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1.
Organic and elemental carbon (OC and EC) content in PM10 was studied at two sites in Prague, which were located in a suburb and in the downtown. Similar overall average levels were found for both species and also for the PM10 mass at the two sites (i.e., 5.5 and 4.8 μg/m3 for OC, 0.74 and 0.80 μg/m3 for EC, and 33 μg/m3 and 37 μg/m3 for the PM10 mass at the suburb and downtown site, respectively), but substantial differences were observed between the two sites in some seasons and/or meteorological situations. Approximately three times higher values were found for OC in winter compared to summer, with a higher winter/summer ratio for the suburban site. The differences for EC were smaller, but still, compared to summer, more than two times higher EC levels were observed during autumn at the suburban site and 1.5 higher EC levels in winter and autumn at the downtown site. The lowest OC to EC ratios at the suburban site were 3.4, while they were around 1.3 for the downtown site. It was found that the origin of the air masses had a major impact on the observed PM10 mass and OC levels, with largest concentrations noted for air masses recirculating over central Europe and arriving from southeastern Europe in winter. Trajectories coming from the west and northwest originating above the Atlantic Ocean and the Artic brought the cleanest air masses to the sites. For EC the largest difference between the two sites was observed for northwesterly winds during the non-heating season when the suburban site was upwind of Prague.  相似文献   

2.
Aerosol size distributions were measured with Micro Orifice Uniform Deposit Impactor (MOUDI) cascade impactors at the rural Angiola and urban Fresno Supersites in California's San Joaquin Valley during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS) winter campaign from December 15, 2000 to February 3, 2001. PM2.5 filter samples were collected concurrently at both sites with Sequential Filter Samplers (SFS). MOUDI nitrate (NO3−) concentrations reached 66 μg/m3 on January 6, 2001 during the 1000–1600 PST (GMT-8) period. Pair-wise comparisons between PM2.5 MOUDI and SFS concentrations revealed high correlations at the Angiola site (r > 0.93) but more variability (r < 0.85) at the Fresno site for NO3−, sulfate (SO4=), and ammonium (NH4+). Correlations were higher at Fresno (r > 0.87) than at Angiola (r < 0.7) for organic carbon (OC), elemental carbon (EC), and total carbon (TC). NO3− and SO4= size distributions in Fresno were multi-modal and wider than the uni-modal distributions observed at Angiola. Geometric mean diameters (GMD) were smaller for OC and EC than for NO3− and SO4= at both sites. OC and EC were more concentrated on the lowest MOUDI stage (0.056 µm) at Angiola than at Fresno. The NO3− GMD increased from 0.97 to 1.02 µm as the NO3− concentration at Angiola increased from 43 to 66 µg m− 3 during a PM2.5 episode from January 4–7, 2001. There was a direct relationship between GMD and NO3− and SO4= concentrations at Angiola but no such relationships for OC or EC. This demonstrates that secondary aerosol formation increases both concentration and particle size for the rural California environment.  相似文献   

3.
The chemical composition of regional background aerosols, and the time variability and sources in the Western Mediterranean are interpreted in this study. To this end 2002–2007 PM speciation data from an European Supersite for Atmospheric Aerosol Research (Montseny, MSY, located 40 km NNE of Barcelona in NE Spain) were evaluated, with these data being considered representative of regional background aerosols in the Western Mediterranean Basin. The mean PM10, PM2.5 and PM1 levels at MSY during 2002–2007 were 16, 14 and 11 µg/m3, respectively. After compiling data on regional background PM speciation from Europe to compare our data, it is evidenced that the Western Mediterranean aerosol is characterised by higher concentrations of crustal material but lower levels of OM + EC and ammonium nitrate than at central European sites. Relatively high PM2.5 concentrations due to the transport of anthropogenic aerosols (mostly carbonaceous and sulphate) from populated coastal areas were recorded, especially during winter anticyclonic episodes and summer midday PM highs (the latter associated with the transport of the breeze and the expansion of the mixing layer). Source apportionment analyses indicated that the major contributors to PM2.5 and PM10 were secondary sulphate, secondary nitrate and crustal material, whereas the higher load of the anthropogenic component in PM2.5 reflects the influence of regional (traffic and industrial) emissions. Levels of mineral, sulphate, sea spray and carbonaceous aerosols were higher in summer, whereas nitrate levels and Cl/Na were higher in winter. A considerably high OC/EC ratio (14 in summer, 10 in winter) was detected, which could be due to a combination of high biogenic emissions of secondary organic aerosol, SOA precursors, ozone levels and insolation, and intensive recirculation of aged air masses. Compared with more locally derived crustal geological dusts, African dust intrusions introduce relatively quartz-poor but clay mineral-rich silicate PM, with more kaolinitic clays from central North Africa in summer, and more smectitic clays from NW Africa in spring.  相似文献   

