Range Transport Research Articles

Source Assessment of PM-2.5 in the Residential Areas of Gwangyang Bay using Source Apportionment Model(II)

The source contributions in PM-2.5 were investigated in two residential areas (i.e., Yeosu and Suncheon of Gwangyang Bay) using a source apportionment model. As a result, eight sources have been identified such as secondary sulfate (31%), mobile (16.8%), secondary nitrate (15.9%), soil and road emission (15.2%), biomass burning (11.5%), oil combustion (4.2%), coal combustion (3.7%), and industry activity (1.7%) in the Yeosu area. In the Suncheon area, secondary sulfate (27.3%), biomass burning (16.4%), and secondary nitrate (15.3%) were investigated as the major sources. Clustering of the trajectories revealed dominant wind patterns associated with high concentrations due to long range transport. In conclusion, this study shows that the source apportionment model yields results for identifying pollutant sources in two receptor locations.

Enhancement in free-tropospheric aerosol loading over India

Free-tropospheric aerosol loading and its changes assume importance as the diabatic heating due to radiation absorption by aerosols is more intense at higher altitudes. The present study quantifies trends in free-tropospheric aerosol loading over Indian landmass and examines the role of local production and long range transport, using multi-satellite observations and reanalysis data. Increasing trends in free-tropospheric aerosol abundance are seen over most of the regions in almost all the seasons. Strongest positive trend over the Indian landmass is seen in post-monsoon, with mean rate of increase in free-tropospheric aerosol optical depth (AODFree Troposphere) 0.063dec−1. While dust aerosol loading in the free-troposphere decreases, smoke aerosol concentration increases over the Indian landmass. While increase in columnar and free-tropospheric aerosol loading is seen over larger regions of the Indian landmass, including regions of northwest India, Indo Gangetic Plain (IGP), central India and southern peninsula, enhancement in aerosol production is observed mainly over the regions of northwest India in post-monsoon. Due to the prevailing westerly winds, aerosols over northwest India are transported through IGP to its central and eastern regions. Increase in aerosol production over northwest India and strengthening of updrafts over the central and eastern IGP lead to vertical uplift of more aerosols into the free-tropospheric altitudes. These free-tropospheric aerosols are subsequently transported, by the prevailing anti-cyclonic system, to the regions of central India and southern peninsula and cause the enhancement in free-tropospheric aerosol loading over these regions in post-monsoon. Though strengthening of updraft is observed over the regions of central India and southern Peninsula, net aerosol production is not seen to be increasing over these regions. The observed enhancement in free-tropospheric aerosols over Indian landmass is important as they can affect the thermal structure and stability of the atmosphere and modify the properties and distribution of clouds.

Interfacility Transport of Mechanically Ventilated Patients with Suspected COVID-19 in the Prone Position

Objective Prone positioning during mechanical ventilation in patients with severe respiratory failure is an important intervention with both physiologic and empiric rationale for its use. This study describes a consecutive cohort of patients with severe hypoxemic respiratory failure due to COVID-19 who were transported in the prone position in order to determine the incidence of serious adverse events (SAEs) during transport. Methods This retrospective study used prospectively collected data from a provincial air and land critical care transport system where specially trained critical care paramedic crews transported intubated and mechanically ventilated patients with COVID-19 in the prone position. SAEs were determined a priori, and included markers of new hemodynamic or respiratory instability, new resuscitative measures, and equipment or vehicle malfunction. Two authors independently reviewed each patient care record to identify SAEs during transport, and the ability of the crews to successfully manage such events. Results From April 2020 to June 2021, 127 intubated and mechanically ventilated patients were transported in the prone position. Of these, 117 were transported by land vehicle, 7 by rotor-wing, and 3 by fixed wing aircraft. 67 (52.8%) were vasopressor-dependent, 5 (3.9%) were receiving inhaled vasodilators, 9 (7.1%) were hypoxic (SpO2 < 88%), and 3 (2.4%) were hypotensive (SBP < 90 or MAP < 65 mm Hg) when the transport crew made patient contact at the sending hospital. Of the 122 (96.1%) patients in which a pre-transport PaO2/FiO2 ratio was available, the mean (median; range) was 86.7 (81; 47–144), with 27 patients greater having a ratio greater than 100. The mean (median; range) transport time was 49 (45; 14–176) minutes. There were 19 SAEs in 18 (14.2%) patients during transport, the most common of which was new hypoxia requiring ventilator adjustments (15 of 18 patients). All SAEs were successfully managed by the transport crews. No patient experienced tracheal tube obstruction, unintentional extubation, cardiac arrest, or died during transport. Conclusion Patients with severe hypoxemic respiratory failure due to COVID-19 can be safely transported in the prone position by specially trained critical care paramedic crews.

