To comply with environmental regulations, ship operators may adopt exhaust after-treatment devices such as scrubbers or selective catalytic reduction (SCR). Beyond gaseous emission control, these technologies impact the exhaust particles emitted from marine engines to the atmosphere. This study characterizes comprehensively the chemical composition and physical properties of exhaust aerosol particles upstream and downstream a hybrid scrubber operating in open loop mode on-board a modern cruise ship. The study considers two engines, one equipped with SCR and both with scrubber, during engine load conditions of 75 % and 40 %, and the influence of marine gas oil (MGO) use in addition to heavy fuel oil (HFO). At least 4 different particle types were observed in the exhaust based on transmission electron microscopy (TEM) studies both upstream and downstream scrubber, and both scrubber and SCR affected the particle number size distribution (PSD). The geometric mean diameter (GMD) of the particles increased over scrubber both due to removal of nucleation mode particles and particle growth in the scrubber. The scrubber effectively decreased particle number (PN) and, also, non-volatile particles, but the effect depended on particle size and no significant decrease was observed in number of particles above 50 nm, typically comprising black carbon (BC) and in the case of HFO combustion, also asymmetrical metal containing particles. In addition to PN, concentrations of PAH compounds were reduced in the scrubber. The results may be further utilized when including the exhaust aerosol characteristics from ships applying scrubbers to emission inventories, as well as climate and air quality models.

It has become evident that additional metrics along the particle mass concentration, together with dense air quality monitoring networks within cities, are needed to understand the most efficient ways to tackle the health burden of particulate pollution. Particle lung-deposited surface area (LDSAal) is a metric to estimate particle exposure in the lung alveoli, and it has gained interest as a parameter for air quality monitoring as it is relatively easy and cost-efficient to measure with electrical particle sensors. Also, various studies have indicated its potential as a health-relevant metric. In addition to the electrical particle sensors, the LDSAal can be measured with various size distribution methods. However, different LDSAal measurement methods have fundamental differences in their operation principles, e.g., related to the measurement size ranges, size classification or conversion from the originally measured quantity into the LDSAal. It is not well understood how these differences affect the accuracy of the measurement in ambient conditions, where especially the particle effective density and hygroscopicity can considerably change the particle lung deposition efficiencies. In this study, the electrical particle sensor measurement (Partector) and two size distribution approaches (ELPI+ and DMPS/SMPS) were compared in road traffic environments with different environmental conditions in Helsinki and Prague. The results were compared by utilising the general assumptions of the LDSAal measurement (spherical hydrophobic particles with the standard density) and by evaluating the effects of the particle effective density and hygroscopicity. Additionally, the Partector and ELPI+ approaches were compared in various urban environments near road traffic, airports, river traffic and residential wood combustion. The results show that the comparison of different LDSAal measurement methods can be complicated in ambient measurements. The challenges were especially related to the accumulation mode particles roughly larger than 200–400 nm for which the dominant deposition mechanism in the lung changes from diffusion to impaction and the particle effective density and hygroscopicity tend to increase. On the other hand, the results suggest that the differences between the methods are reasonably low when considering only ultrafine and soot particles, which have an effective density closer to the standard (1.0 g cm−3) and are more hydrophobic, highlighting the suitability of the LDSAal as a monitored metric when estimating the spatial differences in the particulate pollution within cities.

European policy efforts to address air quality issues have led to significant reductions in pollutants over time. Despite this progress, the decrease is not homogeneous across all pollutants, as certain pollutants still exceed the thresholds set for air quality and health standards. The RI-URBANS project takes advantage of the expertise of the research infrastructures to carry out a coordinated experiment using state-of-the-art technologies in 13 European cities, where chemical composition has been studied throughout 2023. Its goal is to enhance the understanding and management of urban air quality providing a near real-time visualization and source apportionment online tool. This paper focuses on chemical characterization and source apportionment of organic aerosols, presenting data from the measurement campaign in Milan as part of the project. Innovative measurements of non- refractory aerosols using the ToF-ACSM mass spectrometer, along with black carbon concentration measurements derived from optical techniques (AE33, 7 lambda), lambda ), enabled continuous monitoring of various emission sources with high temporal resolution. The coordinated analysis involved Positive Matrix Factorization (PMF) and the bilinear model for black carbon source attribution application in each city, which were then compared with the project's new tool. Results provide insight into aerosol concentrations in the urban background of Milan throughout 2023, and an initial estimation of organic aerosol sources, highlighting significant seasonal variations. Detailed analysis will be deferred in forthcoming publications.

