Flux Components Research Articles

Effect of sorption-induced deformation on methane flow in kerogen slit pores

Shale gas production relies on the movement of methane through nanopores which are characterized by extra-low permeability in shale formations. However, there is a lack of understanding on methane transport in realistic organic nanopores, especially in relation to sorption-induced swelling. Here, using Monte Carlo and molecular dynamics simulations, the effect of kerogen deformation on gas transport is investigated by comparing the flow rate differences in slit pores with rigid (non-deformable) and flexible (deformable) kerogen matrices, constructed from 27 type II-D kerogen units. Simulation results show that sorption-induced swelling reduces methane mass flux significantly in large slit pores (20–40 Å) as pressure increases. By incorporating kerogen deformation into a diffusive-viscous gas flow model, it is concluded that the observed mass flux decrease is likely attributed to the narrowing pore size which mainly suppresses the viscous flux component. Further calculations suggest that kerogen swelling may decrease the apparent permeability of the slit pore by up to ∼40% within pore pressure of 50 MPa. Additional findings show that diffusion can enhance the maximum gas velocity in the slit pores threefold compared with the Hagen-Poiseuille equation when pore pressure is ∼2 MPa, and the diffusion and the viscous flow dominate the total mass flux when Kn > 10 and Kn < 0.1, respectively.

The effects of redistributed heat flux on ocean climate change in FAFMIP heat flux anomaly experiments

The Flux–Anomaly-Forced Model Inter-comparison Project (FAFMIP) aims to study the response of the ocean to changes in prescribed surface flux (heat, freshwater, and wind) caused by atmospheric CO2 increase. Among these surface flux perturbations, the heat flux has the greatest effect on ocean heat uptake (OHU), the Atlantic Meridional Circulation (AMOC), and sea level changes. This occurs in part because of the redistributed heat flux (Qr’), which is the component of the heat flux driven by ocean circulation changes and almost nearly doubles the initial heat flux perturbation (F) prescribed by FAFMIP in the North Atlantic (NA). In this study, we used a standalone ocean model to quantitatively investigate the impact of Qr’ on OHU and the AMOC in prescribed heat anomaly experiments (faf-heat experiment in FAFMIP). We also showed that whether the other two FAFMIP heat flux anomaly experiments (faf-heat-NA50pct and faf-heat-NA0pct) can reasonably simulate the ocean’s response to prescribed surface heat flux, especially OHU and AMOC. Our findings show that faf-heat-NA50pct is better because the redistribution-feedback (Qr’) nearly equals the initial perturbation (50%F) in the NA and thus recovers the total perturbation F in faf-heat. Although direct comparisons cannot be drawn, both faf-heat-NA50pct and faf-heat experiments with no effect of Qr’ cause AMOC weakening that is roughly comparable with the 1pctCO 2 experiments. The magnitude of simulated AMOC weakening in faf-heat-NA50pct is 3.9Sv, accounting for about 29% of the AMOC intensity in unperturbed experiment, which is closer to the faf-heat experiment (about 31%) with no effect of Qr’ relative to the faf-heat experiment. Because of negative Qr’ in all regions except the NA region especially for the Central and Eastern Equatorial Pacific and Southern Ocean, the simulated global OHU in faf-heat-NA50pct is reduced by 10% as compared to the added OHU in the faf-heat experiment. The Qr’ in the faf-heat experiment increases OHU by approximately 13% of the total OHU and further reduces AMOC intensity by 3.4 Sv, accounting for 26% of the AMOC strength in an unperturbed experiment. Faf-heat-NA0pct results in a significant reduction in OHU (approximately 26%), and the magnitude of AMOC weakening is only approximately 1.9 Sv, despite no F being added in the NA.

