Southeast Environmental Research Center, Florida International University, Miami, FL, USA; Department of Chemistry & Biochemistry, Florida International University, Miami, FL, USA.
Faculty of Environmental Earth Science, Hokkaido University, Hokkaido, Japan.
Chemosphere. 2013 Mar;90(10):2557-62. doi: 10.1016/j.chemosphere.2012.10.098. Epub 2012 Dec 4.
While the existence of black carbon as part of dissolved organic matter (DOM) has been confirmed, quantitative determinations of dissolved black carbon (DBC) in freshwater ecosystem and information on factors controlling its concentration are scarce. In this study, stream surface water samples from a series of watersheds subject to different burn frequencies in Konza Prairie (Kansas, USA) were collected in order to determine if recent fire history has a noticeable effect on DBC concentration. The DBC levels detected ranged from 0.04 to 0.11 mg L(-1), accounting for ca. 3.32±0.51% of dissolved organic carbon (DOC). No correlation was found between DBC concentration and neither fire frequency nor time since last burn. We suggest that limited DBC flux is related to high burning efficiency, possibly greater export during periods of high discharge and/or the continuous export of DBC over long time scales. A linear correlation between DOC and DBC concentrations was observed, suggesting the export mechanisms determining DOC and DBC concentrations are likely coupled. The potential influence of fire history was less than the influence of other factors controlling the DOC and DBC dynamics in this ecosystem. Assuming similar conditions and processes apply in grasslands elsewhere, extrapolation to a global scale would suggest a global grasslands flux of DBC on the order of 0.14 Mt carbon year(-1).
尽管已经证实了黑碳作为溶解有机物 (DOM) 的一部分的存在，但在淡水生态系统中定量测定溶解黑碳 (DBC) 的方法以及控制其浓度的因素信息却很少。在这项研究中，从堪萨斯州康萨草原（Konza Prairie）一系列受到不同火烧频率影响的流域中采集了地表河水样本，以确定近期的火灾历史是否对 DBC 浓度有明显影响。检测到的 DBC 水平范围为 0.04 至 0.11mg/L，占溶解有机碳 (DOC) 的约 3.32±0.51%。DBC 浓度与火烧频率或上次火烧以来的时间均无相关性。我们认为，有限的 DBC 通量与高燃烧效率有关，可能在高流量期间有更多的 DBC 输出，或者在长时间尺度上持续输出 DBC。DOC 和 DBC 浓度之间观察到线性相关性，这表明决定 DOC 和 DBC 浓度的输出机制可能是耦合的。在这个生态系统中，火烧历史的潜在影响小于控制 DOC 和 DBC 动态的其他因素的影响。假设类似的条件和过程适用于其他草原地区，那么推断全球尺度上的全球草原 DBC 通量约为 0.14Mt 碳年(-1)。