Particulate matter (PM) is emitted from various anthropogenic sources in urban areas affecting the local air quality. The aim of this study was to characterize the sources influencing air quality in detached house area in the Helsinki metropolitan area in Finland, and secondly, to explore the additional value of new particle physical properties to assess the impact of residential combustion on air quality. Measurements were conducted in an urban detached housing area between January and April 2019. Measured particle physical properties were particle number (PN), particle mass (PM1) and lung deposited surface area (LDSA) concentrations and number size distributions. In addition, particle chemical composition was measured using a soot particle aerosol mass spectrometer (SP-AMS; organic compounds, inorganic ions) and an aethalometer (black carbon (BC)). Concentrations of selected monosaccharide anhydrides and polycyclic aromatic hydrocarbons were analysed from the PM10 filter samples. The sources and characteristics of organic aerosol was investigated by applying positive matrix factorization to the mass spectra measured with the SP-AMS. Based on the variations in the measured particle physical parameters, chemical species and meteorology, the measurement period was divided into three sub periods dominated by urban background, wood burning and long-range transport (LRT) aerosols. Highest pollutant concentrations were measured during the wood burning and LRT periods. Wood burning increased the concentrations of all measured species, but the differences were most significant to levoglucosan, benzo(a)pyrene, BC and PM1 that had 12, 10, 6.4 and 3.6 times larger mean concentrations during the wood burning period compared to the urban background period, respectively. LRT affected significantly levoglucosan, PM1 and BC concentrations, since LRT pollutants partly originated from open biomass fires in Eastern Europe. The impact of local wood burning and LRT was quite small to particle number concentrations, whereas LDSA concentrations and size distributions were affected by traffic, wood combustion emissions and LRT. BC concentration correlated with the LDSA concentration during all periods suggesting a common origin. Particle number concentration was a good indicator of local combustion, especially traffic emissions, while the PM1 mass concentration together with secondary particle material was a good measure for the LRT pollutants. Benzo(a)pyrene was found to be a good indicator of local wood burning, but it was not detected in LRT biomass combustion particles.

The absorption Ångström exponent (AAE) describes the spectral dependence of light absorption by aerosols. AAE is typically used to differentiate between different aerosol types for example., black carbon, brown carbon, and dust particles. In this study, the variation of AAE was investigated mainly in fresh aerosol emissions from different fuel and combustion types, including emissions from ships, buses, coal‐fired power plants, and residential wood burning. The results were assembled to provide a compendium of AAE values from different emission sources. A dual‐spot aethalometer (AE33) was used in all measurements to obtain the light absorption coefficients at seven wavelengths (370–950 nm). AAE470/950 varied greatly between the different emission sources, ranging from −0.2 ± 0.7 to 3.0 ± 0.8. The correlation between the AAE470/950 and AAE370‐950 results was good (R2 = 0.95) and the mean bias error between these was 0.02. In the ship engine exhaust emissions, the highest AAE470/950 values (up to 2.0 ± 0.1) were observed when high sulfur content heavy fuel oil was used, whereas low sulfur content fuels had the lowest AAE470/950 (0.9–1.1). In the diesel bus exhaust emissions, AAE470/950 increased in the order of acceleration (0.8 ± 0.1), deceleration (1.1 ± 0.1), and steady driving (1.2 ± 0.1). In the coal‐fired power plant emissions, the variation of AAE470/950 was substantial (from −0.1 ± 2.1 to 0.9 ± 1.6) due to the differences in the fuels and flue gas cleaning conditions. Fresh wood‐burning derived aerosols had AAE470/950 from 1.1 ± 0.1 (modern masonry heater) to 1.4 ± 0.1 (pellet boiler), lower than typically associated with wood burning, while the burn cycle phase affected AAE variation.

In households, municipal solid waste (MSW) is often burned along with wood to get rid of waste, to help in ignition or simply to reduce fuel costs. The aim of this study was to characterize the influence of household waste combustion, along with wood, on the physical and chemical properties of particulate emissions in a flue gas of a masonry heater. The MSW burning alongside wood increased average particulate matter (PM) mass (65%), lung deposited surface areas (LDSA, 15%), black carbon (BC, 65%) concentrations and the average particle size in the flue gas. The influence of MSW was smaller during ignition and burning phases, but especially during fuel additions, the mass, number, and LDSA concentrations increased significantly and their size distributions moved towards larger particles. For wood burning the trace metal emissions were relatively low, but significant increase (3.3-179 -fold increase over cycle) was seen when MSW was burned along the wood. High ratios were observed especially during fuel addition phases but, depending on compounds, also during ignition and burning end phases. The highest ratios were observed for chloride compounds (HCl, KCl, NaCl). The observed increase in light-absorbing particle, trace metal and BC concentrations in flue gas when adding wood with MSW are likely to have negative impacts on air quality, visibility, human health and climate. Furthermore, metals may also affect the condition and lifetime of the burning device due to corrosion.

