| Summary: | Globally rising anthropogenic CO₂ emissions have resulted in the increased prevalence of ocean acidification (OA) which has the potential to impact shell-forming organisms. On geologic timescales, the largest contributor to atmospheric CO₂ was volcanoes, counterbalanced by weathering and erosion, but due to increased anthropogenic emissions, these processes alone can no longer keep up with the demand. Mitigation strategies, such as ocean alkalinization enhancement (OAE), are being explored due to the increasing prevalence of OA and its relation to economic loss for commercially important aquaculture species. To see increased benefits for bivalves, shelly habitats, and OA we propose conducting OAE experiments on a smaller scale within estuarine habitats by amending sediments in highly metabolic systems. The goal of our experiments is to enhance what would be naturally occurring on geologic timescales, by returning ground minerals/biominerals to estuarine sediment cores to locally enhance alkalinity from mineral and biomineral dissolution. To narrow the scope for two sediment core amendment studies we conducted a mineral dissolution experiment. We measured the dissolution rates of minimally processed ground minerals and biominerals to understand how dissolution might change across various saturation states (Ω). Additionally, we measured overlying water alkalinity fluxes in non-homogenized and homogenized cores to better understand the potential alkalinity generation of amended sediment and the effects of mineral addition amount, respectively. Generally, dissolution rates increased with decreasing saturation state and grain size. Mineral dissolution rates found the highest dissolution rates in biominerals and relatively slow rates with olivine. Our non-homogenized core amendment experimental results yielded high variation in alkalinity flux measurements but found a ~20% increase in alkalinity fluxes in cores amended with calcite and bio-calcite. However, the follow-up core amendment experiment, in which we ...
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