|Résumé||(disponible en anglais seulement)|
A soil geochemical survey was undertaken in the maritime provinces of Canada. The survey was designed to reveal the variability of the near surface geochemistry
that is associated with underlying bedrock geology, effects of weathering, meteoric water infiltration, groundwater and anthropogenic activities. Soil samples collected from the O, A, B and C horizons from the Maritime Provinces of Canada were
analyzed using four-acid digestion and ICP-OES/MS instrumentation. An additional soil layer profile, PH (Public Health) of 0-5 cm depth was defined as part of the A horizon and is of interest in health risk assessments.
A principal component (PC)
analysis of the geochemistry from the four soil horizons reveals a distinctive set of inter-element relationships from the C horizon upwards into the B, A and PH horizons. Statistical dispersion of the soil geochemistry using a log-centred transform,
increases upwards in the profile. Maximum data dispersion occurs in the PH and A horizon soils. These trends are shown in Figure 1 where a bi-plot of the first two PC's accounts for 49.7% of the data variability. Elements including Cd, S, P, Pb, Bi,
Sb, Mo, Be, Zn and Cu are relatively enriched in the PH-A horizons (correlated with increasing organic carbon content) while elements including Ni, Mg, Cr, V, Co, Fe and Sc are relatively enriched in the C horizon, representing a mafic component of
the protolith. The felsic component of the protolith is expressed as a relative enrichment of K, Rb, Zr, (REE), Li and Al. This lithologic trend is exhibited along the second PC axis. The relative associations revealed in the bi-plot of Figure 1
enable the recognition of the underlying protolith, weathering, meteoric water and groundwater effects. The sources of these associations may be attributed to the underlying geology, anthropogenic activity, or a combination of both. The influence of
bedrock geology, climate and geomorphology (ecoregions) can be used to characterize the regional variability of the geochemistry for environmental and population health risk assessments. These same geochemical associations are also observed in other
areas of North America. Additional statistical analyses and maps will be shown.