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1.
J Agric Food Chem ; 67(33): 9335-9343, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31343169

RESUMO

The ability of Debaryomyces hansenii to produce volatile sulfur compounds from sulfur amino acids and the metabolic pathway involved have been studied in seven strains from different food origins. Our results proved that l-methionine is the main precursor for sulfur compound generation. Crucial differences in the sulfur compound profile and amino acid consumption among D. hansenii strains isolated from different food sources were observed. Strains isolated from dry pork sausages displayed the most complex sulfur compound profiles. Sulfur compound production, such as that of methional, could result from chemical reactions or yeast metabolism, while according to this study, thioester methyl thioacetate appeared to be generated by yeast metabolism. No relationship between sulfur compounds production by D. hansenii strains and the expression of genes involved in sulfur amino acid metabolism was found, except for the ATF2 gene in the L1 strain for production of methyl thioacetate. Our results suggest a complex scenario during sulfur compound production by D. hansenii.


Assuntos
Aminoácidos Sulfúricos/metabolismo , Debaromyces/metabolismo , Produtos da Carne/análise , Produtos da Carne/microbiologia , Compostos de Enxofre/metabolismo , Animais , Debaromyces/genética , Alimentos Fermentados/análise , Alimentos Fermentados/microbiologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Compostos de Enxofre/química , Suínos , Volatilização
2.
J Chromatogr A ; 1602: 467-473, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31178161

RESUMO

The detection and analysis of explosives and explosive-related compounds is a heightened priority in recent years for homeland security and counter-terrorism applications. This study aimed to evaluate the use of a commercial Lab-On-a-Chip (LOC) instrument for the analysis of explosive vapours, with the long-term goal of developing a portable instrument for passively detecting explosives in air samples. A simple method to collect explosive vapour residues was developed using a glass vial containing varying amounts of the target explosives (1 mg/mL). Standards were diluted to the desired concentration in 150 µL of acetone to facilitate the evaporation. The top of the vial was covered with a circular 0.5 cm diameter filter paper and exposed to a range of temperatures from 22 °C to 80 °C for 15 min. Following evaporation, the filter paper chads were folded and inserted into the LOC wells containing the separation buffer for the analysis, avoiding any further extraction step. After successfully separating and detecting eight explosives via liquid analysis, three explosives were chosen as targets for the vapour analysis experiments. 1,3,5-Trinitrobenzene (TNB), 2,4,6-Trinitrotoluene (TNT), and 2,4,6-Trinitrophenylmethylnitramine (Tetryl) were successfully separated, detected and identified following the vapour extraction of explosive standards onto filter paper chads. Limits of detection for the liquid analysis were demonstrated to be 2.32 ng for TNB, 2.35 ng for Tetryl, and 3.25 ng for TNT. The minimum detectable mass found for the vapour analysis was 6.03 for TNB, 9.99 ng for TNT, and 14.22 ng for Tetryl. The average recovery from the paper chads was 29% for Tetryl, 47% for TNB, and 75% for TNT (n = 4), comparable with findings from previous studies. Results show that a minimum temperature of 40 °C is necessary to vaporize the compounds using acetone, while the best results were achieved when heating the vial to 80 °C. The use of a filter paper to collect the explosives residues, avoiding any additional extraction step, and the ability to analyze these compounds using a LOC instrument, makes this approach a future alternative method for explosive residues detection in the headspace.


Assuntos
Substâncias Explosivas/análise , Dispositivos Lab-On-A-Chip , Nitratos/análise , Limite de Detecção , Padrões de Referência , Temperatura Ambiente , Volatilização
3.
Ecotoxicol Environ Saf ; 182: 109370, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31254859

