Changes In Flow Velocity Research Articles

Cerebral lateralisation of first and second languages in bilinguals assessed using functional transcranial Doppler ultrasound

Background: Lateralised language processing is a well-established finding in monolinguals. In bilinguals, studies using fMRI have typically found substantial regional overlap between the two languages, though results may be influenced by factors such as proficiency, age of acquisition and exposure to the second language. Few studies have focused specifically on individual differences in brain lateralisation, and those that have suggested reduced lateralisation may characterise representation of the second language (L2) in some bilingual individuals.Methods: In Study 1, we used functional transcranial Doppler sonography (FTCD) to measure cerebral lateralisation in both languages in high proficiency bilinguals who varied in age of acquisition (AoA) of L2. They had German (N = 14) or French (N = 10) as their first language (L1) and English as their second language. FTCD was used to measure task-dependent blood flow velocity changes in the left and right middle cerebral arteries during phonological word generation cued by single letters. Language history measures and handedness were assessed through self-report. Study 2 followed a similar format with 25 Japanese (L1) /English (L2) bilinguals, with proficiency in their second language ranging from basic to advanced, using phonological and semantic word generation tasks with overt speech production.Results: In Study 1, participants were significantly left lateralised for both L1 and L2, with a high correlation (r = .70) in the size of laterality indices for L1 and L2. In Study 2, again there was good agreement between LIs for the two languages (r = .77 for both word generation tasks). There was no evidence in either study of an effect of age of acquisition, though the sample sizes were too small to detect any but large effects. Conclusion: In proficient bilinguals, there is strong concordance for cerebral lateralisation of first and second language as assessed by a verbal fluency task.

Experimental Study on the Effect of Triangular Plate Barrier Height on Flow Velocity Distribution in Open Channels

Open and closed channel flow flows are distinct, the flow in the channels will constantly change. The flow will also be altered if the water level or flow velocity changes. It was found that employing the Pitot Tube Portable yielded findings identical to those calculated by other methods. A water transfer system is made up of natural or artificial structures via which water is moved from one site to another. The carrier building may be open or closed, depending on whether you want to utilize it as a shipping or receiving location. An open channel with a relatively narrow opening at the top is known as an open conduit. The speed data collection technique is carried out vertically, with a review point as illustrated above. The velocity of the flow was measured using a Pitot Tube Portable Automatic tool. The results are entered into the Froude number (fr) after each review point to determine the type of velocity flow at each Review point. The normal flow velocity distribution pattern emerges at the measurement sites of 450 cm, 500 cm, and 550 cm.

Analysis of Cerebral Vasospasm in a Murine Model of Subarachnoid Hemorrhage with High Frequency Transcranial Duplex Ultrasound

The aim of this manuscript is to present a sonography-based method that allows in vivo imaging of blood flow in cerebral arteries in mice. We demonstrate its application to determine changes in blood flow velocities associated with vasospasm in murine models of subarachnoid hemorrhage (SAH).

Hydrodynamic modeling to evaluate the influence of inland navigation channel training works on fish habitats in the Upper Yellow River

The need to balance inland waterway engineering with river ecological integrity has attracted increasing attention from waterway engineers. Quantitative tools for evaluating the effects of waterway engineering on fish habitat serve as an effective basis for engineering design assessment and improvement. A tourism waterway construction project along the Upper Yellow River (UYR) is located within a core area of the National Aquatic Germplasm Resources Conservation Area. The evaluation of the habitat design performance of waterway training works (which is similar to the term of Inland navigation channel training works, it involves structures and measures that reshape a river channel to create reliable depths and widths for safe and dependable vessel transit.), however, are rare in China. To evaluate the effects of waterway engineering on fish habitats and improve engineering design, we evaluated the influence of waterway training works on habitats for endangered adult Platypharodon extremus (Han et al., 2016) by applying a 2D hydrodynamic model to three scenarios: with and without training works and with improved training works. The simulations reproduced changes in flow velocity and water depth within the navigation discharges range. The size and distribution of suitability indexes of water depth and flow velocity and their combined habitat suitability index were employed to assess available habitats for adult Platypharodon extremus to evaluate the influence of engineering actions.The simulations show that the habitat losses due to waterway training works in the study reach can be restored by introducing eco-friendly concepts into training structures and dredging design. Habitat availability for adult Platypharodon extremus has been reduced after waterway training works, especially at low and moderate discharges (the percentage of available area decreased from 13.48% to 11.69% at designed lowest navigation discharge). Habitat availability is much less sensitive to training works at high discharge than at moderate levels. The available habitat can be restored to at least 97% of its original level through the introduction of eco-friendly conceptual designs (the percentage of available area at designed lowest navigation discharge can be recovered to 13.41%).

