Sediment Flux Research Articles

Combining hillslope erosion and river connectivity models to assess large scale fine sediment transfers: Application over the Rhône River (France)

AbstractSediment connectivity at the catchment scale includes the processes linking sediment sources, sinks and the river outlet. Soil erosion models usually estimate yields without considering riverine processes or human infrastructure that may affect sediment connectivity. Quantifying these processes at a large scale is a determinant of understanding sediment transfers from continental lands to marine ecosystems. This study tries to fill this gap by coupling the soil erosion model WaTEM/SEDEM (WS) with the riverine connectivity tool CASCADE to quantify sediment fluxes in the Rhône watershed. The coupling returned a good fit, with deviations of −51.7%. WS alone predicts the exported fluxes better with a deviation of −34.9%. Nevertheless, this paper shows the importance of considering connectivity and transport capacity to develop a more realistic representation of fine sediment dynamics at a large scale. However, connectivity tools depend on the quality of the models (soil erosion and hydrology) and the geomorphological data on which they depend, which is a limiting factor in large‐scale studies.

Can restoring water and sediment fluxes across a mega-dam cascade alleviate a sinking river delta?

Hydropower, although an attractive renewable energy source, can alter the flux of water, sediments, and biota, producing detrimental impacts in downstream regions. The Mekong River illustrates the impacts of large dams and the limitations of conventional dam regulating strategies. Even under the most optimistic sluicing scenario, sediment load at the Mekong Delta could only recover to 62.3 ± 8.2 million tonnes (1 million tonnes = 109 kilograms), short of the (100 to 160)-million tonne historical level. Furthermore, unless retrofit to reroute sediments, the dams are doomed to continue trapping sediment for at least 170 years and thus starve downstream reaches of sediment, contributing to the impending disappearance of the Mekong Delta. Therefore, we explicitly challenge the widespread use of large dead storages-the portion of the reservoirs that cannot be emptied-in dam designs. Smaller dead storages can ease sediment starvation in downstream regions, thereby buffering against sinking deltas or relative sea level rises.

Ideas and perspectives: Human impacts alter the marine fossil record

Abstract. The youngest fossil record is a crucial source of data documenting the recent history of marine ecosystems and their long-term alteration by humans. However, human activities that reshape communities and habitats also alter sedimentary and biological processes that control the formation of the sedimentary archives recording those impacts. These diverse physical, geochemical, and biological disturbances include changes in sediment fluxes due to the alteration of alluvial and coastal landscapes, seabed disturbance by bottom trawling and ship traffic, ocean acidification and deoxygenation, removal of native species, and introduction of invasive ecosystem engineers. These novel processes modify sedimentation rates, the depth and intensity of sediment mixing, the pore-water saturation state, and the preservation potential of skeletal remains – the parameters controlling the completeness and spatiotemporal resolution of the fossil record. We argue that humans have become a major force transforming the nature of the marine fossil record in ways that can both impede and improve our ability to reconstruct past ecological and climate dynamics. A better understanding of the feedback between human impacts on ecosystem processes and their preservation in the marine fossil record offers new research opportunities and novel tools for interpreting geohistorical archives of the ongoing anthropogenic transformation of the coastal ocean.

Contribution of high turbidity to tidal dynamics in a curved channel in Zhoushan Islands, China

