scholarly journals Molecular characteristics and diurnal variations of organic aerosols at a rural site in the North China Plain with implications for the influence of regional biomass burning

2019 ◽  
Author(s):  
Jianjun Li ◽  
Gehui Wang ◽  
Qi Zhang ◽  
Jin Li ◽  
Can Wu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Organic Carbon ◽  
Biomass Burning ◽  
North China Plain ◽  
Phthalate Esters ◽  
Rural Site ◽  
Molecular Characteristics ◽  
Air Masses ◽  
The North ◽  
Polycyclic Aromatic

Abstract. Field burning of crop residue in early summer releases into the atmosphere a large amount of pollutants with significant impacts on the air quality and aerosol properties in the North China Plain (NCP). In order to investigate the influence of this regional anthropogenic activity on organic molecular characteristics of aerosol, we collected PM2.5 filter samples every 3 hours at a rural site of NCP during June 10th to 25th, 2013, and analyzed them for more than 100 organic tracer compounds, including both primary (n-alkanes, fatty acids/alcohols, sugar compounds, polycyclic aromatic hydrocarbons, hopanes, and phthalate esters) and secondary (phthalic acids, isoprene-, α-/β-pinene, β-caryophellen-, and toluene-derived products) organic aerosol tracers, as well as for organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC). Total concentrations of the measured organics ranged from 177 to 6248 ng m−3 (mean 1806 ± 1308 ng m−3) during the study period, most of which were contributed by sugar compounds, followed by fatty acids and fatty alcohols. Levoglucosan (240 ± 288 ng m−3) was the most abundant single compound and strongly correlated with OC and WSOC, suggesting that biomass burning (BB) is an important source of summertime organic aerosols in this rural region. Based on analysis of fire spots and backward trajectories of air masses, two representative periods were classified, which are (1) Period 1 (P1), Jun 13th 21:00–16th 15:00, when air masses were uniformly from the southeast part of NCP, where intensified open-field burning of biomass fuels occurred and (2) Period 2 (P2), Jun 22nd 12:00–24th 06:00, which were representative of local emission. Nearly all the measured PM components showed much higher concentrations in P1 than in P2. Although n-alkanes, fatty acids, and fatty alcohols presented similar temporal/diurnal variations as those of levoglucosan throughout the entire period, their molecular distributions were more dominated by high molecular weight (HMW) compounds in P1, demonstrating an enhanced contribution from BB emissions. In contrast, intensified BB emission in P1 seems to have limited influences on the concentrations of polycyclic aromatic hydrocarbons (PAHs), hopenes and phthalate esters. Both 3-hydroxyglutaric acid and β-caryophyllinic acid showed strong linearly correlations with levoglucosan (R2 = 0.72 and 0.80, respectively), indicating that biomass burning is also an important source for terpene-derived SOA formation. A tracer-based method was used to access the distribution of biomass-burning OC, fungal-spore OC and secondary organic carbon (SOC) derived from isoprene, α-/β-pinene, β-caryophyllene, and toluene in the different periods. The results showed that the contribution of biomass- burning OC to total OC in P1 (27.6 %) was 1.7 times of that in P2 (17.1 %). However, the contribution of SOC from oxidation of the four kinds of VOCs increased slightly from 16.3 % in P1 to 21.1 % in P2.

scholarly journals Molecular characteristics and diurnal variations of organic aerosols at a rural site in the North China Plain with implications for the influence of regional biomass burning

2019 ◽  
Vol 19 (16) ◽  
pp. 10481-10496 ◽  
Author(s):  
Jianjun Li ◽  
Gehui Wang ◽  
Qi Zhang ◽  
Jin Li ◽  
Can Wu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Organic Carbon ◽  
Biomass Burning ◽  
Phthalate Esters ◽  
Organic Aerosols ◽  
Rural Site ◽  
Molecular Characteristics ◽  
Air Masses ◽  
The North ◽  
Polycyclic Aromatic

