Past and future evolution of the marine carbonate system in a coastal zone of the Northern Antarctic Peninsula

Abstract

It is arduous to gather a good spatial and temporal dataset of marine carbonate properties, especially in the Southern Ocean. In this study, we have reconstructed the carbonate system in the Gerlache Strait, a coastal zone of the Northern Antarctic Peninsula. We also analyzed the impact of ocean acidification by calculating the tipping points of the calcium carbonate saturation states and pH (i.e., when saturation state and pH goes below one and 7, respectively). Hydrographic and carbonate data from three distinct data sets (GOAL – 2013–2016, FRUELA – 1996, and World Ocean Database – 1965–2004) have been joined and used to reconstruct the carbonate system from the past 50 years. Temporal annual mean trends were determined depending on the water column depth-layer. The northern Gerlache Strait showed a significant increasing trend of total inorganic carbon concentrations (1.0024 ± 0.34 µmol kg−1) and related pH decreasing trend (−0.0026 ± 0.0009 sws) in the surface mixed layer (> 60 m). The properties variability is relatively different (magnitudes and signs) between the northern and southern sectors of the Gerlache Strait, which indicate that adjacent regions to the Gerlache Strait to the southwest and north, respectively, may major influence the regional carbonate dynamics. Results also show that episodic under-saturation conditions, in relation to aragonite within the surface mixed layer, may already occur, especially in regions close to large glaciers.