PM2.5 in Sri Lanka: Trend Analysis, Low-cost Sensor Correlations and Spatial Distribution

The South Asian island nation of Sri Lanka did not have any permanent PM2.5 monitors sharing data publicly in near-real-time until the U.S. Embassy installed a Beta Attenuation Monitor (BAM) in September 2017. This research aims to better understand the PM2.5 distribution in Sri Lanka by analyzing data collected by that BAM, and leveraging low-cost sensors, model and remote sensing data. BAM data show PM2.5 levels were “Unhealthy for Sensitive Groups” or “Unhealthy” according to the U.S. classification system, for at least 50% of the time between each November and the following February. This coincides with the northeast monsoon when stable air masses reduce dispersion of pollutants. Back trajectory analyses suggest long range transport also contributes to elevated PM2.5 during these months. Although slightly cleaner than regional embassies, this location has exceeded the Sri Lankan 24-hr standard for PM2.5 (50 µg m–3) every year since 2018. The area has met Sri Lanka’s annual standard (25 µg m–3) since 2019. We used PurpleAir (PA) and Atmos low-cost PM2.5 sensors co-located with the Embassy BAM, to develop correction factors to transform raw sensor data to BAM-like data. The influence of meteorological variables and the performance of different statistical models were considered and the regression coefficients of the most applicable models are presented. We also compared our PA correction factor against user-selectable options on the PurpleAir.com website. The Australian “Woodsmoke” correction can be applied to quickly visualize a reasonably accurate estimate of PM2.5 concentrations. We applied our PA correction factor to six other PurpleAir sensors operated around the country, to understand Sri Lanka’s PM2.5 distribution. With these corrected data, we interpolated satellite and model-derived PM2.5 annual averages at 1 km intervals. The most populated Western Province had the highest concentrations with elevated levels extending offshore. The sparsely populated southeast had the cleanest air.

Long Range Transport of Atmospheric Microplastics Deposited Onto Glacier in Southeast Tibetan Plateau

Long Range Transport of Atmospheric Microplastics Deposited Onto Glacier in Southeast Tibetan Plateau

Influence of south Asian outflow on secondary organic aerosol formation over the Indian Ocean: Inferences from water-soluble low molecular weight dicarboxylic acids and related organic compounds during ICARB 2018 experiment

Low molecular weight dicarboxylic acids constituting a pivotal fraction of organic aerosols impact radiative forcing of Earth's atmosphere. However, a significant knowledge gap exists associated with their sources and formation pathways in the atmosphere. In this study, we report on water-soluble components such as dicarboxylic acids, oxoacids, and α-dicarbonyls as well as carbonaceous and ionic components in the continental outflow from the South Asian region to the Arabian Sea and the equatorial Indian Ocean during ICARB (Integrated Campaign for Aerosols, gases and Radiation Budget) 2018 experiment. Non-sea-salt sulfate (nss SO42−) was found to be the predominant component, followed by ammonium (NH4+) and organic carbon (OC) in fine-sized (<1.1 μm) aerosols. Total diacids carbon content accounted for 17% (on average) of total carbon (TC). Oxalic acid (C2) was the most abundant organic acid, contributing ~41% to total diacids, followed by terephthalic acid (tPh) and succinic acid (C4). Of these results, together with selected organic and inorganic mass ratios and linear relationships among the organic acids, we highlight the sources of organic acids over Indian Ocean. Over continental outflow regions in Indian Ocean, dicarboxylic acids are majorly derived from the emissions of biomass burning and combustion related sources, that underwent transformation in the atmosphere through photochemical reactions during the long range transport. However, over the deep oceanic environment of Indian Ocean, photo-oxidation of biogenic unsaturated fatty acids were found to be the important sources. The findings from this study will be helpful to improve further our understanding of the sources and formation processes of organic aerosols and their climate effects over the South Asian outflow regions.

