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Atmospheric correction plays an important role in satellite monitoring of lake water quality. However, different atmospheric correction algorithms yield significantly different accuracy for inland lake waters beset by shallowness and turbidity. Finding a suitable algorithm for a specific lake is critical for quantitative satellite water-environmental monitoring. This study used Landsat 8 and Sentinel 2 L1 level data of Ebinur Lake in arid northwest China on May 19, 2021. Atmospheric corrections were performed using FLAASH, QUAC, 6S, Acolite-DSF and Acolite-EXP algorithms. The Sentinel 2 reflectance product verified the consistency of the algorithms. Quasi-simultaneously measured hyperspectral data determined the algorithm applicable to Ebinur Lake waters. The results indicate that the Acolite-DSF algorithm has good consistency and high accuracy in the atmospheric correction of Landsat 8 and Sentinel 2 images. Extracting the atmospheric correction of Landsat 8 images found relative error at 0.3 in the Blue, Green, and Red bands and 0.5 in the NIR band. For comparison, the relative errors of Sentinel 2 in all bands are 0.3. Therefore, these four bands of Landsat 8 and Sentinel 2 data are recommended for temporal monitoring of water-environmental parameters in Ebinur Lake. Besides identifying the suitable atmospheric correction algorithm for Ebinur Lake, this study analyzed the atmospheric correction errors of common wavebands for remote sensing monitoring of water bodies, especially applicable for inland salt lakes of arid regions., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Liu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The Fast Fourier Transform (FFT) analysis of the activity concentration of radon and selected meteorological parameters was carried out at Department of Physics, Bangalore University, Bengaluru (12056'44"N, 77030'25″E, 840 m above MSL). All of the measured parameters, with the exception of pressure, showed a clear diurnal trend, which can be explained by the presence of typical atmospheric processes such as temperature inversion in the morning and greater vertical mixing in the afternoon. Radon's time series has a latent memory of sub-diurnal cycles, as shown via FFT analysis. The monthly average radon has higher levels of activity during winter months compared with monsoon and summer months. Days during the monsoon season had the lowest radon activity, which may be ascribed to the fact that less radon was being exhaled from the soil as a result of the rain. Radon was recorded at 8.06 ± 0.56 Bq/m3, temperature at 28.9 °C, humidity at 55.2% and pressure at 918 mbar., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Abstract The coupled data assimilation (CDA) system consisting of ocean, sea‐ice, and atmosphere data assimilation components with the Beijing Climate Center (BCC) Climate System Model has been developed to provide reliable analyses of the atmosphere, ocean, and sea‐ice states. It incorporates ocean temperature/salinity profiles, sea surface temperature, sea level height, and sea‐ice concentration observations at a daily frequency, and atmosphere reanalysis at a 6‐hourly frequency. Results show that the system is capable of realistically reproducing the climatology and variability of ocean, sea‐ice, and atmosphere. The performances in analyzing ocean component are comparable to those of well‐known ocean reanalyses that were once used to initialize the BCC model for climate predictions. A series of experiments with and without sea‐ice observations in the CDA framework are designed to explore the role of sea‐ice data assimilation (DA). The addition of sea‐ice DA exerts very small influence to the analysis of upper ocean temperature over the Arctic area, but leads to an evident reduction of temperature error in the upper 1000 m of ocean south of 60°S. Particularly, only the inclusion of sea‐ice DA can make the ocean/ocean‐atmosphere DA effective in providing skillful analysis in the high‐latitude Southern Ocean. Furthermore, we find that only on the basis of ocean DA, can the addition of sea‐ice concentration assimilation improve the analysis of tropical tropospheric atmosphere, along with a better analysis of mid‐ and high‐latitude stratospheric atmosphere. These results address the importance of coordination of sea‐ice observations and ocean observations in CDA.

The coupled data assimilation (CDA) system consisting of ocean, sea‐ice, and atmosphere data assimilation components with the Beijing Climate Center (BCC) Climate System Model has been developed to provide reliable analyses of the atmosphere, ocean, and sea‐ice states. It incorporates ocean temperature/salinity profiles, sea surface temperature, sea level height, and sea‐ice concentration observations at a daily frequency, and atmosphere reanalysis at a 6‐hourly frequency. Results show that the system is capable of realistically reproducing the climatology and variability of ocean, sea‐ice, and atmosphere. The performances in analyzing ocean component are comparable to those of well‐known ocean reanalyses that were once used to initialize the BCC model for climate predictions. A series of experiments with and without sea‐ice observations in the CDA framework are designed to explore the role of sea‐ice data assimilation (DA). The addition of sea‐ice DA exerts very small influence to the analysis of upper ocean temperature over the Arctic area, but leads to an evident reduction of temperature error in the upper 1000 m of ocean south of 60°S. Particularly, only the inclusion of sea‐ice DA can make the ocean/ocean‐atmosphere DA effective in providing skillful analysis in the high‐latitude Southern Ocean. Furthermore, we find that only on the basis of ocean DA, can the addition of sea‐ice concentration assimilation improve the analysis of tropical tropospheric atmosphere, along with a better analysis of mid‐ and high‐latitude stratospheric atmosphere. These results address the importance of coordination of sea‐ice observations and ocean observations in CDA. Plain Language Summary: Developing coupled data assimilation (CDA) technique has become an important task for many operational and research centers. Although CDA consisting of multiple assimilation components has made great progress in the past years, the impacts of each individual component, especially the sea‐ice data assimilation (DA), are not fully addressed yet. In this study, we have developed a CDA system and implemented a coordinated assimilation scheme of ocean, sea‐ice, and atmosphere data. This scheme shows reliable performances in analyzing the states of the ocean, sea‐ice, and atmosphere. A series of experiments are conducted to examine the impacts of sea‐ice DA on climate analysis. We stress that the importance of sea‐ice DA can be highlighted only in a multicomponent coordinated assimilation framework. On one hand, on the basis of ocean/ocean‐atmosphere DA, addition of sea‐ice DA can decrease the ocean temperature error in the upper 1000 m of the high‐latitude Southern Ocean. On the other hand, adding sea‐ice DA on the basis of ocean DA can improve the analysis of atmospheric variability in the tropical troposphere and mid‐ and high‐latitude stratosphere. These findings call for more attentions of operational model developers to comprehensively describe the role of sea‐ice DA in climate analysis and forecast. Key Points: A coupled data assimilation (DA) scheme with the BCC‐CSM is developed to give a reliable analysis of the ocean, sea‐ice, and atmosphereThe addition of sea‐ice DA on top of ocean‐atmosphere DA can reduce the upper 1000‐m temperature error in the high‐latitude Southern OceanAdding sea‐ice DA to ocean DA can improve the analysis of atmospheric variability in tropical troposphere [ABSTRACT FROM AUTHOR]

Surface ozone (O 3 ) is a crucial air pollutant that affects air quality, human health, agricultural production, and climate change. Studies on long-term O 3 variations and their influencing factors are essential for understanding O 3 pollution and its impact. Here, we conducted an analysis of long-term variations in O 3 during 2006-2022 at the Longfengshan Regional Atmosphere Background Station (LFS; 44.44°N, 127.36°E, 330.5 m a.s.l.) situated on the northeastern edge of the Northeast China Plains. The maximum daily 8-h average (MDA8) O 3 fluctuated substantially, with the annual MDA8 decreasing significantly during 2006-2015 (-0.62 ppb yr -1 , p < 0.05), jumping during 2015-2016 and increasing clearly during 2020-2022. Step multiple linear regression models for MDA8 were obtained using meteorological variables, to decompose anthropogenic and meteorological contributions to O 3 variations. Anthropogenic activities acted as the primary drivers of the long-term trends of MDA8 O 3 , contributing 73% of annual MDA8 O 3 variability, whereas meteorology played less important roles (27%). Elevated O 3 at LFS were primarily associated with airflows originating from the North China Plain, Northeast China Plain, and coastal areas of North China, primarily occurring during the warm months (May-October). Based on satellite products of NO 2 and HCHO columns, the O 3 photochemical regimes over LFS revealed NO x -limited throughout the period. NO 2 increased first, reaching peak in 2011, followed by substantial decrease; while HCHO exhibited significant increase, contributing to decreasing trend in MDA8 O 3 during 2006-2015. The plateauing NO 2 and decreasing HCHO may contribute to the increase in MDA8 O 3 in 2016. Subsequently, both NO 2 and HCHO exhibited notable fluctuations, leading to significant changes in O 3 . The study results fill the gap in the understanding of long-term O 3 trends in high-latitude areas in the Northeast China Plain and offer valuable insights for assessing the impact of O 3 on crop yields, forest productivity, and climate change., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, “Long-term variations in surface ozone at the Longfengshan Regional Atmosphere Background Station in Northeast China and related influencing factors”., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The recent and still controversial claim of phosphine detection in the venusian atmosphere has reignited consideration of whether microbial life might reside in its cloud layers. If microbial life were to exist within Venus' cloud deck, these microorganisms would have to be multi-extremophiles enclosed within the cloud aerosol particles. The most straightforward approach for resolving the question of their existence is to obtain samples of the cloud particles and analyze their interior. While developing technology has made sophisticated in situ analysis possible, more detailed information could be obtained by examining samples with instrumentation in dedicated ground-based facilities. Ultimately, therefore, Venus Cloud-level Sample Return Missions will likely be required to resolve the question of whether living organisms exist in the clouds of Venus. Two multiphase mission concepts are currently under development for combining in situ analyses with a sample return component. The Venus Life Finder architecture proposes collection of cloud particles in a compartment suspended from a balloon that floats for weeks at the desired altitude, while the Novel solUtion for Venus explOration and Lunar Exploitation (NUVOLE) concept involves a glider that cruises within the cloud deck for 1200 km collecting cloud aerosol particles through the key regions of interest. Both architectures propose a rocket-driven ascent with the acquired samples transported to a high venusian orbit as a prelude to returning to Earth or the Moon. Both future conceptual missions with their combined phases will contribute valuable information relative to the habitability of the clouds at Venus, but their fulfillment is decades away. We suggest that, in the meantime, a simplification of a glider cloud-level sample collection scenario could be accomplished in a shorter development time at a lower cost. Even if the cloud particles are not organic and show no evidence of living organisms, they would reveal critical insights about the natural history and evolution of Venus.

