J.-P. Putaud

Advances in characterization of size‐resolved organic matter in marine aerosol over the North Atlantic

0.80 m gm � 3 , the remainder being non-sea-salt (nss) sulphate, 0.03 ± 0.01 m gm � 3 , and nitrate, 0.13 ± 0.04 m gm � 3 . By comparison, the mass of sea salt, nss sulphate, and nitrate in the submicron mode is found to be 0.39 ± 0.08 m gm � 3 , 0.26 ± 0.04 m gm � 3 , and 0.02 ± 0.01 m gm � 3 , respectively. Water-soluble organic carbon (WSOC) is observed in the submicron mode with a mass concentration of 0.25 ± 0.04 m gm � 3 , comparable to that of nss sulphate, and in the supermicron mode with a mass concentration of 0.17 ± 0.04 m gm � 3 . The WSOC to total carbon (TC) ratio is found to be 0.20 ± 0.12 for the submicron fraction and 0.29 ± 0.08 for the supermicron fraction, while the black carbon (BC) to TC ratio is, on average, 0.032 ± 0.001 for both aerosol modes. The remaining carbon, water-insoluble organic carbon, contributes 0.66 ± 0.11 m gm � 3 and 0.26 ± 0.06 m gm � 3 to the submicron and supermicron modes, respectively and, thus, represents the dominant submicron aerosol species. Furthermore, the WSOC chemical composition comprises mainly aliphatic and only partially oxidized species and humiclike substances, resulting in appreciable surface-active properties. The observed organic matter chemical features (size-dependent concentration, hydrophobic nature of a substantial fraction of the organic matter, and low oxidized and surface-active WSOC species) are consistent with the hypothesis of a primary marine source; bubble-bursting processes, occurring at the surface of the North Atlantic Ocean during phytoplankton blooms, effectively transfer organic matter into marine aerosol particles, particularly enriching the fine-aerosol fraction. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry;

Chemical mass closure and assessment of the origin of the submicron aerosol in the marine boundary layer and the free troposphere at Tenerife during ACE-2

The organic, inorganic, mineral content and mass concentration of the submicron aerosol were measured in June−July 1997 on Tenerife in the marine boundary layer (MBL) and the free troposphere (FT). Aerosol size distributions were measured simultaneously at the same sites. The submicron aerosol mass concentrations derived from the chemical composition and calculated from the number size distributions agreed within the experimental uncertainties both in the MBL (±47%) and the FT (±75%). However, the analytical uncertainties in the concentration of organic compounds (OC) for the average sample collected in the MBL (-97, +77%) and the FT (±74%) were high. The average contribution of aerosol various components to the submicron aerosol mass were calculated for different air masses. The absolute uncertainties in these contributions were calculated by adding random uncertainties quadratically and possibly systematic errors in a conservative way. In the unperturbed MBL, the aerosol average composition (± the absolute uncertainty in the contribution) was 37 (-3, +9)% for non-sea-salt SO42-+ NH4+, 21 (-2, +10)% for sea-salt, and 20 (-7, +11)% OC (N=19). In the unperturbed FT, OC and SO42- accounted for 43 (±20)% and 32 (-5, +3)% of the submicron aerosol mass, respectively (N=15). Considering these aerosol compositions, we suggest that the source for the FT aerosol could be the transport of continental aerosol through precipitating convective clouds. A simple budget calculation shows, that in background conditions, the MBL and FT aerosol compositions are consistent with the hypothesis that the MBL aerosol is formed by the dilution of continental aerosol by FT air, modified by deposition and condensation of species of oceanic origin. Dramatic continental aerosol outbreaks were observed in both the MBL and the FT. The aerosol outbreaks in the MBL were due to transport of polluted air masses from Europe. They were characterized mainly by increases in SO42-+ NH4+, making up 75 (-5, +19)% of the submicron aerosol mass. The aerosol outbreaks in the FT were due to advection of desert dust, probably mixed with pollution aerosol.

Seasonal Characteristics of the Physicochemical Properties of North Atlantic Marine Atmospheric Aerosols

The aerosol size distribution modal diameters show seasonal variations, 0.031 mm in winter and 0.049 mm in summer for the Aitken mode and 0.103 mm in winter and 0.177 mm in summer for the accumulation mode. The accumulation mode mass also showed a seasonal variation, minimum in winter and maximum in summer. A supermicron sized particle mode was found at 2 mm for all seasons showing 30% higher mass concentration during winter than summer resulting from higher wind speed conditions. Chemical analysis showed that the concentration of sea salt has a seasonal pattern, minimum in summer and maximum in winter because of a dependency of sea-salt load on wind speeds. By contrast, the non-sea-salt (nss) sulphate concentration in fine mode particles exhibited lower values during winter and higher values during midsummer. The water soluble organic carbon (WSOC) and total carbon (TC) analysis also showed a distinctive seasonal pattern. The WSOC concentration during the high biological activity period peaked at 0.2 mgC m A3 , while it was lower than 0.05 mgC m A3 during the low biological activity period. The aerosol light scattering coefficient showed a minimum value of 5.5 Mm A1 in August and a maximum of 21 Mm A1 in February. This seasonal variation was due to the higher contribution of sea salt in the MBL during North Atlantic winter. By contrast, aerosols during late spring and summer exhibited larger angstrom parameters than winter, indicating a large contribution of the biogenically driven fine or accumulation modes. Seasonal characteristics of North Atlantic marine aerosols suggest an important link between marine aerosols and biological activity through primary production of marine aerosols.

