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Spatiotemporal variability of dissolved inorganic macronutrients along the northern Antarctic Peninsula
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  • Thiago Monteiro,
  • Sian Frances Henley,
  • Ricardo César Gonçalves Pollery,
  • Carlos Rafael Borges Mendes,
  • Mauricio M Mata,
  • Virginia Maria Tavano,
  • Carlos A E Garcia,
  • Rodrigo Kerr
Thiago Monteiro
Universidade Federal do Rio Grande

Corresponding Author:[email protected]

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Sian Frances Henley
University of Edinburgh
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Ricardo César Gonçalves Pollery
Universidade Federal do Rio de Janeiro (UFRJ)
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Carlos Rafael Borges Mendes
Universidade Federal do Rio Grande
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Mauricio M Mata
Universidade Federal do Rio Grande-FURG
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Virginia Maria Tavano
Universidade Federal do Rio Grande
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Carlos A E Garcia
Universidade Federal do Rio Grande
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Rodrigo Kerr
Universidade Federal do Rio Grande - FURG
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Abstract

The northern Antarctic Peninsula (NAP) is a key region of the Southern Ocean due to its complex ocean dynamics, distinct water mass sources, and the climate-driven changes taking place in the region. Despite the importance of macronutrients in fuelling primary production and driving the strong carbon uptake and storage, little is known about their spatiotemporal variability along the NAP. Hence, we explored a 24-year time series in this region, primarily sampled by the Brazilian High Latitude Group, to understand the processes involved in the spatial and interannual variability of macronutrients. We found high macronutrients concentrations, even in surface waters and under strong phytoplankton blooms. Minimum concentrations of dissolved inorganic nitrogen (16 μmol/ kg), phosphate (0.7 μmol/kg), and silicic acid (40 μmol/kg) along the NAP are higher than those recorded in surrounding regions. The main source of macronutrients is the intrusions of modified Circumpolar Deep Water (mCDW), and this is enhanced by local sources, such as organic matter remineralisation, water mass mixing, and mesoscale structures. However, we identified a depletion in silicic acid due to influence of Dense Shelf Water (DSW) from the Weddell Sea. Macronutrient concentrations shows substantial interannual variability driven by the balance between the intrusions of mCDW and advection of DSW, which is largely modulated by the Southern Annular Mode and to some extent by El Niño-Southern Oscillation. These findings are critical to improving our understanding of the natural variability of this Southern Ocean ecosystem and how it is responding to climate changes. Associate Editor