Greenhouse gas emissions from permafrost organic carbon decomposition in lakes and rivers can accelerate global warming. We used radiocarbon (¹⁴C) measurements to determine the predominant sources of dissolved organic carbon (DOC), particulate organic carbon (POC), dissolved inorganic carbon (DIC), and methane (CH₄) in five thermokarst lakes and three rivers in an area of widespread permafrost degradation in Northern Quebec to assess contributions from thawing permafrost and other old carbon (fixed before CE 1950) reservoirs. We compared emission pathways (dissolved gas and ebullition), seasons (summer and winter), and surface soil type (mineral and peat soils). Modern carbon (fixed after CE 1950) was the dominant source of DOC, DIC, and CH₄ of non‐peatland aquatic systems, while POC and sediment carbon were predominantly fixed in the last millennia. In the peatland systems, modern and permafrost carbon were important sources of DOC, lake DIC, lake ebullition CO₂, and lake dissolved CH₄. In contrast, POC, lake ebullition CH₄, and river DIC were dominated by millennial‐old carbon. In winter, the ¹⁴C age of DOC, DIC, and POC in the peatland lakes increased, but the ¹⁴C age of dissolved CH₄ did not change. Our results point to a clearly older overall carbon source for ebullition CH₄ relative to dissolved CH₄ in the peatland lakes but not the non‐peatland lakes. The younger ages of dissolved CH₄ and DIC relative to DOC and POC in all lakes suggest that recent primary productivity strongly influences the large total lake CH₄ and CO₂ emissions in this area, as diffusion fluxes greatly exceed ebullition fluxes.

中文翻译：

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放射性碳数据揭示了加拿大东部热喀斯特喀斯特湖和河流中碳馏分的相反来源（魁北克努纳维克）

湖泊和河流中多年冻土有机碳分解产生的温室气体排放会加速全球变暖。我们使用了放射性碳（¹⁴ C）测量来确定一个热岩溶湖中的五个热喀斯特湖和三个河流中溶解有机碳（DOC），颗粒有机碳（POC），溶解无机碳（DIC）和甲烷（CH ₄）的主要来源。魁北克北部多年冻土广泛退化的地区，以评估融化的多年冻土和其他旧碳（在1950年之前固定）储层的贡献。我们比较了排放途径（溶解的气体和沸腾），季节（夏季和冬季）和表层土壤类型（矿物质和泥炭土）。现代碳（在1950年后固定）是DOC，DIC和CH ₄的主要来源在过去的一千年中，主要是固定了POC和沉积物碳。在泥炭地系统中，现代碳和多年冻土碳是DOC，DIC湖，沸腾湖CO ₂和湖溶解CH _4的重要来源。相比之下，POC，湖泊沸腾CH ₄和河DIC则以千禧世代碳为主。在冬季，¹⁴在泥炭湖泊DOC，DIC，和POC的Ç年龄增加，但¹⁴溶于CH的Ç年龄₄没有变化。我们的结果表明，与溶解的CH ₄相比，沸腾CH _4的总碳源明显更旧在泥炭地湖泊中，但在非草原上则没有。在所有湖泊中，相对于DOC和POC而言，溶解的CH ₄和DIC的年龄都较小，这表明最近的初级生产力极大地影响了该地区大量的总CH ₄和CO ₂排放，因为扩散通量大大超过了沸腾通量。