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1.
Chemosphere ; 241: 124955, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31604198

RESUMO

Nowadays, atmospheric pollution has a major impact on the human health and the environment, encouraging the development of biomonitors of the air quality over a wide zone. In this study, the relevance of the epiphyte plants Tillandsia usneoides is studied to estimate the transfer of metal(loid)s from a former Zn and Pb mining zone in the Southeast of Spain (Cartagena-La Unión) to the local atmosphere. Biomonitoring was performed by installing plants in 5 sites along a transect from the main mining area to the urban and the coastal zones. An aliquot of plants was collected in every site every 2 months over 1 year. The Tillandsia usneoides have been observed with SEM-EDX, and analysed by ICP-MS to determine trace element concentrations, magnetic susceptibility signals and Zn and Pb isotopes ratios. Results show that atmospheric particles are distributed homogeneously at the plant surface. By comparing elemental contents in Tillandsia usneoides with regard to the values of the geochemical background of the region of Murcia, significant enrichments are observed in the epiphyte plants for Sb, As, Cd, Zn and Pb. The statistical analyses (decentred PCA and PLS) also suggest that the kinetics of dust deposition is slower for the urban and coastal sites compared to the mining sites and highlight an influence of agricultural activities in Cu deposition. The similarity of isotopic compositions (Zn and Pb) between Tillandsia usneoides, soils and atmospheric particles also put in evidence that these plants could be a powerful tool to trace the source of matter in the atmosphere. Finally, this experiment provides new insight to better understand the foliar absorption mechanisms.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Tillandsia/química , Oligoelementos/análise , Poluição do Ar/análise , Atmosfera/análise , Atmosfera/química , Poluição Ambiental/análise , Metais/análise , Mineração , Solo/química , Espanha
2.
Environ Pollut ; 254(Pt A): 112949, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31376599

RESUMO

In this study, various remote sensing data, modeling data and emission inventories were integrated to analyze the tempo-spatial distribution of biomass burning in mainland Southeast Asia and its effects on the local ambient air quality from 2001 to 2016. Land cover changes have been considered in dividing the biomass burning into four types: forest fires, shrubland fires, crop residue burning and other fires. The results show that the monthly average number of fire spots peaked at 34,512 in March and that the monthly variation followed a seasonal pattern, which was closely related to precipitation and farming activities. The four types of biomass burning fires presented different tempo-spatial distributions. Moreover, the monthly Aerosol Optical Depth (AOD), concentration of particulate matter with a diameter less than 2.5 µm (PM2.5) and carbon monoxide (CO) total column also peaked in March with values of 0.62, 45 µg/m3 and 3.25 × 1018 molecules/cm2, respectively. There are significant correlations between the monthly means of AOD (r = 0.74, P < 0.001), PM2.5 concentration (r = 0.88, P < 0.001), and CO total column (r = 0.82, P < 0.001) and the number of fire spots in the fire season. We used Positive Matrix Factorization (PMF) model to resolve the sources of PM2.5 into 3 factors. The result indicated that the largest contribution (48%) to annual average concentration of PM2.5 was from Factor 1 (dominated by biomass burning), followed by 27% from Factor 3 (dominated by anthropogenic emission), and 25% from Factor 2 (long-range transport/local nature source). The annually anthropogenic emission of CO and PM2.5 from 2001 to 2012 and the monthly emission from the Emission Database for Global Atmosphere Research (EDGAR) were consistent with PMF analysis and further prove that biomass burning is the dominant cause of the variation in the local air quality in mainland Southeast Asia.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/estatística & dados numéricos , Monitoramento Ambiental , Aerossóis/análise , Agricultura , Poluição do Ar/análise , Ásia Sudeste , Atmosfera/análise , Biomassa , Fogo , Material Particulado/análise , Estações do Ano , Incêndios Florestais
3.
Geobiology ; 17(6): 579-593, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31436043