4.
PM10 samples were collected to characterize the seasonal and annual trends of carbonaceous content in PM10 at an urban site of megacity Delhi, India from January 2010 to December 2017. Organic carbon (OC) and elemental carbon (EC) concentrations were quantified by thermal-optical transmission (TOT) method of PM10 samples collected at Delhi. The average concentrations of PM10, OC, EC and TCA (total carbonaceous aerosol) were 222?±?87 (range: 48.2–583.8 μg m?3), 25.6?±?14.0 (range: 4.2–82.5 μg m?3), 8.7?±?5.8 (range: 0.8–35.6 μg m?3) and 54.7?±?30.6 μg m?3 (range: 8.4–175.2 μg m?3), respectively during entire sampling period. The average secondary organic carbon (SOC) concentration ranged from 2.5–9.1 μg m?3 in PM10, accounting from 14 to 28% of total OC mass concentration of PM10. Significant seasonal variations were recorded in concentrations of PM10, OC, EC and TCA with maxima during winter and minima during monsoon seasons. In the present study, the positive linear trend between OC and EC were recorded during winter (R2?=?0.53), summer (R2?=?0.59) and monsoon (R2?=?0.78) seasons. This behaviour suggests the contribution of similar sources and common atmospheric processes in both the fractions. OC/EC weight ratio suggested that vehicular emissions, fossil fuel combustion and biomass burning could be the major sources of carbonaceous aerosols of PM10 at the megacity Delhi, India. Trajectory analysis indicates that the air mass approches to the sampling site is mainly from Indo Gangetic plain (IGP) region (Uttar Pradesh, Haryana and Punjab etc.), Thar desert, Afghanistan, Pakistan and surrounding areas.  相似文献   

5.
The main objective of this study is to investigate the chemical characteristics of biomass burning aerosol and its impact on regional air quality during an agricultural waste burning period in early summer in the rural areas of Korea. A 12-h integrated intensive sampling of biomass burning aerosol in the fine and coarse modes was conducted on 2–20 June 2003 in Gwangju, Korea. The collected samples were analyzed for concentrations of mass, ionic, elemental, and carbonaceous species. Average concentrations of fine and coarse mass were measured to be 67.9 and 18.7 μg m− 3 during the biomass burning period, 41.9 and 18.8 μg m− 3 during the haze period, and 35.6 and 13.3 μg m− 3 during the normal period, respectively. An exceptionally high PM2.5 concentration of 110.3 μg m− 3 with a PM2.5/PM10 ratio of 0.79 was observed on 6 June 2003 during the biomass burning period. The potassium ratio method was used to identify biomass burning samples. The average ratio of potassium in the fine mode to the coarse mode (FK/CK) was 23.8 during the biomass burning period, 6.0 during the haze period, and 4.7 during the normal period, respectively. A FK/CK ratio above 9.2 was considered a criterion for biomass burning event in this study. Particulate matter from the open field burning of agricultural waste has an adverse impact on visibility, human health, and regional air quality.  相似文献   

6.
Campaigns were conducted to measure Organic Carbon (OC) and Elemental Carbon (EC) in PM2.5 during winter and summer 2003 in Beijing. Modest differences of PM2.5 and PM10 mean concentrations were observed between the winter and summer campaigns. The mean PM2.5/PM10 ratio in both seasons was around 60%, indicating PM2.5 contributed significantly to PM10. The mean concentrations of OC and EC in PM2.5 were 11.2±7.5 and 6.0±5.0μg m-3 for the winter campaign, and 9.4±2.1 and 4.3±3.0 μg m-3 for the summer campaign, respectively. Diurnal concentrations of OC and EC in PM2.5 were found high at night and low during the daytime in winter, and characterized by an obvious minimum in the summer afternoon. The mean OC/EC ratio was 1.87±0.09 for winter and Z39±0.49 for summer. The higher OC/EC ratio in summer indicates some formation of Secondary Organic Carbon (SOC). The estimated SOC was 2.8 μg m-3 for winter and 4.2μg m-3 for summer.  相似文献   

