Assessing the nonconservative fluvial fluxes of dissolved organic carbon in North America
Assessing the nonconservative fluvial fluxes of dissolved organic carbon in North America
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DOI：
10.1029/2011jg001820
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发表时间：
2012-03-03
影响因子：
3.7
通讯作者：
Moosdorf, Nils
中科院分区：
文献类型：
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作者：
Lauerwald, Ronny;Hartmann, Jens;Moosdorf, Nils
溶解有机碳（DOC）的河流输运是全球碳循环的重要环节。以前的研究在很大程度上增加了我们对河流向海洋系统输出碳的认识，但关于有机碳的流/河损失仍然存在相当大的不确定性。本研究提供了一个经验方法来评估在大陆尺度上的河流DOC的非保守行为。在两个不同的训练集水区子集上训练经验DOC通量模型，一个集水区小于2,000 km（2）（n = 246，平均值）。494 km（2））和一个集水区大于2，000 km（2）（n = 207，avg. 26，525公里（2））。各种潜在的预测和河流DOC通量的控制因素进行了讨论。最终DOC通量模型保留的预测径流，坡度，土地覆盖，湿地面积比例。根据模型的空间外推，在北美60 ° N以南，来自小流域的总河流DOC通量（25.8 Mt C a（-1），标准差）。错误：12%）高于大流域（19.9Mt C a（-1），std.错误：10%），总DOC损失为5.9 Mt C a（-1）（标准。错误：78%）。由于本预算中未列出上游DOC损失，因此估算的DOC损失是河流网络内总DOC损失的最小值。
Fluvial transport of dissolved organic carbon (DOC) is an important link in the global carbon cycle. Previous studies largely increased our knowledge of fluvial exports of carbon to the marine system, but considerable uncertainty remains about in-stream/in-river losses of organic carbon. This study presents an empirical method to assess the nonconservative behavior of fluvial DOC at continental scale. An empirical DOC flux model was trained on two different subsets of training catchments, one with catchments smaller than 2,000 km(2) (n = 246, avg. 494 km(2)) and one with catchments larger than 2,000 km(2) (n = 207, avg. 26,525 km(2)). A variety of potential predictors and controlling factors of fluvial DOC fluxes is discussed. The predictors retained for the final DOC flux models are runoff, slope gradient, land cover, and areal proportions of wetlands. According to the spatially explicit extrapolation of the models, in North America south of 60 degrees N, the total fluvial DOC flux from small catchments (25.8 Mt C a(-1), std. err.: 12%) is higher than that from large catchments (19.9 Mt C a(-1), std. err.: 10%), giving a total DOC loss of 5.9 Mt C a(-1) (std. err.: 78%). As DOC losses in headwaters are not represented in this budget, the estimated DOC loss is rather a minimum value for the total DOC loss within the fluvial network.