Determination of 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanone (NNK) arising from tobacco smoke in airborne particulate matter

The most important tobacco-specific nitrosamine found in cigarette smoke and formed in ageing smoke after cigarettes are extinguished is 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). It is formed from nitrosation of nicotine, under particular conditions both in indoor and outdoor environments. NNK has been classified as a potent lung carcinogen which is expected to be found primarily in the particle-phase and to be stable in particulate matter. In this study tests have been carried out to show that a bisulfate-treated filter is more efficient than an untreated filter to collect both nicotine and NNK, and that the latter is stable in outdoor particulate matter. To characterize NNK in the outdoor environment, airborne samples were collected from 11 cities in USA, UK, Hong Kong and Malta with characteristics varying from low to high population densities and from urban to suburban to rural, and with desert characteristics and distinct climates. It has been shown that airborne particle + gas phase nicotine and particle-phase NNK behave in a linearly correlated manner. A seasonal analysis was carried out on a subset of data available from five sites in California, where the load of NNK in PM10 is driven by long range transport of the air masses passing over densely populated cities. In the winter season, the load of NNK in PM is higher than in summer in a statistically significant manner. The contamination of PM with NNK shows variability, but is observed at all sites. This paper highlights the potential risk of chronic exposure to NNK in particulate matter by the inhalation pathway.

Charge transport variation from Bloch\u2013Gr\xfcneisen to Mott variable range hopping and transport change due to hydrogenation in Palladium thin films

We report a systematic investigation of the differences in charge transport mechanism in ultra-thin nano-island like films of palladium with thickness varying between 5 nm and 3 nm. The thicker films were found to be metallic in a large temperature range with a dominant Bloch–Grüneisen mechanism of charge transport arising due to electron-acoustic phonon scattering. These films were also found to exhibit an additional electron–magnon scattering. At temperatures below 20 K, the two films displayed a metal-insulator transition which was explained using Al’tshuler’s model of increased scattering in disordered conductors. The thinner films were insulating and were found to exhibit Mott’s variable range hopping mechanism of charge transport. The thinnest film showed a linear decrease of resistance with an increase in temperature in the entire temperature range. The island-like thin films were found to display very different response to hydrogenation at room temperature where the metallic films were found to display a decrease of resistance while the insulating films were found to have an increase of resistance. The decrease of resistance was ascribed to a hydrogen induced lattice expansion in the thin films that were at the percolation threshold while the resistance increase to an increase in work function of the films due to an increased adsorption of the hydrogen atoms at the surface sites of palladium.

Bioactive Natural Products in Actinobacteria Isolated in Rainwater From Storm Clouds Transported by Western Winds in Spain.

