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Ammonia (NH3) has received considerable attention as a major reduced nitrogen. However, accurate estimates of the deposition amount are difficult due to its complex behavior characterized by bidirectional exchange between the atmosphere and the surface. We observed the vertical profile of NH3 concentration in a deciduous forest in Japan for 1 year to further advance the studies on NH3 bidirectional exchange in Asia, especially focusing on the process near the forest floor. The observation period lasted from September 29, 2020, to September 28, 2021, including leafy and leafless periods. Using the denuder sampling technique, we measured NH3 concentration in the forest at three heights (above the forest canopy, 30 m, and near the forest floor, 2 m and 0.2 m). NH3 concentrations tended to be highest at the top of the canopy (30 m). Focusing on the concentration near the forest floor, the concentrations at 0.2 m were frequently higher than those at 2 m regardless of the leafy and leafless period, thus suggesting NH3 emissions from the forest floor. NH3 concentration near the forest floor showed strong positive correlations with air temperature during the leafy period. The NH3 emissions from the forest floor during the leafy period were possibly due to the decomposition of leaf litter with increased air temperature. The decrease in leaf area index might induced the increase in NH3 concentration and emission. NH3 emission during the leafless period was also possibly dependent on the state of the deposition surface, apart from air temperature, relative humidity, and leaf area index. [ABSTRACT FROM AUTHOR]

Abstract Ammonia (NH3) has received considerable attention as a major reduced nitrogen. However, accurate estimates of the deposition amount are difficult due to its complex behavior characterized by bidirectional exchange between the atmosphere and the surface. We observed the vertical profile of NH3 concentration in a deciduous forest in Japan for 1 year to further advance the studies on NH3 bidirectional exchange in Asia, especially focusing on the process near the forest floor. The observation period lasted from September 29, 2020, to September 28, 2021, including leafy and leafless periods. Using the denuder sampling technique, we measured NH3 concentration in the forest at three heights (above the forest canopy, 30 m, and near the forest floor, 2 m and 0.2 m). NH3 concentrations tended to be highest at the top of the canopy (30 m). Focusing on the concentration near the forest floor, the concentrations at 0.2 m were frequently higher than those at 2 m regardless of the leafy and leafless period, thus suggesting NH3 emissions from the forest floor. NH3 concentration near the forest floor showed strong positive correlations with air temperature during the leafy period. The NH3 emissions from the forest floor during the leafy period were possibly due to the decomposition of leaf litter with increased air temperature. The decrease in leaf area index might induced the increase in NH3 concentration and emission. NH3 emission during the leafless period was also possibly dependent on the state of the deposition surface, apart from air temperature, relative humidity, and leaf area index. Graphical Abstract

[Display omitted] Intensive human activity has brought about unprecedented climate and environmental crises, in which concurrent heatwaves and ozone extremes pose the most serious threats. However, a limited understanding of the comprehensive mechanism hinders our ability to mitigate such compound events, especially in densely populated regions like China. Here, based on field observations and climate-chemistry coupled modelling, we elucidate the linkage between human activities and the climate system in heat-related ozone pollution. In China, we have observed that both the frequency and intensity of heatwaves have almost tripled since the beginning of this century. Moreover, these heatwaves are becoming more common in urban clusters with serious ozone pollution. Persistent heatwaves during the extremely hot and dry summers of 2013 and 2022 accelerated photochemical ozone production by boosting anthropogenic and biogenic emissions, and aggravated ozone accumulation by suppressing dry deposition due to water-stressed vegetation, leading to a more than 30% increase in ozone pollution in China's urban areas. The sensitivity of ozone to heat is demonstrated to be substantially modulated by anthropogenic emissions, and China's clean air policy may have altered the relationship between ozone and temperature. Climate model projections further highlight that the high-emission climate-socioeconomic scenario tends to intensify the concurrent heat and ozone extremes in the next century. Our results underscore that the implementation of a strict emission strategy will significantly reduce the co-occurrence of heatwaves and ozone extremes, achieving climate and environmental co-benefits. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a comprehensive solution aimed at enhancing our understanding of three-dimensional atmospheric pollutant dispersion. This innovative solution involves the development of a generalized model that extends previous research and is applicable to all parameterization schemes of these equations, including wind speed profiles and turbulent diffusion coefficients, while incorporating the dry deposition criterion. Our methodology involves subdividing the atmospheric boundary layer into distinct sub-layers, which facilitates a detailed examination of pollutant dispersion dynamics. Extensive validation with data from the Hanford experiment has demonstrated the accuracy of this solution in simulating pollutant concentrations. The results demonstrate that there is a strong correlation between the projected and observed concentrations, underscoring the statistical reliability of our approach. This validation situates the statistical indices of our solution within an acceptable range, confirming its accuracy in predicting atmospheric pollutant dispersion. These findings thus establish our solution as a valid and effective method for studying complex environmental phenomena. [ABSTRACT FROM AUTHOR]

Urbanization and industrialization have escalated air pollution into a critical global issue, particularly in urban areas. Urban green infrastructures (GIs), such as parks and street trees, play a vital role in mitigating air pollution through dry deposition, the process by which air pollutants are removed by deposition onto plant surfaces or through plant uptake. However, existing studies on the dry-deposition capacity of urban green spaces are limited in their ability to reflect variations at the tree-species level, hindering comprehensive evaluations and effective management strategies. This study aims to quantitatively assess the dry-deposition capacity of the urban green spaces of Beijing and Shanghai for six major air pollutants in using an improved dry-deposition model and tree-species-specific data. Results showed that Shanghai's urban green spaces had a monthly average dry-deposition rate of 5.5 × 10−6 s m−1, slightly higher than Beijing's rate of 5.3 × 10−6 s m−1. Significant seasonal variations were observed, with summer showing the highest deposition rates due to favorable meteorological conditions. Broad-leaved species such as Zelkova serrata in Beijing and Photinia serratifolia in Shanghai exhibited superior dry-deposition capacities compared to coniferous species. Temperature significantly influenced dry-deposition rates for gaseous pollutants, while particulate-matter deposition was primarily affected by pollutant concentrations. This study provides critical insights into the air = purification functions of urban green spaces and underscores the importance of species selection and strategic green-space planning in urban air-quality management, informing the development of optimized urban-greening strategies for improved air quality and public health. [ABSTRACT FROM AUTHOR]

