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1.
J Environ Sci (China) ; 99: 281-295, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183708

RESUMO

CO2 capture and utilization (CCU) is an effective strategy to mitigate global warming. Absorption, adsorption and membranes are methods used for CO2 separation and capture, and various catalytic pathways have also been developed for CO2 utilization. Although widely researched and used in industry, these processes are energy-intensive and this challenge needs to be overcome. To realize further optimization, novel materials and processes are continuously being developed. New generation materials such as ionic liquids (ILs) have shown promising potential for cost-effective CO2 capture and utilization. This study reviews the current status of ILs-based solvents, adsorbents, membranes, catalysts and their hybrid processes for CO2 capture and utilization. The special properties of ILs are integrated into new materials through hybridization, which significantly improves the performance in the process of CCU.


Assuntos
Líquidos Iônicos , Adsorção , Dióxido de Carbono , Catálise , Solventes
2.
J Environ Sci (China) ; 99: 336-345, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183712

RESUMO

This study experimentally studied the dispersion of exhaled pollutant in the breathing microenvironment (BM) in a room equipped with a displacement ventilation (DV) system and indoor air stability conditions (i.e., stable and unstable conditions). The vertical temperature differences and the carbon dioxide (CO2) concentration in the BM were measured. Results show that when DV is combined with the stable condition (DS), pollutant tends to accumulate in the BM, leading to a high pollutant concentration in this region. Whereas, when DV is combined with the unstable condition (DU), pollutant diffuses to a relatively wider area beyond the BM, thus the pollutant concentration in the BM is substantially reduced. Moreover, increasing the flow rate can reduce the pollutant concentration in the BM of the DS but yields little difference of the DU. In addition, personal exposure intensity increases with time, and the DS has a relatively higher increase rate than DU. The results suggest that indoor air stability will affect the performance of DV systems. DS will lead to a higher health risk for people when they stay in the indoor environment with pollutant sources, and DU is recommended for minimizing pollutant level in the BM in order to reduce the pollutant concentration and providing better air environments for the occupants.


Assuntos
Poluição do Ar em Ambientes Fechados , Poluentes Ambientais , Poluição do Ar em Ambientes Fechados/análise , Dióxido de Carbono , Humanos , Ventilação
3.
Sci Total Environ ; 750: 141688, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32835964

RESUMO

The outbreak of coronavirus disease 2019 (COVID-19) has caused tremendous loss to human life and economic decline in China and worldwide. It has significantly reduced gross domestic product (GDP), power generation, industrial activity and transport volume; thus, it has reduced fossil-related and cement-induced carbon dioxide (CO2) emissions in China. Due to time delays in obtaining activity data, traditional emissions inventories generally involve a 2-3-year lag. However, a timely assessment of COVID-19's impact on provincial CO2 emission reductions is crucial for accurately understanding the reduction and its implications for mitigation measures; furthermore, this information can provide constraints for modeling studies. Here, we used national and provincial GDP data and the China Emission Accounts and Datasets (CEADs) inventory to estimate the emission reductions in the first quarter (Q1) of 2020. We find a reduction of 257.7 Mt. CO2 (11.0%) over Q1 2019. The secondary industry contributed 186.8 Mt. CO2 (72.5%) to the total reduction, largely due to lower coal consumption and cement production. At the provincial level, Hubei contributed the most to the reductions (40.6 Mt) due to a notable decrease of 48.2% in the secondary industry. Moreover, transportation significantly contributed (65.1 Mt), with a change of -22.3% in freight transport and -59.1% in passenger transport compared with Q1 2019. We used a point, line and area sources (PLAS) method to test the GDP method, producing a close estimate (reduction of 10.6%). One policy implication is a change in people's working style and communication methods, realized by working from home and holding teleconferences, to reduce traffic emissions. Moreover, GDP is found to have potential merit in estimating emission changes when detailed energy activity data are unavailable. We provide provincial data that can serve as spatial disaggregation constraints for modeling studies and further support for both the carbon cycle community and policy makers.