Analysis of cerebral blood flow entropy while listening to music with emotional content

Objective. Music is one of the most sublime stimuli that human beings can experience. Despite being just an acoustic wave that exerts little physical influence on a subject, it triggers profound changes in emotions and physiological states. This study explores the possibility of detecting subtle changes in cerebral blood flow velocity in response to emotional reactions produced by different musical stimuli using multiscale entropy analysis. Approach. Cerebral blood flow signals were successfully recorded for 16 subjects while performing five different musical tasks. The entropy of each signal was estimated using multiscale sample entropy. Main results. This method has been shown to be capable of revealing the complexity of the internal dynamics of different physiological systems, which cannot be appreciated with classic approaches based on entropy on a single scale. Significance. Significant differences in entropy were found between two of the tasks, which suggests that intense cognitive activities with emotional content cause a decrease in the entropy of cerebral haemodynamics.

Torque and Power Testing of the Pelton Turbine

Energy sources that can be renewed in Indonesia according to Asean energy sources, one of which is microhydro that uses water as a source of energy from a turbine. The potential energy of water is converted into kinetic energy in the nozzles. The water coming out of the nozzle that has a high speed hits the turbine blade. After hitting the blade direction the flow velocity changes so that the momentum changes (impulses) so that the turbine wheel will rotate. Pelton Turbines are impulse turbines which consist of a set of road blades that are rotated by a jet of water sprayed from one or more devices called nozzles. Pelton Turbine is one of the most efficient and suitable types of water turbines used for high head and small flow discharge. Pelton turbines have several advantages including turbine efficiency which is relatively stable at various changes in flow discharge. The purpose of this writing is to find out and provide insight into the torque and power of the Pelton turbine and the effect on the valve openings that are varied.

Retrobulbar blood flow in rat eyes during acute elevation of intraocular pressure

Most studies of the effect of acute elevation of intraocular pressure (IOP) on ocular blood-flow have utilized optical coherence tomography (OCT) to characterize retinal and choroidal flow and vascular density. This study investigates the effect of acute IOP elevation on blood flow velocity in the retrobulbar arteries and veins supplying and draining the eye, which, unlike the retinal and choroidal vasculature, are not directly compressed as IOP is increased. By cannulation of the anterior chamber of 20 Sprague-Dawley rats, we increased IOP in 10 mmHg steps from 10 to 60 mmHg and returned to 10 mmHg. After 1 min at each IOP (and 3 min after return to 10 mmHg), we acquired 18 MHz plane-wave ultrasound data at 3000 compound images/sec for 1.5 s. We produced color-flow Doppler images by digital signal processing of the ultrasound data, identified retrobulbar arteries and veins, generated spectrograms depicting flow velocity over the cardiac cycle and characterized changes of vascular density and perfusion in the orbit overall. Systolic, diastolic and mean velocities and resistive and pulsatile indices were determined from arterial spectrograms at each IOP level. Baseline mean arterial and mean venous velocities averaged 30.9 ± 10.8 and 8.5 ± 3.3 mm/s, respectively. Arterial velocity progressively decreased and resistance indices increased at and above an IOP of 30 mmHg. Mean arterial velocity at 60 mmHg dropped by 55% with respect to baseline, while venous velocity decreased by 20%. Arterial and venous velocities and resistance returned to near baseline after IOP was restored to 10 mmHg. Both vascular density and orbital perfusion decreased with IOP, but while perfusion returned to near normal when IOP returned to 10 mmHg, density remained reduced. Our findings are consistent with OCT-based studies showing reduced perfusion of the retina at levels comparable to retrobulbar arterial flow velocity change with increased IOP. The lesser effect on venous flow is possibly attributable to partial collapse of the venous lumen as volumetric venous outflow decreased at high IOP. The continued reduction in orbital vascular density 3 min after restoration of IOP to 10 mmHg might be attributable to persisting narrowing of capillaries, but this needs to be verified in future studies.

