Carbon Loading Research Articles

High-resolution multi-parameter monitoring of microbial water quality and particles at two alpine karst springs as a basis for an early-warning system

Karst aquifers are important resources for drinking water supply and are very vulnerable to contamination. Microbial concentrations at karst springs, in particular, often vary quickly over a short period of time. In this study, the response of microbial water quality and particle-size distribution of two alpine karst springs to rainfall events was investigated to test and validate parameters that can be used as early-warning systems for fecal contamination. At both investigated karst springs, total organic carbon, particle-size distribution (especially small particle fractions), and particle load show a good correlation to the fecal indicator bacteria E. coli and can therefore be used as a real-time indicator of fecal contamination at the investigated springs. In addition to conventional bacterial determination methods, the β-D-glucuronidase activity, which can be measured in near real-time, was used as a novel indicator parameter for fecal contamination. At the event scale, the β-D-glucuronidase (GLUC) activity shows a good correlation to E. coli and can be used as an additional real-time indicator of fecal contamination. For the studied springs, when they show two peaks in turbidity and small particles, these two parameters are suitable for an early warning system because the bacterial contamination occurs during the secondary peak of these parameters. These results highlight the vulnerability of karst aquifers and demonstrate the applicability of advanced measurement techniques in detecting fecal contamination in real-time, which is especially important given the time-consuming nature of conventional bacterial detection methods.

Dynamic modeling and coupling characteristics analysis of biomass power plant integrated with carbon capture process

Biomass direct-fired circulating fluidized bed boiler has distinguished advantages of strong fuel adaptability, high combustion efficiency and low NOX emission, thus has been regarded as one of the important pathways for biomass utilization. Retrofitting the biomass direct-fired circulating fluidized bed boiler power plant (BCFBP) with carbon capture can strongly support the goal of carbon neutrality, because negative CO2 emission is achieved during the power generation. Nevertheless, the biomass direct-fired circulating fluidized bed boiler is sensitive to the combustion condition, high in operating costs, slow in dynamic response and poor in regulating capability. The integration of carbon capture may pose significant changes on the operating safety, efficiency and flexibility. A comprehensive analysis is thus required to understand the interactions between the BCFBP and carbon capture under various operating conditions. To this end, this paper develops a plant-wide dynamic model for a 130 ton/h BCFBP integrated with solvent-based post-combustion carbon capture (PCC) system. Multi-stage models of biomass combustion, steam generation and steam turbine-feedwater heater systems are developed to represent the dynamic interactions among biomass, heat, electricity and carbon, so that the impacts of BCFBP operation on the PCC process can be evaluated. Detailed BCFBP-PCC connecting system model are also developed to reflect the dynamic changes of steam/water flowrate, pressure and temperature in the steam turbine system caused by the integration of PCC. The developed model is then used to analyze the system interactions, operating costs, negative carbon capability and load ramping flexibility of the integrated BCFBP-PCC. Results show that the integration of PCC 1) causes significant impacts on the water/steam parameters of the steam turbine-feedwater heaters behind the reboiler steam extraction point; 2) reduces the power output of BCFBP by 26.12 % under 95 % CO2 capture level condition; 3) expands the power output variation range of the BCFBP from 22.3 to 36.6 MWe and provides the negative CO2 emission capacity from 2.2 to 6.9 kg CO2/s; 4) offers a feasible way to improve the power ramping performance through flexible distribution of the water/steam in the steam turbine-feedwater heater system. This paper provides specific guidance for the design, retrofit and operation of the BCFBP-PCC plant.

Adsorptive Removal of Methylene Blue Dye from Aqueous Solutions by Polyvinyl Alcohol/Activated Carbon Nanocomposite Hydrogels

ABSTRACT Polyvinyl alcohol/activated carbon (PVA/AC) nanocomposite hydrogels were prepared using a cyclic freezing-thawing process and successfully used to eliminate methylene blue dye from aqueous media. Characterization of the produced adsorbents was performed using Fourier transform infrared spectroscopy, X-ray diffraction, dynamic light scattering, field emission scanning electron microscopy, Brunauer-Emmett-Teller analysis and gel fraction tests. The swelling abilities of the adsorbents and also the methylene blue diffusion coefficients were determined in acidic, neutral and alkaline media. The contributions of four main factors, including the pH, loading level of activated carbon, initial concentration of methylene blue and temperature on the removal of methylene blue were investigated using the Taguchi method. The results revealed that by increasing the loading level of activated carbon in the adsorbent, the gel fraction was increased while the swelling ratio and methylene blue diffusion coefficient decreased. Meanwhile, by increasing the pH and temperature, the swelling ratio and methylene blue diffusion coefficient increased. The adsorption data showed that the initial concentration of methylene blue had little impact on the adsorption process, while the pH and activated carbon loading level were the most influential factors in the adsorption process. Additionally, the isotherm and kinetics studies demonstrated that the Langmuir isotherm model and the Webber-Morris kinetic model described appropriate fits to the adsorption process data.

