Dynamics of dissolved organic 14C in throughfall and soil solution of a Norway spruce forest
Dynamics of dissolved organic 14C in throughfall and soil solution of a Norway spruce forest
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DOI：
10.1007/s10533-010-9526-2
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发表时间：
2011-11
期刊：
影响因子：
4
通讯作者：
K. Schulze;W. Borken;E. Matzner
中科院分区：
文献类型：
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作者：
K. Schulze;W. Borken;E. Matzner
溶解有机碳（DOC）是森林生态系统碳循环的重要组成部分，但人们对DOC在径流和土壤溶液中的动态和来源知之甚少。在一项为期 2 年的研究中，我们分析了挪威云杉林中灰化土上 Oa 地平线以下 90 厘米深度的径流和土壤溶液中 DOC 的放射性碳特征。两池混合模型显示，贯穿瀑布的 DOC 主要由生物碳组成，即最近固定的碳，来自树冠淋滤和可能的其他来源。大气沉降中的化石 DOC 对径流 DOC 的贡献平均为 6%，在休眠季节最高为 8-11%。在Oa层位的土壤溶液中，DO14C特征是高度动态的（范围从-8‰到+103‰），但与DOC浓度不相关。放射性碳特征表明，Oa 层位下方的 DOC 主要源自 Oa 层位的吸留和矿物相关的有机质部分，而不是来自 Oi 或 Oe 层位。相对较老的 C 在 2006 年夏末干旱期后的再润湿阶段释放。相比之下，DO14C 特征表明在 2007 年整个潮湿年份释放了较年轻的 C。在 90 cm 深度的土壤溶液中，尽管 DOC 浓度持续较低，但 DO14C 特征也具有高度动态性（−127 ‰ 至 +3 ‰）。与 Oa 层类似，在 2006 年夏末的再润湿阶段之后，在 90 cm 深度处发现了最低的 DO14C 特征。由于该深度 DO14C 特征的变化，我们得出结论，DOC 并未与周围土壤平衡，而是源自覆盖土层。 DO14C 在径流和土壤溶液中的动态表明 DOC 的来源随时间变化很大。延长的干旱期可能会对相对古老且可能稳定的土壤有机质部分中 DOC 的释放和转移产生强烈影响。在校准基于 DO14C 特征的 DOC 模型时，需要考虑时间变化以及化石 DOC 的输入。
Dissolved organic carbon (DOC) is an important component of the C cycle in forest ecosystems, but dynamics and origin of DOC in throughfall and soil solution are yet poorly understood. In a 2-year study, we analyzed the radiocarbon signature of DOC in throughfall and soil solution beneath the Oa horizon and at 90 cm depth in a Norway spruce forest on a Podzol soil. A two-pool mixing model revealed that throughfall DOC comprised mainly biogenic C, i.e. recently fixed C, from canopy leaching and possibly other sources. The contribution of fossil DOC from atmospheric deposition to throughfall DOC was on average 6% with maxima of 8–11% during the dormant season. In soil solution from the Oa horizon, DO14C signature was highly dynamic (range from −8‰ to +103‰), but not correlated with DOC concentration. Radiocarbon signatures suggest that DOC beneath the Oa horizon originated mainly from occluded and mineral associated organic matter fractions of the Oa horizon rather than from the Oi or Oe horizon. Relatively old C was released in the rewetting phase following a drought period in the late summer of 2006. In contrast, the DO14C signature indicated the release of younger C throughout the humid year 2007. In soil solutions from 90 cm depth, DO14C signatures were also highly dynamic (−127‰ to +3‰) despite constantly low DOC concentrations. Similar to the Oa horizon, the lowest DO14C signature at 90 cm depth was found after the rewetting phase in the late summer of 2006. Because of the variation in the DO14C signatures at this depth, we conclude that DOC was not equilibrated with the surrounding soil, but also originated from overlaying soil horizons. The dynamics of DO14C in throughfall and soil solution suggest that the sources of DOC are highly variable in time. Extended drought periods likely have a strong influence on release and translocation of DOC from relatively old and possibly stabilized soil organic matter fractions. Temporal variations as well as the input of fossil DOC needs to be considered when calibrating DOC models based on DO14C signatures.