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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Atmospheric nitrogen deposition promotes carbon loss from peat bogs
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Atmospheric nitrogen deposition promotes carbon loss from peat bogs

机译：大气氮沉积促进泥炭沼泽碳的损失

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Peat bogs have historically represented exceptional carbon (C) sinks because of their extremely low decomposition rates and consequent accumulation of plant remnants as peat. Among the factors favoring that peat accumulation, a major role is played by the chemical quality of plant litter itself, which is poor in nutrients and characterized by polyphenols with a strong inhibitory effect on microbial breakdown. Because bogs receive their nutrient supply solely from atmospheric deposition, the global increase of atmospheric nitrogen (N) inputs as a consequence of human activities could potentially alter the litter chemistry with important, but still unknown, effects on their C balance. Here we present data showing the decomposition rates of recently formed litter peat samples collected in nine European countries under a natural gradient of atmospheric N deposition from approximate to 0.2 to 2 g center dot m(-2)center dot yr(-1). We found that enhanced decomposition rates for material accumulated under higher atmospheric N supplies resulted in higher carbon dioxide (CO2) emissions and dissolved organic carbon release. The increased IN availability favored microbial decomposition (i) by removing N constraints on microbial metabolism and (ii) through a chemical amelioration of litter peat quality with a positive feedback on microbial enzymatic activity. Although some uncertainty remains about whether decay-resistant Sphagnum will continue to dominate litter peat, our data indicate that, even without such changes, increased N deposition poses a serious risk to our valuable peatland C sinks.
机译：泥炭沼泽由于其极低的分解速度以及随之而来的植物残渣作为泥炭的积累，在历史上一直代表着特殊的碳（C）汇。在有利于泥炭积累的因素中，植物凋落物本身的化学质量起着主要作用，后者的营养成分不足，且多酚具有对微生物分解的强烈抑制作用。由于沼泽完全是通过大气沉积来获取营养，因此人类活动导致的全球大气氮（N）输入的总体增加可能会改变其垫料化学性质，对其碳平衡产生重要但仍未知的影响。在这里，我们提供的数据显示了在9个欧洲国家/地区中从大气N沉积的自然梯度大约0.2到2 g中心点m（-2）中心点yr（-1）收集的最近形成的垃圾泥炭样品的分解速率。我们发现，在较高的大气N供应下积累的物质的分解速率提高，导致较高的二氧化碳（CO2）排放量和溶解的有机碳释放量。可用氮的增加有利于微生物的分解（i）通过消除微生物代谢中的N限制和（ii）通过化学改善垫料泥炭质量以及对微生物酶活性的正反馈来促进微生物分解。尽管尚不能确定耐腐泥炭藓是否会继续主导垃圾泥炭，但我们的数据表明，即使没有这种变化，氮沉降量的增加也会对我们宝贵的泥炭地C库构成严重威胁。

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