RESUMO

Atmospheric oxygen levels control the oxidative side of key biogeochemical cycles and place limits on the development of high-energy metabolisms. Understanding Earth's oxygenation is thus critical to developing a clearer picture of Earth's long-term evolution. However, there is currently vigorous debate about even basic aspects of the timing and pattern of the rise of oxygen. Chemical weathering in the terrestrial environment occurs in contact with the atmosphere, making paleosols potentially ideal archives to track the history of atmospheric O2 levels. Here we present stable chromium isotope data from multiple paleosols that offer snapshots of Earth surface conditions over the last three billion years. The results indicate a secular shift in the oxidative capacity of Earth's surface in the Neoproterozoic and suggest low atmospheric oxygen levels (<1% PAL pO2 ) through the majority of Earth's history. The paleosol record also shows that localized Cr oxidation may have begun as early as the Archean, but efficient, modern-like transport of hexavalent Cr under an O2 -rich atmosphere did not become common until the Neoproterozoic.


Assuntos
Atmosfera/análise , Isótopos do Cromo/análise , Oxigênio/análise , Solo/química , Isótopos do Cromo/química , Ontário , Oxirredução , Paleontologia , África do Sul , Estados Unidos
4.
Environ Pollut ; 254(Pt A): 113018, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31419659

RESUMO

Thermal desorption (TD) is a universal solvent-free pre-concentration technique. It is often used to pre-concentrate semi-volatile and volatile organic compounds in various sample types. Polycyclic aromatic hydrocarbons (PAHs) are widespread contaminants from incomplete combustion of organic matter and fossil fuel, which have carcinogenic effects on human health. Conventional methods for determining PAHs, represented by solvent extraction, are gradually being replaced by solvent-free methods, typically the TD technique, because of TD's many advantages, including time savings and environmentally friendly treatment. This work presents an extensive review of the universal methods used to determine PAHs in the atmosphere based on the TD technique. The methods currently used for collection and detection of both gas- and particle-phase PAHs in the air are critically reviewed. In addition, the operating parameters of the TD unit are summarized and discussed. The design shortcomings of existing studies and the problems that researchers should address are presented, and promising alternatives are suggested. This paper also discusses important parameters, such as reproducibility and limit of detection, that form a crucial part of quality assurance. Finally, the limitations and the future prospects of the TD technique for use in airborne PAH analyses are addressed. This is the first review of the latest developments of the TD technique for analysis of PAHs and their derivatives in the atmosphere.


Assuntos
Modelos Químicos , Hidrocarbonetos Policíclicos Aromáticos/química , Atmosfera/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos , Hidrocarbonetos Policíclicos Aromáticos/análise , Reprodutibilidade dos Testes
5.
Chemosphere ; 237: 124499, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31401431

RESUMO

Urban trees are a new tool for pollutant monitoring since gaseous and particulate pollutants can deposit in its barks. Polycyclic aromatic hydrocarbons (PAHs) levels were determined in gaseous phase samples collected in polyurethane foam (PUF), total suspended particles (TSP) samples collected in quartz fiber filters and tree bark samples (Tipuana and Sibipiruna) collected in the surroundings of an industrial complex in the metropolitan area of São Paulo. Benzo(b)fluoranthene presented the highest average concentration in the TSP samples and phenanthrene, the highest average concentration in the PUF samples; the sum of carcinogenic equivalents for benzo(a)pyrene (BaPEq) for both phases was above 20 ng m-3, representing a high cancer risk. The most abundant PAH for tree barks was fluoranthene; low weight PAHs presented a higher abundance than the observed in TSP. Coronene (vehicular exhaust marker) presented good correlations with fluoranthene in the tree bark samples, suggesting an influence of vehicular emissions. A tree bark sample collected near the petrochemical area presented biomarkers of petrogenic origin (hopanoids) in the mass spectrum and an unresolved complex mixture (UCM) profile. The results suggested an influence of both vehicular and industrial sources on the air quality observed in the atmosphere and tree barks samples.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Casca de Planta/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluição do Ar , Atmosfera/análise , Brasil , Carcinógenos/análise , Carvão Mineral , Poeira , Fluorenos , Gases , Humanos , Material Particulado/análise , Fenantrenos , Compostos Policíclicos , Emissões de Veículos/análise
6.
J Sci Food Agric ; 99(13): 5962-5968, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31215022