Black carbon (BC) constitutes a pivotal component of atmospheric aerosols, significantly impacting regional and global radiation balance, climate, and human health. In this study, we evaluated BC data in two prominent atmospheric composition reanalysis datasets: the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) and the Copernicus Atmosphere Monitoring Service (CAMS), and analyzed the causes of their deviations. This assessment is based on observational data collected from 34 monitoring stations across China from 2006 to 2022. Our research reveals a significant and consistent decline in BC concentrations within China, amounting to a reduction exceeding 67.33%. However, both MERRA-2 and CAMS reanalysis data fail to capture this declining trend. The average annual decrease of BC in MERRA-2 from 2006 to 2022 is only 0.06 μg/m 3 per year, while the BC concentration in CAMS even increased with an average annual value of 0.014 μg/m 3 per year. In 2022, MERRA-2 had overestimated BC concentration by 20% compared to observational data, while CAMS had overestimated it by approximately 66%. In the regional BC concentration analysis, the data quality of the reanalysis data is better in the South China (R M  = 0.59, R C  = 0.53), followed by the North China (R M  = 0.50, R C  = 0.42). Reanalysis BC data in Northwest China and the Tibetan Plateau are difficult to use for practical analysis due to their big difference with observation. In a comparison of the anthropogenic BC emissions inventory used in the two atmospheric composition reanalysis datasets with the Multi-resolution Emission Inventory model for Climate and air pollution research (MEIC) emissions inventory, we found that: Despite the significant decline in China's BC emissions, MERRA-2 still relies on the 2006 emissions inventory, while CAMS utilizes emission inventories that even show an increasing trend. These factors will undoubtedly lead to greater deviations between reanalysis and observational data., Competing Interests: Declaration of competing interest The authors 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 © 2023 Elsevier Ltd. All rights reserved.)

The genus Dellaglioa (D.) actually comprises two species, i.e., D. algida and the recently described species D. carnosa. Both species are adapted to cold and have been typically recovered from meat products. However, their importance has thus far been underestimated, since routine culture-based analysis failed to support their growth. Furthermore, their occurrence on meat packed under high-oxygen MA conditions (HiOx-MAP) is controversial because they have been described as being oxygen-sensitive. In this study, we focused on the targeted isolation of Dellaglioa spp. from HiOx-MAP meat samples and the characterization of our isolates regarding their adaption to HiOx-MAP conditions, their spoilage potential, as well as food safety aspects. We used a medium recently developed specifically for strains of this genus and investigated ten meat batches from seven different suppliers. Our study confirms that the occurrence of Dellaglioa spp. on HiOx-MAP meat is non-sporadic, reaching cell counts ranging from log 10 5.8-7.1 CFU/cm 2 at a late stage of chilled storage. Autochthonous Dellaglioa spp. and Leuconostoc (L.) gasicomitatum dominated the microbiota of the beef steaks with similar growth behavior. Our results suggest that Dellaglioa spp. benefits from the heme-dependent respiration of oxygen by L. gasicomitatum. Furthermore, whole genome analysis revealed the presence of genes predictively involved in oxidative stress defense, survival, and adaptation in meat environments. Moreover, we predict a weak aminogenic potential of D. algida strains. Tyramine production from tyrosine seems to be a species-specific characteristic of D. carnosa. The extent to which D. algida and D. carnosa occurrence is influenced by or even dependent on the composition of the entire microbiota remains to be investigated., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Victoria Werum reports financial support was provided by Technical University of Munich. Matthias Ehrmann reports a relationship with Technical University of Munich that includes: employment., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The presence of microalgae in the atmosphere raises health and environmental concerns. Despite recent scientific advances, our knowledge of the origins and dynamics of photosynthetic cells in relation to atmospheric processes is limited due to a lack of empirical data. To address this gap, we conducted a one-year survey, collecting and analyzing rainwater samples. This study proposes to investigate the temporal dynamics of photosynthetic cells based on their size in combination with a unique dataset of variables of interest: type of rain and its characteristics, local meteorology, concentrations of inorganic chemical species, and long-range air mass transport. The analysis of the biochemical composition of rainwater, along with its correlation with the origin of air masses using ions as tracers, provides evidence of the long-range transport of photosynthetic cells. Additionally, our study reveals distinct removal mechanisms from the atmosphere for photosynthetic cells depending on their size. Our results suggest that convective events with high-intensity rainfall led to the efficient removal of medium-sized photosynthetic cells (4-15 μm) from the atmosphere. However, removal mechanisms for small (<4 μm) and large-sized cells (>15 μm) are not influenced by microphysical rainfall characteristics and seem to be governed by different atmospheric processes: dry deposition is proposed to be a significant mechanism for the removal of large-sized photosynthetic cells, while small-sized cells detected in rain are correlated with the horizontal wind speed and duration of rainfall, particularly during stratiform events. This implies that the removal of photosynthetic cells from the atmosphere is strongly influenced by environmental variables, which are expected to vary in response to global change. Therefore, it is crucial to enhance the monitoring of photosynthetic cells in relation to atmospheric processes and investigate the potential impact of the dissemination of genetic material from distant sources on recipient ecosystems., Competing Interests: Declaration of competing interest The authors 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 © 2023 Elsevier B.V. All rights reserved.)

Cyanobacterial harmful algal blooms (cHABs) have the potential to adversely affect public health through the production of toxins such as microcystins, which consist of numerous molecularly distinct congeners. Microcystins have been observed in the atmosphere after emission from freshwater lakes, but little is known about the health effects of inhaling microcystins and the factors contributing to microcystin aerosolization. This study quantified total microcystin concentrations in water and aerosol samples collected around Grand Lake St. Marys (GLSM), Ohio. Microcystin concentrations in water samples collected on the same day ranged from 13 to 23 μg/L, dominated by the d-Asp 3 -MC-RR congener. In particulate matter <2.5 μm (PM 2.5 ), microcystin concentrations up to 156 pg/m 3 were detected; the microcystins were composed primarily of d-Asp 3 -MC-RR, with additional congeners (d-Asp 3 -MC-HtyR and d-Asp 3 -MC-LR) observed in a sample collected prior to a storm event. The PM size fraction containing the highest aerosolized MC concentration ranged from 0.44 to 2.5 μm. Analysis of total bacteria by qPCR targeting 16S rDNA revealed concentrations up to 9.4 × 10 4 gc/m 3 in aerosol samples (≤3 μm), while a marker specific to cyanobacteria was not detected in any aerosol samples. Concentrations of aerosolized microcystins varied even when concentrations in water were relatively constant, demonstrating the importance of meteorological conditions (wind speed and direction) and aerosol generation mechanism(s) (wave breaking, spillway, and aeration systems) when evaluating inhalation exposure to microcystins and subsequent impacts on human health.