RESUMO

Heavy metals, especially gaseous heavy metals, have high toxicity and do harm to human. Heavy metal volatilization characteristics of co-combusted municipal solid wastes (MSW) and sewage sludge (SS) from different mass fraction of MSW and SS, different temperature and different O2 concentration atmosphere was investigated. Performance of calcium-based sorbents was also studied. Volatilization efficiency of As, Cr, Cu, Ni, Pb and Zn in MSW was 100%, 45.89%-66.58%, 75.62%-92.45%, 42.33%-65.70%, 39.25%-68.76% and 53.57%-84.62%, and that in SS was 28.37%-40.75%, 33.78%-43.42%, 46.08%-56.69%, 35.04%-51.52%, 18.54%-44.99% and 14.72%-48.88%. Volatilization efficiency of heavy metals increased as mass fraction of SS in a blend decreased and as temperature increased. Volatilization efficiency of all heavy metals examined decreased as O2 concentration increased at high temperature and that of Cu, Pb and Zn increased as O2 concentration increased at low temperature. CaO, Ca(OH)2 and CaCO3 declined the volatilization of As, Cr, Cu, Ni, and Zn, while enhanced that of Pb. With calcium-based sorbents, volatilization efficiency of As, Cr, Cu, Ni, and Zn decreased from 70.06%, 39.91%, 75.52%, 44.08% and 40.10% to 54.24%, 33.73%, 39.98%, 20.56% and 32.06%, while that of Pb increased from 47.23% to 100%. Fitting formula was set to predict the heavy metals volatilization, and risk evaluation of gaseous heavy metals was exhibited.


Assuntos
Cálcio/química , Poluentes Ambientais/química , Incineração , Metais Pesados/química , Eliminação de Resíduos Líquidos , Adsorção , Poluentes Ambientais/análise , Gases , Humanos , Metais Pesados/análise , Esgotos , Resíduos Sólidos , Volatilização
4.
Chemosphere ; 233: 677-686, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31195272

RESUMO

Wastewater, aeration gas, dewatered sludge, and incineration ash and flue gas (from dewatered sludge) were collected from 9 sewage treatment plants (STPs) located in Saitama Prefecture, Japan, and analyzed for seven cyclic and linear volatile methylsiloxanes (VMSs) namely, D3, D4, D5, D6, L3, L4, and L5. The mass loadings and distribution of VMSs in STPs were estimated based on measured concentrations in liquid, solid, and gaseous samples, including incinerated dewatered sludge. Mass loading of ΣVMS varied widely from 21 kg y-1 to 3740 kg y-1, depending on the volume of wastewater treated in each STP. Mass % of ΣVMS distributed in aeration gas was 15% and that in activated sludge was 78%. Approximately 6.6% of ΣVMS remained in the final effluent. Overall, partitioning onto the activated sludge was the dominant removal mechanism for D4, D5, and D6, whereas volatilization was also an important removal mechanism for D4. Incineration was effective to degrade VMSs in dewatered sludge, with a reduction rate of >99%. Activated carbon treatment removed >99% of VMSs from the aeration gas. In Saitama Prefecture, total emission of ΣVMS via STPs was estimated at 434 kg y-1, 86 kg y-1, and 0.065 kg y-1, to aquatic, atmospheric, and terrestrial environments, respectively, which accounted for 83%, 17%, and 0.01% of the total environmental emissions. Our results indicate that majority of VMSs in dewatered sludge can be removed by incineration and emission of VMSs through incineration ash landfill is negligible.


Assuntos
Siloxanas/análise , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Incineração , Japão , Esgotos , Volatilização , Águas Residuárias
5.
Chemosphere ; 233: 440-451, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31181492

RESUMO

A combination of thermogravimetric analysis and lab-scale fixed bed combustion experiments was carried out to study the thermochemical, kinetic and heavy metals emission behavior during co-combustion of industrial coal slurry (CS) and sewage sludge (SS). The results found that the blends had integrative combustion profiles which reflected both coal slurry and sewage sludge. During co-combustion, the ignition performance of CS could be significantly improved with the addition of SS. Synergetic effects of the co-combustion were observed at lower temperature, while the high-temperature char combustion of the blends was inhibited because of high ash components of SS or formation of inactive alkali metal aluminosilicates. Kinetic analysis confirmed the improve iginition behavior of blends. Both the comprehensive combustibility index S and the activation energy suggested that the blends with 20% SS may have the best promoting effects. Compared with CS, the higher concentration of Cl in SS increased the volatilization ratios of Cu, Zn, As, and Pb. When added CS into SS, the volatilization ratios of arsenic decreased during combustion. The inhibition effects for arsenic during co-combustion might be associated with the capture of arsenic vapors by the new-formed Ca/Al from CS thermal decomposition.