RESUMO

BACKGROUND: Cadra (=Ephestia) cautella (Walker) is a serious cosmopolitan pest that can feed on a wide variety of stored foods. It is controlled mainly by fumigation with phosphine, to which strong resistance has been documented in major stored-product insects in many countries. The need for reliable, user- and environmentally friendly alternatives is therefore high on the agenda to avoid the development of potential resistance and to reduce human exposure to toxic insecticides. Two modified atmospheres (MAs) composed of high carbon dioxide (CO2 ) and low oxygen (O2 ) (90% and 96% CO2 in air) were studied at the laboratory at 20 °C and 65 ± 3% relative humidity (RH) against C. cautella. RESULTS: Eggs (1, 2, and 3 days old), young and mature larvae (10 and 20 days old), pupae (1, 2 and 3 days old) and adults (1 day old) were exposed to two MAs consisting of high CO2 and low O2 for the range of 2 to 104 h. Eggs, old larvae, and pupae were found to be the most tolerant. Adults were rather easily killed and young larvae were the most susceptible. Lethal exposure time (LT99 ) values were between 11.74 h and 128.97 h. CONCLUSION: Modified atmospheres consisting of high CO2 and low O2 offer an affordable combination to control C. cautella effectively. From the perspective of economics and efficacy, 90% CO2 might be the concentration of choice. © 2019 Society of Chemical Industry.


Assuntos
Dióxido de Carbono/farmacologia , Controle de Insetos/métodos , Mariposas/efeitos dos fármacos , Animais , Atmosfera/análise , Dióxido de Carbono/análise , Controle de Insetos/instrumentação , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Mariposas/crescimento & desenvolvimento , Oxigênio/análise , Pupa/efeitos dos fármacos , Pupa/crescimento & desenvolvimento
7.
Environ Monit Assess ; 191(7): 431, 2019 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-31190191

RESUMO

Anthropogenic 106Ru has been detected in the environment from late September to early October 2017 by several European environmental radiological monitoring networks. The paper presents the comprehensive evaluation of Hungarian monitoring results related to the occurrence of 106Ru in various environmental compartments (airborne particulates, deposition, plants, and terrestrial indicators), which was implemented to determine the temporal and spatial variation of the contaminant on a national scale and also to verify the findings based on the data arising from environmental monitoring at a local scale in Budapest. Difficulties in direct comparison of the diverse reported data were also considered; results arising from varied sampling periods were corrected with account taken of the relation between the sampling duration and 4-day-long plume residence (estimation based on the daily monitoring of air and backward trajectory analysis). Integrated analysis of air and deposition measurements and meteorological data was also performed; the deposition processes were investigated by establishing the correlations of activity concentrations measured in the atmosphere and in the deposition samples. In order to study the temporal distribution and spatial localization of the 106Ru contamination and to interpret the measurements at ground level, backward trajectory analysis was performed with HYSPLIT model. The backward trajectory simulations suggested that the release had probably occurred during the last week of September 2017 from the geographical area between Volga and the Urals. In addition, assessment of the doses due to the 106Ru release was implemented considering external exposure from cloudshine and groundshine and internal exposure via inhalation.


Assuntos
Poluentes Atmosféricos/análise , Atmosfera/análise , Monitoramento de Radiação/métodos , Radioisótopos de Rutênio/análise , Hungria , Estações do Ano , Análise Espaço-Temporal
8.
Chemosphere ; 234: 608-617, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31229722