In this study, the effect of modified atmosphere packaging with different gas mixtures on texture and muscle properties of Pacific white shrimp ( Litopenaeus vannamei ) during refrigerated storage was studied via texture profile, water holding capacity (WHC), protein properties (Ca 2+ -ATPase, TCA-soluble peptides, myofibrillar/sarcoplasmic protein content), and microbial counts. The results showed that the antibacterial effect of Modified atmosphere packaging (MAP) was correlated with the increase of CO 2 with the presence of low level of O 2 . Though MAP without O 2 had a higher whiteness value but also had higher bacterial counts and total volatile basic nitrogen (TVB-N) values compared with other MAP-groups. In general, a gas composition of 80% CO 2  + 5%O 2  + 15% N 2 treatment had lowest microbial counts and reduced TVB-N values by 22.85% in comparison with the control on day 10. However, MAP was found to have a complicated impact on muscle protein and texture of shrimp. 60% CO 2  + 5% O 2  + 35% N 2 and 40% CO 2  + 5% O 2  + 55% N 2 had an advantage in maintaining springiness and the content of myofibrillar/sarcoplasmic proteins. The correlation analysis showed that WHC had stronger relationship with springiness, resilience, myofibrillar protein content. Therefore, regarding the texture and protein properties, the concentration of CO 2 in MAP for Pacific white shrimp should not be higher than 60%., Competing Interests: DECLARATION OF CONFLICTING INTERESTSThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Emissions of odorous compounds are major contributors to public opposition when siting waste management facilities. Thus, it is essential to understand how to minimise the concentration of odour-causing chemicals in ambient air surrounding such facilities. Although the concentration of pollutants in the atmosphere is a function of meteorology, there is limited data on the atmospheric parameters that drive ambient air concentrations of odour-causing substances in settlements near waste management facilities. Here, we analysed how temperature, wind direction, wind speed, atmospheric pressure and humidity impact the concentrations of hydrogen sulphide (H 2 S) in the ambient air, a potentially toxic chemical and a chief contributor to noxious odours. The relative contribution of each variable was assessed using multivariate statistical analysis applied to an extensive data set of over 7,000 data points collected during 2021. Our results show that all tested atmospheric parameters significantly affected H 2 S concentrations in ambient air. Wind direction had the greatest impact on H 2 S concentrations, followed by temperature, humidity, atmospheric pressure and wind speed. Specifically, the concentration of H 2 S was positively correlated with humidity and atmospheric pressure and had a U-shaped correlation with temperature. Atmospheric variables were able to explain 15% of variation in H 2 S concentrations (R 2  = 15%), indicating the presence of other factors affecting H 2 S ambient air concentrations. Our study shows that proper consideration of atmospheric parameters, especially wind direction and temperatures, is of uttermost importance when siting waste management facilities. The conclusions are broadly applicable to odorous compounds near waste management facilities, so adverse effects to human health and the environment can be minimised., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Black carbon (BC) has a significantly negative impact on air quality, climate and human health. Here we investigated the sources and health effects of BC in urban area of the Pearl River Delta (PRD) based on online data measured by Aerodyne soot particle high-resolution time of flight aerosol mass spectrometer (SP-AMS). In urban PRD, BC particles mainly came from vehicle emissions especially heavy-duty vehicle exhausts (contributing 42.9 % of total BC mass concentration), long-range transport (27.6 %), and aged biomass combustion emissions (22.3 %). Indicated by source analysis using simultaneous aethalometer data, BC associated with local secondary oxidation and transport may also be originated from fossil fuel combustion, especially traffic sources in urban and surrounding areas. Size-resolved BC mass concentrations provided by SP-AMS, for the first time to our best knowledge, were used to calculate BC deposition in the human respiratory tract (HRT) of different populations (children, adults, and the elderly) by the Multiple-Path Particle Dosimetry (MPPD) model. We found that submicron BC was deposited more in the pulmonary (P) region (49.0-53.2 % of the total BC deposition dose), while less in the tracheobronchial (TB, 35.6-37.2 %) and head (HA, 11.2-13.8 %) regions. Adults suffered the highest BC deposition (1.19 μg day -1 ) than the elderly (1.09 μg day -1 ) and children (0.25 μg day -1 ). BC deposition rate was greater at night (especially 18:00-24:00) than during the daytime. The maximum deposition in the HRT was found for BC particles around 100 nm, mainly in deeper respiratory regions (TB and P), which may cause more serious health effects. Adults and the elderly group are confronted with the notable carcinogenic risk of BC in the urban PRD, up to 29 times higher than the threshold. Our study emphasizes the need to control BC pollution in the urban area, especially nighttime vehicle emissions., Competing Interests: Declaration of competing interest The authors 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 © 2023 Elsevier B.V. All rights reserved.)

Marine biological activities make a non-negligible contribution to atmospheric aerosols, leading to potential impacts on the regional atmospheric environment and climate. The eastern China seas are highly productive with significant emissions of biogenic substances, but the spatiotemporal variations of marine biogenic aerosols are not well known. Air mass exposure to chlorophyll a (AEC) can be used to indicate the influence of biogenic sources on the atmosphere to a certain degree. In this study, the 12 year (2009-2020) daily AEC were calculated over the eastern China seas, showing the spatial and seasonal patterns of marine biogenic influence intensity which were co-controlled by surface phytoplankton biomass and boundary layer height. By combining the AEC values, relevant meteorological parameters, and extensive observations of a typical biogenic secondary aerosol component, methanesulfonate (MSA), a parameterization scheme for MSA simulation was successfully constructed. This AEC-based approach with observation constraints provides a new insight into the distribution of marine biogenic aerosols. Meanwhile, the wintertime air mass retention over land exhibited a significant decrease, showing a decadal weakening trend of terrestrial transport, which is probably related to the weakening of the East Asian winter monsoon. Thus, marine biogenic aerosols may play an increasingly important role in the studied region.

East Africa's air pollution levels are deteriorating due to anthropogenic and biomass burning emissions and unfavorable weather conditions. This study investigates the changes and influencing factors of air pollution in East Africa from 2001 to 2021. The study found that air pollution in the region is heterogeneous, with increasing trends observed in pollution hot spots (PHS) while it decreased in pollution cold spots (PCS). The analysis identified four major pollution periods: High Pollution period 1, Low Pollution period 1, High Pollution period 2, and Low Pollution period 2, which occur during Feb-Mar, Apr-May, Jun-Aug and Oct-Nov, respectively. The study also revealed that long range transport of pollutants to the study area is primarily influenced by distant sources from the eastern, western, southern, and northern part of the continent. The seasonal meteorological conditions, such as high sea level pressure in the upper latitudes, cold air masses from the northern hemisphere, dry vegetation, and a dry and less humid atmosphere from boreal winter, further impact the transport of pollutants. The concentrations of pollutants were found to be influenced by climate factors, such as temperature, precipitation, and wind patterns. The study identified different pollution patterns in different seasons, with some areas having minimal anthropogenic pollution due to high vegetation vigor and moderate precipitation. Using Ordinary Least Square (OLS) regression and Detrended Fluctuation Analysis (DFA), the study quantified the magnitude of spatial variation in air pollution. The OLS trends indicated that 66 % of pixels exhibited decreasing trends while 34 % showed increasing trends, and DFA results indicating that 36 %, 15 %, and 49 % of pixels exhibited anti-persistence, random, and persistence in air pollution, respectively. Areas in the region experiencing increasing or decreasing trends in air pollution, which can be used to prioritize interventions and resources for improving air quality, were also highlighted. It also identifies the driving forces behind air pollution trends, such as anthropogenic or biomass burning, which can inform policy decisions aimed at reducing air pollution emissions from these sources. The findings on the persistence, reversibility, and variability of air pollution can inform the development of long-term policies for improving air quality and protecting public health., Competing Interests: Declaration of competing interest Authors declare no conflict of Interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The stability of the atmosphere plays an important role in changes in air pollutant concentrations. Stable atmospheric conditions cause pollutant concentrations to reach high values, which degrades the air quality in a particular region. This study aims to reveal the relationship between atmospheric stability indices/parameters (thermodynamic indices) and changes in air pollutant concentrations. Pollutant concentrations of PM 10 , PM 2.5 , SO 2 , NO 2 , CO, and O 3 were statistically analyzed for a 10-year (2013-2022) period for nine air quality stations located in the megacity Istanbul. Based on national and international air quality standards, 145 episode days were determined for the days when these parameters exceeded the threshold values. Five stability indices (Showalter Index - SI, Lifted Index - LI, Severe Weather Index - SWEAT, K Index - KI, Totals Totals Index - TTI), and three stability parameters (Convective Available Potential Energy - CAPE, Convective Inhibition - CIN, Bulk Richardson Number - BRN) were used to determine the stability of the atmosphere for episode days. It has been found that in cases where air pollutant concentrations are high, the stability parameters reveal the stability of the atmosphere better than the stability indices. It was also found that there was at least one vertical inversion layer on 122 of the 145 episode days, these layers mostly (84%) occurred between the surface and 850 hPa levels, and the layer thicknesses were mostly between 0-250 m (84%)., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Ambient fine particulate matter (PM 2.5 ) has severe adverse health impacts, making it crucial to reduce PM 2.5 exposure for public health. Meteorological and emissions factors, which considerably affect the PM 2.5 concentrations in the atmosphere, vary substantially under different climate change scenarios. In this work, global PM 2.5 concentrations from 2021 to 2100 were generated by combining the deep learning technique, reanalysis data, emission data, and bias-corrected CMIP6 future climate scenario data. Based on the estimated PM 2.5 concentrations, the future premature mortality burden was assessed using the Global Exposure Mortality Model. Our results reveal that SSP3-7.0 scenario is associated with the highest PM 2.5 exposure, with a global concentration of 34.5 μg/m 3 in 2100, while SSP1-2.6 scenario has the lowest exposure, with an estimated of 15.7 μg/m 3 in 2100. PM 2.5 -related deaths for individuals under 75 years will decrease by 16.3 and 10.5% under SSP1-2.6 and SSP5-8.5, respectively, from 2030s to 2090s. However, premature mortality for elderly individuals (>75 years) will increase, causing the contrary trends of improved air quality and increased total PM 2.5 -related deaths in the four SSPs. Our results emphasize the need for stronger air pollution mitigation measures to offset the future burden posed by population age.

