Emission Sources Research Articles

Touching the classical scaling in penetrative convection

The Cassini missions have identified the tiger stripes on Enceladus as the source of both thermal emission and plume jets. The hot spots in the tiger stripes are highly localized, and the plumes suggest active hydrothermal processes within the subglacial ocean of Enceladus. However, understanding the mechanism responsible for the heat anomalies in the tiger stripes remains a challenge. About 60 y ago, geoscientist George Veronis proposed a model for cold water oceans, along with the classical notion of a 1/3 scaling relationship between vertical heat transfer and the Rayleigh number (Ra), a dimensionless number representing the strength of buoyancy driving the convection within the fluid body. In this study, by delving into the steady coherent rolls arising in Veronis' model, we first confirm the existence of the classical scaling as proposed. We identify two distinct pathways, characterized by different flow patterns, that converge to the unified classical scaling. In scenarios where stratification resulting from the density's nonlinear temperature dependence is insignificant, convection rolls with fixed (width-to-height) aspect ratios achieve the classical scaling as Ra approaches infinity. Conversely, under high stratification levels, convection rolls with a heat-transport-maximizing aspect ratio achieve the classical scaling. This investigation also reveals a notable correspondence between optimal coherent rolls and turbulent flow patterns. Based on these coherent rolls, we offer insights into the formation of heat anomalies in the tiger stripes. The predicted heat flux through the ocean and the lateral flow length, are consistent with the measurements obtained by the Cassini spacecraft.

Architecting Metal-Organic Frameworks at Molecular Level toward Direct Air Capture.

Escalating carbon dioxide (CO2) emissions have intensified the greenhouse effect, posing a significant long-term threat to environmental sustainability. Direct air capture (DAC) has emerged as a promising approach to achieving a net-zero carbon future, which offers several practical advantages, such as independence from specific CO2 emission sources, economic feasibility, flexible deployment, and minimal risk of CO2 leakage. The design and optimization of DAC sorbents are crucial for accelerating industrial adoption. Metal-organic frameworks (MOFs), with high structural order and tunable pore sizes, present an ideal solution for achieving strong guest-host interactions under trace CO2 conditions. This perspective highlights recent advancements in using MOFs for DAC, examines the molecular-level effects of water vapor on trace CO2 capture, reviews data-driven computational screening methods to develop a molecularly programmable MOF platform for identifying optimal DAC sorbents, and discusses scale-up and cost of MOFs for DAC.

Proglacial methane emissions driven by meltwater and groundwater flushing in a high-Arctic glacial catchment

Abstract. Glacial groundwater is a conduit for geologic methane release in areas of glacier retreat on Svalbard, representing a large, climate-sensitive source of the greenhouse gas. Methane emissions from glacial melt rivers are known to occur in other regions of the Arctic, but such emissions have not yet been considered on Svalbard. Over the summer of 2021, we monitored methane concentrations in the proglacial groundwater springs and river network of an ∼ 20 km2 valley glacier in central Svalbard to estimate melt season emissions from a single catchment. We measured methane concentrations in the glacial river of up to 3170 nM (nearly 800 times higher than the atmospheric equilibrium concentration) and found the methane to be of thermogenic origin through isotopic analysis. We estimated a total of 1.0 t of methane emissions during the 2021 melt season from the catchment, of which nearly two-thirds are being flushed from the glacier bed by the melt river. These findings provide further evidence that terrestrial glacier forefields on Svalbard are hotspots for methane emissions, with a climate feedback loop driven by glacier melt. As the first investigation into methane emissions from glacial melt rivers on Svalbard, our study suggests that summer meltwater flushing of methane from beneath the ∼ 1400 land-terminating glaciers across Svalbard may represent an important seasonal source of emissions. Glacial melt rivers, including those from small valley glaciers, may be a growing emission point for subglacial methane across other rapidly warming regions of the Arctic.