RESUMO

Single particle aerosol mass spectrometry (SPAMS) and Cavity ring-down aerosol extinction albedo spectroscopy (CRD-EAS) were applied in this work to real-time investigate the chemical and physical characteristics of the homogeneous and heterogeneous reactions of O3 with pyrene in a Teflon reaction chamber. Suspended pyrene coated polystyrene latex spheres (PSLs) were generated by vaporization-condensation. Ozonation products and particle size distribution during the reactions were detected in real-time using a SPAMS instrument. Among these products, the peaks at m/z of 262 and 278, assigned to 4,5,9,10-dipyrenequinone and 1-hydroxy-4,5,9,10-dipyrenequinone, respectively, were first detected to our knowledge. The mechanism for the formation of reaction product was also proposed based on the real time monitoring. With increasing the ozone concentration, the size growth of the original pyrene-coated particles and the formation of new fine particles and size growth were observed continuously. The optical characteristics were also investigated using a laboratory-developed CRD-EAS instrument. The extinction and scattering coefficients were observed to increase approximately five and four times, respectively. The absorption coefficient also increased because more polar oxidation products coated on the particles exhibiting higher light absorption ability than pyrene, and meanwhile, the single scattering albedo reduced from 0.88 to 0.77 which indicated the reactions could cause positive climate forcing. Using the on-line mass spectrometry and optic spectroscopy instruments, a systematic analysis method was developed to characterize the chemical and physical properties of homogeneous and heterogeneous reactions in real-time, which will help to investigate and understand the formation of new particles and particle growth in the atmosphere.


Assuntos
Atmosfera/química , Espectrometria de Massas/métodos , Ozônio/química , Pirenos/química , Análise Espectral/métodos , Aerossóis/análise , Poluentes Atmosféricos/análise , Atmosfera/análise , Tamanho da Partícula , Poliestirenos/química
9.
Environ Pollut ; 251: 380-389, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31096142

RESUMO

Atmospheric stability significantly influences the accumulation and dispersion of air pollutants in the near-surface atmosphere, yet few stability metrics have been applied as predictors in statistical PM2.5 concentration mapping practices. In this study, eleven stability metrics were derived from radiosonde soundings collected in eastern China for the time period of 2015-2018 and then applied as independent predictors to explore their potential in favoring the prediction of PM2.5. The statistical results show that the in situ PM2.5 concentration measurements correlated well with these stability metrics, especially at monthly and seasonal timescales. In contrast, correlations at the daily timescale differed markedly between stability metric and also varied with seasons. Nevertheless, the modeling results indicate that incorporating these stability metrics into the PM2.5 modeling framework rendered small contribution to PM2.5 prediction accuracy, yielding an increase of R2 by < 5% and a reduction of RMSE by < 1 µg/m3 on average. Compared with other stability indices, the inversion depth and intensity appeared to have relative larger benefiting potential. In general, our findings indicate that including these stability metrics would not result in significant contribution to the PM2.5 prediction accuracy in eastern China since their effects could be partially overwhelmed or offset by other predictors such as AOD and boundary layer height.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Atmosfera/análise , Monitoramento Ambiental/métodos , Modelos Estatísticos , Material Particulado/análise , China , Monitoramento Ambiental/instrumentação , Tamanho da Partícula , Estações do Ano
10.
Environ Sci Pollut Res Int ; 26(18): 18411-18420, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31049860

RESUMO

Oxidation flow reactors (OFRs) are increasingly used to study the formation and evolution of secondary organic aerosols (SOA) in the atmosphere. The OH/HO2 and OH/O3 ratios in OFRs are similar to tropospheric ratios. In the present work, we investigated the production of SOA generated by OH oxydation and ozonolysis of limonene in OFR as a function of OH exposure and O3 exposure. The results are compared with those obtained from the simulation chambers. The precursor gas is exposed to OH concentrations ranging from 2.11 × 108 to 1.91 × 109 molec cm-3, with an estimated exposure time in the OFR of 137 s. In the environmental chambers, the precursor was oxidized using OH concentrations between 2.10 × 106 and 2.12 × 107 molec cm-3 over exposure times of several hours. In the overlapping OH exposure region, the highest SOA yields are obtained in the OFR, which is explained by the ozonolysis of limonene in the OFR. However, the yields decrease with the increase of OHexp in both systems.


