Abstract. The accelerated warming of the Arctic manifests in sea ice loss and melting glaciers, significantly altering the dynamics of marine biota. This disruption in marine ecosystems can lead to the emission of biological ice nucleating particles (INPs) from the ocean into the atmosphere. Once airborne, these INPs induce cloud droplet freezing, thereby affecting cloud lifetime and radiative properties. Despite the potential atmospheric impacts of marine INPs, their properties and sources remain poorly understood. Analysing sea bulk water and the sea surface microlayer in two southwest Greenlandic fjords, collected between June and September 2018, and investigating the INPs along with the microbial communities, we could demonstrate a clear seasonal variation in the number of INPs and a notable input from terrestrial runoff. We found the highest INP concentration in June during the late stage of the phytoplankton bloom and active melting processes causing enhanced terrestrial runoff. These highly active INPs were smaller in size and less heat-sensitive than those found later in the summer and those previously identified in Arctic marine systems. A negative correlation between salinity and INP abundance suggests freshwater input as sources of INPs. Stable oxygen isotope analysis, along with the strong correlation between INPs and the presence of the bacterium Aquaspirillum arcticum, highlighted meteoric water as the primary origin of the freshwater influx, suggesting that the notably active INPs originate from terrestrial sources such as glacial and soil runoff.

中文翻译：

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陆地径流是北极海洋系统生物INP的重要来源


摘要。北极加速变暖表现为海冰消失和冰川融化，显着改变了海洋生物群的动态。海洋生态系统的这种破坏可能导致生物冰核颗粒（INP）从海洋排放到大气中。一旦在空中传播，这些 INP 就会引起云滴冻结，从而影响云的寿命和辐射特性。尽管海洋 INP 具有潜在的大气影响，但对其特性和来源仍然知之甚少。通过分析 2018 年 6 月至 9 月期间收集的格陵兰西南部两个峡湾的海水和海表微层，并调查 INP 和微生物群落，我们可以证明 INP 数量存在明显的季节性变化，并且来自陆地的显着输入径流。我们发现，6 月份 INP 浓度最高，此时正值浮游植物大量繁殖和活跃的融化过程导致陆地径流增强的后期。这些高度活跃的 INP 比夏季晚些时候发现的 INP 和之前在北极海洋系统中发现的 INP 尺寸更小，热敏感性更低。盐度和 INP 丰度之间的负相关表明淡水输入是 INP 的来源。稳定氧同位素分析以及 INP 与北极水螺菌细菌存在之间的强相关性，强调了大气水是淡水流入的主要来源，表明显着活跃的 INP 源自冰川和土壤径流等陆地来源。