Exhaust emissions from Euro 2-6a cars using diesel, gasoline, high concentration ethanol (E85) fuel and compressed natural gas (CNG) were studied comprehensively, with a focus on results obtained at -7 degrees C test temperature. Higher emissions than desired were noticed in some cases, e.g. elevated methane emissions from natural gas fuelled cars, as well as methane and acetaldehyde emissions from E85 fuelled flexible fuel vehicles. Additionally, mutagenicity of PM samples and oxidative potential of semivolatile samples were observed. However, emission performance improved significantly when moving from older to newer Euro 6a cars, showing that low tailpipe exhaust emissions can be achieved when combining new car technology with CNG, E85, gasoline and diesel fuels. Furthermore, the climate impact of these technologies could reduce by using renewable counterparts of these fuels.

Chemical characteristics and the sources of submicron particles (< 1 μm in diameter) were investigated in Valle Alegre, the coastal area of Central Chile. The chemical composition of particles was studied by using a Soot particle Aerosol Mass Spectrometer and Multi-Angle Absorption Photometer. Submicron particles were dominated by organics (42% of mass) and sulfate (39% of mass) while the mass fractions of ammonium, nitrate and black carbon were much smaller (13, 2 and 4% of mass, respectively). Additionally, several metals (V, Zn, Fe, Cd, Cu, K, Na and Mg) were detected in submicron particles and also some of their inorganic salts (e.g. NaCl, MgCl2, CaCl2, KCl and KNO3). The sources of particles were examined by using Positive Matrix Factorization (PMF). Organic aerosol (OA) was divided into five factors by using PMF; hydrocarbon-like OA (HOA), biomass burning OA (BBOA), low-volatility oxygenated OA (LV-OOA), semi-volatile OA (SV-OOA) and marine oxygenated OOA (MOOA). Oxygenated factors (LV-OOA; SV-OOA and MOOA) comprised 75% of total OA with LV-OOA being the dominant factor (38% of OA). Sulfate had two major sources in Valle Alegre; ∼70% of sulfate was related to anthropogenic sources through the oxidation of gas phase SO2 whereas ∼24% of sulfate was associated with biogenic origin related to the oxidation of dimethyl sulfide in the marine environment. Regarding total submicron particle mass (campaign-average 9.5 μgm), the contribution of anthropogenic sources was at least as large as that of biogenic origin.

Particulate matter (PM) from mining operations, engines, and ore processing may have adverse effects on health and well-being of workers and population living nearby. In this study, the characteristics of PM in an underground chrome mine were investigated in Kemi, Northern Finland. The concentrations and chemical composition of PM in size ranges from 2.5 nm to 10 mu m were explored in order to identify sources, formation mechanisms, and post-emission processes of particles in the mine air. This was done by using several online instruments with high time-resolution and offline particulate sampling followed by elemental and ionic analyses. A majority of sub-micrometer particles (< 1 mu m in diameter, PM1) originated from diesel engine emissions that were responsible for a rather stable composition of PM1 in the mine air. Another sub-micrometer particle type originated from the combustion products of explosives (e.g., nitrate and ammonium). On average, PM1 in the mine was composed of 62%, 30%, and 8% of organic matter, black carbon, and major inorganic species, respectively. Regarding the analyzed elements (e.g., Al, Si, Fe, Ca), many of them peaked at > 1 mu m indicating mineral dust origin. The average particle number concentration in the mine was (2.3 +/- 1.4)*10(4) #/cm(3). The maximum of particle number size distribution was between 30 and 200 nm for most of the time but there was frequently a distinct mode < 30 nm. The potential origin of nano-size particles remained as challenge for future studies.

Particle emission characteristics for a medium-speed four-stroke marine diesel engine were studied using a variety of sampling systems. Measurements were conducted at 25% and 75% load employing a heavy fuel oil (HFO) and a lighter marine distillate oil. The measurements, especially with HFO, revealed that marine exhaust particles mostly consist of nanometer sized ash particles on which heavy volatile species condense during exhaust dilution and cooling. The soot mode number concentration was low with both fuels tested, in particular when HFO was used. Total particle number emissions ranged in the order of 5.2-6.9 x 10(15) per kg of fuel and formed a monomodal size distribution when a porous tube diluter combined with an ageing chamber and operating at low dilution ratio was used for sampling. The levels and size distributions obtained in the lab using a porous tube diluter were similar to the ones reported in the literature studying ship plumes following atmospheric dilution. Lab measurements with ejector-type diluters mostly led to bimodal distributions that did not well resemble atmospheric size distributions. Moreover, the nucleation mode formed with the ejector diluters was variable in size and concentration. When used with dilution air at ambient temperature, ejector diluters were inappropriate for primary dilution due to clogging. (C) 2016 Elsevier Ltd. All rights reserved.

