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1.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2717-2724, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418197

RESUMO

Rice straw is a potential material for bioenergy production. Elevated atmospheric carbon dioxide (CO2) concentration changed the quantity and quality of rice straw, thus changing its bioenergy production potential. In this experiment, we collected rice straw from China Free Air CO2 Enrichment Platform (FACE). Three rice varieties, Wuyunjing 27, Y Liangyou 900 and Nipponbare N16, were selected from the FACE platform (the CO2 concentration in the experimental group was controlled at 570 µmol ·mol-1, which was 200 µmol ·mol-1 higher than the control group), the chemical composition of which was analyzed. The results showed that elevated CO2 concentration significantly increased C content, C/N, and the content of non-structural carbohydrates in straw. Elevated CO2 concentration significantly increased total sugar release by 8.8%, 6.7% and 9.9% in Wuyunjing 27, Y liangyou 900 and N16, respectively. Elevated CO2 concentration significantly enhanced the biomass of N16 straw, but had no effect on the straw biomass of the other two rice varieties. The total sugar yield of N16 increased most significantly with elevated CO2 concentration, reaching 19.2%. Our results indicated that elevated CO2 concentration could improve the quality and quantity of rice straw, thereby increasing the utilization potential of biofuel.


Assuntos
Dióxido de Carbono/análise , Oryza/química , Atmosfera/química , Biomassa , China
2.
Sci Total Environ ; 691: 1144-1154, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466196

RESUMO

Rising atmospheric carbon dioxide (CO2) may stimulate the proliferation of cyanobacteria. To investigate the possible physiological responses of cyanobacteria to elevated CO2 at different nutrient levels, Microcystis aeruginosa were exposed to different concentrations of CO2 (400, 1100, and 2200 ppm) under two nutrient regimes (i.e., in nutrient-rich and nutrient-poor media). The results indicated that M. aeruginosa differed in its responses to elevated atmospheric CO2 at different nutrient levels. The light utilization efficiency and photoprotection of photosystem II were improved by elevated CO2, particularly when cells were supplied with abundant nutrients. In nutrient-poor media, both total organic carbon and the polysaccharide/protein ratio of the extracellular polymeric substance increased with elevated CO2, accompanied by high cellular carbon/nitrogen ratios. Besides, cells growing with fewer nutrients were more prone to suffer intracellular acidification with elevated CO2 than those growing with abundant nutrients. Nonetheless, alkaline phosphate activity of cyanobacteria was improved by high CO2, provided that reduced pH was in the optimum range for alkaline phosphate activity. Nitrate reductase activity was inhibited by elevated CO2 regardless of nutrient levels, leading to a reduced nitrate uptake. These changes indicate that the biogeochemical cycling of nutrients would be affected by higher atmospheric CO2 conditions. Overall, cyanobacteria in eutrophic waters may benefit more than in oligotrophic waters from rising atmospheric CO2 concentrations, and evaluations of the influence of rising atmospheric CO2 on algae should account for the nutrient level of the ecosystem.


Assuntos
Atmosfera/química , Dióxido de Carbono/análise , Cianobactérias/fisiologia , Eutrofização
3.
Environ Monit Assess ; 191(9): 563, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31410642

RESUMO

This study aims to determine a baseline for natural soil carbon dioxide (CO2) flux at the surface based on long-term field measurements, with the ultimate purpose to detect the gas leakage at CO2 geological storage sites. CO2 surface monitoring is a tool that measures the safety and effectiveness of CO2 capture and storage (CCS), a technology which is believed to be a reliable approach to mitigate the CO2 emission. However, the fluctuations of naturally occurring CO2 in soil layers complicate the leakage detection as the soil connects both the underground layers and the atmosphere. In this regard, this study not only investigates the natural surface CO2 flux behavior but also develops an equation to estimate the surface CO2 flux with respect to the soil moisture content and temperature. To meet this end, two values within the CO2 flux equation were defined and calculated based on the field measurements; a, representing a water saturation-dependent value, and b, representing the temperature sensitivity (independent of the water saturation). The results show a good agreement between estimated and measured data. Upon which, the maximum baseline for surface CO2 flux was derived and used as a threshold to detect the potential CO2 leakage in the candidate field (INAS, Japan).


