Seasonal variations in hydrogen deposition to boreal forest soil in southern Finland

In this study deposition velocity ( v d ) of atmospheric hydrogen to mineral and peat soils was measured in boreal forest environments in southern Finland using soil chamber measurement technique. v d was largest during the snow‐free season (0.04–0.07 cm/s) and smallest during winter (0–0.04 cm/s). Velocities decreased when soil temperature fell below 5°C, but deposition was observed also in near‐zero temperatures. Deposition velocities to organic soil forest floor were larger than to mineral soil, but it was unclear whether this was due to the effect of carbon or the effect on soil porosity. Fluxes to both mineral and peat soils had similar temperature and soil moisture responses. In very dry and moist conditions v d decreased rapidly. Optimum soil moisture ranged from about 6 to 50 % of water by volume. The magnitude of v d was similar at urban Helsinki and at rural Loppi sites.