Dynamic Transport Processes Research Articles

Structural Insight on the Selectivity of Calyx[4]Arene-Based Inhibitors of Mg2+-Dependent Atp-Hydrolases.

Located in plasma membranes, ATP hydrolases are involved in several dynamic transport processes, helping to control the movement of ions across cell membranes. ATP hydrolase acts as a transport protein, converting energy from ATP hydrolysis into transport molecules against their concentration gradients. In addition to energy metabolism and active transport, ATP hydrolase is essential for maintaining cellular homeostasis and cell function. This study focused on the domain architecture model of P-type ATPases, which participate in the reaction cycles of ATP hydrolysis carried out by membrane transport systems - Na+, K+-ATPase and Ca2+, Mg2+-ATPase. Targeted modulation of Na+, K+-ATPase and Ca2+, Mg2+-ATPase by unnatural drugs is of greatest interest due to the lack of known effectors. This new discovery presents a convenient model based on our recent experimental studies of the membrane structures and myocytes of the uterine smooth muscle, the myometrium. This current study strongly supports the fact that nanosized calix[4]arenes functionalised on the upper rings of the macrocycle with biologically active phosphonic acid fragments can serve as selective and potent inhibitors of cation-transporting electroenzymes. This is how we discovered that calix[4]arene of methylenebisphosphonic acid C-97 and calix[4]arene of bis-aminophosphonic acid C-107 selectively and effectively (I0.5 <100 nM) inhibit the activity of Mg2+, ATP-dependent electrogenic Na+ K+ plasma membrane pump. As drug discovery in the field of Mg2+-ATPase inhibitors is uncharted territory, basic research holds the key to explaining and predicting the mechanism of interaction and action of different classes of compounds. In light of the presented results, new calix[4]arene compounds can be used as potent inhibitors of Mg2+, ATP-dependent electrogenic ion pumps.

A thermal infrared imaging observation system for the measurement of overland flow velocities under controlled laboratory conditions

Flow velocity is an important physical parameter in characterizing the hydraulics of water flow. The accurate measurement of overland flow velocities has great significance for understanding and modeling sediment transport and soil erosion. In this study, a Thermal Infrared Imaging Observation System (TIIOS) based on thermal infrared imaging techniques and computer vision recognition technology was established to measure overland flow velocities under controlled laboratory conditions. TIIOS has three subsystems including thermal tracer control, image acquisition and transmission, and image storage and processing. It can be used to dynamically monitor changes in shallow flow velocity by means of automatic control of thermal tracer, instantaneous image acquisition, image correction, noise removal and centroid determination. The observation precision was high with a standard deviation of 0.004 m·s−1 for flow velocity, a temporal resolution of 1/9th s, and a spatial resolution of 2 mm. The new system achieved higher accuracy compared to the traditional dye tracing and salt tracing techniques in observing the dynamic transport process of thermal tracer movement. The relative errors of the centroid velocity measured by the TIIOS ranged from −9.83 % to 6.40 %; whereas the relative errors of centroid velocity measured by salt tracer ranged from −21.36 % to 17.22 %. Measurements by the established TIIOS under different hydraulic conditions demonstrate that the relative errors of the centroid velocity are all smaller than those of the leading-edge velocity. This observational system provided a reliable way to measure shallow flow velocity for better understanding the mechanisms of water erosion processes and showed its potential to be used in field experiments under natural conditions.

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.

Simulation of the dynamic processes of microplastic suspension and deposition in a lake sediment-water system.

The occurrence of microplastics in aquatic environments has attracted increasing interest from both the public and scientists, especially their migration behaviors. Although several environmental behaviors of microplastics have been studied, the issue of microplastic suspension and deposition in lake sediment-water systems remains to be elucidated. In this study, we built an indoor sediment-water system with input and output rivers that simulated the actual situations in lakes, and aimed to explore the suspension and deposition behavior of microplastics using eight group experiments. The abundance of microplastics in overlying water and sediments in different periods was analyzed, and the characteristics of hydrodynamic disturbance on microplastic suspension and deposition were identified. Importantly, the exchange of microplastics in sediments and water under dynamic flow conditions was assessed. The results showed that the middle-scale experiment designed in this study effectively simulated the dynamic transport process of microplastics in lakes, and the hydrodynamic force had a significant impact on the suspension and deposition behaviors of microplastics. The average abundance of polystyrene, polyethylene terephthalate and polyamide microplastics was 1.07, 0.60 and 0.83 particles/L in overlying water during the suspension experiments, respectively. This showed a pattern of first rising and then falling with the extension of suspension time. Even in the environment with the maximum input water volume (8000 ml/min) in this study, only microplastics at a depth of 0 to 2 cm from the sediment were suspended. The average abundance of microplastics was 313.02 particles/kg during the deposition experiments, which gradually increased with the extension of deposition time in sediments. Finally, microplastic sizes in water of the suspension experiments and in sediments of the deposition experiments were concentrated in the range of 500 to 1500 μm and 300 to 1000 μm, respectively.

