Carbon dioxide (CO2) is the main anthropogenic greenhouse gas contributing to global warming, causing tremendous impacts on the global ecosystem. Fossil fuel combustion is the main anthropogenic ...source of CO2 emissions. Biochar, a porous carbonaceous material produced through the thermochemical conversion of organic materials in oxygen-depleted conditions, is emerging as a cost-effective green sorbent to maintain environmental quality by capturing CO2. Currently, the modification of biochar using different physico-chemical processes, as well as the synthesis of biochar composites to enhance the contaminant sorption capacity, has drawn significant interest from the scientific community, which could also be used for capturing CO2. This review summarizes and evaluates the potential of using pristine and engineered biochar as CO2 capturing media, as well as the factors influencing the CO2 adsorption capacity of biochar and issues related to the synthesis of biochar-based CO2 adsorbents. The CO2 adsorption capacity of biochar is greatly governed by physico-chemical properties of biochar such as specific surface area, microporosity, aromaticity, hydrophobicity and the presence of basic functional groups which are influenced by feedstock type and production conditions of biochar. Micropore area (R2 = 0.9032, n = 32) and micropore volume (R2 = 0.8793, n = 32) showed a significant positive relationship with CO2 adsorption capacity of biochar. These properties of biochar are closely related to the type of feedstock and the thermochemical conditions of biochar production. Engineered biochar significantly increases CO2 adsorption capacity of pristine biochar due to modification of surface properties. Despite the progress in biochar development, further studies should be conducted to develop cost-effective, sustainable biochar-based composites for use in large-scale CO2 capture.
•Engineered biochar possesses significantly high CO2 adsorption capacity.•Basic functional groups and hetero atoms are important for high CO2 adsorption capacities.•New technologies are needed for regenerating and reusing captured CO2.
As an important part of the anthropogenic aerosol, Black Carbon (BC) aerosols in the atmospheric environment have strong impacts on climate change. Recently, most remote sensing studies on aerosol ...components detection are limited to the inversion of aerosol optical properties, integration of chemistry models or in situ observations. In this paper, an algorithm based on Effective Medium Approximations (EMA) and statistically optimized aerosol inversion algorithm was integrated for retrieving the surface mass concentration of BC aerosols from satellite signals. The sensitivity analyses for the developed forward model proved that the volume fraction of vertical BC is sensitive to the satellite observations and significantly improved especially over bright surface targets or under polluted atmospheric conditions. By updating the forward model and retrieved parameters of the statistically optimized inversion algorithm, three cases of high aerosol loading days were retrieved from Polarization and Anisotropy of Reflectance for Atmospheric Sciences Coupled with Observations from a LiDAR (PARASOL) measurements, which shows a significant ability of BC aerosol detection. Additionally, the validation and closure studies of BC concentration retrievals also indicates an encouraging consistency with correlation (R) of 0.71, mean bias of 3.55, and root-mean-square error (RMSE) of 3.75 when compared against the in-situ observations over South Asia. The accuracy of the retrievals also demonstrates different trends under different levels of aerosol loadings, which shows a higher accuracy in biomass burning seasons (R = 0.75, RMSE = 4.04, Bias = 3.27) while exaggerates the results in the case of clear conditions (R = 0.47, RMSE = 4.83, Bias = 4.00). Finally, the uncertainties of three assumptions, including proposing uniform vertical profile for BC, neglecting light-absorbing aerosols and using spherical EMA models were discussed in our manuscript. The maximum standard deviations caused by these uncertainties on low BC aerosol volume fractions (fBC < 1%) are 0.8%, 0.35% and 0.2% while these deviations will change to 0.25%, 0.05% and 1.5% respectively under higher BC fractions (fBC > 5%). This conclusion confirmed that the proposed algorithm for BC surface concentration retrieval extends the application of satellite remote sensing in monitoring the extreme biomass burning pollution.
•Satellite based BC surface concentration retrieval algorithm was developed.•Detailed sensitivities of integral forward modules of EMA and RTM were proposed.•Global high aerosol loads cases and closure validation studies of BC were tested.•Detailed uncertainties of expected assumptions in retrieval were analyzed.
Air pollutants such as NO2 and PM2.5 have consistently been linked to mortality, but only few previous studies have addressed associations with long-term exposure to black carbon (BC) and ozone (O3).
...We investigated the association between PM2.5, PM10, BC, NO2, and O3 and mortality in a Danish cohort of 49,564 individuals who were followed up from enrollment in 1993–1997 through 2015. Residential address history from 1979 onwards was combined with air pollution exposure obtained by the state-of-the-art, validated, THOR/AirGIS air pollution modelling system, and information on residential traffic noise exposure, lifestyle and socio-demography.
