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Polycyclic aromatic hydrocarbons (PAHs) have attracted an increasing concern in China's megacities. However, rare information is available on the spatial and seasonal variations of inhalation cancer risk (ICR) due to PAH exposure and their relations to specific sources. In this study, year-round PM 2.5 samples were collected from 2013 to 2014 by high-volume samplers at four sites (one urban, two rural and one roadside station) in Guangzhou in the highly industrialized and densely populated Pearl River Delta (PRD) region and analyzed for 26 polycyclic aromatic hydrocarbons (PAHs) together with molecular tracers including levoglucosan, hopanes and elemental carbon. Higher molecular weight PAHs (5-ring or above) accounted for 64.3–87.5% of total PAHs. Estimated annual averages of benzo( a )pyrene-equivalent carcinogenic potency (BaP eq ) were 1.37, 2.31 and 1.56 ng/m 3 at urban SZ, rural JL and rural WQS, respectively, much higher than that at the roadside station YJ in an urban street canyon. ICR of PAHs in wintertime reached 2.2 × 10 −4 , nearly 3 times that in summer; and cancer risk of PAHs was surprisingly higher at the rural site than at other sites. Source contributions by positive matrix factorization (PMF) in the aid of molecular tracers revealed that overall coal combustion and biomass burning altogether contributed 73.8% of total PAHs and 85.2% of BaP eq , and particularly in winter biomass burning became the most significant source of total PAHs and BaP eq (51.8% and 52.5%), followed by coal combustion (32.0% and 39.1%) and vehicle emission (16.2% and 8.4%). The findings of this work suggest that even in China's megacities like Guangzhou, limiting biomass burning may benefit PAHs pollution control and cancer risk reduction. [ABSTRACT FROM AUTHOR]

Pragmatic Chinese ideological slogans like "groping for stones crossing the river", "no matter if it's a black cat or a white cat, as long as it catches mice it's a good cat" became guiding principles for a multitude of experimental approaches to new developments in the realms of Chinese economic, political, socio-cultural, and physical urban transformation since the beginning of reform and opening up in the late 1970s. Today, these concepts find their daily expression in so-called conceded informality. This paper illuminates the characteristics of nowadays typical, Chinese decision- and policy-making processes in the field of urban restructuring, with a focus on the informal and experimental aspects of flexible conceptual frameworks. [ABSTRACT FROM AUTHOR]

This paper uses Guangzhou’s experience of hosting the 2010 Asian Games to illustrate Guangzhou’s engagement with scalar politics. This includes concurrent processes of intra-regional restructuring to position Guangzhou as a central city in south China and a ‘negotiated scale-jump’ to connect with the world under conditions negotiated in part with the overarching strong central state, testing the limit of Guangzhou’s geopolitical expansion. Guangzhou’s attempts were aided further by using the Asian Games as a vehicle for addressing condensed urban spatial restructuring to enhance its own production/accumulation capacities, and for facilitating urban redevelopment projects to achieve a ‘global’ appearance and exploit the city’s real estate development potential. Guangzhou’s experience of hosting the Games provides important lessons for expanding our understanding of how regional cities may pursue their development goals under the strong central state and how event-led development contributes to this. [ABSTRACT FROM PUBLISHER]

Abstract: Fine particulate samples were simultaneously collected at six sites in Guangzhou in November–December 2009. Eighteen polycyclic aromatic hydrocarbons (PAHs) and tracers, i.e. hopanes, elemental carbon, picene and levoglucosan were measured. Three high level episodes were observed during the sampling period, likely due to accumulation effects. Back trajectory analysis revealed that the air masses for the three episodes were from eastern inland Pearl River Delta (PRD) region. There was no obvious concentration gradient for total and 5–6 ring PAHs such as benzo[g,h,i]perylene (BghiP) from urban to rural sites. However, 4-ring PAHs such as pyrene (Pyr) exhibited significantly higher levels at rural site than that at urban/suburban sites (p <0.01). BghiP correlated well with hopanes, elemental carbon and picene, indicating vehicular emissions and coal combustion were the sources of 5–6 ring PAHs, which were further confirmed by comparing the four tracers/BghiP ratios and IcdP/BghiP ratios in ambient samples with those from source profiles. Results indicated that vehicular emissions were no longer the dominant sources in winter season in Guangzhou. [Copyright &y& Elsevier]

Guangzhou (GZ) is one of the highly industrialized and economically vibrant cities in China, yet it remains relatively understudied in terms of its air quality, which has become severely degraded. In this study, extensive air sampling campaigns had been conducted at GZ urban sites and in Dinghu Mountain (DM), a rural site, in the Pearl River Delta (PRD) during the spring of 2001 and 2005. Additionally, roadside and tunnel samples were collected in GZ in 2000 and 2005. Later, exhaust samples from liquefied petroleum gas (LPG)- and gasoline-fueled taxis were collected in 2006. All samples were analyzed for C2–C10 non-methane hydrocarbons (NMHCs). NMHC profiles showed significant differences in the exhaust samples between gasoline- and LPG-fueled taxis. Propane (47%) was the dominant hydrocarbon in the exhaust of the LPG-fueled taxis, while ethene (35%) was the dominant one in that of gasoline-fueled taxis. The use of LPG-fueled buses and taxis since 2003 and the leakage from these LPG-fueled vehicles were the major factors for the much higher level of propane in GZ urban area in 2005 compared to 2001. The mixing ratios of toluene, ethylbenzene, m/p-xylene and o-xylene decreased at the GZ and DM sites between 2001 and 2005, especially for toluene in GZ, despite the sharp increase in the number of registered motor vehicles in GZ. This phenomenon was driven in part by the closure of polluting industries as well as the upgrading of the road network in urban GZ and in part by the implementation of more stringent emission standards for polluting industries and motor vehicles in the PRD region. [Copyright &y& Elsevier]