Unraveling ocean $$\hbox {pCO}_{2}$$ dynamics in Northwest Greenland Fjords

We investigated the relative contributions of various factors that influence seasonal changes in sea surface partial pressure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>pCO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> , 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>pCO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> dynamics from the onset of sea-ice melt to summer. Our findings revealed significant spatial variability in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>pCO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> , 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>pCO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> accumulation, while in Petermann Fjord biological <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> uptake was the main driver. This study, conducted in summer 2019, underscores the critical role of northwest Greenland's coastal waters as a summer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> sink. It highlights the complex interplay of physical and biogeochemical processes in modulating <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>pCO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> , suggesting significant regional differences in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CO</mml:mtext> <mml:mn>2</mml:mn></mml:msub> </mml:math> dynamics between two neighboring fjords.