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Hosseini Bai S.,Griffith University | Hosseini Bai S.,University of The Sunshine Coast | Sun F.,Shenzhen Academy of Environmental science | Xu Z.,Griffith University | Blumfield T.J.,Griffith University
Journal of Soils and Sediments | Year: 2013

Purpose: Understorey Acacia spp. plays an important role in post-fire restoration because these understorey plants are tolerant to stress conditions. We investigated how the ecophysiological status of two species of understorey, Acacia leiocalyx and Acacia disparrima, varied depending on the plant growth stage after prescribed burning. Materials and methods: Plants were grouped in different size classes, namely seedlings, small and medium sizes, and physiological variables such as foliar gas exchange, water use efficiency and light dependency were measured at two experimental sites subjected to prescribed burning. Results and discussion: A. leiocalyx showed higher symbiotic N2 fixation and photosynthetic capacity compared to A. disparrima regardless of plant-size classes at both experimental sites. This could explain the greater relative growth rate of A. leiocalyx than that of A. disparrima. However, A. disparrima is more tolerant to shady conditions than A. leiocalyx. Conclusions: This finding may be an indication of how well these two species recover after fire, although A. leiocalyx may have faster regrowth, as it is fixing more N. © 2013 Springer-Verlag Berlin Heidelberg. Source

Zhang J.P.,Peking University | Zhu T.,Peking University | Zhang Q.H.,Peking University | Li C.C.,Peking University | And 6 more authors.
Atmospheric Chemistry and Physics | Year: 2012

This study investigated the air pollution characteristics of synoptic-scale circulation in the Beijing megacity, and provided quantitative evaluation of the impacts of circulation patterns on air quality during the 2008 Beijing Summer Olympics. Nine weather circulation types (CTs) were objectively identified over the North China region during 2000-2009, using obliquely rotated T-mode principal component analysis (PCA). The resulting CTs were examined in relation to the local meteorology, regional transport pathways, and air quality parameters, respectively. The FLEXPART-WRF model was used to calculate 48-h backward plume trajectories for each CT. Each CT was characterized with distinct local meteorology and air mass origin. CT 1 (high pressure to the west with a strong pressure gradient) was characterized by a northwestern air mass origin, with the smallest local and southeasterly air mass sources, and CT 6 (high pressure to the northwest) had air mass sources mostly from the north and east. On the contrary, CTs 5, 8, and 9 (weak pressure field, high pressure to the east, and low pressure to the northwest, respectively) were characterized by southern and southeastern trajectories, which indicated a greater influence of high pollutant emission sources. In turn, poor air quality in Beijing (high loadings of PM 10, BC, SO 2, NO 2, NO x, O 3, AOD, and low visibility) was associated with these CTs. Good air quality in Beijing was associated with CTs 1 and 6. The average visibilities (with ±1α) in Beijing for CTs 1 and 6 during 2000-2009 were 18.5 ± 8.3 km and 14.3 ± 8.5 km, respectively. In contrast, low visibility values of 6.0 ± 3.5 km, 6.6 ± 3.7 km, and 6.7 ± 3.6 km were found in CTs 5, 8, and 9, respectively. The mean concentrations of PM10 for CTs 1, 6, 5, 8, and 9 during 2005-2009 were 90.3 ± 76.3 μg m -3, 111.7 ± 89.6 μg m -3, 173.4 ± 105.8 μg m -3, 158.4 ± 90.0 μg m -3, and 151.2 ± 93.1 μg m -3, respectively.

Analysis of the relationship between circulation pattern and air quality during the emission control period suggests that CTs are the primary drivers of day-to-day variations in pollutant concentrations over Beijing and its vicinity. During the Olympics period, the frequency of CT 6 was twice that of the mean in August from 2000 to 2009. This CT had northerly transport pathways and favorable meteorological conditions (e.g. frequent precipitation) for clean air during the Olympics. Assuming that relationships between CTs and air quality parameters in the same season are fixed in different years, the relative contributions of synoptic circulation to decreases in PM10, BC, SO2, NO2, NOx, CO, and horizontal light extinction during the Olympics were estimated as 19 ± 14%, 18 ± 13%, 41 ± 36%, 12 ± 7%, 10 ± 5%, 19 ± 11%, and 54 ± 25%, respectively. © 2012 Author(s). Source

Che X.,Shenzhen Academy of Environmental science | English A.,Victoria University | Lu J.,Shenzhen Urban Planning and Research Center | Chen Y.D.,Chinese University of Hong Kong
Environmental Impact Assessment Review | Year: 2011