We observed higher risks of all-cause as well as cardiovascular disease (CVD) mortality with higher long-term exposure to PM2.5, PM10, BC, and NO2. For PM2.5 and CVD mortality, a hazard ratio (HR) of 1.29 (95% CI: 1.13–1.47) per 5 μg/m3 was observed, and correspondingly HRs of 1.16 (95% CI: 1.05–1.27) and 1.11 (95% CI: 1.04–1.17) were observed for BC (per 1 μg/m3) and NO2 (per 10 μg/m3), respectively. Adjustment for noise gave slightly lower estimates for the air pollutants and CVD mortality. Inverse relationships were observed for O3. None of the investigated air pollutants were related to risk of respiratory mortality. Stratified analyses suggested that the elevated risks of CVD and all-cause mortality in relation to long-term PM, NO2 and BC exposure were restricted to males.
This study supports a role of PM, BC, and NO2 in all-cause and CVD mortality independent of road traffic noise exposure.
•Higher exposure to PM2.5, PM10, NO2 and black carbon was associated with mortality.•Associations of air pollutants and CVD mortality were independent of noise exposure.•O3 exposure was not associated with increased mortality risk.
Here we present a long-term, hourly resolution dataset (from January 2014 to April 2015) of secondary inorganic aerosol (SIA) matter, organic matter (OM) and black carbon (BC) as PM2.5 chemical ...components in China. Seasonally differentiated weekly diurnal profiles of major particulate species were investigated in conjunction with potential source contribution function (PSCF) analysis. The average concentration of PM2.5 was 48.3 ± 35.1 μg m−3, in which OM was the major constituent (29.7 ± 13.9%), followed by sulfate (25.1 ± 8.1%), nitrate (18.5 ± 8.3%), ammonium (13.3 ± 3.8%), and other trace species (6.8 ± 4.0%). Interestingly, unlike other PM species, OM concentrations kept very similar level among different seasons, indicating on-road traffic is a stable source of PM2.5. Besides, a persistently strong particulate OM pollution belt was found along the lower reaches of Yangtze River. Significant enhancement of SIA (mainly nitrate) was coincided with high PM2.5 mass loading. Source apportionment were conducted and found the overwhelming dominance of long-range transport of the pollutants from north China. Using a case study, we further integrate Weather Research and Forecasting (WRF) meteorological modeling and lidar observation to better understand the evolution process of a typical pollution episode. Our assessment of the extremely large datasets derived from Shanghai supersite demonstrated the online instrumentation as a robust and credible alternative to filter-based sampling techniques for long-term PM2.5 monitoring and characterization in heavily polluted areas.
•A comprehensive, long-term, hourly resolution measurement of PM2.5 chemical components in China was reported and analyzed.•Particulate organic matter concentrations kept similar level among different seasons.•A main fraction of long-range transport of the pollutants originated from north China.
Raising population, deteriorating environmental conditions and limiting natural resources to handle the key environmental health problems have critically affected human health and the environment. ...Policy makers and planners in Nepal are more concerned today than at any other time in the past about the deterioration of the environmental condition. Therefore, understanding the connection between pollution and human wellbeing is fundamental endeavors to control pollution exposures and secure human wellbeing. This ability is especially critical for countries like Nepal where the issues of environmental pollution have customarily taken a second place to request for economic development. In this study, spatial distribution and sources of 12 heavy metals (HMs) were investigated in surface soils (n = 24) and house dust (n = 24) from four major urban areas of Nepal in order to mark the pollution level. Additionally, a health risk was estimated to establish the link between HMs pollution and human health. Results showed that the median concentration of Ag, Cd, Co, Cr, Cu, Ni, Pb, Sb, Mn and Zn in soil and dust were 2–13 times greater than the background value. The As, Zn, Cu, Cd, and Pb showed a relatively higher spatial variability in soil and dust. Zn was the most abundant metal measured in dust and soil and accounted for 59% and 55% of ∑7HMs, respectively. The HMs in soil and dust were poorly correlated with total organic carbon (TOC) and black carbon (BC), suggesting little or no influence on HMs contamination. Source analysis study indicated the distribution of Cr, Ni, Sb, Ag, Pb, Cu, and Zn in soil and dust are mainly affected by anthropogenic sources, particularly traffic emissions, industrial source, and domestic households materials, while Co, Fe, As, Mn and Cd were from natural sources. The estimated carcinogenic risk (CR) of HMs in soil and dust exceeded the acceptable level of human exposure, recommending significant CR to the local population.