Application and evaluation of SWAT-C model to predict TOC loading in the Hwangryong River Watershed

Objectives : This study aims to assess the applicability of the SWAT-C water quality model recently developed to predict in-stream Total Organic Carbon (TOC) in a watershed within South Korea.Methods : The SWAT-C model was tested in the Hwangryong River Watershed. SWAT-C is an advanced version of Soil and Water Assessment Tool (SWAT) to simulate carbon cycling at the watershed scale. The model was simulated for 11 years (2010-2020) consisting of 2-year warm-up (2010-2011), 6-year calibration (2012-2017), and 3-year validation (2018-2020) periods. SWAT-C was calibrated and validated against monthly streamflow and TOC loads. The model performance was evaluated using NSE (Nash-Sutcliffe efficiency), KGE (Kling-Gupta efficiency), and PBIAS (percent bias) Simulated Dissolve Organic Carbon (DOC) and Particulate Organic Carbon (POC) loads were also presented to see the major caron type loaded to the downstream.Results and Discussion : The calibration results showed that SWAT-C could depict streamflow and TOC loads with acceptance model performances (NSE > 0.5, KGE > 0.5 and PBIAS =< 25%). Especially, the seasonal variations of TOC loads were well simulated by SWAT-C. The TOC load was predicted to increase in the summer season with high precipitation and slightly lower in the other seasons. This seasonal pattern is likely caused by frequent heavy rainfall events in summer.Conclusion : This study demonstrated that SWAT-C model is applicable in South Korea with sufficient prediction accuracy. Thus, SWAT-C would serve as an efficient tool to monitor TOC loads in South Korea.

Atmospheric Black Carbon Loadings and Sources over Eastern Sub-Saharan Africa Are Governed by the Regional Savanna Fires.

Vast black carbon (BC) emissions from sub-Saharan Africa are perceived to warm the regional climate, impact rainfall patterns, and impair human respiratory health. However, the magnitudes of these perturbations are ill-constrained, largely due to limited ground-based observations and uncertainties in emissions from different sources. This paper reports multiyear concentrations of BC and other key PM2.5 aerosol constituents from the Rwanda Climate Observatory, serving as a regional receptor site. We find a strong seasonal cycle for all investigated chemical species, where the maxima coincide with large-scale upwind savanna fires. BC concentrations show notable interannual variability, with no clear long-term trend. The Δ14C and δ13C signatures of BC unambiguously show highly elevated biomass burning contributions, up to 93 ± 3%, with a clear and strong savanna burning imprint. We further observe a near-equal contribution from C3 and C4 plants, irrespective of air mass source region or season. In addition, the study provides improved relative emission factors of key aerosol components, organic carbon (OC), K+, and NO3-, in savanna-fires-influenced background atmosphere. Altogether, we report quantitative source constraints on Eastern Africa BC emissions, with implications for parameterization of satellite fire and bottom-up emission inventories as well as regional climate and chemical transport modeling.

Impact of nuclear and renewable energy sources on environment quality: Testing the EKC and LCC hypotheses for South Korea

This study investigates the impacts of nuclear energy consumption on environmental quality from a different perspective by focusing on carbon dioxide (CO2) emissions, ecological footprint, and load capacity factor. In this context, the South Korea case, which is a leading country producing and consuming nuclear energy, is investigated by considering also economic growth, and the 1997 Asian crisis from 1977 to 2018. To this end, the study employs the autoregressive distributed lag (ARDL) approach. Different from previous literature, this study proposes a load capacity curve (LCC) and tests the LCC and environmental Kuznets curve (EKC) hypotheses simultaneously. The analysis results reveal that (i) the LCC and EKC hypotheses are valid in South Korea; (ii) nuclear energy has an improving effect on the environmental quality; (iii) renewable energy does not have a significant long-term impact on the environment; (iv) the 1997 Asian crisis had an increasing effect on the load capacity factor; (v) South Korea has not yet reached the turning point, identified as $55,411, where per capita income improves environmental quality. Overall, the results show the validity of the LCC and EKC hypotheses and prove the positive contribution of nuclear energy to South Korea's green development strategies.