Assuntos
Dióxido de Carbono/análise , Monitoramento Ambiental/métodos , Solo/química , Atmosfera/química , Geologia , Japão , Temperatura Ambiente , Água/química
4.
Nature ; 571(7763): 99-102, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31270485

RESUMO

The long-term cooling, decline in the partial pressure of carbon dioxide, and the establishment of permanent polar ice sheets during the Neogene period1,2 have frequently been attributed to increased uplift and erosion of mountains and consequent increases in silicate weathering, which removes atmospheric carbon dioxide3,4. However, geological records of erosion rates are potentially subject to averaging biases5,6, and the magnitude of the increase in weathering fluxes-and even its existence-remain debated7-9. Moreover, an increase in weathering scaled to the proposed erosional increase would have removed nearly all carbon from the atmosphere10, which has led to suggestions of compensatory carbon fluxes11-13 in order to preserve mass balance in the carbon cycle. Alternatively, an increase in land surface reactivity-resulting from greater fresh-mineral surface area or an increase in the supply of reactive minerals-rather than an increase in the weathering flux, has been proposed to reconcile these disparate views8,9. Here we use a parsimonious carbon cycle model that tracks two weathering-sensitive isotopic tracers (stable 7Li/6Li and cosmogenic 10Be/9Be) to show that an increase in land surface reactivity is necessary to simultaneously decrease atmospheric carbon dioxide, increase seawater 7Li/6Li and retain constant seawater 10Be/9Be over the past 16 million years. We find that the global silicate weathering flux remained constant, even as the global silicate weathering intensity-the fraction of the total denudation flux that is derived from silicate weathering-decreased, sustained by an increase in erosion. Long-term cooling during the Neogene thus reflects a change in the partitioning of denudation into weathering and erosion. Variable partitioning of denudation and consequent changes in silicate weathering intensity reconcile marine isotope and erosion records with the need to maintain mass balance in the carbon cycle and without requiring increases in the silicate weathering flux.


Assuntos
Atmosfera/química , Ciclo do Carbono , Dióxido de Carbono/análise , Dióxido de Carbono/história , Temperatura Baixa , Sedimentos Geológicos/química , Geologia/história , Retroalimentação , Sedimentos Geológicos/análise , História Antiga , Camada de Gelo/química , Modelos Teóricos , Rios/química , Água do Mar/química , Silicatos/análise
5.
J Environ Radioact ; 208-209: 106006, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31284164

RESUMO

Original data on radionuclide activities in air emissions of Russian NPPs are presented based on direct on-site measurements in vent stacks of NPPs during an extensive survey in 2017-2018. For the first time, the detailed inventories of radionuclides in the air releases were directly measured for all types of nuclear reactors, employed in the Russian NPPs. Based on the results of measurements, annual doses for local populations around the Russian NPPs were estimated. The technogenic radionuclides, detected in the air emissions, were ranked according to their contribution in the annual dose. 14C is the major contributor for the annual dose from the atmospheric releases of LWGR reactors - almost 98% for Bilibino NPP's EGP-6 reactor, and up to 86% for RBMK-1000 reactors (Smolensk NPP). For PWR reactors (VVER) contribution to the annual dose from atmospheric releases is formed mostly by tritium, 14C and noble gases. Estimated annual doses for local populations in the vicinity of the Russian NPPs do not exceed 10-5 Sv/year. Atmospheric releases of 60Co, 134Cs, 137Cs and other aerosols, involved in the routine monitoring programs of Russian NPPs, do not contribute significantly to the annual dose. Based on these results, 14C and tritium will be included in the monitoring programs of atmospheric release control at all Russian NPPs; maximal permissible levels of annual releases for 14C and tritium will be established since 2019.