Assuntos
Aerossóis/análise , Limoneno , Modelos Teóricos , Raios Ultravioleta , Compostos Orgânicos Voláteis/análise , Atmosfera/análise , Desenho de Equipamento , Radical Hidroxila/química , Limoneno/química , Limoneno/efeitos da radiação , Oxirredução , Ozônio/química , Processos Fotoquímicos
11.
Environ Pollut ; 249: 831-842, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30953945

RESUMO

Oxygenated volatile organic compounds (OVOCs) are critical atmospheric ozone and secondary organic aerosol (SOA) precursors and radical sources, while understanding of OVOC sources in the atmosphere, especially with large anthropogenic emissions, still has large uncertainties. A high-sensitivity proton transfer reaction mass spectrometer (PTR-MS) was deployed in vastly different atmospheres in southern China, including an urban site (SZ-U), a regional site (NA-R), and a background site (NL-B). Four critical OVOCs, i.e., methanol, acetone, methyl ethyl ketone (MEK) and acetaldehyde, five groups of aromatic hydrocarbons, isoprene and acetonitrile were measured with a high time resolution. The featured relative abundance and diurnal variations of the OVOCs indicated that methanol, acetone and MEK had prominent contributions from urban industrial activities, while acetaldehyde was closely related to the photochemical formation at all three sites. The photochemical age-based parameterization method was improved locally and then applied to quantify different sources of daytime OVOCs: anthropogenic secondary and biogenic sources (together 60-73%) were always the dominant source for acetaldehyde in various atmospheres; in addition to a significant background for methanol, acetone and MEK, anthropogenic primary emissions (mostly industrial) were their dominant source at SZ-U (38-73%), while biogenic sources played the key role for them at NL-B (30-43%); biomass burning contributed a small fraction of 5-17% for the four OVOCs at the three sites.


Assuntos
Poluentes Atmosféricos/análise , Atmosfera/análise , Compostos Orgânicos Voláteis/análise , Atmosfera/química , China , Monitoramento Ambiental , Atividades Humanas , Desenvolvimento Industrial , Processos Fotoquímicos
13.
Chemosphere ; 224: 786-795, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30851530

RESUMO

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous atmospheric pollutants of high concern for public health. In the atmosphere they undergo oxidation, mainly through reactions with ·OH and NOx to produce nitro- and oxygenated (oxy-) derivatives. In this study, we developed a new method for the detection of particle-bound PAHs, nitro-PAHs and oxy-PAHs using direct infusion into an atmospheric pressure photoionisation high-resolution mass spectrometer (APPI-HRMS). Method optimisation was done by testing different source temperatures, gas flow rates, mobile phases and dopants. Samples were extracted with methanol, concentrated by evaporation and directly infused in the APPI source after adding toluene as dopant. Acquisition was performed in both polarity modes. The method was applied to target analysis of seasonal PM2.5 samples from an urban background site in Padua (Italy), in the Po Valley, in which a series of PAHs, nitro- and oxy-PAHs were detected. APPI-HRMS was then used for non-target analysis of seasonal PM2.5 samples and results compared with nano-electrospray ionisation (nanoESI) HRMS. The results showed that, when samples were characterised by highly oxidised organic compounds, including S-containing compounds, like in summer samples, APPI did not bring any additional information with respect to nanoESI in negative polarity (nanoESI(-)). Conversely, for winter samples, APPI(-) could detect a series of aromatic and poly-aromatic compounds, mainly oxidised and nitrogenated aromatics, that were not otherwise detected with nanoESI.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Espectrometria de Massas/métodos , Material Particulado/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Atmosfera/análise , Pressão Atmosférica , Itália
14.
Chemosphere ; 224: 668-679, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30849628

