A mechanism for the increase of pollution elements in dust storms in Beijing

It is well known that springtime dust storms in northern China are created by strong winds associated with cold fronts. One unexpected aspect of the dust, observed recently, is that it contains high concentrations of pollution elements. It is believed that dust particles were mixed well with pollution substances during the transport, thus the pollution elements are thought to be pollution derived. A careful examination of concentrations of elements, pollution gases, and meteorology during March 2001 and March 2002 in Beijing showed that the dust itself was an important source for some pollution elements. A more important by-product was the finding that dust storms in Beijing typically contain four stages: (1) accumulation of pollutants in the atmosphere of Beijing; (2) clear-out of pollutants; (3) addition of pure dust; and (4) clear-out of the dust. The pure dust can appear before the accumulated pollutants are cleared out, which mixes the two and makes it appear that the pollutants came from it. Pollution gases and PM10 also reveal the same four stages. When PM10 varies inversely with the pollution gases, as it does during dust storms in Beijing and occasionally in Shanghai, it includes transported dust. This pattern makes it possible to study dust storms by examining the longer records of pollution gases and PM10 that are now being generated by municipal environmental bureaus throughout China. (C) 2003 Elsevier Ltd. All rights reserved.