Research of characteristics of spatial and temporal variations of CH4 emission at the water-gas interface of the Inner Mongolia section of the Yellow River and its influencing factors

ABSTRACTS It is widely recognized that rivers serve as significant sources of greenhouse gas emissions. However, the monitoring and analysis of factors influencing methane (CH4) emissions from the Yellow River remain inadequate, particularly regarding high-frequency and detailed temporal differentiation studies. This study selected six sampling points in the Inner Mongolia section of the Yellow River (IMYR) to investigate the spatio-temporal variations in CH4 flux (FCH4) and CH4 concentration (CCH4) at the water-gas interface, along with their influencing factors. The results indicate that the range of FCH4 at the gas-water interface in IMYR is −30.41 to 84.75 mg·m−2·d−1. The CCH4 in water varies from 0.07 to 0.22 μmol·L−1, indicating an overall ‘source’ effect on atmospheric CH4. Both FCH4 and CCH4 exhibit higher values in summer and lower in spring, primarily driven by temperature fluctuations. Significant spatial differentiation of FCH4 and CCH4 is observed in the Inner Mongolia section of the Yellow River, with the highest CCH4 and FCH4 values recorded in Baotou (BT) and Wuhai (WH), respectively. On a seasonal scale, dissolved oxygen (DO) and water temperature (Tw) are the primary determinants affecting CH4 emissions. Given its importance within freshwater ecosystems, greater attention should be paid to CH4 emissions from river ecosystems.

Source Contribution Analysis of Polycyclic Aromatic Hydrocarbons in PM2.5 at Three Japanese Cities Using Positive Matrix Factorization with Organic Tracers

To estimate the sources of polycyclic aromatic hydrocarbons (PAHs) and their contributions to the total PAH emissions, more than 40 PAHs and organic tracers in PM2.5 collected in 3 cities of Japan were measured and a positive matrix factorization (PMF) model analysis was performed. During the warm season, high PAH concentrations were detected in Nagoya, which is located in the port area. Total PAHs were classified into five sources: biomass combustion, semivolatile PAHs, and ship and industrial emissions, which were major, and road traffic and plastic combustion, which were minor. Analysis of the ship and industrial emissions revealed that the concentrations of these sources in the severe PAH pollution event in Nagoya exceeded 15 ng/m3 and the significant contribution exceeded 80%. In addition, PAHs indicating a risk of carcinogenicity, such as 1 to 2B by IARC and 1 to B2 by U.S. EPA, had the highest contribution to this factor among the five factors such as biomass burning and ship and industrial emissions. Our results suggest that sources of high PAH emissions exist in the port areas of Nagoya. The PMF analysis performed in this study, using combustion organics as indicators, is expected to aid other countries and regions in identifying the sources of PAHs for their effective control.

Confronting the dark matter capture rate with a continuous gravitational wave probe of local neutron stars

Continuous gravitational waves (CGWs) from various astrophysical sources are one of the many future probes of upcoming gravitational wave (GW) search missions. Neutron stars (NSs) with deformity are one of the leading sources of CGW emissions. In this work, for the first time, a novel attempt to estimate the dark matter (DM) capture rate is performed using CGW as the probe to the local NS population. Competitive bounds on DM capture from the local NS population are reported when compared with DM direct search experiments and other astrophysical observations. Published by the American Physical Society 2025

Cellular concrete: A viable low‐carbon alternative for developing countries in seismic regions?

AbstractThis study investigates the potential of cellular concrete as an environmentally friendly alternative for shear walls based structural systems in seismic‐prone areas. The construction industry significantly contributes to global energy consumption and carbon emissions, mainly through the use of conventional materials like concrete and steel. In seismic regions, the challenge is to build structures that are both sustainable and earthquake resistant. Through a “cradle‐to‐gate” life cycle assessment (LCA), the study analyses the environmental impact of constructing a seven‐story archetype residential building in Quito‐Ecuador. The research reveals that steel reinforcement is the primary source of CO2 emissions and energy consumption. Cellular concrete demonstrates a notable reduction in CO2 emissions compared with traditional concrete, emphasizing the potential of cellular concrete as a low‐carbon alternative. The findings underscore the need to integrate LCA into structural design to minimize ecological impact. While promising for developing cities, further research is essential to inform sustainable construction practices without compromising safety in seismic zones.