Assuntos
Poluentes Radioativos do Ar/análise , Monitoramento de Radiação , Poluentes Radioativos da Água/análise , Atmosfera/química , Radioisótopos de Césio/análise , Doses de Radiação , Federação Russa
6.
J Environ Radioact ; 208-209: 106014, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31323601

RESUMO

This work focuses on the usability of event zero time determination using xenon isotopic activity ratios. Two data sets from Nevada underground nuclear test and Fukushima accident debris were used to calculate the age of radioxenon release by considering three kinds of radioactivity release radionuclide sources: nuclear explosion scenarios, nuclear power reactor release and medical isotopes production facilities release. Typical nuclear power reactor releases were characterized and reference values are proposed for six isotopic activity ratios, which data can be considered as reference point of nuclear reactor effluents at the time of their release obtained from real observations. The same reference values of isotopic activity ratio are given for medical isotopes production facilities releases. The purpose of this study is to evaluate the use of zero-time calculation for source characterization under the assumption that a hypothesis about the event time is made. The event time information may come from a seismo-acoustic event of interest or an inverse atmospheric transport simulation or other context information. For both data sets used in this study, the age precisions are calculated and the time precision difference is evaluated and used as a parameter for the characterization of each radionuclide event. Almost all radioxenon isotopic activity ratios are found to correctly identifying the source type of the radionuclide events studied in this work. The results from this radionuclide events characterization study may be helpful for event screening activities of the Comprehensive Nuclear Test Ban Treaty Organization (CTBTO).


Assuntos
Poluentes Radioativos do Ar/análise , Monitoramento de Radiação , Radioisótopos de Xenônio/análise , Atmosfera/química , Nevada , Armas Nucleares , Valores de Referência
7.
Environ Pollut ; 253: 49-60, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31302402

RESUMO

Carbonaceous aerosols (CAs) scatter and absorb incident solar radiation in the atmosphere, thereby influencing the regional climate and hydrological cycle, particularly in the Third Pole (TP). Here, we present the characteristics of CAs at 19 observation stations from the Atmospheric Pollution and Cryospheric Change network to obtain a deep understanding of pollutant status in the TP. The organic carbon (OC) and elemental carbon (EC) concentrations decreased noticeably inwards from outside to inland of the TP, consistent with their emission load and also affected by transport process and meteorological condition. Urban areas, such as Kathmandu, Karachi, and Mardan, exhibited extremely high OC and EC concentrations, with low and high values occurring in the monsoon and non-monsoon seasons, respectively. However, remote regions inland the TP (e.g., Nam Co and Ngari) demonstrated much lower OC and EC concentrations. Different seasonal variations were observed between the southern and northern parts of the TP, suggesting differences in the patterns of pollutant sources and in distance from the sources between the two regions. In addition to the influence of long-range transported pollutants from the Indo-Gangetic Plain (IGP), the TP was affected by local emissions (e.g., biomass burning). The OC/EC ratio also suggested that biomass burning was prevalent in the center TP, whereas the marginal sites (e.g., Jomsom, Dhunche, and Laohugou) were affected by fossil fuel combustion from the up-wind regions. The mass absorption cross-section of EC (MACEC) at 632 nm ranged from 6.56 to 14.7 m2 g-1, with an increasing trend from outside to inland of the TP. Urban areas had low MACEC values because such regions were mainly affected by local fresh emissions. In addition, large amount of brown carbon can decrease the MACEC values in cities of South Asia. Remote sites had high MACEC values because of the coating enhancement of aerosols. Influenced by emission, transport process, and weather condition, the CA concentrations and MACEC presented decreasing and increasing trends, respectively, from outside to inland of the TP.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Material Particulado/análise , Aerossóis/análise , Ásia , Atmosfera/química , Biomassa , Carbono/análise , Cidades , Clima , Poluição Ambiental , Combustíveis Fósseis , Estações do Ano , Tempo (Meteorologia) , Vento
8.
Nature ; 571(7765): 335-342, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31316194

