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.
Display omitted
•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.
A direct route to pure peroxideDespite the widespread use of hydrogen peroxide as an oxidant and disinfectant, its commercial synthesis still requires inefficient concentration and purification ...steps. Xia et al. now report an electrochemical approach to synthesizing pure peroxide solutions straight from hydrogen and oxygen. Using a solid-state electrolyte, they avoid contamination of the product solution by extraneous ions. Varying the flow rate of water through the electrochemical cell tunes the final concentration over a range from 0.3% to 20% by weight.Science, this issue p. 226Hydrogen peroxide (H2O2) synthesis generally requires substantial postreaction purification. Here, we report a direct electrosynthesis strategy that delivers separate hydrogen (H2) and oxygen (O2) streams to an anode and cathode separated by a porous solid electrolyte, wherein the electrochemically generated H+ and HO2– recombine to form pure aqueous H2O2 solutions. By optimizing a functionalized carbon black catalyst for two-electron oxygen reduction, we achieved >90% selectivity for pure H2O2 at current densities up to 200 milliamperes per square centimeter, which represents an H2O2 productivity of 3.4 millimoles per square centimeter per hour (3660 moles per kilogram of catalyst per hour). A wide range of concentrations of pure H2O2 solutions up to 20 weight % could be obtained by tuning the water flow rate through the solid electrolyte, and the catalyst retained activity and selectivity for 100 hours.
A palladium phosphide electrocatalyst supported on carbon black (PdP2@CB) shows efficient water splitting in both alkaline and neutral electrolytes. Significantly lower overpotentials are required ...for PdP2@CB (27.5 mV in 0.5 m H2SO4; 35.4 mV in 1 m KOH; 84.6 mV in 1 m PBS) to achieve a HER electrocatalytic current density of 10 mA cm−2 compared to commercial Pt/CB (30.1 mV in 0.5 m H2SO4; 46.6 mV in 1 m KOH; 122.7 mV in 1 m PBS). Moreover, no loss in HER activity is detectable after 5000 potential sweeps. Only 270 mV and 277 mV overpotentials are required to reach a current density of 10 mA cm−2 for PdP2@CB to catalyze OER in 1 m KOH and 1 m PBS electrolytes, which is better OER activity than the benchmark IrO2 electrocatalyst (301 mV and 313 mV to drive a current density of 10 mA cm−2). 1.59 V and 1.72 V are needed for PdP2@CB to achieve stable water splitting catalytic current density of 10 mA cm−2 in 1 m PBS and 50 mA cm−2 in 1 m KOH for 10 h, respectively.
Low‐voltage splitting: A palladium phosphide electrocatalyst supported on carbon black (PdP2@CB) exhibits superior electrocatalytic activity toward water splitting in alkaline and neutral electrolytes. Significantly lower overpotential is required for PdP2@CB to achieve a water splitting electrocatalytic current density of 10 mA cm−2 compared to commercial Pt/CB||IrO2.
•A reproducible BPCA quantification procedure for deep-sea sediments.•Black carbon derived BPCA exhibit a notable prevalence in marine sediments.•Using BPCA isotopes to trace the origin of black ...carbon in marine sediments.•Sedimentary black carbon results from both marine and pyrogenic sources.
Methodologies based on benzene polycarboxylic acids (BPCA) selectively target the polymeric aromatic fraction of black carbon (BC) and are considered adequate to quantify pyrogenic inputs in environmental samples such as soils, lakes, and marine dissolved organic carbon. However, the usefulness of these methodologies to quantify BPCA-derived BC in deep-sea sediments has not been fully evaluated. In this manuscript we describe and validate a procedure to quantify BPCAs in deep oceanic sediments with very low organic carbon content. The resulting analytical procedure has produced reproducible quantitative data for BPCAs over a period of 10 months (coefficient of variation, CV = 6.4 − 6.6%). The stable carbon isotopes (δ13C) of BC_BPCA have been characterized using an LC Isolink™-irMS system with an accuracy better than 0.5‰. The quantitative and isotopic composition of several marine sediments has been characterized to investigate the relative contributions of marine/diagenetic and continental/pyrogenic sources to the BC accumulated in oceanic sediments from different contexts, ranging from upwelling systems to remote oceanic locations. Overall, a significant fraction of the sedimentary BC is of marine origin and should be considered in inventories of pyrogenic materials accumulated in the world oceans. However, the continental/pyrogenic sources can be largely dominant in marine settings with large inputs of pyrogenic materials.