Impact of shape on particle detachment in linear shear flows

Transport and detachment of colloidal particles with irregular shapes occur in geology, environmental, and water-resource engineering. We investigated the effect of shape and aspect ratio on the detachment of non-spherical microparticles attached to a plane substrate, in Couette linear shear flow, under favourable conditions. The detachment conditions were determined by the mechanical equilibrium of drag, lift, gravity and adhesion forces acting on the particle. Drag and lift were evaluated using Computational Fluid Dynamics (CFD), introducing the shape-dependent corrections into traditional formulae for spherical particles. The adhesive particle–surface force is determined by the Surface Element Integration (SEI) method, which also corrects the classical DLVO expression. The forces exerted on spheroids and cylinders can significantly differ from spheres and their detachment exhibit non-monotonic dependencies with aspect ratio. Direct visualisation experiments were performed by piecewise-constant change of flow velocity and the observed detachment were in good agreement with the mechanical-equilibrium based predictions.

Experimental investigation on gliding arc plasma ignition in double-head swirling combustor

The ignition and flame stabilization of an aeroengine have been the key problem of research under extreme conditions such as low temperature, low pressure, and high altitude. The gliding arc discharge is identified as having the potential to expand lean ignition limit and blow out limit. In this paper, the instantaneous power of the gliding arc and the CH⁎ chemiluminescence imaging of the ignition process are investigated in the double-head swirling combustor. The results show that the averaged power of the gliding arc is reduced in a low-pressure environment, and the three-channel gliding arc (3-GA) is more sensitive to the changes of inlet flow velocity. At the low-temperature environment range from T=228 K to T=288 K, the averaged power of the single-channel gliding arc (SGA) is only 211 W, while the averaged power of the 3-GA is 535 W, nearly 153% higher than that of the SGA. As the altitude increases, the averaged power of gliding arc decreases. As the ambient pressure in the combustion chamber decreases, the blow-out limit of the combustor is correspondingly broadened under the excitation of the gliding arc. The fuel-air ratio (FAR) is negatively correlated with the averaged power. Except at P=70-90 kPa, the combustion chamber excited by the 3-GA exhibits a wider lean ignition limit. The FAR increases with the altitude increases. Compared with traditional spark igniter, the lean ignition limit of the SGA is broadened by about 67%. The lean ignition limit is broadened by about 20% on average by the 3-GA, especially by 31% at an altitude of 6 km. The lean blow-out limit is broadened by 18.2% on average, especially by 25% at ground state. The success of gliding arc ignition is related to whether the excited flame propagates into the main recirculation area to form a resident flame in the double-head swirling combustion chamber. The ignition delay time of the SGA is less than that of the 3-GA, which is related to the fact that the SGA is stretched further downstream of the combustion chamber under the action of inlet air flow, and the energy of a single channel in 3-GA is less than the centralized energy of the SGA.

Are aquatic Hemiptera good indicators of environmental river conditions?