RESUMO

The northwestern Pacific Ocean including the Sea of Japan and the Sea of Okhotsk is one of the least studied regions in terms of mercury behavior and distribution in the sea-atmosphere system. In August and September 2017, we determined gaseous elemental mercury (Hg(0)) in the surface air over this water areas along a 12,000 km cruise. Concentrations varied from 1.07 to 2.74 ng m-3, with an average value of 1,68 ±â€¯0.23 ng m-3 (N = 1853). The average concentrations for the Sea of Japan, the Sea of Okhotsk and the Kuril-Kamchatka sector of the Pacific Ocean were 1.61 ng m-3, 1.71 ng m-3 and 1.61 ng m-3, respectively. The maximum concentrations were observed in the Sea of Okhotsk during periods when air masses arrived from the southern and central Kuril Islands. We believe that the reason for that was volcanic activity. The minimum concentrations were registered in air masses arriving from the northeastern Russia and from open sea areas. In the Sea of Okhotsk we measured Hg(0) concentrations near the cyclone eye and did not register any increase due to increased turbulence. This fact contradicts the previously expressed hypothesis that a strong turbulence above the sea surface causes enhanced Hg(0) concentrations in the air. Apparently there are additional or completely different influencing factors which could provide such increase. Also we found that the diurnal Hg(0) cycle in the Sea of Japan was the opposite of the diurnal Hg(0) cycle in the Sea of Okhotsk.


Assuntos
Poluentes Atmosféricos/análise , Atmosfera/análise , Mercúrio/análise , Tempestades Ciclônicas , Monitoramento Ambiental/métodos , Japão , Oceanos e Mares , Oceano Pacífico , Federação Russa , Erupções Vulcânicas
15.
Environ Pollut ; 247: 515-523, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30708313

RESUMO

Size-resolved samples were collected using a 14-stage impactor during four seasons in Zhengzhou and analyzed for 26 elements to calculate the health risks from atmospheric particle-bound metals. High concentrations of heavy metals were observed in ultrafine (10.2 (Ni)-66.9 (Cd) ng m-3) or submicrometer (11.4 (Ni)-134 (Pb) ng m-3) mode in winter. Two size-dependent models were used to estimate the deposition of inhaled toxic metals in various regions of the human respiratory system. Results show that heavy metals deposited in the alveolar region ranged from 7.6 (As)-375 (Al) ng m-3 and were almost concentrated in ultrafine and fine modes. Cd (2.2-8.6) may cause accumulative non-carcinogenic health effects on children, and Cr (1.0 × 10-4-2.2 × 10-4) may lead to carcinogenic health risks for nearby residents around the sampling site. The major sources by principal component analysis that contributed to Cr and Cd in ultrafine and fine particles were coal combustion, vehicular and industrial emissions. The atmospheric dry deposition fluxes of Cr and Cd were between 0.7 and 1.9 µg m-2 day-1 calculated by a multi-step method. From the environmental and public health perspective, environmental agencies must control the emission of heavy metals in the atmosphere.


Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar/estatística & dados numéricos , Monitoramento Ambiental , Exposição por Inalação/estatística & dados numéricos , Material Particulado/análise , Atmosfera/análise , Atmosfera/química , Criança , China , Cidades , Carvão Mineral/análise , Poeira/análise , Humanos , Indústrias , Metais Pesados/análise , Estações do Ano
16.
Sci Total Environ ; 666: 285-297, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-30798238

RESUMO

The elevation of atmospheric CO2 is an inevitable trend that would lead to significant impact on the interrelated carbon and nitrogen cycles through microbial activities in the aquatic ecosystem. Eutrophication has become a common trophic state of inland waters throughout the world, but how the elevated CO2 affects N cycles in such eutrophic water with algal bloom, and how vegetative restoration helps to mitigate N2O emission remains unknown. We conducted the experiments to investigate the effects of ambient and elevated atmospheric CO2 (a[CO2], e[CO2]; 400, 800 µmol﹒mol-1) with and without the floating aquatic plant, Eichhornia crassipes (Mart.) Solms, on N-transformation in eutrophic water using the 15N tracer method. The nitrification could be slightly inhibited by e[CO2], due mainly to the competition for dissolved inorganic carbon between algae and nitrifiers. The e[CO2] promoted denitrification and N2O emissions from eutrophic water without growth of plants, leading to aggravation of greenhouse effect and forming a vicious cycle. However, growth of the aquatic plant, Eichhornia crassipes, slightly promoted nitrification, but reduced N2O emissions from eutrophic water under e[CO2] conditions, thereby attenuating the negative effect of e[CO2] on N2O emissions. In the experiment, the N transformation was influenced by many factors such as pH, DO and algae density, except e[CO2] and plant presence. The pH could be regulated through diurnal photosynthesis and respiration of algae and mitigated the acidification of water caused by e[CO2], leading to an appropriate pH range for both nitrifying and denitrifying microbes. Algal respiration at night could consume DO and enhance abundance of denitrifying functional genes (nirK, nosZ) in water, which was also supposed to be a critical factor affecting denitrification and N2O emissions. This study clarifies how the greenhouse effect caused by e[CO2] mediates N biogeochemical cycle in the aquatic ecosystem, and how vegetative restoration mitigates greenhouse gas emission.


