Disentangling artificial and natural benthic weathering in organic rich Baltic Sea sediments

• DOI: 10.3389/fclim.2023.1245580
• Publication Date: 2023-10-25T05:45:20Z
• Authors: Michael Fuhr; Klaus Wallmann; Andrew W. Dale; Isabel Diercks; Habeeb Thanveer K...; Mark Schmidt; Stefan Sommer; Stefanie Böhnke; Mirjam Perner; Sonja Geilert
• Keywords: Alkalinity; Biogeochemical Cycle

Enhanced mineral dissolution in the benthic environment is currently discussed as a potential technique for ocean alkalinity enhancement (OAE) to reduce atmospheric CO 2 levels. This study explores how biogeochemical processes affect of alkaline minerals surface sediments during laboratory incubation experiments. These involved introducing dunite and calcite organic-rich from Baltic Sea under controlled conditions an oxic environment. The sediment cores were incubated with bottom water. Findings reveal that addition increased release 0.4 μmol cm −2 d −1 (control) 1.4 (calcite) well other weathering products such calcium. However, these enhanced fluxes returned lower after approximately 4 weeks yet still higher than un-amended controls. Microbial activity appeared be primary driver lowering pore water pH thus weathering. In several cores, profiles taken at start experiments indicated sulfur oxidizing Beggiatoa spp, which was verified by RNA-profiling 16S rRNA genes. transitioned those commonly associated cable bacteria progressed. metabolic would explain significantly values (~5.6) depths 1–3 cm, favor substantial dissolution. high abundance not reflected sequence data. Total (TA) factor ~3, excess TA/calcium ratios indicating flux originated or formation secondary could identified due strong natural silicic acid, likely biogenic silica Furthermore, no accumulation potentially harmful metals nickel observed, highlighted risk studies concerning OAE. Given complexity chemistry changes induced incubation, it remains challenging distinguish between Further investigation, including identification suitable tracers dissolution, are necessary assess feasibility practical approach OAE climate change mitigation.