The curved tidal channel, Luotou Deep-water Navigational Channel, is the main channel of the Ningbo Zhoushan Port, which is ranked first in the world. Tidal dynamics in the channel are spatially and temporally asymmetric. In this study, the three-dimensional tidal dynamics in the channel were analyzed using field data and simulated using FVCOM. The results show that the tides in the channel flood/ebb along the northern/southern bank near the bottom/surface layer and these asymmetries are due to the imbalanced Coriolis force, centrifugal force, sea-level gradient, and density gradient. Residual current velocity peaks (0.7 m/s) in the middle of the channel as the same distribution as sediment flux. There are two high turbidity zones (>4 kg/m3) which are northern at flood than at an ebb in the channel. The drag reduction effect of fluid mud enhances the lateral circulation, which is strong near the Chuanshan Peninsula and frictional dissipation plays an important role in it. The presence of suspended sediment changes the contribution of acceleration terms through impacting density and bottom friction, and the centrifugal force term has the largest increases. This study provides the foundation for the morphology evolution and harbor management of macro-tidal turbid coastal zones. Highlights A baroclinic model was built to study the tidal dynamics in macro-tidal turbid Zhoushan Islands. Asymmetric tides and lateral circulation occur in the Luotou Deep-water Navigational Channel (DNC). Mechanism of lateral circulation depends on tidal phases and locations in the DNC. Sediment impacts water density and drag coefficient, and then changes currents and sediment fluxes in the DNC.

A Quantitative Provenance Analysis (QPA) Approach to Quantify Controls on Sediment Generation and Sediment Flux in the Upper Reaches of the Magdalena River (Colombia): 1. Natural and Anthropic Controls on the Sand Fraction

AbstractThis study investigates the upper Magdalena river basin (Colombia), which is characterized by tectonic activity, tropical climate, heterogeneous lithological assemblages, and anthropic influence. It aims to comprehend factors controlling sediment generation, flux, and composition by incorporating petrographic data from 27 recent fluvial samples along with geochemistry, geomorphological parameters, historical precipitation, land cover, landsliding and suspended sediment load data. The analysis shows mismatches between sand composition and drainage lithology distribution. A new set of endmember mixing models is presented, quantifying the impacts of erodibility, sand generation potential (related to lithology), and sediment connectivity between hillslopes and river outlets (related to geomorphology). Results show enhanced sediment generation from sedimentary rocks (up to 40%) due to high erodibility, and decreased sediment flux from low‐ to medium‐grade metamorphic rocks (up to 60%) due to controlling morphometric parameters. Overrepresentation of plutonic and high‐grade metamorphic rocks and underrepresentation of volcanic rocks (up to 100%) are controlled by mineralogical and textural parameters. Enhanced landsliding activity in areas with volcanic activity occasionally overshadows basin‐wide compositional trends driven by morphological and lithological characteristics, as it controls rare overrepresentation of volcanic and low‐grade metamorphic detritus in the sand fraction. Sediment retention by hydroelectric dams significantly decreases suspended sediment flux by 30%, while deforestation plays a minor role in sediment flux. This study underscores the importance of coupling sediment generation, geomorphology and the distribution of stochastic events related to seismic activity in any sediment production‐focused study and for developing numerical models in Quantitative Provenance Analysis (QPA).

Century‐Long Records of Sedimentary Input on a Caribbean Reef From Coral Ba/Ca Ratios

AbstractCoral reef ecosystems are delicately balanced and are thus prone to disruption by stressors such as storms, disease, climate variability and natural disasters. Most tropical coral populations worldwide are now in rapid decline owing to additional anthropogenic pressures, such as global warming, ocean acidification and a variety of local stressors. One such problem is the addition of excess sediment and nutrients flux to reefs from increased soil erosion from land use changes. Here we present century‐long Ba/Ca records from two Siderastrea siderea colonies as a proxy for local riverine discharge and sediment flux to the southern Mesoamerican Barrier Reef System (MBRS). The coral colonies have linear extension trends, which can be seen as a first‐order indicator for coral health and response. The coral colony that exhibits a decline in linear extension rate from the forereef of the MBRS, mainly receives riverine input from Honduras, whilst the coral from the backreef, which does not exhibit a decline in extension rate, primarily receives riverine input from more sparsely populated regions of Belize. Coral Ba/Ca increased (>70%) through time in the forereef colony, while the backreef colony showed little long‐term increase in Ba/Ca over the last century. Our results suggest that increasing sediment supply may have played a role in the decline of forereef skeletal extension in the southernmost MBRS region, likely stemming from increasing land‐use changes in Honduras.

