Export of dissolved organic carbon from peatlands under elevated carbon dioxide levels
Export of dissolved organic carbon from peatlands under elevated carbon dioxide levels
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DOI：
10.1038/nature02707
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发表时间：
2004-07-08
期刊：
影响因子：
64.8
通讯作者：
Hudson, J
中科院分区：
文献类型：
--
作者：
Freeman, C;Fenner, N;Hudson, J
泥炭地代表了全球碳的巨大储存量（1）。对排干泥炭地的河流中溶解的有机碳浓度迅速上升的观察引起了人们对这些储存开始不稳定的担忧（2，3）。三个主要因素已被提出作为潜在的因果机制，但似乎两个替代方案-变暖（2，4）和河流流量增加（3）-不能提供令人满意的解释（5）。在这里，我们表明，第三种机制，即夏季到达的年降雨量比例的变化趋势（6），同样无法解释这一趋势。相反，我们推断，一个以前未被认识到的机制二氧化碳介导的初级生产力的刺激是负责。在二氧化碳浓度升高的情况下，来自最近同化的二氧化碳的溶解有机碳的比例比对照组高出10倍。溶解有机碳的浓度似乎对影响净初级生产力的环境驱动因素比影响分解的环境驱动因素更敏感。
Peatlands represent a vast store of global carbon(1). Observations of rapidly rising dissolved organic carbon concentrations in rivers draining peatlands have created concerns that those stores are beginning to destabilize(2,3). Three main factors have been put forward as potential causal mechanisms, but it appears that two alternatives-warming(2,4) and increased river discharge(3)-cannot offer satisfactory explanations(5). Here we show that the third proposed mechanism, namely shifting trends in the proportion of annual rainfall arriving in summer(6), is similarly unable to account for the trend. Instead we infer that a previously unrecognized mechanism-carbon dioxide mediated stimulation of primary productivity-is responsible. Under elevated carbon dioxide levels, the proportion of dissolved organic carbon derived from recently assimilated carbon dioxide was ten times higher than that of the control cases. Concentrations of dissolved organic carbon appear far more sensitive to environmental drivers that affect net primary productivity than those affecting decomposition alone.