Aquatic Hemiptera are barely used as "indicators" because they are considered ubiquitous organisms of great dispersal capacity and a wide range of occupied habitats. Here, we address this topic analyzing the environmental factors determining the distribution of the species found in a northeastern Moroccan basin with a strong altitudinal gradient, as well as their capability of establishing assemblages and the niche breadth for each species. Between 2014 and 2017, we sampled 55 contrasted sites representing the heterogeneity of aquatic ecosystems in the study area, where we collected a total of 27 species. The relationships between the species and environmental variables were evaluated using the STATICO methods, showing a distribution mainly influenced by the changes in flow velocity and conductivity. The Bray–Curtis dissimilarity index identified four assemblages: (a) a running species group in upper freshwater streams; (b) a middle stream group preferring less flow velocity and moderate mineralization; (c) a third group, near to the mouth, occupying moderate running or lentic brackish waters; and (d) a fourth group linked with hypersaline standing environments. The use of Indicator Species Analysis (IndVal) found few but representative species for each assemblage. The OMI applied showed that the majority of species had a high niche breadth and, consequently, a low specialization. Our results highlighted the overall poor habitat requirement and very ubiquitous character of most species found. Only some of them, mainly the endemism Aphelocheirus pemae, can be considered key for biodiversity conservation purposes because of their low niche breadth and high indicator value.

Effects of meteorological factors and groundwater depths on plant sap flow velocities in karst critical zone

Determining water supply intensity of fracture/conduits is one of the difficulties involved in the research of plant transpiration water consumption in the Karst Critical Zone (KCZ). Our aims were to evaluate the effect of groundwater depth on plant sap flow velocities in KCZ. Thus, four sampled plots with different groundwater depth (GD) in boreholes KCZ7 (4 to 10 m GD), KCZ5 (2 to 9 m GD), KCZ1 (0 to 8 m GD) and KCZ3 (2 to 5 m GD), were selected, and the plant stem sap flow velocity in each plot were also monitored continuously and automatically using heat ratio techniques. The daily sap flow flux of Toona sinensis varied between 0.35 kg d−1 in KCZ3 and 1.50 kg d−1 in KCZ1. Photosynthetically active radiation (PAR), vapor pressure deficit (VPD), and gust velocity (ZWS) were the primary meteorological factors that determined the sap flow velocity of T. sinensis, which contributed to a regression equation, while the influence of GD on sap flow was complex. Most of the sap flow velocity had no obvious significant correlation with the GD; however, the sap flow velocity in four different GD showed significant differences (P < 0.05). Unit sap flow velocity changes induced by unit GD changes (Kv) in KCZ7 and KCZ1 samples was faster than that of other samples. In brief, the sap flow velocity was mainly affected by the PAR and VPD in KCZ7, KCZ5 and KCZ1 because of the sufficient epikarst water, while the sap flow velocity in KCZ3 was mainly affected by the rock water content. The karst aquifer medium and GD was the main factors causing the difference sap flow velocity in the four sample plots. This finding indicated that KCZ aquifer medium structure may have an important influence on plant water utilization.

Introduction of precordial Doppler ultrasound to confirm correct peripheral venous access during general anesthesia in children: A preliminary study.

Delayed identification of infiltration and dysfunction of peripheral intravenous (PIV) access can lead to serious consequences during general anesthesia in children. This preliminary study aimed to describe the application of precordial Doppler ultrasound during general anesthesia in children to detect and confirm the correct PIV access and to evaluate the accuracy of this method. This was a single-center, preliminary study that was conducted in children (<18 years) who were scheduled for elective surgeries between October 2019 and March 2020. Rater anesthesiologists judged the change in precordial Doppler sound (S test) before and after injection of 0.5 mL/kg of normal saline (NS) via PIV. Blood flow velocity before and after NS injection was recorded, and multiple cutoff points were set to analyze the accuracy of detecting the infiltration and dysfunction of PIV catheter (V test). The total incidence of peripheral infiltration and dysfunction of PIV catheter was 7/512 (1.4%). In the S test, the sensitivity, specificity, positive and negative likelihood ratios, and area under the receiver-operating characteristic curves (AUCs) were 5/7 (71.4%; 95% confidence interval [CI], 29.0%-96.3%), 490/505 (97.0%; 95% CI, 95.1%-98.3%), 24.0, 0.29, and 0.84, respectively. The V test showed that the reasonable threshold of blood flow velocity change was 1.0 m/s, with sensitivity, specificity, positive and negative likelihood ratios, and AUC of 4/7 (57.1%; 95% CI, 18.4%-90.1%), 489/505 (96.8%; 95% CI, 94.9%-98.2%), 18.0 and 0.44, and 0.84, respectively. This preliminary study demonstrated that precordial Doppler ultrasound is a feasible, easy-to-use, and noninvasive technique with good accuracy to confirm the correct PIV access during general anesthesia in children. However, its accuracy requires further evaluation.