7.
A high-volume cascade impactor, equipped with a PM10 inlet, was used to collect size-segregated aerosol samples during the summer of 2004 at two Portuguese locations: a coastal-rural area (Moitinhos) and an urban area (Oporto). Concentrations of airborne particulate matter (PM), total carbon (TC), organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) were determined for the following particle size ranges: < 0.49, 0.49–0.95, 0.95–3.0, and 3.0–10 µm. The total PM mass concentrations at the urban and coastal-rural sites ranged from 22.8 to 79.6 μg m− 3 and 19.9 to 28.2 μg m− 3, respectively, and more than 56% of the total aerosol mass was found in the fractions below 3.0 μm. At both locations the highest concentrations of OC and EC were found in the submicrometer size range. The regional variability for the OC and EC concentrations, with the highest concentrations being found in the urban area, was related to the contribution of local primary sources (mostly traffic emissions). It was also verified an enrichment of the small size particles in WSOC, representing on average 37.3(± 12.4)% and 59.7(± 18.0)% of OC in the very fine aerosol at the coastal-rural and urban areas, respectively. The amount of secondary OC calculated by the minimum OC/EC ratio method indicates that secondary organic aerosol formation was important throughout the study at both sites. The obtained results suggest that long-range transport and favourable summer conditions for photochemical oxidation are key factors determining secondary OC formation in the coastal-rural and urban areas. The ultraviolet absorption properties of the chromophoric constituents of the WSOC fractions were also different among the different particle size ranges and also between the two sampling locations, thus suggesting the strong impact of the diverse emission sources into the composition of the size-segregated organic aerosol.  相似文献   

8.
Source identification of PM2.5 particles measured in Gwangju, Korea   总被引：1，自引：0，他引：1  
The UNMIX and Chemical Mass Balance (CMB) receptor models were used to investigate sources of PM2.5 aerosols measured between March 2001 and February 2002 in Gwangju, Korea. Measurements of PM2.5 particles were used for the analysis of carbonaceous species (organic (OC) and elemental carbon (EC)) using the thermal manganese dioxide oxidation (TMO) method, the investigation of seven ionic species using ion chromatography (IC), and the analysis of twenty-four metal species using Inductively Coupled Plasma (ICP)-Atomic Emission Spectrometry (AES)/ICP-Mass Spectrometry (MS). According to annual average PM2.5 source apportionment results obtained from CMB calculations, diesel vehicle exhaust was the major contributor, accounting for 33.4% of the measured PM2.5 mass (21.5 μg m− 3), followed by secondary sulfate (14.6%), meat cooking (11.7%), secondary organic carbon (8.9%), secondary nitrate (7.6%), urban dust (5.5%), Asian dust (4.4%), biomass burning (2.8%), sea salt (2.7%), residual oil combustion (2.6%), gasoline vehicle exhaust (1.9%), automobile lead (0.5%), and components of unknown sources (3.4%). Seven PM2.5 sources including diesel vehicles (29.6%), secondary sulfate (17.4%), biomass burning (14.7%), secondary nitrate (12.6%), gasoline vehicles (12.4%), secondary organic carbon (5.8%) and Asian dust (1.9%) were identified from the UNMIX analysis. The annual average source apportionment results from the two models are compared and the reasons for differences are qualitatively discussed for better understanding of PM2.5 sources.Additionally, the impact of air mass pathways on the PM2.5 mass was evaluated using air mass trajectories calculated with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) backward trajectory model. Source contributions to PM2.5 collected during the four air mass patterns and two event periods were calculated with the CMB model and analyzed. Results of source apportionment revealed that the contribution of diesel traffic exhaust (47.0%) in stagnant conditions (S) was much higher than the average contribution of diesel vehicle exhaust (33.4%) during the sampling period. During Asian dust (AD) periods when the air mass passed over the Korean peninsula, Asian dust and secondary organic carbon accounted for 25.2 and 23.0% of the PM2.5 mass, respectively, whereas Asian dust contributed only 10.8% to the PM2.5 mass during the AD event when the air mass passed over the Yellow Sea. The contribution of biomass burning to the PM2.5 mass during the biomass burning (BB) event equaled 63.8%.  相似文献   

