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A multiple till sequence interbedded with sorted sediments has been investigated at Vuosaari, Helsinki, Finland. The investigation was carried out using standard sedimentological procedures combined with microfossil analysis in order to determine the genesis of the exposed sediments. This evidence is used to correlate lithostratigraphically the sequence with adjacent multiple till sequences in other parts of southern Finland (south of the Salpausselkä zone).It is concluded that all three till beds at Vuosaari are of basal origin that were laid down by separate ice flow phases. In contrast two rhythmite beds between the tills are thought to have been deposited in open water. The sediments at Vuosaari may have been laid down during the Weichselian glaciation although it is also possible that the lowermost till bed represents Saalian till.

A multiple till succession at Koivusaarenneva in Central Ostrobothnia, adjacent to the Gulf of Bothnia, was studied using conventional sedimentological techniques. In addition, a sand-rich unit between two till beds was dated by the Optical Stimulated Luminescence (OSL) method and organic-bearing silt was subjected to pollen analysis. The methods were applied to determine the Pleistocene sedimentation history of the area. The results obtained indicate that the lowest till above the crystalline bedrock at Koivusaarenneva was deposited from the NNW during the Saalian glaciation, whereas the organic-bearing sediments and deformed sand and silt above, were laid down during the Eemian and the Early Weichselian stages. Two till beds above the Early Weichselian sediments indicate that at least two separate Scandinavian Ice Sheet advances took place in the area, most likely in the early Middle Weichselian and the Late Weichselian substages.

The occurrence and rates of terminal electron acceptor processes, and recharge processes in the unsaturated zone of a boreal site contaminated with petroleum hydrocarbons in the range C(10) to C(40) were examined. Soil microcosms were used to determine the rates of denitrification, iron (Fe) reduction, sulfate (SO(4)) reduction, and methanogenesis in two vertical soil profiles contaminated with oil, and in a noncontaminated reference sample. Furthermore, the abundances of the 16S rRNA genes belonging to Geobacteracaea in the samples were determined by real-time quantitative polymerase chain reaction (PCR). Analyses of ground water chemistry and soil gas composition were also performed together with continuous in situ monitoring of soil water and ground water chemistry. Several lines of evidence were obtained to demonstrate that both Fe reduction and methanogenesis played significant roles in the vertical profiles: Fe reduction rates up to 3.7 nmol h(-1) g(-1) were recorded and they correlated with the abundances of the Geobacteracaea 16S rRNA genes (range: 2.3 x 10(5) to 4.9 x 10(7) copies g(-1)). In the ground water, ferrous iron (Fe(2+)) concentration up to 55 mg L(-1) was measured. Methane production rates up to 2.5 nmol h(-1) g(-1) were obtained together with methane content up to 15% (vol/vol) in the soil gas. The continuous monitoring of soil water and ground water chemistry, microcosm experiments, and soil gas monitoring together demonstrated that the high microbial activity in the unsaturated zone resulted in rapid removal of oxygen from the infiltrating recharge thus leaving the anaerobic microbial processes dominant below 1.5 m depth both in the unsaturated and the saturated zones of the subsurface.

An area of permanent snow and frozen ground was studied at the end of summer seasons during the years 1990-1993 near the summit of Ridnitv sohkka fell, which at 1317 m a.s.l. is the second highest peak in Finland. The eastern flank of Ridnitv sohkka has the most extensive area of permanent snow (3 km 2) in Finland, while the summit region represents the highest single area of basal till devoid of vegetation cover and displaying patterned ground features. The ground penetrating radar results show that the form of the snowfield does not conform to the topography of the underlying bedrock and reveal the presence of several continuous reflectors dipping down-slope. Observations based on drilling and a single test pit indicate that the snowfield is 6.2 m thick and that it contains discontinuous lenses or layers of ice from 2 to 30 mm in thickness. Plant material from the depth of 4.05 m in the drilling core yielded a radiocarbon age of 35 years, while variations in the size of lichens growing at the edge of the snowfield indicated that the snowfield was of considerably greater extent some 100 to 150 years ago. The results suggest that the snowfield has been stable for a relatively long period but the "residence time" of snow in the snowfield is rather short, presumably less than 100 years and possibly only a few decades. Percussion drilling on the Ridnitv sohkka summit plateau, situating 1290 m a.s.l., revealed that the till was frozen at the depth of 1.9 m at the end of July 1993. Discovery of frozen till shows that frozen ground can locally survive from one season to the next, while the extent of the permanent snowfield and vegetationfree patterned ground suggest that the conditions favourable for permafrost might have existed over wider areas.

The chemical characterization of contaminated soil was assessed in two study areas in Finland contaminated with metals. The aqua regia extractable and/or concentrated nitric acid leachable median concentrations of selected elements within the study areas were first compared to those from various geochemical baseline studies. Based on this comparison, the studied elements were divided into two groups: elements displaying general enrichment in the study areas and those with median concentrations within the range of baseline levels. In addition to comparison with the baseline levels, the distribution of aqua regia extractable concentrations of selected elements was assessed in relation to the Finnish soil screening values. The potential leachability of the selected metallic elements in contaminated, mainly man-made soil was examined by determining the ratio between the median ammonium acetate and median aqua regia extractable concentrations in the two study areas. Aqua regia extractable concentrations are considered to represent the near-total fraction of the elements and ammonium acetate extractable concentrations the 'bioavailable' fraction. These ratios were compared with those from non-polluted sites representing geochemical baselines. In addition, water soluble element concentrations were available from the two study areas and the ratio between synthetic rainwater or distilled, de-ionised water extractable and aqua regia extractable concentrations was calculated. The ratio between ammonium acetate extraction and aqua regia extraction indicated that of the studied elements, Cu, Ni, Pb, Zn and V exist in a more leachable form in contaminated soil than in the natural environment. It can be assumed that these elements are also more 'bioavailable' in contaminated land and could therefore pose a risk to the environment. The water soluble fraction of the potential harmful elements was generally low in both study areas, but single samples had easily leachable metal concentrations. High concentrations of trace elements were found in the groundwater on the down stream side of the potential pollution source. The chemical characteristics of the soil material in both study areas were defined with hierarchical cluster analysis, with the results presented as dendrograms produced using Ward's method. Although some clusters were identified from the dendrograms, no special characterization of the fill material was possible. However, suggestive grouping of certain element groups was observed. Similar grouping of elements was found in factor analysis. Cluster analysis as well as factor analysis was found to be feasible for the chemical characterization of soil provided that a sufficient number of samples with appropriate analysis are available.

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