Assuntos
Poluentes Atmosféricos/análise , Carvão Mineral/análise , Incineração/métodos , Metais Pesados/análise , Esgotos/química , Arsênico/análise , Cinza de Carvão/análise , Temperatura Alta , Cinética , Volatilização
6.
Environ Sci Process Impacts ; 21(7): 1184-1192, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31188374

RESUMO

The present study was conducted to examine the potential mechanisms responsible for the distribution of polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivatives (o-PAHs) in size fractionated particles and their environmental implications. Size-fractionated atmospheric particles were collected at urban Shanghai, China and analyzed for 5 PAHs and 6 o-PAHs. The concentrations of particle-bound ∑6o-PAHs (sum of 6 o-PAH congeners, 19.1 ± 4.5 ng m-3) were significantly higher than those of ∑5PAHs (sum of 5 PAHs, 9.5 ± 1.9 ng m-3). The size-fractionated distributions of airborne ∑5PAHs and ∑6o-PAHs displayed bimodal peaks at 0.7-1.1 and 9.0-10.0 µm. Emission sources and volatility were important factors influencing the size distribution of particle-bound 5 PAHs and 6 o-PAHs. The dry deposition fluxes of particle-bound 6 o-PAHs estimated from the measured data (3087 ± 467 ng m-2 d-1) were approximately 2 times higher than those of PAHs (1531 ± 344 ng m-2 d-1), with a total deposition flux of 4618 ± 743 ng m-2 d-1. The relative contributions of particles to dry deposition were also size-dependent, e.g., coarse (aerodynamic diameters (Dp) > 2.1 µm) particles dominated the dry deposition fluxes of PAHs and o-PAHs. These results highlight the significance of providing a comprehensive understanding of particle size distribution of PAHs and o-PAHs and their implication for dry deposition in China.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Oxigênio/química , Material Particulado/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , China , Tamanho da Partícula , Volatilização
7.
Plant Foods Hum Nutr ; 74(3): 370-375, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31222477

RESUMO

The flash vacuum-expansion process (FVE) consists of two stages. In the first, the raw material is heated by a steam flow in a chamber at 101.325 kPa; in the second, the plant material passes into an expansion chamber (2 to 5 kPa), where the disintegration of the tissues occur. The puree obtained from the avocado pulp subjected to the first stage of the process was evaluated sensorial and instrumentally (T1), in the same way the puree obtained from fruits that were subjected to the whole process (T2) was evaluated, these were compared with avocado puree obtained by means of a food processor (control). The parameters shiny, avocado-like, luminosity, stretching and hue are more significant to describe the puree control, while boiled vegetable and homogeneity to describe T1; grainy texture, adhesiveness and fibrous are more significant to describe T2.


Assuntos
Manipulação de Alimentos/métodos , Frutas/química , Persea/química , Preparações de Plantas/normas , Cor , Feminino , Manipulação de Alimentos/instrumentação , Temperatura Alta , Humanos , Masculino , Preparações de Plantas/química , Preparações de Plantas/isolamento & purificação , Paladar , Vácuo , Volatilização
8.
Chemosphere ; 232: 387-395, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31158633

