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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Differentiating the degradation dynamics of algal and terrestrial carbon within complex natural dissolved organic carbon in temperate lakes
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Differentiating the degradation dynamics of algal and terrestrial carbon within complex natural dissolved organic carbon in temperate lakes

机译：区分温带湖泊中复杂的自然溶解有机碳中藻类和陆地碳的降解动力学

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It has often been hypothesized that the dissolved organic carbon (DOC) pool of algal origin in lakes is more bioavailable than its terrestrial counterpart, but this hypothesis has seldom been directly tested. Here we test this hypothesis by tracking the production and isotopic signature of bacterial respiratory CO_2 in 2 week lake water incubations and use the resulting data to reconstruct and model the bacterial consumption dynamics of algal and terrestrial DOC. The proportion of algal DOC respired decreased systematically over time in all experiments, suggesting a rapid consumption and depletion of this substrate. Our results further show that the algal DOC pool was used in proportions and at rates twice and 10 times as high as the terrestrial DOC pool, respectively. On the other hand, the absolute amount of labile terrestrial DOC was on average four times higher than labile algal DOC, accounting for almost the entire long-term residual C metabolism, but also contributing to short-term bacterial C consumption. The absolute amount of labile algal DOC increased with chlorophyll a concentrations, whereas total phosphorus appeared to enhance the amount of terrestrial DOC that bacteria could consume, suggesting that the degradation of these pools is not solely governed by their respective chemical properties, but also by interactions with nutrients. Our study shows that there is a highly reactive pool of terrestrial DOC that is processed in parallel to algal DOC, and because of interactions with nutrients, terrestrial DOC likely supports high levels of bacterial metabolism and CO_2 production even in more productive lakes.
机译：经常有人提出，湖泊中藻类来源的溶解有机碳（DOC）池比陆地上的藻类具有更高的生物利用度，但是很少有人直接检验这种假设。在这里，我们通过跟踪2周湖水温育过程中细菌呼吸CO_2的产生和同位素特征，并使用所得数据来重构和建模藻类和陆地DOC的细菌消耗动态，来检验该假设。在所有实验中，藻类DOC呼吸的比例随时间系统性降低，表明该底物的快速消耗和消耗。我们的结果进一步表明，藻类DOC库的使用比例和比例分别是陆地DOC库的两倍和10倍。另一方面，不稳定的陆地DOC的绝对量平均比不稳定的藻类DOC高出四倍，几乎占了整个长期残留C代谢的总和，但也导致了短期细菌C的消耗。藻类DOC的绝对含量随叶绿素a浓度的增加而增加，而总磷似乎增加了细菌可消耗的陆地DOC的量，这表明这些库的降解不仅由其各自的化学性质决定，而且还由相互作用决定。有营养。我们的研究表明，与藻类DOC并行处理的陆地DOC具有高反应性，并且由于与养分的相互作用，即使在生产力更高的湖泊中，陆地DOC也可能支持高水平的细菌代谢和CO_2产生。

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