Flow Velocity Change of David Glacier, East Antarctica, from 2016 to 2020 Observed by Sentinel-1A SAR Offset Tracking Method

This study measures the change of ice flow velocity of David Glacier, one of the fast-moving glaciers in East Antarctica that drains through Drygalski Ice Tongue. In order to effectively observe the rapid flow velocity, we applied the offset tracking technique to Sentinel-1A SAR images obtained from 2016 to 2020 with 36-day temporal baseline. The resulting velocity maps were averaged and the two relatively fast points (A1 and A2) were selected for further time-series analysis. The flow velocity increased during the Antarctic summer (around December to March) over the four years’ observation period probably due to the ice surface melting and reduced friction on the ice bottom. Bedmap2 showed that the fast flow velocities at A1 and A2 are associated with a sharp decrease in the ice surface and bottom elevation so that ice volumetric cross-section narrows down and the crevasses are being created on the ice surface. The local maxima in standard deviation of ice velocity, S1 and S2, showed random temporal fluctuation due to the rotational ice swirls causing error in offset tracking method. It is suggested that more robust offset tracking method is necessary to incorporate rotational motion.

Geodetic point surface mass balances: a new approach to determine point surface mass balances on glaciers from remote sensing measurements

Abstract. Mass balance observations are very useful to assess climate change in different regions of the world. As opposed to glacier-wide mass balances which are influenced by the dynamic response of each glacier, point mass balances provide a direct climatic signal that depends on surface accumulation and ablation only. Unfortunately, major efforts are required to conduct in situ measurements on glaciers. Here, we propose a new approach that determines point surface mass balances from remote sensing observations. We call this balance the geodetic point surface mass balance. From observations and modelling performed on the Argentière and Mer de Glace glaciers over the last decade, we show that the vertical ice flow velocity changes are small in areas of low bedrock slope. Therefore, assuming constant vertical velocities in time for such areas and provided that the vertical velocities have been measured for at least 1 year in the past, our method can be used to reconstruct annual point surface mass balances from surface elevations and horizontal velocities alone. We demonstrate that the annual point surface mass balances can be reconstructed with an accuracy of about 0.3 m of water equivalent per year (m w.e. a−1) using the vertical velocities observed over the previous years and data from unmanned aerial vehicle images. Given the recent improvements of satellite sensors, it should be possible to apply this method to high-spatial-resolution satellite images as well.

Study of hydraulic gradient and velocity changes of unsteady flow through coarse porous media

ABSTRACT To calculate the hydraulic gradient (i) in steady – non Darcy regimes, the validity of the binomial relationship is confirmed using dimensional analysis and Navier-Stokes equations. According to St. Venant equations, the experimental data used in the present study are of the diffusion wave type and the changes in flow depth (h) in terms of changes in flow rate (Q) or flow velocity (V) (flow-depth curve) are in the Loop form. In other words, for a value of V, there are two different values for h, and given the relationship between i and h, for each value of V, there are two different values for i that in the ascending area of the input hydrograph, the value of i is greater than its descending area. For this reason, in the present study, in order to use the binomial relation in unsteady flow conditions, for each of the above ascending and descending areas, a different value for the coefficients a and b of the binomial relation has been optimized using the Particle Swarm Optimization (PSO) algorithm. The results show that if instead of using a constant value for the coefficients a, b, two different values are used for the mentioned coefficients, the improvement of the values of the sum of the absolute value deviations (SAD) and the sum of the squared deviation (SSQ) for Small grain size are 39% and 47%, respectively, for Medium grain size are 50 and 74, respectively, and for large grain size are 62% and 80%, respectively.

