研究人员展示了在采样不足的东太平洋亚南极区，沿南北样带进行了15个生物测定实验的结果。除了浮游植物光化学效率的广泛铁限制之外，研究人员还在其南部站点发现添加锰后的进一步响应，结果支持了铁-锰共同限制在南大洋的重要性。
此外，研究表明，添加不同的Patagonian尘埃引起光化学效率的提高，在相应的铁/锰溶解度方面，差异响应与源区尘埃特性有关。因此，在未来和过去的气候状态下，结合源区矿物学、尘埃沉积相对量级的变化，可以确定铁或锰的限制是否控制着南大洋的生产力。
据介绍，光和微量营养素的季节性供应强烈地调节着南大洋的生产力，并且限制了大量营养素的生物利用率和CO2的下降。矿物尘埃通量是微量营养素进入南大洋的主要渠道，也是数百万年尺度大气CO2振荡的关键介质。虽然已经详细研究了尘埃携带的铁在南大洋生物地球化学中的作用，但锰的可用性也正在成为过去、现在和未来南大洋生物地球化学的潜在驱动力。
附：英文原文
Title: Phytoplankton responses to dust addition in the Fe–Mn co-limited eastern Pacific sub-Antarctic differ by source region
Author: Wyatt, Neil J., Birchill, Antony, Ussher, Simon, Milne, Angela, Bouman, Heather A., Shoenfelt Troein, Elizabeth, Pabortsava, Katsiaryna, Wright, Alan, Flanagan, Oliver, Bibby, Thomas S., Martin, Adrian, Moore, C. Mark
Issue&Volume: 2023-7-3
Abstract: The seasonal availability of light and micronutrients strongly regulates productivity in the Southern Ocean, restricting biological utilization of macronutrients and CO2 drawdown. Mineral dust flux is a key conduit for micronutrients to the Southern Ocean and a critical mediator of multimillennial-scale atmospheric CO2 oscillations. While the role of dust-borne iron (Fe) in Southern Ocean biogeochemistry has been examined in detail, manganese (Mn) availability is also emerging as a potential driver of past, present, and future Southern Ocean biogeochemistry. Here, we present results from fifteen bioassay experiments along a north–south transect in the undersampled eastern Pacific sub-Antarctic zone. In addition to widespread Fe limitation of phytoplankton photochemical efficiency, we found further responses following the addition of Mn at our southerly stations, supporting the importance of Fe–Mn co-limitation in the Southern Ocean. Moreover, addition of different Patagonian dusts resulted in enhanced photochemical efficiency with differential responses linked to source region dust characteristics in terms of relative Fe/Mn solubility. Changes in the relative magnitude of dust deposition, combined with source region mineralogy, could hence determine whether Fe or Mn limitation control Southern Ocean productivity under future as well as past climate states.
DOI: 10.1073/pnas.2220111120
Source: https://www.pnas.org/doi/10.1073/pnas.2220111120