Forest ecosystems depend on throughfall and stemflow fluxes for both water and nutrient input. Spatial and temporal variability of throughfall and stemflow fluxes are large and differ between tree species. The nutrient fluxes that accompany throughfall and stemflow are affected by climate, precipitation intensity, the seasonality of dry deposition, and canopy exchange processes. The interdependence of these factors makes it challenging to quantify changes in throughfall and stemflow amounts as well as their nutrient content. Here, we provide observation‐based evidence from 3.5 years of data collection with 222 rainfall events, of the seasonal variability of throughfall and stemflow magnitude and ion concentrations under a beech (Fagus silvatica) and spruce (Picea abies) tree. Interception and canopy cover were seasonally variable, average annual interception was 53% below beech, 61% below spruce and 68% below young spruce canopies. Further, we assess seasonality of ionic nutrients such as NH4 and NO3 as well as Mg, Ca and K and their dependence on both dry deposition and canopy exchange. Throughfall and stemflow were enriched compared to precipitation, with large differences between ions and different months. Antecedent precipitation was a main control on throughfall and stemflow enrichment. We developed a conceptual model of the potential drivers of throughfall and stemflow enrichment based on our observations. While NH4 and NO3 enrichment are likely dominated by dry deposition and dew and fog accumulation, Mg, Ca and K were additionally affected by canopy exchange. Observation based studies such as this one are needed to understand precipitation and nutrient partitioning across forests, which enables the prediction of how changes in climate and forest composition will affect local hydrology and nutrient inputs into forest ecosystems. [ABSTRACT FROM AUTHOR]

Combustion processes are the primary source of fine particulate matter in indoor air. Since the 1970s, plants have been extensively studied for their potential to reduce indoor air pollution. Leaves can retain particles on their surfaces, influenced by factors such as wax content and the presence of hairs. This study introduces an innovative experimental approach using metal oxide particles in an office-like environment to evaluate the depolluting effect of plant walls. Two plant walls were installed in a controlled room, housing three plant species: Aglaonema commutatum 'Silver Bay', Dracaena fragrans, and Epipremnum aureum. Metal oxide particles were introduced via a compressed air blower positioned between the two walls. The concentration of these particles was monitored using PM2.5 sensors, and the deposition of iron (Fe) on the leaves was quantified through Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This novel methodology effectively demonstrated the utility of both real-time sensors and ICP-MS in quantifying airborne particle concentrations and leaf deposition, respectively. The results revealed that Dracaena fragrans had a 44% higher Fe particle retention rate compared to the control (wallpaper). However, further validation through methodological replication is necessary to confirm the reproducibility of these findings. [ABSTRACT FROM AUTHOR]

In this study, the new data of experimental studies of the atmospheric particulate matter (PM) on the south-eastern coast of Lake Baikal (station Boyarsky) were analyzed in summer 2021. High-altitude measuring sites were arranged in the forest massif (mast, 16 m) and above the meadow vegetation (mast, 30 m). By the Giardina M. model and based on the measurements data the calculations of the deposition flux density of aerosol particles on forest and meadow vegetation were made. Our preliminary results of prediction obtained by Giardina M. model good agrees with measured dry deposition velocities across particle sizes. In the forest, the mass concentration of aerosol particles differs slightly from the mass concentrations in the grasslands and is equal on average 7.9 × 10−3 mg m−3 for the size particles below 200 nm (PM0.2) and 6.7 × 10−4 mg m−3 for particles in the size range from 0.2 to 10 μm (PM0.2–10). However, we found that mass flux density of aerosol particle is almost 4.8 times higher under forest canopy than in meadow vegetation. In addition, the leaf area index (LAI), which characterize the effective area of particle deposition, is also significantly higher in the tree canopy (5.6) compared to the grassland vegetation (2.4). [ABSTRACT FROM AUTHOR]

Trace metals from natural and anthropogenic sources impact the atmospheric environment and enter the soil through dry and wet atmospheric deposition, ultimately affecting human health. In this study, we established an emission inventory of Pb, As, Cr, and Cd in East Asia (80° E–140° E, 15° N–50° N) for the year 2017, including dust and anthropogenic sources from both land and marine. We modified the Community Multiscale Air Quality (CMAQ) model to provide gridded data on concentrations, as well as dry and wet atmospheric deposition fluxes of metals, with a focus on mainland China. The emissions of Pb, As, Cr, and Cd in East Asia were 19,253, 3415, 3332, and 9379 tons, respectively, in 2017, with 55%, 69%, 25%, and 58% distributed in the fine mode. The spatial distribution of atmospheric concentrations and dry deposition of trace metals was similar to that of emissions, while the spatial distribution of precipitation-related wet deposition was further east and greater in the south than in the north. In mainland China, the average bulk-deposition fluxes of Pb, As, Cr, and Cd were 1036.5, 170.3, 465.9, and 185.0 μg·m−2·year−1, respectively. Our study provides gridded data on trace metals in mainland China, which can be used for assessing air quality, human exposure risks, and metal inputs to soils. [ABSTRACT FROM AUTHOR]

Given factors such as reduced land availability for onshore wind farms, wind resource enrichment levels, and costs, there is a growing trend of establishing wind farms in deserts, the Gobi, and other arid regions. Therefore, the relationship between sand-dust weather environments and wind turbine operations has garnered significant attention. To investigate the impact of wind turbine wakes on sand-dust transportation, this study employs large eddy simulation to model flow fields, coupled with an actuator line model for simulating rotating blades and a multiphase particle in cell model for simulating sand particles. The research focuses on a horizontal axis wind turbine model and examines the motion and spatiotemporal distribution characteristics of four typical sizes of sand particles in the turbine wake. The findings reveal that sand particles of varying sizes exhibit a spiral settling pattern after traversing the rotating plane of wind turbine blades, influenced by blade shedding vortex and gravity. Sand particles tend to cluster in the peripheries of the vortex cores of low vorticity in the wind turbine wake. The rotation of wind turbines generates a wake vortex structure that causes a significant clustering of sand particles at the tip vortex. As the wake distance increases, the particles that cluster at the turbine's tip gradually spread outward to approximately twice the rotor diameter and then begin to mix with the incoming flow environment. Wind turbines have a noticeable impact on sand-dust transportation, hindering their movement to a significant extent. The average sand-blocking rate exhibits a trend of initially increasing and then decreasing as the wake distance increases. At its peak, the sand-blocking rate reaches an impressive 67.55%. The presence of wind turbines induces the advanced settling of sand particles, resulting in a "triangular" distribution of the deposition within the ground projection area of the wake. [ABSTRACT FROM AUTHOR]

Industrialization has led to severe environmental degradation, posing substantial health risks. The primary pollutants originate from land, air, and water sources. Monitoring air pollution typically requires expensive equipment. To address this, scientists have created various models based on specific criteria to predict air pollution levels. This paper explores an analytical solution to the problem of air pollution caused by point sources that disperse contaminants into the atmosphere. Specifically, it investigates how the removal processes affect the concentration of key pollutants. We apply the methods of separation of variables and Fourier transformation to derive an analytical solution for the mathematical model.