A Quantitative Provenance Analysis (QPA) Approach to Quantify Controls on Sediment Generation and Sediment Flux in the Upper Reaches of the Magdalena River (Colombia): 2. Lithological Control on Contribution to Silt‐ to Clay‐Sized Fractions

AbstractThe composition of 27 fluvial silt and clay sediments was used in this study to identify and quantify the processes in the upper valley of the Magdalena river in South Colombia. The combination of seismic activity, intense precipitation, and landsliding resulted in limited chemical weathering and a very efficient transfer of weathered products to the transfer zone of both tributary rivers and the main trunk. Inputs from plutonic, high‐grade metamorphic, volcanic, and low‐ to medium‐grade metamorphic lithologies vary in coarse silt‐sized versus fine silt‐ and clay‐sized sediments, reflecting inherited textural parameters and mineralogy. Plutonic and high‐grade metamorphic rocks mostly produce sand‐sized sediments, up to two times more than coase silt and up to 10 times more than fine silt to clay. The prevalence of siltstone in the area enhances the contribution of sedimentary rocks to fine silt and clay (up to 50% higher than to sand). Volcanic rocks mainly produce coarse silt (up to 2.5 times more than sand). Low‐grade metamorphic detritus is enriched in silt and clay (up to 5–7 times). These findings highlight the critical role of lithology in regulating sediment generation. The study's approach can establish or modify factors modeling lithological control on suspended sediment flux, such as in the BQART equation.

Lake Surface Water Temperature in high altitude lakes in the Pyrenees: Combining satellite with monitoring data to assess recent trends

Lake Surface Water Temperature (LSWT) influences critical bio-geological processes in lake ecosystems, and there is growing evidence of rising LSWT over recent decades worldwide and future shifts in thermal patterns are expected to be a major consequence of global warming.At a regional scale, assessing recent trends and anticipating impacts requires data from a number of lakes, but long term in situ monitoring programs are scarce, particularly in mountain areas. In this work, we propose the combined use of satellite-derived temperature with in situ data for a five-year period (2017–2022) from 5 small (<0.5km2) high altitude (1880–2680 masl) Pyrenean lakes. The comparison of in situ and satellite-derived data in a common period (2017–2022) during the summer season showed a notably high (r = 0.94, p < 0.01) correlation coefficient, indicative of a robust relationship between the two data sources. The root mean square errors ranged from 1.8 °C to 3.9 °C, while the mean absolute errors ranged from 1.6 °C to 3.6 °C.We applied the obtained in situ-satellite eq. (2017–2022) to Landsat 5, 7 and 8/9 data since 1985 to reconstruct the summer surface temperature of the five studied lakes with in situ data and to four additional lakes with no in situ monitoring data. Reconstructed LSWT for the 1985–2022 showed an upward trend in all lakes. Moreover, paleolimnological reconstructions based on sediment cores studies demonstrate large changes in the last decades in organic carbon accumulation, sediment fluxes and bioproductivity in the Pyrenean lakes.Our research represents the first comprehensive investigation conducted on high mountain lakes in the Pyrenees that compares field monitoring data with satellite-derived temperature records. The results demonstrate the reliability of satellite-derived LSWT for surface temperatures in small lakes, and provide a tool to improve the LSWT in lakes with no monitoring surveys.

Spatiotemporal patterns and deposition of organophosphate esters (OPEs) in air, foliage and litter in a subtropical forest of South China

