Periodic Changes Research Articles

Structure evolution of the silica glass under the vibration field through molecular dynamics simulations

AbstractSilica glass has found wide applications, including space shuttle windows, optical fibers, and deep ultraviolet light lens elements, due to its excellent optical, electrical, and mechanical properties. However, understandings of its structure change under the vibration field are limited in literature. In this work, the structure of silica glass and its behavior under the vibration field have been investigated through molecular dynamics simulations. The short and medium‐range structures, including coordination number, Qn species distribution, pair distribution function, and bond angle distribution, were analyzed. It was found that the overall and local structures of silica glass showed periodic changes under the vibration field. The root‐mean‐square displacements as well as the kinetic energies of the atoms in the system were further analyzed. The results show that there is a periodic transformation of kinetic and potential energies. In addition, the kinetic energy decreases and is converted into the thermal energy during the vibration, which is confirmed by the increase of the system temperature. This can explain the thermoelastic loss mechanism in energy dissipation from literature. This work reveals the structure evolution and energy change of glass under the vibration field from atomistic level, which provides important understandings for related researches.

Prevalence and factors associated with poor sleep quality among nurses in COVID-19 wards

The COVID-19 pandemic has significantly impacted the working conditions of nurses, leading to a detrimental effect on their sleep quality. This cross-sectional study aimed to investigate the prevalence of poor sleep quality and its associated factors among nurses working in COVID-19 wards in Kermanshah, Iran. A total of 97 nurses were selected through simple random sampling from COVID-19 wards. Data was collected using a demographic information sheet and the Pittsburgh Sleep Quality Index. Descriptive and inferential statistical methods, including chi-square and multiple logistic regression, were used for data analysis. The results showed that 74.2% (n = 72) of the nurses experienced poor sleep quality. Significant associations were found between poor sleep quality and work experience (p = 0.045) as well as the type of work shift (p = 0.001). However, no significant relationships were observed between poor sleep quality and factors such as age, sex, body mass index, overtime hours per month, physical activity, or underlying diseases. The high prevalence of poor sleep quality among nurses working in COVID-19 wards underscores the necessity of implementing targeted interventions to address this issue. In this regard, in addition to periodic shift schedule changes and reductions in working hours, it is necessary to adopt purposeful measures to improve working conditions and enhance the physical and mental health of nurses. These measures may include providing sufficient human resources to reduce the workload and fatigue of nurses, appropriate scheduling of working hours, and the implementation of stress management programs.

Possible criticality scenario and its mechanism of the Windscale Works criticality accident in 1970 analyzed by computational fluid dynamics and Monte Carlo neutron transport

The Windscale Works criticality accident in 1970 resulted from mixing an aqueous solution with an organic solvent with different plutonium concentrations and densities. Although this accident has been studied using improved computer capabilities in recent years, a precise criticality scenario has not yet been identified. This study aims to clarify a possible criticality scenario of the accident—the time variation of reactivity and its mechanism. The accident was simulated by combining the multiphase computational fluid dynamics solver of OpenFOAM and the delta-tracking-based Monte Carlo neutron transport code Serpent2. Consequently, the periodic uneven arrangement of fluids might have caused oscillations in neutron leakage and absorption, resulting in periodic wavy reactivity changes. Furthermore, the emulsion, which was thought to be the primary cause, might not be the dominant mechanism for reactivity change, although it contributed to the criticality of the accident.