Automatic defect identification in magnetic particle testing using a digital model aided De-noising method

Magnetic particle testing (MPT) has high sensitivity, which is popular in ferromagnetic material detection. However, results of MPT always mix with fake magnetic particle indication (FMPI) and point noise caused by nonrelevant magnetic particles. It mainly depends on manual work to find defects in MPT. In this paper, Hough Transform, which is robust to the point noise, is introduced to automatically identify the linear features of magnetic particle indication (MPI) caused by defects. However, the algorithm cannot distinguish between the similarly shaped FMPI and MPI. To address the problem, we proposed a digital model aided de-noising Method. Specifically, the density of normal component of magnetic flux on specimen surface is calculated by finite element analysis to evaluate the possibilities of FMPI occurrence. Then detection results are compared with the calculation to eliminate FMPI. Experiments show that scratches on hub bearing can be successfully identified by the proposed method.

Land-use change emissions based on high-resolution activity data substantially lower than previously estimated

Land-use and land-cover changes (LULCCs) contributed around one third to the cumulative, anthropogenic CO2 emissions from 1850 to 2019. Despite its great importance, estimates of the net CO2 fluxes from LULCC (ELUC) have high uncertainties, compared to other components of the global carbon cycle. One major source of uncertainty roots in the underlying LULCC forcing data. In this study, we implemented a new high-resolution LULCC dataset (HILDA+) in a bookkeeping model (BLUE) and compared the results to estimates from simulations based on LUH2, which is the LULCC dataset most commonly used in global carbon cycle models. Compared to LUH2-based estimates, results based on HILDA+ show lower total ELUC (global mean difference 1960–2019: 541 TgC yr−1, 65%) and large spatial and temporal differences in component fluxes (e.g. CO2 fluxes from deforestation). In general, the congruence of component fluxes is higher in the mid-latitudes compared to tropical and subtropical regions, which is to some degree explained with the different implementations of shifting cultivation in the underlying LULCC datasets. However, little agreement is reached on the trend of the last decade between ELUC estimates based on the two LULCC reconstructions. Globally and in many regions, ELUC estimates based on HILDA+ have decreasing trends, whereas estimates based on LUH2 indicate an increase. Furthermore, we analyzed the effect of different resolutions on ELUC estimates. By comparing estimates from simulations at 0.01∘ and 0.25∘ resolution, we find that component fluxes of estimates based on the coarser resolution tend to be larger compared to estimates based on the finer resolution, both in terms of sources and sinks (global mean difference 1960–2019: 36 TgC yr−1, 96%). The reason for these differences are successive transitions: these are not adequately represented at coarser resolution, which has the effect that—despite capturing the same extent of transition areas—overall less area remains pristine at the coarser resolution compared to the finer resolution.

Water use in a young Pinus taeda bioenergy plantation: Effect of intensive management on stand evapotranspiration

AbstractThe increasing demand for plant‐derived bioenergy is projected to expand tree plantations with intensive silviculture and improved tree genetics. These silvicultural practices result in faster stand development and canopy closure, which may also influence the systems' water dynamics. Here, we studied the evapotranspiration (ET) of a young (5 years old) intensively managed loblolly pine (Pinus taeda) stand and investigated the components of ET to determine its contribution to overall water use. We also compared ET with plantations that received less intensive management to determine whether our stand used more water. We used the eddy covariance method to estimate ecosystem‐level total ET (ETEC), while plot‐level estimates of ET (ETP) were obtained via soil lysimeters, sap flow sensors, and throughfall collectors, enabling measurement of the components of ET. Soil evaporation (Es) was the largest component of ETP (36%) over the course of the study, while transpiration and canopy interception accounted for 27% and 22%, respectively. Es decreased with stand development, while transpiration and canopy interception increased. Leaf area index (LAI) and precipitation were the most significant factors controlling ET and its components. Compared to previous studies in different sites that have similar age but lower LAI, our stand had higher water use. This high water use in the early stages of stand development was primarily due to high Es before the canopy was fully developed. While there are potential sources of uncertainty when comparing ETEC and the component fluxes in ETP, results from the two methods were not significantly different. This study had the advantage of using multiple methods to understand and verify the component processes that contribute to ET. Therefore, we recommend that multiple measurement techniques be used in the long‐term observation of ET, and in particular for the evaluation of the impact that intensively managed forests have on water resources in the southeastern United States.

