Size Distributions of Water Soluble Ions in Atmospheric Aerosol at Lin’an Regional Background Station

摘要

To investigate regional characteristics of aerosol pollution in the area of Changjiang river delta in China, atmospheric aerosol samples were collected with Andersen cascade sampler at Lin’an regional background station during April, July, October of 2008 and January of 2009. The water soluble ionic concentrations were analyzed by IC. Results showed three different size distributions for the ions characterized, including masses in: (i) the accumulation mode, with a peak at 0.43 to 1.1 μm (SO 1 1 Zhejiang Institute of Meteorological Sciences, Hangzhou 310017, China 2 Zhejiang Meteorology Bureau, Hangzhou 310002, China ABSTRACT 4 2-, NH4 +, K+); (ii) the coarse particle mode, with a peak at 4.7 to 5.8μm (Ca2+, Mg2+); and (iii) a bimodal distribution, with peaks at 0.43 to 1.1 μm and 4.7 to 5.8 μm (NO3 -, Na+, Cl- ). The measured distributions are believed to result from a combination of processes including regional anthropogenic and natural sources, and long-range transport. The size distributions of the water soluble ions studied were influenced by at least three processes governing their concentrations in fine and coarse particles: (i) primary emissions of ultrafine particles from combustion and industrial processes; (ii) advection of air masses containing aged intermediate size aerosols; (iii) large particles arising mainly from re-suspension.