Equivalent Carbon Research Articles

Multiyear high-temporal-resolution measurements of submicron aerosols at 13 French urban sites: data processing and chemical composition

Abstract. This paper presents a first comprehensive analysis of long-term measurements of atmospheric aerosol components from aerosol chemical speciation monitor (ACSM) and multiwavelength Aethalometer (AE33) instruments collected between 2015 and 2021 at 13 (sub)urban sites as part of the French CARA (Chemical Characterization of Particles) program. The datasets contain the mass concentrations of major chemical species within submicron aerosols (PM1), namely organic aerosols (OAs), nitrate (NO3-), ammonium (NH4+), sulfate (SO42-), non-sea-salt chloride (Cl−), and equivalent black carbon (eBC). Rigorous quality control, technical validation, and environmental evaluation processes were applied, adhering to both guidance from the French Reference Laboratory for Air Quality Monitoring (LCSQA) and the Aerosol, Clouds, and Trace Gases Research Infrastructure (ACTRIS) standard operating procedures. Key findings include geographical differences in the aerosol chemical composition, seasonal variations, and diel patterns, which are influenced by meteorological conditions, anthropogenic activities, and proximity to emission sources. Overall, OA dominates PM1 at each site (43 %–60 % of total mass), showing distinct seasonality with higher concentrations (i) in winter, due to enhanced residential heating emissions, and (ii) in summer, due to increased photochemistry favoring secondary aerosol formation. NO3 is the second most important contributor to PM1 (15 %–30 %), peaking in late winter and early spring, especially in northern France, and playing a significant role during pollution episodes. SO4 (8 %–14 %) and eBC (5 %–11 %) complement the major fine-aerosol species, with their relative contributions strongly influenced by the origin of air masses and the stability of meteorological conditions, respectively. A comparison with the 3D chemical transport model (CTM) CHIMERE shows high correlations between simulations and measurements, albeit with an OA concentration underestimation of 46 %–76 %. Regional discrepancies in NO3 concentration levels emphasize the importance of these datasets with respect to validating air quality models and tailoring air pollution mitigation strategies. The datasets can be found at https://doi.org/10.5281/zenodo.13318298 (Chebaicheb et al., 2024).

Kinetics of Cd adsorption by biochar, activated carbon, and zeolite in some calcareous soils

AbstractDifferent methods have developed to reduce the risks of potentially toxic elements in contaminated soils. Among them, adsorption is one of the most important and effective strategies. In this research, kinetics of Cd adsorption by biochar, activated carbon, and zeolite in some calcareous soils were investigated. A factorial experiment was conducted based on a completely randomized design with three replications. The factors included three types of adsorbents (sunflower's biochar, activated carbon, and zeolite), four levels of Cd (0, 20, 50, and 100 mg/L as Cd (NO3)2), and three soil samples, differing in their cation exchange capacity, soil organic matter, and calcium carbonate equivalent. Batch experiments were carried out to evaluate Cd adsorption isotherms and kinetic models. Furthermore, the effect of adsorbent dosage, contact time, and initial pH on the adsorption efficiency was examined. Optimizing studies revealed that the best pH for Cd adsorption was 5, while the optimal equilibrium time was achieved at 24 h. The results showed that the Freundlich model fitted to the experimental data slightly better than the Langmuir model. Moreover, the pseudo‐second‐order kinetic model better described the kinetic behavior of Cd adsorption for the investigated adsorbents. The maximum Cd removal efficiency (99%) belonged to soil No. 2 with biochar. Lastly, it was concluded that sunflower biochar, a cheap and cost‐effective adsorbent, had high efficiency in Cd adsorption in calcareous soils.