Facet Impact of CuMn2O4 Spinel Nanocatalysts on Enhancement of the Oxygen Reduction Reaction in Alkaline Media

Surface-structure engineering represents an attractive strategy to optimize the energy conversion performance of nanocatalysts using their deliberately controlled exposed facets. To further exploit the potential of non-Pt-group metal-based spinel catalysts for the alkaline oxygen reduction reaction (ORR), a cathodic fuel cell reaction, we hereby report a strategy of ORR improvement by controlling the crystallographic facets of ultra-small CuMn2O4 spinel nanocatalysts through a developed colloidal synthesis approach. The synthesis of CuMn2O4 nanocrystals with morphological control relies on the design and selection of the Cu/Mn precursors with striking discrepancies in reaction kinetics. Following carbon loading and an annealing post-treatment of the as-synthesized nanocatalysts, the exclusively {101} facet-exposed CuMn2O4 spinel nano-octahedra exhibit improved electrocatalytic activity toward the ORR in 1 M KOH, when compared to their spherical counterparts, exhibiting a mass activity (MA) of 37.6 A/g at 0.85 V. After 10,000 cycles of the ORR durability test, the nano-octahedra still retain an MA of 24.5 A/g, which is twice that of the CuMn2O4 spinel nanospheres. Structural characterizations after durability testing indicate that the MA decay is likely associated with a decrease in the Mn3+ fraction and the emergence of Cu+ on CuMn2O4 nano-octahedral surfaces. As a paradigm, this synthesis approach could be extended to other Mn-based spinel nanocatalysts with precise shape control, enabling us to understand and establish the relationship between the surface lattice/valence state and electrocatalytic properties.

Cobalt and Nickel Free Disorder Rock Salt Cathodes – Recent Developments

Disordered Li-excess rock salt (DRX) cathodes are a promising class of high capacity (and voltage) cathodes for next-generation Li-ion batteries. Compared to conventional Li-ion cathodes which are generally restricted to Co/Ni-based compositions with specific cation ordering, DRX materials have a wide compositional design space based on earth abundant metals such as Mn, Ti, Mo, Al, Zr, V, and Nb. Furthermore, Li-rich oxyfluoride DRX cathodes have demonstrated specific energies up to 1,000 Wh/kg which exceeds that of state-of-the-art layered LiNixMnyCo1-x-yO2 (NMC) cathodes (~700 Wh/kg). Despite such scientific advancements, widespread adoption of DRX cathodes has been hindered by several technical challenges. First, most of the high fluorine content DRX compositions are synthesized using mechano-chemical synthesis that has inherent limitation in scalability and maintaining a uniform particle-size and morphology. Further, DRX compositions have about 3-4 order lower electronic conductivity compared to layered cathodes requiring a high carbon loading in the electrode (up to 25%) compromising energy density. The focus of this talk will be on developing alternate synthesis method for Li-Mn rich DRX compositions. Specifically solid-state and sol-gel synthesis methods to produce DRX cathodes with the nominal composition Li1.2Mn0.4+xTi0.4-xO2-xFx (x = 0-0.3). Detailed advanced characterization (i.e., neutron total scattering and electron microscopy) and modelling efforts (i.e., Reverse Monte Carlo simulations) to understand how SRO impacts cathode performance will be presented. Different choice of precursors based on thermodynamic and kinetic consideration that minimizes formation of LiF impurity phases will be proposed.AcknowledgmentThis work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technologies Office, under the Applied Battery Materials Program, of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725

Nanocomposite Co-catalysts, based on smectite and biowaste-derived carbon, as peroxymonosulfate activators in degradation of tartrazine