9.
The potential resources on the ion-stimulated syntheses effects of aerosol particles of lower troposphere in test sites in the arctic, mountain, arid and forest areas as the function of irradiation time and gas-precursor concentration were experimentally and theoretically evaluated. The dust-free outdoor air was irradiated with an ionization current of 10− 6 A by α-rays from isotope 239Pu. The total output of radiolytic aerosols (RA) with a diameter of 3–1000 nm was found to be 0.05–0.1 molecules per 1 eV of absorbed radiation, while the physical upper limit is 0.25–0.4 molecules/eV. In an interval of exposition time from 6 to 800 s (adsorbed energy is 3 · 1012–1014 eV/cm3) the RA mass concentration at different sites was increased from 1–10 to 50–500 μg/m3. According to the liquid chromatography data the major RA material is the H2O/HNO3 solution with acid concentration  25%. The used physical model presents new aerosols as a product from small and intermediate ion association through formation of neutral clusters and describes adequately some of the peculiarities in field experiment data. Introducing SO2, NH3, and also hydrochloric, nitric and sulphuric acid vapours with concentration 0.1–1 mg/m3 in the irradiated air stimulated an increase of mass aerosol concentration by a factor of 8–30. The mean size also decreased by a factor of 3–5. These facts allowed us to expect that the chemical composition of radiolytic aerosols generated in outdoor air would noticeably differ after addition of the gas-precursors.  相似文献   

10.
Black carbon relationships with emissions and meteorology in Xi'an, China   总被引：4，自引：0，他引：4  
Aerosol black carbon (BC) was measured every 5 min at Xi'an, China from September 2003 to August 2005. Daily BC concentrations ranged from 2 to 65 μg m− 3, averaging 14.7 ± 9.5 μg m− 3 and displayed clear summer minima and winter maxima. BC typically peaked between 0800 and 1000 LST and again between 2000 and 2200 LST, corresponding with morning and evening traffic combined with nighttime residential cooking and heating. The nocturnal peak was especially evident in winter, when more domestic heating is used and pollutant-trapping surface-inversions form earlier than in summer. BC frequency distributions the most commonly occurring concentrations occurred between 5 and 10 μg m− 3 in all four seasons. BC ranged from 1.6% and 15.6%, and averaged 8.3% of PM2.5. A clear inverse relationship between BC and wind speed (WS) was found when WS was below 2.5 to 3.0 m s− 1, implying a local origin for BC. Mixed layer depths (MLDs) were shallower during BC episodes compared to cleaner conditions.  相似文献   

11.

This study presents the chemical composition (carbonaceous and nitrogenous components) of aerosols (PM2.5 and PM10) along with stable isotopic composition (δ13C and δ15N) collected during winter and the summer months of 2015–16 to explore the possible sources of aerosols in megacity Delhi, India. The mean concentrations (mean?±?standard deviation at 1σ) of PM2.5 and PM10 were 223?±?69 µg m?3 and 328?±?65 µg m?3, respectively during winter season whereas the mean concentrations of PM2.5 and PM10 were 147?±?22 µg m?3 and 236?±?61 µg m?3, respectively during summer season. The mean value of δ13C (range: ??26.4 to ??23.4‰) and δ15N (range: 3.3 to 14.4‰) of PM2.5 were ??25.3?±?0.5‰ and 8.9?±?2.1‰, respectively during winter season whereas the mean value of δ13C (range: ??26.7 to ??25.3‰) and δ15N (range: 2.8 to 11.5‰) of PM2.5 were ??26.1?±?0.4‰ and 6.4?±?2.5‰, respectively during the summer season. Comparison of stable C and N isotopic fingerprints of major identical sources suggested that major portion of PM2.5 and PM10 at Delhi were mainly from fossil fuel combustion (FFC), biomass burning (BB) (C-3 and C-4 type vegitation), secondary aerosols (SAs) and road dust (SD). The correlation analysis of δ13C with other C (OC, TC, OC/EC and OC/WSOC) components and δ15N with other N components (TN, NH4+ and NO3?) are also support the source identification of isotopic signatures.