In vivo quantitative characterization of nano adjuvant transport in the tracheal layer by photoacoustic imaging.

Adjuvants are indispensable ingredients in vaccine formulations. Evaluating the in vivo transport processes of adjuvants, particularly for inhalation formulations, presents substantial challenges. In this study, a nanosized adjuvant aluminum hydroxide (AlOOH) was synthesized and labeled with indocyanine green (ICG) and bovine serum albumin (BSA) to achieve strong optical absorption ability and high biocompatibility. The adjuvant nanomaterials (BSA@ICG@AlOOH, BIA) were delivered as an aerosol into the airways of mice, its distribution was monitored using photoacoustic imaging (PAI) in vivo. PAI results illustrated the gradual cross-layer transmission process of BIA in the tracheal layer, traversing approximately 250 µm from the inner layer of the trachea to the outer layer. The results were consistent with pathology. While the intensity of the BIA reduced by approximately 46.8% throughout the transport process. The ability of PAI for quantitatively characterized the dynamic transport process of adjuvant within the tracheal layer may be widely used in new vaccine development.

Dynamic and Asymmetrical Ion Concentration Polarization in Dual Nanopipettes.

Dual nanopipettes with two channels have been receiving great attention due to the convenient experimental setup and multiple measuring channels in sensing applications at nanoscale, while the involved dynamic and asymmetrical ion transport processes have not been fully elucidated. In this paper, both experimental and simulation methods are used to investigate the dynamic mass transport processes inside dual nanopipettes with two well-separated channels. The results present that the ion transport resistance through the two channels (R12) is always the add-up of the individual ones (R13 + R23) with respect to the bulk solutions, at various ionic strengths and scan rates. A constant zero-current potential is obtained when loading an asymmetrical electrolyte concentration in the two channels, and the zero-potential current displays a good linear relationship with the bulk concentration outside the pipet. Besides revealing the dynamic and asymmetrical concentration polarization in the dual nanopipettes, these results would also further promote the better usage of dual nanopipettes in electrochemical sensing and imaging applications.

Solute trapping and non-equilibrium microstructure during rapid solidification of additive manufacturing

Solute transport during rapid and repeated thermal cycle in additive manufacturing (AM) leading to non-equilibrium, non-uniform microstructure remains to be studied. Here, a fully-coupled fluid dynamics and microstructure modelling is developed to rationalise the dynamic solute transport process and elemental segregation in AM, and to gain better understanding of non-equilibrium nature of intercellular solute segregation and cellular structures at sub-grain scale during the melting-solidification of the laser powder bed fusion process. It reveals the solute transport induced by melt convection dilutes the partitioned solute at the solidification front and promotes solute trapping, and elucidates the mechanisms of the subsequent microstructural morphology transitions to ultra-fine cells and then to coarse cells. These suggest solute trapping effect could be made used for reducing crack susceptibility by accelerating the solidification process. The rapid solidification characteristics exhibit promising potential of additive manufacturing for hard-to-print superalloys and aid in alloy design for better printability.

In Situ Measurements of Dynamic Bacteria Transport and Attachment in Heterogeneous Sand-Packed Columns.