Actinobacteria are the main producers of bioactive natural products essential for human health. Although their diversity in the atmosphere remains largely unexplored, using a multidisciplinary approach, we studied here 27 antibiotic producing Actinobacteria strains, isolated from 13 different precipitation events at three locations in Northern and Southern Spain. Rain samples were collected throughout 2013–2016, from events with prevailing Western winds. NOAA HYSPLIT meteorological analyses were used to estimate the sources and trajectories of the air-mass that caused the rainfall events. Five-day backward air masses trajectories of the diverse events reveals a main oceanic source from the North Atlantic Ocean, and in some events long range transport from the Pacific and the Arctic Oceans; terrestrial sources from continental North America and Western Europe were also estimated. Different strains were isolated depending on the precipitation event and the latitude of the sampling site. Taxonomic identification by 16S rRNA sequencing and phylogenetic analysis revealed these strains to belong to two Actinobacteria genera. Most of the isolates belong to the genus Streptomyces, thus increasing the number of species of this genus isolated from the atmosphere. Furthermore, five strains belonging to the rare Actinobacterial genus Nocardiopsis were isolated in some events. These results reinforce our previous Streptomyces atmospheric dispersion model, which we extend herein to the genus Nocardiopsis. Production of bioactive secondary metabolites was analyzed by LC-UV-MS. Comparative analyses of Streptomyces and Nocardiopsis metabolites with natural product databases led to the identification of multiple, chemically diverse, compounds. Among bioactive natural products identified 55% are antibiotics, both antibacterial and antifungal, and 23% have antitumor or cytotoxic properties; also compounds with antiparasitic, anti-inflammatory, immunosuppressive, antiviral, insecticidal, neuroprotective, anti-arthritic activities were found. Our findings suggest that over time, through samples collected from different precipitation events, and space, in different sampling places, we can have access to a great diversity of Actinobacteria producing an extraordinary reservoir of bioactive natural products, from remote and very distant origins, thus highlighting the atmosphere as a contrasted source for the discovery of novel compounds of relevance in medicine and biotechnology.

The influence of wind speed on incidence of the planet population in the context of the COVID-19 pandemic

The pandemic COVID-19 continues to take dozens of human lives and destabilize the economy on the planet. In this regard study of the patterns of external conditions influence on incidence dynamics will stay relevant for a long time. In the article there are results of the study of nature and severity of impact of wind speed on COVID-19 incidence level on different continents. The analysis has made it possible to set that the wind speed has a big impact on COVID-19 incidence among population. This impact is closely related to the contamination level on the territory. With good air quality the increasing of wind speed is generally followed by increasing of the level of incidence due to SARS-CoV-2 long range transport. With satisfying or bad air quality the increasing of wind speed translates into reducing the incidence level due to the contaminants deconcentration. The main SARS-CoV-2 infection vectors are solids. Moreover, the influence of PM 2.5 is particularly harmful for human general health and immune system. Research results lead to a better understanding of physical meaning of wind speed influence on COVID-19 incidence and give an opportunity to predict the periods of the most dangerous infection conditions.

A Physics-Based Multidisciplinary Approach for the Preliminary Design and Performance Analysis of a Medium Range Aircraft with Box-Wing Architecture

The introduction of disruptive innovations in the transport aviation sector is becoming increasingly necessary. This is because there are many very demanding challenges that the transport aviation system will have to face in the years ahead. In particular, the reduction in pollutant emissions from air transport, and its impact on climate change, clearly must be addressed; moreover, sustainable solutions must be found to meet the constantly increasing demand for air traffic, and to reduce the problem of airport saturation at the same time. These three objectives seem to be in strong contrast with each other; in this paper, the introduction of a disruptive airframe configuration, called PrandtlPlane and based on a box-wing lifting system, is proposed as a solution to face these three challenges. This configuration is a more aerodynamically efficient alternative candidate to conventional aircraft, introducing benefits in terms of fuel consumption and providing the possibility to increase the payload without enlarging the overall aircraft wingspan. The development and analysis of this configuration, applied to a short-to-medium range transport aircraft, is carried out through a multi-fidelity physics-based approach. In particular, following an extensive design activity, the aerodynamic performance in different operating conditions is investigated in detail, the structural behaviour of the lifting system is assessed, and the operating missions of the aircraft are simulated. The same analysis methodologies are used to evaluate the performance of a benchmark aircraft with conventional architecture, with the aim of making direct comparisons with the box-wing aircraft and quantifying the performance differences between the two configurations. Namely, the CeRAS CSR-01, an open-access virtual representation of an A320-like aircraft, is selected as the conventional benchmark. Following such a comparative approach, the paper provides an assessment of the potential benefits of box-wing aircraft in terms of fuel consumption reduction and increase in payload capability. In particular, an increase in payload capability of 66% and a reduction in block fuel per pax km up to 22% is achieved for the PrandtlPlane with respect to the conventional benchmark, while maintaining the same maximum wingspan.