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12.
Haze-fog conditions over northern India are associated with visibility degradation and severe attenuation of solar radiation by airborne particles with various chemical compositions. PM2.5 samples have been collected in Delhi, India from December 2011 to November 2012 and analyzed for carbonaceous and inorganic species. PM10 measurements were made simultaneously such that PM10–2.5 could be estimated by difference. This study analyzes the temporal variation of PM2.5 and carbonaceous particles (CP), focusing on identification of the primary and secondary aerosol emissions, estimations of light extinction coefficient (bext) and the contributions by the major PM2.5 chemical components. The annual mean concentrations of PM2.5, organic carbon (OC), elemental carbon (EC) and PM10–2.5 were found to be 153.6 ± 59.8, 33.5 ± 15.9, 6.9 ± 3.9 and 91.1 ± 99.9 μg m?3, respectively. Total CP, secondary organic aerosols and major anions (e.g., SO4 2? and NO3 ?) maximize during the post-monsoon and winter due to fossil fuel combustion and biomass burning. PM10–2.5 is more abundant during the pre-monsoon and post-monsoon. The OC/EC varies from 2.45 to 9.26 (mean of 5.18 ± 1.47), indicating the influence of multiple combustion sources. The bext exhibits highest values (910 ± 280 and 1221 ± 371 Mm?1) in post-monsoon and winter and lowest in monsoon (363 ± 110 and 457 ± 133 Mm?1) as estimated via the original and revised IMPROVE algorithms, respectively. Organic matter (OM =1.6 × OC) accounts for ~39 % and ~48 % of the bext, followed by (NH4)2SO4 (~21 % and ~24 %) and EC (~13 % and ~10 %), according to the original and revised algorithms, respectively. The bext estimates via the two IMPROVE versions are highly correlated (R2 = 0.95, root mean square error = 38 % and mean bias error = 28 %) and are strongly related to visibility impairment (r = ?0.72), mostly associated with anthropogenic rather than natural PM contributions. Therefore, reduction of CP and precursor gas emissions represents an urgent opportunity for air quality improvement across Delhi.  相似文献   

13.
Ambient concentrations of organic carbon (OC), elemental carbon (EC) and water soluble inorganic ionic components (WSIC) of PM10 were studied at Giridih, Jharkhand, a sub-urban site near the Indo Gangatic Plain (IGP) of India during two consecutive winter seasons (November 2011–February 2012 and November 2012–February 2013). The abundance of carbonaceous and water soluble inorganic species of PM10 was recorded at the study site of Giridih. During winter 2011–12, the average concentrations of PM10, OC, EC and WSIC were 180.2?±?46.4; 37.2?±?6.2; 15.2?±?5.4 and 18.0?±?5.1 μg m?3, respectively. Similar concentrations of PM10, OC, EC and WSIC were also recorded during winter 2012–13. In the present case, a positive linear trend is observed between OC and EC at sampling site of Giridih indicates the coal burning, as well as dispersed coal powder and vehicular emissions may be the source of carbonaceous aerosols. The principal components analysis (PCA) also identifies the contribution of coal burning? +?soil dust, vehicular emissions?+?biomass burning and seconday aerosol to PM10 mass concentration at the study site. Backward trajectoy and potential source contributing function (PSCF) analysis indicated that the aerosols being transported to Giridih from upwind IGP (Punjab, Haryana, Uttar Pradesh and Bihar) and surrounding region.  相似文献   

14.
The changing chemical composition of cloud water and precipitation in the Western Sudety Mountains are discussed against the background of air-pollution changes in the Black Triangle since the 1980s until September 2004. A marked reduction of sulphur dioxide emissions between the early 1990's and the present (from almost 2 million tons to around 0.2 million tons) has been observed, with a substantial decline of sulphate and hydrogen concentration in cloud water (SO42− from more than 200 to around 70 μmol l− 1; H+ from 150 to 50 μmol l− 1) and precipitation (SO42− from around 80 to 20–30 μmol l− 1; H+ from around 60 to 10–15 μmol l− 1) samples. At some sites, where fog/cloud becomes the major source of pollutants, deposition hot spots are still observed where, for example, nitrogen deposition can exceed 20 times the relevant critical load. The results show that monitoring of cloud water chemistry can be a sensitive indicator of pollutant emissions.  相似文献   