Volatile Organic Compounds in Early Childhood Education Facilities: Simultaneous Indoor and Outdoor Measurements in the Haifa Bay Area

Indoor air quality (IAQ) is of great importance, as people spend up to 90% of their time indoors, leading to significant exposure to air pollutants. The IAQ in early childhood education (ECE) facilities is of particular interest since young children are more vulnerable and poor air quality may have possible long-lasting impacts on them. In the present study, simultaneous indoor and outdoor VOC measurements were carried out in three ECE facilities in the Haifa Bay area, Israel. Three sampling campaigns were utilized, each lasted for a minimum of one week, encompassing four consecutive working days and at least one weekend. During working days, sampling was performed during daytime activity hours and at nighttime (off hours). Twenty-three VOCs were identified, quantified, and classified into six chemical groups—aromatic hydrocarbons, aliphatic alkanes, terpenes, alcohols, carbonyls, and “others”. The total outdoor VOC concentration was 23 μg m−3 during the daytime and 22 μg m−3 at night, with carbonyls and aromatic hydrocarbons accounting for ~80% of it. Despite the heterogeneity of the study area, outdoor concentrations depicted a smaller spatial and temporal variability than was observed indoors. In the ECE facilities, the total VOC reached 134 and 204 μg m−3 during the daytime and nighttime, respectively, and were strongly impacted by the air exchange rate. Carbonyls, alcohols, and terpenes were more prevalent indoors, accounting for 77.5–81.1% of the total. Their high indoor/outdoor ratios, especially for formaldehyde and limonene, suggest a significant contribution from indoor emission sources. Exposure calculations were compared to reference values for carcinogenic and non-carcinogenic effects. While the lifetime average daily dose (LADD) did not exceed the available reference values, the upper-limit estimates of continuous lifetime exposure to measured indoor levels indicate that formaldehyde and acetaldehyde surpassed their respective limits by factors of 10 and 3, respectively.

Small emission sources in aggregate disproportionately account for a large majority of total methane emissions from the US oil and gas sector

Abstract. Reducing methane emissions from the oil and gas (oil–gas) sector has been identified as a critically important global strategy for reducing near-term climate warming. Recent measurements, especially by satellite and aerial remote sensing, underscore the importance of targeting the small number of facilities emitting methane at high rates (i.e., “super-emitters”) for measurement and mitigation. However, the contributions from individual oil–gas facilities emitting at low emission rates that are often undetected are poorly understood, especially in the context of total national- and regional-level estimates. In this work, we compile empirical measurements gathered using methods with low limits of detection to develop facility-level estimates of total methane emissions from the continental United States (CONUS) midstream and upstream oil–gas sector for 2021. We find that of the total 14.6 (12.7–16.8) Tg yr−1 oil–gas methane emissions in the CONUS for the year 2021, 70 % (95 % confidence intervals: 61 %–81 %) originate from facilities emitting <100kgh-1 and 30 % (26 %–34 %) and ∼80 % (68 %–90 %) originate from facilities emitting <10 and <200kgh-1, respectively. While there is variability among the emission distribution curves for different oil–gas production basins, facilities with low emissions are consistently found to account for the majority of total basin emissions (i.e., range of 60 %–86 % of total basin emissions from facilities emitting <100kgh-1). We estimate that production well sites were responsible for 70 % of regional oil–gas methane emissions, from which we find that the well sites that accounted for only 10 % of national oil and gas production in 2021 disproportionately accounted for 67 %–90 % of the total well site emissions. Our results are also in broad agreement with data obtained from several independent aerial remote sensing campaigns (e.g., MethaneAIR, Bridger Gas Mapping LiDAR, AVIRIS-NG (Airborne Visible/Infrared Imaging System – Next Generation), and Global Airborne Observatory) across five to eight major oil–gas basins. Our findings highlight the importance of accounting for the significant contribution of small emission sources to total oil–gas methane emissions. While reducing emissions from high-emitting facilities is important, it is not sufficient for the overall mitigation of methane emissions from the oil and gas sector which according to this study is dominated by small emission sources across the US. Tracking changes in emissions over time and designing effective mitigation policies should consider the large contribution of small methane sources to total emissions.

The Impact of Trade Openness on Carbon Emissions: Empirical Evidence from Emerging Countries