The size and composition of particulate matter (PM) are pivotal in determining its adverse health effects. It is important to understand PM's retention by plants to facilitate its atmospheric removal. However, the distinctions between the size and composition of naturally fallen PM (NFPM) and leaf-deposited PM (LDPM) are not well-documented. Here we utilize a single-particle aerosol mass spectrometer, coupled with a PM resuspension chamber, to analyze these differences. We find that LDPM particles are 6.8–97.3% larger than NFPM. Employing a neural network algorithm based on adaptive resonance theory, we have identified distinct compositional profiles: NFPM predominantly consists of organic carbon (OC; 31.2%) and potassium-rich components (19.1%), whereas LDPM are largely composed of crustal species (53.9–60.6%). Interestingly, coniferous species retain higher OC content (11.5–13.7%) compared to broad-leaved species (0.5–1.2%), while the levoglucosan content exhibit an opposite trend. Our study highlights the active role of tree leaves in modifying PM composition beyond mere passive capture, advocating for a strategic approach to species selection in urban greening initiatives to enhance PM mitigation. These insights provide guidance for urban planners and environmentalists in implementing nature-based solutions to improve urban air quality.

Robust estimates of historical changes in aerosols are key for accurate constraints on climate sensitivity. Dry deposition is a primary sink of aerosols from the atmosphere. However, most global climate models do not accurately represent observed strong dependencies of dry deposition following turbulent transport on aerosol size. It is unclear whether there is a substantial impact of mischaracterized aerosol deposition velocities on historical aerosol changes. Here we describe improved mechanistic representation of aerosol dry deposition in the NASA Goddard Institute for Space Studies (GISS) global climate model, ModelE, and illustrate the impact on 1850–2000 changes in global aerosol burdens as well as aerosol direct and cloud albedo effects using a set of 1850 and 2000 time slice simulations. We employ two aerosol configurations of ModelE (a "bulk" mass‐based configuration and a configuration that more explicitly represents aerosol size distributions, internal mixing, and microphysics) to explore how model structural differences in aerosol representation alter the response to representation of dry deposition. Both configurations show larger historical increases in the global burdens of non‐dust aerosols with the new dry deposition scheme, by 11% in the simpler mass‐based configuration and 23% in the more complex microphysical configuration. Historical radiative forcing responses, which vary in magnitude from 5% to 12% as well as sign, depend on the aerosol configuration. Plain Language Summary: Numerical models representing the Earth system are important tools for understanding the drivers of climate change and variability. Particles (also known as aerosols) in the atmosphere can influence climate by scattering or absorbing solar radiation and influencing clouds. How the amount of particles in the atmosphere has changed since preindustrial times is very uncertain. Many processes impact particle spatial distributions and changes with time, as well as how particles influence climate. Sources and sinks of particles need to be represented well in order to have confidence in estimates of changes in particles. Here we more accurately simulate dry deposition, which is a sink of particles, in a numerical model that represents the Earth system, and examine impacts on changes in the amount of particles in the atmosphere from preindustrial times to present day and the particles' influence on climate. Key Points: ModelE now has process‐based representation of aerosol dry deposition, and captures strong observed dependencies on particle sizeIncreases from 1850 to 2000 in the global non‐dust aerosol annual burdens are 11%–23% larger with more mechanistic dry depositionHistorical radiative forcing responses (−12% to +6%) depend on aerosol representation (e.g., microphysics and mixing state) [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agriculture generates ~83% of total US ammonia (NH3) emissions, potentially adversely impacting sensitive ecosystems through wet and dry deposition. Regions with intense livestock production, such as the dairy region of south-central Idaho, generate hotspots of NH3 emissions. Our objective was to measure the spatial and temporal variability of NH3 across this region and estimate its dry deposition. Ambient NH3 was measured using diffusive passive samplers at 8 sites in two transects across the region from 2018–2020. NH3 fluxes were estimated using the Surface Tiled Aerosol and Gaseous Exchange (STAGE) model. Peak NH3 concentrations were 4–5 times greater at a high-density dairy site compared to mixed agriculture/dairy or agricultural sites, and 26 times greater than non-agricultural sites with prominent seasonal trends driven by temperature. Annual estimated dry deposition rates in areas of intensive dairy production can approach 45 kg N ha−1 y−1, compared to <1 kg N ha−1 y−1 in natural landscapes. Our results suggest that the natural sagebrush steppe landscapes interspersed within and surrounding agricultural areas in southern Idaho receive NH3 dry deposition rates within and above the range of nitrogen critical loads for North American deserts. Finally, our results highlight a need for improved understanding of the role of soil processes in NH3 dry deposition to arid and sparsely vegetated natural ecosystems across the western US. [ABSTRACT FROM AUTHOR]

It is necessary to clear the relationship between physical and vegetation factors on the processes governing dissolved ion inputs to the forest floor to estimate correctly the values of atmospheric input to the forest. This study identified the factors influencing the differences in dissolved ion inputs to the forest floor between coniferous evergreen and broad-leaved deciduous species by analyzing the phenological variations of dry deposition and canopy exchange calculated by the canopy budget model under a high-deposition site near the city of Tokyo and a low-deposition site 84 km further away. At low-deposition site, vegetation factors such as capture efficiency did not explain the differences in Na+ or Cl− dry deposition. Leaf physiological characteristics influenced the differences in the Mg2+ and Ca2+ canopy leaching values, and phenology, leaf wettability, and diffusion processes from water film into leaves influenced the differences in NH4+ and NO3− input processes between tree types. At the high-deposition site, differences in the dry deposition of Na+, SO42−, Cl−, Mg2+, Ca2+, NH4+, and NO3− between tree types were influenced by differences in capture efficiency between coniferous and broad-leaved canopies in the leafed period and by the absence of leaves in deciduous species after leaf fall. These results indicated that atmospheric deposition affected the capture efficiency of coniferous trees for dry deposition and enhanced the difference of dissolved ion inputs to the forest floor between coniferous and deciduous species. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a comprehensive solution aimed at enhancing our understanding of three-dimensional atmospheric pollutant dispersion. This innovative solution involves the development of a generalized model that extends previous research and is applicable to all parameterization schemes of these equations, including wind speed profiles and turbulent diffusion coefficients, while incorporating the dry deposition criterion. Our methodology involves subdividing the atmospheric boundary layer into distinct sub-layers, which facilitates a detailed examination of pollutant dispersion dynamics. Extensive validation with data from the Hanford experiment has demonstrated the accuracy of this solution in simulating pollutant concentrations. The results demonstrate that there is a strong correlation between the projected and observed concentrations, underscoring the statistical reliability of our approach. This validation situates the statistical indices of our solution within an acceptable range, confirming its accuracy in predicting atmospheric pollutant dispersion. These findings thus establish our solution as a valid and effective method for studying complex environmental phenomena.