RESUMO

Different countries produce varying amounts of polychlorinated biphenyls (PCBs), have distinct patterns of use, and regulations for treatment and disposal. Therefore, long-term countermeasures require an understanding of historical and future emission trends at the national scale. In this study, we estimate historical PCB emissions from products containing PCBs, unintentional production related thermal processes, and disposal processes for products containing PCBs from 1950 to 2030 in Japan. In addition, in order to validate the results, we estimated PCB concentrations in environmental media using an environmental fate model and a sensitivity analysis was conducted. Our results show that total PCB emissions were approximately 2.6 tons in 2017, which was a dramatic decrease from peak emissions of 68.9 tons in 1970. We suggest that PCB emissions may continue to decrease, reaching 0.707 tons in 2030. This trend might be due to a change in the emission source; it was estimated that the main emission source in past and recent years was volatilization from large products containing PCBs. However, it is predicted that the main emission sources in the future will be unintentional PCB production from thermal processes and volatilization from small untreated products containing PCBs, although the estimation of environmental PCB levels suggested that there might be unknown emission sources. Additionally, the sensitivity analysis indicated that some parameters greatly influenced the estimation of recent and future emissions. In particular, there was no detailed information concerning the applications for PCBs, which potentially had a large influence on the estimation of future emissions.


Assuntos
Poluentes Atmosféricos/análise , Conservação dos Recursos Naturais , Monitoramento Ambiental/métodos , Bifenilos Policlorados/análise , Conservação dos Recursos Naturais/história , Conservação dos Recursos Naturais/tendências , Monitoramento Ambiental/história , História do Século XX , História do Século XXI , Japão , Modelos Teóricos , Volatilização
9.
Bioresour Technol ; 289: 121674, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31247527

RESUMO

The objective of this study is to investigate the pyrolysis and kinetic characteristics of three varieties of the bamboo subfamily via thermogravimetry/Fourier transform infrared spectrometry (TG-FTIR) coupling technologies. The pyrolysis process can be divided into three stages of dehydration, volatilization, and carbonization. TG-FTIR analysis revealed that evolved gas is constituted by CO2, CO, CH4, H2O, NO, NO2, formic acid, HCN, and CO functional groups as major pyrolysis products. The kinetic parameters of pyrolysis were calculated using model-free methods of distributed activation energy (DAEM). With an increase in conversion, the activation energy of each bamboo subfamily exhibited distinct variations. The average values of activation energy for moso bamboo, bambusa multiplex, and black bamboo determined by DAEM were 201.59, 220.49, and 224.47 kJ/mol, respectively. Results of thermodynamic and kinetic analysis indicate that the bamboo subfamily shows great potential as an alternative fuel by pyrolysis.


Assuntos
Poaceae/química , Gases/química , Cinética , Pirólise , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Termogravimetria , Volatilização
10.
Waste Manag ; 87: 204-217, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31109519

RESUMO

This study elucidated complex interactions during the chloride volatilization of heavy metals (Pb, Cu, Zn, Mn, and Cr) from municipal solid waste fly ash by combining thermodynamic and kinetic approaches. Chloride volatilization tests under HCl flow at 900 °C and subsequent rinsing with water achieved almost complete removal of Pb, Zn, and Mn. In contrast, almost 100 % of Cr and ∼40 % of Cu were not removed by either volatilization or rinsing processes. Kinetics indicated that the chlorination of Pb, Zn, and Mn followed a pseudo second order reaction and their apparent activation energies were 96.3, 89.2, and 43.5 kJ/mol, respectively. Further thermodynamic calculation revealed that the components contained in fly ash greatly influenced the chlorination of each heavy metal. Unburned carbon facilitated the chlorination of Pb, Zn, and Mn, while it inhibited Cu chlorination. MgO immobilized Cr and inhibited chlorination. KCl and NaCl promoted Zn and Mn chlorination, respectively. The revealed chloride volatilization behavior and effects of co-existing elements could be useful in the design of high-efficiency recovery process of heavy metals from fly ash and the utilization of residues as raw materials for cement. Furthermore, these findings could guide the realization of a recycling-oriented society in terms of reducing waste disposal.