Assuntos
Bactérias/metabolismo , Dióxido de Carbono/análise , Eichhornia/crescimento & desenvolvimento , Eutrofização , Água Doce/química , Microalgas/crescimento & desenvolvimento , Ciclo do Nitrogênio , Atmosfera/análise , Microalgas/metabolismo , Isótopos de Nitrogênio/análise
17.
Photochem Photobiol Sci ; 18(3): 747-774, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30810562

RESUMO

Global change influences biogeochemical cycles within and between environmental compartments (i.e., the cryosphere, terrestrial and aquatic ecosystems, and the atmosphere). A major effect of global change on carbon cycling is altered exposure of natural organic matter (NOM) to solar radiation, particularly solar UV radiation. In terrestrial and aquatic ecosystems, NOM is degraded by UV and visible radiation, resulting in the emission of carbon dioxide (CO2) and carbon monoxide, as well as a range of products that can be more easily degraded by microbes (photofacilitation). On land, droughts and land-use change can reduce plant cover causing an increase in exposure of plant litter to solar radiation. The altered transport of soil organic matter from terrestrial to aquatic ecosystems also can enhance exposure of NOM to solar radiation. An increase in emission of CO2 from terrestrial and aquatic ecosystems due to the effects of global warming, such as droughts and thawing of permafrost soils, fuels a positive feedback on global warming. This is also the case for greenhouse gases other than CO2, including methane and nitrous oxide, that are emitted from terrestrial and aquatic ecosystems. These trace gases also have indirect or direct impacts on stratospheric ozone concentrations. The interactive effects of UV radiation and climate change greatly alter the fate of synthetic and biological contaminants. Contaminants are degraded or inactivated by direct and indirect photochemical reactions. The balance between direct and indirect photodegradation or photoinactivation of contaminants is likely to change with future changes in stratospheric ozone, and with changes in runoff of coloured dissolved organic matter due to climate and land-use changes.


Assuntos
Atmosfera/análise , Mudança Climática , Ozônio Estratosférico/análise , Raios Ultravioleta , Animais , Regiões Árticas , Carbono/análise , Dióxido de Carbono/análise , Secas , Ecossistema , Poluentes Ambientais/análise , Água Doce/análise , Aquecimento Global , Efeito Estufa , Gases de Efeito Estufa/análise , Camada de Gelo/química , Recursos Naturais , Oceanos e Mares , Perda de Ozônio , Fotólise , Energia Solar
18.
Artigo em Inglês | MEDLINE | ID: mdl-30717400

RESUMO

This study focuses on the chemical weathering process under the influence of human activities in the Jiulongjiang River basin, which is the most developed and heavily polluted area in southeast China. The average total dissolved solid (TDS) of the river water is 116.6 mg/L and total cation concentration ( TZ + ) is 1.5 meq/L. Calcium and HCO 3 - followed by Na + and SO 4 2 - constitute the main species in river waters. A mass balance based on cations calculation indicated that the silicate weathering (43.3%), carbonate weathering (30.7%), atmospheric (15.6%) and anthropogenic inputs (10.4%) are four reservoirs contributing to the dissolved load. Silicates (SCW) and carbonates (CCW) chemical weathering rates are calculated to be approximately 53.2 ton/km²/a and 15.0 ton/km²/a, respectively. When sulfuric and nitric acid from rainfall affected by human activities are involved in the weathering process, the actual atmospheric CO 2 consumption rates are estimated at 3.7 × 105 mol/km²/a for silicate weathering and 2.2 × 105 mol/km²/a for carbonate weathering. An overestimated carbon sink (17.4 Gg C / a ) is about 27.0% of the CO 2 consumption flux via silicate weathering in the Jiulongjiang River basin, this result shows the strong effects of anthropogenic factors on atmospheric CO 2 level and current and future climate change of earth.