The impact of long-term organic horticultural systems on energy outputs and carbon storages in relation to extreme rainfall events

Enhancing resilience of agroecosystems of Mediterranean area is a challenge that involves both researchers and different stakeholders and, in this context, increasing crop diversity by redesigning agricultural systems can be considered among the most important tools. Therefore, the response of agroecological practices to climate change effects was tested in a long-term experiment on organic horticultural crops (MITIORG), which is characterized by a soil hydraulic arrangement in ridges, strips and the use (with different management options) of cover crops within cash crops rotations. The main objective of this study was to show how powerful is the sustainability assessment of agroecological practices by converting crops yield and biomass into energy outputs and carbon storages, in diversified horticultural systems. The obtained outputs (expressed in energy and carbon equivalents) were evaluated and analyzed considering the site-specific meteorological data in more than 10 horticultural cropping cycles, from autumn-winter 2014-15 to autumn-winter 2020-21. The Ridge and Strips (RS) system 1 (RS1 - cover crops as living mulch on ridges and break crops in strips, both with no-till termination) showed an enhancement of about 18% of energy output and carbon (C) storages compared to RS2 (ridges and strips with green manured cover) when extreme precipitation events occurred. Moreover, RS3 (ridges and strips without cover crops) recorded a reduction of about 5 and 9% of energy output and C storage, respectively, compared to the mean of RS1 and RS2 in periods with extreme events. Our results highlighted that using more diversified agroecological systems improved their overall average outputs, ensuring greater resilience during extreme weather events, since at least part of crop productions was safeguarded. Therefore, it is important to combine techniques that allow long-term resilience, such as choosing and well managing cover crops (agroecological service crops), according to site and systems specific conditions.

Investigation on the methane emissions from permeation of urban gas polyethylene pipes under the background of hydrogen-mixed natural gas transportation

Methane, a more potent greenhouse gas than carbon dioxide, aggravates the greenhouse effect of ecological environment through its emissions. When transporting hydrogen-mixed natural gas through urban polyethylene pipes, methane will be emitted due to the permeation characteristic of polyethylene pipe material. Therefore, it is crucial to pay attention to the methane emissions from permeation of polyethylene pipes for protecting the environment and climate. In this paper, the solubility and diffusion coefficients of methane within hydrogen-mixed natural gas in polyethylene pipe materials are calculated through the Monte Carlo method and molecular dynamics simulation to determine the permeation coefficient of methane. Simultaneously, the methane emissions and equivalent carbon dioxide emissions of the hydrogen-mixed natural gas in polyethylene pipes are investigated. Results indicate the methane solubility coefficient decreases with increasing temperature and hydrogen mixing ratio. The methane diffusion and permeation coefficients increase with the rising temperature and pressure, and decreasing hydrogen mixing ratio. The pressure exerts minor influence while the temperature and hydrogen mixing ratio have more significant impact. That is, the lower the temperature and the higher the hydrogen mixing ratio, the less methane emissions caused by permeation. Therefore, the effective reduction of methane emissions can be achieved by adding the insulation layer to mitigate the impact of high temperature and increasing the hydrogen mixing ratio. For example, for the polyethylene pipe with the operating pressure of 4 bar and the size specification of SDR11, when the temperature drops from 300 K to 260 K, the methane emissions of hydrogen-mixed natural gas with hydrogen mixing ratios of 0 vol%, 20 vol%, 50 vol% and 80 vol% will be drastically reduced by 73.3%, 74.4%, 77.2% and 78.5% respectively, and when 20 vol%∼80 vol% hydrogen are mixed in the natural gas at 260 K, 300 K and 310 K, the methane emissions will be effectively reduced by 26.7%∼85.6%, 23.3%∼82.1% and 23.9%∼82.4% respectively. The findings of this study can serve as guidance for reducing the methane emissions from permeation of polyethylene pipes transporting hydrogen-mixed natural gas.

Microstructure evolution and mechanical properties of martensitic stainless bearing steels with different carbon nitrogen ratios

This study investigates the effect of adjusting the carbon nitrogen ratio on the microstructure and mechanical properties of martensitic stainless bearing steels, keeping the equivalent total carbon and nitrogen content. The results demonstrate that the sample with nearly equal weight percentages of C and N exhibits optimal comprehensive performance, achieving impressive yield strength, ultimate tensile strength, and uniform elongation of up to 1806.5 MPa, 2279.3 MPa, and 4.5%, respectively. Distinct phase ratios and morphologies observed across the three C/N ratios after identical heat treatment process suggest varying intrinsic mechanisms due to differences in C and N solid solubility in the matrix. The specimen with almost balanced C and N shows the highest interstitial atom solubility in the austenite phase, stabilizing austenite and lowering stacking fault energy. Abundant fine twins in martensite and stacking faults in austenite contribute to increased elongation without compromising strength. In contrast, specimen with higher N/C ratio exhibits numerous nitrides, limiting N atom solid solution in austenite during austenization, resulting in martensite with twins and dislocations. Specimen with higher C/N ratio shows extensive carbide precipitation and mainly dislocation-type martensite. The study deepens the understanding of C and N interactions in advanced bearing steels and provides a foundation for improving mechanical properties of such steels.

