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<p>Antarctic coastal polynyas are among the most productive regions in the Southern Ocean, playing a crucial role in maintaining ecosystem stability and sequestering atmospheric CO<sub>2</sub>. To support high primary production, glacial meltwater (GMW) significantly contributes iron (Fe) to these coastal polynyas. However, the flux of exported Fe is poorly constrained due to the rapid recycling of Fe in the euphotic zone. In this study, we investigate the utilization of <sup>228</sup>Ra as a tracer for GMW-derived Fe inputs in Antarctic coastal polynyas. Our results show that <sup>228</sup>Ra exhibits significantly higher activities [(0.17 ± 0.06) Bq/m<sup>3</sup>]within the coastal polynyas compared to those outside [(0.04 ± 0.04) Bq/m<sup>3</sup>]. The elevated <sup>228</sup>Ra activities suggest GMW inputs within the polynyas, consistent with the distribution of δ<sup>18</sup>O. Stimulated by GMW-derived Fe, primary production was enhanced. Moreover, chlorophyll <i>a</i> (Chl <i>a</i>) concentrations positively correlate with <sup>228</sup>Ra activities in the polynyas, indicating that GMW contributed Fe and <sup>228</sup>Ra in a fixed ratio. Based on these findings, our study highlights the potential of <sup>228</sup>Ra as a proxy for quantifying the inputs of Fe derived from GMW in Antarctica.</p>

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Radium-228 reveals glacial meltwater enhancing biological productivity in Antarctic coastal polynyas

  • 期刊论文

  • 发表日期：

    2026年7月20日

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  • Guanghui Chen,
  • You Jiang,
  • Yi Wang,
  • Zifei Yang,
  • Zhen Tang,
  • Shunan Cao,
  • Minfang Zheng,
  • Mengya Chen,
  • Jianfeng He,
  • Min Chen

摘要

Antarctic coastal polynyas are among the most productive regions in the Southern Ocean, playing a crucial role in maintaining ecosystem stability and sequestering atmospheric CO2. To support high primary production, glacial meltwater (GMW) significantly contributes iron (Fe) to these coastal polynyas. However, the flux of exported Fe is poorly constrained due to the rapid recycling of Fe in the euphotic zone. In this study, we investigate the utilization of 228Ra as a tracer for GMW-derived Fe inputs in Antarctic coastal polynyas. Our results show that 228Ra exhibits significantly higher activities [(0.17 ± 0.06) Bq/m3]within the coastal polynyas compared to those outside [(0.04 ± 0.04) Bq/m3]. The elevated 228Ra activities suggest GMW inputs within the polynyas, consistent with the distribution of δ18O. Stimulated by GMW-derived Fe, primary production was enhanced. Moreover, chlorophyll a (Chl a) concentrations positively correlate with 228Ra activities in the polynyas, indicating that GMW contributed Fe and 228Ra in a fixed ratio. Based on these findings, our study highlights the potential of 228Ra as a proxy for quantifying the inputs of Fe derived from GMW in Antarctica.