Recent studies revealed the un-negligible impact of airborne organophosphate esters (OPEs) on phosphorus (P)-limited ecosystems. Subtropical forests, the global prevalence P-limited ecosystems, contain canopy structures that can effectively sequester OPEs from the atmosphere. However, little is known about the behavior and fate of OPEs in subtropical forest ecosystem, and the impact on the P cycling in this ecosystem. OPE concentrations in the understory air (at two heights), foliage, and litterfall were investigated in a subtropical forest in southern China. The median ∑OPE concentrations were 3149 and 2489 pg/m3 in the upper and bottom air, respectively. Foliage exhibited higher ∑OPE concentrations (median = 386 ng/g dry weight (dw)) compared to litter (median = 267 ng/g dw). The air OPE concentrations were ordered by broadleaved forest > mixed forest > coniferous forest, which corresponds to the results of canopy coverage or leaf area index. The spatial variation of OPEs in foliage and litter was likely caused by the leaf surface functional traits. Higher OPE concentrations were found in the wet season for understory air while in the dry season for foliage and litter, which were attributed to the changes in emission sources and meteorological conditions, respectively. The inverse temporal variation suggests the un-equilibrium partitioning of OPEs between leaf and air. The OPE concentrations during the litter-incubation presented similar temporal trends with those in foliage and litter, indicating the strong interaction of OPEs between the litter layer and the near-soil air, and the efficient buffer of litter layer played in the OPEs partitioning between soil and air. The median OPEs-associated P deposition fluxes through litterfall were 270, 186, and 249 μg P/m2·yr in the broadleaved, mixed, and coniferous forests, respectively. Although the fluxes accounted for approximately 0.2% of the total atmospheric P deposition, their significance to this P-limited ecosystem may not be negligible.

Quantity and quality characteristics of DOM loss in sloping cropland under natural rainfall in Southwestern China

Rainfall events lead to dissolved organic matter (DOM) loss in sloping cropland, resulting in a high risk of soil carbon emissions and water pollution. However, limited studies have concentrated on the quality of DOM during different loss pathways in sloping cropland. In this study, the characteristics of DOM loss were explored during different loss pathways (surface runoff, interflow (0–20 cm), interflow (20–40 cm), and sediment) under different slope gradients (10° and 15°), based on natural rainfall. The results showed that surface runoff was the primary carrier of DOM in the sloping cropland, occupying 33 %-43 % of the total loss flux. The slope gradient significantly increased the DOM loss flux of surface runoff and sediment (p < 0.05). Parallel factor analysis (PARAFAC) analyses indicated that four fluorescent components of DOM were detected in both the runoff and sediment. The humic-like components (C1 and C2) accounted for higher than 70 % of the DOM in surface runoff. The protein-like components (C3 and C4) tended to dominate the DOM in the sediment and accounted for 63.02 %-66.93 %. An increased slope gradient exacerbated hydrophobic carbon loss in runoff. The hydrophobicity and aromaticity of DOM in sediment were higher than those in surface runoff. The molecular weight and bioavailability of DOM in sediment were lower than those in surface runoff. The range of humification index (HIX) was 0.63–0.70, indicating a low degree of DOM humification in sloping cropland. Our study clarified the differences between DOM quantity and quality during different loss pathways, which can provide a theoretical foundation for the effective prevention and control of DOM loss and the sustainable agricultural development of sloping cropland.

Characterization of columnar BiFeO3 thick films prepared by magnetic field-assisted pulsed laser deposition

Polycrystalline BiFeO3 thick films were prepared on Pt/TiO2/SiO2/Si substates by using magnetic field-assisted pulsed laser deposition. Columnar BiFeO3 thick films were successfully obtained with a thickness of 1.8 μm, owing to an oblique incoming flux and high deposition rate by the confinement of the plume under a magnetic field. In the columnar BiFeO3 thick films, a saturated P-E hysteresis loop was obtained at RT, and the remanent polarization (P r ) and coercive field (E c ) were 42 μC cm−2 and 380 kV cm−1, respectively. Also, the piezoelectric response measured by atomic force microscopy showed a butterfly-shaped curve, and the piezoelectric d 33 coefficient was about 50 pm V−1.

