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Subpolar coastal waters are key hotspots in the global carbon cycle. However, the small-scale distribution of partial pressure of carbon dioxide (p CO 2) in these environments and the physical and biological controls underlying this variability are still poorly understood. Here, we examine simultaneous high-resolution spatial measurements of wind speed and p CO 2 , temperature, salinity, and in-vivo chlorophyll- a fluorescence (chl- a fluo, a proxy of phytoplankton biomass) in surface waters that were obtained during an oceanographic survey in the Argentinian Beagle Channel (subantarctic Atlantic Patagonian) in early fall 2017. The 240 km study transect (centered at 55°S - 67°W) was divided into two zones: (A1) The Beagle Channel innermost portion, semi-enclosed and subject to strong continental influence and (A2) its eastern outlet towards the open Southwest Atlantic. Discrete seawater samples were also collected for apparent oxygen utilization (AOU), nutrients and pH measurements. High-resolution spatial measurements revealed the persistence of p CO 2 below atmospheric equilibrium, increasing in median (interquartile range 25–75%) from 314 μatm in the inner Beagle Channel (A1) to 348 μatm towards the adjacent open sea (A2). A decrease in atmospheric CO 2 sequestration was associated with an increase in water temperature from 9.5 °C to 10.7 °C, salinity from 30.8 to 32.5, and chl- a fluo from 2.24 to 2.91 mg m−3 along the coastal-offshore gradient. Low AOU and nutrient levels were found in regions inside the channel. Indeed, the relationships between CO 2 and temperature or salinity were significantly different from those expected from the theoretical solubility effect, indicating a dominance of metabolic over physicochemical controls on this gas. Moreover, physical factors such as vertical stratification contributed to the variable surface p CO 2 values. These findings reveal the existence of short-scale spatial variability of CO 2 in the Beagle Channel, improving our understanding of the multiple controls on atmospheric carbon sequestration in extensive subpolar continental shelves. • Integrated assessment of metabolic and physicochemical controls on p CO 2. • High short-scale variability of p CO 2 is revealed by the ship measurements. • The Beagle Channel acts as a net CO 2 sink during early fall. • The rate of CO 2 sequestration increases towards the inner regions of the Channel. • The CO 2 surface distribution is dominated by metabolism over physicochemical controls. [ABSTRACT FROM AUTHOR]