Chitosan (Ch)-derived from biowaste along with smectite, an abundant clay mineral, were used in a low-cost and eco-friendly synthesis of a new type of catalyst. Nanocomposite catalysts constituted of Co supported on smectite with chitosan-derived carbon loading were obtained using an impregnation‑carbonization procedure and denoted as Co/cCh-S-T (T stands for applied carbonization temperature). The carbonization was performed in the temperature range from 400 °C to 700 °C in the flow of N2 providing inert atmosphere. The temperature of 500 °C was found to be the most suitable for catalyst synthesis regarding catalytic performance in a peroxymonosulfate activated degradation of tartrazine. The incorporation of carbonized chitosan structure within the interlamellar space of the smectite was confirmed using X-ray powder diffraction. The high-resolution transmission electron microscopy confirmed a layered structure of nanocomposites characteristic for smectite, as well as the presence of small spherical cobalt containing nanoformations (confirmed by energy dispersive X-ray spectroscopy) well dispersed within structure. The existance of cobalt in the CoII and CoIII oxidation state was proven by X-ray photoelectron spectroscopy. The Co/cCh-S-500 catalyst was proven to be stable and efficient after 5 consecutive cycles. This work showed that nanocomposite Co-catalysts, based on smectite and biowaste-derived carbon, as peroxymonosulfate activators exhibited a very promising performance in the degradation of water pollutants.

Benefit analysis and preliminary decision-making of electrical and thermal energy storage in the regional integrated energy system

The ambitious goal of decarbonization has promoted regional integrated energy system (RIES), which enables interaction between energy consumption and supply sectors with different characteristics to improve energy application efficiency. Compared with single energy storage, multiple energy storage (MES) may have the potential to provide better flexibility and lower costs, but the necessity of applying and the preliminary decision-making principles have not been very clear to users and investors. To solve this problem, this study based on the typical RIES framework on the demand-side, firstly proposes multi-dimensional evaluation indexes from the aspects of renewable energy consumption, carbon emission reduction, load shifting and economic property; then, taking a commercial area as a case, develop the optimal operation strategy of the minimum total daily cost to analyze the operation and synergistic benefits under four scenarios; influencing factors such as energy storage capacity, load demand and region types are considered though sensitivity analysis; finally, suggestions for the preliminary decision-making of MES are given. The results show that the combination of electricity and thermal energy storage can realize the complementary advantages of single energy storage technology, making the contribution of different kinds of energy storage benefits more balanced on the basis of reducing the total cost, which significantly improves the flexibility of the energy system; the electricity-thermal energy storage has obvious advantages in the four functional areas involved herein; however, as the storage capacity increases to the saturation value, the marginal effect appears, and the corresponding total benefits tend to stabilize gradually. The preliminary decision-making of applying energy storage is carried out according to the external and internal levels, respectively according to the control requirements of energy storage investment cost, the allocation of renewable energy in the target area, as well as the regional energy consumption structure and specific needs. This principle can provide a reasonable basis for decision-makers and promote the application and development of multiple energy storage.

Hysteresis analysis reveals dissolved carbon concentration – discharge relationships during and between storm events

The dissolved carbon concentration, which is responsible for aquatic ecosystem productivity and water quality, is tightly coupled with hydrological processes. Excess dissolved carbon may exacerbate eutrophication and hypoxia in aquatic ecosystems and lead to deterioration of water quality. Storm events dominate the dynamics of dissolved carbon concentrations, and this nonlinear behavior exhibits significant time scale dependence. Here, we identified inter- and intra-event variability in the dissolved carbon concentration–discharge (C–Q) relationship in an agriculture-intensive catchment. The driving factors of C–Q hysteresis patterns for dissolved inorganic carbon (DIC) and organic carbon (DOC) were quantified by redundancy analysis combined with hierarchical partitioning. At the inter-event scale, DIC exhibited mainly clockwise hysteresis, indicating an exhaustible, proximal source (e.g., groundwater). However, DOC hysteresis was generally counter-clockwise, indicating distal and plentiful sources (e.g., soil water) in the agricultural catchment. Hierarchical partitioning showed that total rainfall, peak discharge and flood intensity explained 28.38% of the total variation in C–Q hysteresis for DIC and 39.87% for DOC at the inter-event scale. At the intra-event scale, time series analysis of dissolved carbon concentration and discharge indicated the interconversion of supply limitation to transport limitation, which depends on the activation of the specific DIC or DOC source zones. These findings provide significant insights into understanding the dynamics of dissolved carbon during storm periods and are important for targeted watershed management practices aimed at reducing carbon loading to surface waters.