Spectral Properties and Hybrid Jet Model Constraints of Fermi GRB 210610B

The jet composition of gamma-ray bursts (GRBs) is still an open question and the energy spectrum characteristics can provide us with evidence. GRB 210610B is a special burst with low-energy indices that are all greater than the synchrotron cutoff. We first use two empirical models, Band and CPL, and one physics model, a blackbody, to perform time-resolved spectral analysis on GRB 210610B and find that about 76.47% of the spectra need an addition thermal component to obtain a better fit. Moreover, these spectra could be well fitted by a multicolor blackbody (mBB) and the synchrotron model. We then adopt the hybrid jet model proposed by Gao & Zhang to perform a “top-down” approach to diagnose the photospheric properties (η and σ 0) of the central engine from observational data. We find both the dimensionless entropy η and the magnetization parameters (1 + σ 0) are greater than 1, indicating that the Poynting flux component may play an important role in addition to the hot fireball component. Our analysis also shows that most of the spectra have a magnetization parameter (1 + σ 15) ≃ 1 at ∼1015 cm, suggesting that nonthermal emission may originate from internal shocks. Furthermore, we find that α and E p show different time evolution behaviors: α exhibits a “hard-to-soft” behavior and moderately correlates with flux, while E p exhibits a “tracking” behavior. The magnetic field strength B and the mBB parameter kT max also show a “tracking” behavior. Our results suggest that the empirical model CPL may be interpreted by an mBB.

Power Line Harmonic Radiation Observed by the Van Allen Probes Spacecraft

AbstractWe present a systematic analysis of Power Line Harmonic Radiation (PLHR) electromagnetic wave events observed by the Van Allen Probes spacecraft over the entire duration of the mission (2012–2019). PLHR events are radiated by electric power systems on the ground at harmonics of the base power system frequency (50 or 60 Hz, depending on the region). We analyze wave intensities at frequencies corresponding to the first few harmonics and we demonstrate that they are significantly enhanced at the times when the field‐aligned magnetic footprint of the spacecraft is above industrialized areas. Considering the spacecraft locations close to the equatorial plane, this represents experimental evidence that PLHR emissions may propagate up to radial distances as large as about 4 Earth radii. Average frequency spectra above selected industrialized regions reveal increased wave intensities at the frequencies corresponding to the first and the third harmonics, in particular during the nighttime. Multicomponent wave measurements allow us to perform a detailed wave analysis of polarization and propagation properties of the events. The waves are typically right‐handed elliptically or nearly circularly polarized, propagating with oblique wave normal angles from low latitude sources and more field‐aligned wave vectors from high latitude sources. The sign of the parallel component of the Poynting flux confirms that the events indeed propagate from the anticipated ground regions. Few events observed above the United States region propagate in the opposite direction, which is interpreted as wave bouncing between the hemispheres.

Drainage Ditch Cleaning Has No Impact on the Carbon and Greenhouse Gas Balances in a Recent Forest Clear-Cut in Boreal Sweden

Ditch cleaning (DC) is increasingly applied to facilitate forest regeneration following clear-cutting in Fennoscandinavia. However, its impact on the ecosystem carbon and greenhouse gas (GHG) balances is poorly understood. We conducted chamber measurements to assess the initial DC effects on carbon dioxide (CO2) and methane (CH4) fluxes in a recent forest clear-cut on wet mineral soil in boreal Sweden. Measurements were conducted in two adjacent areas over two pre-treatments (2018/19) and two years (2020/21) after conducting DC in one area. We further assessed the spatial variation of fluxes at three distances (4, 20, 40 m) from ditches. We found that DC lowered the water table level by 12 ± 2 cm (mean ± standard error) and topsoil moisture by 0.12 ± 0.01 m3 m−3. DC had a limited initial effect on the net CO2 exchange and its component fluxes. CH4 emissions were low during the dry pre-treatment years but increased particularly in the control area during the wet years of 2020/21. Distance to ditch had no consistent effects on CO2 and CH4 fluxes. Model extrapolations suggest that annual carbon emissions decreased over the four years from 6.7 ± 1.4 to 1.6 ± 1.6 t-C ha−1 year−1, without treatment differences. Annual CH4 emissions contributed &lt;2.5% to the carbon balance but constituted 39% of the GHG balance in the control area during 2021. Overall, our study suggests that DC modified the internal carbon cycling but without significant impact on the carbon and GHG balances.

