The Pearl River Delta(PRD)is one of the three urban agglomerations in China that have experienced rapid development.For this study,a core area of the PRD was identified,comprising the highly urbanized areas of Guangzh...The Pearl River Delta(PRD)is one of the three urban agglomerations in China that have experienced rapid development.For this study,a core area of the PRD was identified,comprising the highly urbanized areas of Guangzhou,Foshan,Zhongshan,Zhuhai,Shenzhen,and Dongguan Cities.The expansion of these urban areas was tracked across three time periods—the year population urbanization rate exceeded 70%(2000),18 years before(1982),and 18 years after(2018).This study used the Weather Research and Forecasting(WRF)model to explore summer rainfall changes across different urbanization periods in the PRD core area.The results show that urban land expansion mainly occurred in the post urbanization period.Rainfall changes acros s different urbanization periods were roughly consistent with previously observed spatial and temporal changes accompanying urban expansion in the PRD core area.Extreme rainfall mainly increased in the post urbanization period,shifting rainstorm center towards the PRD core area.Further causal analysis revealed that land use changes affected rainfall by altering thermodynamics and water vapor transfer.The urban expansion changed the surface energy balance,resulting in increased surface heating and heat island effects.The heat island effects thickened the planetary boundary layer and increased vertical wind speeds,which initiated dry island effects,thereby causing more water vapor transportation to the atmosphere.Consequently,rainstorms and extreme rainfall events have become concentrated in urban areas.展开更多
Dongguan （东莞） City, located in the Pearl River Delta, South China, is famous for its rapid industrialization in the past 30 years. A total of 90 topsoil samples have been collected from agricultural fields, includ...Dongguan （东莞） City, located in the Pearl River Delta, South China, is famous for its rapid industrialization in the past 30 years. A total of 90 topsoil samples have been collected from agricultural fields, including vegetable and orchard soils in the city, and eight heavy metals （As, Cu, Cd, Cr, Hg, Ni, Pb, and Zn） and other items （pH values and organic matter） have been analyzed, to evaluate the influence of anthropic activities on the environmental quality of agricultural soils and to identify the spatial distribution of trace elements and possible sources of trace elements. The elements Hg, Pb, and Cd have accumulated remarkably here, incomparison with the soil background content of elements in Guangdong （广东） Province. Pollution is more serious in the western plain and the central region, which are heavily distributed with industries and rivers. Multivariate and geostatistical methods have been applied to differentiate the influences of natural processes and human activities on the pollution of heavy metals in topsoils in the study area. The results of cluster analysis （CA） and factor analysis （FA） show that Ni, Cr, Cu, Zn, and As are grouped in factor F1, Pb in F2, and Cd and Hg in F3, respectively. The spatial pattern of the three factors may be well demonstrated by geostatistical analysis. It is shown that the first factor could be considered as a natural source controlled by parent rocks. The second factor could be referred to as ＂industrial and traffic pollution sources＂. The source of the third factor is mainly controlled by long-term anthropic activities, as a consequence of agricultural activities, fossil fuel consumption, and atmospheric deposition.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52279015)。
文摘The Pearl River Delta(PRD)is one of the three urban agglomerations in China that have experienced rapid development.For this study,a core area of the PRD was identified,comprising the highly urbanized areas of Guangzhou,Foshan,Zhongshan,Zhuhai,Shenzhen,and Dongguan Cities.The expansion of these urban areas was tracked across three time periods—the year population urbanization rate exceeded 70%(2000),18 years before(1982),and 18 years after(2018).This study used the Weather Research and Forecasting(WRF)model to explore summer rainfall changes across different urbanization periods in the PRD core area.The results show that urban land expansion mainly occurred in the post urbanization period.Rainfall changes acros s different urbanization periods were roughly consistent with previously observed spatial and temporal changes accompanying urban expansion in the PRD core area.Extreme rainfall mainly increased in the post urbanization period,shifting rainstorm center towards the PRD core area.Further causal analysis revealed that land use changes affected rainfall by altering thermodynamics and water vapor transfer.The urban expansion changed the surface energy balance,resulting in increased surface heating and heat island effects.The heat island effects thickened the planetary boundary layer and increased vertical wind speeds,which initiated dry island effects,thereby causing more water vapor transportation to the atmosphere.Consequently,rainstorms and extreme rainfall events have become concentrated in urban areas.
基金supported by the Ministry of Land and Resources of China (No. [2005]011-16)State Environment Protection Administration of China (No. 2001-1-2)+2 种基金State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciencesthe Guangdong Provincial Office of SciencesTechnology via NSF Team Project and Key Project (Nos. 06202438, 2004A3030800)
文摘Dongguan （东莞） City, located in the Pearl River Delta, South China, is famous for its rapid industrialization in the past 30 years. A total of 90 topsoil samples have been collected from agricultural fields, including vegetable and orchard soils in the city, and eight heavy metals （As, Cu, Cd, Cr, Hg, Ni, Pb, and Zn） and other items （pH values and organic matter） have been analyzed, to evaluate the influence of anthropic activities on the environmental quality of agricultural soils and to identify the spatial distribution of trace elements and possible sources of trace elements. The elements Hg, Pb, and Cd have accumulated remarkably here, incomparison with the soil background content of elements in Guangdong （广东） Province. Pollution is more serious in the western plain and the central region, which are heavily distributed with industries and rivers. Multivariate and geostatistical methods have been applied to differentiate the influences of natural processes and human activities on the pollution of heavy metals in topsoils in the study area. The results of cluster analysis （CA） and factor analysis （FA） show that Ni, Cr, Cu, Zn, and As are grouped in factor F1, Pb in F2, and Cd and Hg in F3, respectively. The spatial pattern of the three factors may be well demonstrated by geostatistical analysis. It is shown that the first factor could be considered as a natural source controlled by parent rocks. The second factor could be referred to as ＂industrial and traffic pollution sources＂. The source of the third factor is mainly controlled by long-term anthropic activities, as a consequence of agricultural activities, fossil fuel consumption, and atmospheric deposition.