Assuntos
Infecções por Coronavirus , Coronavirus , Pandemias , Pneumonia Viral , Betacoronavirus , Dióxido de Carbono/análise , China , Humanos
4.
Sci Total Environ ; 753: 142228, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33207473

RESUMO

This research examines the heterogeneous dynamic links among healthcare expenditures, land urbanization, and CO2 emissions across the development levels of China. To this end, data of 27 Chinese provinces are considered from 1999 to 2018. Theoretically, this research developed a healthcare expenditures-augmented Stochastic Impacts of Regression by Population, Affluence, and Technology (STIRPAT) model to incorporate healthcare expenditures as a determinant of affluence. Empirically, this research established a system of simultaneous equations based on the healthcare expenditures-augmented STIRPAT model to estimate the links among the variables. As a pre-analysis, second-generation Westerlund cointegration is applied and found the long-term equilibrium association among the variables. The long-run estimations and short-run causality are done by employing dynamic common correlated effects mean group method (DCCEMGM) and Dumitrescu-Hurlin causality. A heterogeneous long-run equilibrium linkage is confirmed to exist among the variables of interest. Concerning the long-run estimates, firstly, the healthcare expenditures growth and land urbanization exhibited a bilateral positive link. Secondly, CO2 emissions and healthcare expenditures growth manifested the existence of a bilateral positive link. And thirdly, a unilateral positive (negative) link is revealed to exist from a linear term (squared term) of land urbanization to CO2 emissions. Concerning the short-run results, firstly, a bilateral causal bond exists between the land urbanization and healthcare expenditures growth. Secondly, a bilateral causal bond prevails between CO2 emissions growth and healthcare expenditures growth. Finally, a unilateral causal bond is operational from land urbanization to CO2 emissions growth. In terms of the nature of the link, the long-run findings are consistent across the data samples. However, considering the degree of influence, heterogeneity is confirmed across the development levels for both long- and short-run. It infers that relatively more (less) developed regions showed relatively strong (weak) influence. Based on empirical findings, relevant policies are recommended.


Assuntos
Desenvolvimento Econômico , Urbanização , Dióxido de Carbono/análise , China , Gastos em Saúde
5.
Sci Total Environ ; 752: 142190, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33207513

RESUMO

Mangrove, seagrass, and coral habitats often lie adjacent to each other in the tropics and subtropics. Lateral carbon fluxes and their consecutive effects on CO2 dynamics and air-water fluxes along the ecosystem continuum are often overlooked. We measured the partial pressure of CO2 in water and associated biogeochemical parameters with a high temporal resolution and estimated air-water CO2 fluxes along the ecosystem continuum. Their lateral fluxes were estimated by using a biogeochemical mass-balance model. The results showed that the waters surrounding mangrove, seagrass, and coral habitats acted as a strong, moderate, and weak source of atmospheric CO2, respectively. The mangrove zone acted as a net source for TAlk, DIC, and DOC, but as a net sink for POC. The contribution of riverine and mangrove-derived OM was substantially high in mangrove sediment, indicating that net transport of POC towards the coastal sea was suppressed by the sediment trapping function of mangroves. The seagrass zone acted as a net source of all carbon forms and TAlk, whereas the coral zone acted as a net sink of TAlk, DIC, and DOC. The lateral transport of carbon from mangroves and rivers offset atmospheric CO2 uptake in the seagrass zone. DOC degradation might increase DIC, and other biogeochemical processes facilitate the functioning of the coral zone as a DOC sink. However, as a result of DIC uptake by autotrophs, mainly in the coral zone, the whole ecosystem continuum was a net sink of DIC and atmospheric CO2 evasion was lowered. We conclude that lateral transport of riverine and mangrove-derived DIC, TAlk, and DOC affect CO2 dynamics and air-water fluxes in seagrass and coral ecosystems. Thus, studies of lateral carbon fluxes at local and regional scales can improve global carbon budget estimates.


