Dr. Yuncong Ge, a postdoctoral researcher at the School of Oceanography, Shanghai Jiao Tong University, recently published a research paper in Geophysical Research Letters titled “Distinct Distribution Patterns of Dissolved and Particulate Trace Metals in Surface Waters of the Amundsen Sea: From Polynya to Open Waters.” Dr. Yuncong Ge is the first author, Dr. Ruifeng Zhang is the corresponding author, and the School of Oceanography at Shanghai Jiao Tong University serves as the first institution.

Trace metals are essential micronutrients that regulate marine primary productivity and carbon cycling in the Southern Ocean. Iron is widely recognized as a key limiting nutrient in this region, while other trace metals, including manganese, zinc, nickel, copper, cadmium, and lead, can also influence phytoplankton growth, elemental uptake, particle formation, and carbon export. However, the ecological roles of these metals depend not only on their concentrations, but also on how they are partitioned among dissolved, labile particulate, and refractory particulate phases.

The Amundsen Sea is a highly productive Antarctic marginal sea characterized by strong environmental contrasts among polynya, sea-ice-influenced, and open-ocean waters. It is also affected by modified Circumpolar Deep Water intrusion, shelf sediment resuspension, ice-shelf meltwater, and sea-ice processes, making it an ideal natural laboratory for investigating trace metal cycling under a changing climate. Based on samples collected during the 38th Chinese National Antarctic Research Expedition, this study measured seven trace metals—Mn, Fe, Ni, Cu, Zn, Cd, and Pb—in dissolved, labile particulate, and refractory particulate phases. Shipboard iron-addition incubation experiments were also conducted at 14 stations to evaluate the biological responses of phytoplankton across different environmental regimes.

Figure 1. Environmental setting and Fe‐addition incubation responses in the Amundsen Sea.

The study found that trace metal cycling in the Amundsen Sea does not follow a simple nearshore-to-offshore decreasing pattern. Instead, it shows pronounced regional and element-specific differences. In the Amundsen Sea Polynya, total Fe, Cu, Zn, and Pb were enriched, reflecting combined supplies from deep-water upwelling, shelf sediment resuspension, and ice-shelf-influenced waters. This relatively strong iron supply was consistent with the limited response of phytoplankton growth to additional iron in the polynya. In the sea-ice zone, selective iron enrichment suggested that sea-ice melt may preferentially supply Fe rather than multiple trace metals simultaneously. In contrast, the open-ocean region showed weaker external metal inputs, and iron-addition experiments indicated a stronger phytoplankton response to iron addition, suggesting more pronounced iron limitation.

Figure 2. Schematic illustration of trace metal supply, phase partitioning, and controlling mechanisms across the Amundsen Sea from the polynya to the open-ocean region.

Phase partitioning further revealed distinct controlling mechanisms among different metals. Fe and Cu were broadly influenced by lithogenic inputs and particle scavenging across the study region, whereas Ni and Cd were more closely associated with biological particles and phytoplankton-related processes. Mn and Zn showed stronger regional transitions: they were more tightly linked to lithogenic particles and scavenging processes in the polynya, but became increasingly associated with biological uptake and internal cycling toward the sea-ice zone and open-ocean waters. Pb was affected by both external inputs and biogenic particle-mediated scavenging.

These findings demonstrate that future changes in West Antarctic ice-shelf melting, sea-ice dynamics, and deep-water intrusion may alter not only the magnitude of trace metal supply, but also the relative proportions and chemical partitioning of different metals. Such changes may further influence phytoplankton productivity, community structure, and carbon export in Antarctic marginal seas. This study provides new process-based insights into Southern Ocean micronutrient cycling and its ecological implications under climate change.

This research was supported by the National Natural Science Foundation of China (Grant 42506034); the Chinese Arctic and Antarctic Administration (GrantIRASCC2020‐2022‐01‐02‐01B and 01‐01‐02A); the project "Ocean Negative Carbon Emission (ONCE)"; the project "Southern Ocean Microbiome and Geochemistry (SOMG)"; the Shanghai Frontiers Science Center of Polar Science (SCOPS).

Paper link: https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2026GL124120