Unraveling ocean pCO 2 dynamics in Northwest Greenland Fjords

We investigated the relative contributions of various factors that influence seasonal changes in sea surface partial pressure of ${\text{CO}}_2$ ( ${\text{pCO}}_2$ , calculated from the measured pH and total alkalinity) in four regions of northwestern Greenland: Nares Strait, Lincoln Sea, Sherard Osborn and Petermann fjords. Using the temperature minimum layer as a proxy for winter conditions, we examined ${\text{pCO}}_2$ dynamics from the onset of sea-ice melt to summer. Our findings revealed significant spatial variability in ${\text{pCO}}_2$ , driven by differences in temperature, freshwater inputs, and biological activity. In particular, in Sherard Osborn Fjord substantial freshwater inputs and strong stratification were found to enhance ${\text{pCO}}_2$ accumulation, while in Petermann Fjord biological ${\text{CO}}_2$ uptake was the main driver. This study, conducted in summer 2019, underscores the critical role of northwest Greenland's coastal waters as a summer ${\text{CO}}_2$ sink. It highlights the complex interplay of physical and biogeochemical processes in modulating ${\text{pCO}}_2$ , suggesting significant regional differences in ${\text{CO}}_2$ dynamics between two neighboring fjords.