Impacts of secondary aerosol formation and long range transport on severe haze during the winter of 2017 in the Seoul metropolitan area

Severe haze episodes occur frequently in the Seoul Metropolitan Area (SMA) and throughout East Asian countries, especially during the winter and early spring. We investigated the sources and chemistry of particulate matter (PM) during three winter haze episodes in Seoul that occurred between January 1st and February 10th in 2017 using a high resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and positive matrix factorization (PMF) analysis.The average concentration of sub-micrometer aerosol (PM1 = NR-PM1 + black carbon (BC)) was 32.6 μg/m3, which was composed of 42% organics, 27% nitrate, 11% sulfate, 13% ammonium and 4% BC by mass. Six distinct sources of organic aerosol (OA) were identified: vehicle emitted hydrocarbon-like OA (HOA), cooking OA (COA), biomass burning OA (BBOA), and 3 different types of secondary OA (SOA) with varying degrees of oxidation and temporal trends.The nitrate mass fraction increased during the three haze episodes, with nitrate accounting for 27-33% of PM1 mass. Enhanced nitrate concentrations and higher nitrate oxidation ratios (NOR), despite lower enhancement in relative humidity (RH) than the low PM loading period, suggest that regional transport of nitrate contributed to the nitrate mass during the haze periods.Lower HOA and COA concentrations during the high PM loading periods further confirm that local emissions or stagnant meteorological conditions were not the main reason for the severe haze. Residence time analysis (RTA), concentration field analysis (CFA), and column-CFA results from FLEXPART also showed that the measurement period was accompanied by atmospheric transport of nitrate, sulfate, and ammonium from eastern China. Nevertheless, we found that NO2, a precursor of nitrate, was predominantly from local emissions. These findings suggest that nitrate in Seoul is not only locally formed, but also transported from upwind areas.

818Prediction of health effects of Asian dust using the MASINGAR in Japan

Abstract Background Health effects of cross-border air pollutants and Asian dust are of significant concern in Japan. Currently, models predicting arrival of aerosols have not investigated the association between arrival predictions and health effects. We investigated the association between subjective health symptoms and data acquired from the Japan Meteorological Agency's (JMA's) the Model of Aerosol Species in the Global Atmosphere (MASINGAR) aerosol model with the objective of ascertaining if the data could be applied for predicting health effects. Methods Subjective symptom scores were collected using self-administered questionnaires and used with JMA model’s surface concentration data to conduct a risk evaluation using multiple linear mixed model, during 2013 to 2015. Altogether, 160 individuals provided 16226 responses. Data regarding climate (temperature, humidity, and atmospheric pressure) and environmental factors (NO2, SO2 and Ox) were used as covariates. We calculated the association between the surface dust concentration and symptoms. Results A strong association was also observed for nasal and cough symptoms (P for trend &amp;lt; 0.001). The differences in scores of nasal symptoms (sneezing and runny) of the highest quartile [Q4] vs. the lowest [Q1] were 0.039 (95% confidence interval (CI): 0.02–0.01, p &amp;lt; 0.05) and 0.046 (95% CI: 0.002–0.02, p &amp;lt; 0.05), respectively. The differences in scores of cough symptoms were 0.036 (95% confidence interval (CI): 0.002–0.01, p &amp;lt; 0.05). Conclusions This study suggests that predictive models for pollutants’ arrival can be used to capability to foresee and possibly prevent the health impact of long range transport of air pollutants, recommending the potential role of aerosol forecast models in health care. MASINGAR is Global Spectral Model (GSM), this have the potential that can contribute in health predictions all over the world. Key messages Asian dust, Health forecast, Allergic symptom

