Browsing by Subject "svavelgasemission"

In recent years, research on the environmental impacts by acid sulfate soils have been in focus, but studies on sulfur gas emissions are relatively few. In contrast, emissions of SO2, H2S, COS, CS2 and (CH3)2S from different wetlands and other soils have been investigated more. Sulfur gases are difficult to study due to their high reactivity to environmental changes, regarding e.g. redox potential, temperature and water content. The aim of this thesis is to evaluate if sulfur gas analysis could be applied to the identification of acid sulfate soils, especially sulfidic materials. In autumn 2016, soil samples were taken from three agricultural fields in Ostrobothnia and Southern Ostrobothnia. The fields had been earlier classified as acid sulfate soils by the Geological Survey of Finland (GTK). The occurrence of sulfides in the soil material was identified based on the lowering of pH by aerobic incubation (10 weeks). In the laboratory, the sulfur gas emissions after a short incubation period were investigated with a gas chromatograph and a portable ChemPro100i gas detector (Environics Oy). The gas detector was additionally implemented directly in the field but the measurements were complicated by unfavorable weather conditions. Hydrogen sulfide (H2S) could not be identified in any soil sample and the occurrence of sulfur dioxide (SO2) was lower than expected. The unknown gas that was present in most samples and had the biggest peak areas is indirectly assumed to be carbonyl sulfide (COS). Based on the gas chromatographic analysis, the emissions of sulfur gases from soil samples were the larger, the larger was the pH-drop after the aerobic incubation. Five of the sensors (signals) in the gas detector showed a significant difference (p <0.05) in (sensor) resistance for sulfidic compared with non-sulfidic soil materials. Despite the promising results showing the potential of sulfur gas analysis to become a tool to aid the mapping of acid sulfate soils, more tests are needed, especially on the sulfur gas emissions from acid sulfate soils in the field during warm summer months.