The 2023 EMU Medallist Lecture will be given by Jakub Kierczak 5th December 2023, 11.00-12.00 GMT. Ultramafic geosystems as a source of metallic elements to the environment Ultramafic rocks and associated soils are especially enriched in Ni, Cr, and Co. Strict legislative limits are established for maximum allowable concentrations of these metals in soils. However, ultramafic soils are a natural phenomenon where increased metal content is not the result of pollution, but rather referred to as a peculiar geochemical background, therefore there is no reason for their remediation. At the same time, it is not easy to find ultramafic soil that does not overstep the limits. The presentation will not only focus on the total metal content of ultramafic rocks and soils. The mobility and bioavailability of these metals will also be addressed. Since ultramafic substrates can vary in mineral composition the main focus of the presentation will be to answer whether the type of ultramafic rock affects the bioaccessibility of metals in ultramafic soils. In addition, the presentation will also address questions related to the fate of metallic elements during carbonation of ultramafic rocks. Register here (https://zoom.us/meeting/register/tJ0tc-iqqz8sE9SnlVT2brZEa1hwCN9Ab6p1) to join the webinar. There is no charge.