Abstract Robust estimates of historical changes in aerosols are key for accurate constraints on climate sensitivity. Dry deposition is a primary sink of aerosols from the atmosphere. However, most global climate models do not accurately represent observed strong dependencies of dry deposition following turbulent transport on aerosol size. It is unclear whether there is a substantial impact of mischaracterized aerosol deposition velocities on historical aerosol changes. Here we describe improved mechanistic representation of aerosol dry deposition in the NASA Goddard Institute for Space Studies (GISS) global climate model, ModelE, and illustrate the impact on 1850–2000 changes in global aerosol burdens as well as aerosol direct and cloud albedo effects using a set of 1850 and 2000 time slice simulations. We employ two aerosol configurations of ModelE (a “bulk” mass‐based configuration and a configuration that more explicitly represents aerosol size distributions, internal mixing, and microphysics) to explore how model structural differences in aerosol representation alter the response to representation of dry deposition. Both configurations show larger historical increases in the global burdens of non‐dust aerosols with the new dry deposition scheme, by 11% in the simpler mass‐based configuration and 23% in the more complex microphysical configuration. Historical radiative forcing responses, which vary in magnitude from 5% to 12% as well as sign, depend on the aerosol configuration.

Particulate matter (PM) is a critical air pollutant, responsible for an array of ailments leading to premature mortality worldwide. Nature-based solutions for mitigation of PM and especially role of forests in mitigating PM from an ecosystem perspective are less explored. Forests provide a natural pollution abatement strategy by providing a surface area for the deposition of PM. Depending on their structure and composition, forests have varying capacities for PM adsorption, which is again less explored. Hence, in the present study, we evaluate the removal capacity of PM by the forest-type groups of India. Deposition flux and total PM removal across sixteen forest types were estimated based on the 2019 dataset of PM using Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) data. Externality values and PM removal costs by industrial equipment were used for associating an economic value to the air pollution abatement service by forests. The total PM2.5 removal by forests in 2019 was estimated to be 1361.28 tons and PM10 was estimated to be 303,658.27 tons. Deposition of PM was found to be high in littoral and swamp forests, tropical semi-evergreen forests, tropical moist deciduous forests, and sub-tropical pine forests. Tropical dry deciduous forests had the highest net weight % removal of PM with 39% removal for PM2.5 and 39% removal for PM10. The air pollution abatement service by forests for PM removal was 188 M US dollars (USD) with externality-based removal service by forests of 2009 M USD. The net PM removed by all forests of India was estimated to be approximately worth ₹ 470–648 Crore (59–81 million dollars) for PM2.5 and worth ₹56,746–1,22,617 Crore (7093–15,327 million dollars) for PM10 based on valuation using value transfer method. The study concludes that forests can be a significant contributor to PM reduction at a global level. Especially for India’s National Clean Air Programme and further research and policy considerations, the findings would be extremely useful. [ABSTRACT FROM AUTHOR]

In this study, the new data of experimental studies of the atmospheric particulate matter (PM) on the south-eastern coast of Lake Baikal (station Boyarsky) were analyzed in summer 2021. High-altitude measuring sites were arranged in the forest massif (mast, 16 m) and above the meadow vegetation (mast, 30 m). By the Giardina M. model and based on the measurements data the calculations of the deposition flux density of aerosol particles on forest and meadow vegetation were made. Our preliminary results of prediction obtained by Giardina M. model good agrees with measured dry deposition velocities across particle sizes. In the forest, the mass concentration of aerosol particles differs slightly from the mass concentrations in the grasslands and is equal on average 7.9 × 10−3 mg m−3 for the size particles below 200 nm (PM0.2) and 6.7 × 10−4 mg m−3 for particles in the size range from 0.2 to 10 μm (PM0.2–10). However, we found that mass flux density of aerosol particle is almost 4.8 times higher under forest canopy than in meadow vegetation. In addition, the leaf area index (LAI), which characterize the effective area of particle deposition, is also significantly higher in the tree canopy (5.6) compared to the grassland vegetation (2.4).

Combustion processes are the primary source of fine particulate matter in indoor air. Since the 1970s, plants have been extensively studied for their potential to reduce indoor air pollution. Leaves can retain particles on their surfaces, influenced by factors such as wax content and the presence of hairs. This study introduces an innovative experimental approach using metal oxide particles in an office-like environment to evaluate the depolluting effect of plant walls. Two plant walls were installed in a controlled room, housing three plant species: Aglaonema commutatum ‘Silver Bay’, Dracaena fragrans, and Epipremnum aureum. Metal oxide particles were introduced via a compressed air blower positioned between the two walls. The concentration of these particles was monitored using PM2.5 sensors, and the deposition of iron (Fe) on the leaves was quantified through Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This novel methodology effectively demonstrated the utility of both real-time sensors and ICP-MS in quantifying airborne particle concentrations and leaf deposition, respectively. The results revealed that Dracaena fragrans had a 44% higher Fe particle retention rate compared to the control (wallpaper). However, further validation through methodological replication is necessary to confirm the reproducibility of these findings.

Narragansett Bay, the largest estuary in New England, is a heavily urbanized watershed impacted by deposition and runoff. Nutrient budgets and local policy rely on deposition data from a 1990 study that did not include any direct observations of dry deposition of gaseous ammonia (NH3(g)) and particulate ammonium (p‐NH4+) due to uncertainties in their flux direction and measurement difficulty. Recent work has shown that wet deposition of ammonium (NH4+) to the Bay has increased by a factor of 6 over the past three decades, leading to a 2.5‐fold increase in wet nitrogen (N) deposition. This documented increase in wet deposition of NH4+ is concurrent with managed nutrient reductions in urbanized estuaries but has potentially increased the impacts of atmospheric N deposition, including the dry deposition of NH3(g) and p‐NH4+. However, the lack of NH3(g) and p‐NH4+ measurements hinders our interpretation of this important N source. For the first time over Narragansett Bay, and to our knowledge over open water, dry (particulate and gas phase) total ammonia (NHx = NH3(g) + p‐NH4+) and the bidirectional NH3(g) flux were quantified using a relaxed eddy accumulation sampling technique. We find that dry deposition of NHx comprises 9.6% of total (wet + dry) N deposition. During the fall season, the dominant flux direction for NH3(g) is upward, which also has implications for urban air quality. We estimate that NH3(g) emitted from the Bay to the atmosphere makes up to 10% of the local NH3(g) emission budget for fall. Plain Language Summary: Estuaries around the world receive nitrogen from various sources, including from the atmosphere through rainfall (wet deposition) and gasses and particulates (dry deposition). Such is the case in Narragansett Bay, RI, where a scarcity of measurements hinders our understanding of how atmospheric nitrogen influences this system. Recent work has shown that wet deposition has increased by 2.5‐fold since 1990, driven by a 6‐fold increase in ammonium wet deposition. Gaseous ammonia is subjected to few emission regulations and is poorly understood because gaseous ammonia can flux upward and downward (bi‐directional). For the first time over Narragansett Bay, and to our knowledge over open water, dry deposition of total ammonia (gaseous ammonia + particulate ammonium) and the gaseous ammonia flux were quantified using a technique called relaxed eddy accumulation. We found that dry deposition of total ammonia made up 9.6% of total nitrogen deposition. The dominant flux direction of gaseous ammonia was upward (i.e., out of the water) during the fall season. Loss of nitrogen from the Bay to the atmosphere has implications for urban air quality. We estimated that gaseous ammonia emitted from the Bay to the atmosphere makes up to 10% of the local gaseous ammonia emission budget. Key Points: Dry deposition of gaseous ammonia and particulate ammonium comprises 9.6% of total nitrogen entering Narragansett Bay from the atmosphereThe dominant flux of gaseous ammonia is upward (out of the water) during the fall season when surface water concentrations are elevatedAmmonia released from Narragansett Bay to the atmosphere makes up to 10% of the local gaseous ammonia emission budget [ABSTRACT FROM AUTHOR]

