Based on results from the regional geochemical survey, a suite of 40 samples in two transects extending away from the smelter stack, 15 samples from two detailed soil profiles and 4 background samples were subjected to detailed analysis, including organic content determination and mineral composition, sequential extraction techniques, and SEM examination. The forms of the various elements in both humus and till were examined as a basis for assessing metal mobility and outlining criteria for the recognition of smelter-related contamination in the terrestrial environment. Results show that in humus, Zn in primarily associated with labile phases; Hg with non-labile phases. Adjacent to the smelter, high proportions and concentrations of Zn and Hg in non-labile phases, indicative of smelter particulates, are confirmed by SEM examination. The particles occur as spheres, irregular grains, and associated with organic matter. At highly contaminated sites (<3 km), in till, increased percentages of smelter related elements in labile phases may suggests heavy metals are leached from humus to the underlying sediments.

Detailed humus profile and forest litter samples were collected at 9 selected sites over the Flin Flon area to evaluate the relative significance of the regional database. In situ bulk density, moisture content and total metal concentration measurements in humus profiles and in the litter layer, combined with the regional dataset, permitted to assess factors influencing metal distribution within the organic horizon. These results have also been used to compare the amount of metals in the humus anomaly with the historical smelter emissions and to estimate the relative importance of short-range versus long-range atmospheric transport.

Photos of smelter related particles

SEM secondary image of heavy metal rich particle collected in humus, 2 km SSW of smelter stack.

SEM secondary image of hollow glassy sphere (Si, Al, O) collected in humus, 82 km NNW of smelter stack.