Detailed chemical characterization of exhaust particles from 23 individual city buses was performed in Helsinki, Finland. Investigated buses represented different technologies in terms of engines, exhaust after-treatment systems (e.g., diesel particulate filter, selective catalytic reduction, and three-way catalyst) and fuels (diesel, diesel-electric (hybrid), ethanol, and compressed natural gas). Regarding emission standards, the buses operated at EURO III, EURO IV, and EEV (enhanced environmentally friendly vehicle) emission levels. The chemical composition of exhaust particles was determined by using a soot particle aerosol mass spectrometer (SP-AMS). Based on the SP-AMS results, the bus emission particles were dominated by organics and refractory black carbon (rBC). The mass spectra of organics consisted mostly of hydrocarbon fragments (54-86% of total organics), the pattern of hydrocarbon fragments being rather similar regardless of the bus type. Regarding oxygenated organic fragments, ethanol-fueled buses had unique mass-to-charge ratios (m/z) of 45, 73, 87, and 89 (mass fragments of C2H5OC, C3H5O2+, C4H7O2+, and C4H9O2+, respectively) that were not detected for the other bus types at the same level. For rBC, there was a small difference in the ratio of C-4(+) and C-5(+) to C-3(+) for different bus types but also for the individual buses of the same type. In addition to organics and rBC, the presence of trace metals in the bus emission particles was investigated.

A method to detect and quantify mass concentrations of trace metals on soot particles by the Aerodyne soot-particle aerosol mass spectrometer (SP-AMS) was developed and evaluated in this study. The generation of monodisperse Regal black (RB) test particles with trace amounts of 13 different metals (Na, Al, Ca, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr and Ba) allowed for the determination of the relative ionization efficiency of each metal relative to black carbon (RIEmeas). The observed RIEmeas/RIEtheory values were larger than unity for Na, Rb, Ca, Sr and Ba due to thermal surface ionization (TSI) on the surface of the laser-heated RB particles. Values closer to unity were obtained for the transition metals Zn, Cu, V and Cr. Mn, Fe, and Ni presented the lowest RIEmeas/RIEtheory ratios and highest deviation from unity. The latter discrepancy is unexplained; however it may be related to problems with our calibration method and/or the formation of metal complexes that were not successfully quantified. The response of the metals to the laser power was investigated and the results indicated that a minimum pump laser current of 0.6 A was needed in order to vaporize the metals and the refractory black carbon (rBC). Isotopic patterns of metals were resolved from high-resolution mass spectra, and the mass-weighted size distributions for each individual metal ion were obtained using the high-resolution particle time-of-flight (HR-PToF) method. The RIEmeas values obtained in this study were applied to the data of emission measurements in a heavy-fuel-oil-fired heating station. Emission measurements revealed a large number of trace metals, including evidence for metal oxides and metallic salts, such as vanadium sulfate, calcium sulfate, iron sulfate and barium sulfate, which were identified in the SP-AMS high-resolution mass spectra. SP-AMS measurements of Ba, Fe, and V agreed with ICP-MS analyzed filter samples within a factor of 2 when emitted rBC mass loadings were elevated.

University of Washington (Graduate Program in Astrobiology); National Science Foundation IGERT; National Geographic Society Waitt Grants Program; NASA Astrobiology Institute Director’s Discretionary Fund; Washington NASA Space Grant Consortium; University of Washington Biology Department (Sargent Award); NASA Kennedy Space Center; NASA Ames Research Center; NASA Space Biology Pogram; The Mt. Bachelor Ski Resort; Kevin Perry, Bryan Hicks, Patrick Ball, Carol Higginbotham, Tom Lomax, Victoria Long, Clara Wright, Phil Howard, John Catechis, Gerard Newsham, and Martin Hayes. REFERENCES Globally-dispersed airborne microorganisms are poorly understood. However, in spring 2011 at the Mt. Bachelor Observatory in North America (2.8 km above sea level), we captured sufficient microbial biomass in two transpacific air masses to permit a 16S ribosomal RNA microarray analysis. In each episode, we detected 2,800+ distinct microbial taxa. Transport across the Pacific Ocean from Asia was independently measured through meteorological/chemical data and microbial biogeography. Our results indicate that upper atmosphere winds can bridge microbial populations between distant continents. The presence, persistence and detectability of life in planetary atmospheres broadens the definition of habitable environments in the solar system (and beyond). ABSTRACT