Atmospheric black carbon in the metropolitan area of La Paz and El Alto, Bolivia: concentration levels and emission sources

Abstract. Black carbon (BC) is a major component of submicron particulate matter (PM), with significant health and climate impacts. Many cities in emerging countries lack comprehensive knowledge about BC emissions and exposure levels. This study investigates BC concentration levels, identifies its emission sources, and characterizes the optical properties of BC at urban background sites of the two largest high-altitude Bolivian cities: La Paz (LP) (3600 m above sea level) and El Alto (EA) (4050 m a.s.l.), where atmospheric oxygen levels and intense radiation may affect BC production. The study relies on concurrent measurements of equivalent black carbon (eBC), elemental carbon (EC), and refractory black carbon (rBC) and their comparison with analogous data collected at the nearby Chacaltaya Global Atmosphere Watch Station (5240 m a.s.l). The performance of two independent source apportionment techniques was compared: a bilinear model and a least-squares multilinear regression (MLR). Maximum eBC concentrations were observed during the local dry season (LP: eBC = 1.5 ± 1.6 µg m−3; EA: 1.9±2.0 µg m−3). While eBC concentrations are lower at the mountain station, daily transport from urban areas is evident. Average mass absorption cross sections of 6.6–8.2 m2 g−1 were found in the urban area at 637 nm. Both source apportionment methods exhibited a reasonable level of agreement in the contribution of biomass burning (BB) to absorption. The MLR method allowed the estimation of the contribution and the source-specific optical properties for multiple sources, including open waste burning.

Assessment of vehicle exhaust PM emissions using high-resolution on-road measurements in Seoul, Korea

In megacities, road traffic is a major source of particulate matter (PM), requiring a critical understanding of effective air pollution control. Despite existing methods to determine PM emission factors (EFs) of vehicles, accurate estimation of PM emissions under real driving conditions remains challenging. We aimed to assess the EFs of organic aerosol (OA) and equivalent black carbon (eBC) from vehicles through on-road measurements in Seoul, Korea, to understand real-world PM emissions. We used a mobile laboratory equipped with an aerosol mass spectrometer and an aethalometer to measure the composition of PM. On-road measurements were conducted in vehicle tunnels, urban roadways, and residential areas, and the characteristics of measurement points were compared and analyzed. Our results showed that concentrations of OA increased proportionally with the influence of vehicle exhaust, while oxidation states of the OA decreased. Mobile measurements revealed spatial heterogeneities in aerosols, highlighting distinct characteristics of fresh OA on vehicle roads and elevated oxidation state values in residential areas. Active nitrate formation near vehicles led to elevated NO3 concentrations on roads compared to residential areas. Our study shows that mobile PM measurements, including OA and eBC, are valuable for the direct evaluation of emission inventories. However, given that the calculated EFs may not be applicable to other cities due to differences in vehicle composition and traffic conditions, the development of city-specific EFs will be necessary in the future. Furthermore, it is recommended to integrate this methodology with conventional emission inventories to identify vehicle-type-specific emissions.Graphical

Modeling of Carbon Footprint Emissions in Sugarcane Production Using System Dynamics