Effect of high-intensity vibration parameter on droplet transport characteristics in gas channel of proton exchange membrane fuel cell

In aerospace applications, proton exchange membrane fuel cells are subject to high-intensity vibration. Vibration has a substantial effect on water transport in fuel cells. However, there is a lack of research on the effects of multi-directional and high-intensity vibration conditions on fuel cells. In this study, the droplet transport characteristics in the gas channel under high-intensity vibration conditions are investigated for the first time. Moreover, the effects of vibration direction and vibration frequency on the droplet dynamic transport process are specifically studied. The droplet transport state, drainage performance, and pressure drop variation in the gas channel under different vibration conditions are analyzed and interpreted. The results show that low-frequency vibration in the longitudinal direction is more conducive to the droplet discharge, and the pressure drop undergoes a periodic change corresponding to the vibration frequency. Vertical vibration promotes droplet detachment from the gas diffusion layer surface, which contributes to the reduction in water coverage ratio on its surface, despite an increase in the channel pressure drop. Under the influence of horizontal vibration, droplets are more susceptible to adsorption on the channel sidewalls and turn into a liquid film, which leads to a longer discharge time and a reduction in pressure drop.

Morphodynamics of the dredged channel in a mega fluvial-tidal delta

Deltaic channels are key pathways connecting rivers and the ocean, which is of significance for in maintaining estuarine stability and material transport processes between land and sea. However, deltaic channels have experienced dramatic variations in the Anthropocene era, including seriously scouring induced by decline of riverine sediment delivered to the ocean, trenching caused by dredged works and episodic filling by storm events. Here, a series of hydrology, sediment as well as elevation data between 1979 and 2020 of North Passage (NP), one of most important navigated channels over the Changjiang Estuary Delta, were used to analyze its long-term morphodynamic processes. Results show that during 1979–2020, NP capacity presented stage changes: gentle increase stage between 1979 and 1997, fluctuation stage between 1997 and 2002, fast-descend stage between 2002 and 2007, slow growth stage between 2007 and 2020, and periodic signals of 13 and 25 months can be detected in NP volume. Meanwhile, the shoal zone and the deep channel showed long-term decrease and increase trend respectively, making NP turn into a narrow and deep deltaic channel. Moreover, NP exhibited two major morphodynamic patterns. The first mode indicates the long-term continuous erosion of the main-channel region and persistent deposition in the groin region. The second mode explains the transition of the erosion/deposition state of NP, where the huge mouth bar system in NP was shifted seaward accompanied by a decrease of its extent. The periodic changes of fluvial water and sediment may contribute the oscillation of erosion and accretion process of NP. The construction of engineering structures and long-term dredging works resulted in constant deposition in the groin region with continuous erosion in main-channel region. The existence of estuarine turbidity maximum was conductive to deposition in the main-channel region.

Study on cavitation and pulsation characteristics of a novel rotor-radial groove hydrodynamic cavitation reactor

Abstract Hydrodynamic cavitation is widely used in many fields such as water treatment, impact rock breaking, and food preparation. The performance of hydrodynamic cavitation is closely related to its internal flow field. In the present study, cavitation flow field was analyzed by computational fluid dynamics in the reactor. The cavitation performance of the rotor is evaluated under different operating conditions. The time frequency distribution of pressure pulsation is studied. The pressure increases at the connection point between the local low-pressure area and the mainstream low-pressure area. Cavitation bubbles collapsed at the tail end of the cavity to form a local void area. The blade frequency amplitude of pressure pulsation shows the significant periodic change. The blade frequency amplitude decreases along the flow direction. The effect of the fluid outlet led to the increase in the second-order harmonic frequency amplitude. The research results could provide theoretical support for the research of cavitation mechanism of cavitation equipment.

Tailored micromixing in chemically patterned microchannels undergoing electromagnetohydrodynamic flow.