Abstract. Field burning of crop residue in early summer releases a large amount of pollutants into the atmosphere with significant impacts on the air quality and aerosol properties in the North China Plain (NCP). In order to investigate the influence of this regional anthropogenic activity on molecular characteristics of organic aerosols, PM2.5 filter samples were collected with a 3 h interval at a rural site of NCP from 10 to 25 June 2013 and analyzed for more than 100 organic tracer compounds, including both primary (n-alkanes, fatty acids/alcohols, sugar compounds, polycyclic aromatic hydrocarbons, hopanes, and phthalate esters) and secondary organic aerosol (SOA) tracers (phthalic acids, isoprene-, α-/β-pinene, β-caryophyllene, and toluene-derived products), as well as organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC). Total concentrations of the measured organics ranged from 177 to 6248 ng m−3 (mean 1806±1308 ng m−3) during the study period, most of which were contributed by sugar compounds, followed by fatty acids and fatty alcohols. Levoglucosan (240±288 ng m−3) was the most abundant single compound and strongly correlated with OC and WSOC, suggesting that biomass burning (BB) is an important source of summertime organic aerosols in this rural region. Based on the analysis of fire spots and backward trajectories of air masses, two representative periods were classified, which are (1) Period 1 (P1), 13 June 21:00–16 June at 15:00 CST (China Standard Time), when air masses were uniformly distributed from the southeast part of NCP, where intensive open-field biomass burning occurred; and (2) Period 2 (P2), 22 June at 12:00 to 24 June at 06:00 CST, which is representative of local emission. Nearly all the measured PM components showed much higher concentrations in P1 than in P2. Although n-alkanes, fatty acids, and fatty alcohols presented similar temporal–diurnal variations as those of levoglucosan throughout the entire period, their molecular distributions were more dominated by high molecular weight (HMW) compounds in P1, demonstrating an enhanced contribution from BB emissions. In contrast, intensive BB emission in P1 seems to have limited influence on the concentrations of polycyclic aromatic hydrocarbons (PAHs), hopanes, and phthalate esters. Both 3-hydroxyglutaric acid and β-caryophyllinic acid showed strong linearly correlations with levoglucosan (R2=0.72 and 0.80, respectively), indicating that BB is also an important source for terpene-derived SOA formation. A tracer-based method was used to estimate the distributions of biomass-burning OC, fungal-spore OC, and secondary organic carbon (SOC) derived from isoprene, α-/β-pinene, β-caryophyllene, and toluene in the different periods. The results showed that the contribution of biomass-burning OC to total OC in P1 (27.6 %) was 1.7 times that in P2 (17.1 %). However, the contribution of SOC from oxidation of the four kinds of volatile organic compounds (VOCs) increased slightly from 16.3 % in P1 to 21.1 % in P2.

scholarly journals Diurnal variations of organic molecular tracers and stable carbon isotopic composition in atmospheric aerosols over Mt. Tai in the North China Plain: an influence of biomass burning

2012 ◽  
Vol 12 (18) ◽  
pp. 8359-8375 ◽  
Author(s):  
P. Q. Fu ◽  
K. Kawamura ◽  
J. Chen ◽  
J. Li ◽  
Y. L. Sun ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Carbon Isotopic Composition ◽  
Organic Aerosol ◽  
Stable Carbon ◽  
Carbon Isotopic ◽  
The North ◽  
The North China Plain

Abstract. Organic tracer compounds, as well as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and stable carbon isotope ratios (δ13C) of total carbon (TC) have been investigated in aerosol samples collected during early and late periods of the Mount Tai eXperiment 2006 (MTX2006) field campaign in the North China Plain. Total solvent-extractable fractions were investigated by gas chromatography/mass spectrometry. More than 130 organic compounds were detected in the aerosol samples. They were grouped into twelve organic compound classes, including biomass burning tracers, biogenic primary sugars, biogenic secondary organic aerosol (SOA) tracers, and anthropogenic tracers such as phthalates, hopanes and polycyclic aromatic hydrocarbons (PAHs). In early June when the field burning activities of wheat straws in the North China Plain were very active, the total identified organics (2090 ± 1170 ng m−3) were double those in late June (926 ± 574 ng m−3). All the compound classes were more abundant in early June than in late June, except phthalate esters, which were higher in late June. Levoglucosan (88–1210 ng m−3, mean 403 ng m−3) was found as the most abundant single compound in early June, while diisobutyl phthalate was the predominant species in late June. During the biomass-burning period in early June, the diurnal trends of most of the primary and secondary organic aerosol tracers were characterized by the concentration peaks observed at mid-night or in early morning, while in late June most of the organic species peaked in late afternoon. This suggests that smoke plumes from biomass burning can uplift the aerosol particulate matter to a certain altitude, which could be further transported to and encountered the summit of Mt. Tai during nighttime. On the basis of the tracer-based method for the estimation of biomass-burning OC, fungal-spore OC and biogenic secondary organic carbon (SOC), we estimate that an average of 24% (up to 64%) of the OC in the Mt. Tai aerosols was due to biomass burning in early June, followed by the contribution of isoprene SOC (mean 4.3%). In contrast, isoprene SOC was the main contributor (6.6%) to OC, and only 3.0% of the OC was due to biomass burning in late June. In early June, δ13C of TC (−26.6 to −23.2‰, mean −25.0‰) were lower than those (−23.9 to −21.9‰, mean −22.9‰) in late June. In addition, a strong anti-correlation was found between levoglucosan and δ13C values. This study demonstrates that crop-residue burning activities can significantly enhance the organic aerosol loading and alter the organic composition and stable carbon isotopic composition of aerosol particles in the troposphere over the North China Plain.