Assessment of Low-Cost Particulate Matter Sensor Systems against Optical and Gravimetric Methods in a Field Co-Location in Norway

The increased availability of commercially-available low-cost air quality sensors combined with increased interest in their use by citizen scientists, community groups, and professionals is resulting in rapid adoption, despite data quality concerns. We have characterized three out-the-box PM sensor systems under different environmental conditions, using field colocation against reference equipment. The sensor systems integrate Plantower 5003, Sensirion SPS30 and Alphasense OCP-N3 PM sensors. The first two use photometry as a measuring technique, while the third one is an optical particle counter. For the performance evaluation, we co-located 3 units of each manufacturer and compared the results against optical (FIDAS) and gravimetric (KFG) methods for a period of 7 weeks (28 August to 19 October 2020). During the period from 2nd and 5th October, unusually high PM concentrations were observed due to a long-range transport episode. The results show that the highest correlations between the sensor systems and the optical reference are observed for PM1, with coefficients of determination above 0.9, followed by PM2.5. All the sensor units struggle to correctly measure PM10, and the coefficients of determination vary between 0.45 and 0.64. This behavior is also corroborated when using the gravimetric method, where correlations are significantly higher for PM2.5 than for PM10, especially for the sensor systems based on photometry. During the long range transport event the performance of the photometric sensors was heavily affected, and PM10 was largely underestimated. The sensor systems evaluated in this study had good agreement with the reference instrumentation for PM1 and PM2.5; however, they struggled to correctly measure PM10. The sensors also showed a decrease in accuracy when the ambient size distribution was different from the one for which the manufacturer had calibrated the sensor, and during weather conditions with high relative humidity. When interpreting and communicating air quality data measured using low-cost sensor systems, it is important to consider such limitations in order not to risk misinterpretation of the resulting data.

Insights into sources and occurrence of oxy- and nitro-PAHs in the alberta oil sands region using a network of passive air samplers

Mining-related activities in the Alberta Oil Sands Region (AOSR) are known to emit polycyclic aromatic hydrocarbons (PAHs) and related compounds to ambient air. This is a concern due to the toxicity of PAHs, including their transformation products such as nitrated (NPAHs) and oxygenated (OPAHs) PAHs. This is the first study that provided a more extensive outlook into the sources, occurrence in air, and spatial and seasonal patterns of NPAHs and OPAHs in the AOSR by using passive air sampling. A sampling campaign from 2013 to 2016 revealed concentrations of NPAHs that were much lower than those of OPAHs. The highest concentrations of NPAHs were concentrated in the region associated with extensive mining activities, with ∑NPAH concentrations ranging from 20 to 250 pg/m3. Within the oil sands (OS) mineable area, NPAHs associated with primary release appear more commonly, while NPAHs produced via oxidative transformation are predominant outside of this area. The concentrations of ∑OPAH ranged from 400 to 2400 pg/m3, with the highest air concentrations in the region located south of the main OS activity zone, with peak concentrations attributed to a 2016 forest fire event. Uptake of PAHs from ambient air and their subsequent conversion to generate OPAHs is believed to play an important role in wildfire emissions of OPAHs. The seasonal trend investigation was inconclusive, with NPAHs slightly higher during the winter, while OPAHs were slightly elevated during summer. A preliminary comparison of ambient concentrations of OPAHs and NPAHs in the AOSR to measurements in the Greater Toronto Area revealed a similar range of concentrations, but also a unique presence of certain NPAHs such as 4-nitrobiphenyl, 2-nitrodibenzothiophene, 2,8-dinitrodibenzothiophene and 6-nitrobenzo-(a)-pyrene. This indicates that AOSR might have its own NPAH profile – creating the need to better understand associated NPAH toxicity and propensity for long range transport.