Global methane and nitrous oxide emissions from inland waters and estuaries.

Inland waters (rivers, reservoirs, lakes, ponds, streams) and estuaries are significant emitters of methane (CH4 ) and nitrous oxide (N2 O) to the atmosphere, while global estimates of these emissions have been hampered due to the lack of a worldwide comprehensive data set of CH4 and N2 O flux components. Here, we synthesize 2997 in-situ flux or concentration measurements of CH4 and N2 O from 277 peer-reviewed publications to estimate global CH4 and N2 O emissions from inland waters and estuaries. Inland waters including rivers, reservoirs, lakes, and streams together release 95.18 Tg CH4 year-1 (ebullition plus diffusion) and 1.48 Tg N2 O year-1 (diffusion) to the atmosphere, yielding an overall CO2 -equivalent emission total of 3.06 Pg CO2 year-1 . The estimate of CH4 and N2 O emissions represents roughly 60% of CO2 emissions (5.13 Pg CO2 year-1 ) from these four inland aquatic systems, among which lakes act as the largest emitter for both CH4 and N2 O. Ebullition showed as a dominant flux component of CH4 , contributing up to 62%-84% of total CH4 fluxes across all inland waters. Chamber-derived CH4 emission rates are significantly greater than those determined by diffusion model-based methods for commonly capturing of both diffusive and ebullitive fluxes. Water dissolved oxygen (DO) showed as a dominant factor among all variables to influence both CH4 (diffusive and ebullitive) and N2 O fluxes from inland waters. Our study reveals a major oversight in regional and global CH4 budgets from inland waters, caused by neglecting the dominant role of ebullition pathways in those emissions. The estimated indirect N2 O EF5 values suggest that a downward refinement is required in current IPCC default EF5 values for inland waters and estuaries. Our findings further indicate that a comprehensive understanding of the magnitude and patterns of CH4 and N2 O emissions from inland waters and estuaries is essential in defining the way of how these aquatic systems will shape our climate.

Determination of β -decay feeding patterns of Rb88 and Kr88 using the Modular Total Absorption Spectrometer at ORNL HRIBF

Precise determination of ground-state feeding in the β decay of fission products is an important but challenging component in modeling reactor antineutrino flux and reactor decay heat. The Modular Total Absorption Spectrometer (MTAS) is a versatile NaI(Tl) detector array that determines the true β-decay pattern free from the pandemonium effect, including precise ground-state feeding intensities. In this paper, we report MTAS results of the β feeding intensities of Rb88 and Kr88, fission products with large cumulative yields in nuclear reactors. By comparing MTAS results with previous measurements, Rb88 provides a validation of MTAS's ability to determine ground-state feedings in β decays, while the precision of Kr88 ground-state feeding is improved when compared with the Evaluated Nuclear Structure Data File (ENSDF). The investigation of sources that contribute to β feeding branching uncertainties in MTAS experiments is discussed in detail. Lastly, the deconvolution of Rb88 decay spectra suggests that MTAS can distinguish an allowed β spectral shape from a first forbidden unique β spectral shape.1 MoreReceived 29 October 2021Accepted 15 April 2022DOI:https://doi.org/10.1103/PhysRevC.105.054312©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeta decayNuclear structure & decaysProperties59 ≤ A ≤ 89TechniquesNuclear data analysis & compilationSpectrometers & spectroscopic techniquesNuclear Physics