RESUMO

Research reported during the past decade has shown that global warming is roughly proportional to the total amount of carbon dioxide released into the atmosphere. This makes it possible to estimate the remaining carbon budget: the total amount of anthropogenic carbon dioxide that can still be emitted into the atmosphere while holding the global average temperature increase to the limit set by the Paris Agreement. However, a wide range of estimates for the remaining carbon budget has been reported, reducing the effectiveness of the remaining carbon budget as a means of setting emission reduction targets that are consistent with the Paris Agreement. Here we present a framework that enables us to track estimates of the remaining carbon budget and to understand how these estimates can improve over time as scientific knowledge advances. We propose that application of this framework may help to reconcile differences between estimates of the remaining carbon budget and may provide a basis for reducing uncertainty in the range of future estimates.


Assuntos
Atmosfera/química , Dióxido de Carbono/análise , Aquecimento Global/prevenção & controle , Aquecimento Global/estatística & dados numéricos , Metas , Modelos Teóricos , Temperatura Ambiente , Terra (Planeta) , Política Ambiental/legislação & jurisprudência , Retroalimentação , Aquecimento Global/legislação & jurisprudência , Atividades Humanas/legislação & jurisprudência , Cooperação Internacional/legislação & jurisprudência , Paris , Reprodutibilidade dos Testes , Fatores de Tempo , Incerteza
9.
Chemosphere ; 233: 966-974, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340424

RESUMO

The lower stretch of the perennial transboundary river Ganga is known as the Hooghly River (HR) in India. Despite the strict ban, HR has been evidenced with residues of pesticidal persistent organic pollutants (POPs) from primary and secondary sources. Hence surface water sampling and passive air sampling (PAS) were conducted along the urban and suburban transects and discharge points to study the fate of pesticidal (POPs along the HR. Excluding the discharge points, the mean concentration of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and endosulfan (ENDO) were 6 ng/L, 4 ng/L and 36 ng/L in surface water and 888 pg/m3, 1689 pg/m3 and 429 pg/m3 in atmosphere respectively. Percentage composition and diagnostic ratios strongly suggest ongoing use of technical HCH, DDT and endosulfan. Elevated endosulfan in surface water has been related to its usage during fishing. Except for p,p'-DDE, α-Endo and ß-Endo, fluxes at the air-water interface showed net deposition from air to water for all the OCPs in urban and suburban transects. The estimated eco-toxicological risk assessment showed risk on lower trophic organisms due to DDT and lindane mostly at the discharge points. Endosulfan can pose potential risk to the edible fishe species in the HR.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Praguicidas/análise , Rios/química , Poluentes Químicos da Água/análise , Atmosfera/química , DDT/análise , Diclorodifenil Dicloroetileno/análise , Endossulfano/análise , Hexaclorocicloexano/análise , Índia , Água/química
11.
Environ Pollut ; 253: 207-220, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31310871

RESUMO

Characterizing the vertical distribution of aerosol optical properties is crucial to reduce the uncertainty in quantifying the radiative forcing and climate effects of aerosols. The analysis of four-year (2007-2010) Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) lidar measurements revealed the existence of tropospheric aerosol layers associated with the Asian summer monsoon. The measurements of five typical aerosol optical and microphysical parameters were used to explore the properties, spatial/vertical distributions, annual evolution of tropopause aerosols over the South Asia region. Results extracted from various latitude-height and longitude-height cross sections of aerosol extinction coefficient at 532 and 1064 nm, backscatter coefficient at 532 nm, and depolarization ratio at 532 nm demonstrated that a large amount of aerosols vertically extended up to the tropopause (12 km) during the monsoon season over the north Arabian Sea, India, north Bay of Bengal, and equatorial Indian Ocean, finally reaching the southeast of the Tibetan Plateau. Convective transport associated with Asian summer monsoon is an important factor controlling the vertical distribution of tropopause aerosols. The evolution of aerosol scattering ratio at 532 nm indicated that from equatorial Indian Ocean to South Asia, there exists an upward tilting and ascending structure of the aerosols layer during the monsoon season, which typically indicates enhanced aerosols over the Asian monsoon region. Information on aerosol size distribution and detailed composition are needed for better understanding the nature and origin of this aerosol layer. Enhancement of the tropopause aerosols should be considered in the future studies in evaluating the regional or global climate systems. Further satellite observations of aerosols and in-situ observations are also urgently needed to diagnose this aerosol layer, which likely originate from anthropogenic emissions.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Ásia , Atmosfera/química , Clima , Índia , Oceano Índico , Estações do Ano
12.
Environ Pollut ; 253: 259-267, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31319242