D–Band Contraction of Metal Nitride Nanosheets Enables Highly Efficient and Stable Electrochemical Oxidation of Ammonia

Ammonia is a promising hydrogen carrier as it reduces the cost of long–range transportation of hydrogen. Ammonia electrolysis provides a convenient method to extract hydrogen from ammonia at end users. However, the conventional platinum carbon electrode suffers from fast degradation and electrode fouling at electrode–electrolyte interface during the ammonia electrochemical oxidation(AOR). Here, we report that nitriding electrochemical deposited nickel cobalt layered double hydroxide nanosheets can achieve high electrocatalytic activity for AOR in non–aqueous solution. The AOR onset overpotential of NiCo2N nanosheets is 0.55 V which is about 0.25 V lower than that of the platinum carbon electrode. Ultraviolet–visible and Mass spectroscopy studies reveal NiCo2N nanosheets can suppress the formation of metal amine complex and preferentially oxidize ammonia to N2 with a faradic efficiency of over 90 percent. DFT calculation indicates that the downshift of the metal d–band center on NiCo2N nanosheets surface accelerated the generation of NH+ X cations and desorption of final N2*, boosting ammonia electrochemical oxidation toward N2. Overall, this work introduces a practical strategy for synthesizing an active and stable electrocatalyst for AOR.

Assessment of the relative influences of long-range transport, fossil fuel and biomass burning from aerosol pollution under restricted anthropogenic emissions: A national scenario in India

The present study was conducted with the purpose to understand the spatial heterogeneity and the inter-state variability of the relative contributions of the long-range transport, fossil fuel and biomass burning on the atmospheric aerosol pollution across India. Satellite and reanalysis datasets (MODIS and MERRA-2) were used to study the total aerosol and its differential components over each of the Indian states under the limited anthropogenic emission condition (April 2020) and compared with the normal condition (April 2015–2019). We observed that the changes in aerosol pollution with the changes in sources from normal to limited anthropogenic activities were not homogeneous across the country. Based on such heterogeneity in “aerosol source-aerosol pollution” relationship, we divided the entire country in four different groups. The states under Group 1 (most of Indo-Gangetic Plain, north-eastern and parts of western and southern India) are found to be mostly influenced by the local/regional anthropogenic sources. The sources other than the biomass burning are the most influential for the aerosol pollution over Group 2 states (Punjab, West Bengal, Rajasthan, Madhya Pradesh, Karnataka and Tripura). Both the biomass burning and long range transport are the major factors for Group 3 state, Telangana. Rest of the states (Group 4) exhibit the relative dominance of the regional and trans-boundary transport over local anthropogenic emissions. Relative influences of fossil fuel and biomass burning over each other and how it changed from the normal to limited activities have also been quantified for each of the states of different groups. The results from the study would be an input of immense importance for the policy makers building state-wise strategies in air pollution control in India.

Compound-specific radiocarbon reveals sources and land–sea transport of polycyclic aromatic hydrocarbons in an urban estuary

As typical chemical indicators of the Anthropocene, polycyclic aromatic hydrocarbons (PAHs) and their environmental behavior in urban estuaries can reveal the influence of anthropogenic activities on coastal zones worldwide. In contrast to conventional approaches based on concentration datasets, we provide a compound-specific radiocarbon (14C) perspective to quantitatively evaluate the sources and land‒sea transport of PAHs in an estuarine‒coastal surficial sedimentary system impacted by anthropogenic activities and coastal currents. Compound-specific 14C of PAHs and their 14C end-member mixing models showed that 67−73% of fluoranthene and pyrene and 76−80% of five- and six-ring PAHs in the Jiulong River Estuary (JRE, China) originated from fossil fuels (e.g., coal, oil spill, and petroleum-related emissions). In the adjacent Western Taiwan Strait (WTS), the contributions of fossil fuel to these PAH groups were higher at 74−79% and 84−87%, respectively. Furthermore, as a significant biomarker for source allocation of terrigenous organic matter, perylene, a typical five-ring PAH, and its land‒sea transport from the basin through the JRE and finally to the WTS was quantitatively evaluated based on the 14C transport models. In the JRE, fluvial erosions and anthropogenic emissions affected the 14C signature of perylene (Δ14Cperylene, -535 ± 5‰) with contributions of > 38% and < 62%, respectively. From the JRE to the WTS, the decreased Δ14Cperylene (-735 ± 4‰) could be attributed to the long‒range transport of “ocean current-driven” perylene (-919 ± 53‰) with a contribution of 53 ± 8%. This compound-specific 14C approach and PAH transport model help provide a valuable reference for accurately quantifying land‒sea transport and burial of organic pollutants in estuarine‒coastal sedimentary systems.