Assuntos
Antozoários , Ecossistema , Animais , Carbono , Dióxido de Carbono , Áreas Alagadas
6.
Sci Total Environ ; 750: 141566, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32882493

RESUMO

Salt marshes, due to their capability to bury soil carbon (C), are potentially important regional C sinks. Efforts to restore tidal flow to former salt marshes have increased in recent decades in New England (USA), as well as in some other parts of the world. In this study, we investigated plant biomass and carbon dioxide (CO2) fluxes at four sites where restoration of tidal flow occurred five to ten years prior to the study. Site elevation, aboveground biomass, CO2 flux, and porewater chemistry were measured in 2015 and 2016 in both restored marshes and adjacent marshes where tidal flow had never been restricted. We found that the elevation in restored marsh sites was 2-16 cm lower than their natural references. Restored marshes where porewater chemistry was similar to the natural reference had greater plant aboveground biomass, gross ecosystem production, ecosystem respiration, as well as net ecosystem CO2 exchange (NEE) than the natural reference, even though they had the same plant species. We also compared respiration rates in aboveground biomass (AR) and soil (BR) during July 2016, and found that restored marshes had higher AR and BR fluxes than natural references. Our findings indicated that well-restored salt marshes can result in greater plant biomass and NEP, which has the potential to enhance rates of C sequestration at 10-yrs post restoration. Those differences were likely due to lower elevation and greater flooding frequency in the recently restored marshes than the natural marsh. The inverse relationship between elevation and productivity further suggests that, where sea-level rise rate does not surpass the threshold of plant survival, the restoration of these salt marshes may lead to enhanced organic and mineral sedimentation, extending marsh survival under increased sea level, and recouping carbon stocks that were lost during decades of tidal restriction.


Assuntos
Dióxido de Carbono , Áreas Alagadas , Biomassa , Dióxido de Carbono/análise , Ecossistema , New England
7.
Sci Total Environ ; 750: 141732, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32882500

RESUMO

A novel electrochemical oxidation-methanogenesis (EO-M) system was proposed for the first time to simultaneously achieve antibiotic degradation and a bioelectrochemical conversion of CO2 to CH4 with low energy costs. A dual-chamber system was installed with an antimony-doped tin oxide anode (Ti/SnO2-Sb) for the electrocatalytic generation of hydroxyl radicals to degrade ciprofloxacin (CIP), and a CO2-reducing methanogenic biocathode was enriched based on a three-dimensional (3D) graphitized granular activated carbon (GGAC) for microbial electromethanogenesis. The anode achieved removal efficiencies as high as 99.99% and 90.53% for CIP (14 mL, 50 mg L-1) and the chemical oxygen demand (COD, 89 mg L-1), respectively. The biocathode was rapidly enriched within 15 days and exhibited a methane production rate that stabilized at 15.12 ± 1.82 m3 m-3 d-1; additionally, the cathodic coulombic efficiency reached 71.76 ± 17.24%. The energy consumption of CIP degradation was reduced by 3.03 Wh L-1 compared to that of a single electrochemical oxidation system due to the lower cathodic overpotential of CO2 bioelectrochemical reduction in the EO-M system. A detailed analysis of the biofilm evolution in the 3D biocathode during the start-up process demonstrated that the enhanced absorption of extracellular polymeric substances by the GGAC cathode accelerated the enrichment of methanogens and induced the formation of methanogens with a large number of flagella. An analysis of the microbial community showed that a high relative abundance of Methanobacterium movens could promote a flagella-mediated direct electron transfer of the biocathode, eventually reducing the cathodic overpotential and energy costs of the EO-M system.


Assuntos
Antibacterianos , Dióxido de Carbono , Eletrodos , Metano , Methanobacterium
8.
Food Chem ; 334: 127487, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32688178

