scholarly journals Measurement report: Ambient volatile organic compounds (VOCs) pollution at urban Beijing: characteristics, sources, and implications for pollution control

2021 ◽  
Author(s):  
Lulu Cui ◽  
Di Wu ◽  
Shuxiao Wang ◽  
Qingcheng Xu ◽  
Ruolan Hu ◽  
...  
Keyword(s):  
Air Pollution ◽  
Organic Compounds ◽  
Pollution Control ◽  
Matrix Factorization ◽  
Diesel Exhaust ◽  
Sampling Period ◽  
Control Measures ◽  
Biomass Combustion ◽  
Positive Matrix ◽  
Volatile Organic

Abstract. The increasing ozone (O3) pollution and high fraction of secondary organic aerosols (SOA) in fine particle mass highlighted the importance of volatile organic compounds (VOCs) in air pollution control. In this work, a campaign of comprehensive field observations was conducted at an urban site in Beijing, from December 2018 to November 2019, to identify the composition, sources, and secondary transformation potential of VOCs. The total mixing ratio of the 95 quantified VOCs (TVOC) observed in this study ranged from 5.5–118.7 ppbv with the mean value of 34.9 ppbv, and the contemporaneous mixing ratios of TVOC was significantly lower than those observed in 2014 and 2016, confirming the effectiveness of VOCs emission control measures in Beijing in recent years. Alkanes, OVOCs and halocarbons were the dominant chemical groups, accounting for 75–81 % of the TVOCs across the sampling months. High and low-O3/PM2.5 months as well as several O3/PM2.5 polluted days were identified during the sampling period. By deweathered calculation, we found that high O3/PM2.5 levels were due to both enhanced precursor emission levels and meteorological conditions favorable to O3 and PM2.5 production. The molar ratios of VOCs to NOX indicated that O3 formation was limited by VOCs during the whole sampling period. Diesel exhaust and industrial emission were identified as the major VOCs sources on both O3-polluted and PM2.5-polluted days based on positive matrix factorization (PMF) analysis, accounting for 46 % and 53 %, respectively. Moreover, higher proportion of oil/gas evaporation was observed on O3-polluted days (18 %) than that on O3-clean days (13 %), and higher proportion of coal/biomass combustion was observed on PM2.5-polluted days (18 %) than that on PM2.5-clean days (13 %). On the base of O3 formation impact, VOCs from fuel evaporation and diesel exhaust particularly toluene, xylenes, trans-2-butene, acrolein, methyl methacrylate, vinyl acetate, 1-butene and 1-hexene were the main contributors, illustrating the necessity of conducting emission controls on these pollution sources and species for alleviating O3 pollution. Instead, VOCs from diesel exhaust and coal/biomass combustion were found to be the dominant contributors for secondary organic aerosol formation potential (SOAFP), particularly the VOC species of toluene, 1-hexene, xylenes, ethylbenzene and styrene, and top priority should be given to these for the alleviation of haze pollution. The positive matrix factorization (PSCF) analysis showed that O3 and PM2.5 pollution was mainly affected by local emissions. This study provides insights for government to formulate effective VOCs control measures for air pollution in Beijing.

scholarly journals VOC source apportionment and emission inventory evaluation over the great Athens, comparison with other cities of the Mediterranean basin

2019 ◽  
Author(s):  
Αναστασία Πανοπούλου
Keyword(s):  
Volatile Organic Compounds ◽  
Source Apportionment ◽  
Organic Compounds ◽  
Matrix Factorization ◽  
Mediterranean Basin ◽  
Emission Inventory ◽  
Positive Matrix Factorization ◽  
Positive Matrix ◽  
Volatile Organic ◽  
The Mediterranean Basin

