ABSTRACT
To study the concentration characteristics as well as sources of elements and heavy metal pollution in atmospheric dust fall in Zhuzhou City, 144 samples from 12 sites in the Zhuzhou urban area were collected from January to December in 2012 and 28 kinds of elements in the samples were analyzed. The results showed that the dust fall quantities of the industrial areas and mixed commercial and residential (MCR) areas were, respectively, 89.46 g·m-2 and 33.20 g·m-2 and the range of all sample points was 23.14-114.67 g·m-2. There were 10 elements (Na, Mg, Al, K, Ca, Ti, Mn, Fe, Zn, Pb) in the industrial areas as well as 8 elements in the MCR areas, for which the contents greatly exceeded 1000 mg·m-1 in the atmospheric dust fall. The Zn and Pb contents exceeded 10000 mg·kg-1 in the dust fall of the industrial areas, which were far higher than those in the Earth's crust. The main sources of dust fall in Zhuzhou City were metal smelting, shallow ground dust, vehicle emissions, construction dust, and industrial production with specific elements (Mo, Ba). Correlation analysis, principal component analysis (PCA), and analysis of transportation characteristics showed that 13 elements (Mn, Fe, Co, Cu, Zn, As, Se, Ag, Cd, Sn, Sb, Tl, Pb) in dust fall mainly came from waste gas emissions of industrial areas in Zhuzhou, in which 7 heavy metal elements (Cu, Zn, As, Ag, Cd, Sb, Pb) caused serious pollution. The contents of heavy metals in the industrial areas were 7.4 to 4079.4 times the contents defined in China soil elements background values, whereas those in the MCR areas were 3.6 to 1413.4 times the soil background values. Cd was the highest background ratio element. The degree of contamination was clearly higher in the industrial areas than in the MCR areas.
ABSTRACT
Atmospheric particle number concentrations were measured from September 2010 to August 2011 with potable light house laser particle counter to study the variation of atmospheric particle concentrations and its impact on visibility in Qingdao. Backward trajectory was calculated by Hysplit model. Statistical analysis was done to discuss the influence of meteorological factors on the atmospheric particle number concentrations and visibility. It was shown that the atmospheric particle number concentrations were the highest in winter and spring, followed by autumn, and the lowest in summer. Air mass from Xinjiang and Gansu regions resulted in higher particle concentrations, while the atmospheric particles from the northeast and the ocean had lower concentrations. The variation of atmospheric particle number concentrations presented a good negative correlation with the variation of wind speed, relative humidity and mixed-layer height. When the air mass came from west or northwest, the surface wind direction was south or southeast and the mixed-layer height was low, the number concentration of fine particles was likely to be higher, which tended to cause low visibility phenomenon.
