Processes controlling DOC in pore water during simulated drought cycles in six different UK peats
Processes controlling DOC in pore water during simulated drought cycles in six different UK peats
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DOI：
10.1007/s10533-011-9624-9
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发表时间：
2012-07-01
期刊：
影响因子：
4
通讯作者：
Bottrell, S. H.
中科院分区：
文献类型：
--
作者：
Clark, J. M.;Heinemeyer, A.;Bottrell, S. H.
在泥炭地溶解有机碳（DOC）动态的影响，间歇性干旱一直是相当大的争论的主题，分解和DOC生产被认为是在有氧条件下增加，但减少DOC浓度已观察到在干旱期间。由于硫（S）氧化还原反应驱动的干旱引起的酸化导致DOC溶解度降低，已被认为是一种因果机制;然而，证据是基于在少数地点进行的有限数量的研究。为了验证这一假设的范围内不同的泥炭，我们进行了控制干旱模拟实验泥炭核心收集来自英国各地的六个网站。我们的数据显示，硫酸盐（SO 4）的同时增加和DOC在所有网站在模拟地下水位下降下降，虽然SO 4和DOC之间的关系的幅度不同的网站。相反，我们发现了一致的关系，在所有网站之间的DOC减少和酸化测量的孔隙水酸中和能力（ANC）。ANC提供了一个更一致的措施干旱引起的酸化比SO 4单独，因为它占基地阳离子和酸阴离子浓度之间的差异网站。再湿润导致DOC的快速增加，而不同时增加土壤呼吸，这表明DOC的变化主要是由土壤酸度，而不是土壤生物。这些结果突出了需要在泥炭地的水文驱动的化学和生物过程的综合分析，以提高我们的理解和能力来预测大气污染和不断变化的气候条件之间的相互作用，从情节到区域和全球尺度。
The effect of episodic drought on dissolved organic carbon (DOC) dynamics in peatlands has been the subject of considerable debate, as decomposition and DOC production is thought to increase under aerobic conditions, yet decreased DOC concentrations have been observed during drought periods. Decreased DOC solubility due to drought-induced acidification driven by sulphur (S) redox reactions has been proposed as a causal mechanism; however evidence is based on a limited number of studies carried out at a few sites. To test this hypothesis on a range of different peats, we carried out controlled drought simulation experiments on peat cores collected from six sites across Great Britain. Our data show a concurrent increase in sulphate (SO4) and a decrease in DOC across all sites during simulated water table draw-down, although the magnitude of the relationship between SO4 and DOC differed between sites. Instead, we found a consistent relationship across all sites between DOC decrease and acidification measured by the pore water acid neutralising capacity (ANC). ANC provided a more consistent measure of drought-induced acidification than SO4 alone because it accounts for differences in base cation and acid anions concentrations between sites. Rewetting resulted in rapid DOC increases without a concurrent increase in soil respiration, suggesting DOC changes were primarily controlled by soil acidity not soil biota. These results highlight the need for an integrated analysis of hydrologically driven chemical and biological processes in peatlands to improve our understanding and ability to predict the interaction between atmospheric pollution and changing climatic conditions from plot to regional and global scales.