| Autor: |
Santos‐Andrade, Maurício, Kerr, Rodrigo, Orselli, Iole B. M., Monteiro, Thiago, Mata, Mauricio M., Goyet, Catherine |
| Předmět: |
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| Zdroj: |
Global Biogeochemical Cycles; Mar2023, Vol. 37 Issue 3, p1-22, 22p |
| Abstrakt: |
The Bransfield Strait is a climate change hotspot at the tip of the northern Antarctic Peninsula (NAP). The region is marked by a mixture of relatively warm waters from the Bellingshausen Sea with cold shelf waters from the Weddell Sea. Additionally, its deep central basin (>800 m) preserves seawater properties from the north‐western Weddell Sea continental shelf. This study assessed long‐term changes in carbonate chemistry in the Bransfield Strait and found that the hydrographic setting (i.e., a mixture between modified‐Circumpolar Deep Water with Dense Shelf Water [DSW]) drives temporal variability of carbonate parameters. The western basin has experienced decreases in pH (seawater scale) over the last three decades (1996–2019), varying from −0.003 to −0.017 pH units yr−1, while Ωar decreased from −0.01 to −0.07 yr−1 throughout the water column. The central basin was characterized by a high contribution of DSW with high carbon dioxide (CO2) content and the decomposition of organic matter produced and transported into its deep layer. With lower variability for all carbonate system variables, the eastern basin was likely regulated by internal mixing. Overall, the entire strait is almost reaching a CO2‐saturated condition, highlighting how sensitive subpolar regions are to the effects of human‐induced climate change. Plain Language Summary: Although the entire world is experiencing the impacts of climate change, they may be occurring more rapidly in some regions, such as the northern Antarctic Peninsula. At the northern tip of this area is the Bransfield Strait, which can act as a sentinel for identifying what is happening around the peninsula during modern climate change. Areas of the strait that are connected to the open ocean showed a more rapid increase in acidification over time than areas mainly influenced by coastal zones. This occurs because the contribution of open‐ocean water masses supplies a signature of the decomposition of organic particles from the ocean around Antarctica. On the other hand, coastal zones are more influenced by atmospheric carbon dioxide from human activities. The steeper acidification trends in the Bransfield Strait draw our attention to the effects of climate change on ocean acidification and its biological and chemical impacts on the ocean. Moreover, there are many areas, such as the Bransfield Strait, for which there are few studies about these effects, which delays the identification of severe impacts even after changes have already been experienced, as was found in our assessment. Key Points: The western basin experiences steeper pH decreases than the surrounding areas at a rate of −0.017 pHsws units yr−1 due to Circumpolar Deep Water intrusionsDense Shelf Water inflow into the deep layer of the central basin promoted a CT increase of about 50 μmol kg−1 in the 2010s relative to the 2000sInternal mixing has likely reduced spatiotemporal variability of carbonate chemistry in the eastern basin since the 1990s [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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