lake area in the urban fringe of Wuhan City, central China, which is under significant urbanization pressure. Five categories of suitability were investigated by analyzing 11 criteria and related GIS data. Two scenarios for potential land-use changes from 2006 to 2020 were predicted, based on a systematic analysis and system dynamics modeling, and a hierarchical land-use structure was designed for the conservation of aquatic ecosystems. The IGAS may help local authorities better understand and address the complex land-use system, and develop improved land-use management strategies that better balance urban expansion and ecological conservation. (c) 2007 Elsevier B.V. All rights reserved.
Motor vehicle (MV) emissions and ambient particle concentrations under a variety of situations were studied in Toronto and Vancouver, Canada. Petroleum biomarkers (i.e., hopanes and steranes) were used to determine the fraction of fine particle organic carbon (OC) attributed to primary particles in MV exhaust. Source profiles obtained from a tunnel and from direct tailpipe emissions were applied to ambient measurements at locations ranging from rush hour traffic to a regional background site. The greatest amount of MV OC, 4.0 mu gC m(-3) out of 9.1 mu gC m(-3) or 43%, was observed 75 m south of a commuter highway during a period that included morning rush hour. Monthly estimates of MV-OC were determined for a downtown Toronto monitoring site for 2 years. Total OC concentrations were greater in the summer, due to secondary OC, but the amount of MV-OC did not exhibit a strong seasonal pattern. However, on a per cent basis, MV contributions from primary OC emissions were greatest in the winter (15-20%) and smallest in the summer (10-15%) with a two-year average of 14% of the OC or about 5% of the PM2.5. (c) 2006 Elsevier Ltd. All rights reserved.
Hong Kong's persistent unhealthy level of fine particulate matter is a current public health challenge, complicated by the city being located in the rapidly industrializing Pearl River Delta Region of China. While the sources of the region's fine particulate matter (PM2.5) are still not well understood, this study provides new source information through ground measurements and statistical analysis of 24 elements associated with particulate matter collected on filters. Field measurements took place over 4 months (October 2002, December 2002, March 2003, and June 2003) at seven sites throughout the Pearl River Delta, with three sites located in Hong Kong and four sites in the neighboring province, Guangdong. The 4-month average element concentrations show significant variation throughout the region, with higher levels of nearly every species seen among the northern Guangdong sites in comparison to Hong Kong. The high correlation (Pearson r>0.8) and similar magnitudes of 11 species (Al, Si, S, K, Ca, Mn, Fe, Zn, Br, Rb, and Pb) at three contrasting sites in Hong Kong indicate that sources external to Hong Kong dominate the regional levels of these elements. Further correlative analysis compared Hong Kong against potential source areas in Guangdong Province (Shenzhen, Zhongshan, and Guangzhou). Moderate correlation of sulfur for all pairings of Hong Kong sites with three Guangdong sites in developed areas (average Pearson r of 0.52–0.94) supports the importance of long-distance transport impacting the region as a whole, although local sources also clearly impact observed concentrations. Varying correlative characteristics for zinc when Hong Kong sites are paired with Shenzhen (average r=0.86), Guangzhou (average r=−0.65) and Zhongshan (average r=0.45) points to a source area located south of Guangzhou and locally impacting Zhongshan. The concentration distribution and correlative characteristics of bromide point to sources located within the Pearl River Delta, but the specific location is yet inconclusive. Uniquely poor correlation of eight species (Al, Si, K, Ca, Mn, Fe, Rb, and Pb) for the pairing of Hong Kong sites with Guangzhou, in addition to the relatively higher concentrations measured at Guangzhou, indicates a significant regional impact due to land development and industrial activities in the Guangzhou vicinity.