RESUMO

Biodegradable films poly(butylene adipate-co-butylene terephthalate) (PBAT)/poly(lactic acid) (PLA) incorporated with nano-polyhedral oligomeric silsesquioxane (POSS(epoxy)8) as a reactive compatibilizer were developed by melt processing. Structural, morphological, mechanical, and gas permeability properties of the films were determined. 1H NMR and GPC demonstrated that the POSS(epoxy)8 was chemically bound at the PBAT/PLA boundary phase via an epoxide ring opening reaction. SEM micrographs of impact fracture surfaces demonstrated the POSS(epoxy)8 improved interfacial adhesion between PBAT and PLA matrix. The mechanical properties of the PBAT/PLA films containing POSS(epoxy)8 were enhanced relative to pristine PBAT/PLA films. The water vapor, CO2 and O2 permeability of the PBAT/PLA films were improved by POSS(epoxy)8 addition. PBAT/PLA films containing POSS(epoxy)8 were shown to be superior to pristine PBAT/PLA films and polyethylene films in food storage tests. Results suggest that POSS(epoxy)8 addition during PBAT/PLA film production offers a simple strategy for the production of high performance biodegradable plastic packaging films.


Assuntos
Plásticos Biodegradáveis/química , Embalagem de Alimentos/métodos , Nanocompostos/química , Poliésteres/química , Dióxido de Carbono/química , Armazenamento de Alimentos/métodos , Oxigênio/química , Permeabilidade , Resistência à Tração
9.
Sci Total Environ ; 753: 141922, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32896732

RESUMO

Algal productivity in steady-state cultivation systems depends on important factors such as biomass concentration, solids retention time (SRT), and light intensity. Current modeling of algal growth often ignores light distribution in algal cultivation systems and does not consider all these factors simultaneously. We developed a new algal growth model using a first principles approach to incorporate the effect of light intensity on algal growth while simultaneously considering biomass concentration and SRT. We first measured light attenuation (decay) with depth in an indoor algal membrane bioreactor (A-MBR) cultivating Chlorella sp. We then simulated the light decay using a multi-layer approach and correlated the decay with biomass concentration and SRT in model development. The model was calibrated by delineating specific light absorptivity and half-saturation constant to match the algal biomass concentration in the A-MBR operated at a target SRT. We finally applied the model to predict the maximum algal productivity in both indoor and outdoor A-MBRs. The predicted maximum algal productivities in indoor and outdoor A-MBRs were 6.7 g·m-2·d-1 (incident light intensity 5732 lx, SRT approximately 8 d) and 28 g·m-2·d-1 (sunlight intensity 28,660 lx, SRT approximately 4 d), respectively. The model can be extended to include other factors (e.g., water temperature and carbon dioxide bubbling) and such a modeling framework can be applied to full-scale, continuous flow outdoor systems to improve algal productivity.


Assuntos
Chlorella , Biomassa , Reatores Biológicos , Dióxido de Carbono , Temperatura
10.
Sci Total Environ ; 753: 142050, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32898811

RESUMO

Particulate photocatalysts developed for the solar energy-driven reduction of the greenhouse gas CO2 have a small product range and low specificity. Hybrid photosynthesis expands the number of products with photocatalysts harvesting sunlight and transferring charges to microbes harboring versatile metabolisms for bioproduction. Besides CO2, abiotic photocatalysts have been employed to increase microbial production yields of reduced compounds from organic carbon substrates. Most single-reactor hybrid photosynthesis systems comprise CdS assembled in situ by microbial activity. This approach limits optimization of the morphology, crystal structure, and crystallinity of CdS for higher performance, which is usually done via synthesis methods incompatible with life. Here, shape and activity optimized CdS nanorods were hydrothermally produced and subsequently applied to Cupriavidus necator for the heterotrophic and autotrophic production of the bioplastic polyhydroxybutyrate (PHB). C. necator with CdS NR under light produced 1.5 times more PHB when compared to the same bacterium with suboptimal commercially-available CdS. Illuminated C. necator with CdS NR synthesized 1.41 g PHB from fructose over 120 h and 28 mg PHB from CO2 over 48 h. Interestingly, the beneficial effect of CdS NR was specific to C. necator as the metabolism of other microbes often employed for bioproduction including yeast and bacteria was negatively impacted. These results demonstrate that hybrid photosynthesis is more productive when the photocatalyst characteristics are optimized via a separated synthesis process prior to being coupled with microbes. Furthermore, bioproduction improvement by CdS-based photocatalyst requires specific microbial species highlighting the importance of screening efforts for the development of performant hybrid photosynthesis.