A simple visual and tristimulus colorimetric method (three-dimensional system CIE-L*a*b*) for the determination of trace amounts of hydrogen cyanide in air has been developed. The method is based on the suction of hydrogen cyanide through a chlorinating cartridge where cyanogen chloride is formed, which is further driven to an indicator disc made of a modified cotton fabric. This indicator disc is placed into an adapter. Prior to analysis, the disc is saturated with a chromogenic reagent, a solution of 5,5-dimethyl-1,3-cyclohexanedione (dimedone) and 4-benzylpyridine in ethanol. In the presence of hydrogen cyanide (cyanogen chloride), a pink coloration emerges on the indicator disc, the intensity of which is evaluated either visually or by use of a tristimulus colorimeter. The detection limit is 0.1 mg m-3. The method is mainly suitable for mobile field analyses. It was applied for the CHP-5 chemical agent detector introduced into the equipment of the Czech Army corps.

Observational evidence shows the ubiquitous presence of ocean-emitted short-lived halogens in the global atmosphere 1-3 . Natural emissions of these chemical compounds have been anthropogenically amplified since pre-industrial times 4-6 , while, in addition, anthropogenic short-lived halocarbons are currently being emitted to the atmosphere 7,8 . Despite their widespread distribution in the atmosphere, the combined impact of these species on Earth's radiative balance remains unknown. Here we show that short-lived halogens exert a substantial indirect cooling effect at present (-0.13 ± 0.03 watts per square metre) that arises from halogen-mediated radiative perturbations of ozone (-0.24 ± 0.02 watts per square metre), compensated by those from methane (+0.09 ± 0.01 watts per square metre), aerosols (+0.03 ± 0.01 watts per square metre) and stratospheric water vapour (+0.011 ± 0.001 watts per square metre). Importantly, this substantial cooling effect has increased since 1750 by -0.05 ± 0.03 watts per square metre (61 per cent), driven by the anthropogenic amplification of natural halogen emissions, and is projected to change further (18-31 per cent by 2100) depending on climate warming projections and socioeconomic development. We conclude that the indirect radiative effect due to short-lived halogens should now be incorporated into climate models to provide a more realistic natural baseline of Earth's climate system., (© 2023. The Author(s).)

A cataclysmic submarine volcano at Hunga Tonga-HungaHa'apai (HTHH) near Tonga, erupted violently on 15 January 2022, which injected a plume of ash cloud soaring into the upper atmosphere. In this study, we examined the regional transportation and potential influence of atmospheric aerosols triggered by HTHH volcano, based on active and passive satellite products, ground-based observations, multi-source reanalysis datasets and atmospheric radiative transfer model. The results indicated that about 0.7 Tg (1 Tg = 10 9  kg) sulfur dioxide (SO 2 ) gas were emitted into stratosphere from the HTHH volcano, and were lifted to an altitude of 30 km. The regional averaged SO 2 columnar content over the western Tonga increased by 10-36 Dobson Units (DU), and the mean aerosol optical thickness (AOT) retrieved from satellite products increased to 0.25-0.34. The stratospheric AOT values caused by HTHH emissions increased to 0.03, 0.20, and 0.23 on 16, 17, and 19 January, respectively, accounting for 1.5%, 21.9%, and 31.1% of total AOT. Ground-based observations also showed an AOT increase of 0.25-0.43, with the maximum daily average of 0.46-0.71 appeared on 17 January. The volcanic aerosols were remarkably dominated by fine-mode particles and posed strong light-scattering and hygroscopic abilities. Consequently, the mean downward surface net shortwave radiative flux was reduced by 2.45-11.9 Wm -2 on different regional scales, and the surface temperature decreased by 0.16-0.42 K. The maximum aerosol extinction coefficient was 0.51 km -1 appeared at 27 km, which resulted in an instantaneous shortwave heating rate of 1.80 Khour -1 . These volcanic materials stayed stable in the stratosphere and completed one circle around the earth within 15 days. This would exert a profound influence on the energy budget, water vapor and ozone exchange in the stratosphere, which deserves to be further studied., Competing Interests: Declaration of competing interest The authors 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 © 2023 Elsevier Ltd. All rights reserved.)

Aerosols' influences on Earth's climate have been documented by several authors. This ranges from scattering and reflecting of shortwave radiation (direct effect) which is also regarded as the "Whitehouse Effect," to the ability to act as condensation nuclei (indirect effect) which results in cloud droplet formation. This broad summary of aerosol's effect on earth's climate has in turn affected some other weather variables either positively or negatively depending on people's perspectives. This work was done in a view to ascertaining some of these claims by determining the statistical significance of some certain aerosol's relationships with some selected weather variables. This was done over six (6) stations across the West African region to represent the climatic zones from the rainforest around the coasts to the desert of the Sahel. Data used consist of aerosol types (biomass burning, carbonaceous, dust, and PM 2.5 ) and climatic types (convective precipitation, wind speed, and water vapor) over a period of 30 years, with the python and ferret programs explicitly used for the graphical analyses. Climatologically, locations close to the point source seem to record more of the presence of the pollutants than the farthest ones. Results indicated that aerosols were more pronounced in the dry months of NDJF over the rainforest region depending on the latitudinal position of the location. The relationship result showed a negative correlation between convective precipitation and aerosols, except carbonaceous. But the strongest relationship can be found between water vapor and the selected aerosol types., (© 2023. The Author(s).)

Multiphase oxidative aging is a ubiquitous process for atmospheric organic aerosols (OA). But its kinetics was often found to be slow in previous laboratory studies where high hydroxyl radical concentrations ([ • OH]) were used. In this study, we performed heterogeneous oxidation experiments of several model OA systems under varied aging timescales and gas-phase [ • OH]. Our results suggest that OA heterogeneous oxidation may be 2-3 orders of magnitude faster when [ • OH] is decreased from typical laboratory flow tube conditions to atmospheric levels. Direct laboratory mass spectrometry measurements coupled with kinetic simulations suggest that an intermolecular autoxidation mechanism mediated by particle-phase peroxy radicals greatly accelerates OA oxidation, with enhanced formation of organic hydroperoxides, alcohols, and fragmentation products. With autoxidation, we estimate that the OA oxidation timescale in the atmosphere may be from less than a day to several days. Thus, OA oxidative aging can have greater atmospheric impacts than previously expected. Furthermore, our findings reveal the nature of heterogeneous aerosol oxidation chemistry in the atmosphere and help improve the understanding and prediction of atmospheric OA aging and composition evolution.