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•Heavy metals concentration in dust was slightly higher than those in soil.•Zn was the most abundant metal measured both in dust and soil.•Majority of metals in both mediums were mainly affected by anthropogenic sources.•Co, Fe, As, Mn and Cd were mainly originated from natural sources.•The average cancer risk exceeded the acceptable level.
The sources of airborne particulate matter (PM10) emissions in Ostrava, Czech Republic, were investigated. Emphasis was placed on their organic carbon (OC) and elemental carbon (EC) contents, and ...their carbon stable isotope composition, δ13C. Emission sources were identified using OC-δ13C and concentration values. To track the extent of long-term deposition, these sources were also identified using the black carbon (BC) δ13C values of soil samples. At all sampling sites, wind flow is predominantly (65–80%) bidirectional in either SW-NE or NE-SW trajectories. Source apportionment along these dominant airflow trajectories was calculated from an isotopic 13C mass balance, and according to differences in the OC content and δ13C values of PM10. Determined emission sources are: (i) combustion of Silesian hard coal (δ13C = −24.5‰); (ii) local Ostrava coal combustion (δ13C = −25.5 to −26‰), automotive emissions (δ13C = −26.5‰), and biogenic particles (δ13C = −28 to −28.5‰). Winter emissions (mean OC concentrations from 12 to 25 μg m−3) originated mostly from coal combustion (80%) in domestic and industrial point sources. Differences were ascribed to automotive emissions. Ostrava is located near the Czech-Polish border, transboundary emissions are transported under a southbound wind flow that transported from 40 to 80% of the collected PM10. Summer emissions were lower (mean OC concentration from 6 to 8 μg m−3). Automotive emissions accounted for up to 40%, whilst biogenic production accounted for 60%. Absence of 13C isotope data of secondary OC (SOC 1.2–1.5 μg m−3) increases uncertainty in our source apportionment in summer; when SOC could comprise >20% of total OC. Contribution of SOC to the winter-measured OC is much lower (5–10%), and has no significant effect on mass balances. The upper soil layer analyses revealed long-term deposition of the same emissions sources. We conclude that the stable δ13C isotope values of OC and EC are useful for discriminating against local sources of PM10 pollution in relatively small urban areas, containing discrete polluting sources. Such a simplified approach can be easily standardized and implemented to manage regulatory compliances in the increasingly commoditized carbon offset market.
Apportionment of sources of PM emissions in Ostrava area represented by the OC concentration under northern wind conditions. The sampled sites are presented on the x axis, and the OC concentrations are on the y axis. Display omitted
•Sources of particulate matter emissions were traced using 13C data of organic and black carbon.•Studied area is the industrial city area with numerous pollution sources.•The apportionment of sources was calculated from the mass balance of organic carbon and 13C.•Deposition of emissions was detected in 13C of black carbon on surface layer of soils.
This study analyzes a multi-year dataset of equivalent black carbon (EBC) concentration collected in 2012–2015 by a 7-wavelengths Aethalometer at Centro Olio Val d’Agri (COVA) in southern Italy, ...which is the largest European oil pre-treatment plant. These data, together with the local air circulation analysis, were used to identify the black carbon (BC) sources in Agri valley, specifically the COVA plant and vehicular traffic. During a limited period of 2012–2013, simultaneous measurements of PM10 concentration were available for comparison with the EBC data, which revealed correlation values of 0.31–0.43 between PM10 and EBC indicating a relevant contribution of BC to particulate matter at the site. On average, EBC/PM10 ratio is 7%, a value equal to that found at an urban-background site in Rome measured during non-rush hours.
Moreover, an ad hoc procedure combining EBC data, Hybrid Single-Particle Lagrangian Integrated Trajectory back-trajectories (HYSPLIT), and satellite fire data enabled detection of days affected by the transport of carbonaceous particles. Both Visible Infrared Imaging Radiometer Suite (VIIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data were used as input for the algorithm, and the corresponding results were compared and discussed. VIIRS showed a better performance in detecting smaller/cooler hotspots especially in cases of flaring, as observed during flaring events at the COVA plant itself.
Application of the procedure suggests that both regional and non-regional biomass burning episodes, which occur mainly during summer, could contribute to the BC load at the site.
The approach applied to the case study of the present work can be useful for estimating the relative contributions of local and remote sources of BC.