Assuntos
Cupriavidus necator , Nanotubos , Dióxido de Carbono , Frutose , Hidroxibutiratos
11.
Sci Total Environ ; 753: 142065, 2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-32906051

RESUMO

Although cultured algae and shellfish can be the dominant species in some localized coastal waters, research on the effect of large-scale mariculture on the carbonate system variations in these local waters is still lacking. We conducted five cruises from May to September and studied spatiotemporal variations in the seawater carbonate system in the semi-closed Sanggou Bay, which is famous for its large-scale mariculture. Our results showed that both kelp and bivalve farming induced significant spatiotemporal variations in the carbonate system within the bay. When cultured kelp reached its highest biomass in May, the maximum ΔDIC, ΔpCO2 and ΔpHT between the seawater from the kelp farming area and the non-farming outer bay area was -156 µmol kg-1, -102 µatm and 0.15 pH units, respectively. However, no significant effect of kelp farming on seawater total alkalinity (TA) was observed. Kelp farming also caused the carbonate system variations of seawater from the bivalve farming area. Assuming no kelp was farmed in May, the average pH and pCO2 would reduce by 0.12 pH units and increase by 179 µatm, respectively, in the bivalve farming area. Bivalve farming significantly reduced seawater TA, indicating that fast deposition of calcium carbonate occurred in the bivalve farming area. Although bivalve respiration released CO2 into seawater and elevated seawater pCO2 level and reduced seawater pHT, surprisingly, seawater dissolved inorganic carbon (DIC) reduced significantly in the bivalve farming area. These results indicated that bivalves fixed a larger amount of inorganic carbon by calcification than that released into seawater by respiration. Overall, large-scale kelp and bivalve farming are important biological drivers of variations in the carbonate system within the semi-enclosed Sanggou Bay. Altered carbonate systems by kelp farming may favour calcification of farmed bivalves and provide an essential refuge for these species during the future ocean acidification.


Assuntos
Bivalves , Kelp , Agricultura , Animais , Dióxido de Carbono , Carbonatos , Concentração de Íons de Hidrogênio , Água do Mar
12.
Food Chem ; 336: 127625, 2021 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32771897

RESUMO

The solubility of carbon dioxide (CO2) in the moisture and protein components of cheese matrices and the influence of changing pH, salt and temperature levels remains unclear. In this study, model casein matrices were prepared, by renneting of micellar casein concentrate (MCC), with modulation of salt and pH levels by adding salt and glucono delta-lactone, respectively, to the MCC solutions prior to renneting. Different moisture-to-protein levels were achieved by freeze-drying, incubation of samples at different relative humidities, or by applying varying pressures during gel manufacture. The CO2 solubility of samples decreased linearly with both increasing temperature and salt-in-moisture content, whereas solubility of CO2 increased with increasing pH. A non-linear relationship was observed between CO2 solubility and the moisture-to-protein ratio of experimental samples. Overall, such knowledge may be applied to improve the quality and consistency of eye-type cheese, and in particular to avoid development of undesirable slits and cracks.


Assuntos
Dióxido de Carbono/química , Caseínas/química , Cloreto de Sódio/química , Água/química , Queijo/análise , Concentração de Íons de Hidrogênio , Pressão Parcial , Solubilidade , Temperatura
13.
Food Chem ; 335: 127649, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32738538

RESUMO

Rosa rugosa Thunb. seed oil (RR) extracted by supercritical CO2 was investigated. RR chemical composition, radical scavenging effect and oxidative stability were evaluated. RR aqueous emulsions were examined for cell cytotoxicity, proliferation, redox state and migration using mouse embryonic fibroblast Balb/3T3, human dermal fibroblast NHDF cell lines, and on neoplastic cell lines: acute monocytic leukemia THP-1 and lung adenocarcinoma A549. RR total contents of phytosterols, tocopherols, carotenoids and phenolics were 10115.23, 784.16, 40.32 and 10.30 mg/kg, respectively. Rich antioxidant composition of RR was reflected in its high antioxidant activity (2.1 mM/kg Trolox equivalent) as well as oxidative stability (activation energy 105.6 kJ/mol). The RR emulsions led to marked augmentation of the total cell protein content in BALB/3T3 and NHDF cultures, inhibited cancer cell migration and reduced ROS formation. The studied RR oil proved to have a remarkable combination of bioactive compounds and to exert an antioxidative and chemopreventive effects.


