Landscape‐level controls on dissolved carbon flux from diverse catchments of the circumboreal
Landscape‐level controls on dissolved carbon flux from diverse catchments of the circumboreal
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DOI：
10.1029/2012gb004299
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发表时间：
2012-12
影响因子：
5.2
通讯作者：
S. Tank;K. Frey;R. Striegl;P. Raymond;R. Holmes;J. McClelland;B. Peterson
中科院分区：
文献类型：
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作者：
S. Tank;K. Frey;R. Striegl;P. Raymond;R. Holmes;J. McClelland;B. Peterson
虽然河流中大部分溶解的有机碳 (DOC) 注定要矿化为 CO2，但河流碳酸氢盐 (HCO3−) 通量的很大一部分代表了 CO2 汇，这是风化过程将 CO2 封存为 HCO3− 的结果。我们探索了景观层面对北方流域子流域 DOC 和 HCO3− 通量的控制，特别关注永久冻土对河流溶解碳通量的影响。为此，我们进行了多变量分析，在检查永久冻土的影响之前，使用来自环北带麦肯齐、育空地区、东西伯利亚地区的一系列子流域的河流生物地球化学数据，划分了溶解碳通量（径流、岩性和植被）的已知关键调节因素的方差。在我们研究的不同流域中，对 HCO3− 通量的控制几乎是普遍的：径流和碳酸盐岩对风化作用的增加（评估为河水 Ca:Na）增加了 HCO3− 产量，而永久冻土范围的增加与 HCO3− 的减少有关。相比之下，即使在考虑了其通量的其他关键驱动因素引起的变化之后，永久冻土对 DOC 产量也具有对比性和区域特异性的影响。我们使用离子比率和 SO4 产量来计算这些北方子流域通过风化封存的 CO2 的潜在范围，并表明，永久冻土范围的减少与广泛空间尺度上风化介导的 CO2 固定的增加有关，这种效应可以抵消随着永久冻土减少而预测的一些有机碳矿化。
While much of the dissolved organic carbon (DOC) within rivers is destined for mineralization to CO2, a substantial fraction of riverine bicarbonate (HCO3−) flux represents a CO2 sink, as a result of weathering processes that sequester CO2 as HCO3−. We explored landscape‐level controls on DOC and HCO3− flux in subcatchments of the boreal, with a specific focus on the effect of permafrost on riverine dissolved C flux. To do this, we undertook a multivariate analysis that partitioned the variance attributable to known, key regulators of dissolved C flux (runoff, lithology, and vegetation) prior to examining the effect of permafrost, using riverine biogeochemistry data from a suite of subcatchments drawn from the Mackenzie, Yukon, East, and West Siberian regions of the circumboreal. Across the diverse catchments that we study, controls on HCO3−flux were near‐universal: runoff and an increased carbonate rock contribution to weathering (assessed as riverwater Ca:Na) increased HCO3− yields, while increasing permafrost extent was associated with decreases in HCO3−. In contrast, permafrost had contrasting and region‐specific effects on DOC yield, even after the variation caused by other key drivers of its flux had been accounted for. We used ionic ratios and SO4 yields to calculate the potential range of CO2sequestered via weathering across these boreal subcatchments, and show that decreasing permafrost extent is associated with increases in weathering‐mediated CO2 fixation across broad spatial scales, an effect that could counterbalance some of the organic C mineralization that is predicted with declining permafrost.