High frequency UV–Vis sensors estimate error in riverine dissolved organic carbon load estimates from grab sampling

High frequency ultraviolet – visible (UV–VIS) sensors offer a way of improving dissolved organic carbon (DOC) load estimates in rivers as they can be calibrated to DOC concentration. This is an improvement on periodic grab sampling, or the use of pumped sampling systems which store samples in-field before collection. We hypothesised that the move to high frequency measurements would increase the load estimate based on grab sampling due to systemic under-sampling of high flows. To test our hypotheses, we calibrated two sensors in contrasting catchments (Exe and Bow Brook, UK) against weekly grab sampled DOC measurements and then created an hourly time series of DOC for the two sites. Taking this measurement as a ‘true’ value of DOC load, we simulated 1,000 grab sampling campaigns at weekly, fortnightly and monthly frequency to understand the likely distribution of load and error estimates. We also performed an analysis of daily grab samples collected using a pumped storage sampling system with weekly collection. Our results show that: a) grab sampling systemically underestimates DOC loads and gives positively skewed distributions of results, b) this under-estimation and positive skew decreases with increasing sampling frequency, c) commonly used estimates of error in the load value are also systemically lowered by the oversampling of low, stable flows due to their dependence on the variance in the flow-weighted mean concentration, and d) that pumped storage systems may lead to under-estimation of DOC and over estimation of specific ultra-violet absorbance (SUVA), a proxy for aromaticity, due to biodegradation during storage.

Effects of soil trace metals, organic carbon load and physicochemical stressors on active oxygen species metabolism in Scylla serrata sampled along the Bay of Bengal in Odisha state, India

Studies on the synergetic effects of soil and water parameters on Oxidative Stress (OS) physiology systems of the edible mud crab Scylla serrata sampled from different parts of East India are unknown. This study aimed to evaluate the effects of soil Ca, Mg, and organic carbon load and water physicochemical stressors induced spatio-temporal variation of tissue-specific OS and antioxidant parameters in S. serrata along the Bay of Bengal in Odisha. Spectrophotometric or Fourier-transform infrared spectroscopy methods were employed to measure the OS physiology and physicochemical parameters. Pedological and physicochemical factors of water were varied significantly in summer (38–42°C), rainy (25–35°C), and winter (12–20°C) seasons. Activities of antioxidant enzymes (AE) such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and the level of lipid peroxidation (LPx) were found to be higher in hepatopancreas as compared to other tissues irrespective of seasonal variation. Considering the impact of dry seasons, an average of 13.23% enhanced activities of AE were noticed in different tissues of S. serrata in response to temperature, salinity, organic carbon, Mg, and Ca load of sampling sites. However, about 11.26% decrease in the activities of AEs, including GR and GST in most of the tissues were recorded, along with a 21% alleviated level of LPx observed in the rainy season compared to other seasons. Among three coastal zones of the Bay of Bengal, the AEs in crabs sampled from Chandipur were elevated by 5.43% in winter, whereas a 7.05% enhanced level of LPx was found in summer compared to crabs sampled from Chilika and Jagatsinghpur. Overall, the levels of LPx, total antioxidant, and activities of AEs (CAT, GST, GPx, and GR) have shown a positive correlation, whereas ascorbic acid and GSH negatively correlate with habitat water pH, temperature, and salinity of soil and water. The results can be used for ecotoxic and environmental biomonitoring purposes using crabs as model organisms across tropical coastal regions.

Chain-like carbon nano-onions from candle flame combustion as a high-performance cathode for aluminum-air batteries

A positive air electrode capable of a high‑oxygen reduction reaction (ORR) from chain-like carbon nano-onions (CLCNOs) was synthesized directly onto the surface of nickel foam using candle flame combustion. The 50 s synthesis positive air electrode with a carbon loading of 0.49 mgcm−2 provides higher ORR catalytic capability than that of other time synthesizers in natural pH electrolytes. Increasing the cathode-to-anode ratio increases the cell voltage from 0.41 to 0.53 V, causing the specific capacity to reach 1108 mAhg−1. In addition, a positive air electrode can work continuously for 14 days, even after repeated use and replacement of new aluminum anodes several times.