SIMULATION OF VAPN OPENING IN SLAG OF THE STEEL STEELING IN EAF OXIDATION PERIOD

An important problem in improving the slag mode of steelmaking in EAF is the substantiation of the rational component and chemical composition of fluxes that form the slag phase, the properties of which provide high performance and an energy-efficient mode of electric steelmaking. The kinetics of dissolution of lime in the slag of the oxidation period of steelmaking in EAF was studied by introducing a high-temperature furnace model (40 kg; LPZ-67 with periclase lining) onto the surface of the bath using limestone fractions of 3 and 10 mm with different degrees of firing.

On-Line Detection of Demagnetization for Permanent Magnet Synchronous Motor via Flux Observer

Demagnetization in permanent magnet synchronous motor (PMSM), caused by high temperature or inverse magnetic field, may increase loss and torque ripple, and even degrade the system stability in severe cases. On-line detection can identify the incipient demagnetization of permanent magnets (PMs), as well as providing reference for subsequent fault-tolerant control, so as to avoid further demagnetization. Therefore, an on-line demagnetization detection method is proposed in this paper by using flux observer. First, an observer is established in the three-phase stationary reference frame by taking the stator currents and the amplitudes of the fundamental and harmonic components of flux as state variables. Then, three demagnetization indexes are presented to evaluate the properties of PMs based on the observed flux information. The proposed method can directly track the amplitude of harmonic flux and evaluate the severity of the demagnetization more comprehensively. Simulation and experimental results demonstrate the effectiveness of the proposed method.

Lipid Expansion Microscopy

Membrane architectures whose dimensions and features are smaller than the diffraction limit of light orchestrate diverse cellular events such as lipid transport, vesicle formation, and calcium signaling. These structures, which include membrane invaginations, organelle contact sites, and membrane microdomains, are primarily composed of phospholipids, making methods to visualize these biomolecules vital to our understanding of cellular function. Techniques to accurately image phospholipid‐containing structures with fluorescence microscopy are challenged by the diffusion of lipids within the bilayer, even in fixed samples. Expansion microscopy (ExM) utilizes hydrogel formation to fix biomolecules in place and swell samples to produce high‐resolution images of protein‐ and nucleic acid‐containing cellular structures 30‐70 nm in size. Using chemical reporter metabolites and a novel multifunctional fluorophore probe, here we present Lipid Expansion Microscopy (LExM), which enables the high‐resolution imaging of phospholipids with a tunable expansion factor using the principles of ExM. We will present key synthetic and technological advances critical to the development of LExM as well as its application to visualize nanoscale membrane structures, phospholipid‐organelle colocalization, and the spatial component of flux through specific lipid biosynthetic pathways within intact cells.

Sensorless vector control scheme for an induction motor fed by MMC

ABSTRACT Due to its notable advantages, Modular Multilevel Converter (MMC) is considered to be employed for medium-voltage motor drives. In this paper, a high-performance sensorless vector control scheme inspired from the Model Reference Adaptive System (MRAS) approach is developed for an MMC-fed induction motor. Besides the well-known vector control scheme advantage, i.e. independent control of motor flux and torque, eliminating the speed sensor will notably improve the reliability of the proposed method. The motor flux components in the αβ frame are determined and used for estimating the speed value. As the errors of flux components calculated by the motor voltage and current models are continuously compensated by a MRAS-based loop, the estimation would be accurate for a wide range of speeds. Moreover, several modifications are considered to add the capability of voltage balancing for submodule capacitors, and also circulating current control to the proposed scheme. The two aforementioned features are necessary for efficient operation of MMC. Moreover, the circulating current control capability is mandatory for injection of different circulating current profiles, which is required for reducing the flying capacitors’ voltage ripples at low speeds. Finally, different performance aspects of the proposed method are experimentally assessed and validated.