Simulation of Bed Change in Al-Musayyab Canal using HEC-RAS Software

This study focuses on the simulation of the bed change and total sediment concentration in the Al-Musayyab Canal, which is a vital irrigation system located in the central region of Iraq, using HEC-RAS V 6.3 software. The 49.5 km canal, with 13 branches, faces challenges from sediment influx originating from the Euphrates River. The primary objective is to analyze sedimentation, erosion patterns, and sediment discharge variations to support effective canal management. Field sampling collected suspended and bed load samples for laboratory tests, providing input data for the sediment transport model. Simulation results show steady flow water surface elevations ranging from 26.32 to 33.16 m.a.s.l, with velocities from 0.24 to 0.98 m/s. Significant sediment deposition and erosion variations are observed as data for 2019 and 2020 are analyzed. Notable changes in the canal's invert levels occurred in both years, with maximum deposition depths reaching 14 cm in 2019 and 21 cm in 2020. Erosion depths ranged from 3 to 15 cm in 2019 and 5 to 25 cm in 2020. The total sediment discharge for 2019 in the Al-Musayyab Canal amounted to 17 tons/day, while 22 tons/day in 2020. 

Improved biomass burning emissions from 1750 to 2010 using ice core records and inverse modeling

Estimating fire emissions prior to the satellite era is challenging because observations are limited, leading to large uncertainties in the calculated aerosol climate forcing following the preindustrial era. This challenge further limits the ability of climate models to accurately project future climate change. Here, we reconstruct a gridded dataset of global biomass burning emissions from 1750 to 2010 using inverse analysis that leveraged a global array of 31 ice core records of black carbon deposition fluxes, two different historical emission inventories as a priori estimates, and emission-deposition sensitivities simulated by the atmospheric chemical transport model GEOS-Chem. The reconstructed emissions exhibit greater temporal variabilities which are more consistent with paleoclimate proxies. Our ice core constrained emissions reduced the uncertainties in simulated cloud condensation nuclei and aerosol radiative forcing associated with the discrepancy in preindustrial biomass burning emissions. The derived emissions can also be used in studies of ocean and terrestrial biogeochemistry.

Adjoint Solver-Based Analysis of Mouth–Tongue Morphologies on Vapor Deposition in the Upper Airway

Even though inhalation dosimetry is determined by three factors (i.e., breathing, aerosols, and the respiratory tract), the first two categories have been more widely studied than the last. Both breathing and aerosols are quantitative variables that can be easily changed, while respiratory airway morphologies are difficult to reconstruct, modify, and quantify. Although several methods are available for model reconstruction and modification, developing an anatomically accurate airway model and morphing it to various physiological conditions remains labor-intensive and technically challenging. The objective of this study is to explore the feasibility of using an adjoint–CFD model to understand airway shape effects on vapor deposition and control vapor flux into the lung. A mouth–throat model was used, with the shape of the mouth and tongue being automatically varied via adjoint morphing and the vapor transport being simulated using ANSYS Fluent coupled with a wall absorption model. Two chemicals with varying adsorption rates, Acetaldehyde and Benzene, were considered, which exhibited large differences in dosimetry sensitivity to airway shapes. For both chemicals, the maximal possible morphing was first identified and then morphology parametric studies were conducted. Results show that changing the mouth–tongue shape can alter the oral filtration by 3.2% for Acetaldehyde and 0.27% for Benzene under a given inhalation condition. The front tongue exerts a significant impact on all cases considered, while the impact of other regions varies among cases. This study demonstrates that the hybrid adjoint–CFD approach can be a practical and efficient method to investigate morphology-associated variability in the dosimetry of vapors and nanomedicines under steady inhalation.

Metal nanowires grown on Cu (100) substrate

We present the growth mechanisms of Ag, Ni, Pd, Co and Fe nanowires on Cu(100) substrate studied by the KMC simulations. It has been allows to found the optimum growth parameters (T, F, θ). Their effects have been discussed in details. The quality of nanowires has been determined by calculating the filling ratio. Our simulations exhibit that the best quality is obtained for Ag NWs. In fact, the maximum filling ratio of Ag NWs is reached for temperature range between 200 and 500 K. The increasing of the deposition flux makes decreases the filling ratio. We get an inverse behavior when the coverage is increased for two different temperatures.