Παρά τις πρωτοβουλίες για τον περιορισμό και μείωση των ατμοσφαιρικών ρύπων, στη Μεσόγειο και τις πόλεις που την περιβάλλουν εξακολουθούν να καταγράφονται υπερβάσεις των προβλεπόμενων οριακών τιμών για την προστασία της υγείας. Παρόλα αυτά, οι μελέτες στα αστικά κέντρα της περιοχής για Πτητικούς Οργανικούς Υδρογονάνθρακες (Volatile Organic Compounds ή VOC), οι οποίοι είναι πρόδρομοι του τροποσφαιρικού όζοντος (Ο3) και των αερολυμάτων, είναι περιορισμένες, ενώ ορισμένες υποδεικνύουν αβεβαιότητες στις παρατηρήσεις που προκύπτουν από συγκρίσεις με βάσεις δεδομένων εκπομπών, σχετιζόμενες με τη συνεισφορά των πηγών εκπομπής και το χημικό τους αποτύπωμα. Συνεπώς, η Αθήνα αποτελεί ιδανική τοποθεσία για μετρήσεις των ενώσεων αυτών, λόγω της μη-καταγραφής των επιπέδων τους τα τελευταία 15 χρόνια (πλην ελάχιστων εξαιρέσεων), της συνεχούς υπέρβασης των ορίων του Ο3 και των αερολυμάτων, καθώς και της αύξησης των εκπομπών από μέχρι πρότινος ασθενείς πηγές ρύπων (π.χ. καύση ξύλου για οικιακή θέρμανση). Στην παρούσα εργασία παρουσιάζονται τα αποτελέσματα μιας 17μηνης καμπάνιας ατμοσφαιρικών μετρήσεων πεδίου για μη-Μεθανικούς Υδρογονάνθρακες (non-Methane Hydrocarbons ή NMHCs) στην Αθήνα (Οκτώβριος 2015 - Φεβρουάριος 2017), στο πλαίσιο του διεθνούς προγράμματος ChArMEX (The Chemistry - Aerosol Mediterranean Experiment). Παράλληλα, εκπονήθηκαν δύο εντατικές περίοδοι εποχικών μετρήσεων (χειμώνα και καλοκαίρι) στον ίδιο σταθμό και επιπλέον, δύο εκστρατείες συλλογής δειγμάτων αέρα σε γνωστές πηγές ρύπανσης (σήραγγα και αστικός σταθμός μετρήσεων).Τα δεδομένα περισσότερων από 40 VOC με 2 έως 16 άτομα άνθρακα, που συλλέχθηκαν κατά τη διάρκεια της καμπάνιας, χρησιμοποιήθηκαν για τη μελέτη της ημερήσιας και εποχιακής διακύμανσης τους σε ετήσια βάση και των παραγόντων που την επηρεάζουν, ενώ τα επίπεδα C2 - C3 NMHCs στην Αθήνα παρουσιάζονται για πρώτη φορά. Η εποχικότητα παρουσιάζει σαφή διακύμανση, με μέγιστο το χειμώνα και ελάχιστο το καλοκαίρι για την πλειονότητα των ενώσεων, ενώ η ημερήσια διακύμανση επηρεάζεται από την ένταση των εκπομπών των πηγών, την ταχύτητα του ανέμου και το ύψος του στρώματος ανάμειξης. Η σύγκριση των αποτελεσμάτων αυτών με παρόμοιες έρευνες σε άλλες πόλεις ανέδειξαν το ρόλο των πηγών στα παρατηρούμενα επίπεδα, όπου για την Αθήνα αυτή η επίδραση είναι πιο έντονη τον χειμώνα. Επιπρόσθετα, τα μονοτερπένια και το ισοπρένιο, γνωστές ενώσεις βιογενούς προέλευσης, παρουσίασαν μία μοναδική μεταβλητότητα επηρεασμένη από ανθρωπογενείς εκπομπές, η οποία δεν λαμβάνεται υπόψη κατά την εκτίμηση της ποιότητας του αέρα. Τέλος, η χρήση του στατιστικού μοντέλου Positive Matrix Factorization (PMF) επέτρεψε τον προσδιορισμό των κύριων πηγών NMHCs στην Αθήνα και την εκτίμηση της συνεισφοράς τους στα επίπεδα των συγκεντρώσεων. Από αυτές, οι εκπομπές από την κίνηση οχημάτων και την οικιακή θέρμανση επικρατούν, ενώ μια δεύτερη PMF προσομοίωση στα δεδομένα της εποχικής εντατικής περιόδου παρατήρησης επιβεβαίωσε τα αποτελέσματα, δίνοντας επίσης πληροφορίες για πρόσθετες πηγές.

scholarly journals Volatile organic compounds over Eastern Himalaya, India: temporal variation and source characterization using Positive Matrix Factorization

2014 ◽  
Vol 14 (23) ◽  
pp. 32133-32175 ◽  
Author(s):  
C. Sarkar ◽  
A. Chatterjee ◽  
D. Majumdar ◽  
S. K. Ghosh ◽  
A. Srivastava ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Solar Radiation ◽  
Organic Compounds ◽  
Matrix Factorization ◽  
Anthropogenic Activities ◽  
Positive Matrix Factorization ◽  
Eastern Himalaya ◽  
Source Characterization ◽  
Positive Matrix ◽  
Volatile Organic