RESUMO

Seasonal and diurnal variations of carbonyl compounds were investigated in the ambient air of a mountainous city in China, from September 2014 to July 2015. The most abundant carbonyl compounds are formaldehyde, acetaldehyde and acetone, propionaldehyde and methacryladehyde (MACR), which were all measured in most samples. The average concentrations of formaldehyde, acetaldehyde, acetone, propionaldehyde and MACR in the atmosphere in Changsha were broken down into each season: 6.57, 3.29, 3.66, 0.67 and 0.54 µg/m3 respectively during Spring, 14.09, 8.28, 9.02, 1.28 and 0.6 µg/m3, respectively during Summer, 9.24, 5.48, 8.62, 0.73 and 0.62 µg/m3, respectively during Autumn, and 5.88, 4.84, 7.84, 0.87 and 0.26 µg/m3 respectively during Winter. And majority of the species had higher concentration during noon, showing photochemical oxidation and human activities played an important role in diurnal variation. The highest average C1/C2 (formaldehyde/acetaldehyde) ratio was observed in summer (2.10) compared to those (1.33-2.03) in other seasons, implying the photochemical activities had a positive effect on increasing the ratio of C1/C2. In this study, the monthly concentration of formaldehyde produced from isoprene accounts for 4.8%-39.1% of formaldehyde in ambient air. Strong correlation among some carbonyl compounds means that they came from the same sources. Photochemical reaction was the main source of carbonyl compounds in summer and vehicular exhaust (gasoline and diesel engines) in winter. Changsha is not a completely urbanized city and it is rich in vegetation of broadleaf evergreen shrubs. Both atmospheric photochemical reactions and anthropogenic sources, including vehicular exhaust and industrial processes, dominate the levels of carbonyls. The ILTCR and HQ values of formaldehyde and acetaldehyde are 1.23E-04 and 1.34E-05, 2.80E-01 and 1.86E-01, respectively.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Acetaldeído/análise , Acetona , Aldeídos , Atmosfera/química , China , Cidades , Formaldeído/análise , Humanos , Estações do Ano , Emissões de Veículos/análise
13.
Environ Monit Assess ; 191(7): 418, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31175476

RESUMO

Millions of people have an allergic reaction to pollen. The impact of pollen allergies is on the rise due to increased pollen levels caused by global warming and the spread of highly invasive weeds. The production, release, and dispersal of pollen depend on the ambient weather conditions. The temperature, rainfall, humidity, cloud cover, and wind are known to affect the amount of pollen in the atmosphere. In the past, various regression techniques have been applied to estimate and forecast the daily pollen concentration in the atmosphere based on the weather conditions. In this research, machine learning methods were applied to the Next Generation Weather Radar (NEXRAD) data to estimate the daily Ambrosia pollen over a 300 km × 300 km region centered on a NEXRAD weather radar. The Neural Network and Random Forest machine learning methods have been employed to develop separate models to estimate Ambrosia pollen over the region. A feasible way of estimating the daily pollen concentration using only the NEXRAD radar data and machine learning methods would lay the foundation to forecast daily pollen at a fine spatial resolution nationally.