Prevention, mitigation, and regulation of bacterial contaminants in groundwater require a fundamental understanding of the mechanisms of transport and attachment in complex geological materials. Discrepancies in bacterial transport behaviors observed between field studies and laboratory experiments indicate an incomplete understanding of dynamic bacterial transport and immobilization processes in realistic heterogeneous geologic systems. Here, we develop a new experimental approach for in situ quantification of dynamic bacterial transport and attachment distribution in geologic media that relies on radiolabelingEscherichia coliwith positron-emitting radioisotopes and quantifying transport with three-dimensional (3D) positron emission tomography (PET) imaging. Our results indicate that the highest bacterial attachment occurred at the interfaces between sand layers oriented orthogonal to the direction of flow. The predicted bacterial attachment from a 3D numerical model matched the experimental PET results, highlighting that the experimentally observed bacterial transport behavior can be accurately captured with a distribution of a first-order irreversible attachment model. This is the first demonstration of the direct measurement of attachment coefficient distributions from bacterial transport experiments in geologic media and provides a transformational approach to better understand bacterial transport mechanisms, improve model parametrization, and accurately predict how local geologic conditions can influence bacterial fate and transport in groundwater.

Dam removal effect on the lower St. Regis River ice-jam floods

The Hogansburg Dam in Akwesasne, NY, on the lower St. Regis River, a tributary of the St. Lawrence River, was decommissioned and removed in 2016. The dam removal restored over 893 river km of migratory fish access. However, ice jams occurred on the lower St. Regis River in winter before and after the dam removal, which caused flooding in the St. Regis Mohawk Tribe Reservation. This study reviewed the historical ice-jam conditions in the lower St. Regis River and the effect of dam removal. A two-dimensional river-ice model, DynaRICE, capable of simulating the dynamic ice transport and jamming processes, was used to evaluate pre- and post-dam-removal conditions of the Hogansburg Dam on the ice-jam flooding in the St. Regis Mohawk Tribe Reservation. The study showed that the dam removal effect decreases as the breakup discharge increases. A potential mitigation scheme for reducing ice-jam floods in the Hogansburg area using ice booms was examined and recommended.

Characterizing water vapor adsorption on coal by nuclear magnetic resonance: Influence of coal pore structure and surface properties

Steam injection is a novel and promising technology for enhancing coalbed methane (CBM) recovery. Accurate descriptions of the migration and adsorption of water vapor on coal is crucial for determining the occurrence state of the CBM and improving CBM production. This study quantitatively characterized the dynamic transport and adsorption processes of water vapor in coal pores and fractures using nuclear magnetic resonance (NMR). The results demonstrated that water vapor was preferentially adsorbed in the coal micropores, which was mainly related to capillary condensation, whereas liquid water filled a wide range of pores and fractures. Due to the differences in the microstructure and surface properties among different coals, the water vapor adsorption behaviors varied significantly. Among the coals used in this study, water vapor was most easily adsorbed on the bitumite with the biggest specific surface area, pore volume, pore area, the highest content of oxygen-containing functional groups, and the strongest wettability. Additionally, the coal pore structure had a greater impact on the water vapor adsorption capacity than the oxygen functional groups and the wettability. This research is of great significance for understanding the flow behaviors of water vapor in porous media and the interactions between coal and water.

Quantitative characterization of water transport and wetting patterns in coal using LF-NMR and FTIR techniques

Water injection in coal seams is an effective technique for preventing and controlling dust disasters in coal mines. However, there is a lack of quantitative evaluation of water transport in coal and its wetting effect. In this paper, the wetting experiments of coal samples with different coal rank and particle size at a given water volume were characterized using low-field nuclear magnetic resonance (LF-NMR) tests. Additionally, the physicochemical properties of coal were investigated by Fourier transform infrared (FTIR) and low temperature N2 adsorption (LTNA) experiments, establishing quantitative relationships between these properties and contact angle, T2-weighted average value (T2g), and peak area of adsorbed water (ATotal). The relationships reveal the dynamic transport process of water in coal samples and its wettability law. The results show that the relaxation time of free state water in porous media decreases with stronger wetting of coal samples, resulting in a faster relaxation rate of free state water and a leftward shift of corresponding peaks. In the range of coal particle sizes from 0.18 to 2 mm (10–80 mesh), the wettability of coal deteriorates with the increasing degree of deterioration of coal samples, with larger particles of lower rank coal samples exhibiting better wettability. The better the wettability of the coal, the shorter the relaxation time of the corresponding peaks, the larger the total area of the adsorption peaks, and the smaller the T2g,24h values. The FTIR structural parameters of hydroxyl (–OH) and carboxyl (–COOH) groups have the greatest influence on the hydrophilicity of the coal. Correlations of factors affecting the wettability of the coal body were analyzed, and three equations for quantitative characterization of the wettability of the coal body were constructed. Overall, the low-field NMR method presented in this paper provides an efficient means of quantitatively characterizing coal wettability and revealing the macro and microscopic mechanisms underlying the interaction between coal and water, as well as the associated wettability patterns.

