A reactive transport approach to modeling cave seepage water chemistry I: Carbon isotope transformations
A reactive transport approach to modeling cave seepage water chemistry I: Carbon isotope transformations
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模拟洞穴渗流水化学的反应输运方法 I：碳同位素变换
DOI：
10.1016/j.gca.2021.06.041
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发表时间：
2021
影响因子：
5
通讯作者：
Oster, Jessica L.
中科院分区：
文献类型：
--
作者：
Druhan, Jennifer L.;Lawrence, Corey R.;Covey, Aaron K.;Giannetta, Max G.;Oster, Jessica L.
大多数关键区研究都强调硅酸盐岩性，其特点是反应速率相对较慢和风化不一致。然而，以碳酸盐为主的岩性相对简单的风化作用可能会产生次生矿床，例如洞穴，为关键带过程提供长期档案。特别是，洞穴中的碳同位素变异性有可能提供植被、土壤呼吸、深层土壤碳稳定性和/或主岩化学风化变化的记录。尽管有机会重建许多关键区域过程，但多重影响也可能使这些洞穴碳同位素记录的解释变得具有挑战性。喀斯特系统特有的观测数据和模拟的整合为碳酸盐景观演化过程中积累的这些独特的时间平均记录提供了解释框架。在这里，我们基于对美国田纳西州中部蓝泉洞穴的多年监测研究，提出了基于过程的正向反应输运模拟。该模拟描述了石灰石的流体驱动风化，包括根据通过实验室批量反应数据校准的反应速率对溶解钙、稳定碳和放射性碳同位素比率进行明确跟踪。我们发现，钙浓度和放射性碳同位素比受到流体流速和土壤二氧化碳含量组合的强烈影响，并且需要上覆土壤边界条件和内部喀斯特之间的快速气相连通，以维持较高的石灰岩风化速率和相对现代的放射性碳特征。稳定碳同位素很大程度上取决于同时期物种之间依赖于温度的平衡分馏。这些模拟扩展到广泛的参数空间，以证明这些同位素代理记录的环境因素。
The majority of Critical Zone research has emphasized silicate lithologies, which are typified by relatively slow rates of reactivity and incongruent weathering. However, the relatively simpler weathering of carbonate-dominated lithology can result in secondary mineral deposits, such as speleothems, which provide a long-term archive for Critical Zone processes. In particular, carbon isotopic variability in speleothems has the potential to provide records of changes in vegetation, soil respiration, carbon stabilization in deep soils, and/or chemical weathering in the host rock. Despite this opportunity to reconstruct many Critical Zone processes, multiple influences can also make interpretion of these speleothem carbon isotope records challenging. The integration of observational data and simulations specific to karst systems offers an interpretive framework for these unique time-averaged records accumulated through the evolution of carbonate landscapes. Here, we present a forward and process-based reactive transport simulation based on a multi-year monitoring study of Blue Spring Cave in central Tennessee, USA. The simulations describe the fluid-driven weathering of limestone including explicit tracking of dissolved calcium, stable carbon, and radiocarbon isotope ratios based on reaction rates calibrated through laboratory batch reaction data. We find that calcium concentrations and radiocarbon isotope ratios are strongly influenced by the combination of fluid flow rate and soil CO2content, and require rapid gas phase communication between the overlying soil boundary condition and interior karst to sustain both elevated limestone weathering rates and relatively modern radiocarbon signatures. Stable carbon isotopes are largely dictated by temperature-dependent equilibrium fractionation among contemporaneous species. These simulations are extended to a wide range of parameter space to demonstrate the environmental factors that these isotope proxies record.
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影响因子：
4
作者：
Corinne I. Wong;J. Banner;M. Musgrove
通讯作者：
Corinne I. Wong;J. Banner;M. Musgrove
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影响因子：
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作者：
P. Carlson;J. Banner;K. Johnson;R. Casteel;D. Breecker
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影响因子：
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作者：
J. Oster;A. Covey;C. Lawrence;M. Giannetta;J. Druhan
通讯作者：
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影响因子：
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作者：
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通讯作者：
POLACH, HA
影响因子：
4.5
作者：
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通讯作者：
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