Abstract. A first ever study on the characterization of volatile organic compounds (VOCs) has been made over a Himalayan high altitude station in India. A total of 18 VOCs (mono aromatics-BTEX (benzene, toluene, ethylbenzene, xylene), non-BTEX substituted aromatics and halocarbon) have been measured over Darjeeling (27.01° N, 88.15° E, 2200 m a.s.l.) in the eastern Himalaya in India during the period of July 2011–June 2012. The annual average concentration of the sum of 18 target VOCs (TVOC) was 376.3 ± 857.2 μg m−3. Monoaromatics had the highest contribution (72%) followed by other substituted aromatics (22%) and halocarbon (6%) compounds. Toluene was the most abundant VOC in the atmosphere of Darjeeling with the contribution of ~37% to TVOC followed by benzene (~21%), ethylbenzene (~9%) and xylenes (~6%). TVOC concentrations were highest during the postmonsoon season with minimum solar radiation and lowest during the premonsoon season with maximum solar radiation. Anthropogenic activities related mainly to tourists like diesel and gasoline emissions, biomass and coal burning, use of solvent and solid waste emissions were almost equal in both the seasons. Seasonal variation in TVOCs over Darjeeling was mainly governed by the incoming solar radiation rather than the emission sources. Source apportionment study using Positive Matrix Factorization (PMF) model indicated that major fraction of (~60%) TVOC were contributed by diesel and gasoline exhausts followed by solvent evaporation (18%) and other sources. Diesel exhaust was also found to have the maximum potential in tropospheric ozone formation. The atmospheric loading of BTEX over Darjeeling was found to be comparable with several Indian metro cities and much higher than other cities around the world.

scholarly journals Sources of Selected Chemical Components in Atmospheric Components in Finland

2021 ◽  
Author(s):  
◽  
Mika Vestenius
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Air Quality ◽  
Boreal Forest ◽  
Organic Compounds ◽  
Matrix Factorization ◽  
The Arctic ◽  
Positive Matrix ◽  
Natural Sources ◽  
Helsinki Metropolitan Area

Air pollution is an important environmental risk to human health and ecosystems around the world. Particulate matter (PM), especially fine particulate matter, is an important part of this air pollution problem. Particle composition varies greatly and depends on the emission source. In addition to inorganic components, organic particulate fraction can contain several hundred organic compounds from anthropogenic and natural sources. The health risk of particulate is related to the particle size and the compounds inside or on the surface of the aerosol particles. The overall aim of this thesis was to study the selected chemical substances of atmospheric aerosol from both anthropogenic and natural sources. Concentrations of polycyclic aromatic hydrocarbons (PAH) and biogenic organic acids in aerosol were measured, and their effect on the local air quality was estimated. The sources of PAHs, trace elements, biogenic volatile organic compounds (BVOCs), and persistent organic compounds (POPs) in air were studied using positive matrix factorization (PMF), which was used as the main source apportionment tool in three of five papers and for the unpublished data in this thesis. Particles from burning emissions, e.g., diesel particles and particles from biomass burning, are the most toxic in our daily environment. Because of intensive wood use for heating and in sauna stoves, residential biomass burning is the major PAH air pollution source in Finland. Sources of atmospheric PAH pollution and its influence on local air quality were estimated at Virolahti background air quality station and in the Helsinki Metropolitan Area (HMA). The main source of PAHs at Virolahti were found to be combustion- and traffic-related source from the direction of St. Petersburg. Instead, local traffic appeared to have a very small influence on PAH levels in HMA, as local residential wood burning was found to be the main b(a)p source in Helsinki Metropolitan Area. Biogenic VOCs like monoterpenes and sesquiterpenes are highly reactive and oxidize rapidly in the atmosphere, producing secondary organic aerosol (SOA). We showed that positive matrix factorization (PMF) is a useful tool in estimating separate sources in a quasistationary dynamic system like ambient VOC concentrations in the boreal forest. Selected biogenic organic acids were measured from fine particles in the boreal forest in order to estimate their influence on aerosol production. Results indicated that sesquiterpene emissions from boreal forest are probably underestimated and their oxidation products probably have more important role in the SOA production that previously estimated. The Kola Peninsula area was found to be the major source of heavy metal pollution at Pallas. However, as Norilsk Nickel has now partly shut down its metallurgical operations, the trace element and SO2 emissions from the Kola Peninsula should be declining in the future. The ambient concentrations of POP compounds are globally declining but, in the Arctic, for some compounds this is not the case. In the source apportionment study for Pallas 1996–2018 POPs data, relatively big portion of measured POPs at Pallas came within the marine source from clean areas from the north. These long-lived compounds, which have migrated into the Arctic from the southern areas along the air and sea currents for many decades, are now released back into the atmosphere from the melting Arctic ice cover due to global warming. For these compounds, the Arctic has turned from the sink to the source.

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