Assuntos
Alérgenos/análise , Antígenos de Plantas/análise , Atmosfera/química , Monitoramento Ambiental/métodos , Aprendizado de Máquina , Extratos Vegetais/análise , Pólen , Radar , Previsões , Oklahoma , Tempo (Meteorologia)
14.
Environ Sci Pollut Res Int ; 26(22): 22846-22855, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31175574

RESUMO

The aim of this work was to evaluate simultaneously the effect of produced ethanolic biodiesel from several feedstocks (soybean, crambe, macaw, sunflower, and waste cooking oil) and engine operational conditions (low and high engine speed) during combustion of biodiesel/diesel blends on the N2O, NOx, NO, CO2, and CO emission levels in the atmosphere. The biodiesel samples were prepared in one and/or two reaction steps, according to the acid index of each raw material, by esterification using H2SO4 and/or chemical transesterification using sodium ethoxide, both, through ethanolic route. The quality of the produced biodiesels was confirmed by ASTM/EN specifications. Then, biodiesel/diesel blends were prepared according to the following proportions: 10% (B10), 15% (B15), 25% (B25), and 50% (B50). In general way, all raw materials under combustion at low and high engine speed contributed to the formation of NOx and this effect was more drastically increased as the biodiesel concentration in the blends increases. N2O presented a similar behavior except for blends containing crambe and macaw biodiesel whose emissions were slightly reduced as a function of biodiesel content in these blends. Then, Principal component analysis (PCA) was applied to discriminate the effect of engine operating conditions, biodiesel kind, and biodiesel content in the blends during their combustion on the exhaust emissions. The attained results point to crambe and macaw as more environmentally sustainable feedstocks for biodiesel production because they generate less greenhouse gas emissions. These results are particularly attractive considering that, both, crambe and macaw are non-edible feedstocks with great potential for biodiesel production.


Assuntos
Poluentes Atmosféricos/análise , Atmosfera/química , Biocombustíveis/análise , Monitoramento Ambiental , Emissões de Veículos/análise , Esterificação , Etanol/análogos & derivados , Gases de Efeito Estufa
15.
Chemosphere ; 232: 453-461, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31158640

RESUMO

In this work, we develop a model able to predict the equilibrium separation of gases due to differences in their molecular weights and the action of gravity. The separation of H, He, O, and N2 with altitude is a characteristic phenomenon of the heterosphere. The model is able to qualitatively recreate the compositional profile of the whole heterosphere from a single composition measurement. The model is applied to the separation of air components and pollutants by empty wells drilled on the planet surface. It predicts that the separation of gases would be possible in wells deep enough under equilibrium. The high molecular weight of some anthropogenic pollutants (SO2, O3, NO2, CO2, etc.) would facilitate their segregation along shorter distances compared to those involved in the heterosphere. The simulations indicate that deep wells could concentrate some air components and pollutants by orders of magnitude over the levels at the Earth's surface without external energy input. For instance, argon molar fractions of >40% and >60% could be achievable at 44 km and 55 km depth, respectively. Finally, we discuss the feasibility of gravitational separation as a potential pollution abatement technology.


Assuntos
Poluentes Atmosféricos/análise , Terra (Planeta) , Monitoramento Ambiental/métodos , Gases/análise , Gravitação , Modelos Teóricos , Poluentes Atmosféricos/química , Atmosfera/química , Gases/química , Peso Molecular
16.
J Environ Sci (China) ; 83: 21-38, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31221384

