Regional Eco-geochemical Assessment In Beijing And Guangzhou Urban Areas

“Regional Eco-geochemical Assessment in Beijing and Guangzhou Urban Areas” conducted a comprehensive research in two mega cities Guangzhou and Beijing, as the representative of the north and the south cities in China. The results showed that the soil heavy metal contents in city center areas were significantly higher than that analysed in peripheral areas of Beijing and Guangzhou, and mercury is the most significant element. The thermal-release mercury analysis showed that Hg Cl2 and Hg S were the most common ingredients of soil mercury in both cities. The analysis of characteristics of elements combination showed that the main source of dry and wet atmospheric deposition of Guangzhou was the smoke and dust emitted from metallurgical industry, while in Beijing the source was a mixture of coal combustion and metallurgical industry.The daily variation of mercury fluxes between soil/air interfaces was obvious in all monitoring points in both Beijing and Guangzhou. The mercury fluxes showed correlation with soil properties and meteorological factors, and vegetation condition significantly affected the emission of mercury from soil. The statistics results showed that soil gaseous Hg was an important sources of atmospheric Hg.Soil environmental quality assessment showed that Hg and Cd were the most prominent harmful heavy metal elements to soil ecology in the study areas. The environmental quality assessment of atmospheric particulate matter showed that air pollution was serious in both Guangzhou and Beijing, which reflected the urban atmospheric environment problem in China. Risk assessment of heavy metal showed that the risk was small in both cities, heavy metal wound not lead to significant health hazard to the city residents.The assessment of urban ecological system showed that the risk of city ecological in Guangzhou is higher than that of Beijing. The spatio-temporal evolution of the surface soil Hg trend prediction show that in 2060 the soil quality would fully recover in the centre of Beijing if the soil Hg content reduce at the current rate. The heavy metal content input- output analysis showed that Beijing urban soil was the source of Hg, and the sink of As, Cd and Pb, Guangzhou urban soil was the source of Cd, Hg and Pb, and the sink of As.