Enhanced Weathering of Basalt: Effects of Fungal Inoculation, Citric Acid and Carbonation | Förstärkt vittring av basalt: effekterna av inokulering av svamp, citronsyra och kolsyrning

Anthropogenic greenhouse gas emissions are driving global warming, leading to planetary impacts suchas sea level rise, ecosystem collapse and extreme weather events. To mitigate these risks, IPCC hasstated that strategies like carbon dioxide (CO2) removal are needed alongside emission mitigation. Onesuch method is enhanced silicate weathering, which accelerates the natural CO2 drawdown from silicateweathering. This project examines three potential ways of increasing silicate (basalt) weathering. Three factorsare tested: 1. Biological enhancement (fungal inoculation with Talaromyces rugulosus), 2. carbonation(bubbling of CO2), and 3. acidification (using citric acid). Through 48 flow-through reactors, eachcontaining 100g of basalt, these factors were tested in various combinations to evaluate their effect onbasalt weathering. The reactors were irrigated with citric acid of different concentrations twice weeklyover seven weeks with 100 mL of the respective irrigation solution. After each irrigation event, theleachate was collected for analysis. The following geochemical analyses were conducted on the leachate:pH, electrical conductivity, dissolved carbon species, and cation analysis. After the experiment, the solidmaterial from all reactors was analysed using Raman spectroscopy, Scanning Electron Microscope andBrunauer-Emmett-Teller (B.E.T) analysis. The results showed that citric acid was the dominant factor influencing weathering. Its acidic nature,complexation, and chelating mechanisms strongly increased mineral dissolution, as observed throughan increase in cation release and specific surface area. The increase was proportional to increasing citricacid concentrations. A trend for irrigation frequency and weathering was also observed. Longer intervalsbetween irrigation led to increased pH and electrical conductivity, suggesting more weathering. Foreither fungal inoculation or carbonation, no clear trends indicating an effect on weathering could beobserved, at least not in comparison to the pronounced impact of citric acid.