Around 50% of the world's lakes freeze seasonally, but the duration of ice-cover is shortening each year and this is likely to have broad limnological consequences. We sampled freshwater ice and the underlying water in 19 boreal and polar lakes to evaluate whether lake ice contains an inoculum of algae, nutrients, and carbon that may contribute to lake ecosystem productivity. Boreal and Arctic lakes differed in ice duration (6 vs. >10 months), thickness (70 vs. 190 cm), and quality (predominantly snow ice vs. black ice), but in all lakes, there were consistent differences in biological and biogeochemical composition between ice and water. Particulate fractions were often more retained while most dissolved compounds were excluded from the ice; for example, the ice had more terrestrial particulate carbon, measured as fatty acid biomarkers (averages of 1.1 vs. 0.3 µg L⁻¹) but lower dissolved organic carbon (2.2 vs. 5.7 mg C L⁻¹) and inorganic phosphorus concentrations (4.0 vs. 7.5 µg C L⁻¹) than the underlying water. The boreal ice further had three times higher chlorophyll-a, than the water (0.9 vs. 0.3 µg L⁻¹). Of the dissolved fractions, the contribution of protein-like compounds was higher in the ice, and this in all lakes. These labile compounds would become available to planktonic microbes when the ice melts. Our results show that freshwater ice has an underestimated role in storage and transformation in the biogeochemical carbon cycle of ice-covered lake ecosystems.

中文翻译：

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北部湖冰中有机物质的隐藏储存：陆地颗粒、浮游植物和不稳定碳的选择性保留

世界上大约 50% 的湖泊季节性结冰，但冰盖的持续时间每年都在缩短，这可能会产生广泛的湖沼学后果。我们对 19 个北方和极地湖泊中的淡水冰和底层水进行了采样，以评估湖冰中是否含有藻类、营养物和碳的接种物，这些藻类、营养物和碳可能有助于湖泊生态系统生产力。北方和北极湖泊在结冰时间（6 个月 vs. > 10 个月）、厚度（70 厘米 vs. 190 厘米）和质量（主要是雪冰 vs. 黑冰）方面存在差异，但在所有湖泊中，生物和冰和水之间的生物地球化学组成。颗粒部分通常被更多地保留，而大多数溶解的化合物被排除在冰之外；例如，冰有更多的陆地颗粒碳，^-1 )，但溶解有机碳（2.2 对 5.7 mg C L ^-1）和无机磷浓度（4.0 对 7.5 µg C L ^-1）低于底层水。寒带冰进一步有三次更高叶绿素A，比水（0.9与0.3微克大号^-1）。在溶解的部分中，蛋白质类化合物在冰中的贡献更高，在所有湖泊中都是如此。当冰融化时，这些不稳定的化合物将可用于浮游微生物。我们的研究结果表明，淡水冰在冰覆盖的湖泊生态系统的生物地球化学碳循环中的储存和转化作用被低估了。