The coastal terrestrial-aquatic interface (TAI) is a highly dynamic system characterized by strong physical, chemical, and biological gradients. In particular, shifting soil redox conditions and consumption of terminal electron acceptors, due in part to dynamic hydrologic conditions, is a strong driver of carbon availability and transformations across TAIs. However, while redox dynamics are well described, our ability to quantitatively forecast rates ofoxic to anoxic shifts in soils with different characteristics and inundation regimes is limited. We integrated field measurements, laboratory incubations, and model simulations to improve mechanistic understanding of oxygen consumption dynamics in coastal soils. Continuous in situ monitoring unexpectedly revealed that flooding caused temporary spikes in subsurface dissolved oxygen followed by rapid consumption in the wetlands. To further investigate these mechanisms in a controlled setting, we performed laboratory incubations using surface and subsurface soils from a TAI gradient (defined here as upland forest to transitional forest to wetland) in Western Lake Erie to measure oxygen consumption rates in TAI soils during flood events. In our experiments, wetland soils reached anoxia the fastest, in ∼ 9 h on average, whereas upland soils turned anoxic in ∼ 18 h. Subsurface upland soils did not turn anoxic even after two weeks of saturation in the lab, and their oxygen consumption patterns suggested carbon and/or nutrient limitation. These results are consistent with in-situ groundwater redox and oxygen measurements in the field, where wetland soils exhibited the highest rates of oxygen consumption along the TAI. Model simulations of oxygen consumption suggested that oxygen consumption had stronger abiotic controls in wetland soils but stronger biotic controls in upland soils, providing a useful framework for future incubation experiments. Microbial activity is a strong driver of oxygen consumption in TAI soils, although it is constrained by the availability of dissolved carbon in subsurface soils.

中文翻译：

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缺氧时间：沿海洪水事件后氧气下降的观察和预测

沿海陆地-水界面（TAI）是一个高度动态的系统，其特征是强烈的物理、化学和生物梯度。特别是，土壤氧化还原条件的变化和末端电子受体的消耗（部分归因于动态水文条件）是跨 TAI 碳可用性和转化的强大驱动力。然而，虽然氧化还原动力学得到了很好的描述，但我们定量预测具有不同特征和淹没状况的土壤中缺氧到缺氧转变速率的能力是有限的。我们整合了现场测量、实验室孵化和模型模拟，以提高对沿海土壤耗氧动态的机械理解。连续的现场监测意外地发现，洪水导致地下溶解氧暂时激增，随后湿地迅速消耗。为了在受控环境中进一步研究这些机制，我们使用伊利湖西部 TAI 梯度（此处定义为高地森林到过渡森林到湿地）的表层和地下土壤进行实验室培养，以测量洪水事件期间 TAI 土壤的耗氧率。在我们的实验中，湿地土壤达到缺氧最快，平均需要 9 小时，而旱地土壤则在 18 小时内变成缺氧。即使在实验室饱和两周后，地下高地土壤也不会变得缺氧，它们的耗氧模式表明碳和/或养分的限制。这些结果与现场地下水氧化还原和氧气测量结果一致，其中湿地土壤在 TAI 沿线表现出最高的耗氧率。耗氧量的模型模拟表明，耗氧量在湿地土壤中具有更强的非生物控制作用，但在高地土壤中具有更强的生物控制作用，这为未来的孵化实验提供了有用的框架。微生物活动是 TAI 土壤中氧消耗的强大驱动力，尽管它受到地下土壤中溶解碳的可用性的限制。