scholarly journals Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

2016 ◽  
Vol 16 (17) ◽  
pp. 10985-11000 ◽  
Author(s):  
Yin Wang ◽  
Zhongming Chen ◽  
Qinqin Wu ◽  
Hao Liang ◽  
Liubin Huang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Direct Production ◽  
The North ◽  
The North China Plain ◽  
The Impact ◽  
Haze Days

Abstract. Measurements of atmospheric peroxides were made during Wangdu Campaign 2014 at Wangdu, a rural site in the North China Plain (NCP) in summer 2014. The predominant peroxides were detected to be hydrogen peroxide (H2O2), methyl hydroperoxide (MHP) and peroxyacetic acid (PAA). The observed H2O2 reached up to 11.3 ppbv, which was the highest value compared with previous observations in China at summer time. A box model simulation based on the Master Chemical Mechanism and constrained by the simultaneous observations of physical parameters and chemical species was performed to explore the chemical budget of atmospheric peroxides. Photochemical oxidation of alkenes was found to be the major secondary formation pathway of atmospheric peroxides, while contributions from alkanes and aromatics were of minor importance. The comparison of modeled and measured peroxide concentrations revealed an underestimation during biomass burning events and an overestimation on haze days, which were ascribed to the direct production of peroxides from biomass burning and the heterogeneous uptake of peroxides by aerosols, respectively. The strengths of the primary emissions from biomass burning were on the same order of the known secondary production rates of atmospheric peroxides during the biomass burning events. The heterogeneous process on aerosol particles was suggested to be the predominant sink for atmospheric peroxides. The atmospheric lifetime of peroxides on haze days in summer in the NCP was about 2–3 h, which is in good agreement with the laboratory studies. Further comprehensive investigations are necessary to better understand the impact of biomass burning and heterogeneous uptake on the concentration of peroxides in the atmosphere.

scholarly journals Chemical characteristics of PM<sub>2.5</sub>: Impact of biomass burning at an agricultural site of the North China Plain during a season of transition

2020 ◽  
Author(s):  
Linlin Liang ◽  
Guenter Engling ◽  
Chang Liu ◽  
Wanyun Xu ◽  
Xuyan Liu ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Inorganic Ions ◽  
Ambient Air ◽  
Rural Site ◽  
Chemical Components ◽  
Chemical Characteristics ◽  
The North ◽  
The North China Plain

Abstract. Biomass burning (BB) activities are ubiquitous in China, especially in North China, where there is an enormous rural population and winter heating custom. In order to better understand their impacts on aerosol chemical characteristics in rural and agricultural areas of the North China Plain, BB tracers (i.e., levoglucosan (LG), mannosan (MN) and potassium (K+)), as well as other chemical components were quantified at a rural site (Gucheng, GC) from 15 October to 30 November, during a transition heating season, when the field burning of agricultural residues was becoming intense. The measured daily average PM2.5 concentrations of LG, MN and K+ during this study were 0.79 ± 0.75 μg m−3, 0.03 ± 0.03 μg m−3 and 1.52 ± 0.62 μg m−3. Due to the planetary boundary layer development, carbonaceous components and BB tracers showed higher levels at nighttime than daytime, while OM and secondary inorganic ions were enhanced during daytime, likely due to enhanced photochemical activity. An episode with high levels of BB tracers was encountered at the end of October, 2016, with high LG at 4.37 μg m−3. Based on the comparison of chemical components during different BB periods, it appeared that biomass combustion can obviously elevate carbonaceous components levels, whereas there seems to be essentially no effect on secondary inorganic ions in the ambient air. Moreover, the LG / MN ratios in different BB periods were consistent, while the LG / K+ ratio during intensive BB periods was significantly elevated at times, with K+ not increasing as much as LG during intensive BB episodes. This indicated that there were other sources of K+ in the study region, such as fireworks, fertilizer use, or soil resuspension, which don't have variable contributions of K+ during the intensive BB periods; however, local soft wood and vegetation combustion can't be excluded, which have efficient formation of levoglucosan during flaming fires.