Atmospheric dry deposition of black carbon (BC) is a significant but poorly understood and inadequately described process in aerosol-climate models. The 40-year detailed dry deposition velocities of hydrophilic BC over China from 1981 to 2020 were systematically studied based on the MERRA-2 reanalysis data, which hopefully will be beneficial for its applications in atmospheric systems for climate and air quality. The average dry deposition flux of hydrophilic BC over China was 0.00059 ± 0.00014 μg m−2 s−1, while its dry deposition velocity was estimated to be 0.00051 ± 0.00004 m s−1. The monthly mean dry deposition fluxes of hydrophilic BC varied nearly 1.5 fold, ranging from the lowest 0.00046 ± 0.00011 μg m−2 s−1 in August to the highest 0.00068 ± 0.00019 μg m−2 s−1 in January. The spring season had the highest mean dry deposition flux of hydrophilic BC, followed by summer and winter, whereas autumn showed relatively weaker dry deposition flux. The mean dry deposition velocities of hydrophilic BC over the Beijing-Tianjin-Hebei region, Yangtze River Delta, Pearl River Delta and Tibet Plateau were estimated to be 0.00042 ± 0.00004, 0.00042 ± 0.00004, 0.00051 ± 0.00006 and 0.00078 ± 0.00005 m s−1, respectively. The monthly and seasonal patterns of dry deposition velocities of hydrophilic BC differed from each other in different regions, and high air temperature or surface wind speed seemed to fortify dry deposition velocities of hydrophilic BC. Our study pointed to high dry deposition flux of hydrophilic BC in the northern China Plain and Sichuan Basin but large dry deposition velocities in the Tibet Plateau region. [ABSTRACT FROM AUTHOR]

Dry deposition of ozone is an important sink of ozone in near surface air. When dry deposition occurs through plant stomata, ozone can injure the plant, altering water and carbon cycling and reducing crop yields. Quantifying both stomatal and nonstomatal uptake accurately is relevant for understanding ozone's impact on human health as an air pollutant and on climate as a potent short-lived greenhouse gas and primary control on the removal of several reactive greenhouse gases and air pollutants. Robust ozone dry deposition estimates require knowledge of the relative importance of individual deposition pathways, but spatiotemporal variability in nonstomatal deposition is poorly understood. Here we integrate understanding of ozone deposition processes by synthesizing research from fields such as atmospheric chemistry, ecology, and meteorology. We critically review methods for measurements and modeling, highlighting the empiricism that underpins modeling and thus the interpretation of observations. Our unprecedented synthesis of knowledge on deposition pathways, particularly soil and leaf cuticles, reveals process understanding not yet included in widely-used models. If coordinated with short-term field intensives, laboratory studies, and mechanistic modeling, measurements from a few long-term sites would bridge the molecular to ecosystem scales necessary to establish the relative importance of individual deposition pathways and the extent to which they vary in space and time. Our recommended approaches seek to close knowledge gaps that currently limit quantifying the impact of ozone dry deposition on air quality, ecosystems, and climate.

The dry deposition flux of particles smaller than 2.5 µm was investigated considering agricultural and urban regions. The concentrations, size distributions, and chemical characterization of particulate matter (PM) were evaluated and related to emission sources. The concentrations of fine PM were associated to the highest number of wildfire outbreaks. The results of the PM samples combined with the analyses of the air mass trajectories evidenced that the transport of this pollutant may have come from regions with industries that use biomass as fuel. The predominant water‐soluble ions in coarse and fine particulate were nitrate, potassium, calcium, magnesium, potassium, sulfate, and nitrate, respectively. The deposition fluxes of potassium, nitrate, and sulfate ions were higher during the sugarcane harvest than during the off‐season. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Computational Mechanics / Jisuan Lixue Xuebao is the property of Chinese Journal of Computational Mechanics Editorial Office, Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Atmospheric deposition is an important source for the P biological cycle, especially for P‐limited ecosystems. In the present study, 48 hr size‐segregated aerosol samples were collected at an urban site in Shanghai for one year from May 2019 to June 2020. Total phosphorus (TP) presented a bimodal distribution in four seasons, which was mainly contributed by mineral dust in the coarse mode, and was related to anthropogenic and combustion emissions in the fine mode. Dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP) presented a bimodal distribution in spring and summer, and a unimodal distribution dominated by a fine mode in autumn and winter. Size distributions and correlation analysis showed that DIP in the fine and coarse modes originated from the acid processing of SO42‐ and NO3−, respectively, while DOP was mainly from biomass burning emissions. Positive Matrix Factor analysis showed that phosphorus (P) in atmospheric aerosols in Shanghai was mainly contributed by four sources, including crustal sources, sea‐salt, industry emissions and fossil fuel combustion, and biomass burning. Industry emissions and fossil fuel combustion, as well as biomass burning were important sources of TP in all particle sizes (50%–65%). Biomass burning was the most important source of DOP (>50%). The total deposition flux of total dissolved phosphorus (TDP) calculated based on the size‐weighted deposition velocity model averaged 75.2 ± 17.4 μg/m2/d. Assuming that all of TDP is bioavailable, TDP deposition can create a primary production of 8.0 mg C/m2/d, which can support 1.3%–4.4% of the new production in the East China Sea. Plain Language Summary: Phosphorus (P) has become one of the main factors limiting the primary productivity in many ecosystems. Currently, limited measurements of P especially soluble P leads to a large discrepancy between observations and model results and substantial uncertainties in quantifying the effect of atmospheric P deposition. Therefore, comprehensive knowledge regarding its sources, chemical compositions, atmospheric formation and evolution, and size distribution is required. Based on the collected samples, we first characterized the concentrations, size distributions, seasonal variations, sources, and dry deposition fluxes of different P forms in Shanghai. We also investigated the effects of sources and atmospheric acidic processing on the size distribution of. Based on these results. Our results showed total phosphorus presented a bimodal distribution, which was mainly contributed by mineral dust in the coarse mode and was related to anthropogenic and combustion emissions in the fine mode. Dissolved inorganic phosphorus and dissolved organic phosphorus presented a bimodal distribution in spring and summer, and a unimodal distribution dominated by a fine mode in autumn and winter. We estimated that total dissolved phosphorus flux can support 1.3%–4.4% of the new production in the East China Sea, emphasizing the important role of atmospheric P deposition to the marine ecosystem. Key Points: Total phosphorus showed a bimodal distribution, with one peak occurring in each of the coarse and fine modesDissolved inorganic phosphorus showed a unimodal distribution, while dissolved organic phosphorus showed a distinct bimodal distributionThe size distributions of different phosphorus forms were related to the sources and atmospheric acidic processing [ABSTRACT FROM AUTHOR]

