Bachelor Thesis

Spatial distribution of metal(loid)s around a mofette

Lukas Gerber (03/2017-05/2018)

Support: Britta Planer-Friedrich, Judith Forberg

Within the context of the prevalent Carbon Capture and Storage (CCS) process for reducing CO2 emissions, risk assessments are essential in order to evaluate and identify risks for soil and drinking water; it is useful to analyze changes in mofette soils as an analogue. The origin of mofettes is volcanic or tectonic activity. CO2 bubbles-up from the earth’s mantle through the soil where it reaches the atmosphere. Throughout this project, soil and porewater samples were taken and analyzed by ICP-MS and photometry. The frequently handled study site was close to the village Franzensbad in close proximity to the river Plesná. Relocation patterns of metal(loid)s were observed from the measuring-grid, which was used. An accumulation of sulphur, copper and zinc was observed in the depth of the anoxic mofette centre. There was also an accu-mulation of organic matter (Beulig et al. 2015), which is used as a binding partner of the metal(loid)s (Mehlhorn et al. 2014). Although the high concentrations of sulphur, copper, and zinc indicate the formation of sulfides in the highly anoxic soil. A shift of Iron, arsenic, and manganese to the oxic area outside the mofette was detected. There might be formations of iron-oxides, iron-hydroxides, manganese-oxides, and maganese-hydroxides which are hindered to an extent in the anoxic centre (Rennert et al. 2011). Heavy metals are able to bind to these oxides. Due to the mobilisation and immobilisation of metal(loid)s risks for agriculture and drinking water quality can arise – these are to be considered by the CCS-procedure.