Assuntos
Carbonatos/química , Atividades Humanas , Rios/química , Silicatos/química , Atmosfera/análise , Dióxido de Carbono/análise , Sequestro de Carbono , Carbonatos/análise , China , Monitoramento Ambiental , Silicatos/análise , Tempo (Meteorologia)
19.
Artigo em Inglês | MEDLINE | ID: mdl-30759827

RESUMO

In order to assess polybrominated diphenyl ether (PBDE) atmospheric pollution levels in Xi'an, air samples were collected using a large flow air sampler from July 2008 to April 2013. In total, 134 samples were collected and 12 PBDE congeners were detected. Total PBDE concentrations (both gaseous and particulate phase) were 36.38⁻1054 pg/m³, with an average of 253.2 ± 198.4 pg/m³. BDE-209 was identified as the main PBDE component, with a corresponding concentration of 0.00⁻1041 pg/m³, accounting for 89.4% of total PBDEs. Principal component analysis results showed that PBDEs in Xi'an's atmosphere mainly originated from commercial products containing penta-BDE, octa-BDE, and deca-BDE. The relative natural logarithm for partial pressure (RP) of PBDEs (gaseous phase) was calculated using the Clausius⁻Clapeyron equation. The gas flow trajectories at high, middle, and low RP values were analyzed by applying the backward trajectory model. These data indicated that the difference between trajectory distribution and concentration load on trajectories was huge under different RP values. PBDE concentrations (gaseous phase) weighted trajectory showed that the central and southwestern parts of Henan Province and the northwestern area of Hubei Province exhibited the darkest colors, and the daily average concentration contribution of PBDEs to the receiving point was >9 pg/m³, which indicates that these areas might be the main potential source areas of PBDEs in Xi'an's atmosphere.


Assuntos
Poluentes Atmosféricos/química , Monitoramento Ambiental/métodos , Éteres Difenil Halogenados/química , Atmosfera/análise , China , Poluição Ambiental/análise
20.
Environ Monit Assess ; 191(2): 61, 2019 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-30635730

RESUMO

Concentrations of iodine-129 (129I) and atomic ratios of 129I/127I in livestock (grass and milk), agricultural (cabbage, Japanese radish, and rice), and fishery (flatfish and brown alga) products collected from locations around the first Japanese commercial spent nuclear fuel reprocessing plant in Rokkasho were measured from 2006 to 2016. The actual spent nuclear fuel rods were cut and processed to test the functioning of the plant that discharged controlled amounts of 129I to the atmosphere and coastal seawater during the period from 2006 to 2008 (the "cutting period"). Statistically significant increases in 129I concentration and 129I/127I ratio were observed during the cutting period in livestock products and flatfish. On the other hand, these parameters were statistically comparable during and after the cutting period in the other products. The radiation dose through the ingestion of the maximum 129I concentrations, measured in the different products, was estimated to be in the nanoSievert per year level. This value is much smaller than 1 mSv yr-1, which is the permissible authentic radiation dose for the general public. The 129I levels in the samples, especially in milk and flatfish, are discussed in context of the 129I discharge history from the plant.


Assuntos
Poluentes Radioativos do Ar/análise , Produtos Agrícolas/química , Linguados/metabolismo , Radioisótopos do Iodo/análise , Monitoramento de Radiação , Poluentes Radioativos da Água/análise , Agricultura , Animais , Atmosfera/análise , Brassica/química , Pesqueiros , Japão , Gado/metabolismo , Leite/química , Centrais Nucleares , Oryza/química , Feófitas/química , Poaceae/química , Raphanus/química , Água do Mar/química
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