PM2.5-bound trace elements were chosen for health risk assessment because they have been linked to an increased risk of respiratory and cardiovascular illness. Since the Korean national air quality standard for ambient particulate matter is based on PM2.5 mass concentration, there have only been a few measurements of PM2.5 particles together with trace elements that can be utilized to evaluate their effects on air quality and human health. Thus, this study describes the trace elements bound to PM2.5 in Seoul (urban area) and Seosan (rural area) using online nondestructive energy-dispersive X-ray fluorescence analysis from December 2020 to January 2021. At both the Seoul and Seosan sites, S, K, Si, Ca, and Fe constituted most of the PM2.5-bound trace elements (~95%); major components such as S, K, and soil (estimatedcalculatedcalculated based on oxides of Si, Fe, Ca, and Ti) were presumably from anthropogenic and crustal sources, as well as favorable meteorological conditions. During winter, synoptic meteorology favored the transport of particles from severely contaminated regions, such as the East Asian outflow and local emissions. The total dry deposition flux for crustal elements was 894.5 ± 320.8 µg m−2 d−1 in Seoul and 1088.8 ± 302.4 µg m−2 d−1 in Seosan. Moreover, potential health risks from the trace elements were estimated. Cancer risk values for carcinogenic trace elements (Cr, As, Ni, and Pb) were within the tolerable limit (1 × 10−6), suggesting that adults and children were not at risk of cancer throughout the study period in Seoul and Seosan. Furthermore, a potential risk assessment of human exposure to remaining carcinogens (Cr, As, Ni, and Pb) and non-carcinogens (Cu, Fe, Zn, V, Mn, and Se) indicated that these trace elements posed no health risks. Nevertheless, trace element monitoring, risk assessment, and mitigation must be strengthened throughout the study area to confirm that trace-element-related health effects remain harmless. Researchers and policymakers can use the database from this study on spatial and temporal variation to establish actions and plans in the future. [ABSTRACT FROM AUTHOR]

Trace metals from natural and anthropogenic sources impact the atmospheric environment and enter the soil through dry and wet atmospheric deposition, ultimately affecting human health. In this study, we established an emission inventory of Pb, As, Cr, and Cd in East Asia (80° E–140° E, 15° N–50° N) for the year 2017, including dust and anthropogenic sources from both land and marine. We modified the Community Multiscale Air Quality (CMAQ) model to provide gridded data on concentrations, as well as dry and wet atmospheric deposition fluxes of metals, with a focus on mainland China. The emissions of Pb, As, Cr, and Cd in East Asia were 19,253, 3415, 3332, and 9379 tons, respectively, in 2017, with 55%, 69%, 25%, and 58% distributed in the fine mode. The spatial distribution of atmospheric concentrations and dry deposition of trace metals was similar to that of emissions, while the spatial distribution of precipitation-related wet deposition was further east and greater in the south than in the north. In mainland China, the average bulk-deposition fluxes of Pb, As, Cr, and Cd were 1036.5, 170.3, 465.9, and 185.0 μg·m−2·year−1, respectively. Our study provides gridded data on trace metals in mainland China, which can be used for assessing air quality, human exposure risks, and metal inputs to soils.

The dry deposition of ozone from the atmosphere to ecosystems is an important coupling mechanism between atmospheric chemistry and terrestrial biogeochemical processes. In most Earth system models, dry deposition is simulated using a resistor‐in‐series approach that aims to parameterize the governing biological, chemical, and physical processes through a series of functional approximations. Here, we evaluate the influence of carbon cycle‐climate responses on this parameterization using the results of the Energy Exascale Earth System Model v1.1 Biogeochemistry simulation campaign. This simulation campaign was designed in part to explore the biophysical and radiative effects of rising historical CO2 concentrations on the Earth system. We find that while the global annual ozone dry deposition is relatively insensitive to these effects, regionally the influence can be up to 10%. The strongest regional sensitivities in ozone dry deposition are predominantly in higher latitudes over land in the northern hemisphere and are dominated by the radiative effect of CO2, with little net influence of biophysical responses. Of all the impacts of the radiative effect of CO2, we point to the potential importance of accurately representing ozone deposition to snow in Earth System Models and provide recommendations for future simulation campaigns. Plain Language Summary: Ozone is removed from the atmosphere through a process known as "dry deposition." Most climate and air quality models use a similar method to predict ozone dry deposition. Here, we evaluate the impact of rising CO2 concentrations on ozone dry deposition using this widely used prediction method and a global climate model. We find that the global total amount of ozone deposition doesn't change much with rising CO2 concentrations. However, regionally the changes can be large. Using a set of computer simulation experiments we find that most of these changes are driven by the interactions of rising CO2 with radiation, as opposed to the interactions of CO2 with plants. Key Points: We evaluate the influence of historical carbon cycle‐climate responses on simulated ozone dry depositionThe net effect of carbon‐cycle climate responses on ozone deposition is small on the global average, but regionally can be up to 10%The radiative effect of CO2 dominates the sensitivity of ozone dry deposition to rising CO2 concentrations [ABSTRACT FROM AUTHOR]

This study collected ambient air total suspended particle (TSP) concentrations and dry depositions at Taichung Science Park sampling site. The metallic elements concentrations and dry depositions were analyzed. The possible pollutant sources are discussed in this study. In addition, this study used the principal component analysis method to find metallic element sources and their transportation pathway and distributions at Taichung Science Park (T.S.P). The results indicated that the average highest TSP concentrations and dry deposition fluxes occurred in the autumn and winter seasons. The highest average metallic element concentration and dry deposition was Fe, while the lowest average metallic element concentration and dry deposition was Hg(p). The study results further indicated that the lowest metallic element concentrations and dry depositions all occurred in the summer season. The pollutant parcels originated from the northern Taiwan counties and sea surface in the autumn, winter and spring seasons. Factor 1 was responsible for the local industrial emission results and traffic road dust. The metallic elements Hg(p) yield a value greater than 0.7 in Factor 2 which revealed that ambient air particulate pollutants were generated from Taichung Thermal Power Plant (T.T.P.P.) emissions and were transported from the coastal area of mainland China cities. The mean seasonal concentration differences existed for ambient air particulates, and there were no mean seasonal concentrations differences for all metallic elements. In addition, there were no significant mean concentrations differences for all metallic elements and meteorological factors such as temperature, humidity and wind speed. Therefore, the ambient air metallic element emissions were stable and considered primary emissions sources. The health risk value for metallic element Cr was higher than that for the acceptable health risk value suggested by the EPA. Metallic element Cr revealed that it was no mean seasonal concentrations differences. Thus, metallic element Cr was considered came from local emission source at this T.S.P. sampling site. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agriculture generates ~83% of total US ammonia (NH3) emissions, potentially adversely impacting sensitive ecosystems through wet and dry deposition. Regions with intense livestock production, such as the dairy region of south-central Idaho, generate hotspots of NH3 emissions. Our objective was to measure the spatial and temporal variability of NH3 across this region and estimate its dry deposition. Ambient NH3 was measured using diffusive passive samplers at 8 sites in two transects across the region from 2018–2020. NH3 fluxes were estimated using the Surface Tiled Aerosol and Gaseous Exchange (STAGE) model. Peak NH3 concentrations were 4–5 times greater at a high-density dairy site compared to mixed agriculture/dairy or agricultural sites, and 26 times greater than non-agricultural sites with prominent seasonal trends driven by temperature. Annual estimated dry deposition rates in areas of intensive dairy production can approach 45 kg N ha−1 y−1, compared to −1 y−1 in natural landscapes. Our results suggest that the natural sagebrush steppe landscapes interspersed within and surrounding agricultural areas in southern Idaho receive NH3 dry deposition rates within and above the range of nitrogen critical loads for North American deserts. Finally, our results highlight a need for improved understanding of the role of soil processes in NH3 dry deposition to arid and sparsely vegetated natural ecosystems across the western US.

