4.7. Sampling and analysis of TSP filters for the homogeneity study (VI)

The homogeneity study is part of an air sampling program carried out in 2000 at AvestaPolarit Chrome Oy Kemi Mine (see paper IV). The TSP filters for the homogeneity study were collected in January, March, May, July, September and November at monitoring station MA2 (Konttori). A total of 6 filters were collected for the homogeneity study.

In order to test the homogeneity of heavy metal deposition on the glass fibre filter (Munktell MG 160, 203*254 mm, 75 g/m², Grycksbo, Sweden), 9 discs (35 mm) were cut from different parts (1–9) of each filter (A–F) (see Paper VI, Fig. 1). The discs were then digested in a microwave oven using a mixture of aqua regia (i.e. conc. HNO₃ and conc. HCl; 1:3) + HF acid according to the procedure of Bettinelli et al. (90), who reported good recoveries for Cr in samples containing chromite, i.e. NBS SRM 278 Obsidian Rock, NBS SRM 688 Basalt Rock, NBS SRM 1645 River Sediment and NBS SRM 1646 Marine Sediment. The heavy metals (Cr, Ni, Cu, Fe and Cd) in the total suspended particulate (TSP) material were analysed by ICP-AES or GFAAS.