Objective: This study proposes a model aimed at estimating and reducing carbon emissions in sugarcane cultivation and juice extraction, designed for potential application in real-world systems. Method: The model grounded in a hypothetical case study of a 60-hectare sugarcane plantation in a warm climate with a 7-month growth cycle and a three-year simulation period, focuses on estimate and evaluate mitigation scenarios to decrease emissions from fuel and electricity usage in activities such as plowing, sowing, harvesting, and irrigation. Utilizing Vensim PLE, a System Dynamics model that combine event and dynamic simulation. Results and Discussion: Utilizing Vensim PLE, a System Dynamics model that combine event and dynamic simulation estimated a 3060.81 tons CO2 equivalent carbon footprint. Two scenarios aimed at footprint reduction were tested: substituting electrical energy with solar power reduced the footprint by 86% to 450.092 tons, demonstrating clean energy's efficacy. Conversely, replacing an industrial mill with the traditional trapiche technique for juice extraction yielded a mere 1% reduction, indicating its ineffectiveness for real-world application. Research Implications: This study emphasizes the development of a simulation model based on system dynamics to estimate the carbon footprint emissions in sugar cane production considering its cultivation and juice extraction. The results support that through simulations, it is possible to determine the factors that influence the generation of carbon dioxide, offering a broader vision to establish and implement mitigation measures such as adopting clean energies and reducing fuel consumption. Originality/Value: This research contributes to the understanding of the application of system dynamics by using software such as Vensim PLE to estimate the carbon footprint emissions in sugar cane production, considering its cultivation and juice extraction. The results found through simulations suggest the implementation of mitigation measures such as the adoption of clean energies and the reduction of fuel consumption.

Cross-Coupling of NHC/CAAC-Based Carbodicarbene: Synthesis of Electron-Deficient Diradicaloids.

Herein, we report nickel(0)-catalyzed cross-coupling reactions of NHC/CAAC-based carbodicarbene (NHC = N-heterocyclic carbene and CAAC = cyclic(alkyl)(amino)carbene) with different aryl chlorides, bromides, and iodides. The resulting aryl-substituted cationic carbodicarbene derivatives are prone to one-electron oxidation yielding radical-dications, which, depending on the aryl motif employed, follow different modes of radical-radical dimerization and constitute an entry point to carbon/nitrogen- and nitrogen/nitrogen-centered diradicaloids. Subsequently, this coupling strategy was strategically applied to the synthesis of p-phenylene- and p,p'-biphenylene-bridged carbon/carbon-centered electron-deficient diradicaloids. The employed π-conjugated spacer plays a crucial role in determining the triplet population at room temperature by modulation of the singlet-triplet gap: EPR inactive for p-phenylene vs EPR active for p,p'-biphenylene. Nearly two decades after the disclosure of carbodicarbenes as donor-stabilized atomic carbon equivalents by Tonner and Frenking in 2007, we demonstrate their cross-couplings with a series of aryl halides/dihalides and, based on this, developed a modular methodology for the systematic synthesis of various electron-deficient diradicaloids.

Skeletal Editing of Indoles and Pyrroles Enabled by a Novel, Atomic Carbon Equivalent

Skeletal Editing of Indoles and Pyrroles Enabled by a Novel, Atomic Carbon Equivalent

Self-Oxidated Hybrid Conductive Network Enables Efficient Electrochemical Lithium Extraction Under High-Altitude Environment.

The electrochemical deintercalation method has been considered as an effective way to address the demand for lithium resources due to its environmental friendliness, high selectivity, and high efficiency. However, the performance of electrochemical lithium extraction is closely dependent on the electrode material and needs to be compatible under plateau environments with high-altitude and low-temperature. Herein, an in situ self-oxidation method is conducted to construct a hybrid conductive network on the surface of LiFePO4 (LFP-HN). The introduction of a hybrid conductive network enhanced the interfacial electron/lithium-ion transfer. In addition, structural stability is strengthened through suppressing the intercalation of impurity cations. Consequently, the LFP-HN delivered extremely high lithium extraction capacity (27.42mg g-1), low energy consumption (4.91Wh mol-1), and superior purity (91.05%) in Baqiancuo real brine (4788 m, -10°C). What's more, LFP-HN-based large-scale prototypes are constructed and operated at Baqiancuo, which is calculated to extract 25kg Lithium Carbonate Equivalent per cycle (4.55h, 100 pairs of plates). Based on the excellent performance, the modification strategy developed in this work can be a promising solution for industrial lithium extraction under high-altitude environment.