Emerging countries are the main source of new CO2 emissions and the major net carbon importers, and they have also become an important part of the global trade pattern. In this study, the impact of trade openness on CO2 emissions was investigated by approaches such as fully modified least squares (FMOLS), dynamic ordinary least squares (DOLS), and pooled mean group-autoregressive distributive lag (PMG-ARDL) methods. Further estimations were conducted by employing methods such as DCCEMG (dynamic common-correlated effect mean group) and Driscoll–Kray to strengthen the robustness of the results. Moreover, the Granger causality between trade openness and CO2 emissions was tested by using the Dumitrescu–Hurlin method. Conclusions can be drawn as follows: First, economic growth, energy consumption, trade openness, and CO2 emissions are all interconnected in the long term. Specifically, higher levels of economic growth and trade openness are associated with lower CO2 emissions, whereas energy consumption contributes to higher emissions. However, in the short term, economic growth and energy consumption lead to an increase in CO2 emissions, while trade openness does not have a significant impact. Moreover, there is a two-way Granger causality between trade openness and CO2 emissions. Additionally, economic growth and energy consumption have an indirect effect on CO2 emissions by influencing trade openness. Given these findings, emerging market countries should focus on enhancing their service sectors, promoting technological advancements, and fostering international collaboration in green technologies. By actively engaging in efforts to combat climate change, these countries reach a point where trade expansion and carbon reduction are achieved.

PSR J1631–4722: The Discovery of a Young and Energetic Pulsar in the Supernova Remnant G336.7+0.5

Abstract Detecting a pulsar associated with a supernova remnant (SNR) and/or pulsar wind nebula (PWN) is crucial for unraveling its formation history and pulsar wind dynamics, yet the association with a radio pulsar is observed only in a small fraction of known SNRs and PWNe. In this paper, we report the discovery of a young pulsar J1631–4722, associated with the Galactic SNR G336.7+0.5 using Murriyang, CSIRO’s Parkes radio telescope. It is also potentially associated with a PWN revealed by the Rapid ASKAP (Australian Square Kilometre Array Pathfinder) Continuum Survey (RACS). This 118 ms pulsar has a high dispersion measure of ∼873 pc cm−3 and a rotation measure of –1004 rad m−2. Because of such a high DM, at frequencies below 2 GHz, the pulse profile is significantly scattered, making it effectively undetectable in previous pulsar surveys at ∼1.4 GHz. Follow-up observations yield a period derivative of Ṗ = 5.5× 10−14, implying a characteristic age, τc = 33.9 kyr, and spin-down luminosity, Ė = 1.3× 1036 erg s−1. PSR J1631–4722, with its high spin-down luminosity and potential link to a PWN, stands out as a promising source of the high-energy γ-ray emission observed in the region.

Predicting carbon peak at the provincial level using deep learning

Abstract Assessing carbon peak status is crucial in designing mitigation strategies for provinces to mitigate CO2 emissions while maintaining economic development. This study proposes a comprehensive research framework to evaluate carbon peak status at the provincial level. The framework involves identifying the critical emission sources and their primary contribution sectors using the LASSO regression method, predicting the CO2 emissions of critical sources using recurrent neural networks, and exploring mitigation schemes using scenario analysis. This study uses Guizhou Province as an example and analyzes the CO2 emissions of 17 energy consumption types and one production process in 47 socio-economic sectors and discovers that: ① Between 1997 and 2005, the most critical sources of CO2 emissions were the consumption of Raw Coal; ② Between 2006 and 2021, the critical sources of emissions were the consumption of Raw Coal, Other Washed Coal (OWC), and Diesel Oil, and one industry process (Cement Production Process, CPP); ③ Between 2006 and 2021, the primary contribution sector for Raw Coal and OWC emissions is the Production and Supply of Electric Power, Steam, and Hot Water (PSEPSHW) sector. The main contributors to Diesel Oil emissions are the Transportation, Storage, Post and Telecommunication Services (TSPTS), and Other Services (OS) sectors. This study projects that the rising trend in total CO2 emissions will continue from 2022 to 2040 and that emissions will not yet reach their peak by 2030. Furthermore, CO2 emissions from Raw Coal consumption and CO2 emissions from Diesel Oil consumption will continue to increase. These are crucial when designing mitigation schemes for total CO2 emissions. The scenario analysis presents three mitigation schemes for Raw Coal and Diesel Oil emissions that have the potential to reverse the upward trend in CO2 emissions.

New evidence on the nephrotoxicity of fine particulate matter: Potential toxic components from different emission sources.