By accounting for most of the poleward atmospheric heat and moisture transport in the tropics, the Hadley circulation largely affects the latitudinal patterns of precipitation and temperature at low latitudes. To increase our preparednesses for human-induced climate change, it is thus critical to accurately assess the response of the Hadley circulation to anthropogenic emissions 1-3 . However, at present, there is a large uncertainty in recent Northern Hemisphere Hadley circulation strength changes 4 . Not only do climate models simulate a weakening of the circulation 5 , whereas atmospheric reanalyses mostly show an intensification of the circulation 4-8 , but atmospheric reanalyses were found to have artificial biases in the strength of the circulation 5 , resulting in unknown impacts of human emissions on recent Hadley circulation changes. Here we constrain the recent changes in the Hadley circulation using sea-level pressure measurements and show that, in agreement with the latest suite of climate models, the circulation has considerably weakened over recent decades. We further show that the weakening of the circulation is attributable to anthropogenic emissions, which increases our confidence in human-induced tropical climate change projections. Given the large climate impacts of the circulation at low latitudes, the recent human-induced weakening of the flow suggests wider consequences for the regional tropical-subtropical climate., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Air is a medium for dispersal of environmental DNA (eDNA) carried in bioaerosols, yet the atmosphere is mostly unexplored as a source of genetic material encompassing all domains of life. In this study, we designed and deployed a robust, sterilizable hardware system for airborne nucleic acid capture featuring active filtration of a quantifiable, controllable volume of air and a high-integrity chamber to protect the sample from loss or contamination. We used our hardware system on an aircraft across multiple height transects over major aerosolization sources to collect air eDNA, coupled with high-throughput amplicon sequencing using multiple DNA metabarcoding markers targeting bacteria, plants, and vertebrates to test the hypothesis of large-scale genetic presence of these bioaerosols throughout the planetary boundary layer in the lower troposphere. Here, we demonstrate that the multi-taxa DNA assemblages inventoried up to 2,500 m using our airplane-mounted hardware system are reflective of major aerosolization sources in the survey area and show previously unreported airborne species detections ( i.e ., Allium sativum L). We also pioneer an aerial survey flight grid standardized for atmospheric sampling of genetic material and aeroallergens using a light aircraft and limited resources. Our results show that air eDNA from terrestrial bacteria, plants, and vertebrates is detectable up to high altitude using our airborne air sampler and demonstrate the usefulness of light aircraft in monitoring campaigns. However, our work also underscores the need for improved marker choices and reference databases for species in the air column, particularly eukaryotes. Taken together, our findings reveal strong connectivity or mixing of terrestrial-associated eDNA from ground level aerosolization sources and the atmosphere, and we recommend that parameters and indices considering lifting action, atmospheric instability, and potential for convection be incorporated in future surveys for air eDNA. Overall, this work establishes a foundation for light aircraft campaigns to comprehensively and economically inventory bioaerosol emissions and impacts at scale, enabling transformative future opportunities in airborne DNA technology., Competing Interests: Kimberly L Métris and Jérémy Métris are co-founders of Airborne Science, the company that designed and built the high integrity probe and supporting system used in this work. A patent application has been filed for the high-integrity capture system. The authors and company did not receive financial support or compensation for this study., (© 2023 Métris and Métris.)

Atmospheric mercury (Hg) cycling in polluted coastal atmosphere is complicated and not fully understood. Here, we present measurements of total gaseous mercury (TGM) monitored at a coastal mountaintop in Hong Kong downwind of mainland China. Sharp TGM peaks during cold front passages were frequently observed due to Asian pollution outflow with typical TGM/CO slopes of 6.8 ± 2.2 pg m -3 ppbv -1 . Contrary to the daytime maximums of other air pollutants, TGM exhibited a distinct diurnal variation with a midday minimum. Moreover, we observed four cases of extremely fast TGM depletion after sunrise, during which TGM concentrations rapidly dipped to 0.3-0.6 ng m -3 accompanied by other pollutants on the rise. Simulated meteorological fields revealed that morning upslope flow transporting anthropogenically polluted but TGM-depleted air masses from the mixed layer caused morning TGM depletion at the mountaintop location. The TGM-depleted air masses were hypothesized to result mainly from fast photooxidation of Hg after sunrise with minor contributions from dry deposition (5.0%) and nocturnal oxidation (0.6%). A bromine-induced two-step oxidation mechanism involving abundant pollutants (NO 2 , O 3 , etc.) was estimated to play a dominant role, contributing 55%-60% of depleted TGM and requiring 0.20-0.26 pptv Br, an amount potentially available through sea salt aerosol debromination. Our findings suggest significant effects of the interaction between anthropogenic pollution and marine halogen chemistry on atmospheric Hg cycling in the coastal areas.

To better understand the formation process of biogenic and anthropogenic secondary organic aerosols (BSOA and ASOA) in the marine atmosphere under the background of global warming, aerosol samples were collected over three summers (i.e., 2014, 2016 and 2018) from the Bering Sea (BS) to the western North Pacific (WNP). The results showed that temporally, atmospheric concentrations of isoprene-derived SOA (SOA I ) tracers were the lowest in 2014 regardless of the marine region, while atmospheric concentrations of monoterpenes-derived SOA (SOA M ) tracers in this year were the highest and the aerosols were more aged than those in the other two years. In comparison, the concentrations of β-caryophyllene-derived and toluene-derived SOA (SOA C and SOA A ) tracers were relatively low overall. Spatially, the concentrations of SOA tracers were significantly higher over the WNP than over the BS, with SOA tracers over the BS mainly coming from marine sources, while the WNP was strongly influenced by terrestrial inputs. In particular, for land-influenced samples from the WNP, NO x -channel products of SOA I were more dependent on O 3 and SO 2 relative to HO 2 -channel product, and the high atmospheric oxidation capacity and SO 2 could promote the formation of later-generation SOA M products. The extent of terrestrial influence was further quantified using a principal component analysis (PCA)-generalized additive model (GAM), which showed that terrestrial emissions explained more than half of the BSOA tracers' concentrations and contributed almost all of the ASOA tracer. In addition, the assessment of secondary organic carbon (SOC) highlighted the key role of anthropogenic activities in organic carbon levels in offshore areas. Our study revealed significant contributions of terrestrial natural and anthropogenic sources to different SOA over the WNP, and these relevant findings help improve knowledge about SOA in the marine atmosphere., Competing Interests: Declaration of competing interest The authors 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 © 2022 Elsevier B.V. All rights reserved.)

There are many questions regarding the behavior of mercury in the sea-atmosphere system of the northwestern Pacific. Continuous underway measurements of atmospheric gaseous elemental mercury (GEM) and measurements of sea-air GEM evasion fluxes were carried out in the marginal seas of northwestern Pacific from the South China Sea to the Sea of Okhotsk in fall-winter 2019. The median GEM concentration (1.1 ng/m 3 ) was lower than both the background value and the averages previously observed in these areas. A latitudinal gradient of atmospheric GEM and GEM evasion fluxes with maximum values at southern latitudes was found. The following areas have been identified as potential source areas: the Kurill area of the Pacific Ocean Northeast China, Korean Peninsula, and the territory from the southwest coast of the Yellow Sea to the south of Indochina. Seasonal variations were observed in the Sea of Japan and East China Sea with higher GEM concentrations in winter than in fall. Our data and analysis of published data showed significant relationships between GEM evasion fluxes, latitude and sea surface temperature (SST). It seems that on a global scale, along with the GEM gradient between water and atmosphere, SST is the most significant parameter for sea-air GEM evasion fluxes., Competing Interests: Declaration of competing interest The authors 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 © 2022 Elsevier B.V. All rights reserved.)

In this study, we combined the measured bulk particle number concentration (N CN ), particle number size distribution (PNSD) and bulk cloud condensation nuclei concentration (N CCN ) at various supersaturation (SS) levels to investigate competitive activation of aerosols in the marine atmospheres over the marginal seas of China during two winter campaigns Campaign A (December 9-19, 2019) and Campaign B (December 28, 2019-January 16, 2020). During the two campaigns, we observed various categories of aerosols, i.e., long-range transport continental aerosols, clean marine aerosols, grown new particles ranging from nucleation mode to larger sizes, and grown pre-existing particles ranging from Aitken mode to accumulation mode size, etc. We found that the measured N CCN increased by only approximately 30 % with increases in SS levels from 0.2 % to 1.0 %, e.g., (1.8 ± 1.4) × 10 3 cm -3 at SS = 0.2 % and (2.4 ± 1.4) × 10 3 cm -3 at SS = 1.0 % during Campaign A. We further calculated the hygroscopicity parameter kappa (κ) by combining simultaneously measured PNSD and bulk N CCN to explore the causes. The calculated κ values were below 0.1 at SS = 0.4 % during the 72 % (or 88 %) period of Campaign A (or Campaign B). When κ values below 0.1 (or 0.2) were excluded, the remaining κ values were apparently reasonable, with an average of 0.22 (or 0.36) and a standard deviation of 0.10 (or 0.21) at SS = 0.4 % during Campaign A (or Campaign B). The unexpectedly lower κ values were discussed in terms of competitive activation of aerosols in marine atmospheres together with its net contribution to lowering the measured bulk N CCN below the expected value., Competing Interests: Declaration of competing interest The authors 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 © 2022 Elsevier B.V. All rights reserved.)

