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Abstract The real-time continuous measurements of non-refractory submicron aerosol (NR-PM 1) species including organics (Org), sulfate (SO 4 2−), nitrate (NO 3 −), ammonium (NH 4 +) and chloride (Cl−) in winter from 10 December 2015 to 30 January 2016 in Beijing were performed with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM). The average concentration of NR-PM 1 was 81.24 μg m−3, with the mean concentration in heavy haze days being 220.00 μg m−3, ∼3 times higher than that in light haze days and ∼15 times higher than that in clean days. Org was the most significant component of NR-PM 1 species, accounting for 53% of the total NR-PM 1 for the entire study. SO 4 2− was also a significant component, accounting for 23% of the total NR-PM 1. However, NO 3 −, NH 4 + and Cl− composition together accounted for 25% of the total NR-PM 1. All NR-PM 1 species presented remarkably diurnal cycles in haze days, characterized by the highest concentrations occurring at midnight, and the lowest concentrations occurring at daytime. Note that the sulfur oxidation ratios were higher than the nitrogen oxidation ratios for the entire study, especially during the haze periods. The formation of sulfate was mainly affected by relative humidity (RH), while that of nitrate was more associated with NH 3. Heterogeneous oxidation of NO 2 on the surfaces of aerosol particles might be a significant pathway of nitrate formations during haze periods. NR-PM 1 was mainly from secondary chemical reactions contributing 46.1%, vehicle emissions contributing 22.3%, coal combustion contributing 16.1%, and biomass burning contributing 15.6% in clean days. However, compared to the clean-day source contributions, the haze-day secondary source contribution to NR-PM 1 increased to 66.8%, indicating that NR-PM 1 in haze days was dramatically dominated by the secondary pollutants. Highlights • The formation of sulfate was mainly affected by relative humidity (RH), while that of nitrate was more associated with NH 3. • Heterogeneous oxidation of SO 2 might be a significant pathway of sulfate formations during haze periods. • Heterogeneous oxidation of NO 2 might be a significant pathway of nitrate formations during haze periods. • NR-PM 1 in haze days was dramatically dominated by the secondary pollutants. [ABSTRACT FROM AUTHOR]

Equivalent black carbon ( E B C ) mass concentrations in the fine inhalable fraction of airborne particles ( P M 2.5 ) were determined using a 7-wavelength Aethalometer for 17 months, between November 2014 and March 2016, for a suburban location of the Metropolitan Area of Buenos Aires (MABA), Argentina. In addition to describing seasonal and diurnal black carbon (BC) cycles for the first time in this region, the relative contributions of fossil fuel and remote and local biomass burning were determined by distinguishing different carbonaceous components based on their effect on light attenuation for different wavelengths. Trajectory analyses and satellite-based fire products were used to illustrate the impact of long-range transport of particles emitted by non-local sources. EBC data showed a marked diurnal cycle, largely modulated by traffic variations and the height of the boundary layer, and a seasonal cycle with monthly median EBC concentrations (in μ g / m 3 ) ranging from 1.5 (February) to 3.4 (June). Maximum values were found during winter due to the combination of prevailingly stable atmospheric conditions and the increase of fossil fuel emissions, derived primarily from traffic and biomass burning from the domestic use of wood for heating. The use of charcoal grills was also detected and concentrated during weekends. The average contribution of fossil fuel combustion sources to E B C concentrations was 96%, with the remaining 4% corresponding to local and regional biomass burning. During the entire study period, only two events were identified during which E B C concentrations attributed to regional biomass burning accounted for over 50% of total E B C ; these events demonstrate the relevance of agricultural and forestry activities that take place far from the city yet whose emissions can affect the urban atmosphere of the MABA. [ABSTRACT FROM AUTHOR]

This study aims to determine the seasonal variations and composition of suspended particulate matter in different sizes PM 1.0 , PM 2.5 , PM 10 and the total suspended particles (TSP) emitted at major intra-urban traffic intersections (TIs) of Ilorin metropolis. The concentration levels of PM (PM 1.0 , PM 2.5 , PM 10 ) obtained at the TIs during the rush hours (45.1, 77.9, and 513 μg/m 3 ) are higher than the levels obtained for the non-rush hour periods (42.3, 62.7, and 390 μg/m 3 ). The average on-road respiratory deposition dose (RDD) rates of PM 1.0 , PM 2.5 and PM 10 during the dry period at TIs types was found to be about 24%, 9% and 25% higher than those obtained during the wet period. Based on EF values calculated, Pb and Zn were anthropogenically-derived while Fe, Mn, Cr, Cu and Mg were of crustal source. Principal component analysis (PCA) has been applied to a set of PM data in order to determine the contribution of different sources. It was found that the main principal factors extracted from particulate emission data were related to exhaust and non-exhaust emissions such as tyre wears, oil and fuel combustion sources. [ABSTRACT FROM AUTHOR]