Associations exist between fine particulate matter (PM2.5) exposure and impaired kidney function. However, the specific mechanisms and components causing renal damage remain unclear. PM2.5 was collected from an industrial and a rural area. Mice were categorized according to exposure, and biochemical, western blotting, histological, and immunohistochemical analyses were performed to evaluate the impact of PM2.5 constituents on their kidneys. To assess the impact of different PM2.5 components on inflammatory responses, a study was conducted by exposing the murine macrophage cell line (RAW 264.7). The study used a chelating resin to remove the influence of heavy metals from the water extract and employed a Toll-like receptor 4 (TLR4) antagonist to eliminate the effects of endotoxin, thereby evaluating the cellular inflammatory responses induced by various PM2.5 components. The major metallic elements at the industrial site were Fe, Mg, Zn, and Ca, whereas those at site Rural were Ca, K, and Mg. PM2.5 water extracts from both sites induced inflammatory cytokine upregulation in the lungs and kidneys, and inflammatory cell infiltration, antioxidant activity downregulation, and elevated levels of kidney injury molecule 1 in the kidneys. Exposure to PM2.5 water extract increased the mRNA levels of tumor necrosis factor-α, interleukin-6, and nitrite production in RAW264.7 macrophages. The inflammatory response and nitrite production induced by the industrial-site PM2.5 water extract were significantly suppressed after treatment with a chelating resin, whereas those from the rural area were suppressed by the Toll-like receptor 4 (TLR4) antagonist. These results suggest that heavy metals are crucial factors in PM2.5-induced cellular inflammatory responses in industrial areas, whereas endotoxin receptor--TLR4 mediated inflammatory pathways are the primary factor responsible for this response in rural areas. Furthermore, at equivalent dosages, the renal toxicity induced by the water-soluble components of rural-site PM2.5 may exceed that from industrial areas.

Understanding double perovskite BCNF as a CO2 splitting catalyst for industrial decarbonisation

The foundation industry, particularly the steel sector, is one of the major sources of global CO2 emissions, with each ton of steel produced using iron ores contributing approximately 1.4 (direct reduced iron-based process) to 2 (blast furnace-based process) tons of CO2, with ironmaking accounting for approximately 70% of these emission. Here, we present a study on the potential of using a double perovskite, Ba2Ca0.66Nb0.34FeO6-δ (BCNF), as a CO2 splitting catalyst that converts CO2 into carbon monoxide (CO), a reducing agent in ironmaking, which can be reintegrated into the ironmaking process to enable ‘in-process’ decarbonisation and facilitate close-loop carbon recirculation. The study combines thermodynamic modelling, molecular dynamics simulations, material characterisation, and lab-scale experimental system design, demonstrating the efficiency and practicality of the use of BCNF for CO2 emission reduction at a moderate temperature range. Simultaneous Thermal Analysis and COMSOL-based simulations were employed to optimise reactor design, maximising CO yield. An economic analysis further supports the scalability of this technology for decarbonising the steelmaking industry, which bears significance with the broader applicability to other foundation industrial sectors, including non-ferrous metal smelting, cement, glass, ceramics, and chemicals. This innovation offers a promising pathway towards sustainable industrial practices and contributes to global efforts to address climate change challenges.Graphical

Greenhouse gas emissions due to inhalation anaesthetics in the Netherlands, usage data and a survey of preferences among Dutch anaesthesiologists.

Anaesthetic gases are an important source of greenhouse gas emissions from operating theatres and can attribute significantly to the carbon footprint of a nation's healthcare system. To estimate the magnitude of the climate impact of inhaled anaesthetics in the Netherlands. Furthermore, the goal was to assess the preferences of Dutch anaesthesiologists for anaesthesia techniques, and to explore opportunities for reducing greenhouse gas emissions due to anaesthesia practice. A 2019 bottom-up purchase analysis of inhalation anaesthetics used in all of the Dutch hospitals was executed and an online survey was conducted among Dutch anaesthesiologists regarding their preferences for anaesthetic agents. Purchasing quantities of volatile anaesthetic agents were obtained from 61 of the 69 hospital organisations in the Netherlands (response rate 88.4%). A total of 12.2 kilotons CO2 equivalent (0.07% of the Dutch healthcare system) was emitted due to inhalation anaesthetics in the Netherlands in 2019. The volume of the in 2019 purchased inhalation volatile anaesthetics was 9.178 l of sevoflurane (93.4%), 404 l of desflurane (4.1%) and 245 l of isoflurane (2.5%). The survey in which 182 anaesthesiologists participated demonstrated that propofol was the first drug of choice of 70% of respondents, desflurane was available in 16% of Dutch hospitals and 83% of anaesthesiologists answered never using desflurane. Nitrous oxide was not used by 63% of respondents, the remaining 27% reported using nitrous oxide only in less than 5% of their cases. The relatively low emission of greenhouse gases due to inhalation anaesthetics in Dutch healthcare compared to other countries can be explained by the limited use of nitrous oxide and desflurane by Dutch anaesthesiologists and their strong preference for intravenously administered propofol as an anaesthetic.

