“…In some cases, such as those studies in the Antarctic and Greenland, filtering is simply not possible due to the extremely low abundance of elements, and it is therefore assumed that any particulate matter is incorporated during analysis. This seems a reasonable assumption for more recent analytical methods such as laser-excited atomic fluorescence spectrometry (Bolshov and Boutron, 1994;Bolshov et al, 1997) or sector-ICP-MS ( Barbante et al, 1997;Townsend and Edwards, 1998). However, for studies of snowpack in areas that are not permanently snow-covered and those that receive large amounts of pollution, particulates are the dominant source of the chemical load for many elements and especially for many trace elements (Table 1 this paper; Gregurek et al, 1999a;Gregurek et al, 1999b;Caritat et al, 1998;Reimann, 1998;Gregurek et al, 1998;Reimann et al, 1996).…”