The study unveils a simple, non-invasive method to perform micromixing with the help of spatiotemporal variation in the Lorentz force inside a microchannel decorated with chemically heterogeneous walls. Computational fluid dynamics simulations have been utilized to investigate micromixing under the coupled influence of electric and magnetic fields, namely, electromagnetohydrodynamics, to alter the direction of the Lorentz force at the specific locations by creating the reverse flow zones where the pressure gradient, . The study explores the impact of periodicity, distribution, and size of electrodes alongside the magnitude of applied field intensity, the flow rate of the fluid, and the nature of the electric field on the generation of the mixing vortices and their strength inside the microchannels. The results illustrate that the wall heterogeneities can indeed enforce the formation of localized on-demand vortices when the strength of the localized reverse flow overcomes the inertia of the mainstream flow. In such a scenario, while the vortex size and strength are found to increase with the size of the heterogeneous electrodes and field intensities, the number of vortices increases with the number of heterogeneous electrodes decorated on the channel wall. The presence of a non-zero pressure-driven inflow velocity is found to subdue the strength of the vortices to restrict the mixing facilitated by the localized variation of the Lorentz force. Interestingly, the usage of an alternating current (AC) electric field is found to provide an additional non-invasive control on the mixing vortices by enabling periodic changes in their direction of rotation. A case study in this regard discloses the possibility of rapid mixing with the usage of an AC electric field for a pair of miscible fluids inside a microchannel.

Mapping “Brain Terrain” Regions on Mars Using Deep Learning

One of the main objectives of the Mars Exploration Program is to search for evidence of past or current life on the planet. To achieve this, Mars exploration has been focusing on regions that may have liquid or frozen water. A set of critical areas may have seen cycles of ice thawing in the relatively recent past in response to periodic changes in the obliquity of Mars. In this work, we use convolutional neural networks to detect surface regions containing “brain terrain,” a landform on Mars whose similarity in morphology and scale to sorted stone circles on Earth suggests that it may have formed as a consequence of freeze/thaw cycles. We use large images (∼100–1000 megapixels) from the Mars Reconnaissance Orbiter to search for these landforms at resolutions close to a few tens of centimeters per pixel (∼25–50 cm). Over 58,000 images (∼28 TB) were searched (∼5% of the Martian surface), and we found detections in 201 images. To expedite the processing, we leverage a classifier network (prior to segmentation) in the Fourier domain that can take advantage of JPEG compression by leveraging blocks of coefficients from a discrete cosine transform in lieu of decoding the entire image at the full spatial resolution. The hybrid pipeline approach maintains ∼93% accuracy while cutting down on ∼95% of the total processing time compared to running the segmentation network at the full resolution on every image.

Modelling Lassa virus dynamics in West African Mastomys natalensis and the impact of human activities.

Lassa fever is a West African rodent-borne viral haemorrhagic fever that kills thousands of people a year, with 100 000 to 300 000 people a year probably infected by Lassa virus (LASV). The main reservoir of LASV is the Natal multimammate mouse, Mastomys natalensis. There is reported asynchrony between peak infection in the rodent population and peak Lassa fever risk among people, probably owing to differing seasonal contact rates. Here, we developed a susceptible-infected-recovered ([Formula: see text])-based model of LASV dynamics in its rodent host, M. natalensis, with a persistently infected class and seasonal birthing to test the impact of changes to seasonal birthing in the future owing to climate and land use change. Our simulations suggest shifting rodent birthing timing and synchrony will alter the peak of viral prevalence, changing risk to people, with viral dynamics mainly stable in adults and varying in the young, but with more infected individuals. We calculate the time-average basic reproductive number, [Formula: see text], for this infectious disease system with periodic changes to population sizes owing to birthing using a time-average method and with a sensitivity analysis show four key parameters: carrying capacity, adult mortality, the transmission parameter among adults and additional disease-induced mortality impact the maintenance of LASV in M. natalensis most, with carrying capacity and adult mortality potentially changeable owing to human activities and interventions.

Analyzing Google Search Trends for Migraine Surgery and Nurtec in Response to Public Announcements.

