Silicon (Si) exports from terrestrial to marine systems can dictate phytoplankton species composition in Arctic coastal waters. Diatoms are often the dominant autotroph in Arctic waters, making Si an important control on Arctic marine primary productivity. Yet even as Arctic regions are among the fastest warming on Earth, we lack baseline knowledge on the magnitudes and controls of Arctic river Si exports. To address uncertainties in current and future Si behavior, we used a combination of field data and modeling to quantify daily yields of dissolved Si (DSi) and biogenic Si (BSi) from a 400 km space‐for‐time latitudinal gradient of seven basins across the boreal‐Arctic transition in Alaska (United States) over the course of 2 years (2015–2016). Mean annual DSi concentrations (33–149 μM) and yields (13–49 kmol km⁻² year⁻¹) were significantly and positively correlated with mean basin active layer depth, indicating that permafrost thaw will likely increase DSi fluxes to Arctic coastal waters. Conversely, BSi concentrations (7–16 μM) and yields (2.6–4.5 kmol km⁻² year⁻¹) were more uniform across the seven basins, indicating that warming may not substantially alter BSi loads to coastal systems in the near future. Our data also indicate that climatic warming will advance the timing of Si delivery to coastal waters in the spring, although the ratios of Si to nitrogen in Arctic river exports will likely remain steady. These results highlight the important role of basin hydrology, largely driven by permafrost extent, as a key driver of Si exchange at the land‐sea interface in the Arctic.

中文翻译：

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北极河溶解和生物硅出口-随着气候变暖的现状和未来变化

从陆地到海洋系统的硅（Si）出口可能决定了北极沿海水域的浮游植物物种组成。硅藻通常是北极水域中主要的自养生物，使硅成为控制北极海洋初级生产力的重要手段。然而，即使北极地区是地球上变暖最快的地区之一，我们仍缺乏关于北极河Si出口量和控制方式的基础知识。为了解决当前和未来硅行为的不确定性，我们使用了现场数据和模型的组合来定量分析横跨七个盆地的400 km时空纬度梯度中的溶解硅（DSi）和生物硅（BSi）的日产量历时2年（2015-2016年）在阿拉斯加（美国）进行了北极-北极过渡。平均年DSi浓度（33–149μM）和单产（13–49 kmol km ^-2- ^1年）与平均盆地活动层深度呈显着正相关，表明多年冻土融化将可能增加向北极沿海水域的DSi通量。相反，BSi浓度（7–16μM）和产量（2.6–4.5 kmol km - ²年^-1）在七个盆地中的分布更加均匀，这表明在不久的将来变暖可能不会显着改变海岸系统的BSi负荷。我们的数据还表明，尽管北极河出口中硅与氮的比例很可能保持稳定，但气候变暖将在春季提前将硅运往沿海水域的时间。这些结果凸显了在很大程度上受多年冻土影响的盆地水文学的重要作用，它是北极陆海界面硅交换的关键驱动力。