• A data set of 10Be in surface snow from coastal to inland Antarctica is presented. • A boundary of the deposition regime was found at around 75°S at 3.5 km elevation. • Transport from the stratosphere might also affect the spatial distribution of 10Be. To contribute further to understanding of the nature of 10Be deposition in Antarctica, we determined 10Be concentrations in surface snow samples obtained along the inland traverse route of the 59th and 60th Japanese Antarctic Research Expeditions (JAREs) in eastern Dronning Maud Land. The 10Be concentrations ranged between 3.7 × 103 and 8.6 × 104 atoms/g. When plotted against latitude, they showed a clear trend of increasing concentration southward with an upward inflection point at around 75°S (elevation 3.5 km) for the 59th JARE. Comparison with both snow accumulation rate and δ18O data suggests that the inflection point divides the dominant deposition regime into two different groups: wet deposition (north of 75°S) and dry deposition with slight enhancement of 10Be fallout further inland (south of 75°S). Additional factors associated with 10Be transport from the stratosphere are also proposed. [ABSTRACT FROM AUTHOR]

Dry deposition of aerosols from the atmosphere is an important but poorly understood and inadequately modeled process in atmospheric systems for climate and air quality. Comparisons of currently used aerosol dry deposition models to a compendia of published field measurement studies in various landscapes show very poor agreement over a wide range of particle sizes. In this study, we develop and test a new aerosol dry deposition model that is a modification of the current model in the Community Multiscale Air Quality (CMAQ) model. The new model agrees much better with measured dry deposition velocities across particle sizes. The key innovation is the addition of a second inertial impaction term for microscale obstacles such as leaf hairs, microscale ridges, and needleleaf edge effects. The most significant effect of the new model is to increase the mass dry deposition of the accumulation mode aerosols in CMAQ. Accumulation mode mass dry deposition velocities increase by almost an order of magnitude in forested areas with lesser increases for shorter vegetation. Peak PM2.5 concentrations are reduced in some forested areas by up to 40% in CMAQ simulations. Over the continuous United States, the new model reduced PM2.5 by an average of 16% for July 2018 at the Air Quality System monitoring sites. For summer 2018 simulations, bias and error of PM2.5 concentrations are significantly reduced, especially in forested areas. Plain Language Summary: Aerosol dry deposition is an important sink for atmospheric particles that are a health hazard and a significant climate forcer. Uncertainties in modeling aerosol dry deposition hamper accurate predictions of air quality and climate. A new aerosol dry deposition model is developed that better agrees with observations of aerosol dry deposition velocity for a variety of vegetation such as forests, grasslands, and water surfaces. This improved aerosol dry deposition model when incorporated into air quality and climate models will improve the accuracy of model predictions. Key Points: New aerosol deposition velocity model agrees better with observations than current modelsImpaction on microscale obstacles such as leaf hairs is key processNew aerosol deposition velocity model increases dry deposition of PM2.5 compared to the current Community Multiscale Air Quality model [ABSTRACT FROM AUTHOR]

Ambient air pollutants have detrimental effects on human health and ambient air quality in central Taiwan is worsening. The aims of this study are as follows: (1) Measure the ambient air concentrations and dry deposition fluxes of particulates at a mixed commercial, urban and traffic sampling site in Luliao. (2) Identify the metallic elements that are attached to the particulates at this mixed sampling site. (3) Discuss the effects of ambient air pollutants (metallic elements that are attached to the particulates) on the health of local people using contamination factors and degrees of contamination [Ghosh et al. (2018). Source and chemical species characterization of PM10 and human health risk assessment of semi-urban, urban and industrial areas of West Bengal, India. Chemosphere 207:626–636]. The mean total suspended particulate concentrations were highest in the winter and lowest in the summer. The deposition fluxes were highest in the autumn and lowest in the summer. ANOVA results revealed no significant seasonal variation in the concentrations or dry depositions of particulates and metallic elements (Al, Cd, Cr, Mn, Ni, Pb and Zn) at the sampling site. Cu was the only exception, as its concentration varied seasonally. Degrees of contamination and contamination factor values for metallic elements Cd, Cr, Cu, Mn, Ni, Pb and Zn were low. Most of the metallic elements – Zn, Cr, Ni, Cd, Pb and Al – were locally emitted. Local residents close to the site faced no immediate carcinogenic or other health-related risk. Taichung World Flora Exposition was held in Taichung city and lasted as long as six months, and traffic flow increased significantly during this period. Hence, high density traffic flow during the Taichung World Flora Exposition might have been responsible for the high concentration and seasonal variations concentrations of metallic elements Cu and Mn at this time. [ABSTRACT FROM AUTHOR]