Assuntos
Metais Pesados , Eliminação de Resíduos , Carbono , Cinza de Carvão , Incineração , Cinética , Material Particulado , Resíduos Sólidos , Termodinâmica , Volatilização
11.
Forensic Sci Int ; 300: 99-105, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31085432

RESUMO

A novel method for detection and visualization of latent DNA using Diamond™ Nucleic Acid Dye (DD) staining has been developed. Applying DD to an object has the real potential to visualize DNA on a substrate from which a DNA profile can be generated, but it is important to determine whether this staining will adversely affect other forensic investigational techniques and vice versa. The aim of this study was to examine the interactions between staining a fingermark to detect DNA and then generate a DNA profile in combination with several standard latent fingermark enhancement methods. Six common fingerprint enhancements processes were chosen; (1) black powder, (2) black magnetic powder, (3) red magnetic powder, (4) white powder, (5) aluminum powder and (6) cyanoacrylate fuming. For all six methods, mark enhancement was carried out before DD staining and vice versa. DD is effective in detection of DNA in the presence of both aluminum and white finger mark powders and DD does not compromise the subsequent detection of ridge patterns if DD is applied first. Whilst magnetic powders could be used to successfully enhance latent fingermarks even after DD had been applied to them, latent DNA could not be observed in the marks irrespective of whether magnetic powder was applied before or after DD treatment. Magnetic powders did not adversely affect the profiling of DNA present in the marks. The application of DD to fingermarks did not adversely affect the enhancement of fingermarks using cyanoacrylate fuming. Whilst fluorescent particles resembling cells stained with DD were observed in marks either post-treated or pre-treated with cyanoacrylate vapor, DNA amplification and profiling was not successful. While it may be important in particular investigations to collect DNA profiles from latent fingermarks with continuous ridges and clear minutiae, the main utility of the technique described here would be in relation to investigations where enhancement has resulted in only partial or smudged marks. The results presented here indicate that if it is desirable to visualize latent DNA on an object but it is also planned to treat the object with cyanoacrylate vapor or magnetic powders then it is important to apply DD first, record the location of DNA and then apply the mark enhancement technique. For aluminum and white powder mark treatments such precautions are not important.


Assuntos
Corantes , DNA/isolamento & purificação , Dermatoglifia , Cianoacrilatos , Impressões Digitais de DNA , Feminino , Humanos , Masculino , Repetições de Microssatélites , Microscopia , Reação em Cadeia da Polimerase , Pós , Tato , Volatilização
12.
Ultrason Sonochem ; 56: 114-124, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31101245

RESUMO

Acoustic droplet vaporization (ADV) has been shown to reduce the partial pressure of oxygen (PO2) in a fluid. The goals of this study were three-fold: 1) to determine the ADV pressure amplitude threshold in fluids that had physiologically relevant values for surface tension, protein concentration, and viscosity; 2) to assess whether these parameters and fluid mixing affect ADV-mediated PO2 reduction; and 3) to assess the feasibility of ADV-mediated PO2 reduction in plasma and whole blood. In vitro ADV experiments were conducted using perfluoropentane droplets (number density: 5 × 106 ±â€¯0.2 × 106/mL) dispersed in fluids (saline, polyvinylpyrrolidone solutions, porcine plasma, or porcine whole blood) that had a physiological range of surface tensions (62-68 mN/m), protein concentrations (0 and 68.7 mg/mL), and viscosities (0.7-4 cP). Droplets were exposed to pulsed ultrasound (5 MHz, 4.25 MPa peak negative pressure) while passing through a 37 °C flow system with inline PO2 sensors. In select experiments, the fluid also passed through mixing channels after ultrasound exposure. Our results revealed that the ADV pressure thresholds were the same for all fluids. Surface tension and protein concentration had no effect on PO2 reduction. Increasing viscosity attenuated PO2 reduction. However, the attenuated effect was absent after fluid mixing. Furthermore, ADV-mediated PO2 reduction in whole blood (30.8 ±â€¯3.2 mmHg) was less than that in a polyvinylpyrrolidone solution (40.2 ±â€¯2.1 mmHg) with equal viscosity. These findings should be considered when planning clinical studies of ADV-mediated PO2 reduction and other biomedical applications of ADV.


