Iron-mediated soil carbon response to water-table decline in an alpine wetland.
Iron-mediated soil carbon response to water-table decline in an alpine wetland.
复制标题
铁介导的土壤碳对高山湿地地下水位下降的反应
DOI：
10.1038/ncomms15972
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发表时间：
2017-06-26
影响因子：
16.6
通讯作者：
Feng X
中科院分区：
文献类型：
--
作者：
Wang Y;Wang H;He JS;Feng X
湿地中巨大的土壤有机碳（SOC）库正受到全球地下水位下降（WTD）的威胁。然而，SOC 对 WTD 的反应仍然高度不确定。在这里，我们在高山湿地的中生态 WTD 实验中研究了铁 (Fe) 在介导土壤酶活性和木质素稳定性方面的尚未充分研究的作用。与经典的“酶锁”理论相反，苯酚氧化活性主要受亚铁[Fe(II)]控制，并随着WTD的增加而下降，导致可溶解芳香族化合物的积累和水解酶活性的降低。此外，使用连二亚硫酸盐去除铁氧化物，我们观察到暴露在空气中的土壤中受铁保护的木质素酚显着增加。因此，Fe 氧化在氧气暴露下调节湿地 SOC 动态方面充当了对抗“酶锁”的“铁门”。这种新认识的机制可能是预测气候变化中 WTD 增强的湿地土壤碳储存的关键。
The tremendous reservoir of soil organic carbon (SOC) in wetlands is being threatened by water-table decline (WTD) globally. However, the SOC response to WTD remains highly uncertain. Here we examine the under-investigated role of iron (Fe) in mediating soil enzyme activity and lignin stabilization in a mesocosm WTD experiment in an alpine wetland. In contrast to the classic ‘enzyme latch’ theory, phenol oxidative activity is mainly controlled by ferrous iron [Fe(II)] and declines with WTD, leading to an accumulation of dissolvable aromatics and a reduced activity of hydrolytic enzyme. Furthermore, using dithionite to remove Fe oxides, we observe a significant increase of Fe-protected lignin phenols in the air-exposed soils. Fe oxidation hence acts as an ‘iron gate’ against the ‘enzyme latch’ in regulating wetland SOC dynamics under oxygen exposure. This newly recognized mechanism may be key to predicting wetland soil carbon storage with intensified WTD in a changing climate.