In the boreal and subarctic zone, the moss and peat interactions with rainwater and snowmelt water in shallow surface ponds control the delivery of dissolved organic matter (DOM) and metal to the rivers and further to the Arctic Ocean. The transformation of peat and moss leachate by common aquatic microorganisms and the effect of temperature on DOM mineralization by heterotrophs remain poorly known that does not allow predicting the response of boreal aquatic system to ongoing climate change. We used experimental approach to quantify the impact of boreal aquatic bacteria P. reactans, and two culturable bacteria extracted from a thaw lake of the permafrost zone (Bolshezemelskaya tundra, NE Europe): Iodobacter sp. and cyanobacterial associate dominated by order Chroococcales (Synechococcus sp). The interaction of these bacterial cultures with nutrient-free peat and moss leachate was performed in order to (1) quantify the impact of temperature (4, 25 and 45 °C) on peat leachate processing by heterotrophs; (2) compare the effect of heterotrophic bacteria and cyanobacterial associate on moss and peat leachate chemical composition, and (3) quantify the DOC and metal concentration change during cyanobacterial growth on leachate from frozen and thawed peat horizon and moss biomass. The efficiency of peat DOM processing by two heterotrophs was not modified by temperature rise from 4 to 45 °C. The DOC concentration decreased by a factor of 1.6 during 3 days of moss leachate reaction with Iodobacters sp. or cyanobacterial associate at 25 °C. The SUVA₂₄₅ increased twofold suggesting an uptake of non-aromatic DOM by both microorganisms. The growth of cyanobacteria was absent on peat leachate but highly pronounced on moss leachate. This growth produced tenfold decrease in P concentration, a factor of 1.5–2.0 decrease in DOC, a factor of 4 and 100 decrease in Fe and Mn concentration, respectively. Adsorption of organic and organo-mineral colloids on bacterial cell surface was more important factor of element removal from organic leachates compared to intracellular assimilation and/or Fe oxyhydroxide precipitation. Overall, we demonstrate highly conservative behavior of peat leachate compared to moss leachate in the presence of culturable aquatic bacteria, a lack of any impact of heterotrophs on peat leachate and their weak impact on moss leachate. A very weak temperature impact on DOM processing by heterotrophs and lack of difference in the biodegradability of DOM from thawed and frozen peat horizons contradict the current paradigm that the warming of frozen OM and its leaching to inland waters will greatly affect microbial production and C cycle. Strong decrease in concentration of P, Fe and Mn in the moss leachate in the presence of cyanobacterial associate has straightforward application for understanding the development of thermokarst lakes and suggests that, in addition to P, Fe and Mn may become limiting micronutrients for phytoplankton bloom in thermokarst lakes.

中文翻译：

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蓝藻伴生细菌和异养细菌对苔藓和泥炭渗滤液中溶解的有机碳和金属的影响：在水生环境中多年冻土融化中的应用

在北北极和北极地区，苔藓和泥炭与浅表池塘中的雨水和融雪水的相互作用控制着溶解的有机物（DOM）和金属向河流乃至北冰洋的输送。常见水生微生物对泥炭和苔藓浸出液的转化以及温度对异养菌对DOM矿化的影响仍然知之甚少，这无法预测北方水生系统对正在进行的气候变化的响应。我们使用实验方法量化了北方水生细菌P. Reactans和从多年冻土区（Bolshezemelskaya tundra，欧洲东北部）的融化湖中提取的两种可培养细菌的影响：碘杆菌。和蓝细菌缔合体以色球菌（Synechococcus sp）。进行这些细菌培养物与无营养的泥炭和苔藓渗滤液的相互作用，以便（1）量化温度（4、25和45°C）对异养菌处理泥炭渗滤液的影响；（2）比较异养细菌和蓝细菌缔合物对苔藓和泥炭渗滤液化学成分的影响，（3）量化蓝藻在冷冻和解冻后的泥炭层和苔藓生物量中蓝藻生长过程中DOC和金属浓度的变化。温度从4升高到45°C不会改变两个异养菌对泥炭DOM的处理效率。在苔藓浸出液与碘杆菌属细菌反应的3天中，DOC浓度降低了1.6倍。或在25°C下与蓝细菌缔合。SUVA ₂₄₅增加了两倍，表明两种微生物都吸收了非芳香DOM。泥炭渗滤液中蓝细菌的生长不存在，而苔藓渗滤液中蓝细菌的生长显着。这种生长使磷浓度降低了十倍，DOC降低了1.5-2.0倍，Fe和Mn降低了4倍和100倍。与细胞内同化和/或羟基氧化铁沉淀相比，细菌细胞表面上有机和有机矿物胶体的吸附是去除有机渗滤液中元素的更重要因素。总的来说，在有可培养水生细菌存在的情况下，我们证明了与苔藓浸出液相比，泥炭浸出液具有高度保守的行为，异养菌对泥炭浸出液没有任何影响，而它们对苔藓浸出液的影响较弱。温度对异养菌对DOM处理的影响非常弱，并且解冻和冷冻的泥炭地层中DOM的生物降解性缺乏差异，这与当前的范式相反，即冷冻OM的变暖及其向内陆水的浸出将极大地影响微生物的生产和碳循环。在存在蓝细菌缔合体的情况下，苔藓渗滤液中P，Fe和Mn的浓度大幅降低，可直接用于理解热喀斯特湖的发育，并表明，除了P之外，Fe和Mn可能成为限制浮游植物开花的微量营养元素。热喀斯特湖。