Hemodynamic effects of intracranial aneurysms from stent-induced straightening of parent vessels by stent-assisted coiling embolization.

Straightening of parent vessels happens for stent-assisted coiling embolization (SACE) treatment of intracranial aneurysms. This study aims to investigate aneurysmal hemodynamic modifications caused by stent-induced vessel straightening. Stent and coil deployments of a SACE-treated distal bifurcation aneurysm by finite element method were performed first with the preoperative (not straightened, NS) and postoperative (straightened, S) vessel models respectively. Computational fluid dynamics were then performed for eight models, including (I) NS only model, (II) NS+stent model, (III) NS+coils model, (IV) NS+stent+coils model, (V) S only model, (VI) S+stent model, (VII) S+coils model, and (VIII) S+stent+coils model. Finally, changes in aneurysmal flow velocity, isovelocity surface and wall shear stress (WSS) were analyzed qualitatively and quantitatively. The flow was less in the S models than that in the corresponding NS models. Coils blocked most of the flow into the aneurysm sac in both NS models and S models and vessel straightening had more profound effect on the high aneurysmal flow volume reduction than coiling, while stenting generated adverse effect on flow reduction. Taking the NS only model as baseline (100%), the sac-averaged velocities of models II to VIII were 112%, 36%, 42%, 45%, 39%, 12%, 13%, and high flow volumes were 119%, 21%, 30%, 10%, 8%, 3%, 3%, while the sac-averaged WSSs were 106%, 37%, 44%, 41%, 35%, 17% and 24%, respectively. Stent-induced vessel straightening combined coil embolization has the best performance in hemodynamic modifications and may reduce the recurrence rate, whereas stenting may generate adverse effect on hemodynamic alterations.

Flow velocity quantification by exploiting the principles of the Doppler effect and magnetic particle imaging

Changes in blood flow velocity play a crucial role during pathogenesis and progression of cardiovascular diseases. Imaging techniques capable of assessing flow velocities are clinically applied but are often not accurate, quantitative, and reliable enough to assess fine changes indicating the early onset of diseases and their conversion into a symptomatic stage. Magnetic particle imaging (MPI) promises to overcome these limitations. Existing MPI-based techniques perform velocity estimation on the reconstructed images, which restricts the measurable velocity range. Therefore, we developed a novel velocity quantification method by adapting the Doppler principle to MPI. Our method exploits the velocity-dependent frequency shift caused by a tracer motion-induced modulation of the emitted signal. The fundamental theory of our method is deduced and validated by simulations and measurements of moving phantoms. Overall, our method enables robust velocity quantification within milliseconds, with high accuracy, no radiation risk, no depth-dependency, and extended range compared to existing MPI-based velocity quantification techniques, highlighting the potential of our method as future medical application.

Computed tomography assessment of soil and sediment porosity modifications from exposure to an acid copper sulfate solution