The enactment and implementation of the 2003 EIA Law in China institutionalised the role of plan environmental impact assessment (PEIA). While the philosophy, methodology and mechanisms of PEIA have gradually permeated through the various levels of government with a positive effect on the process and outcome of urban planning, only a few cities in China have so far carried out PEIA as a Strategic Environmental Assessment (SEA)-type procedure. One such case is the southern city of Shenzhen. During the past three decades, Shenzhen has grown from a small town to a large and booming city as China has successfully and rapidly developed its economy by adopting the "reform and open door" policy. In response to the challenges arising from the generally divergent processes of rapid urbanisation, economic transformation and environment protection, Shenzhen has incrementally adopted the SEA concept in developing the city's Master Urban Plan. As such, this paper reviews the effectiveness of PEIA in three ways: •as a tool and process for achieving more sustainable and strategic planning;•to determine the level of integration of SEA within the planning system; and,•its effectiveness vis-à-vis implementation.The implementation of PEIA within Shenzhen's Master Urban Plan offers important insights into the emergence of innovative practices in undertaking PEIA as well as theoretical contributions to the field, especially in exploring the relationship between PEIA and SEA and highlighting the central role of local governing institutions in SEA development. © 2010 Elsevier Inc. Source

Liu Q.,Jinan University | Liu Q.,Shenzhen Academy of Environmental science | Hu X.,Jinan University | Hu X.,Chinese Academy of Fishery Sciences | And 4 more authors.
Journal of Geographical Sciences | Year: 2014

The water quality in the surface microlayer (SML) and subsurface water (SSW) in the Guangzhou segment of Pearl River, a eutrophic urban river section in China, were analyzed. The spatial and temporal dynamics of nutrient concentrations, heavy metals and bacteria were examined from two sampling sites in monthly samples throughout 2010. The mean concentrations of total nitrogen, ammonia, nitrate and nitrite were higher than 7.0 mg/L, 3.1 mg/L, 1.1 mg/L and 0.3 mg/L, while total phosphorus and orthophosphate were 0.5 mg/L and 0.1 mg/L, respectively. These results indicated that the water quality was rich in minerals and eutrophic. The mean concentrations of Mn and Fe were higher than 0.013 mg/L; and Ni, Cr and Pb were higher than 0.001 mg/L. The mean concentrations were in the order of Mn >Fe > Ni > Pb > Cr. The concentrations of heavy metals in the Guangzhou segment were lower than the limit of the surface water quality standards in China and the World Health Organization (WHO), but higher than the median values in the world's freshwater. The density of bacteria ranged from 3.30×105 to 5.23×106 cells/mL, and the amount of cultivable heterotrophic bacteria ranged from 1.30×103 to 1.89×106 cfu/mL. Fecal coliform levels were beyond the V class of China water quality standard. The SML was enriched in nutrients, heavy metals and bacteria, with the maximum enrichment factor of 3.84 for nutrients, 8.00 for heavy metals, and 3.04 for bacteria, suggesting that the water quality of the SML of the Guangzhou segment of the Pearl River was more serious than in the SSW. © 2014 Science Press and Springer-Verlag Berlin Heidelberg. Source

Zheng J.,South China University of Technology | Zheng J.,Pearl River Delta Atmospheric Environmental Research Joint Laboratory | Che W.,South China University of Technology | Che W.,Pearl River Delta Atmospheric Environmental Research Joint Laboratory | And 4 more authors.
Aerosol and Air Quality Research | Year: 2013

Characterizing spatial and temporal variations of PM pollution is critical for a thorough understanding of its formation, transport and accumulation in the atmosphere. In this study, Aerosol Optical Thickness (AOT) data retrieved from a Moderate Resolution Imaging Spectroradiometer (MODIS) were used to investigate the spatial and temporal variations of PM10 (particles with aerodynamic diameters of less than 10 μm) pollution in the Pearl River Delta (PRD) region. Seasonal linear regression models between 1-km retrieved MODIS AOT data and ground PM10 measurements were developed for the PRD region with meteorological corrections, and were subjected to a validation against observations from the regional air monitoring network in this region from 2006 to 2008, with an overall error of less than 50%. Consistent with ground observations, the estimated PM10 concentrations from the regression models appeared to be highest in winter, lower in autumn and spring, and lowest in summer. A high PM10 concentration band was detected over the inner part of the PRD region, where heavy industries and dense populations are located. The shape and concentration levels of this band exhibit significant seasonal variations, which shift with synoptic wind direction, indicating different source regions and their contributions to the PM10 pollution in the PRD region. Several discrete "hot spots" were found in the southwest of the PRD region during spring and other seasons, where no ground measurements are available. The reasons for the formation of these hot spots are unclear, and further investigations are needed. Despite the limitations of this work, the results demonstrate the effectiveness of retrieving remote sensing data for characterizing regional aerosol pollution, together with ground measurements. The combination of satellite data and ground monitoring presented in this work can help in better understanding the sources, formation mechanisms and transport process of particulate matters on a regional scale. © Taiwan Association for Aerosol Research. Source

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