Simulation of Transient Topside Layer in the Martian Ionosphere

Many Mars missions, e.g., Mariner, Viking, Mars Global Surveyor (MGS), Mars Express (MEX), and Mars Atmosphere and Volatile Evolution (MAVEN), have been launched to study the Martian atmosphere. These observations have improved our understanding of the ionosphere of Mars. Observations show that the Martian ionosphere could be divided into an M2 layer (at ~140 km altitude) and an M1 layer (at ~110 km altitude), ionized by EUV and X-ray solar radiation, respectively. However, there are still many scientific questions about the Martian ionosphere. A transient topsider layer (also called the M3 layer, at ~160–~220 km) can frequently be measured above the M2 layer in the Martian ionosphere. The statistical characteristics of the M3 layer show that it is not irradiated by solar incident radiation. Many candidate mechanisms have been suggested to explain the formation of the M3 layer. However, the method of describing or modeling the M3 layer is still one of the many open scientific questions about the Martian ionosphere. This study used a one-dimensional model, including photochemical production, loss, and dynamic transport processes to simulate the transient topside layer in the Martian ionosphere. The M3 layer was reproduced by a perturbed vertical plasma drift in this study. The enhancement of the electron temperature induced by the dynamic process of plasma could facilitate the formation of the M3 layer. Our results show that the vertical transport process of plasma might be more crucial in producing the M3 layer in the topside Martian ionosphere.

Transducer-Less Thermoreflectance Technique for Measuring Thermal Properties of the Buried Buffer Layer and Interface in GaN-based HEMTs

Measuring the thermal properties of the buried GaN buffer layer and interface in GaN high-electron mobility transistor (HEMT) structures is of crucial importance. This remains challenging with the traditional pump–probe thermoreflectance techniques due to their limited thermal penetration depths and the difficulty in extracting the large number of unknown parameters in the multilayer HEMT structure. This work applies a transducer-less transient thermoreflectance technique (TL-TTR) for the characterization. We experimentally and numerically investigate the dynamic thermal transport process of the TL-TTR measurement, benchmarking against that of the traditional metal transducer transient thermoreflectance (MT-TTR) measurement. The significantly different heat absorption and dissipation processes in the two measurements lead to the distinctive measurement sensitivities. Notably, the sensitivity of TL-TTR signal to all unknown thermal properties follows a distinctive trend over the measurement time region, demonstrating the technique’s capability of measuring the buried buffer thermal conductivity and the thermal boundary conductance (TBC) across the buffer/substrate interface. This is illustrated by measuring three different GaN-on-SiC wafers with highly Fe-doped buffer layers. The uncertainties of buffer thermal conductivity and TBC, determined by TL-TTR, are as low as ±6 and ±13%, respectively. In contrast, MT-TTR measures the buffer thermal conductivity and TBC with the uncertainties as large as ±20 and ±30%. The TL-TTR technique enables a non-invasive platform to characterize the thermal properties of the advanced GaN-based materials with complex structures and achieve a more in-depth understanding the phonon transport mechanisms.

Rapid reappearance of air pollution after cold air outbreaks in northern and eastern China

Abstract. The cold air outbreak (CAO) is the most important way to reduce air pollution during the winter over northern and eastern China. However, a rapid reappearance of air pollution is usually observed during its decay phase. Is there any relationship between the reappearance of air pollution and the properties of CAO? To address this issue, we investigated the possible connection between air pollution reappearance and CAO by quantifying the properties of the residual cold air mass after CAO. Based on the analyses of recent winters (2014–2022), we found that the rapid reappearance of air pollution in the CAO decay phase has an occurrence frequency of 63 %, and the air quality in more than 50 % of CAOs worsens compared to that before CAO. The reappearance of air pollution tends to occur in the residual cold air mass with a weak horizontal flux during the first 2 d after CAO. By categorizing the CAOs into groups of rapid and slow air pollution reappearance, we found that the residual cold air mass with a moderate depth of 150–180 hPa, a large negative heat content, and small slopes of isentropes is favorable for the rapid reappearance of air pollution. Among these factors, the cold air mass depth is highly consistent with the mixing layer height, below which most air pollutants are found; the negative heat content and slope of isentropes in the cold air mass jointly determine the intensity of low-level vertical stability. The rapid reappearance of air pollution is also attributed to the maintenance of the residual cold air mass and the above conditions, which are mainly regulated by the dynamic transport process rather than diabatic cooling or heating. Furthermore, analysis of the large-scale circulation of CAOs in their initial stage shows that the anticyclonic (cyclonic) pattern in northern Siberia (northeastern Asia) can be recognized as a precursor for the rapid (slow) reappearance of air pollution after the CAO.