This work documents the extremely high concentrations of fine aerosol particles (PM2.5), equivalent black carbon (eBC) and carbon monoxide (CO) experienced by commuters in one of the world largest ...Bus Rapid Transit (BRT) systems, located in Bogotá, Colombia. A strong relationship between vehicle emissions standard and in-vehicle concentrations was established. Extensive measurements of PM2.5, eBC, and CO were carried out inside the system buses and stations. Measurements were performed during eleven months covering all the system lanes and a significant fraction of the bus fleet and stations. Based on the observed in-bus and in-station concentrations, travel times, and urban ambient levels, the contribution of a typical round trip in the BRT system to the daily inhaled dose was estimated to be 60% for PM2.5, and between 79% and 90% for eBC. The mean PM2.5 dose inhaled by commuters in a typical round trip in the system is 1.2 times the dose a subject would inhale over 24 h exposed to WHO guideline of 25 μgm−3. In 52 out of 180 buses sampled the mean in-cabin concentration of eBC was in excess of 100 μgm−3. Measurements show that mean ratio of in-bus to urban ambient concentration is 8:1 for PM2.5 and 4:1 for CO. These ratios were observed to be much larger when traveling inside the older fraction of the BRT fleet, reaching 11:1 and 7:1 for PM2.5 and CO respectively. These older buses consist exclusively of Euro II and Euro III nominal emission standard vehicles. Average exposure levels inside Euro II and III buses was twice as large as those measured inside vehicles with stricter emission standards, Euro IV or superior. Overall, the measurements suggest that the entrainment of polluted pockets of air to the semi enclosed micro-environments in the system, namely, buses and stations, explains the extreme observed exposure concentrations. Measurements inside an underground bus-station where traffic is restricted to only BRT buses, and on-board a zero emission fully electric BRT bus suggested most of the pollution in the system comes from entrainment of the exhaust of the diesel-powered BRT buses. The significantly lower exposure and inhaled dose of PM2.5, eBC, and CO observed for commuters in newer vehicles suggests that a fleet renewal could have a disproportionately large impact on reducing population exposure to air pollutants. The extent of the reduction in exposure and inhaled dose through fleet renewal is proportional to the gradient of in-bus to urban ambient air pollution levels.
•Concentrations of air pollutants were measured in one of the world largest Bus Rapid Transit Systems (BRT).•Extremely high Black Carbon, PM2.5, and CO concentrations were observed inside buses and stations.•The dose of PM2.5 experienced during a typical round-trip in the BRT system contributes 60% to the daily inhaled dose.•In-cabin concentrations were twice as large for commuters in Euro II or III buses compared to those in Euro IV or V.•A fleet renovation could have disproportionate effects on reducing commuters' exposure.
Abstract
Single-atom catalysts have been widely investigated for several electrocatalytic reactions except electrochemical alcohol oxidation. Herein, we synthesize atomically dispersed platinum on ...ruthenium oxide (Pt
1
/RuO
2
) using a simple impregnation-adsorption method. We find that Pt
1
/RuO
2
has good electrocatalytic activity towards methanol oxidation in an alkaline media with a mass activity that is 15.3-times higher than that of commercial Pt/C (6766 vs. 441 mA mg
‒1
Pt
). In contrast, single atom Pt on carbon black is inert. Further, the mass activity of Pt
1
/RuO
2
is superior to that of most Pt-based catalysts previously developed. Moreover, Pt
1
/RuO
2
has a high tolerance towards CO poisoning, resulting in excellent catalytic stability. Ab initio simulations and experiments reveal that the presence of Pt‒O
3f
(3-fold coordinatively bonded O)‒Ru
cus
(coordinatively unsaturated Ru) bonds with the undercoordinated bridging O in Pt
1
/RuO
2
favors the electrochemical dehydrogenation of methanol with lower energy barriers and onset potential than those encountered for Pt‒C and Pt‒Ru.
Cycling of black carbon in the ocean Coppola, Alysha I.; Druffel, Ellen R. M.
Geophysical research letters,
16 May 2016, Letnik:
43, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Black carbon (BC) is a by‐product of combustion from wildfires and fossil fuels and is a slow‐cycling component of the carbon cycle. Whether BC accumulates and ages on millennial time scales in the ...world oceans has remained unknown. Here we quantified dissolved BC (DBC) in marine dissolved organic carbon isolated by solid phase extraction at several sites in the world ocean. We find that DBC in the Atlantic, Pacific, and Arctic oceans ranges from 1.4 to 2.6 μM in the surface and is 1.2 ± 0.1 μM in the deep Atlantic. The average 14C age of surface DBC is 4800 ± 620 14C years and much older in a deep water sample (23,000 ± 3000 14C years). The range of DBC structures and 14C ages indicates that DBC is not homogeneous in the ocean. We show that there are at least two distinct pools of marine DBC, a younger pool that cycles on centennial time scales and an ancient pool that cycles on >105 year time scales.
