Benthic Organic Matter Transformation Drives pH and Carbonate Chemistry in Arctic Marine Sediments

Abstract

The Arctic Ocean, and in particular its seasonally ice-free areas, is highly vulnerable to ocean acidification (OA) due to its large carbon dioxide ( 𝐴𝐴 𝐴𝐴𝐴𝐴2) uptake capacity. It acts as a global hotspot of atmospheric 𝐴𝐴 𝐴𝐴𝐴𝐴2 drawdown due to its permanently cold surface waters, its undersaturation with respect to 𝐴𝐴 𝐴𝐴𝐴𝐴2 , and brine rejection during sea-ice formation that mixes surface 𝐴𝐴 𝐴𝐴𝐴𝐴2 into deeper water layers (Chen & Borges, 2009;Kaltin et al., 2002). Air-sea 𝐴𝐴 𝐴𝐴𝐴𝐴2 exchange exerts an important control on seawater pH and its carbonate saturation state (Ω) (Millero, 2000;Zeebe & Wolf-Gladrow, 2001). An increase in atmospheric 𝐴𝐴 𝐴𝐴𝐴𝐴2 level (e.g., by anthropogenic emissions) can induce negative shifts in pH and Ω (Bindoff et al., 2019;Friedlingstein et al., 2019), leading to OA (Doney et al., 2020; Gattuso & Hansson, 2011). In addition to air-sea 𝐴𝐴 𝐴𝐴𝐴𝐴2 fluxes, the carbonate chemistry of the Arctic Ocean is further modulated by the distribution of water masses with contrasting physico-chemical

Persistent increase in carbon burial in the Gulf of Mannar, during the Meghalayan Age: Influence of primary productivity and better preservation

“…The seawater pH at the sediment–water interface as well as of the pore water, also strongly modulates carbon burial (Keil, 2017; LaRowe et al 2020; Freitas et al 2022). As the core site lies in the oxygen-deficient zone, the pH at the sediment–water interface is likely to strongly modulate carbon burial in the sediments, before the remineralization of both the organic matter and CaCO 3 .…”

Benthic Organic Matter Transformation Drives pH and Carbonate Chemistry in Arctic Marine Sediments

“…The model employed here is based on . The updated model code with the implemented pH and carbonate dynamics is available at the Zonedo repository (Freitas, 2022; https://doi.org/10.5281/ zenodo.6384988).…”