In this study concentrations of organic (OC) and elemental carbon (EC) from free tropospheric (FT) fine particulate matter (PM) were measured from March to September, 2012 with a Semi-Continuous OC/EC carbon aerosol analyzer at the top of Mt. Bachelor (2.8 km a.s.l) in Central Oregon, U.S. The average concentrations of OC and EC in the FT were low (OC: 1.87 +/- 6.10, EC: 0.07 +/- 0.26 mu g m(-3); average +/- SD) but much higher during specific pollution episodes. During springtime the highest OC and EC concentrations were measured for dry free tropospheric air masses, whereas during summertime the highest OC and EC concentrations were typically measured for more humid air masses that were uplifted from the boundary layer (BL). The highest OC and EC concentrations were measured during biomass burning episodes (3 h average OC: up to 146.0 mu g m(-3), EC up to 5.5 mu g m(-3)). Elevated OC and EC concentrations were also measured during Asian Long Range Transport (LRT) episodes (OC: up to 3.6 mu g m(-3), EC up to 1.1 mu g m(-3)). In addition, between episodes, an increase in OC was seen in the afternoon, possibly due to SOA formation. This SOA can then be exported to the FT via diurnal ventilation of the BE For Asian LRT episodes the OC/EC ratios varied between 8 and 34, with an average of 17.9. For local biomass burning emissions OC/EC ratios were between 25 and 30. Higher OC/EC ratios (30-40) were observed for the biomass burning plumes originating from longer distances, possibly due to SOA formation. (C) 2014 Elsevier Ltd. All rights reserved.

Mercury (Hg) is a neurotoxin that bioaccumulates in the food chain. Mercury is emitted to the atmosphere primarily in its elemental form, which has a long lifetime allowing global transport. It is known that atmospheric oxidation of gaseous elemental mercury (GEM) generates reactive gaseous mercury (RGM) which plays an important role in the atmospheric mercury cycle by enhancing the rate of mercury deposition to ecosystems. However, the primary GEM oxidants, and the chemical composition of RGM are poorly known. Using speciated mercury measurements conducted at the Mt. Bachelor Observatory since 2005 we present two previously unidentified sources of RGM to the free troposphere (FT). Firstly, we observed elevated RGM concentrations, large RGM/GEM-ratios, and anti-correlation between RGM and GEM during Asian long-rang transport events, demonstrating that RGM is formed from GEM by in-situ oxidation in some anthropogenic pollution plumes in the FT. During the Asian pollution events the measured RGM/GEM-enhancement ratios reached peak values, up to ~0.20, which are significantly larger than ratios typically measured (RGM/GEM < 0.03) in the Asian source region. Secondly, we observed very high RGM levels – the highest reported in the FT – in clean air masses that were processed upwind of Mt. Bachelor Observatory over the Pacific Ocean. The high RGM concentrations (up to 700 pg m−3), high RGM/GEM-ratios (up to 1), and very low ozone levels during these events provide observational evidence indicating significant GEM oxidation in the lower FT in some conditions.

Biomass burning, such as domestic heating, agricultural, and wild open-land fires, has a significant influence on the atmosphere at the global and, especially, at the local scale. Levoglucosan has been shown to be a good tracer for biomass burning emissions in atmospheric particulate matter, and several analytical techniques have been presented for the determination of levoglucosan from filter samples. In this paper, a novel combination of a particle-into-liquid sampler (PILS) to a high-performance anion-exchange chromatograph (HPAEC) with the detection by a mass spectrometer (MS) is presented for the online analysis of levoglucosan in ambient particles. The PILS–HPAEC–MS technique enables a fast online analysis of levoglucosan from the particulate samples. The method was tested at an urban background station in Helsinki, Finland, in winter 2011. A comparison with simultaneous levoglucosan measurements from filter samples by the HPAEC–MS was performed and it showed a good agreement between the online and offline methods. Additionally, the online levoglucosan data were compared with the biomass burning tracer fragments measured by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). As there were no local biomass burning sources close to the measurement station, online levoglucosan measurements revealed that most of the particles from biomass burning were either regionally distributed or long-range transported in the urban background of Helsinki. The average levoglucosan concentrations were relatively low (average 0.083 μg m−3) during the measurement campaign. The highest concentration peak measured for levoglucosan (1.4 μg m−3) seemed to originate from biomass burning in the Baltic countries, likely in Estonia, that was transported to Helsinki.