Determining rainwater dissolved organic carbon to reveal atmospheric carbon deposition in China's karst city: Variations, origins, and deposition flux

A large amount of organic carbon (OC) in the atmosphere are transferred to the Earth's surface through dry (40%) and wet (60%) deposition. Therefore, wet deposition is an important physical pathway for the removal of atmospheric OC. Identifying the variations of DOC in wet deposition (rainwater) is essential for clarifying the earth-surface C balance. The present study detected the DOC content in 96 daily rainwater samples collected over an entire year in a karst city, with abundant rainfall in Southwest China. The DOC concentrations varied between 1.03–37.7 mg C L−1, while the VWM value stood at 2.76 mg C L−1, which is similar to the worldwide and Asian averages. The yearly DOC wet deposition flux was calculated as 2.88 g C m−2 yr−1. Both the VWM concentration and flux of rainwater DOC exhibit pronounced seasonal variations and regional differences, primarily controlled by precipitation and the external input of OC. The sources of rainwater DOC were multifaceted, including urban waste emission, agricultural activities, and fossil fuel combustion (especially coal combustion), while the contribution from natural sources was limited. Additionally, the C: N (2.08) ratio of rainwater is significantly lower than the Redfield ratio (6.625), indicating the importance of considering the impact of nutrient components in rainfall on the material cycling of surface water ecosystems. This work will benefit the knowledge of the present status of rainwater DOC and its deposition flux on the karst regional scale and further on a global scale, and contribute to a better understanding of the C geochemical cycle on the territorial system.

An inverse model to correct for the effects of post-depositional processing on ice-core nitrate and its isotopes: model framework and applications at Summit, Greenland, and Dome C, Antarctica

Abstract. Comprehensive evaluation of the effects of post-depositional processing is a prerequisite for appropriately interpreting ice-core records of nitrate concentration and isotopes. In this study, we developed an inverse model that uses archived snow/ice-core nitrate signals to reconstruct primary nitrate flux (i.e., the deposition flux of nitrate to surface snow that originates from long-range transport or stratospheric input) and its isotopes (δ15N and Δ17O). The model was then applied to two polar sites, Summit, Greenland, and Dome C, Antarctica, using measured snowpack nitrate concentration and isotope profiles in the top few meters. At Summit, the model successfully reproduced the observed atmospheric δ15N(NO3-) and Δ17O(NO3-) and their seasonality. The model was also able to reasonably reproduce the observed snowpack nitrate profiles at Dome C as well as the skin layer and atmospheric δ15N(NO3-) and Δ17O(NO3-) at the annual scale. The calculated Fpri at Summit was 6.9 × 10−6 kgN m2 a−1, and the calculated Δ17O(NO3-) of Fpri is consistent with atmospheric observations in the Northern Hemisphere. However, the calculated δ15N(NO3-) of Fpri displays an opposite seasonal pattern to atmospheric observations in the northern mid-latitudes, but it is consistent with observations in two Arctic coastal sites. The calculated Fpri at Dome C varies from 1.5 to 2.2 × 10−6 kgN m−2 a−1, with δ15N(NO3-) of Fpri varying from 6.2 ‰ to 29.3 ‰ and Δ17O(NO3-) of Fpri varying from 48.8 ‰ to 52.6 ‰. The calculated Fpri at Dome C is close to the previous estimated stratospheric denitrification flux in Antarctica, and the high δ15N(NO3-) and Δ17O(NO3-) of Fpri at Dome C also point towards the dominant role of stratospheric origin of primary nitrate to Dome C.