Nurtec, a versatile migraine medication, has gained popularity. However, the awareness of migraine surgery remains uncertain. Following a descriptive approach, this cross-sectional study used Google Trends data as of December 1, 2023, to analyze internet search patterns. Approval from Vanderbilt University's institutional review board and adherence to Strengthening the Reporting of Observational Studies in Epidemiology guidelines were confirmed. Monthly relative search volume (RSV) data for "migraine surgery," "Nurtec," and "Rimegepant" were collected from January 1, 2004, to November 11, 2023, within the United States. Statistical analysis involved determining mean monthly RSV values and percentage changes for critical periods. For "Nurtec," a significant surge in RSV occurred from March 2020 to April 2020 (344%). Additional peaks were observed from June 2020 to July 2020 (66%), October 2020 to December 2020 (169%), May 2021 to June 2021 (33%), and May 2023 to June 2023 (14%). "Migraine surgery" exhibited a notable 400% increase in RSV, from March 2005 to May 2005. However, post-2006, RSV for "migraine surgery" consistently remained low without noticeable peaks. The analysis of RSV trends for "Nurtec" and "migraine surgery" from 2004 to 2023 reveals the impact of pivotal events and marketing strategies on public interest. The distinct peaks in "Nurtec" RSV align with Food & Drug Administration approvals and marketing campaigns, highlighting the medication's accessibility. Conversely, the consistently low RSV for "migraine surgery" indicates limited awareness, emphasizing the need for enhanced promotion and education regarding surgical interventions.

ANALISIS SPASIAL PERUBAHAN TUTUPAN LAHAN PASCA KEBAKARAN HUTAN DAN LAHAN DI KABUPATEN MUARO JAMBI

Changes in land use and cover play an important role in sustainable natural resource management. Muaro Jambi Regency, which is rich in biodiversity, has ecosystem services for residents in the area, especially plantations which are one of the leading commodities. Forests as the largest land cover in Muaro Jambi Regency have experienced quite rapid changes, especially after forest and land fires occur almost every year. Real-time monitoring and assessment on a spatio-temporal basis is important to determine changes in land cover. This research examines changes in land cover in Sarolangun Regency from Landsat-8 time series images from 2018 to 2023. Land cover is classified into 6 classes using the supervised classification method. The data findings show that forests have experienced a significant decline, while settlements have experienced a very substantial increase. Comprehensive research regarding the vulnerability of periodic land cover changes at local and regional levels must be carried out to maintain sustainable environmental ecosystems.

Conceptual basis of architectural and urban planning heritage development in ethnic regions of Ukraine

The article describes the results of the philosophical and methodological analysis of the definitions - "formation", "concept" and "network" in the context of the preservation of architectural and urban heritage in ethnic regions of Ukraine. The relationship between these definitions and modern ideas about sustainable development and self-organization is revealed by their postmodern interpretation and architectural-sociological orientation. On this basis, two macrocosmic principles - the tectonicity of the formation of cultural focuses and the cyclicity nature of the sustainable development of ethnic regions, and two microcosmic principles - the architectonicity self-organization of the areas of these focuses’ and the ornamentality of their network is theoretically substantiated. These principles form the philosophical foundations of the formation of regional networks of historical centers of architectural and urban heritage on the territory of Ukraine. The principle of cyclicity reflects the recurrence of periodic changes in natural phenomena and stages of sustainable development of settlements and communities. The essence of the principle of tectonicity consists in the non-accidental placement of the overwhelming majority of focuses’ of architectural and urban heritage, which are provincial cities and towns, outside the zones of tectonic rupture dislocations and geopathogenic zones. The principle of architectonicity, which connects the natural and artificial environment, regulates the location of individual focuses’ and areas outside of fully urbanized territories, between highways and railways of national and international importance. The natural component of the architectonicity principle is rooted in the desire of a large part of historical provincial cities, towns, and villages to be located in a functionally and aesthetically attractive landscape environment - on the coasts of seas, lakes, and rivers, on the tops and slopes of hills, against the background of forest areas, etc. The principle of ornamentality integrates macrocosmic cyclicity and tectonicity with microcosmic architectonicity. It has a multi-layered structure, contains potentials, and becomes a regulator of the formation and sustainable development of the investigated network at all levels of its architectonical structure.