Systematic improvement in simulated latent and sensible heat fluxes over tropical oceans in AMIP6 models compared to AMIP5 models with the same resolutions

Recent studies have shown that most Atmospheric Model Intercomparison Project (AMIP5) models that participated in the fifth phase of the coupled model intercomparison project (CMIP5) overestimate surface latent (QLH) and sensible (QSH) heat fluxes over tropical oceans. This study aims to quantify and understand any improvement in simulated QLH and QSH in AMIP6 models compared to AMIP5 models with the same horizontal resolutions. To accomplish this, we compare the Ocean Atmosphere air-sea Flux (OAFlux) dataset to nine AMIP5 and nine AMIP6 models integrated over 30 years (1979–2008). We found that all the AMIP5 and AMIP6 models overestimate both components of fluxes, but all of the AMIP6 models performed better than their AMIP5 counterparts over the tropical oceans (30°S-30°N). Yet, systematic spatial biases remain, which leads to only a small improvement in the simulated fluxes. For example, the root mean squared error (RMSE) and mean bias in QLH in AMIP5 are 30 and 21 W m−2 compared to 28 and 19 W m−2 in AMIP6. This is an improvement of 2 W m−2 for both RMSE and bias in QLH, yielding a reduction in QLH bias by 10% and RMSE by 7%. For QSH, an improvement of 1 W m−2 is seen in both bias and RMSE, yielding a reduction in QSH bias by 25% and RMSE by 13%. The primary reason for the improvement in QLH in AMIP6 is the better representation of the 10m wind speed and air-sea humidity difference than those in AMIP5. The improvement in QSH is due to an improvement in air-sea temperature difference. These results offer guidance to the modeling community to improve model simulation of near-surface meteorological variables in the tropics.

Model for non-equilibrium vacancy diffusion applied to study the Kirkendall effect in high-entropy alloys

The effect of the non-equilibrium vacancy on the Kirkendall porosity formation was studied by means of a developed model of the multi-component diffusion with vacancies (MDV) which includes the intrinsic fluxes with vacancy gradient and non-ideal sources and sinks for vacancies. For this study, the diffusion couple experiments in multi-component alloys were chosen. To handle the case of concentration-dependent equilibrium vacancy concentration, we introduced the interaction parameters between the components and vacancies, which can have strong effects on the equilibrium vacancy concentration in alloys and on thermodynamic factors. The diffusion profiles of components and vacancies were simulated by using thermodynamic and kinetic data. The different intensity of the vacancy annihilation/generation and different initial vacancy distributions were considered. Furthermore, we show that the conventional model of diffusion in multi-component systems is a particular case of the MDV with a specific sink/source term. The conventional model was extended by the vacancy diffusion term, similar to the MDV, which significantly reduces the vacancy gradient and the pore formation near the Matano plane. The numerical results demonstrate that the diffusion profiles of substitutional components slightly depend on the sink/source intensity if the none-zero net flux of substitutional components is not significant and the sources and sinks of vacancies are not sparse, whereas the porosity depends very strongly and correlates with the vacancy distribution. For the simulation of variable equilibrium vacancy concentrations using the MDV, the corresponding interaction parameters related to vacancies are necessary to be included in the thermodynamic assessment.

Plant functional traits play the second fiddle to plant functional types in explaining peatland CO2 and CH4 gas exchange