Assuntos
Óleos Vegetais/química , Óleos Vegetais/farmacologia , Rosa/química , Animais , Antioxidantes/química , Antioxidantes/isolamento & purificação , Antioxidantes/farmacologia , Dióxido de Carbono/química , Carotenoides/química , Carotenoides/isolamento & purificação , Carotenoides/farmacologia , Linhagem Celular , Cromatografia com Fluido Supercrítico , Humanos , Camundongos , Oxirredução , Fenóis/química , Fenóis/isolamento & purificação , Fenóis/farmacologia , Fitosteróis/química , Fitosteróis/isolamento & purificação , Fitosteróis/farmacologia , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Óleos Vegetais/isolamento & purificação , Sementes/química , Tocoferóis/química , Tocoferóis/isolamento & purificação , Tocoferóis/farmacologia
14.
Sheng Wu Gong Cheng Xue Bao ; 36(10): 2126-2138, 2020 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-33169577

RESUMO

Development of "liquid sunshine" could be a key technology to deal with the issue of fossil fuel depletion. ß-caryophyllene is a terpene compound with high energy density and has attracted attention for its potential application as a jet fuel. The high temperature and high light-tolerant photosynthetic cyanobacterium Synechococcus elongatus UTEX 2973 (hereafter Synechococcus 2973), whose doubling time is as short as 1.5 h, has great potential for synthesizing ß-caryophyllene using sunlight and CO2. In this study, a production of ~121.22 µg/L ß-caryophyllene was achieved at 96 h via a combined strategy of pathway construction, key enzyme optimization and precursor supply enhancement. In addition, a final production of ~212.37 µg/L at 96 h was realized in a high-density cultivation. To our knowledge, this is the highest production reported for ß-caryophyllene using cyanobacterial chassis and our study provide important basis for high-density fuel synthesis in cyanobacteria.


Assuntos
Biocombustíveis , Dióxido de Carbono , Synechococcus , Biocombustíveis/microbiologia , Dióxido de Carbono/metabolismo , Luz , Fotossíntese , Synechococcus/genética , Synechococcus/metabolismo , Synechococcus/efeitos da radiação
15.
Sci Data ; 7(1): 392, 2020 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-33168822

RESUMO

We constructed a near-real-time daily CO2 emission dataset, the Carbon Monitor, to monitor the variations in CO2 emissions from fossil fuel combustion and cement production since January 1, 2019, at the national level, with near-global coverage on a daily basis and the potential to be frequently updated. Daily CO2 emissions are estimated from a diverse range of activity data, including the hourly to daily electrical power generation data of 31 countries, monthly production data and production indices of industry processes of 62 countries/regions, and daily mobility data and mobility indices for the ground transportation of 416 cities worldwide. Individual flight location data and monthly data were utilized for aviation and maritime transportation sector estimates. In addition, monthly fuel consumption data corrected for the daily air temperature of 206 countries were used to estimate the emissions from commercial and residential buildings. This Carbon Monitor dataset manifests the dynamic nature of CO2 emissions through daily, weekly and seasonal variations as influenced by workdays and holidays, as well as by the unfolding impacts of the COVID-19 pandemic. The Carbon Monitor near-real-time CO2 emission dataset shows a 8.8% decline in CO2 emissions globally from January 1st to June 30th in 2020 when compared with the same period in 2019 and detects a regrowth of CO2 emissions by late April, which is mainly attributed to the recovery of economic activities in China and a partial easing of lockdowns in other countries. This daily updated CO2 emission dataset could offer a range of opportunities for related scientific research and policy making.