Comprehensive Assessment, Intelligent Prediction, and Precise Mitigation Strategies for Greenhouse Gas Emissions in Full-Scale Wastewater Treatment Plants.

Wastewater treatment plants (WWTPs) are major contributors to global anthropogenic greenhouse gas (GHG) emissions, with China ranks among the leading emitters. In the context of China's "dual-carbon" journey, precision quantification and predictive forecasting of GHG fluxes, particularly methane (CH4) and nitrous oxide (N2O)-are crucial for developing advanced mitigation strategies of WWTPs. To accurately assess GHG emissions, this study firstly introduced customized emission factors (EFs) to precisely evaluate the GHG emissions of a full - scale A2O - based WWTP in Beijing. This approach addressed the overestimation of emissions when using the IPCC's standard EFs. Additionally, the study proposed machine learning (ML) techniques to predict GHG fluxes based on routine wastewater quality parameters. Specifically, Long Short-Term Memory (LSTM) and Random Forest (RF) models showed the strong performance in predicting CH4 and N2O emissions, respectively. Moreover, our findings revealed distinct spatiotemporal patterns of GHG emission: CH4 emissions peak during the summer solstice, while N2O emissions rise during the winter months. For the first time, this study identified the nitrification biofilter in the advanced treatment unit as a significant direct source of N2O emissions. Eventhough, indirect CO2 emissions account for a dominant 57%-90% of the total GHG emissions. Scenario analyses revealed a strategic mitigation approach. Energy conservation emerged as the most effective measure, capable of reducing emissions by 23.41%, followed by heat recovery, which could cut emissions by 10.15%. In practical applications, improving energy efficiency is of utmost importance in real - world mitigation strategies. This highlights the significance of integrated approaches for achieving the sustainable development of WWTPs in the "dual - carbon" background.

Regional Differences, Convergence Characteristics, and Carbon Peaking Prediction of Agricultural Carbon Emissions in China

As a major agricultural country, agricultural carbon emissions in China are one of the key areas of focus for achieving China's “dual carbon” targets. This study utilizes the Dagum Gini coefficient, convergence models, and the ARIMA model to analyze the characteristics of agricultural carbon emissions in China's three major grain production functional zones. The results show that: (1) The agricultural carbon emissions in the national, main grain-production, and main grain-sales regions exhibit a fluctuating decreasing trend, while the agricultural carbon emissions in the grain production-sales balance region show a fluctuating increasing trend. The primary sources of agricultural carbon emissions are agricultural material inputs and enteric fermentation of ruminants. (2) The intra-regional differences in agricultural carbon emissions are the largest in the main grain-sales region, followed by the grain production-sales balance region, and the smallest in the main grain-production region. The contribution rate of inter-regional differences is the highest, making it the main source of overall disparity, while the contribution rate of hyperbolic density is the lowest. (3) Both the national level and the three major grain production functional zones exhibit conditional β-convergence in agricultural carbon emissions, indicating that the agricultural production in the national, main grain-production, and main grain-sales regions shows a “carbon neutral” characteristic, while the agricultural production in the grain production-sales balance region shows a “carbon peak” characteristic. (4) The agricultural carbon peak in China occurred in 2015, with a total carbon emission of 164.5 million tons. The main grain-production and main grain-sales regions have already reached carbon peak, while the grain production-sales balance region is expected to reach its carbon peak by 2030.

More biomass burning aerosol is being advected westward over the southern tropical Atlantic since 2003.

