Riverine carbon dioxide evasion along a high-relief watercourse derived from seasonal dynamics of the water-atmosphere gas exchange.
Riverine carbon dioxide evasion along a high-relief watercourse derived from seasonal dynamics of the water-atmosphere gas exchange.
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DOI：
10.1016/j.scitotenv.2018.12.158
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发表时间：
2019-03
期刊：
影响因子：
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通讯作者：
T. Juhlke;R. van Geldern;F. Huneau;É. Garel;S. Santoni;H. Hemmerle;J. Barth
中科院分区：
文献类型：
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作者：
T. Juhlke;R. van Geldern;F. Huneau;É. Garel;S. Santoni;H. Hemmerle;J. Barth
对法国科西嘉岛塔维格纳努河(Tavignanu River，法国科西嘉岛)高地势集水区的河流碳收支和稳定碳同位素进行了研究。该流域的海拔范围为2622 m。河流溶解无机碳(DIC或TCO2)的主要来源取决于季节和次流域岩性。冬季δ-2~−-7-−-‰的13CDIC值反映了大气CO_2的影响，δ-13CDIC值在7月份逐渐下降到−-9-−-12‰之间，表明土壤对CO_2的贡献增加。观测到的下游碳物种总量的增加与夏季含碳酸盐支流的输入和蒸发效应有关。主航道二氧化碳分压(PCO2)在上硅酸盐集水区和下沿海平原具有很高的季节性变化，那里的夏季值超过了大气水平的6倍。在冬季，塔维格纳努河的中部被发现在大气二氧化碳水平方面是不饱和的。主通道pCO2的中位数冬春季低于大气水平，夏秋季高于大气水平。用(0.77 ± 0.24)GG C yr−1计算了塔维纳努河跨气水边界的年碳通量，约为河流向海洋输送的0 11 GG C yr−1的7倍。虽然塔维纳努河的大部分河段经历了全年大气CO2的吸收或平衡，但作为一个整体，河流是一个少量但持续的大气碳净来源。这突显了较小的溪流和河流对陆地碳通量的重要贡献，以及将其纳入未来全球碳循环模型的必要性，但到目前为止还没有受到很好的限制。
The high-relief catchment of the Tavignanu River (Corsica Island, France) with an elevation range from sea level to 2622 m above sea level was investigated for its riverine carbon budget and stable carbon isotopes. Major riverine dissolved inorganic carbon (DIC or TCO2) sources depended on seasons and sub-catchment lithology. In winterδ13CDICvalues of −2 to −7‰ (VPDB) indicated influences of atmospheric CO2.δ13CDICvalues decreased gradually to values between −9 and −12‰ in July, which indicates elevated soil CO2contribution. An observed downstream increase in the total amount of carbon species correlated with inputs from carbonate bearing tributaries and evaporation effects in summer. Main channel partial pressure of CO2(pCO2) was seasonally highly variable in the upper silicate catchment and the lower coastal plain, where summer values exceed up to six times atmospheric levels. During winter, the central section of the Tavignanu River was found to be undersaturated with respect to atmospheric CO2levels. The median values for main channelpCO2were below atmospheric levels in winter and spring and above in summer and autumn. The annual carbon flux across the air-water boundary (FCO2) along the Tavignanu River was calculated with (0.77 ± 0.24) Gg C yr−1, which is about seven times higher than the riverine TCO2transport to the sea of about 0.11 Gg C yr−1. While large sections of the river experienced year-round atmospheric CO2uptake or equilibrium, the river as a whole was a small but continuous net source of carbon to the atmosphere. This underlines the important, but so far not well-constrained, contributions of smaller streams and rivers to the terrestrial carbon flux and the need of incorporating them into future global carbon cycle models.