Stable Isotope Analysis Reveals Lower-Order River Dissolved Inorganic Carbon Pools Are Highly Dynamic

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• 作者：Susan Waldron ; E. Marian Scott ; Chris Soulsby
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：September 1, 2007
• 年：2007
• 卷：41
• 期：17
• 页码：6156 - 6162
• 全文大小：187K
• 年卷期：v.41,no.17(September 1, 2007)
• ISSN：1520-5851

文摘

River systems draining peaty catchments are considereda source of atmospheric CO₂, thus understanding the behaviorof the dissolved inorganic carbon pool (DIC) is valuable.The carbon isotopic composition, ¹³C_DIC, and concentration,[DIC], of fluvial samples collected diurnally, over 14months, reveal the DIC pools to be dynamic in range(-22 to -4.9”, 0.012 to 0.468 mmol L^-1 C), respondingpredictably to environmental influences such as changinghydrologic conditions or increased levels of primaryproduction. ¹⁸O of dissolved oxygen (DO) corroboratesthe ¹³C_DIC interpretation. A nested catchment samplingmatrix reveals that similar processes affect the DIC pool andthus ¹³C_DIC across catchment sizes. Not so with [DIC]:at high flow, the DIC export converges across catchmentsize, but at low flow catchments diverge in their DICload. Contextualizing ¹³C with discharge reveals thatorganic soil-waters and groundwaters comprise end-member sources, which in varying proportions constitutethe fluvial DIC pool. Discharge and pH describe well [DIC]and ¹³C_DIC, allowing carbon to be apportioned to each end-member from continuous profiles, demonstrated here for thehydrological year 2003-2004. This approach is powerfulfor assessing whether the dynamic response exhibited hereis ubiquitous in other fluvial systems at the terrestrial-aquatic interface or in larger catchments.