Assuntos
Dióxido de Carbono/análise , Materiais de Construção/análise , Monitoramento Ambiental , Emissões de Veículos/análise , Infecções por Coronavirus , Pandemias , Pneumonia Viral
16.
Nat Commun ; 11(1): 5515, 2020 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-33168823

RESUMO

The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing > 3800 species from 189 long-term RAINFOR forest plots. While tree mortality rates vary greatly Amazon-wide, on average trees are as likely to die standing as they are broken or uprooted-modes of death with different ecological consequences. Species-level growth rate is the single most important predictor of tree death in Amazonia, with faster-growing species being at higher risk. Within species, however, the slowest-growing trees are at greatest risk while the effect of tree size varies across the basin. In the driest Amazonian region species-level bioclimatic distributional patterns also predict the risk of death, suggesting that these forests are experiencing climatic conditions beyond their adaptative limits. These results provide not only a holistic pan-Amazonian picture of tree death but large-scale evidence for the overarching importance of the growth-survival trade-off in driving tropical tree mortality.


Assuntos
Ecologia , Florestas , Árvores/crescimento & desenvolvimento , Biomassa , Brasil , Dióxido de Carbono , Sequestro de Carbono , Ecossistema , Monitoramento Ambiental , Modelos Biológicos , Modelos de Riscos Proporcionais , Fatores de Risco , Clima Tropical
17.
Nat Commun ; 11(1): 5172, 2020 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-33057164

RESUMO

The COVID-19 pandemic is impacting human activities, and in turn energy use and carbon dioxide (CO2) emissions. Here we present daily estimates of country-level CO2 emissions for different sectors based on near-real-time activity data. The key result is an abrupt 8.8% decrease in global CO2 emissions (-1551 Mt CO2) in the first half of 2020 compared to the same period in 2019. The magnitude of this decrease is larger than during previous economic downturns or World War II. The timing of emissions decreases corresponds to lockdown measures in each country. By July 1st, the pandemic's effects on global emissions diminished as lockdown restrictions relaxed and some economic activities restarted, especially in China and several European countries, but substantial differences persist between countries, with continuing emission declines in the U.S. where coronavirus cases are still increasing substantially.


Assuntos
Poluentes Atmosféricos/análise , Dióxido de Carbono/análise , Infecções por Coronavirus/epidemiologia , Pneumonia Viral/epidemiologia , Poluentes Atmosféricos/economia , Betacoronavirus , Dióxido de Carbono/economia , Infecções por Coronavirus/economia , Infecções por Coronavirus/prevenção & controle , Monitoramento Ambiental , Combustíveis Fósseis/análise , Combustíveis Fósseis/economia , Humanos , Indústrias/economia , Dióxido de Nitrogênio/análise , Dióxido de Nitrogênio/economia , Pandemias/economia , Pandemias/prevenção & controle , Pneumonia Viral/economia , Pneumonia Viral/prevenção & controle
18.
Sci Total Environ ; 748: 142465, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33113689

RESUMO

Porous structure design is considered to be a promising strategy for the development of effective sorbents for CO2 capture. Herein, a series of carbon nanoflakes with large surface area (up to 2380 m2/g) and high micropore volume (up to 0.896 m3/g) were synthesized from a renewable precursor, cork dust waste, to capture CO2 at atmospheric pressure. The nanoflakes exhibited superior CO2 uptake performance at 1 bar with the maximum capacity of 7.82 and 4.27 mmol/g at 0 and 25 °C, respectively, in sharp contrast to previously reported porous carbon materials. The existence of large numbers of narrow micropores with the pore width less than 0.86 nm and 0.70 nm play a critical role in the CO2 uptake at 0 and 25 °C, respectively. Moreover, the CNFs exhibited good recyclability and high selectivity for CO2 uptake from the mixture of CO2 and N2. By taking advantage of the unique hollow honeycomb cell, the three-layered cell wall structure, as well as the unique chemical composition of a cork precursor, such delicate microporous carbon nanoflakes were able to be achieved by simple thermal pretreatment combined with chemical activation. This bioinspired precursor-synthesis route poses a great potential for the facile production of porous carbons for a variety of diverse applications including CO2 capture.