RESUMO

In-situ measurements of aerosol optical properties were conducted at Mt. Huang from September 23 to October 28, 2012. Low averages of 82.2, 10.9, and 14.1 Mm-1 for scattering coefficient (σsp, neph, 550), hemispheric backscattering coefficient (σhbsp, neph, 550), and absorption coefficient (σap, 550), respectively, were obtained. Atmospheric aging process resulted in the increase of σap, 550 but the decrease of the single scattering albedo (ω550) at constant aerosol concentration. However, the proportion of non-light-absorbing components (non-BCs) was getting higher during the aging process, resulting in the increase of aerosol diameter, which also contributed to relatively higher σsp, neph, 550 and ω550. Diurnal cycles of σsp, neph, 550 and σap, 550 with high values in the morning and low values in the afternoon were observed closely related to the development of the planetary boundary layer and the mountain-valley breeze. BC mixing state, represented by the volume fraction of externally mixed BC to total BC (r), was retrieved by using the modified Mie model. The results showed r reduced from about 70% to 50% when the externally mixed non-BCs were considered. The periodical change and different diurnal patterns of r were due to the atmospheric aging and different air sources under different synoptic systems. Local biomass burning emissions were also one of the influencing factors on r. Aerosol radiative forcing for different mixing state were evaluated by a "two-layer-single-wavelength" model, showing the cooling effect of aerosols weakened with BC mixing state changing from external to core-shell mixture.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Fuligem/análise , Aerossóis/análise , Atmosfera/química , China
17.
J Environ Sci (China) ; 83: 217-228, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31221385

RESUMO

The impact of air masses motion on marine aerosol properties was investigated using an on-board single particle mass spectrometer (SPAMS) deployed for the determination of single particle size resolved chemical composition over Southeast China Sea. Two aerosol blooms (E1 and E2) were observed during the cruise. High average particle number count occurred in E1 (7320), followed by E2 (5850), which was more than 100-150 times of the average particle number count during normal periods. Particles were classified as four major sources, including continental source, shipping source, marine source, and transport source based on the mass spectral similarity. Transport source was identified as those particles with high particle number count occurred only during aerosol bloom period. Three sub-types of EC-Ca, OC-Ca, and Al-rich were classified as transport source. EC-Ca was the dominant particles of the transport source, accounting for more than 70% of the total particles in aerosol bloom events. A uni-modal size distribution in the size range of 0.1-2.0 µm was observed during normal period, while a bimodal distribution with a tiny mode (<0.3 µm) and a coarse mode between 0.4 and 0.6 µm was present during aerosol bloom. The variation of aerosol source is consistent with air masses back trajectories, for the reason that most of the long-range air trajectories are from the ocean, while short air trajectories originate in the continental regions, which means that air masses have a significant impact on the aerosol physical-chemical properties along their tracks.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Movimentos do Ar , Poluição do Ar/estatística & dados numéricos , Atmosfera/química , China , Material Particulado/análise
18.
Sci Total Environ ; 685: 96-103, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31174127

RESUMO

Only few studies investigated the input of microplastic particles via the atmosphere, so far. Here, we present results on microplastic concentrations in the atmospheric deposition in the metropolitan region of Hamburg. In total, six investigation sites were equipped with three bulk precipitation samplers each and sampled biweekly over 12 weeks (12/17-03/18). Three sites were located in a rural area south of Hamburg comprising one open field site and two throughfall sites under beech/oak and Douglas fir forest canopy, respectively. Three further sites were selected within the city following a transect from north to south representing urban sites of varying degrees concerning population, traffic and industrial pressures. Particles and fibers were counted under UV light within a photo box and under a fluorescence microscope (Axio Lab A.1, Zeiss). Results show that microplastic particles are ubiquitous at all sites. A median abundance between 136.5 and 512.0 microplastic particles per m2/day has been found over the sampling period. This equals a mean microplastic abundance of 275 particles/m2/day µRaman spectroscopy showed that polyethylenes/ethylvinyl acetate copolymers are dominating significantly (48.8 and 22.0%, respectively), 16 particles analyzed (14.6%) were identified as contamination from PE (polyethylene) samplers. In contrast to other studies, fragments were significantly dominating compared to fibers. The spatial distribution comparing the urban sites concentrations followed in the order from high to low: "north" (Henstedt-Ulzburg, low population density, suburb) - "center" (University; large population density) - "south" (Wilhelmsburg, middle population density, port and industrial facilities) with highly varying concentrations within the time series. Surprisingly, the rural sites in the southern part of Hamburg showed highest concentrations (Douglas fir > open field > beech/oak). This finding is most likely a result of factors such as the comb out capacity of the different forest types and/or direct input pathways from the agricultural areas and the nearby highway.