Exchanges of reactive gases between forests and the atmosphere influence tropospheric chemistry, climate, and ecosystems. Chemistry inside canopies can alter these exchanges yet understanding of the chemistry and processes influencing the chemistry is incomplete. Previous work prioritizes complex chemical mechanisms over micrometeorology in the multilayer models of forests used to understand in‐canopy chemistry and its impacts. Instead, here we use a new simplified chemical mechanism and resolve turbulence in a multilayer canopy model. Specifically, we describe a new version of the National Center for Atmospheric Research large eddy simulation (LES) coupled to both a multilayer canopy model and a chemical mechanism. The mechanism has 41 reactions and 19 gases for ozone, NOx (=NO + NO2), HOx (=OH + HO2), and isoprene chemistry. We evaluate the mechanism against two more complex mechanisms using box modeling. We configure the LES for a temperate deciduous forest and summer midday weak‐wind buoyancy‐forced conditions. The multilayer canopy model necessitates estimates of reactant sources and sinks at each canopy level, and thus we describe multilayer parameterizations for dry deposition and biogenic emissions. For the first time with an LES coupled to both a multilayer canopy and chemistry, we demonstrate variability in chemical reactions due to turbulence‐induced segregation of reactants inside and just above the canopy. For the cases examined here, in‐canopy segregation alters reaction rates that only consider well‐mixed conditions by up to −48% to +23%. For many reactions, segregation is stronger when soil NO emissions reflect the upper bound of observed values for temperate forests. Plain Language Summary: The atmospheric boundary layer (ABL) (the part of the atmosphere closest to the earth) organizes itself into structured air motions that vertically transport momentum, energy, and reactive gases toward and away from the Earth's surface. This is important because the Earth's surface provides sources and sinks of momentum, energy, and reactive gases. The presence of forest canopies can alter the structured air motions in the ABL, and the structured air motions influence canopy sources and sinks of momentum, energy, and reactive gases, implying a coupling between the canopy and the structured air motions that may influence atmospheric chemistry. We describe a computer model with very high spatial resolution that can be used to examine the impact of the relationship between these organized motions, the canopy, and chemistry. Other computer models that have been used to examine atmospheric chemistry in canopies only consider the average effect of the organized motions. We show that the organized motions can influence chemical reaction rates substantially in the canopy, rendering the model described here an important tool for interpreting observations and advancing understanding of the impact on atmospheric chemistry important for climate and air pollution. Key Points: We describe a new tool for investigating canopy‐chemistry‐turbulence interactions at isoprene‐dominated deciduous forestsSpatial segregation of air masses in the canopy can bias reaction rates assuming well‐mixed conditions by up to −48% to +23%There is stronger segregation for many reactions when soil NO emissions reflect the upper bound of observed values for temperate forests [ABSTRACT FROM AUTHOR]

Dry deposition is an important ozone sink that impacts ecosystem carbon and water cycling. Ozone dry deposition in forests is regulated by vertical transport, stomatal uptake, and non‐stomatal processes including chemical removal. However, accurate descriptions of these processes in deposition parameterizations are hindered by sparse observational constraints on individual sink terms. Here we quantify the contribution of canopy‐atmosphere turbulent exchange and chemical ozone removal by soil‐emitted nitric oxide (NO) to ozone deposition in a North‐Italian broadleaf deciduous forest. We apply a multi‐layer canopy exchange model to interpret campaign observations of nitrogen oxides (NOx = NO + NO2) and ozone exchange above and inside the forest canopy. Two state‐of‐science parameterizations of in‐canopy vertical diffusivity, based on above‐canopy wind speed or stability, do not reproduce the observed exchange suppressed by canopy‐top radiative heating, resulting in overestimated dry deposition velocities of 10%–19% during daytime. Applying observation‐derived vertical diffusivities in our simulations largely resolves this overestimation. Soil emissions are an important NOx source despite the observed high background NOx levels. Soil NOx emissions decrease the gradient between canopy and surface layer NOx mixing ratios, which suppresses simulated NOx deposition by 80% compared to a sensitivity simulation without soil emissions. However, a sensitivity analysis shows that the enhanced chemical ozone sink by reaction with soil‐emitted NO is offset by increased vertical ozone transport from aloft and suppressed dry deposition. Our results highlight the need for targeted observations of non‐stomatal ozone removal and turbulence‐resolving deposition simulations to improve quantification and model representation of forest ozone deposition. Plain Language Summary: Ozone is a harmful air pollutant that impacts human and ecosystem health. Ozone can be removed by forest ecosystems as a result of air transport into forests followed by plant ozone uptake or chemical removal, but quantifying these individual processes is difficult. We combine model simulations and treetop measurements to study the role of vertical forest‐atmosphere air transport and chemical ozone removal inside the forest. We find that our model can only reproduce surface ozone removal if we account for suppressed transport as derived from observations. The soil is a substantial source of nitric oxide (NO) that reacts with ozone. According to our analysis, the presence of a soil NO source does not lead to increased ozone removal because other ozone sinks are reduced. Our results suggest that individual ozone removal processes in forests can best be studied using targeted observations and models that better resolve forest‐atmosphere exchange. Key Points: We use a multi‐layer canopy‐atmosphere exchange model to interpret ozone flux observations inside and above a North‐Italian forestTwo state‐of‐science vertical exchange parameterizations do not capture in‐canopy stable stratification suppressing ozone depositionSoil nitric oxide emissions do not increase ozone deposition due to compensating effects by deposition and transport [ABSTRACT FROM AUTHOR]

Airborne pesticide drift poses a substantial environmental threat in agriculture, affecting ecosystems far from the application sites. This process, in which up to 25% of applied pesticides are carried by air currents, can transport chemicals over hundreds or even thousands of kilometers. Drift rates peak during the summer months, reaching as high as 60%, and are influenced by various factors, including wind speed, temperature, humidity, and soil type. Pesticide volatilization is a significant concern, occurring 25 times more frequently than surface runoff. Under certain conditions, it can result in chemical losses of compounds like metolachlor and atrazine that are up to 150 times higher. These drifting pesticides have profound impacts on biodiversity, harming non-target plants, insects, fungi, and other organisms both near application sites and in distant ecosystems. Pesticide drift has been linked to over 50% reductions in wild plant diversity within 500 m of fields, reducing floral resources for pollinators. Despite growing evidence of these effects, the long-term consequences of airborne pesticides on biodiversity remain poorly understood, especially in complex field conditions with multiple pesticide applications. Addressing this requires urgent measures, such as improved meteorological tracking during applications, adoption of biopesticides, and integrated pest management strategies. This review highlights the pressing need for research to quantify airborne pesticides' ecological impacts, advocating for sustainable practices to mitigate environmental damage., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Saeed Albaseer reports financial support was provided by Alexander von Humboldt Foundation. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Dew formation takes place when atmospheric water vapor condenses on the surface which cools down due to radiation deficit. As it is a local phenomenon, its study gives information about the pollutants present in the atmosphere. Also, since dew formation is a natural phenomenon, and involves passive cooling, this can be a potential method for atmospheric water harvesting. The main intention of this present research work was the collection of dew samples and their analysis for yield and chemical composition. Dew samples were collected on a self-fabricated dew collection set up during the winter season. In total 30 dew samples were collected and analyzed for ionic constituents. The results were then compared to those of rain samples. The pH of dew was found to be in the range of 7-8.7, showing the neutral to alkaline nature of dew. Ionic compositions were higher in dew than in rain. While sulfate largely contributed to the ion composition of dew, nitrate was the least contributing ion. The average concentration for sulfate and nitrate in dew were found to be 0.55 and 0.03 meq/L, respectively. The average yield of dew was found to be 0.13L/m 2 . This yield value from the simplest of collection set-up ensures that dew can be considered as the potential water source with advanced condensing material and passive/active cooling in arid and semi-arid regions.