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•A four-year data-set of equivalent black carbon at an onshore oil pre-treatment plant.•Oil plant and vehicular traffic as the main black carbon local sources.•A versatile algorithm to infer transboundary sources of black carbon.•Integration of ground-based equivalent black carbon and satellite fire data.•Transboundary biomass burning contribution identification.
The warming effect of equivalent Black Carbon (EBC) aerosols due to their light absorbing nature is a serious environmental concern, particularly, in the eco-sensitive and glaciated Himalayan region. ...Moreover, baseline data on BC is rarely available from most of the glaciated Himalayan region. For the first time, measurements on ambient EBC mass concentration were made at a high altitude site Chirbasa (3600 m, amsl), near Gangotri Glacier in the Indian Himalaya, during the year 2016. The change in the EBC concentration over the year was recorded from 0.01 μg m−3 to 4.62 μg m−3 with a diurnal variability of 0.10 μg m−3 to 1.8 μg m−3. The monthly mean concentration of EBC was found to be minimum (0.089 ± 0.052 μg m−3) in August and maximum (0.840 ± 0.743 μg m−3) in the month of May. The observed seasonal mean concentrations of EBC are less than 0.566 μg m−3 whereas the annual mean is 0.395 ± 0.408 μgm−3 indicating a pristine glacial and absence of locality EBC sources. Further, investigation on the occasional high values extricated that the seasonal cycle of EBC was significantly influenced by the emissions resulting from agriculture burning (in western part of the country), forest fires (along the Himalayan slopes) in summer, and to some extent the contribution from long range transport of pollutants in winter, depending the prevailing meteorological condition.
•First-ever EBC measurements from Gangotri glacier valley are presented.•Significant variations in EBC are recorded in the range of 0.01–4.6 μg m−3.•Burning of forests/agriculture residue are identified as potential EBC sources.•Regional meteorology is found to play a vital role in transporting EBC to glaciers.
Electrochemical oxygen reduction to hydrogen peroxide (H
O
) in acidic media, especially in proton exchange membrane (PEM) electrode assembly reactors, suffers from low selectivity and the lack of ...low-cost catalysts. Here we present a cation-regulated interfacial engineering approach to promote the H
O
selectivity (over 80%) under industrial-relevant generation rates (over 400 mA cm
) in strong acidic media using just carbon black catalyst and a small number of alkali metal cations, representing a 25-fold improvement compared to that without cation additives. Our density functional theory simulation suggests a "shielding effect" of alkali metal cations which squeeze away the catalyst/electrolyte interfacial protons and thus prevent further reduction of generated H
O
to water. A double-PEM solid electrolyte reactor was further developed to realize a continuous, selective (∼90%) and stable (over 500 hours) generation of H
O
via implementing this cation effect for practical applications.
Studies show that fine particulate matter (PM2.5) contributes to childhood obesity. However, evidence on the effects of its constituents on obesity has not been explored.
Using multistage stratified ...cluster sampling, we enrolled 41,439 school-age children (aged 6–17 years) from a representative nationwide survey of 30 provinces in China (mean age ± standard deviation: 12.0 ± 3.3 years). Weight and height were measured using a physician beam scale with a height rod, and covariates were determined using a standard questionnaire. The concentration of PM2.5 chemical constituents was estimated by a chemical transport (GEOS-Chem) model using input satellite data and ground-based observations. The constituents included black carbon, ammonium, nitrate, organic matter, sulfate, and soil dust. Generalized linear models were used to estimate the association between the chemical constituents of PM2.5 and obesity.
A positive association between the constituents of PM2.5 and obesity were observed. Children were more susceptible to black carbon than other species. A 1-μg/m3 increase in black carbon led to a 0.079 (95 % confidence interval CI:0.028, 0.130)-kg/m2 increase in body mass index (BMI). This also increased the odds of being obese and overweight to 1.174 (95 % CI: 1.111, 1.240) and 1.165 (95 % CI: 1.116, 1.216), respectively. Stratified analyses showed that the effects were stronger in girls and older children, as well as in urban and Northeast regions. The effect of the PM2.5 constituents on obese and overweight children from urban areas significantly interacted with that of rural areas.
The PM2.5 constituents were associated with an increased BMI and childhood obesity. Further studies are warranted to validate these results and clarify their potential mechanisms. We suggest focusing on black carbon and Northeast regions.
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•This is the first study found PM2.5 constituents associated with obesity positively.•PM2.5 chemical constituents were associated with higher risk of obesity in children.•Black carbon had the strongest effects on the obesity-related traits.•Girls, older children, and those living in Northeast are more vulnerable.
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