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The burial of organic carbon (OC) preserves paleoenvironmental archives and drives the evolution of Earth's biogeochemical cycles. While the impact of kinetic heterogeneity on OC preservation has been studied, the effects of sedimentation dynamics remain largely unknown. Here, we incorporate the expected stochastic variability in sedimentation rates into a reactive‐transport model, generate predictions for stratigraphic variability of OC burial efficiency, and compare the model outputs to field observations. We find that internal sedimentation dynamics profoundly influence OC preservation efficiencies and create autogenic signals that may obscure signals originated from external forcings. Simulations match observations in terms of power spectra when our model considers transient periods of erosion during net deposition, implying that the manifestation of sedimentation dynamics and their interactions with biogeochemistry in chemostratigraphic records are prevalent in nature. As sedimentary OC records reflect both internal variability and external forcing, they may be used as proxies for past depositional conditions. Plain Language Summary: In regions of sediment accumulation, the rates of deposition can vary in space and time even when factors like climatic conditions are kept constant. This type of "random" variability complicates the interpretation of the geologic record because many important chemical signals are affected by changes in sediment deposition rates. To explore the specific effects of random variability, we constructed a model with realistic, time‐varying sedimentation rates that tracks the burial and oxidation of organic matter. We chose organic matter because it is important to the global carbon cycle and is also commonly used to infer past environmental changes. We find that random changes in sedimentation rates can meaningfully impact organic matter burial and create patterns that look conspicuously like field observations interpreted as reflecting changes in environmental conditions. By predicting the patterns that can form randomly, our approach can help improve the interpretations of the geologic record. Key Points: Complex dynamics in sedimentation can profoundly influence organic carbon (OC) preservation efficiency, which has been largely overlookedAutogenic signals in OC burial can arise from sedimentation dynamics and may obscure signals originated from external forcingModel‐data comparison suggests the manifestation of sedimentation dynamics in chemostratigraphic records are prevalent in nature [ABSTRACT FROM AUTHOR]

The degradation and loss of ecologically important wetlands has been a topical issue in the Great Lakes region, where 60–80% of the coastal wetlands have been lost since the 1800s. The present modeling study aims to guide the restoration efforts in Cootes Paradise marsh, one of the most degraded shallow wetlands in Southern Ontario. We use a process‐based eutrophication model designed to reproduce the biotic competition among multiple phytoplankton and macrophyte functional groups. Our primary focus is to offer guidelines for wetland restoration by characterizing the ecophysiological processes of the autotrophic assemblage, such as the nutrient uptake from the water column and/or the sediment pore waters, the relative ability to harvest light and fuel photosynthesis, and temperature control of the algal/macrophyte growth and basal metabolism. We predict that the additional reduction of external phosphorus loading in Cootes Paradise could induce an abrupt, non‐linear shift from the current turbid phytoplankton‐dominated state to a desirable clear macrophyte‐dominated state. The emergence of this critical (or tipping) point, where the shift to another ecological state may occur, can be accelerated by the presence of a thriving macrophyte community with an enhanced ability to sequester phosphorus. However, it may also be delayed by the presence of a suite of biogeochemical mechanisms (often referred to as "feedback loops"), such as the remobilization of legacy P due to sediment diagenetic processes, wind resuspension, bioturbation, hydraulic loading from local tributaries, water‐level fluctuations, and the leachable P pool of dead plant material that can be returned into the water column through senescence. Our study identifies the restoration actions required to minimize the likelihood of prolonged hysteresis and to facilitate a shift to a desirable ecological state in the foreseeable future. The areal expansion of aquatic vegetation will not only lead to the establishment of a thriving meadow and emergent vegetation community, but may also pave the way for submerged macrophytes through a suite of synergistic mechanisms. Additional point‐source loading reductions will facilitate the transition to an alternative stable clear macrophyte‐dominated state, but could also consolidate the future resilience of the marsh. [ABSTRACT FROM AUTHOR]

This paper presents the results of geoarchaeological and geochronological investigations at Con Moong Cave, North Vietnam. Beneath the published, terminal Pleistocene sequence, recent excavations have uncovered a ~5 m stratigraphic sequence containing flaked stone artifacts and sedimentary features that indicate extensive post‐depositional change. As the effects of tropical conditions on Pleistocene cave sediments are poorly resolved, a range of complementary techniques was selected to reconstruct the nature of on‐site sedimentation and occupation, while assessing the taphonomy of archaeological and palaeoecological materials. Our approach incorporates microstratigraphic, geochemical and sedimentological analyses, using optically stimulated luminescence (OSL) dating to estimate the time of sediment deposition in the cave. This case study has broad application to tropical zones worldwide. Sedimentation began in early Marine Isotope Stage (MIS) 4, while micromorphologically observed human occupation commenced before 42 thousand years ago (ka). By placing our results within the context of published, high‐resolution regional records of climate, we demonstrate that on‐site rhythms of Pleistocene occupation correlated with environmental changes in the region. During MIS 3, episodic abandonment of the site coincided with periods of drier conditions, while rapid climate fluctuations in MIS 2 corresponded with short‐lived occupation events and a switch to predominantly geogenic deposition in the cave. [ABSTRACT FROM AUTHOR]