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<p>The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle, influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean. However, the impact of variability in the timing of seasonal sea ice retreat on the flux and composition of sinking particulate matter remains to be elucidated. In this study, we deployed sediment traps in Prydz Bay during the austral summers of 2019/2020 and 2020/2021, noting that sea ice melting occurred approximately one and a half months earlier in the former summer compared to the latter. We analyzed sediment trap data, which included total mass flux (TMF), particulate organic carbon (POC), biogenic silica (BSi), particulate inorganic carbon, and lithogenic particle (Litho) fluxes, as well as the stable isotopes δ<sup>13</sup>C and δ<sup>15</sup>N of particulate organic matter (POM). Additionally, we incorporated remote sensing data on sea ice concentration and chlorophyll <i>a.</i> This dramatic delay in sea ice melting timing could result in a significant increase in TMF, BSi and POC fluxes in the summer of 2020/2021 compared to 2019/2020. Elevated BSi fluxes and more <sup>13</sup>C-depleted POC in the austral summer of 2020/2021 suggest that the delayed melting of sea ice may have stimulated the productivity of centric diatoms. Furthermore, the higher BSi/POC ratio and more negative δ<sup>15</sup>N values of POM, along with a reduced presence of krill in the traps, indicate a diminished grazing pressure from zooplankton, which collectively enhanced the sedimentation efficiency of POC during the austral summer of 2020/2021. These findings highlight the critical role of sea ice melting timing in regulating productivity, flux and composition of sinking particulate matter in the Prydz Bay ecosystem, with significant implications for carbon cycling in polar oceans.</p>

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Influence of austral summer sea ice melting timing on particle fluxes and composition in Prydz Bay, East Antarctica

  • 期刊论文

  • 发表日期：

    2025年4月1日

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  • Changfeng Zhu,
  • Yufei Ding,
  • Wenhao Huang,
  • Jun Zhao,
  • Dong Li,
  • Haifeng Zhang,
  • Yanhong Xu,
  • Cai Zhang,
  • Ji Hu,
  • Shunan Cao,
  • Guangfu Luo,
  • Yongming Sun,
  • Haitao Ding,
  • Wei Zhang,
  • Weiping Sun,
  • Jianming Pan,
  • Jianfeng He

摘要

The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle, influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean. However, the impact of variability in the timing of seasonal sea ice retreat on the flux and composition of sinking particulate matter remains to be elucidated. In this study, we deployed sediment traps in Prydz Bay during the austral summers of 2019/2020 and 2020/2021, noting that sea ice melting occurred approximately one and a half months earlier in the former summer compared to the latter. We analyzed sediment trap data, which included total mass flux (TMF), particulate organic carbon (POC), biogenic silica (BSi), particulate inorganic carbon, and lithogenic particle (Litho) fluxes, as well as the stable isotopes δ13C and δ15N of particulate organic matter (POM). Additionally, we incorporated remote sensing data on sea ice concentration and chlorophyll a. This dramatic delay in sea ice melting timing could result in a significant increase in TMF, BSi and POC fluxes in the summer of 2020/2021 compared to 2019/2020. Elevated BSi fluxes and more 13C-depleted POC in the austral summer of 2020/2021 suggest that the delayed melting of sea ice may have stimulated the productivity of centric diatoms. Furthermore, the higher BSi/POC ratio and more negative δ15N values of POM, along with a reduced presence of krill in the traps, indicate a diminished grazing pressure from zooplankton, which collectively enhanced the sedimentation efficiency of POC during the austral summer of 2020/2021. These findings highlight the critical role of sea ice melting timing in regulating productivity, flux and composition of sinking particulate matter in the Prydz Bay ecosystem, with significant implications for carbon cycling in polar oceans.