Assuntos
Dióxido de Carbono , Carbono , Biomassa , Porosidade
19.
Artigo em Inglês | MEDLINE | ID: mdl-33008116

RESUMO

During the first outbreak of the SARS-CoV-2 pandemic the population, focusing primarily on the risk of infection, was generally inattentive to the quality of indoor air. Spain, and the city of Madrid in particular, were among the world's coronavirus hotspots. The country's entire population was subject to a 24/7 lockdown for 45 days. This paper describes a comparative longitudinal survey of air quality in four types of housing in the city of Madrid before and during lockdown. The paper analysed indoor temperatures and variations in CO2, 2.5 µm particulate matter (PM2.5) and total volatile organic compound (TVOC) concentrations before and during lockdown. The mean daily outdoor PM2.5 concentration declined from 11.04 µg/m3 before to 7.10 µg/m3 during lockdown. Before lockdown the NO2 concentration values scored as 'very good' 46% of the time, compared to 90.9% during that period. Although the city's outdoor air quality improved, during lockdown the population's exposure to indoor pollutants was generally more acute and prolonged. Due primarily to concern over domestic energy savings, the lack of suitable ventilation and more intensive use of cleaning products and disinfectants during the covid-19 crisis, indoor pollutant levels were typically higher than compatible with healthy environments. Mean daily PM2.5 concentration rose by approximately 12% and mean TVOC concentration by 37% to 559%. The paper also puts forward a series of recommendations to improve indoor domestic environments in future pandemics and spells out urgent action to be taken around indoor air quality (IAQ) in the event of total or partial quarantining to protect residents from respiratory ailments and concomitantly enhanced susceptibility to SARS-CoV-2, as identified by international medical research.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Infecções por Coronavirus , Pandemias , Pneumonia Viral , Betacoronavirus , Dióxido de Carbono , Cidades , Habitação/classificação , Humanos , Óxido Nítrico , Material Particulado , Espanha , Compostos Orgânicos Voláteis
20.
Environ Sci Process Impacts ; 22(11): 2181-2198, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-33078814

RESUMO

Accelerated warming in the Arctic has led to concern regarding the amount of carbon emission potential from Arctic water bodies. Yet, aquatic carbon dioxide (CO2) and methane (CH4) flux measurements remain scarce, particularly at high resolution and over long periods of time. Effluxes of methane (CH4) and carbon dioxide (CO2) from Toolik Lake, a deep glacial lake in northern Alaska, were measured for the first time with the direct eddy covariance (EC) flux technique during six ice-free lake periods (2010-2015). CO2 flux estimates from the lake (daily average efflux of 16.7 ± 5.3 mmol m-2 d-1) were in good agreement with earlier estimates from 1975-1989 using different methods. CH4 effluxes in 2010-2015 (averaging 0.13 ± 0.06 mmol m-2 d-1) showed an interannual variation that was 4.1 times greater than median diel variations, but mean fluxes were almost one order of magnitude lower than earlier estimates obtained from single water samples in 1990 and 2011-2012. The overall global warming potential (GWP) of Toolik Lake is thus governed mostly by CO2 effluxes, contributing 86-93% of the ice-free period GWP of 26-90 g CO2,eq m-2. Diel variation in fluxes was also important, with up to a 2-fold (CH4) to 4-fold (CO2) difference between the highest nighttime and lowest daytime effluxes. Within the summer ice-free period, on average, CH4 fluxes increased 2-fold during the first half of the summer, then remained almost constant, whereas CO2 effluxes remained almost constant over the entire summer, ending with a linear increase during the last 1-2 weeks of measurements. Due to the cold bottom temperatures of this 26 m deep lake, and the absence of ebullition and episodic flux events, Toolik Lake and other deep glacial lakes are likely not hot spots for greenhouse gas emissions, but they still contribute to the overall GWP of the Arctic.


Assuntos
Dióxido de Carbono , Lagos , Alaska , Regiões Árticas , Dióxido de Carbono/análise , Metano , Estações do Ano
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