GET (Géosciences Environnement Toulouse) UMR 5563 CNRS, University of Toulouse, 14 Avenue Edouard Belin, 31400 Toulouse, France; Institute of Ecological Problems of the North, Federal Center of Arctic Research, 23 Nab. Severnoi Dviny, Arkhangelsk, Russia.
Institute of Ecological Problems of the North, Federal Center of Arctic Research, 23 Nab. Severnoi Dviny, Arkhangelsk, Russia.
Sci Total Environ. 2021 Aug 15;782:146737. doi: 10.1016/j.scitotenv.2021.146737. Epub 2021 Mar 29.
Permafrost thaw in continental lowlands produces large number of thermokarst (thaw) lakes, which act as a major regulator of carbon (C) storage in sediments and C emission in the atmosphere. Here we studied thaw lakes of the NE European permafrost peatlands - shallow water bodies located within frozen peat bogs and receiving the majority of their water input from lateral (surface) runoff. We also conducted mesocosm experiments via interacting lake waters with frozen peat and dominant ground vegetation - lichen and moss. There was a systematic decrease in concentrations of dissolved C, CO, nutrients and metals with an increase in lake size, corresponding to temporal evolution of the water body and thermokarst development. We hypothesized that ground vegetation and frozen peat provide the majority of C, nutrients and inorganic solutes in the water column of these lakes, and that microbial processing of terrestrial organic matter controls the pattern of CO and nutrient concentrations in thermokarst lakes. Substrate mass-normalized C, nutrient (N, P, K), major and trace metal release was maximal in moss mesocosms. After first 16 h of reaction, the pCO increased ten-fold in mesocosms with moss and lichen; this increase was much less pronounced in experiments with permafrost peat. Overall, moss and lichen were the dominant factors controlling the enrichment of the lake water in organic C, nutrients, and trace metals and rising the CO concentration. The global significance of obtained results is that the changes in ground vegetation, rather than mere frozen peat thawing, may exert the primary control on C, major and trace element balance in aquatic ecosystems of tundra peatlands under climate warming scenario.
大陆低地的永久冻土解冻会产生大量热喀斯特（解冻）湖泊，这些湖泊是沉积物中碳（C）储存和大气中 C 排放的主要调节者。在这里，我们研究了东北欧永久冻土泥炭地的解冻湖泊——位于冰冻泥炭沼泽内的浅水湖泊，其大部分水源来自侧向（表面）径流。我们还通过将湖水与冰冻泥炭和主要地被植被——地衣和苔藓相互作用进行了中观实验。随着湖泊面积的增大，溶解 C、CO、养分和金属的浓度呈系统下降趋势，这与水体的时间演变和热喀斯特的发展相对应。我们假设地被植被和冰冻泥炭为这些湖泊水柱中的大部分 C、养分和无机溶质提供了来源，并且陆地有机物质的微生物处理控制了热喀斯特湖泊中 CO 和养分浓度的模式。以基质质量归一化的 C、养分（N、P、K）、主要和微量元素释放量在苔藓中观实验中最大。在与苔藓和地衣反应的前 16 小时，中观实验中的 pCO 增加了十倍；在与永久冻土泥炭的实验中，这种增加要小得多。总体而言，苔藓和地衣是控制湖泊水中有机 C、养分和痕量金属富化以及 CO 浓度升高的主要因素。研究结果的全球意义在于，在气候变暖的情景下，地面植被的变化，而不仅仅是冰冻泥炭的解冻，可能会对苔原地泥炭地水生生态系统中的 C、主要和微量元素平衡产生主要的控制作用。