Nonlinear adaptive pose motion control of a servicer spacecraft in approximation with an accelerated tumbling target

Removing a limited number of large debris can significantly reduce space debris risks. These bodies are generally exposed to extreme environmental disturbance torques or consecutive accidents due to their large wet area, which causes them to experience accelerated high-rate tumbling motion. The existing literature has adequately explored the approximation operations with non-cooperative targets exhibiting 3-axis tumbling motion. However, the research gap lies in the lack of attention given to addressing this approximation for targets undergoing accelerated motion. Agile, accurate, and large-angle maneuvers are three common necessities for safely capturing such targets. Changes in the moment of inertia brought on by fuel slushing cannot be disregarded during such a maneuver. To deal with nonlinearities, adverse coupling effects, actuator saturation constraints, time-varying moment of inertia, and external disturbances that worsen during accelerated agile large-angle maneuvers, a novel adaptive control approach is developed in this paper. The controller's main advantage is its adjustable desired acceleration, which maintains its performance even when dealing with accelerated motion. The control law is directly synthesized from the nonlinear relative equations of motion, without any linearization or simplification of the system dynamics, making it robust to a variety of orbital elements and target behaviors. Adaptation laws are extracted from the Lyapunov stability theorem in a way that guarantees asymptotic stability. Moreover, control actuator roles (delay, saturation, and allocation) are accounted for in modeling and simulation. Finally, a comprehensive numerical simulation based on three different realistic and strict scenarios is carried out to demonstrate the effectiveness and performance of the proposed control approach. The controller's robustness against time-varying dynamic parameters (sharp and sudden change, smooth and slow change, and periodic change) is extensively demonstrated through simulation.

Iron biogeochemical redox cycling dominantly controls cadmium availability in acidic paddy soils

Periodic redox condition changes in acidic paddy soils substantially induce the biogeochemical redox cycling, and consequently affect Cd availability. However, the underlying biogeochemical mechanisms of the complicated redox processes in paddy soil remain poorly understood. Thus, we investigated the dynamics of Cd fractions under anoxic (0–40 days) and oxic (40–55 days) conditions. The available Cd content was evaluated using the diffusive gradients in thin film (DGT) technique, and the results show it decreased from 6.3 μg L–1 to below 0.1 μg L–1 under anoxic conditions, but rapidly increased to 13.5 μg L–1 under oxic conditions. Both sequential extraction procedures and X-ray absorption spectroscopy (XAS) analyses found that majority of available Cd transformed to organic matter complex and Fe-Mn oxides fractions, rather than bounded with sulfides. The soil chemical properties further evaluated, and the correlation analysis and principal component analysis results suggested that the key factors in soils for the available Cd was the SO42–, pH, and surface site concentration. The reduction of SO42– could generate sulfides which may precipitate with dissolved Cd. The biogeochemical redox cycling of Fe/N/S determined the changes of soil pH and consequently influenced adsorption behavior of Cd. The breakdown of the soil aggregations changed the surface site concentration, which may affect the immobilization of Cd. A process-based kinetic model was established, and it found that iron biogeochemical redox cycling dominated the changes of soil pH, and thereby contributed to majority Cd retention by Fe-Mn oxides (34.4 %) and organic matter (33.7 %). In addition, sulfur biogeochemical redox cycling only contributed to 13.6 % of the total Cd contents, because of relatively low Cd solubility in contaminated soils and the competition with other cations for limited sulfides. The findings provide robust targets for interpreting the iron and sulfur biogeochemical processes for Cd availability and would be helpful for developing the precise and effective remediation strategies in Cd-contaminated soils.

