Carbon isotopes in the rivers from the Lesser Antilles: origin of the carbonic acid consumed by weathering reactions in the Lesser Antilles
Carbon isotopes in the rivers from the Lesser Antilles: origin of the carbonic acid consumed by weathering reactions in the Lesser Antilles
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DOI：
10.1002/esp.3385
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发表时间：
2013-07
影响因子：
3.3
通讯作者：
K. Rivé;J. Gaillardet;P. Agrinier;S. Rad
中科院分区：
文献类型：
--
作者：
K. Rivé;J. Gaillardet;P. Agrinier;S. Rad
在本文中，我们利用小安的列斯群岛火山弧（瓜德罗普岛、马提尼克岛和多米尼加岛）河流溶解负荷中的碳同位素来限制水-岩相互作用过程中中和反应中涉及的二氧化碳（CO2）的来源。 δ13C 数据的变化范围很大，对于 DIC（溶解无机碳）浓度范围为 11 μM 至 2000 μM 的情况，从 –19‰ 到 –5 · 2‰。与主要元素浓度相结合，碳同位素比率被解释为反映了岩浆CO2（富含重碳（δ13C ≈ –3·5‰）和土壤中产生的生物CO2（富含轻碳（δ13C < –17‰））的混合物。碳同位素表明，在区域尺度上，风化反应消耗的CO2中有23%至40%来自岩浆，并转移到河流系统中这些数字仍然是一阶估计，因为使用碳同位素作为源示踪剂的主要不确定性是，碳同位素可以通过许多过程进行分馏，包括土壤和河流脱气，无论是在热液（热）还是地表（冷）风化条件下，化学风化至少部分受到岩浆二氧化碳输入的控制。
In this paper, we use carbon isotopes in the dissolved load of rivers from the Lesser Antilles volcanic arc (Guadeloupe, Martinique and Dominica islands) to constrain the source of the carbon dioxide (CO2) involved in the neutralization reactions during water–rock interactions. The δ13C data span a large range of variations, from –19‰ to –5 · 2‰ for DIC (dissolved inorganic carbon) concentrations ranging from 11 μM to 2000 μM. Coupled with major element concentrations, carbon isotopic ratios are interpreted as reflecting a mixture of magmatic CO2 (enriched in heavy carbon (δ13C ≈ –3 · 5‰) and biogenic CO2 produced in soils (enriched in light carbon (δ13C < –17‰)). Carbon isotopes show that, at the regional scale, 23 to 40% of CO2 consumed by weathering reactions is of magmatic origin and is transferred to the river system through aquifers under various thermal regimes. These numbers remain first‐order estimates as the major uncertainty in using carbon isotopes as a source tracer is that carbon isotopes can be fractionated by a number of processes, including soil and river degassing. Chemical weathering is clearly, at least, partly controlled by the input of magmatic CO2, either under hydrothermal (hot) or surficial (cold) weathering regimes.