Instrumental neutron activation analysis (INAA) and inductively coupled plasma/mass spectrometry (ICP-MS) for trace element biomonitoring using mosses

Two analytical methods - instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS) - were used for the trace element analysis of naturally growing mosses for a heavy metal biomonitoring survey. The techniques were applied to reference mosses to evaluate the feasibility, analytical variability, detection limits and accuracy. These parameters were evaluated using 563 mosses sampled in the 1996 French survey. All the elements of interest in the European program "Atmospheric Heavy Metal Deposition in Europe - estimation based on moss analysis" (As, Cd, Cr, Cu, Fe, Hg, Pb, Ni, V, Zn) were able to be determined by ICP-MS. INAA appeared suitable for the determination of As, Cr, Fe, Hg, V and Zn. The Cd, Cu, Ni and Pb concentrations determined by ICP-MS were preferred to the INAA results, because of increased feasibility or accuracy. The results provided by both methods on the French mosses were statistically compared for 14 elements. Significant linear correlation appeared for: Ba, Ce, Cs, La, Rb, Sm, Th and V. Among these eight elements, Ba, Cs, La and Sm concentrations determined by both methods exhibited a strong statistical similarity. The correlations obtained for As, Eu, Fe and Sb were not as strong and no correlation at all was observed for Co and Cr. These differences were attributed to instrumental factors (e.g. spectral interference occurred for both methods) or due to the sample preparation prior to ICP-MS. The consequences of such results on the regional trend evaluation of atmospheric heavy metal deposition were discussed.