Anthropogenic black carbon and fine aerosol distribution over Europe

We present a model simulation for the year 1995 accounting for primary particles, which are an important component of fine aerosols over Europe. A new emission inventory for black carbon, (BC) was developed on the basis of the recent European emission inventory of anthropogenic primary particulate matter (Coordinated European Programme on Particulate Matter Emission Inventories, Projections and Guidance (CEPMEIP)). The annual BC emissions of Europe and the former Soviet Union for 1995 are estimated at 0.47 and 0.26 Tg C, respectively, with highest contributions from transport (off-road and on-road) and households. Modeled BC concentrations range from ≤0.05 μtg/m 3 in remote regions to more than 1 μtg/m3 over densely populated areas. The modeled BC concentration is about 25% of the total primary aerosol concentration. The primary aerosol fields were combined with previously calculated secondary aerosol concentrations to obtain an estimate of the total anthropogenic fine aerosol distribution. Modeled BC levels contribute only 4 10% to fine aerosol mass, whereas sulphate and nitrate contribute 25-50 and 5-35%, respectively. Comparison with experimental data revealed that the model underestimates PM2.5 levels, mostly caused, by the underprediction of total carbonaceous material (BC and OC) by a factor of e12. The underestimation can partly be explained by the influence of local emissions, measurement uncertainties, natural sources, and representation of wet deposition. However, the uncertainties associated with the emission inventory for BC (and total PM) may be the most important cause for the discrepancy. In comparison with previous studies, our BC emission estimate is a factor of 2 lower, caused by the choice of more recent emission factors. Therefore a better knowledge of emission factors is urgently needed to. estimate the BC (and PM) emissions reliably. Copyright 2004 by the American Geophysical Union.

JRC Ispra EMEP - GAW Regional Station for Atmospheric Research: 2010 Report

The aim of the JRC-Ispra station for atmospheric research (45°49’N, 8°38’E) is to monitor atmospheric parameters (pollutant concentrations and fluxes, atmospheric particle chemical composition, number size distribution and optical properties) to contribute in assessing the impact of European policies on air pollution and climate change. The station has been operated continuously since November 1985, with a gap in gas phase data due to a severe breakdown of the data acquisition system in 2003 though. The measurements performed in 2007 led to annual averages of ca. 32 μg m O3, 0.8 μg m SO2, 21 μg m NO2 and 30 μg m PM10. Carbonaceous species (organic matter plus elemental carbon) are the main constituents of PM2.5 (> 55 %) followed by NH4NO3 (20-30 %) and (NH4)2SO4 (10-20 %). The measurements confirmed the seasonal variations observed over the previous years, mainly driven by meteorology rather than by changes in emissions. Aerosol physical and optical properties were also measured in 2007. The average particle number (from 10 nm to 10 μm) was about 9200 cm in 2007. The mean (close to dry) aerosol single scattering albedo (0.79) was low compared to the values generally observed in Europe, which means that the cooling effect of aerosols is reduced in our region compared to others. Long-term trends (over 20 years) show consistent decreases in sulfur concentrations and deposition, PM mass concentration (-0.9 μg m yr) and in extreme ozone value occurrence frequency. The decreasing trends in oxidised and reduced nitrogen species are much less pronounced. However, historical minimum in NO3, NH4, (and SO4) wet deposition, as well as in O3 pollution indicators (AOT40 and SOMO35) were observed in 2007. How to obtain EU publications Our priced publications are available from EU Bookshop (http://bookshop.europa.eu), where you can place an order with the sales agent of your choice. The Publications Office has a worldwide network of sales agents. You can obtain their contact details by sending a fax to (352) 29 29-42758.

Novel insights on new particle formation derived from a pan-european observing system

The formation of new atmospheric particles involves an initial step forming stable clusters less than a nanometre in size (<~1 nm), followed by growth into quasi-stable aerosol particles a few nanometres (~1–10 nm) and larger (>~10 nm). Although at times, the same species can be responsible for both processes, it is thought that more generally each step comprises differing chemical contributors. Here, we present a novel analysis of measurements from a unique multi-station ground-based observing system which reveals new insights into continental-scale patterns associated with new particle formation. Statistical cluster analysis of this unique 2-year multi-station dataset comprising size distribution and chemical composition reveals that across Europe, there are different major seasonal trends depending on geographical location, concomitant with diversity in nucleating species while it seems that the growth phase is dominated by organic aerosol formation. The diversity and seasonality of these events requires an advanced observing system to elucidate the key processes and species driving particle formation, along with detecting continental scale changes in aerosol formation into the future.