Peatlands constitute a significant soil carbon (C) store, yet the C gas flux components show distinct spatial variation both between and within peatlands. Determining the controls on this variability could aid in our understanding of the response of peatlands to global changes. In this study, we assess the usefulness of different vegetation related parameters to explain spatial variation in peatland C gas flux components. We hypothesise that spatial variation is best explained by trait-based indices (similarly to other terrestrial ecosystems), and that the impact of soil physicochemical properties, such as nitrogen (N) content or water level, can be manifested through the traits. Furthermore, we expect that the spatial variability associated with each of the C gas flux components can be explained by a distinct set of traits. To address our aim, we used a successional peatland chronosequence from wet meadows to a bog, along which all variables were recorded with similar methods and under similar climatic conditions.We observed spatial variability with all measured gas fluxes, with carbon dioxide (CO2) fluxes showing significant variability between sites, while within site variability was more important for methane (CH4) fluxes. As expected, our results show that the impacts of physicochemical conditions were directed via vegetation. However, the cover of functional plant types that capture multiple traits proved to be more powerful in explaining gas flux variability compared to functional trait-based indices. Our findings imply that for future gas flux modelling purposes, rather than attempting to use individual traits - as is the ongoing trend in ecology - it might be more useful to refine plant functional groupings and ensure they are based on a set of plant traits relevant for the studied ecosystem process. This could be facilitated by the collation of a large data set of traits measured from peatlands.

Relationship between the Intraseasonal Oscillation over Mid-High-Latitude Eurasia and the Stratospheric Sudden Warming Event in February 2018

Taking the stratospheric sudden warming (SSW) event in February 2018 as an example, the relationship between the SSW event and the intraseasonal oscillation (ISO) mode over mid-high-latitude Eurasia is investigated by daily reanalysis data. First, the 2018 SSW event and mid-high-latitude ISO are reviewed. The 2018 SSW event is a typical vortex-split event defined by the NCEP-DOE dataset, and the ISO mode features a southeastward propagation. Along with the ISO propagation, temperature anomalies developed from troposphere to stratosphere in the 2018 wintertime. It is also found that a strong ISO event occurred before the onset of SSW in this wintertime. Our analysis reveals that the correlation is significant when mid-high-latitude ISO leads the 2018 SSW event by 9–13 days. Occurrence of strong ISO 9–13 days before the SSW event is found to be conducive to its onset. The diagnosis of planetary wave activity indicates that stronger ISO leads to strengthened wavenumber-2 geopotential height anomalies; then, its in-phase superposition of climatological geopotential height makes up for the upward-propagating tropospheric planetary waves, which is in favor of the onset of the 2018 SSW event. The outcome of energy conversion equations also reveals that ISO perturbation contributes to the onset of SSW. Lastly, the contribution of the vertical component of Plumb wave activity flux propagated upward from the region of mid-high-latitude ISO is estimated at approximately 69%.

Recent progress, liquid metal use as plasma facing component and vapor shielding of high heat flux

Recent progress, liquid metal use as plasma facing component and vapor shielding of high heat flux

Assessment of submarine groundwater discharge (SGD) and associated nutrient subsidies to Xiangshan Bay (China), an aquaculture area

Submarine groundwater discharge (SGD) is a predominant component of chemical fluxes in the solute budgets in coastal ecosystems because of its large flux and the corresponding concentrated constituents. A quantitative study regarding the mass balance model of 226Ra and 228Ra was performed to assess SGD and associated nutrient inputs in Xiangshan Bay (XSB), a typical Chinese aquaculture bay. Based on these mass balance models, the SGD rates in the XSB Channel were 8.9–13.2 cm d−1. The SGD rates in the three corresponding embayments were 3.5–3.7 cm d−1 in Embayment I, 5.6–5.8 cm d−1 in Embayment II, and 4.5–5.8 cm d−1 in Embayment III. Significant spatial variabilities in SGD rates were observed in the different XSB districts, reflecting that ocean dynamics and anthropogenic activities play significant roles at different scales. SGD-derived nutrient fluxes in XSB were the dominant sources of nutrient loading, and their magnitudes were approximately 1–2 orders larger than those of riverine input. SGD rates in the XSB Channel were approximately three times higher than those in the three embayments, but the SGD-derived nutrient rates in the XSB Channel were comparable with those in the three embayments, even significantly lower than that for NO3-N in the inner regions of the embayment. These results imply that aquaculture activities and urbanization jointly influence SGD. When combined with the results of other studies, our observations demonstrate the significant comprehensive effects of multiple factors on SGD, a critical but overlooked nutrient source.