Background: Performing back trajectory and forward trajectory using the Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT) is a reliable approach for assessing particle transport after release among mid-field atmospheric models. HYSPLIT has an externally facing online interface that allows non-expert users to run the model trajectories without requiring extensive training or programming. However, the existing HYSPLIT interface is limited if simulations have a large amount of meteorological data and timesteps that are not coincident. The objective of this study is to design and develop a more robust tool to rapidly evaluate hazard transport conditions and to perform risk analysis, while still maintaining an intuitive and user-friendly interface., Methods: HYSPLIT calculates forward and backward trajectories of particles based on wind speed, wind direction, and the corresponding location, timestamp, and Pasquill stability classes of the regions of the atmosphere in terms of the wind speed, the amount of solar radiation, and the fractional cloud cover. The computed particle transport trajectories, combined with the online Proton Transfer Reaction-Mass Spectrometry (PTR-MS) data (https://figshare.com/articles/dataset/ARL&#95;Data&#95;from&#95;PROS&#95;station&#95;at&#95;Hanford&#95;site/19993964), can be used to identify and quantify the sources and affected area of the hazardous chemicals' emission using the potential source distribution function (PSDF). PSDF is an improved statistical function based on the well-known potential source contribution function (PSCF) in establishing the air pollutant source and receptor relationship. Performing this analysis requires a range of meteorological and pollutant concentration measurements to be statistically meaningful. The existing HYSPLIT graphical user interface (GUI) does not easily permit computations of trajectories of a dataset of meteorological data in high temporal frequency. To improve the performance of HYSPLIT computations from a large dataset and enhance risk analysis of the accidental release of material at risk, a geospatial risk analysis tool (GRAT-GUI) is created to allow large data sets to be processed instantaneously and to provide ease of visualization., Results: The GRAT-GUI is a native desktop-based application and can be run in any Windows 10 system without any internet access requirements, thus providing a secure way to process large meteorological datasets even on a standalone computer. GRAT-GUI has features to import, integrate, and convert meteorological data with various formats for hazardous chemical emission source identification and risk analysis as a self-explanatory user interface. The tool is available at https://figshare.com/articles/software/GRAT/19426742., Competing Interests: The authors declare there are no competing interests., (©2023 Hou et al.)

In order to conduct more thorough research on the structural characteristics of the atmosphere and the distribution and transmission of atmospheric pollution, the use of remote sensing technology for multi-dimensional detection of the atmosphere is needed. A light-weight, low-volume, low-cost, easy-to-use and low-maintenance mini Infrared Lidar (mIRLidar) sensor is developed for the first time. The model of lidar is established, and the key optical parameters of the mIRLidar are optimized through simulation, in which wavelength of laser, energy of pulse laser, diameter of telescope, field of view (FOV), and bandwidth of filter are included. The volume and weight of the lidar system are effectively reduced through optimizing the structural design and designing a temperature control system to ensure the stable operation of the core components. The mIRLidar system involved a 1064 nm laser (the pulse laser energy 15 μJ, the repetition frequency 5 kHz), a 100 mm aperture telescope (the FOV 1.5 mrad), a 0.5 nm bandwidth of filter and an APD, where the lidar has a volume of 200 mm × 200 mm × 420 mm and weighs about 13.5 kg. It is shown that the lidar can effectively detect three-dimensional distribution and transmission of aerosol and atmospheric pollution within a 5 km detection range, from Horizontal, scanning and navigational atmospheric measurements. It has great potential in the field of meteorological research and environmental monitoring.

Introduction: The concentrations of particulate and gaseous Polycyclic Hydrocarbons Carbon (PAHs) were determined in the urban atmosphere of Delhi in different seasons (winter, summer, and monsoon)., Methodology: The samples were collected using instrument air metric (particulate phase) and charcoal tube (gaseous phase) and analyzed through Gas chromatography. The principal component and correlation were used to identify the sources of particulate and gaseous PAHs during different seasons., Results and Discussion: The mean concentration of the sum of total PAHs (TPAHs) for particulate and gaseous phases at all the sites were found to be higher in the winter season (165.14 ± 50.44 ng/m 3 and 65.73 ± 16.84 ng/m 3 ) than in the summer season (134.08 ± 35.0 ng/m 3 and 43.43 ± 9.59 ng/m 3 ), whereas in the monsoon season the concentration was least (68.15 ± 18.25 ng/m 3 and 37.63 1 13.62 ng/m 3 ). The principal component analysis (PCA) results revealed that seasonal variations of PAHs accounted for over 86.9%, 84.5%, and 94.5% for the summer, monsoon, and winter seasons, respectively. The strong and positive correlation coefficients were observed between B(ghi)P and DahA (0.922), B(a)P and IcdP (0.857), and B(a)P and DahA (0.821), which indicated the common source emissions of PAHs. In addition to this, the correlation between Nap and Flu, Flu and Flt, B(a)P, and IcdP showed moderate to high correlation ranging from 0.68 to 0.75 for the particulate phase PAHs. The carcinogenic health risk values for gaseous and particulate phase PAHs at all sites were calculated to be 4.53 × 10 -6 , 2.36 × 10-5 for children, and 1.22 × 10 -5 , 6.35 × 10 -5 for adults, respectively. The carcinogenic health risk for current results was found to be relatively higher than the prescribed standard of the Central Pollution Control Board, India (1.0 × 10 -6 )., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Singh, Zughaibi, Alharthy, Al-Asmari and Rahman.)

Biogenic secondary organic aerosols (BSOA) are important components of the remote marine atmosphere. However, the response of BSOA changes to sea ice reduction over the Arctic Ocean remains unclear. Here we investigated isoprene and monoterpenes secondary organic aerosol (SOAI and SOAM) tracers in three years of summer aerosol samples collected from the Arctic Ocean atmosphere. The results indicated that methyltetrols were the most abundant SOAI tracers, while the main oxidation products of monoterpenes varied over the years owing to different aerosol aging. The results of the principal component analysis (PCA)-generalized additive model (GAM) combined with correlation analysis suggested that SOAI tracers were mainly generated by the oxidation of isoprene from marine emissions, while SOAM tracers were probably more influenced by terrestrial transport. Estimation of secondary organic carbon (SOC) indicated that monoterpenes oxidation contributed more than isoprene and that sea ice changes had a relatively small effect on biogenic SOC concentration levels. Our study quantified the contribution of influencing factors to the atmospheric concentration of BSOA tracers in the Arctic Ocean, and showed that there were differences in the sources of precursors for different BSOA. Hence, our findings have contributed to a better understanding of the characteristics, sources and formation of SOA in the atmosphere of the Arctic Ocean., Competing Interests: Declaration of competing interest The authors 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 © 2022 Elsevier B.V. All rights reserved.)

Hydrogen (H 2 ) is expected to play a crucial role in reducing greenhouse gas emissions. However, hydrogen losses to the atmosphere impact atmospheric chemistry, including positive feedback on methane (CH 4 ), the second most important greenhouse gas. Here we investigate through a minimalist model the response of atmospheric methane to fossil fuel displacement by hydrogen. We find that CH 4 concentration may increase or decrease depending on the amount of hydrogen lost to the atmosphere and the methane emissions associated with hydrogen production. Green H 2 can mitigate atmospheric methane if hydrogen losses throughout the value chain are below 9 ± 3%. Blue H 2 can reduce methane emissions only if methane losses are below 1%. We address and discuss the main uncertainties in our results and the implications for the decarbonization of the energy sector., (© 2022. The Author(s).)

Black carbon (BC) and carbon monoxide (CO) at different model levels from the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis were comprehensively evaluated against observations performed simultaneously on both surface and mountain sites in winter and summer in the North China Plain for the first time. CAMS could capture the seasonal difference in BC and CO emission on both sites but showed significant and persistent biases. Biases were high on the surface site and low on the mountain site for both seasons, implying the uncertainties in emission inventories used in the CAMS reanalysis which may have more influence near source. Biases were reduced and the correlation coefficient of CAMS BC with observed BC increased when two datasets were compared on a daily basis, which suggests daily or longer time averaged CAMS BC could be more suitable for trend analysis. Although CAMS could generally reproduce the distinct diurnal variation of BC and CO on both sites, the inaccurate representation of the daily evolution of planetary boundary layer (PBL) in model may bring more uncertainties to the concentration biases on surface from midnight to early morning. BC hydrophilic ratio from CAMS displayed large biases compared to observations with no seasonal difference on both sites, which was probably resulted from the initial emission state of BC hygroscopicity for all source types in model. Uncertainties in the removal processes and the simplified aging processes in model could further induce uncertainty in modelling BC hydrophilic ratio in the CAMS. These results could not only be referenced for the improvement on CAMS reanalysis but also facilitate model or trend analysis of BC and CO pollution by utilizing the CAMS reanalysis product from both short- and long-term perspectives, which will be beneficial to both the mitigation and policy-making on primary emissions in China., Competing Interests: Declaration of competing interest The authors 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 © 2022 Elsevier Ltd. All rights reserved.)

Studies show that forests are one of the main recreational destinations. This can be explained by their beneficial effects on the health of their visitors, which can be attributed to compounds from the terpene group. The aim of this research was to determine the chemical composition of air in the interiors of Nemoral Scots pine forests and submountainous beech forests, with the determination of compounds of the terpene group. Samples of organic compounds present in the air were collected with the use of Tenax TA sorbent tubes. The process of separation, identification, and determination of the extracted organic compounds was carried out with the use of the gas chromatography technique integrated with a flame ionization detector. Additional identification of the extracted compounds was carried out with the use of GC coupled with mass spectrometry. The most abundant group of compounds was the aliphatic hydrocarbons, both saturated (linear and branched) and unsaturated (terpenes). Carbonyl compounds were also found in the collected samples, but they constituted no more than 10% of all compounds present on the chromatograms. The concentrations of terpenes and terpenoids in the forest atmosphere varied from 10 to 74 µg·m -3 , representing on average 33% of the total volatile organic compounds.