Key Points
DBC in the Atlantic, Pacific, and Arctic oceans ranges from 1.4 to 2.6 μM in DOC isolated by SPE
The average surface DBC is 4800 ±− 620 14C years and is 23,000 ±− 3000 14C years in the deep
DBC is not homogeneous indicating that there are at least two distinct pools of marine DBC
With the increased concentrations and kinds of refractory organic contaminants (ROCs) in aquatic environments, many previous reviews systematically summarized the applications of carbon-based ...materials in the adsorption and catalytic degradation of ROCs for their economically viable and environmentally friendly behavior. Interestingly, recent studies indicated that carbon-based materials in natural environment can also mediate the transformation of ROCs directly or indirectly due to their abundant persistent free radicals (PFRs). Understanding the formation mechanisms of PFRs in carbo-based materials and their interactions with ROCs is essential to develop their further applications in environment remediation. However, there is no comprehensive review so far about the direct and indirect removal of ROCs mediated by PFRs in amorphous, porous and crystalline carbon-based materials. The review aims to evaluate the formation mechanisms of PFRs in carbon-based materials synthesized through pyrolysis and hydrothermal carbonization processes. The influence of synthesis conditions (temperature and time) and carbon sources on the types as well as the concentrations of PFRs in carbon-based materials are also discussed. In particular, the effects of metals on the concentrations and types of PFRs in carbon-based materials are highlighted because they are considered as the catalysts for the formation of PFRs. The formation mechanisms of reactive species and the further transformation mechanisms of ROCs are briefly summarized, and the surface properties of carbon-based materials including surface area, types and number of functional groups, etc. are found to be the key parameters controlling their activities. However, due to diversity and complexity of carbon-based materials, the exact relationships between the activities of carbon-based materials and PFRs are still uncertain. Finally, the existing problems and current challenges for the ROCs transformation with carbon-based materials are also pointed out.
Display omitted
•Abundant of PFRs formed in carbon-based materials during the synthesis process.•The PFRs types and concentrations affected by synthesis conditions.•The PFRs can activate oxidants and reductants to degrade organic contaminants.•The PFRs can directly react with organic contaminants.
•Yields and physicochemical properties of gasification biochar were reviewed.•Various scenarios were presented in terms of biochar applications.•Gasification systems were evaluated using LCA.•A ...concept of balancing syngas and biochar production was proposed.•Challenges and solutions related to gasification biochar were discussed.
This review lays great emphasis on production and characteristics of biochar through gasification. Specifically, the physicochemical properties and yield of biochar through the diverse gasification conditions associated with various types of biomass were extensively evaluated. In addition, potential application scenarios of biochar through gasification were explored and their environmental implications were discussed. To qualitatively evaluate biochar sustainability through the gasification process, all gasification products (i.e., syngas and biochar) were evaluated via life cycle assessment (LCA). A concept of balancing syngas and biochar production for an economically and environmentally feasible gasification system was proposed and relevant challenges and solutions were suggested in this review.
The role of new energy in carbon neutral ZOU, Caineng; XIONG, Bo; XUE, Huaqing ...
Petroleum exploration and development,
April 2021, 2021-04-00, 2021-04-01, Letnik:
48, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Carbon dioxide is an important medium of the global carbon cycle, and has the dual properties of realizing the conversion of organic matter in the ecosystem and causing the greenhouse effect. The ...fixed or available carbon dioxide in the atmosphere is defined as “gray carbon”, while the carbon dioxide that cannot be fixed or used and remains in the atmosphere is called “black carbon”. Carbon neutral is the consensus of human development, but its implementation still faces many challenges in politics, resources, technology, market, and energy structure, etc. It is proposed that carbon replacement, carbon emission reduction, carbon sequestration, and carbon cycle are the four main approaches to achieve carbon neutral, among which carbon replacement is the backbone. New energy has become the leading role of the third energy conversion and will dominate carbon neutral in the future. Nowadays, solar energy, wind energy, hydropower, nuclear energy and hydrogen energy are the main forces of new energy, helping the power sector to achieve low carbon emissions. “Green hydrogen” is the reserve force of new energy, helping further reduce carbon emissions in industrial and transportation fields. Artificial carbon conversion technology is a bridge connecting new energy and fossil energy, effectively reducing the carbon emissions of fossil energy. It is predicted that the peak value of China's carbon dioxide emissions will reach 110×108 t in 2030. The study predicts that China's carbon emissions will drop to 22×108 t, 33×108 t and 44×108 t, respectively, in 2060 according to three scenarios of high, medium, and low levels. To realize carbon neutral in China, seven implementation suggestions have been put forward to build a new “three small and one large” energy structure in China and promote the realization of China's energy independence strategy.
PDF