Mechanism of o-cresol polymerization and its carbon recovery from aqueous solution by a cathode/Fe2+/H2O2 process

Converting organic pollutants into easily recyclable solid polymers has the advantages of saving oxidants and recovering organic carbon, compared to degrading them into smaller organic molecules. Taking o-cresol as a representative phenolic pollutant, this study realizes the dominant reaction of organic polymerization and the recovery of organic carbon from wastewater via a cathode/Fe2+/H2O2 process. With HO• initiation, 53 % of chemical oxygen demand is removed in the form of suspended solid polymers and equivalent organic carbon is recovered. At the same time, the dissolved organic carbon (DOC) removal reaches 64 %, and the H2O2 consumption is only a quarter of that in an ideal degradation process. The recovered solid polymers are oligomers derived from o-cresol and its derivatives, with the molecular weight ranging from 400 to 2500 Da. The polymerization pathway involves repeated HO• oxidation and coupling of intermediate organic radicals. The energy consumption is 26.7 kWh/kg DOC, significantly lower than that of previous Fenton-like processes in the literature. This study broadens the scope of polymerization-based technologies for organic wastewater treatment, and demonstrates that HO• has the potential to simultaneously reduce organic pollution and recover organic carbon by generating suspended solid organic polymers, which may provide new avenues for H2O2-based Fenton processes toward resource recovery and water purification.

Multi-site comparison and source apportionment of equivalent Black Carbon mass concentrations (eBC) in United States: Southern California Basin and Rochester, New York,

Spatial and temporal variability of equivalent black carbon (eBC) mass concentrations were studied using Aethalometers (AE33 and AE21) at 10 sites, including 5 urban and 5 near-road across the south coast of California and New York-Rochester. Statistical methods were applied to perform intra-urban and multi-site comparisons. Given that nominal eBC values provided by the Aethalometer were significantly overestimated, eBC concentrations were corrected using an appropriate multiple-scattering enhancement correction factor (C0) to accurately calculate light absorption. Annual and seasonal variations highlighted the significant contributions of traffic emissions to eBC mass concentrations at all sites. Source apportionment using the Aethalometer approach demonstrated that fuel combustion—primarily from gasoline and diesel vehicles— accounted for up to 80% of eBC emissions. Emission sources were found to be largely region specific. Our findings suggest that the implementation of restrictive regulations aimed at reducing gasoline and diesel vehicle emissions, such as California's Tier 3 (SULEV, 2015) and New York (2017), has led to a higher proportion of cleaner, emission-controlled vehicles in the South Coast Air Basin compared to Rochester. However, the effects of these measures may require more time to be fully observed in traffic-polluted areas across the US.

NON-DESTRUCTIVE METHOD OF IDENTIFICATION OF STEEL GRADES OF ROLLING PRODUCTS

This article presents the results of coercive force dependence study of on the chemical composition and geometric parameters for the purpose of identifying the steel grade in a non-destructive manner. The paper proposes to identify the steel grade by the coercive force, using a correlation with the carbon equivalent and the diameter of the rolled product. As a result of the work, the possibility of identifying steel grades by the carbon equivalent associated with the coercive force and the diameter of the product was established. The ranges of the carbon equivalent for steels St3, 18Mn2Si and 30CrMn2Si were determined. The results of the work established that the coercive force depends on the chemical composition and geometric parameters of the controlled product. Thus, the solutions proposed in this paper are of great practical importance for industrial enterprises for the purpose of steel products prompt identification. The obtained values ​​of the carbon equivalent derived from the proposed dependence correspond to the values ​​of the carbon equivalent calculated according to the standard GOST R 55020-2012. This method of non-destructive determination of steel grade by carbon equivalent through magnetic parameters can be applied to products made of tool and other structural steel grades. Keywords: non-destructive testing, coercive force, carbon equivalent, regression, magnetic properties.

Lure Monitoring for Mediterranean Fruit Fly Traps Using Air Quality Sensors.