A coordinated observational and modelling campaign targeting biogenic aerosols in the air was performed during spring 2021 at two locations in Northern Europe: Helsinki (Finland) and Siauliai (Lithuania), approximately 500 km from each other in north-south direction. The campaign started on March 1, 2021 in Siauliai (12 March in Helsinki) and continued till mid-May in Siauliai (end of May in Helsinki), thus recording the transition of the atmospheric biogenic aerosols profile from winter to summer. The observations included a variety of samplers working on different principles. The core of the program was based on 2- and 2.4--hourly sampling in Helsinki and Siauliai, respectively, with sticky slides (Hirst 24-h trap in Helsinki, Rapid-E slides in Siauliai). The slides were subsequently processed extracting the DNA from the collected aerosols, which was further sequenced using the 3-rd generation sequencing technology. The core sampling was accompanied with daily and daytime sampling using standard filter collectors. The hourly aerosol concentrations at the Helsinki monitoring site were obtained with a Poleno flow cytometer, which could recognize some of the aerosol types. The sampling campaign was supported by numerical modelling. For every sample, SILAM model was applied to calculate its footprint and to predict anthropogenic and natural aerosol concentrations, at both observation sites. The first results confirmed the feasibility of the DNA collection by the applied techniques: all but one delivered sufficient amount of DNA for the following analysis, in over 40% of the cases sufficient for direct DNA sequencing without the PCR step. A substantial variability of the DNA yield has been noticed, generally not following the diurnal variations of the total-aerosol concentrations, which themselves showed variability not related to daytime. An expected upward trend of the biological material amount towards summer was observed but the day-to-day variability was large. The campaign DNA analysis produced the first high-resolution dataset of bioaerosol composition in the North-European spring. It also highlighted the deficiency of generic DNA databases in applications to atmospheric biota: about 40% of samples were not identified with standard bioinformatic methods., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

This study aims to develop a 1D model that makes it possible to calculate the daily total 7 Be wet deposition flux. For this purpose, long-term (2015-2021), high-frequency (daily) and time-synchronized series of observations of 7 Be wet deposition flux and its atmospheric activity concentration are analyzed in this paper. Daily mean 7 Be activity concentration in the atmosphere, daily total 7 Be wet deposition flux and mean 7 Be activity concentration, washout ratio, deposition velocity and scavenging coefficient with individual precipitation events lie in the range of 0.1-17 mBq m -3 , 0.8-117.2 Bq m -2 d -1 , 0.4-11.3 Bq L -1 , 331-3799, 0.2-24.7 cm s -1 and (0.8-35.6) × 10 -5 s -1 , respectively. Quantitative estimates of the influence of precipitation parameters (amount, intensity and duration) on the daily total 7 Be wet deposition flux, mean 7 Be activity concentration in precipitation, washout ratio, deposition velocity and scavenging coefficient with individual precipitation events have been obtained using correlation analysis. It has been found that precipitation amount has the greatest influence on 7 Be deposition flux and deposition velocity, precipitation intensity has the greatest influence on washout ratio and scavenging coefficient, and precipitation duration has the greatest influence on 7 Be activity concentration in precipitation. The relationships between these parameters have been parameterized. Based on these parameterizations, five 1D models that calculate the daily total 7 Be wet deposition flux have been introduced and validated against the observation data. It has been revealed that the model, which is based on deposition velocity parameterization and uses the data on 7 Be activity concentration in the atmosphere and the daily amount of precipitation as predictors, reproduces the highest fraction of the observational data (88%) with the lowest average calculation error (32%) compared to the other four models., Competing Interests: Declaration of competing interest The authors 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 © 2022 Elsevier Ltd. All rights reserved.)

A miniature luminol chemiluminescence system based on atmosphere microplasma is proposed for detection without any catalysts. In our research, atmosphere microplasma jet is employed to oxidize luminol and produce chemiluminescence instead of H 2 O 2 . The transport of OH radicals to the plasma-liquid interface and induce the chemiluminescence. The weight of the system is only 3.6 kg (including a 1.2 kg laptop), and the power consumption of the microplasma is only 0.045 W. The mechanism of luminol chemiluminiscence induced by microplasma jet and generation of microplasma jet are investigated in this study. A 1 mL sample solution is sufficient for trace 3-NPA determination within an analysis time of 6 min. In the range of 0.03-10 mg L -1 , 3-NPA can be quantitatively analyzed along with a detection limit of 0.008 mg L -1 . In addition, the proposed system is employed for real-world samples detection, including water samples, brown sugar and tainted sugarcane, which demonstrates the reliability and practical feasibility of the detection method., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The vertical distribution of the tropospheric ozone column concentration (OCC) in China from 2005 to 2020 was analysed based on the ozone profile product of the ozone monitoring instrument (OMI). The annual average OCC in the lower troposphere (OCC LT ) showed an increasing trend, with an average annual increase of 0.143 DU. The OCC in the middle troposphere showed a downward trend, with an average annual decrease of 0.091 DU. There was a significant negative correlation between the ozone changes in the two layers. The monthly average results show that the peak values of OCC LT occur in May or June, the middle troposphere is significantly influenced by topographic conditions, and the upper troposphere is mainly affected by latitude. Analysis based on multi-source data shows that the reduction in nitrogen oxides (NO x ) and the increase in volatile organic compounds (VOCs) weakened the titration of ozone generation, resulting in the increase in OCC LT . The increase in vegetation is closely related to the increase in OCC LT , with a correlation coefficient of up to 0.875. The near-surface temperature increased significantly, which strengthened the photochemical reaction of ozone. In addition, the increase in boundary layer height also plays a positive role in the increase in OCC LT .

With the intensification of human activities, the mixture of anthropogenic pollutants and natural dust aerosols in the vicinity of the Taklimakan Desert (TD) has become a new uncertainty in the weather and climate system. In this study, using a Weather Research and Forecasting model version 4.0 with the Thompson aerosol-aware microphysics scheme, we investigated the impact of anthropogenic aerosols on clouds and precipitation in an atmospheric environment with abundant dust aerosols in the vicinity of the TD. Our findings indicate that anthropogenic aerosols can increase cloud droplet number concentrations in the vicinity of the TD, and the maximum percentage increase can reach 50 %. In addition, the effective radius of water clouds decreases significantly due to anthropogenic aerosols, which means that more numerous but smaller cloud droplets are formed with enhanced anthropogenic aerosol loading under a dusty background. Meanwhile, anthropogenic aerosols can decrease raindrops below 650 hPa, graupel and snow particles, causing less precipitation in the dusty atmosphere surrounding the TD. Furthermore, the anthropogenic aerosol-induced changes in daily precipitation accumulation are also large, with a regionally averaged maximum reduction of up to 4.2 %. Therefore, anthropogenic aerosols are an important factor that exacerbates aridity in the vicinity of the TD, and there is an urgent need to control anthropogenic pollutants around the TD., Competing Interests: Declaration of competing interest No conflict of interest exits in the submission of this manuscript, and manuscript is approved by all authors for publication., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Various global change factors (e.g. elevated CO 2 concentrations, nitrogen deposition, etc.) can alter the amount of litterfall in terrestrial forests, which could subsequently lead to changes in the physical, chemical, and biological properties of forest soils. Yet, there is hitherto a lack of consensus on the role of litter in governing the soil-atmosphere exchange of greenhouse gases (GHGs) in forest ecosystems, which can significantly affect the overall climatic cooling impacts of forests as a net carbon sink. In this study, we carried out a meta-analysis of over 250 field observations to determine the response of soil GHG fluxes to in situ litter manipulation in global forests. Our results showed that overall, litter addition enhanced soil CO 2 emissions from terrestrial forests by 26%, while litter removal reduced soil CO 2 emissions from these forests by 26%. The negative response of soil CO 2 emissions to litter removal was stronger in the tropical forests (-33%) than in the subtropical (-27%) and temperate (-21%) forests, and was significantly correlated with mean annual temperature and precipitation. Moreover, litter removal was observed to enhance soil CH 4 uptake in tropical (+24%) and temperate (+9%) forests, but not in subtropical forests. Litter removal reduced N 2 O emissions from forest soils by 20% on average, with this negative effect increasing with mean annual precipitation. The duration of litter removal experiment was negatively correlated with the response of soil CO 2 emissions but had no influence on the response of soil CH 4 and N 2 O fluxes. We found that plant litter supply could alter soil GHG fluxes in forests by modulating the microclimate as well as the labile and recalcitrant soil carbon pools. Our findings highlighted the importance of considering the effects of changing plant litter inputs on soil-atmosphere GHG fluxes in terrestrial forests and their spatio-temporal variability in biogeochemical models., Competing Interests: Declaration of competing interest The authors 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 © 2022 Elsevier B.V. All rights reserved.)