Impact of touristification and landscape pattern on habitat quality in the Longji Rice Terrace Ecosystem, southern China, based on geographically weighted regression models

Although the roles of tourism development and landscape value in the conservation of rice terraces have become increasingly important in recent years, rice terraces still face abandonment and desertification. Habitat quality (HQ) assessments evaluate the biodiversity conservation status of rice terraces; however, the spatial and temporal evolution of rice terrace HQ and influencing factors remains poorly understood. Here, a case study was performed of the Longji Terraces, Longsheng, Guangxi, China. Land use and land cover (LULC) remote sensing data for 1985–2020 (every 5 years) were obtained, and the InVEST-HQ model was used to evaluate and map the spatial and temporal evolution patterns and characteristics of HQ. A landscape pattern index and tourism indicators were combined and used to construct geographically weighted regression (GWR) models to explore the impact of tourism and landscape pattern on HQ. Our findings indicated that: (1) forests and terraces are the dominant landscape patches in Longji because they are better protected. Forest area and HQ changes exhibited temporal consistency, meaning that as forest area increased, HQ improved. (2) Longji Terraces exhibited optimum HQ overall, with a multi-year average of 0.977 and insignificant inter-annual variations. Spatially, the geographical HQ distribution was characterised by ‘low local levels, high global level.’ However, the percentage of HQ degraded areas in the final period reached 68 %, which is significantly greater than that of the improved areas (28 %). Moreover, improved areas had more spatial overlap with administrative villages that present superior tourism development. (3) HQ was significantly negatively correlated with night-time light (NTL), showed periodic changes (first negative, then positive) with Shannon’s diversity index (SHDI), was positively correlated with the contagion index (CONTAG), and showed periodic transitions (initially positive, then negative) with the mean of patch area (AREA_MN), population (POP), and patch density (PD). (4) Over time, the study area HQ showed weaker clustering and increased dispersion. In addition, the influence of tourism and landscape patterns increased from 2000 to 2020, with R2 increasing from 0.42 to 0.95. The results establish a scientific foundation for the conservation of rice terraces and sustainable use of landscape resources.

Detection of periodic peaks in Karenia brevis concentration consistent with the time-delay logistic equation

The logistic equation models single-species population growth with a sigmoid curve that begins as exponential and ends with an asymptotic approach to a final population determined by natural system carrying capacity. But the population of a natural system often does not stabilize as it approaches carrying capacity. Instead, it exhibits periodic change, sometimes with very large amplitudes. The time-delay modification of the logistic equation accounts for this behavior by connecting the present rate of population growth to conditions at an earlier time. The periodic change in population with time can progress from a monotonic approach to the carrying capacity; to oscillation around the carrying capacity; to limit-cycle periodic change; and, finally, to chaotic change.The presence of multiple species and inadequate sampling frequency and spatial coverage hinder the application of the time-delay logistic equation to real-world populations. Blooms of Karenia brevis along the southwest Florida Gulf Coast, however, provide a unique opportunity in that blooms are nearly monospecific and are sampled frequently over a wide geographic region; they are good candidates for testing the time-delay logistic equation. We show that these blooms exhibit peaks in concentration with periods in the range of 40–100 days, consistent with that predicted by the time-delay logistic equation. Cell concentrations in the valleys between the peaks are at least 2–3 orders of magnitude lower than peak values, offering predictable windows of opportunity for potential mitigation efforts.

A solution on parameter fluctuation of integrated on‐board battery chargers based on recursive least square algorithm

SummaryIntegrated on‐board battery chargers (IOBCs) are receiving increasing academic attention due to their low cost and low weight advantages. However, IOBCs suffer from periodic saturation, which causes periodic changes in inductance, which may lead to deterioration in control performance. Model‐free predictive control (MFPC) is a strongly robust control method that is suitable for solving the periodic saturation problem of IOBCs with pulsating magnetic fields. In this paper, a common single‐phase IOBC topology is used as an example, the causes of inductance fluctuations are analyzed, and finite element analysis (FEM) of motor inductance with different motor qualities is carried out. A recursive least squares (RLS)‐based solution method is proposed, and its convergence is analyzed. The feasibility of the proposed control scheme is experimentally verified.