Assuntos
Poluentes Atmosféricos/análise , Atmosfera/química , Monitoramento Ambiental , Plásticos/análise , Alemanha
19.
Ecotoxicol Environ Saf ; 180: 715-722, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31152985

RESUMO

Elemental mercury (Hg0) is the major form of mercury (Hg) emitted into the environment via anthropogenic activities, resulting in the distribution of Hg worldwide via atmospheric transport. Hg0 in oceans plays an important role in global Hg cycling, mainly by affecting the oceanic-atmospheric exchange of Hg. Due to the large amounts of Hg that are released into Chinese coastal seas from rivers and other sources, Chinese coastal seas are thought to be important sources of Hg in open oceans and in the atmosphere. There have been some studies on the distribution of dissolved gaseous mercury (DGM) in Chinses coastal seas and their controlling factors. However, most of these studies were focused on the surface seawater. There is still a lack of comprehensive study on the DGM through the entire water column in Chinese coastal seas. In this study, two cruises were conducted in August 2017 and in December 2017 to January 2018 to identify the distribution of DGM and its controlling factors in the Yellow Sea (YS) and the Bohai Sea (BS). The concentrations of DGM were higher in summer (167.5 ±â€¯121.4 pg/L) than in winter (41.5 ±â€¯25.5 pg/L), reflecting a significant seasonal variation in DGM. DGM concentrations in the BS and the YS were higher than in open oceans and lower than in some coastal regions. DGM concentrations were generally highest in the BS, followed by the northern YS and the southern YS in summer, whereas the reverse trend was observed in winter. DGM in seawater presented a complicated spatial distribution pattern, with high DGM concentration areas present both nearshore and offshore areas. This result indicates that both terrestrial input and in situ production may play important roles in controlling the DGM distribution. Correlation and multiple regression analyses suggested that temperature (T) and wind speed may be important factors affecting the seasonal variation in DGM in the YS and the BS, and reactive Hg (RHg), dissolved Hg (DHg), dissolved oxygen (DO) and suspended particulate matter (SPM) play important roles in controlling the spatial distribution of DGM.


Assuntos
Gases/análise , Mercúrio/análise , Oceanos e Mares , Água do Mar/química , Poluentes Químicos da Água/análise , Atmosfera/química , Monitoramento Ambiental , Estações do Ano , Temperatura Ambiente , Vento
20.
Radiat Res ; 192(2): 219-230, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31246533

RESUMO

Primary amines form a key component of a well-studied mechanism for capturing carbon dioxide (CO2) from the atmosphere. This study comprises a single-step synthesis of a novel sorbent for CO2 by grafting monomers rich in primary amines to three commercial-grade fabrics: polyethylene terephthalate, high-density polyethylene and nylon 6. An initial evaluation of the sorbency of the chosen monomers, allylamine and butenylamine, qualitatively confirmed their ability to extract CO2 from the atmosphere. Six novel copolymers, comprised of each of the three fabrics grafted with one of each monomer, were synthesized using radiation-induced graft copolymerization through electron beam irradiation. All fabrics achieved greater grafting with butenylamine compared to allylamine, likely given the closer proximity of the primary amine to the radical on the latter's structure. Primary amines can stabilize radicals, preventing copolymerization reactions. Characterization of sorbency revealed that the majority of the grafted amines likely reacted to adsorb CO2. Therefore, the amount of amine grafted comprises the primary limiting factor on the sorbents' CO2 capacity.


Assuntos
Atmosfera/química , Dióxido de Carbono/química , Polimerização , Têxteis , Adsorção , Aminas/química , Técnicas de Química Sintética , Radioquímica
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