Each year, agricultural fires in southern continental Africa emit approximately one third of the world's biomass burning aerosol. This is advected westward by the prevailing circulation winds over a subtropical stratocumulus cloud deck. The radiative effects from the aerosol and aerosol-cloud interactions impact regional circulations and hydrology. Here we examine how concurrent changes in the burning season and regional climate in southern Africa over the past 18years (2003-2020) impact the southeast Atlantic. We combine satellite-derived burned area datasets (GFEDv5 primarily) with ECMWF-reanalysis carbon monoxide (CO), black carbon, and meteorology from the biomass burning season (May-October) in southern Africa. The burning season begins in May in woody savannas in the northwest and shifts to open savanna and grassland fires in the southeast, with small fires (<1km2) contributing significantly to total burned area. In the most recent decade, more small fires are occurring in the middle of the biomass burning season and the overall season is shorter, corroborated by reanalysis carbon monoxide fields. Free tropospheric winds, also known as the Southern African easterly jet, increase significantly and shift southward, transporting smoke aerosol further southwest over the southeast Atlantic. The advection increases middle-tropospheric CO by 5% of the total column per decade, and is coupled with a southern shift in the south Atlantic subtropical high and an increase in the low cloud fraction on the southern edge of the stratocumulus cloud deck. While smoke emissions sources have not changed significantly, changes in the smoke transport pathway, attributed to increasing surface temperatures in southern Africa and tropical expansion, combined with an altered low cloud distribution, explain how the all-sky shortwave top-of-atmosphere direct aerosol radiative effect has become more positive - a climate warming - in recent decades.

Volatile organic compounds at a highland forest site in the southeast of the Tibetan Plateau: Source apportionment and reactivity contributions

Atmospheric volatile organic compounds (VOCs) are reactive species and the primary precursors of free radicals; thus, VOCs play important roles in tropospheric chemistry. Tibet field campaigns from April 4 to May 11, 2021 found high mixing ratios and reactivity contributions of oxygenated VOCs (OVOCs) at Lulang, a site with high vegetation cover and strong solar ultraviolet radiation on the southeast of the Tibetan Plateau (TP). The 13 OVOCs detected accounted for 49% of the total VOCs (TVOCs), with a mean mixing ratio (±1σ) of 11.7 ± 4.4 ppb. These OVOCs exhibited typical diurnal variation, with high values in the daytime and a peak at approximately 12:00. OVOCs contributed 65% and 63% to VOC-kOH and the ozone formation potential, respectively. Two independent methodologies were employed to determine the contributions of various sources and revealed concordant conclusions regarding the importance of biological sources there. The source apportionment results obtained through positive matrix factorization indicated that sunlight-impacted and direct plant emission sources both related to plant sources contributed 47% of the TVOCs and 65% of the OVOCs. OVOC source fitting through the photochemical age parameterization method also indicated that biogenic sources made the largest contribution (67%) to OVOCs and revealed a clear peak at noon. In addition, biomass burning sources were found to be closely related to the VOC background because biomass burning is highly prevalent across the whole TP; these sources made the second greatest contribution (33%) to the TVOCs and contributed more than 23% of OVOCs. Our findings enhance comprehension of VOCs in the highland forest region, potentially impacting tropospheric chemistry significantly.

Long-term temporal response of eastern canadian lakes chemistry along a large spatial gradient of atmospheric sulfate deposition.

A major consequence of the Industrial Revolution was the acidification of continental water bodies by sulfates (SO42-) and nitrates deposited over long-range distance from atmospheric emissions. Regulation policies were implemented in the 1980s leading to the general decrease of SO42- concentrations in freshwaters and progressive recovery from acidification, a complex process that is still ongoing. The surface water SO42- decrease has been linked to declining calcium (Ca2+) and increasing dissolved organic carbon (DOC) concentration. Here, up to 40 years (1983-2023) of chemical data in 46 lakes of Eastern Canada are analyzed for long-term trends and spatial patterns along a large gradient of SO42- deposition. The average lake SO42- concentration decreased along the distance from sulfur dioxide sources. SO42- concentration decreased significantly in every lake and faster close to the emission sources. In 70% of the lakes, the SO42- decline drove concurrent but slower Ca2+ and magnesium declines, leading to an overall increase in the Ca2+/SO42- ratio, in pH and in alkalinity for 72% of the lakes. The Ca2+ concentration is now below the crucial threshold for large zooplankton species in most lakes. Increasing trends in lake sodium concentration suggest an intensification of mineral weathering in catchment soils, potentially linked to rising temperatures, which could be involved in the observed recovery. DOC increased in 67% of lakes which drove a concurrent increase in aluminum in some lakes. The numerous environmental changes in progress across temperate and boreal lakes will deeply modify the structure and functioning of these systems, especially in the context of climatic changes.