Effective pest population monitoring is crucial in precision agriculture, which integrates various technologies and data analysis techniques for enhanced decision-making. This study introduces a novel approach for monitoring lures in traps targeting the Mediterranean fruit fly, utilizing air quality sensors to detect total volatile organic compounds (TVOC) and equivalent carbon dioxide (eCO2). Our results indicate that air quality sensors, specifically the SGP30 and ENS160 models, can reliably detect the presence of lures, reducing the need for frequent physical trap inspections and associated maintenance costs. The ENS160 sensor demonstrated superior performance, with stable detection capabilities at a predefined distance from the lure, suggesting its potential for integration into smart trap designs. This is the first study to apply TVOC and eCO2 sensors in this context, paving the way for more efficient and cost-effective pest monitoring solutions in smart agriculture environments.

Carbon Stock and Chemical Fractionation of Organic Matter in Different Soil Management Systems in the Bahian Cerrado

ABSTRACT Determining total organic carbon and its stock and quantifying the chemical fractions of soil organic matter can be used as indicators of the quality of the soil management used in a cropping area. This study aimed to quantify soil organic matter’s carbon stock and chemical fractions in different soil management systems used in the western Bahian Cerrado, Brazil, and compare them to a native Cerrado area. Ten microregions (Alto Horizonte, Anel da Soja, Bela Vista, Cascudeiro, Coaceral, Novo Paraná, Panambi, Placas, Roda Velha, Roda Velha de Baixo), three soil management systems [tillage system (TS), no-tillage systems (nTS), native Cerrado (NC)], and two soil layers (0–0.1 and 0.1–0.2 m) were studied. Soil bulk density (Sd), soil organic matter (SOM), total organic carbon (TOC), SOM quantification (qSOM), equivalent carbon stock (EqCs), humin (HF), humic acid (HAF) and fulvic acid (FAF) fractions from SOM were evaluated. The results indicated that Sd in all evaluated microregions was below the critical upper limit that would restrict plant root development. SOM, TOC, EqCs, and qSOM revealed increasing results following the TS, nTS, and NC order. The NC area presented the highest soil organic fraction contents (HF, HAF, and FAF). The microregions with better soil quality for all evaluated parameters were Coaceral and Cascudeiro; the lowest soil quality was observed in Alto Horizonte. The present study indicates that conservation agricultural management, such as the no-tillage system, improves the structure and composition of SOM parameters over time.

Indoor Air Quality at an Urban Primary School in Madrid (Spain): Influence of Surrounding Environment and Occupancy.

Monitoring indoor air quality (IAQ) in schools is critical because children spend most of their daytime inside. One of the main air pollutant sources in urban areas is road traffic, which greatly influences air quality. Thus, this study addresses, in depth, the linkages of meteorology, ambient air pollution, and indoor activities with IAQ in a traffic-influenced school situated south of Madrid. The measurement period was from 22 November to 21 December 2017. Simultaneous measurements of indoor and outdoor PM1, PM2.5, and PM10 mass concentrations, ultrafine particle number concentration (PNC) and equivalent black carbon (eBC) were analyzed under different meteorological conditions. PNC and eBC outdoor concentrations and their temporal trend were similar among the sampling points, with all sites being influenced in the same way by traffic emissions. Strong correlations were found between indoor and outdoor concentrations, indicating that indoor pollution levels were significantly affected by outdoor sources. Especially, PNC and eBC had the same indoor/outdoor (I/O) trend, but indoor concentrations were lower. The time delay in indoor vs. outdoor concentrations varied between 0.5 and 2 h, depending on wind speed. Significant differences were found between different meteorological conditions (ANOVA p-values < 2.14 × 10-6). Atmospheric stability periods led to an increase in indoor and outdoor pollutant levels. However, the highest I/O ratios were found during atmospheric instability, especially for eBC (an average of 1.2). This might be related to rapid changes in the outdoor air concentrations induced by meteorology. Significant variations were observed in indoor PM10 concentrations during classroom occupancy (up to 230 µg m-3) vs. non-occupancy (up to 19 µg m-3) days, finding levels higher than outdoor ones. This was attributed to the scholarly activities in the classroom. Conversely, PNC and eBC concentrations only increased when the windows of the classroom were open. These findings have helped to establish practical recommendations and measures for improving the IAQ in this school and those of similar characteristics.