Atmospheric deposition studies of microplastics in Central Germany

AbstractEmission of microplastics (MP) to the atmosphere, airborne transport, and subsequent deposition are now recognized. However, the temporal and spatial resolution of data on MP pollution and knowledge of their atmospheric behaviour and fate is still very limited. Hence, we investigated MP wet and dry deposition in Central Germany and examined the role of weather conditions on MP contamination levels. Monthly samples of dry and wet deposition were taken over an eight-month period (05/2019-12/2019) and analysed by micro-Fourier-Transform Infrared spectroscopy (µFTIR) down to 11 μm particle size and one dry deposition sample was subjected to Raman analysis to determine plastic particles down to a size of 0.5 μm. MP in a size range from 11 μm to 130 μm were detected in all wet deposition samples and in 4 out of 8 dry deposition samples by µFTIR. Polypropylene particles were found most frequently and accounted for 62% and 54% of all particles in wet and dry deposition samples, respectively. Over the eight-month period, wet deposition of MP slightly dominated at the study site and comprised 59% of the total MP deposition. The MP mean total (wet + dry) deposition flux (DF) was 17 ± 14 MP m− 2 day− 1. Extensive Raman analyses of an exemplary dry deposition sample revealed additional plastic particles in the extended size range from 1 to 10 μm resulting in a deposition flux of 207 MP m− 2 day− 1. Our results suggest that MP analysis by µFTIR down to 11 μm may underestimate DF at least by an order of magnitude. More comprehensive studies on submicron plastics and nanoplastics are needed to fully assess air pollution by plastic particles.

Apportionment of NOx and NH3 emission sources in an urban coastal airshed: Insights from stable isotopes and a novel approach to intermittent sources

Inorganic nitrogen (IN) wet deposition flux and emission sources have been intensively investigated over the past two decades with a primary focus in rural areas and large metropolitan cities. Smaller coastal cities are often overlooked in these studies despite a substantial portion of the earth's population inhabiting these regions. Ammonia and NOx emission source apportionment estimations in these studies can be misleading without proper inspection of intermittent source (e.g., biomass burning and lightning) impacts on the airmass of rain events. This study measured the chemical composition (NH4+, NO3−, Cl−, SO42− and pH) and isotopic composition of ammonium and nitrate (δ15N–NH4+, δ15N–NO3-, and δ18O–NO3-) in rainwaters collected in a small coastal city (Corpus Christi, TX, USA) to aid in determining the emission source apportionments of NH3 and NOx. A novel approach coupling lightning and fire/smoke mapping products along with airmass back trajectories was developed to help determine the influence of biomass burning and lightning on individual rain events before applying to isotope source apportionment models. The annual IN wet deposition was 3.9 kg N·ha−1·yr−1, in which NH4+ and NO3− constituted 65% and 35%, respectively. Isotope mixing model results suggest vehicle emission contribution to NH3 can rival agriculture sources (i.e., fertilizer and livestock waste) in urban areas. Vehicles, biomass burning and lightning were significant NOx sources, while soil “biogenic” emissions increased substantially in certain rain events occurring in warmer months. This work qualified IN wet deposition flux and estimated IN emission source apportionments in a coastal small-sized city, which will inform regional N emission regulations and watershed restoration practices.

Stable sodium metal anode enabled by interfacial room‐temperature liquid metal engineering for high‐performance sodium–sulfur batteries with carbonate‐based electrolyte

AbstractSodium (Na) metal is a competitive anode for next‐generation energy storage applications in view of its low cost and high‐energy density. However, the uncontrolled side reactions, unstable solid electrolyte interphase (SEI) and dendrite growth at the electrode/electrolyte interfaces impede the practical application of Na metal as anode. Herein, a heterogeneous Na‐based alloys interfacial protective layer is constructed in situ on the surface of Na foil by self‐diffusion of liquid metal at room temperature, named “HAIP Na.” The interfacial Na‐based alloys layer with good electrolyte wettability and strong sodiophilicity, and assisted in the construction of NaF‐rich SEI. By means of direct visualization and theoretical simulation, we verify that the interfacial Na‐based alloys layer enabling uniform Na+ flux deposition and suppressing the dendrite growth. As a result, in the carbonate‐based electrolyte, the HAIP Na||HAIP Na symmetric cells exhibit a remarkably enhanced cycling life for more than 650 h with a capacity of 1 mAh cm−2 at a current density of 1 mA cm−2. When the HAIP Na anode is paired with sulfurized polyacrylonitrile (SPAN) cathode, the SPAN||HAIP Na full cells demonstrate excellent rate performance and cycling stability.