This paper describes the use of a unique valve switching system that allowed for high temporal resolution indoor and outdoor data to be collected concurrently from online C-ToF-AMS, SMPS and OC/EC, and offline BLPI measurements. The results reveal near real-time dynamic aerosol behaviour along a migration path from an outdoor to indoor environment. An outdoor reduction in NR-PM 1 mass concentration occurred daily from AM (06:00–12:00) to PM (12:00–18:00). SO 4 (26%–37%) [AM/PM] increased proportionally during afternoons at the expense of NO 3 (18%–7%). The influences of mixing height, temperature and solar radiation were considered against the mean mass concentration loss for each species. Losses were then calculated according to species via a basic input/output model. NO 3 lost the most mass during afternoon periods, which we attribute to the accelerated dissociation of NH 4 NO 3 through increasing temperature and decreasing relative humidity. Indoor/outdoor (I/O) ratios varied from 0.46 for <40 nm to 0.65 for >100 nm. These ratios were calculated using average SMPS PNC measurements over the full campaign and corroborated using a novel technique of calculating I/O penetration ratios through the indoor migration of particles during a new particle formation event. This ratio was then used to observe changes in indoor composition relative to those outdoors. Indoor sampling was carried out in an undisturbed room with no known sources. Indoor concentrations were found to be proportional to those outdoors, with organic matter [2.7 μg/m 3 ] and SO 4 [1.7 μg/m 3 ] being the most prominent species. These results are indicative of fairly rapid aerosol penetration, a source-free indoor environment and small afternoon I/O temperature gradients. Fine fraction NO 3 was observed indoors in both real-time AMS PM 1 and off-line BLPI measurements. Greater mass concentration losses were observed from filter measurements, highlighting an important time dependency factor when investigating semi-volatiles. Coarse mode NO 3 was observed by impactor measurements, ascribing value to observing the full particle mass size distribution for understanding aerosol origin. [ABSTRACT FROM AUTHOR]

A novel in-situ, real time method for the determination of inherent absorption properties of light absorbing carbonaceous particulate matter and its possible application for source apportionment are introduced here. The method is deduced from a two-week campaign under wintry urban conditions during which strong correlation was found between aerosol number size distribution and wavelength dependent optical absorption coefficient ( AOC(λ) ), measured by a Single Mobility Particle Sizer (SMPS) and a multi-wavelength photoacoustic absorption spectrometer, respectively, while wood burning and traffic (i.e. fossil fuel burning) activity were identified to be the dominant sources of carbonaceous particulate. Indeed, during the whole campaign, regardless of the actual emission strength of the aerosol sources, the measured number size distributions were always dominated by two unimodal modes with Count Mean Diameter (CMD) of 20 and 100 nm, which could be correlated to traffic and wood burning activities, respectively. AAE ff , AAE wb (i.e. the Aerosol Angström Exponent of traffic and wood burning aerosol, respectively), σ ff (266 nm) , σ ff (1064 nm) , σ wb (266 nm) and σ ff (1064 nm) (i.e. the segregated mass specific optical absorption coefficients at two of the measurement wavelengths) were found to be 1.17 ± 0.18, 2.6 ± 0.14, 7.3 ± 0.3 m 2 g −1 , 1.7 ± 0.1 m 2 g −1 3.4 ± 0.3 m 2 g −1 and 0.31 ± 0.08 m 2 g −1 , respectively. Furthermore the introduced methodology can also disentangle and quantify the temporal variation of both the segregated optical absorptions and the segregated mass concentrations of traffic and wood burning aerosol. Accordingly, the contribution of wood burning to optical absorption of PM was found to be negligible at 1064 nm but increased gradually towards the shorter wavelengths and became commensurable with the optical absorption of traffic at 266 nm during the whole measurement period. Furthermore, the contribution of wood burning mass to CM (mass of carbonaceous particulate matter) was dominant regardless of the strength of the emission activity of traffic and wood burning during the whole measurement period. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare co-located real-time light scattering devices and equivalent gravimetric samplers in poultry and pig houses for PM 10 mass concentration, and to develop animal-specific calibration factors for light scattering samplers. These results will contribute to evaluate the comparability of different sampling instruments for PM 10 concentrations. Paired DustTrak light scattering device (DustTrak aerosol monitor, TSI, U.S.) and PM 10 gravimetric cyclone sampler were used for measuring PM 10 mass concentrations during 24 h periods (from noon to noon) inside animal houses. Sampling was conducted in 32 animal houses in the Netherlands, including broilers, broiler breeders, layers in floor and in aviary system, turkeys, piglets, growing-finishing pigs in traditional and low emission housing with dry and liquid feed, and sows in individual and group housing. A total of 119 pairs of 24 h measurements (55 for poultry and 64 for pigs) were recorded and analyzed using linear regression analysis. Deviations between samplers were calculated and discussed. In poultry, cyclone sampler and DustTrak data fitted well to a linear regression, with a regression coefficient equal to 0.41, an intercept of 0.16 mg m −3 and a correlation coefficient of 0.91 (excluding turkeys). Results in turkeys showed a regression coefficient equal to 1.1 (P = 0.49), an intercept of 0.06 mg m − 3 (P < 0.0001) and a correlation coefficient of 0.98. In pigs, we found a regression coefficient equal to 0.61, an intercept of 0.05 mg m −3 and a correlation coefficient of 0.84. Measured PM 10 concentrations using DustTraks were clearly underestimated (approx. by a factor 2) in both poultry and pig housing systems compared with cyclone pre-separators. Absolute, relative, and random deviations increased with concentration. DustTrak light scattering devices should be self-calibrated to investigate PM 10 mass concentrations accurately in animal houses. We recommend linear regression equations as animal-specific calibration factors for DustTraks instead of manufacturer calibration factors, especially in heavily dusty environments such as animal houses. [ABSTRACT FROM AUTHOR]