Anthropic-Induced Variability of Greenhouse Gasses and Aerosols at the WMO/GAW Coastal Site of Lamezia Terme (Calabria, Southern Italy): Towards a New Method to Assess the Weekly Distribution of Gathered Data

The key to a sustainable future is the reduction in humankind’s impact on natural systems via the development of new technologies and the improvement in source apportionment. Although days, years and seasons are arbitrarily set, their mechanisms are based on natural cycles driven by Earth’s orbital periods. This is not the case for weeks, which are a pure anthropic category and are known from the literature to influence emission cycles and atmospheric chemistry. For the first time since it started data gathering operations, CO (carbon monoxide), CO2 (carbon dioxide), CH4 (methane) and eBC (equivalent black carbon) values detected by the Lamezia Terme WMO/GAW station in Calabria, Southern Italy, have been evaluated via a two-pronged approach accounting for weekly variations in absolute concentrations, as well as the number of hourly averages exceeding select thresholds. The analyses were performed on seven continuous years of measurements from 2016 to 2022. The results demonstrate that the analyzed GHGs (greenhouse gasses) and aerosols respond differently to weekly cycles throughout the seasons, and these findings provide completely new insights into source apportionment characterization. Moreover, the results have been combined into a new parameter: the hereby defined WDWO (Weighed Distribution of Weekly Outbreaks) normalizes weekly trends in CO, CO2, CH4 and eBC on an absolute scale, with the scope of providing regulators and researchers alike with a new tool meant to better evaluate anthropogenic pollution and mitigate its effects on the environment and human health.

Analysis of the possibilities to increase abrasion resistance of welded joints of Hardox Extreme steel

This paper presents a heat treatment process designed to enhance the abrasion resistance of welded joints of Hardox Extreme steel, which is known for its high hardness (>600 HBW) and tensile strength (>2000 MPa). Despite these properties, the steel's weldability, characterized by a Carbon Equivalent Value (CEV) of 0.70, limits its use in applications like mining machinery where welding is essential. The key challenge in welding martensitic boron steels, such as Hardox Extreme, is the reduction in hardness and abrasion resistance in the heat-affected zone, along with cold cracking due to increased hardenability. This study investigates the abrasion resistance and microstructural properties of welded joints made with submerged arc welding (SAW) under different heat treatment conditions. The developed process achieved a uniform tempered martensite microstructure across all welded zones, increased hardness to over 550 HV in the weld material zone and improved the relative abrasion resistance by 25 % compared to the as-welded state.

Black carbon and particle lung-deposited surface area in residential wood combustion emissions: Effects of an electrostatic precipitator and photochemical aging

Residential wood combustion (RWC) remains a significant global source of particulate matter (PM) emissions with adverse impacts on regional air quality, climate, and human health. The lung-deposited surface area (LDSA) and equivalent black carbon (eBC) concentrations have emerged as important metrics to assess particulate pollution. In this study we estimated combustion phase-dependent emission factors of LDSA for alveolar, tracheobronchial, and head-airway regions of human lungs and explored the relationships between eBC and LDSA in fresh and photochemically aged RWC emissions. Photochemical aging was simulated in an oxidative flow reactor at OH• exposures equivalent to 1.4 or 3.4 days in the atmosphere. Further, the efficiency of a small-scale electrostatic precipitator (ESP) for reducing LDSA and eBC from the wood stove was determined. For fresh emission eBC correlated extremely well with LDSA, but the correlation decreased after aging. Soot-dominated flaming phase showed the highest eBC dependency of LDSA whereas for ignition and char burning phases non-BC particles contributed strongly the LDSA. Deposition to the alveolar region contributed around 60 % of the total lung-deposition. The ESP was found as an effective method to mitigate particulate mass, LDSA, as well as eBC emissions from wood stoves, as they were reduced on average by 72%, 71%, and 69%, respectively. The reduction efficiencies, however, consistently dropped over the span of an experiment, especially for eBC. Further, the ESP was found to increase the sub-30 nm ultrafine particle number emissions, with implications for LDSA. The results of this study can be used for assessing the contribution of RWC to LDSA concentrations in ambient air.