Numerical modeling of ion transport and adsorption in porous media: A pore-scale study for capacitive deionization desalination

A pore-scale model is presented to simulate the dynamic ion transport and adsorption processes in porous electrodes used for capacitive deionization (CDI). The Stokes equation governing water flow is solved using the lattice Boltzmann method and Nernst-Planck equation describing ion transport is solved using the finite volume method. The ion adsorption process is considered at the surface of carbon electrodes. After validation against analytical solutions and published results, the model is used to study the coupled water flow, ion transport and adsorption in both two-dimensional and three-dimensional porous CDI electrodes at the pore scale. The effect of electrode microstructure, electrical potential and flow velocity on the adsorption processes is quantitatively investigated, and the relative importance of various parameters is determined. The presented model can be a powerful numerical tool to quantitatively analyze ion transport and adsorption in porous electrodes, and may provide useful information for the design and optimization of CDI electrodes and operating conditions for desired desalination efficiency, water throughput and cost.

Index Modulation Embedded in Type I Waveguide Written by Femtosecond Laser in Fused Silica.

Slit-shaped laser beams focused in bulk optical materials can realize embedded waveguides with circular cross sections consisting of positive index change type I traces. In these kinds of waveguide traces, a peculiar periodical refractive index modulation was observed in type I waveguides with two different femtosecond lasers. The direction of refractive index modulation can be controlled with the slit configuration, and its period can be controlled by mechanical perturbation of the stages and the scanning speed. We argue that platform perturbation and dynamical thermal transport processes during the scan are generating factors in the appearance of this modulation. The embedded microstructures in waveguides can provide spectrum modulation, which may have potential applications in optical sensing, filtering, and phase control.

Modeling of multiphase mass and heat transfer in fractured high-enthalpy geothermal systems with advanced discrete fracture methodology

Multiphase mass and heat transfer are ubiquitous in the subsurface within manifold applications. The presence of fractures over several scales and complex geometry magnifies the uncertainty of the heat transfer phenomena, which will significantly impact, or even dominate, the dynamic transport process. Capturing the details of fluid and heat transport within the fractured system is beneficial to the subsurface operations. However, accurate modeling methodologies for thermal high-enthalpy multiphase flow within fractured reservoirs are quite limited. In this work, multiphase flow in fractured geothermal reservoirs is numerically investigated. A discrete-fracture model is utilized to describe the fractured system. To characterize the thermal transport process accurately and efficiently, the resolution of discretization is necessarily optimized. A synthetic fracture model is firstly selected to run on different levels of discretization with different initial thermodynamic conditions. A comprehensive analysis is conducted to compare the convergence and computational efficiency of simulations. The numerical scheme is implemented within the Delft Advanced Research Terra Simulator (DARTS), which can provide fast and robust simulation to energy applications in the subsurface. Based on the converged numerical solutions, a thermal Péclet number is defined to characterize the interplay between thermal convection and conduction, which are the two governing mechanisms in geothermal development. Different heat transfer stages are recognized on the Péclet curve in conjunction with production regimes of the synthetic fractured reservoir. A fracture network, sketched and scaled up from a digital map of a realistic outcrop, is then utilized to perform a sensitivity analysis of the key parameters influencing the heat and mass transfer. Thermal propagation and Péclet number are found to be sensitive to flow rate and thermal parameters (e.g., rock heat conductivity and heat capacity). This paper presents a numerical simulation framework for fractured geothermal reservoirs, which provides the necessary procedures for practical investigations regarding geothermal developments with uncertainties.