Assuntos
Acústica , Materiais Biomiméticos/química , Oxigênio/química , Plasma/metabolismo , Oxigênio/metabolismo , Imagens de Fantasmas , Tensão Superficial , Viscosidade , Volatilização
13.
Food Chem ; 292: 75-80, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31054695

RESUMO

Lipid oxidation is a major contributor to the deterioration of the sensory quality of fat-containing dairy powders. Hydroperoxides are the primary oxidation products from unsaturated fatty-acids that readily yield a complex mixture of volatile organic compounds that can adversely impact product quality and shelf life. Headspace solid-phase microextraction gas-chromatography mass-spectrometry was chosen to quantify thirteen lipid oxidation compounds in whole milk powder encompassing a range of volatilities and chemical classes. A central composite rotatable design (CCD, α = 1.1) based on a 23 factorial table was used with response surface methodology to optimize the HS-SPME parameters; determined at; 45 min extraction time and 43 °C extraction temperature. The significant model terms were found to be extraction temperature (p < 0.05) and the interaction between time and temperature (p < 0.05). Precision, accuracy, LOD and LOQ were determined and the method was validated for whole milk powder.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Lipídeos/química , Leite/química , Microextração em Fase Sólida/métodos , Compostos Orgânicos Voláteis/análise , Animais , Análise de Alimentos/métodos , Limite de Detecção , Lipídeos/análise , Oxirredução , Pós/análise , Pós/química , Reprodutibilidade dos Testes , Volatilização
14.
Ying Yong Sheng Tai Xue Bao ; 30(4): 1278-1286, 2019 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-30994289

RESUMO

To understand the characteristics of ammonia volatilization in Losses Plateau, an experiment was conducted in a typical solar greenhouse involving four treatments. Intermittent ventilation chamber method was used to measure NH3 volatilization over the period of tomato-watermelon rotation. The results showed that nitrogen transformation was rapid in solar greenhouse system. The peak NH3 volatilization rate appeared one to two days after fertilization with the range from 0.26 to 2.02 kg N·hm-2·d-1. The NH3 volatilization lasted for about one week in all treatments. No significant differences were recorded in terms of cumulative NH3 volatilization among all nitrogen fertilizer input treatments. The cumulative NH3 losses further increased about 46.7% in two seasons under the same nitrogen application rate, however when irrigation application was decreased. The average NH3 vola-tilization rate and cumulative NH3 losses in watermelon season were higher compared to tomato season, which might be attributed to high temperature during watermelon season. Soil NH4+-N content, water filled pore space, soil temperature of 0-5 cm layer and air temperature all had extremely significant effect on NH3 volatilization rate, while a negative correlation was observed between soil pH and NH3 volatilization rate. Between the different cropping seasons, the rate of NH3 volatilization and cumulative NH3 losses were different, and decreased with decreases in nitrogen input, while reduced irrigation volume increased NH3 volatilization under the same nitrogen application rate.


Assuntos
Agricultura/métodos , Amônia/análise , Fertilizantes , Nitrogênio/análise , Purificação da Água , China , Citrullus/crescimento & desenvolvimento , Lycopersicon esculentum/crescimento & desenvolvimento , Rotação , Solo , Volatilização
15.
Ying Yong Sheng Tai Xue Bao ; 30(4): 1295-1302, 2019 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-30994291

RESUMO

A field experiment was conducted to examine the effects of controlled-release urea (CRU) application on ammonia (NH3) volatilization, nitrogen (N) use efficiency and fresh ear yield of fresh edible maize. The treatments included one control (CK: no N fertilizer application) and four different band fertilization depths (0, 5, 10, 15 and 20 cm). Results showed that NH3 volatilization from non-fertilization band and planting band mainly occurred in the first two weeks after the fertilization, which lasted for almost a month in the fertilization band. Compared to CK, surface broadcasted CRU (0 cm) significantly increased NH3 volatilization from wide-row non-fertilization band or planting band in field. Soil NH3 volatilization amounts ranged from 3.1 to 25.5 kg N·hm-2 with the different depths of CRU application treatments, accounting for 1.7%-14.2% of total N applied. The cumulative NH3 volatilizations were comparable among the depths of 10, 15 and 20 cm of CRU fertilization treatments, which were significantly decreased by 85.9%-87.8% and 67.0%-71.6% as compared with surface broadcasted CRU and 5 cm of CRU fertilization, respectively. The increases of CRU application depth within a certain extent could increase fresh ear yield, total nitrogen accumulation of plants during milking stage, partial factor productivity, agronomic efficiency and apparent recovery efficiency of nitrogenous fertilizer, and the maximum values of these indices were recorded for 15 cm depth. We concluded that CRU application at 15 cm depth would be the optimal practice in terms of reducing NH3 volatilization and improving N use efficiency of fresh edible maize.


