Bachelor Thesis

Potential Metal(loid)Mobilisation in two Tuscan wetlands under the influence of future sea level rise

Lukas Hald (11/2023-05/2024)

Support: Philipp Knobloch, Britta Planer-Friedrich

The two sampling sites are located in the southwest of Tuscany, in the northernmost area of the Tyrrhenian Sea, near the coast, each surrounded by two channels or river courses. Both areas are situated in a contaminated river system where the action threshold for arsenic is exceeded. With the predicted rise in sea level, these areas will be regularly or completely flooded with sea or brackish water in the future (in 60 and 100 years). The two locations were chosen to assess possible climate scenarios and their impact on the mobilization of arsenic, as well as the current mobility away from a hematite or pyrite waste dump (Scarlino) and from the sea (Diaccia-Botrona). To evaluate the risk of arsenic (and other (semi- )metals) mobilization under future climate scenarios, samples were taken at both sites below the surface (about 20 cm deep). The samples were flooded with seawater under various short-term and long-term experiments. The results show that the threshold values for various (semi-)metals could be exceeded, with Ni, As, Cd, Sb, and Pb aerobically and Al, Mn, Fe, Ni, As, Se, Sb, and U anaerobically. It is evident that the salt concentration of the river or the sea is decisive in this area. Thus, areas that are currently more exposed to the river system may mobilize more arsenic in the future.