scholarly journals Molecular characterization of free tropospheric aerosol collected at the Pico Mountain Observatory: a case study with long range transported biomass burning plumes

2014 ◽  
Vol 14 (17) ◽  
pp. 24753-24810 ◽  
Author(s):  
K. Dzepina ◽  
C. Mazzoleni ◽  
P. Fialho ◽  
S. China ◽  
B. Zhang ◽  
...  
Keyword(s):  
North America ◽  
Organic Carbon ◽  
Molecular Characterization ◽  
Biomass Burning ◽  
North Atlantic ◽  
Air Masses ◽  
The North ◽  
Tropospheric Aerosol ◽  
The North Atlantic

Abstract. Free tropospheric aerosol was sampled at the Pico Mountain Observatory located at 2225 m a.m.s.l. on Pico Island of the Azores archipelago in the North Atlantic. The observatory (38°28'15'' N; 28°24'14'' W) is located ∼3900 km east and downwind of North America, which enables studies of free tropospheric air transported over long distances, mainly from North America. Aerosol samples collected on filters from June to October 2012 were analyzed to characterize organic carbon, elemental carbon and inorganic ion species. The average ambient concentration of aerosol was 0.9 μg m−3; on average organic aerosol contributes the majority of mass (57%), followed by sulfate (21%) and nitrate (17%). Filter-collected aerosol measurements were positively correlated (with an r2 ≥ 0.80) with continuous aerosol measurements of black carbon, aerosol light scattering and number concentration. Water-soluble organic carbon (WSOC) species extracted from two aerosol samples (9/24 and 9/25) collected consecutively during a pollution event were analyzed using ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. FLEXPART retroplume analysis shows the sampled air masses were very aged (average plume age > 12 days). Approximately 4000 molecular formulas were assigned to each of the mass spectra in the range of m/z 100–1000. The majority of the assigned molecular formulas have unsaturated structures with CHO and CHNO elemental compositions. These aged WSOC compounds have an average O / C ratio of ∼0.45, which is relatively low compared to O / C ratios of other aged aerosol and might be the result of evaporation and increased fragmentation during long-range transport. The increase in aerosol loading during the measurement period of 9/24 was linked to biomass burning emissions from North America by FLEXPART retroplume analysis and Moderate Resolution Imaging Spectroradiometer (MODIS) fire counts. This was confirmed with biomass burning markers detected in WSOC species and with the morphology and mixing state of particles as determined by scanning electron microscopy. The presence of markers characteristic of aqueous-phase reactions of biomass burning phenolic species suggests that the aerosol collected at the Pico Mountain Observatory had undergone cloud processing before reaching the site. Finally, the air masses on 9/25 were more aged (∼15 days) and influenced by marine emissions, as indicated by organosulfates and other species characteristic for marine aerosol such as fatty acids. The change in air masses for the two samples was corroborated by the changes in ozone and the non-methane hydrocarbons ethane and propane, morphology of particles, as well as by the FLEXPART retroplume simulations. This manuscript presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at a lower free troposphere remote location in the North Atlantic.

scholarly journals Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

2016 ◽  
Author(s):  
Yin Wang ◽  
Zhongming Chen ◽  
Qinqin Wu ◽  
Hao Liang ◽  
Liubin Huang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Direct Production ◽  
The North ◽  
The North China Plain ◽  
The Impact ◽  
Haze Days

Abstract. Measurements of atmospheric peroxides were made during Wangdu Campaign 2014 at Wangdu, a rural site in the North China Plain (NCP) in summer 2014. The predominant peroxides were detected to be hydrogen peroxide (H2O2), methyl hydroperoxide (MHP) and peroxyacetic acid (PAA). The observed H2O2 reached up to 11.3 ppbv, which was the highest value compared with previous observations in China at summer time. A box model simulation based on the Master Chemical Mechanism and constrained by the simultaneous observations of physical parameters and chemical species was performed to explore the chemical budget of atmospheric peroxides. Photochemical oxidation of alkenes was found to be the major secondary formation pathway of atmospheric peroxides, while contributions from alkanes and aromatics were of minor importance. The comparison of modelled and measured peroxide concentrations revealed an underestimation during biomass burning events and an overestimation on haze days, which were ascribed to the direct production of peroxides from biomass burning and the heterogeneous uptake of peroxides by aerosols, respectively. The strengths of the primary emissions from biomass burning were on the same order of the known secondary production rates of atmospheric peroxides during the biomass burning events. The heterogeneous process on aerosol particles was suggested to be the predominant sink for atmospheric peroxides. The atmospheric lifetime of peroxides on haze days in summer in the NCP was about 2–3 hours, which is in good agreement with the laboratory studies. Further comprehensive investigations are necessary to better understand the impact of biomass burning and heterogeneous uptake on the concentration of peroxides in the atmosphere.

