Atmospheric turbulence triggers pronounced diel pattern in karst carbonate geochemistry
Atmospheric turbulence triggers pronounced diel pattern in karst carbonate geochemistry
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DOI：
10.5194/bg-10-5009-2013
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发表时间：
2013-07
期刊：
影响因子：
4.9
通讯作者：
M. Roland;P. Serrano-Ortiz;A. Kowalski;Y. Goddéris;E. Sánchez‐Cañete;P. Ciais;F. Domingo;S. Cuezva;S. Sánchez-Moral;B. Longdoz;D. Yakir;R. Grieken;J. Schott;C. Cardell;I. Janssens
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文献类型：
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作者：
M. Roland;P. Serrano-Ortiz;A. Kowalski;Y. Goddéris;E. Sánchez‐Cañete;P. Ciais;F. Domingo;S. Cuezva;S. Sánchez-Moral;B. Longdoz;D. Yakir;R. Grieken;J. Schott;C. Cardell;I. Janssens
陆地生态系统与大气之间的CO2交换是理解气候变化与陆地表面之间反馈的关键。在含碳母质的地区，CO2交换模式的发生不能用生物过程来解释，例如在所有植被衰老期间白天或夜间CO2吸收的不成比例的释气。这两种现象都不能归因于碳酸盐风化反应，因为它们的CO2交换率太小。高大气湍流引起的土壤通风被发现可以解释碳质系统与大气之间的非典型CO2交换。然而，通过强烈改变地下CO2浓度，可以预期，风化作用会影响碳酸盐风化速率。通过在碳酸盐风化模型中施加通风驱动的CO2释气，我们在这里表明碳酸盐地球化学加速，并在半干旱生态系统的CO2交换模式中发挥了令人惊讶的重要作用。我们发现，通过在白天快速消耗土壤CO2，通风扰乱了土壤碳酸盐平衡，因此强烈放大了白天碳酸盐沉淀和相关的CO2产生。夜间，通风停止，耗尽的CO2浓度稳步上升。碳酸盐的溶解现在得到加强，这消耗了二氧化碳，并在很大程度上补偿了白天碳酸盐降水的增加。这就是为什么只有相对
CO2 exchange between terrestrial ecosystems and the atmosphere is key to understanding the feedbacks be- tween climate change and the land surface. In regions with carbonaceous parent material, CO2 exchange patterns oc- cur that cannot be explained by biological processes, such as disproportionate outgassing during the daytime or night- time CO2 uptake during periods when all vegetation is senes- cent. Neither of these phenomena can be attributed to car- bonate weathering reactions, since their CO2 exchange rates are too small. Soil ventilation induced by high atmospheric turbulence is found to explain atypical CO2 exchange be- tween carbonaceous systems and the atmosphere. However, by strongly altering subsurface CO2 concentrations, ventila- tion can be expected to influence carbonate weathering rates. By imposing ventilation-driven CO2 outgassing in a carbon- ate weathering model, we show here that carbonate geo- chemistry is accelerated and does play a surprisingly large role in the observed CO2 exchange pattern of a semi-arid ecosystem. We found that by rapidly depleting soil CO2 dur- ing the daytime, ventilation disturbs soil carbonate equilib- ria and therefore strongly magnifies daytime carbonate pre- cipitation and associated CO2 production. At night, venti- lation ceases and the depleted CO2 concentrations increase steadily. Dissolution of carbonate is now enhanced, which consumes CO2 and largely compensates for the enhanced daytime carbonate precipitation. This is why only a relatively