15.
The objective of this study was to investigate the correlation of visibility with chemical composition of Kaohsiung aerosols. Daytime visibility was observed around noon at two observation sites in metropolitan Kaohsiung, Taiwan in the years of 1999 and 2000. Both seasonal and diurnal variation patterns of visibility were observed in the region. Ambient aerosols were sampled and analyzed for 11 constituents, including water-soluble ionic species (Cl−, NO3−, SO4−2, NH4+, K+, Na+, Ca+2, and Mg+2) and carbonaceous contents (OC, EC, and TC), to characterize the chemical composition of Kaohsiung aerosols. Furthermore, a stepwise multiple linear regression model was developed to elucidate the influence of aerosol species on visibility impairments. The results showed that sulfate was the dominant species that affected both light scattering coefficient and visibility. On average, the percentage contributions of visibility degrading species to light scattering coefficient were 29% for sulfate, 28% for nitrate, 22% for total carbon, and 21% for PM2.5-remainder. An empirical regression model of visibility based on sulfate, nitrate, and relative humidity was also developed. The model showed that sulfate in PM2.5 was the most sensitive species to visibility variation, suggesting that the reduction of sulfate in PM2.5 could effectively improve the visibility of metropolitan Kaohsiung. During the investigation period, an event of Asian dusts intruded metropolitan Kaohsiung and dramatically increased the aerosol loadings, especially in the coarse particles. However, local visual air quality did not degrade accordingly during the Asian dust event because both visibility and light scattering coefficient are affected mainly by the fine particles. The results are discussed in detail in the paper.  相似文献   

16.

In this study we present the seasonal chemical characteristics and potential sources of PM10 at an urban location of Delhi, India during 2010?2019. The concentrations of carbonaceous aerosols [organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC) and water insoluble organic carbon (WIOC)] and elements (Al, Fe, Ti, Cu, Zn, Mn, Pb, Cr, F, Cl, Br, P, S, K, As, Na, Mg, Ca, B, Ni, Mo, V, Sr, Zr and Rb) in PM10 were estimated to explore their possible sources. The annual average concentration (2010–2019) of PM10 was computed as 227?±?97 µg m?3 with a range of 34?734 µg m?3. The total carbonaceous aerosols in PM10 was accounted for 22.5% of PM10 mass concentration, whereas elements contribution to PM10 was estimated to be 17% of PM10. The statistical analysis of OC vs. EC and OC vs. WSOC of PM10 reveals their common sources (biomass burning and/or fossil fuel combustion) during all the seasons. Enrichment factors (EFs) of the elements and the relationship of Al with other crustal metals (Fe, Ca, Mg and Ti) of PM10 indicates the abundance of mineral dust over Delhi. Principal component analysis (PCA) extracted the five major sources [industrial emission (IE), biomass burning?+?fossil fuel combustion (BB?+?FFC), soil dust, vehicular emissions (VE) and sodium and magnesium salts (SMS)] of PM10 in Delhi, India. Back trajectory and cluster analysis of airmass parcel indicate that the pollutants approaching to Delhi are mainly from Pakistan, IGP region, Arabian Sea and Bay of Bengal.

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17.
Emission of nitrous oxide from temperate forest soils into the atmosphere   总被引：5，自引：0，他引：5  
N2O emission rates were measured during a 13-month period from July 1981 till August 1982 with a frequency of once every two weeks at six different forest sites in the vicinity of Mainz, Germany. The sites were selected on the basis of soil types typical for many of the Central European forest ecosystems. The individual N2O emission rates showed a high degree of temporal and spatial variabilities which, however, were not significantly correlated to variabilities in soil moisture content or soil temperatures. However, the N2O emission rates followed a general seasonal trend with relatively high values during spring and fall. These maxima coincided with relatively high soil moisture contents, but may also have been influenced by the leaf fall in autumn. In addition, there was a brief episode of relatively high N2O emission rates immediately after thawing of the winter snow. The individual N2O emission rates measured during the whole season ranged between 1 and 92 g N2O-N m–2 h–1. The average values were in the range of 3–11 g N2O-N m–2 h–1 and those with a 50% probability were in the range of 2–8 g N2O-N m–2 h–1. The total source strength of temperate forest soils for atmospheric N2O may be in the range of 0.7–1.5 Tg N yr–1.  相似文献   