Assuntos
Agricultura/métodos , Amônia/análise , Fertilizantes , Nitrogênio , Preparações de Ação Retardada , Solo , Ureia , Volatilização , Zea mays/crescimento & desenvolvimento
16.
J Chromatogr A ; 1599: 247-252, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31030953

RESUMO

Thermal desorption aerosol gas chromatography (TAG) is an effective tool for in situ analysis of particulate organic molecules. However, the performance of current TAG is limited by the detectability of low volatile compounds and the matrix effect. In this study, a dual-trap TAG system was developed to address these issues. Thermally desorbed effluent is focused by a weakly retained trap (for low volatile compounds) in a 1 m capillary column conditioned in the GC oven, followed by a strongly retained trap (for high volatile compounds). Then, the focused analytes are desorbed in a reverse flow into the GC column for analysis. Detection over a wide volatility range from C10 to C40 n-alkanes is achieved using the dual-trap TAG. We show that it has lower discrimination of injection, better linearity and higher detectability of n-alkanes. The dual-trap TAG was applied for in-situ measurement of ambient fine particles (PM2.5) in Beijing. Repeatable retention time of n-alkanes was demonstrated during a continuous measurement over two weeks.


Assuntos
Cromatografia Gasosa/instrumentação , Monitoramento Ambiental/métodos , Aerossóis/química , Alcanos/análise , Pequim , Temperatura Alta , Material Particulado/análise , Volatilização
17.
Environ Sci Pollut Res Int ; 26(16): 16105-16114, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30972679

RESUMO

To reduce the environmental pollution caused by ammonium paratungstate (APT) production in the Ganzhou area in China, simulated experiments in laboratory and field experiments in cement kilns were performed. The migration characteristics of As in secondary residues (thermometallurgy and hydrometallurgy residues) from APT production in cement kilns were similar, and As in the residues existed in the form of sulfides. When the residues were fed at the kiln inlet, the As in the residues was completely distributed in the clinker after a new mass balance of As was reestablished in a very short time. When the residues were fed at the raw mill, the total input rate of As was far higher than the total output rate. Therefore, a part of As was circulated in the cement kiln, and only a small part of As was distributed in the clinker. In addition, the As concentration in the flue gas and the leaching concentration of As in the clinker were far below the limit value in the Chinese standard. For feeding rates below that are used in the field experiment, co-processing of secondary residues in a cement kiln fed at the kiln inlet is environmentally safe. However, if the secondary residues are consistently fed at the raw mill, the As concentration in the flue gas may gradually increase.


Assuntos
Arsênico/análise , Materiais de Construção , Poluentes Ambientais/análise , Compostos de Tungstênio/análise , Poluentes Atmosféricos/análise , Poluentes Atmosféricos/química , Arsênico/química , China , Poluentes Ambientais/química , Metalurgia , Compostos de Tungstênio/química , Volatilização
18.
Sci Total Environ ; 668: 1175-1182, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31018457