Spatiotemporal variations of dissolved CH4 concentrations and fluxes from typical freshwater types in an agricultural irrigation watershed in Eastern China

Inland freshwater ecosystems are of increasing concerns in global methane (CH4) budget in the atmosphere. Agricultural irrigation watersheds are a potential CH4 emission hotspot owing to the anthropogenic carbon and nutrients loading. However, large-scale spatial variations of CH4 concentrations and fluxes in agricultural catchments remain poorly understood, constraining an accurate regional estimate of CH4 budgets. Here, we examined the spatiotemporal variations of dissolved CH4 concentrations and fluxes from typical freshwater types (ditch, reservoir and river) within an agricultural irrigation watershed from Hongze catchment, which is subjected to intensive agricultural and rural activities in Eastern China. The dissolved CH4 concentrations and fluxes showed similar temporal variations among the three freshwater types, with the highest rates in summer and the lowest rates in winter. The total CH4 emission from this agricultural irrigation watershed was estimated to be 0.002 Gg CH4 yr−1, with annual mean CH4 concentration and flux of 0.12 μmol L−1 and 0.58 mg m−2 d−1, respectively. Diffusive CH4 fluxes varied in samples taken from different freshwater types, the annual mean CH4 fluxes for ditch, reservoir and river were 0.31 ± 0.06, 0.71 ± 0.13 and 0.72 ± 0.25 mg m−2 d−1, respectively. Among three freshwater types, the CH4 fluxes were the lowest in ditch, which was associated with the lowest responses of CH4 fluxes to water dissolved oxygen (DO), nitrate nitrogen (NO3−-N) and sediment dissolved organic carbon (DOC) concentrations in ditch. In addition, water velocity and wind speed were significantly lower in ditch than in reservoir and river, suggesting that they also played important roles in explaining the spatial variability of dissolved CH4 concentrations and fluxes. These results highlighted a need for more field measurements with wider spatial coverage and finer frequency, which would further improve the reliability of flux estimates for assessing the contribution of agricultural watersheds to the regional and global CH4 budgets.

Enhanced nitrogen and carbon removal in natural seawater by electrochemical enrichment in a bioelectrochemical reactor

Municipal and industrial wastewater discharges in coastal and marine environments are of major concern due to their high carbon and nitrogen loads and the resulted phenomenon of eutrophication. Bioelectrochemical reactors (BERs) for simultaneous nitrogen and carbon removal have gained attention owing to their cost efficiency and versatility, as well as the possibility of electrochemical enrich specific groups. This study presented a scalable two-chamber BERs using graphite granules as electrode material. BERs were inoculated and operated for 37 days using natural seawater with high concentrations of ammonium and acetate. The BERs demonstrated a maximum current density of 0.9 A m−3 and removal rates of 7.5 mg NH4+-N L−1 d−1 and 99.5 mg L−1 d−1 for total organic carbon (TOC). Removals observed for NH4+-N and TOC were 96.2% and 68.7%, respectively. The results of nutrient removal (i.e., ammonium, nitrate, nitrite and TOC) and microbial characterization (i.e., next-generation sequencing of the 16S rRNA gene and fluorescence in situ hybridization) showed that BERs operated with a poised cathode at −260 mV (vs. Ag/AgCl) significantly enriched nitrifying microorganisms in the anode and denitrifying microorganisms and planctomycetes in the cathode. Interestingly, the electrochemical enrichment did not increase the total number of microorganisms in the formed biofilms but controlled their composition. Thus, this work shows the first successful attempt to electrochemically enrich marine nitrifying and denitrifying microorganisms and presents a technique to accelerate the start-up process of BERs to remove dissolved inorganic nitrogen and total organic carbon from seawater.

Evaluation of ozone removal devices applied in ventilation systems

Applying ozone removal devices in ventilation systems is an effective way to reduce building occupant exposure to ozone. However, little is known about the performance of commercially-available ozone removal devices under realistic usage conditions, especially for technologies that have recently emerged for general ventilation such as ultraviolet photocatalytic oxidation (UV–PCO) and catalysis (without UV). A total of 14 ozone removal devices that are representative of products on the market were selected: 11 activated carbon filters, 2 UV-PCO devices, and 1 catalyst filter without UV. We tested these devices with an “ozone stress test” by exposing them to 70 ppb, 107 ppb, and 500 ppb of ozone at 25 °C, 50% RH, and 2.5 m/s face velocity. The device performance was evaluated by the average efficiency at each ozone level, degradation rate at 500 ppb, pressure drop, and a quality factor that combines efficiency and pressure drop. Results show a wide range of single-pass removal efficiency from 3% to 93% at 70 ppb. All devices degraded at a slow rate; at 500 ppb, most devices degraded at 1.5%/h relative to their efficiency at the beginning of this period. The catalyst (no UV) and three 12″ activated carbon devices achieved high efficiency at the least cost of pressure drop. The loading and source of carbon had a significant impact on the efficiency of activated carbon filters. A two-fold increase in carbon loading led to nearly a two-fold higher single-pass removal efficiency. Coal-based carbon degraded 20 times faster than coconut shell-based carbon.