Rolling discrete grey periodic power model with interaction effect under dual processing and its application

Time series characterized by periodic fluctuations are widespread in reality behavioural systems, and accurate forecasting of them has important practical application value. In this paper, based on the idea of discrete grey model, dual interaction effects and the nonlinear characteristics of the system are considered under the perspective of dual processing, and the fluctuating trend of the periodic sequence is portrayed through the introduction of the periodic dummy variable, and at the same time, combined with the extended periodic rolling time window method, the rolling discrete grey periodic power model with the interaction effect under dual processing is proposed, namely DIE-RDGM(1,1,T)α model. Differential evolution algorithm (DE) are employed to determine the optimum power index. Finally, the new model was compared with nine other forecasting models by three instances and applied to the problem of agricultural drought forecasting in Zhoukou City and Anyang City, Henan Province. The results show: (1) The new model has demonstrated strong competitiveness, confirming its rationality, validity, and superiority. (2) The DE is suitable for power index optimization search. (3) The new model can better describe the periodic change rule of seasonal-scale soil moisture in the two cities, and the forecast results are consistent with the actual drought conditions.

Simulation Analysis of Factors Affecting the Quantum Tunneling Effect in 1D Double Potential Barriers Structures

The working principle of a large number of modern scientific equipment has been applied to the quantum tunneling effect. Although the explanations for the relevant principles of this effect are clarified, the calculation process is very complex and difficult to understand. Previous studies combine specific applications without theoretical model references. This study adopts the method of using the time-independent Schrodinger equation to solve the wave function, which is more convenient to obtain the expression of transmission probability. Then, one discusses the relationship between transmission probability and potential barrier width, potential barrier spacing, and incident particle energy. The experimental results show that the transmission probability decreases exponentially from 1 to 0 as the potential barrier width gradually increases. As the potential barrier width increases, the transmission probability exhibits a clear periodic oscillation relationship, the oscillation period remains unchanged, and this paper derives the relationship between the oscillation period and the potential barrier width. As the incident energy of particles gradually increases, the transmission probability exhibits periodic changes, and the minimum value of transmission probability increases with the periodic changes. Based on the analysis, the smaller the potential barrier width, the greater the incident energy, and the more likely quantum tunneling occurs.

A record of change in oyster environment through high-resolution geochemical analysis of Late-Holocene sediments from Coastal Ghana

The near-coast environments where oysters occur are among the most impacted by humans globally, especially during the Late-Holocene. Yet, in West Africa, there is no documented historical record of change in these environments. We provide insight into the changing geochemical conditions of two oyster environments through high-resolution analysis of total organic carbon (C), total nitrogen (N), carbon and nitrogen isotope ratios (δ13C, δ15N), and trace elements, in two cores retrieved from the Densu estuary and the Anyanui (Keta) Creek in Ghana. Drastic shifts in sedimentation rate occurred in the Keta and Densu cores around 1996 CE and 960 CE respectively. At these times, comparatively, low levels of C and N were found in the Densu core. Increasing C and N levels and decreasing δ13C upcore aligned with the observed shift in sedimentation rate in the Keta core. The C/N ratios in the Keta core suggest allochthonous organic matter (OM) dominance in the creek. The Densu core showed periodic changes in C/N ratios from very high values (>20) between 1918 BCE and 1321 BCE, to values between 20 and 11 between 1321 BCE and 1977 CE and below 10 from the late 1970s CE to the present day, suggesting a varying degree of transformation in the catchment basin. Extremely high Sulfur (S) and moderate to significant Iron (Fe) increases suggest reducing conditions in the Keta sediments. Moderate Calcium (Ca), Zinc (Zn), and Strontium (Sr) concentrations in the upper part of the Densu core suggest a stronger influence of marine processes in the Densu in recent times. The findings reflect the impacts of catchment basin modification on the health of the two coastal environments, likely to impact the growth, productivity, and sustainability of the fishery of the West African mangrove Oyster.