Atmospheric oxidation is a driving force of complex air pollution, and accurate hydroxyl radical (OH) measurement is helpful in investigating the radical-cored photooxidation mechanism in the troposphere. A self-developed laser-induced fluorescence instrument by the Anhui Institute of Optics Fine Mechanics, Chinese Academy of Sciences (AIOFM-LIF), was able to measure OH concentration with high sensitivity and good time resolution, and a detection limit of 1.7 × 10 5 cm -3 (1σ, 30 s). A long-period, multi-level intercomparison of hydroxyl radical (OH) measurements between AIOFM-LIF and PKU-LIF (the Peking University laser-induced fluorescence system) was conducted in Chengdu, China. The measurement between two instruments was in excellent agreement in the 5-min time resolution. Linear regression analysis reported a linear slope of 0.96 with a 0.68 × 10 6 cm -3 offset, and the correlation coefficient R 2 was 0.85. The overall linearity with only a slight offset indicated a negligible influence on OH measurement. No noticeable artifacts from ozonolysis were observed under the condition of high ozone and ozonolysis-related compound concentrations. In addition to the subtraction of background signal through wavelength modulation, the dynamic correction on ozone photolysis interference ensured high intercomparison quality in both relatively constant and rapidly varying periods. Based on the reliability of OH AIOFM and OH PKU , comparisons under different oxidation-related species (NOx, VOCs, O 3 , PM 2.5 ) levels and typical scenarios (rich-BVOC and high-reactivity) were carried out to evaluate the performance under complex atmospheres. A slightly higher drift was observed in a certain scenario, but the general data variability due to environmental changes did not affect the measurement accuracy. The intercomparison demonstrated that both systems are able to achieve reliable OH data under typical conditions of complex atmospheric pollution in China. Additional improvements are necessary for future intercomparisons in order to enhance the confidence in OH detection accuracy., Competing Interests: Declaration of Competing Interest The authors 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 © 2022 Elsevier B.V. All rights reserved.)

The focus of this study is to evaluate the influence of intertropical discontinuity (ITD) on the variation of total column ozone (TCO). Relevant information is supplied on the temporal and spatial variability of TCO along the ITD zone, which is an important factor influencing the earth's atmosphere. Several studies over the years have established the relationship and have influence several atmospheric processes on TCO. However, the relationship between intertropical discontinuity and TCO over West Africa has a gap. This study tends to examine the influence ITD has on TCO variation using the West African region as a case study. The study used wind, ozone, and dewpoint temperature data for the period between 1980 and 2019. To assess the variability and trend over the study region, several statistical methods were used, including Pearson correlation, Mann-Kendall, and linear regression model. The Mann-Kendall test shows an increasing trend throughout the months over the study region. Spatial analysis also revealed that regions north of the ITD have a higher concentration of TCO than the southern region of the ITD between April and September. However, ITD influence was more visible during the wet months of June to August (JJA) as the highest concentration of TCO was observed during this period across all latitude, but more deviation was observed between latitude 10 to 18° N, while the least occurrence is observed when ITD is at its minimum position in the month of December to February (DJF). The ACRV shows that 14° N exhibit the highest variation with a value of 4.84, while the deviation is also at its highest with value of 13.65. The monthly position of ITD for 40 years was also analysed to observe the monthly deviation along the ITD region 40 years, and the spatial distribution of TCO was analysed from January to December. It is of note that during the cause of this study, low-ozone values of 220DU are not found in the study region. The highest and the lowest value of TCO is 295 DU and 227 DU, respectively, with an average range of 68DU., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Fatty acids have been proposed to be a potential source of precursors for SOAs, but the autoxidation process was neglected in the oxidation studies. Here, the autoxidation of oleic acid was explored using microdroplet mass spectrometry. Bulk solution, concentration and solvent composition experiments provided direct evidences for that the autoxidation occurred at or near the air-water interface. The kinetic data showed an acceleration at this interface and was comparable to ozonation, indicating that autoxidation is an important pathway for SOAs formation. In addition, intermediates/products were captured and identified using tandem mass spectrometry, spin-trapping and quenched agents. The autoxidation mechanism was divided into addition intermediates (AIs) and Criegee intermediates (CIs) pathways mediated by hydroxyl radicals (OH). The CI chemistry which is ubiquitous in gas phase was observed at the air-water interface, and this leaded to the mass/volume loss of aerosols. Inversely, the AI chemistry caused the increase of mass, density and hygroscopicity of aerosols. AI chemistry was dominated compared to CI chemistry, but varied by concerning aerosol sizes, ultraviolet light (UV) and charge. Moreover, the MS approach of selectively probing the interfacial substances at the scale of sub-seconds opens new opportunities to study heterogeneous chemistry in atmosphere., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Global mean lower stratosphere temperatures rose abruptly in January 2020 reaching values not experienced since the early 1990s. Anomalously high lower stratospheric temperatures were recorded for 4 months at highly statistically significant levels. Here, we use a combination of satellite and surface-based remote sensing observations to derive a time-series of stratospheric biomass burning aerosol optical depths originating from intense SouthEastern Australian wildfires and use these aerosol optical depths in a state-of-the-art climate model. We show that the S.E. Australian wildfires are the cause of this lower stratospheric warming. We also investigate the radiatively-driven dynamical response to the observed stratospheric ozone perturbation and find a significant strengthening of the springtime Antarctic polar vortex suggesting that biomass burning aerosols play a significant role in the observed anomalous longevity of the ozone hole in 2020., (© 2022. The Author(s).)

Mercury (Hg) stable isotope analysis has become a powerful tool to identify Hg sources and to understand its biogeochemical processes. However, it is challenging to link the observed Hg isotope fractionation to its global cycling. Here, we integrate source Hg isotope signatures and process-based Hg isotope fractionation into a three-dimensional isotope model based on the GEOS-Chem model platform. Our simulated isotope compositions of total gaseous Hg (TGM) are broadly comparable with available observations across global regions. The isotope compositions of global TGM, potentially distinguishable over different regions, are caused by the atmospheric mixture of anthropogenic, natural, and re-emitted Hg sources, superimposed with competing processes, notably gaseous Hg(0) dry deposition and Hg redox transformations. We find that Hg(0) dry deposition has a great impact on the isotope compositions of global TGM and drives the seasonal variation of δ 202 Hg in forest-covered regions. The atmospheric photo-reduction of Hg(Ⅱ) dominates over Hg(0) oxidation in driving the global Δ 199 Hg (and Δ 201 Hg) distribution patterns in TGM. We suggest that the magnitude of isotope fractionation associated with atmospheric aqueous-phase Hg(Ⅱ) reduction is likely close to aquatic Hg(Ⅱ) reduction. Our model provides a vital tool for coupling the global atmospheric Hg cycle and its isotope fractionation at various scales and advances our understanding of atmospheric Hg transfer and transformation mechanisms., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Atmospheric lead (Pb) pollution has attracted long-term and widespread concerns due to its high toxicity. The definite source identification of atmospheric Pb is the key step to mitigate this pollution. Here, we first report an overlooked source of atmospheric nanosized Pb particles using transmission electron microscopy and bulk sample analyses, finding that residential honeycomb briquette combustion emits large numbers of nanosized Pb-rich particles. We found that 33.7 ± 19.9 % of primary particles by number from residential honeycomb briquette combustion contains the crystalline Pb particles. These Pb-rich particles range in size from 14 to 956 nm with a mean diameter of 117 nm. Compared with raw coal chunks, honeycomb briquette combustion could emit less carbonaceous particles, but largely increase nanosized Pb particle emissions. This result is attributed to two key factors: (1) higher Pb content in honeycomb briquette (63.6 μg g -1 ) than that in coal chunk (8.5 μg g -1 ), and (2) higher Pb release rate for honeycomb briquette (62.3 %) caused by honeycomb structure than that for coal chunk (20.1 %). This study highlights that atmospheric and health implications of high emissions of toxic nanosized Pb from honeycomb briquette should be paid more attention in future research on ambient and indoor airs., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Numerous studies found the presence of persistent organic pollutants (POPs) in various environmental compartments, including air, water, and soil. POPs have been discovered in various industrial and agricultural products with severe environmental and human health consequences. According to the data, South Korea is a hotspot for POP pollution in the southern part of Asia; hence, South Korea has implemented the Stockholm Convention's National Implementation Plan (NIP) to address this worldwide issue. The purpose of this review is to assess the distribution pattern of POPs pollution in South Korea's atmosphere. According to findings, PAHs, PCBs, BFRs, and PBDEs significantly polluted the atmosphere of South Korea; however, assessing their exposure nationwide is difficult due to a shortage of data. The POPs temporal trend and meta-analysis disclosed no proof of a decrease in PAHs and BFRs residues in the atmosphere. However, POP pollution in South Korea tends to decrease compared to contamination levels in neighboring countries like Japan and China., (Copyright © 2022 Elsevier Ltd. All rights reserved.)