Accumulation of recalcitrant dissolved organic matter in aerobic aquatic systems
Accumulation of recalcitrant dissolved organic matter in aerobic aquatic systems
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DOI：
10.1002/lol2.10265
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发表时间：
2022-08
影响因子：
7.8
通讯作者：
J. Cotner;N. Anderson;C. Osburn
中科院分区：
文献类型：
--
作者：
J. Cotner;N. Anderson;C. Osburn
富氧大气改变了地球上的生命，但它也通过增加分解速度对有机质的积累提供了负反馈。尽管如此，溶解有机碳是一个巨大的碳库(>；750pg)，它可以在一些淡水水生系统中积累到很高的浓度(20-100mgC L−1)，但原因尚不清楚。在这里，我们研究了几个不同DOC浓度的格陵兰湖泊中的DOC，并确定了可能改变其组成以使其变得越来越顽固的过程。DOC的Δ14C老化对应于DOC浓度的增加、降解速度的减慢、同位素比值和光学性质的变化，所有这些都表明光化学和微生物降解过程导致了顽固性。年轻的DOC降解受到磷的刺激，而年长的DOC没有，这表明养分在降解的早期起着重要的作用。光化学作用加上水文隔离系统中栖息地多样性的减少，可能会使顽固的DOC积累，对地球的碳氧循环产生重要影响。
An oxygenated atmosphere changed life on Earth but it also provided a negative feedback to organic matter accumulation by increasing decomposition rates. Nonetheless, dissolved organic carbon (DOC) is a huge carbon pool (> 750 Pg) and it can accumulate to high concentrations (20–100 mg C L−1) in some freshwater aquatic systems, yet it is not clear why. Here, we examine DOC in several Greenland lakes with varying DOC concentrations and identify processes that could alter its composition to make it increasingly recalcitrant. Δ14C aging of DOC corresponded with increased DOC concentrations, slower degradation rates, changes in isotope ratios and optical properties, all suggesting that photochemical and microbial degradation processes contributed to recalcitrance. Young DOC degradation was stimulated by phosphorus, but older DOC was not, suggesting an important role for nutrients early in degradation. Photochemical processing coupled with decreased habitat diversity in hydrologically isolated systems may enable recalcitrant DOC to accumulate with important implications for Earth's carbon and oxygen cycles.