RESUMO

Volatile methylsiloxanes (VMSs) are widely used in various personal-care products and industrial additives and products. This study focused on VMSs exposure in the general population, workers, and the families of workers living in residential and industrial areas of southwestern China. VMSs concentrations in indoor environmental matrices from six industrial facilities were 3.4 × 102 to 9.0 × 102 µg m-3 in gas-phase samples, 4.7 × 102 to 1.5 × 104 µg g-1 in PM2.5 samples, and 2.3 × 102 to 7.2 × 103 µg g-1 in dust samples, which were two to four orders of magnitude higher than the concentrations measured in residential areas. Exposure to VMSs was investigated by analysis of plasma samples from workers in residential and industrial areas for the presence of cyclic (D4-D6) and linear (L3-L16) VMSs. VMSs concentrations in plasma samples ranged from 84 to 2.3 × 102 ng ml-1 in workers, one to two orders of magnitude higher than those in the general population (2.2 ng ml-1). Daily VMSs indoor exposure via inhalation and ingestion in individuals from residential and industrial areas were estimated and assessed under working-time and leisure-time conditions. This study showed that exposure to VMSs in industrial areas is approximately two to four or one to two orders of magnitude higher than that in residential areas during the working- or leisure-time scenario, respectively. Furthermore, the families of workers (the non-occupational group) experienced higher levels of exposure to VMSs in their homes compared with the general population. The ratios of exposure to linear VMSs via PM2.5 inhalation to that via the gas phase ranged from 7.8% to 43.1% in industrial areas. This study suggests that intake of linear VMSs via PM2.5 inhalation should be considered when estimating human exposure to VMSs in areas with high levels of PM2.5 air pollution.


Assuntos
Exposição Ambiental/análise , Exposição Ocupacional/análise , Plasma/química , Siloxanas/análise , Poluição do Ar em Ambientes Fechados/análise , China , Poeira , Monitoramento Ambiental , Humanos , Saúde do Trabalhador , Solo/química , Volatilização
19.
Food Chem ; 289: 603-608, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30955654

RESUMO

Starch in cooked rice affects the volatilization of aroma compounds, due to their interactions. In particular, the linear fraction of starch from various plant sources, i.e. amylose, can form complexes with a wide variety of ligands. In the present work, the capacity of amylose for embedding and controlling the release of five aroma compounds (hexanal, 1-octen-3-ol, γ-decalactone, 2-acetyl-1-pyrroline, 2,3-butanedione), corresponding to the different types of typical aromas in cooked rice, were tested to determine whether they formed complexes with amylose. The results obtained from x-ray diffraction and differential scanning calorimetry showed that the interactions occurred between amylose and aromas, and four of the aromas (except for 2,3-butanedione) could form complexes with V-type crystal. The release behavior of aromas from complexes was further evaluated using gas chromatography, indicating that amylose has effects on aroma release. These findings suggested that interactions between rice amylose and aromas occurred, thus affecting the release of aromas from the amylose matrix.


Assuntos
Amilose/química , Odorantes/análise , Oryza/química , Varredura Diferencial de Calorimetria , Cromatografia Gasosa , Lactonas/química , Pirróis/química , Amido/química , Pressão de Vapor , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Volatilização , Difração de Raios X
20.
Bull Environ Contam Toxicol ; 103(2): 218-224, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31030224

RESUMO

Dissolved gaseous mercury (DGM) production was examined in relation to ultraviolet radiation within a marine aquaculture site in the contaminated Marano and Grado Lagoon (Italy). The measured rates of DGM production relative to time elapsed (17.06 and 20.68 pg h-1, respectively) were substantially (6-20 times) higher than what has been observed in other marine Hg studies. We measured similar levels of DGM relative to dissolved total mercury (THgD) (0.84%-8.91%) at these sites in comparison to uncontaminated marine sites, however relative to other moderately-contaminated marine sites in Portugal the % DGM/THgD was high. These results suggest a substantial capacity for Hg volatilization from these highly contaminated lagoons to the atmosphere due to photoreduction mechanisms.


Assuntos
Aquicultura , Gases/análise , Mercúrio/análise , Poluentes Químicos da Água/análise , Gases/efeitos da radiação , Itália , Mercúrio/efeitos da radiação , Solubilidade , Raios Ultravioleta , Volatilização , Poluentes Químicos da Água/efeitos da radiação
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