scholarly journals Bioactive Lipids of Seaweeds from the Portuguese North Coast: Health Benefits versus Potential Contamination

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1366
Author(s):  
Cristina Soares ◽  
Sara Sousa ◽  
Susana Machado ◽  
Elsa Vieira ◽  
Ana P. Carvalho ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Saturated Fatty Acids ◽  
Fatty Acid Content ◽  
Total Lipid Content ◽  
Monounsaturated Fatty Acids ◽  
North Coast ◽  
Bioactive Lipids ◽  
The North ◽  
Atherogenicity Index ◽  
Polycyclic Aromatic

The total lipid content and lipidic profile of seaweeds harvested in the North Coast and purchased in Portugal were determined in this paper. The amount of total lipids in the different species of seaweeds varied between 0.7 ± 0.1% (Chondrus crispus) and 3.8 ± 0.6% (Ulva spp.). Regarding the fatty acid content, polyunsaturated fatty acids (PUFA) ranged between 0–35%, with Ulva spp. presenting the highest amount; monounsaturated fatty acids (MUFA) varied between 19 and 67%; and saturated fatty acids (SFA) were predominant in C. crispus (45–78%) and Gracilaria spp. (36–79%). Concerning the nutritional indices, the atherogenicity index (AI) was between 0.4–3.2, the thrombogenicity index (TI) ranged from 0.04 to 1.95, except for Gracilaria spp., which had a TI of 7.6, and the hypocholesterolemic/hypercholesterolemic ratio (HH) values ranged between 0.88–4.21, except for Gracilaria spp., which exhibited values between 0.22–9.26. The n6/n3 ratio was below 1 for most of the species evaluated, except for Ascophyllum nodosum, which presented a higher value, although below 2. Considering the PUFA/SFA ratio, seaweeds presented values between 0.11–1.02. The polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons (AHCs) contamination of seaweeds under study was also quantified, the values found being much lower than the maximum levels recommended for foodstuff.

scholarly journals Measurement report: Chemical characteristics of PM<sub>2.5</sub> during typical biomass burning season at an agricultural site of the North China Plain

2021 ◽  
Vol 21 (4) ◽  
pp. 3181-3192
Author(s):  
Linlin Liang ◽  
Guenter Engling ◽  
Chang Liu ◽  
Wanyun Xu ◽  
Xuyan Liu ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Inorganic Ions ◽  
Northern China ◽  
Ambient Air ◽  
Rural Site ◽  
Biomass Combustion ◽  
Chemical Components ◽  
The North ◽  
Air Temperatures ◽  
Agricultural Site

Abstract. Biomass burning activities are ubiquitous in China, especially in northern China, where there is a large rural population and winter heating custom. Biomass burning tracers (i.e., levoglucosan, mannosan and potassium (K+)), as well as other chemical components, were quantified at a rural site (Gucheng, GC) in northern China from 15 October to 30 November, during a transition heating season, when the field burning of agricultural residue was becoming intense. The measured daily average concentrations of levoglucosan, mannosan and K+ in PM2.5 (particulate matter with aerodynamic diameters less than 2.5 µm) during this study were 0.79 ± 0.75, 0.03 ± 0.03 and 1.52 ± 0.62 µg m−3, respectively. Carbonaceous components and biomass burning tracers showed higher levels during nighttime than daytime, while secondary inorganic ions were enhanced during daytime. An episode with high levels of biomass burning tracers was encountered at the end of October 2016, with high levoglucosan at 4.37 µg m−3. Based on the comparison of chemical components during different biomass burning pollution periods, it appeared that biomass combustion can obviously elevate carbonaceous component levels, whereas there was essentially no effect on secondary inorganic aerosols in the ambient air. Moreover, the levoglucosan / mannosan ratios during different biomass burning pollution periods remained at high values (in the range of 18.3–24.9); however, the levoglucosan / K+ ratio was significantly elevated during the intensive biomass burning pollution period (1.67) when air temperatures were decreasing, which was substantially higher than in other biomass burning periods (averaged at 0.47).

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