East Asian monsoon and sea-level controls on clay mineral variations in the southern South China Sea since the Last Glacial Maximum

Clay minerals preserved in marine sediments carry important information about sediment transport processes from sources to sinks. To reveal the dynamic transport processes of clay minerals and related controlling factors in the southern South China Sea, spatiotemporal variations of clay mineral assemblages from previous studies (Cores MD05-2893, CG2, SO18287-3, MD01-2393, SO18383-3, and MD97-2150) are integrated to assess their controlling factors over the past 30 ka. Based on the smectite/(illite + chlorite) ratio in six cores, we found that the clay mineral variations on the continental slope off Sunda Shelf (Cores MD05-2893, CG2, and SO18287-3) have been controlled by the sea-level changes during the last glacial sea-level lowstand and by the East Asian monsoon during the Holocene sea-level highstand periods. Meanwhile, the clay mineral variations on the continental slope off the Mekong River (Cores MD01-2393, SO18383-3, and MD97-2150) have been driven by the chemical weathering in the Mekong River basin that associates with the East Asian summer monsoon evolution. Accordingly, we conclude that the glacial-interglacial variation of clay minerals in an integrated picture of the southern South China Sea region since the Last Glacial Maximum has been mainly controlled by sea-level change and East Asian monsoon evolution. However, these controlling factors play independent roles in different parts of the southern South China Sea, which appears more heterogeneous than generally expected.

Pore-scale investigation on ion transport and transfer resistance in charged porous media with micro-macro structure

Capacitive deionization is an electrochemical desalination technology, in which ions are removed from aqueous solution using porous carbon electrodes. Poisson-Nernst-Planck equations are fully solved by the lattice Boltzmann method to investigate the dynamic ion transport and adsorption processes from macropores between carbon particles into micropores inside carbon particles. Effects of potential, ion concentration and thickness of the microporous zone on the dynamic ion transport processes are investigated. Pore-scale results show that the ion transport first occurs at the micropore/macropore interface and then extends to the inner part of the microporous zone. Adsorption of Na+ ion consumes more time to reach the equilibrium state compared with expulsion of Cl− ion, and the ion concentrations of microporous zones in the steady state predicted by simulations agree well with the results obtained by the Donnan model. The kinetic rate parameters of the finite-rate ion transport model are obtained using data fitting based on the individual ion transfer fluxes into micropores calculated by the pore-scale simulation. It is found that identified kinetic rate parameters are constant showing the validity of the model, and the thickness of the microporous zone has a great influence on the values.

Evaluating the dynamics of groundwater, lakebed transport, nutrient inflow and algal blooms in Upper Klamath Lake, Oregon, USA

Transport of nutrients to lakes can occur via surface-water inflow, atmospheric deposition, groundwater (GW) inflow and benthic processes. Identifying and quantifying within-lake nutrient sources and recycling processes is challenging. Prior studies in hypereutrophic Upper Klamath Lake, Oregon, USA, indicated that ~60% of the early summer phosphorus (P) load to the lake was internal and hypothesized to be lakebed sediment release. Dynamic nutrient transport processes were examined to better characterize the nutrient sources. One-dimensional heat transport models calibrated to observed lakebed temperatures and a cross-sectional GW flow model provided estimates of GW-inflow rates that were greatest in spring and decreased through summer. One-dimensional solute transport models calibrated to observed lakebed pore-water dissolved silica (Si) and dissolved phosphate-phosphorus (DP) concentrations indicated that nutrients were transported from the lakebed by advection, diffusion, and enhanced mixing by benthic organisms and waves, and that DP removal occurred near the lakebed interface. Estimated water, Si, DP and total-phosphorus (TP) budgets indicated that GW contributed 21% of lake water inflow and at least 26, 20 and 16% of total Si, DP and TP inflow, respectively, when conservatively assuming background GW nutrient concentrations. However, lakebed GW (LGW) is enriched in nutrients during flow through lakebed sediment and the estimated GW contribution increased to 29 (33), 49 (67) and 43% (61%) of total Si, DP and TP inflow, respectively, if 20% (50%) of GW inflow to the lake was assumed to have LGW concentrations. Net nutrient inflow to the lake was greatest in spring and coincident with the annual diatom bloom. Inflowing dissolved nutrients appear to be assimilated by diatoms during the spring and become available for the summer Aphanizomenon flos-aquae bloom when the diatoms senesce. Thus, nutrient-enriched GW inflow and nutrient recycling by successive algal blooms must be considered when evaluating internal nutrient loading to lakes.