TY - JOUR

T1 - Continued glacial retreat linked to changing macronutrient supply along the West Antarctic Peninsula.

AU - Jones, Rhiannon

AU - Meredith, Michael

AU - Lohan, Maeve

AU - Woodward, E. Malcolm

AU - Van Landeghem, Katrien

AU - Retallick, Kate

AU - Flanagan, Oliver

AU - Vora, Mehul

AU - Annett, Amber

PY - 2023/4/20

Y1 - 2023/4/20

N2 - At the West Antarctic Peninsula (WAP), continued atmospheric and oceanic warming is causing significant physical and biogeochemical changes to glaciers and the marine environment. We compare sediment sources and drivers of macronutrient distributions at two bays along the WAP during austral summer 2020, using radioactive radium and stable oxygen isotopes to trace sedimentary influences and quantify different freshwater inputs. In the Ryder Bay, where the Sheldon Glacier is marine-terminating, radium activities at the sediment-water interface indicate considerable benthic mixing. Using radium isotope activity gradients to resolve radium and macronutrient fluxes, we find buoyant meltwater proximal to the glacier drives vigorous mixing of sediment and entrainment of macronutrient deep waters, on the order of 2.0 × 105 mol d-1 for nitrate. Conversely, in the Marian Cove, where the Fourcade Glacier terminates on land, low salinities and oxygen isotopes indicate a meltwater-rich surface layer < 1 m thick and rich in sediment, and strong vertical mixing to the seafloor. A continued shift to land-terminating glaciers along the WAP may have a significant impact upon nutrient and sediment supply to the euphotic zone, with impacts upon primary productivity and carbon uptake efficiency. The future of primary production, carbon uptake, and food web dynamics is therefore linked to glacier retreat dynamics in the many fjords along the WAP.

AB - At the West Antarctic Peninsula (WAP), continued atmospheric and oceanic warming is causing significant physical and biogeochemical changes to glaciers and the marine environment. We compare sediment sources and drivers of macronutrient distributions at two bays along the WAP during austral summer 2020, using radioactive radium and stable oxygen isotopes to trace sedimentary influences and quantify different freshwater inputs. In the Ryder Bay, where the Sheldon Glacier is marine-terminating, radium activities at the sediment-water interface indicate considerable benthic mixing. Using radium isotope activity gradients to resolve radium and macronutrient fluxes, we find buoyant meltwater proximal to the glacier drives vigorous mixing of sediment and entrainment of macronutrient deep waters, on the order of 2.0 × 105 mol d-1 for nitrate. Conversely, in the Marian Cove, where the Fourcade Glacier terminates on land, low salinities and oxygen isotopes indicate a meltwater-rich surface layer < 1 m thick and rich in sediment, and strong vertical mixing to the seafloor. A continued shift to land-terminating glaciers along the WAP may have a significant impact upon nutrient and sediment supply to the euphotic zone, with impacts upon primary productivity and carbon uptake efficiency. The future of primary production, carbon uptake, and food web dynamics is therefore linked to glacier retreat dynamics in the many fjords along the WAP.

KW - Radium

KW - Macronutrient cycling

KW - Glacial retreat

KW - West Antarctic Peninsula

U2 - 10.1016/j.marchem.2023.104230

DO - 10.1016/j.marchem.2023.104230

M3 - Article

VL - 251

JO - Marine Chemistry

JF - Marine Chemistry

SN - 0304-4203

M1 - 104230

ER -