Iron is a vital trace metal regulating primary productivity in the Southern Ocean, where high-productivity regions are largely confined to the Antarctic coastal margins. One of the key iron sources in these regions is the ocean–glacier system, including sea ice, icebergs, glaciers, and subglacial meltwater. The Denman Glacier and Mertz Glacier Polynya regions are currently experiencing significant environmental change, which may alter iron inputs and associated biogeochemical cycling.
This study presents a comparative analysis of dissolved iron concentrations and isotopic compositions in the water columns of the Denman Glacier and Mertz Glacier Polynya regions. The Mertz Glacier Polynya shows pronounced spatial variability, with shallower, open-ocean-influenced stations exhibiting lighter iron isotope signatures (mean δ56Fe ≈ −1.16‰), accompanied by heavier zinc isotopes (mean δ66Zn ≈ 0.55‰) and elevated zinc concentrations. In contrast, the Denman Glacier region displays relatively homogeneous iron isotope distributions, with consistently negative values (−1.5‰ to −2.5‰) and limited concentration variability.
Contrasting patterns suggest differing dominant iron sources and transformation processes between the two regions. Ongoing work integrates regional oceanographic and biogeochemical processes to further constrain these mechanisms and improve understanding of iron isotope cycling in the Southern Ocean.