18.
Zhang  Xiaoyu  Ji  Guixiang  Peng  Xiaowu  Kong  Lingya  Zhao  Xin  Ying  Rongrong  Yin  Wenjun  Xu  Tian  Cheng  Juan  Wang  Lin 《Journal of Atmospheric Chemistry》2022,79(2):101-115

In this study, 123 PM2.5 filter samples were collected in Wuhan, Hubei province from December 2014 to November 2015. Water- soluble inorganic ions (WSIIs), elemental carbon (EC), organic carbon (OC) and inorganic elements were measured. Source apportionment and back trajectory was investigated by the positive matrix factorization (PMF) model and the hybrid single particle lagrangian integrated trajectory (HYSPLIT) model, respectively. The annual PM2.5 concentration was 80.5?±?38.2 μg/m3, with higher PM2.5 in winter and lower in summer. WSIIs, OC, EC, as well as elements contributed 46.8%, 14.8%, 6.7% and 8% to PM2.5 mass concentration, respectively. SO42?, NO3? and NH4+ were the dominant components, accounting for 40.2% of PM2.5 concentrations. S, K, Cl, Ba, Fe, Ca and I were the main inorganic elements, and accounted for 65.2% of the elemental composition. The ratio of NO3?/SO42? was 0.86?±?0.72, indicating that stationary sources play dominant role on PM2.5 concentration. The ratio of OC/EC was 2.9?±?1.4, suggesting the existence of secondary organic carbon (SOC). Five sources were identified using PMF model, which included secondary inorganic aerosols (SIA), coal combustion, industry, vehicle emission, fugitive dust. SIA, coal combustion, as well as industry were the dominant contributors to PM2.5 pollution, accounting for 34.7%, 20.5%, 19.6%, respectively.

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19.
Seasonal variation of PM10-bound PAHs in the atmosphere of Xiamen, China   总被引：3，自引：0，他引：3  
PM10 samples from a garden site (site A), an industrial-traffic intersection (site B), a residential site (site C) and an island site (site D) were collected at December 21–29, 2004; March 18–22, 2005; July 4–13, 2005 and October 24–28, 2005 in Xiamen. 15 priority PAHs compounds were analyzed by using a gas chromatograph/mass spectrometer (GC/MS). The abundance and origin of PAHs are discussed to reveal seasonal variations in Xiamen air quality. Average concentrations of Σ15PAHs were 17.5 ng/m3, 3.7 ng/m3, 32.6 ng/m3 and 10.5 ng/m3 from spring to winter with the highest value in autumn. The dominant PAHs components in every season were low and middle molecular weight PAHs including phenanthrene, pyrene, fluoranthene and chrysene. Diagnostic ratios and PCA analysis identified the main sources of particle bound PAHs: mainly from both gasoline and diesel vehicles exhaust, with some contribution from coal combustion, industry emission and cooking sources.  相似文献   

20.
Summary Daily sampling of atmospheric PM10 particulate was carried out using a continuously weighing, Tapered Element Oscillating Microbalance (TEOM) equipped with a PM10 size selective inlet. The TEOM collects PM10 on a small filter interfaced with an inertial mass transducer, which allows near continuous weighing of the filter as the deposit accumulates. The sampler was sited at several urban and sub-urban places in Córdoba City, Argentina. With the complete data set of chemical and meteorological variables (CO, NOx, O3, wind speed, wind direction, ambient temperature, total and UV radiation, pressure and relative humidity, etc.) a stepwise regression was performed to select which variables have a major influence on the amount of PM10 measured. Results are presented from the June 1995–May 1996 field campaign. Data for PM10 values largely exceeded the one day standard average value of 150 g m–3 during several days. The largest amount of particulate has been measured during the winter season. The primary aim of this work is to define the concentration characteristics of ambient PM10 at each site where this pollutant has been measured and to examine the seasonal variation of PM10.With 3 Figures  相似文献   

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