Mine spills, like acidified copper sulfate solutions, are known for the contaminating effects in soils and sediments, chemically altering them. However, little is known about the physical effects of this process. Therefore, we investigated the response of the soil and sediments porosity to the infiltration of an acid copper sulfate solution (ACSS) generated for mining purposes. The samples used consisted of intact/undisturbed soil and sediment columns extracted in the upper Rio Sonora basin, located in northern Mexico in the state of Sonora, where extensive mining activity has been carried out since 1880's. Three infiltration and solute transport experiments were conducted to monitor the changes in pH, electrical conductivity (EC) and flow velocity in the collected leachate. Computed X-Ray Tomography was used to microscopically analyze a series of soil porosity images before and after each irrigation with ACSS. We observed that the interactions of soil/sediment matrices with ACSS, promoted changes in the flow velocity, which can be related to the modification of the original porosity. The computed X-Ray Tomography showed that the passage of the ACSS through the soil and sediment caused different effects in both matrices: (1) a decrease in the number and size of pores in the soil column and (2) an increase in the number and size of pores in the sediment, showing that the passage of the solution in both matrices had opposite effects, causing a decrease in soil porosity as a possible response to the presence of suspended particles related to the ACSS, and the formation of new minerals that caused the sealing of pores in the soil and the erosion of the walls of the pores in the sediment creating preferential flows. This work shows that soils and sediments that interact with the ACSS are not only affected chemically, but also that there may appear modifications in porosity, leading to study also the physical effects that occur in sites affected by this type of events.

Visualization of brain microvasculature and blood flow in vivo: Feasibility study using confocal laser endomicroscopy.

Qualitative and quantitative analyses of blood flow in normal and pathologic brain and spinal cord microvasculature were performed using confocal laser endomicroscopy (CLE). Blood flow in cortical, dural, and spinal cord microvasculature was assessed in vivo in swine. We assessed microvasculature under normal conditions and after vessel occlusion, brain injury due to cold or surgical trauma, and cardiac arrest. Tumor-associated microvasculature was assessed in vivo and ex vivo in 20 patients with gliomas. We observed erythrocyte flow in vessels 5-500µm in diameter. Thrombosis, flow arrest and redistribution, flow velocity changes, agglutination, and cells rolling were assessed in normal and injured brain tissue. Microvasculature in in vivo CLE images of gliomas was classified as normal in 68% and abnormal in 32% of vessels on the basis of morphological appearance. Dural lymphatic channels were discriminated from blood vessels. Microvasculature CLE imaging was possible for up to 30minutes after a 1mg/kg intravenous dose of fluorescein. CLE imaging allows assessment of cerebral and tumor microvasculature and blood flow alterations with subcellular resolution intraoperative imaging demonstrating precise details of real-time cell movements. Research and clinical scenarios may benefit from this novel intraoperative in vivo microscopic fluorescence imaging modality.

Reclamation-induced tidal restriction increases dissolved carbon and greenhouse gases diffusive fluxes in salt marsh creeks

Intertidal creeks play an important role in transporting nutrients between coastal ecosystems and ocean. Reclamation is a predominant anthropogenic disturbance in coastal regions; however, the influence of reclamation on carbon and nitrogen species and greenhouse gas (GHG) fluxes in creek remains unclear. In a subtropical salt marsh of eastern China, the seasonal patterns of dissolved carbon (DOC, DIC, CO2, and CH4) and inorganic nitrogen (NH4+-N, NO2−-N, and NO3−-N and N2O) species, and the diffusive fluxes of CO2, CH4, and N2O, were compared between the natural tidal creeks and the reclaimed creeks. Due to notably changed hydrological and biological conditions in the reclaimed creeks, concentrations of all dissolved carbon species, NH4+-N and NO2−-N increased significantly by 60.2–288.2%, while NO3−-N and N2O decreased slightly, compared to the natural tidal creeks. DIC and NO3−-N were the primary components of the total dissolved carbon and inorganic nitrogen in both creek types; however, their proportions decreased as a result of elevated DOC, CO2, CH4, NH4+-N, and NO2−-N following reclamation. Significantly higher global warming potential (0.58 ± 0.15 g CO2-eq m−2 d−1) was found in the reclaimed creeks, making them hotspot of greenhouse effects, compared to the natural tidal creeks. Our results indicated that changes in flow velocity, salinity, Chlorophyll a, and pH were the main factors controlling the dissolved carbon and nitrogen and consequent GHG emissions, due to reclamation. This study is helpful in understanding of carbon and nitrogen sink-source shifts resulting from land use changes in coastal wetlands.