Size-segregated aerosols over a high altitude Himalayan and a tropical urban metropolis in Eastern India: Chemical characterization, light absorption, role of meteorology and long range transport

A study has been conducted focusing on the chemical and optical characterization of water soluble inorganic and organic components of aerosols at different sizes, over a high altitude Himalayan station, Darjeeling (27.1° N and 88.15° E, 2200 m amsl) and a tropical urban metropolis, Kolkata (22.5° N, 88.3° E, ~6 m amsl) for two-year long period (March 2016–February 2018). It was observed that local meteorology and long range transport of pollution plumes have played the pivotal role in governing the temporal variation of the mass distribution and concentration of aerosols and its various components over both the sites. The aerosol mass-size distributions were found to be bimodal in nature with the relative dominance of accumulation mode (0.1–1.0 μm) over coarse mode (1.8–10 μm) over both the stations, indicating dominance of the anthropogenic emissions. Among the size classes, accumulation mode aerosols alone contributed 55–75% over Darjeeling and 40–60% over Kolkata to PM10. The coarse mode aerosols were mainly consisted of primary inorganic species over Kolkata and water soluble organic carbons (WSOC) over Darjeeling whereas the fine mode aerosols (accumulation: 0.1–1.0 μm) were primarily composed of the secondary inorganic aerosols for both the stations. Irrespective of the seasons and stations, SO42− and NH4+ exhibited peaks in the mass-size distribution at 1.0–0.1 μm whereas that of NO3− varied with the seasons. The photochemical oxidation and the aqueous phase oxidation of SO2 (g) were the pathways for SO42− formation over Darjeeling whereas the later dominated over Kolkata. Concentration weighted trajectory (CWT) model has revealed that the secondary inorganic aerosols and WSOC were local/regional in origin over Kolkata megacity whereas Darjeeling was influenced by mixed sources. The accumulation mode aerosols were found to be the highest light absorbing over both the stations irrespective of the seasons. Over Darjeeling, the absorption coefficient (babs_365) and the mass absorption efficiency (MAE) of WSOC were maximum for local biomass burning aerosols than the transported plumes whereas those over Kolkata were maximum for transported biomass burning plumes from Eastern Ghats.

Abundance and types of plastic pollution in surface waters in the Eastern Arctic (Inuit Nunangat) and the case for reconciliation science

Plastics are not only an environmental concern but also an issue of justice in the Arctic, particularly in Inuit Nunangat (Inuit homelands), as plastics and other contaminants that originate in the south accumulate in the north and have implications for Inuit sovereignty and wellness. This collaborative study finds an average of 0.018 plastics/m2 in surface waters in two sites in the eastern Arctic (Tasiujarjuaq in Nunavut near Iqaluit and southwest Greenland offshore from Qaqortoq and Narsaq). A comparison with other studies shows this abundance of plastics is lesser than abundances reported further north in the Arctic, but greater than adjacent waters further south. However, within and across study areas at similar latitudes, there does not appear to be a significant difference in plastic abundance. Some characteristics of recovered plastics such as morphology and colour support local origins, while others support long range transport. Research moving forward should consider relative scales in spatial trends of plastic abundance. The discussion concludes by reflecting on the methods and findings in terms of their role in Inuit governance and research relationships, including elements of research personnel, permitting, categorization, measurement, and reporting findings. Our goal is to provide insights of where we, as scientists, may choose to intentionally move our scientific work towards reconciliation while we produce knowledge about environmental pollution in Inuit Nunangat and the Arctic broadly.