Determinants of carbon load in airway macrophages in pregnant women

BACKGROUND AND AIM: The airway macrophages carbon loading (AMCL) has been suggested to be a biomarker of the long-term exposure to air pollution; however, to date no study has characterized AMCL for the pregnancy period. Therefore, this study aimed to assess the determinants of AMCL during pregnancy in Iran, a middle-income country. METHODS: This study was based on a sample of 234 pregnant women with term and normal vaginal delivery who were residing in Sabzevar, Iran (2019). Image analysis was applied to calculate the carbon area (µm2) in airway macrophages as an indicator of AMCL. Measuring the AMCL was performed by two independent investigators and checked by third investigator to reduce the AMCL measurement bias. We characterized 35 potential determinants of personal exposure to air pollution for each participant, including six personal, nine indoor, and 20 home-outdoor factors. We applied Deletion/Substitution/Addition algorithm to identify the most relevant determinants that could predict AMCL levels. RESULTS: The median (IQR) of AMCL level was 0.12 (0.30) µm2 with a successful sputum induction in 82.9% (194) of participants. Ambient residential PM2.5 levels were positively associated with higher AMCL levels. On the other hand, increased residential distance to the traffic lights, squares and ring-roads, the duration of opening window per day, and opening window during cooking were inversely associated with AMCL levels. CONCLUSIONS: This study is the first to characterize AMCL during pregnancy. Moreover, this is one of the largest reported studies on characterization of AMCL levels. Furthermore, this is the first study to explore the personal, indoor and outdoor determinates of personal exposure to air pollution in pregnant women in an LMIC. Our findings provide novel insights on the different personal, indoor, and outdoor determinants of personal exposure to air pollution during pregnancy in a middle-income country. KEYWORDS: Air pollution, Pregnancy, Biomarker, Lung

Effects of prenatal exposure to air pollution on placental molecular hallmarks and black carbon load

Effects of prenatal exposure to air pollution on placental molecular hallmarks and black carbon load

COVID-19 disease severity in hospitalized patients is associated with short- and long-term exposure to air pollutants

Background and Aim Existing evidence suggests that exposure to air pollutants (AP) such as particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2) and black carbon (BC) is associated with COVID-19 infection rates and mortality. We investigated whether exposure to AP was associated with COVID-19 disease severity in a cohort of hospitalised COVID-19 patients. Methods 329 COVID-19 patients were recruited at the time of admission to hospital. Clinical parameters and outcomes were collected from medical records, including the duration of stay, the early-warning score (EWS), oxygen saturation, and PaO2/FiO2 ratios. Daily exposure levels for PM2.5, PM10, NO2 and BC were modelled using a high-resolution spatiotemporal model. Black carbon particles in blood were quantified using femtosecond pulsed laser illumination. Associations between exposure to air pollutants and clinical outcomes were modelled using multiple regression models while adjusting for potential confounders. Results The duration of stay increased by 1 to 6 days for an interquartile range (IQR) increase in average exposure to AP in the week before admission (PM2.5: +5.2 days, NO2: +5.8 days). Similarly, an IQR increase in long-term exposure (to AP was associated with increased duration of stay (PM2.5: +2.8 days, NO2: +3.2 days, BC: +2.8 days). Furthermore, an increase in PM2.5 exposure 1 week before admission was associated with higher EWS (+0.40). Finally, IQR increases in long-term exposure to PM10, BC and NO2 as well as blood black carbon load were associated with odds of admission to the intensive care unit (OR: +1.32, +2.12, +2.46 and +1.19 respectively). Conclusion Exposure to AP was associated with duration of stay and EWS scores at the time of admission, which implies a potential link between AP exposure and COVID-19 disease severity, and a significant influence of AP exposure on the pressure on medical care systems during the COVID-19 pandemic.