Toward a Standardized Thermal-optical Protocol for Measuring Atmospheric Organic and Elemental Carbon: The EUSAAR Protocol

Thermal-optical analysis is a conventional method for classifying carbonaceous aerosols as organic carbon and elemental carbon. Unfortunately, different thermal evolution protocols result in a wide elemental carbon-to-total carbon variation up to a factor of five. In Europe, there is currently no standard procedure for determining carbonaceous aerosol fraction which implies that data from different laboratories at various sites are most likely not comparable and affected by unknown errors. In the framework of the European project EUSAAR (European Supersites for Atmospheric Aerosol Research), a comprehensive work has been carried out to investigate the causes of differences in the EC measured using different thermal evolution protocols and attempts have been devoted to assess and mitigate major positive and negative biases affecting thermal-optical analysis. Our approach to improve the accuracy of the thermal-optical discrimination between organic carbon and elemental carbon was essentially based on four goals. First, as charring correction relies on assumptions proven to be generally not true ¿e.g. pyrolic carbon is considered to evolve completely before native elemental carbon throughout the analysis¿, we sought to reduce pyrolysis to minimum levels in favour of a maximum volatilisation of organic carbon. Second, we sought to minimize the potential negative bias in EC determination caused by early release of light absorbing species at high temperature in the He-mode, including native EC or a combination of EC and pyrolitic carbon with potentially different specific cross section values. Third, we sought to minimize the potential positive bias in EC determination resulting from the slipping of residual organic carbon into the He/O2-mode and its potential evolution after the split point. Finally, we sought to reduce the uncertainty arising from the position of the OC/EC split point on the FID profile through multiple desorption steps in the He/O2-mode. Based on different types of carbonaceous PM encountered across Europe, we defined an optimised thermal evolution protocol, the EUSAAR_2 protocol, as follows: step 1 in He, 200 °C for 120 s; step 2 in He 300°C for 150s; step 3 in He 450°C for 180s; step 4 in He 650°C for 180s. For steps 1-4 in He/O2, the conditions are 500°C for 120s, 550°C for 120s, 700°C for 70s, and 850°C for 80s, respectively.JRC.H.2-Climate chang

Literature review for ODS (Ozone Depleting Substances) measurement methods and data

Stratospheric ozone absorbs most of the sun’s harmful UV radiation. The increased use of human-produced gases such as chlorofluorocarbons (CFCs) has led to a magnified springtime depletion of the protective ozone layer at both Earth’s poles, especially over Antarctica, a phenomenon well known as the ozone hole. The Montreal protocol [1] deals with substances that deplete the ozone layer (ODS) and how to reduce them (Montreal protocol, 1987 and amendments/adjustments). It covers substances with a high ozone depleting potential, CFCs and the 1st generation of CFC replacements (HCFCs). The success of the implementation of the Montreal protocol and amendments has to be demonstrated by the parties (including EU and its Member States [2]), and supported by high quality atmospheric measurements of relevant compounds. Several atmospheric data-sets are available from open-access international data bases, including 7 stations across Europe: (1) Zeppelin, Ny-Ålesund, Norway, (2) Summit, Greenland, Denmark, (3) Mace Head, Ireland, (4) Tacolneston, UK, (5) Jungfraujoch, Switzerland, (6) Monte Cimone, Italy, and (7) Lampedusa (LMP), Italy, but data quality may in some cases be unknown or questionable. High-quality long-term ambient air data are mainly coming from the AGAGE Network (http://agage.mit.edu/ [3]) and NOAA (National Oceanic and Atmospheric Administration). Ref. [3] comprising also European stations from e.g. (I) Ireland (first Agrigole (1978-1983), then Mace Head (from 1987 to present), (II) Switzerland (Jungfraujoch), from 2000 to present, (III) Norway (Ny Ålesund), from 2000 to present, and (IV) Italy (Monte Cimone) from 2002 to present. The trends in ODS concentrations measured in-situ at ground level in Europe are consistent and, similar to the trends observed in the rest of the world (see ref. [4] containing in-situ ground level measurements, flask sampling and satellite observations), especially the downwards trend of CFCs, indicating the success of the Montreal Protocol, in limiting the atmospheric abundances of ODSs [4]. The UNEP/WMO Scientific Assessment of Ozone Depletion from 2014 states [4]: “The success of the Montreal Protocol in limiting the atmospheric abundances of ODSs is now well documented”. This is confirmed by the AGAGE measurement network [3]: “International compliance with the Montreal Protocol is so far resulting in CFC and chlorocarbons abundances comparable to the target level so the Protocol is working”. In contrast, it is of concern that the concentrations of HCFCs and N2O, where the latter one being currently the single most important gas that depletes stratospheric ozone (see e.g. ref. Ravishankara et al., 2009 [15], and discussions in this report), are still increasing.JRC.H.2-Air and Climat

Long-term trends in black carbon from biomass and fossil fuel combustion detected at the JRC atmospheric observatory in Ispra

The concentrations of equivalent black carbon deriving from biomass burning [eBC]bb and fossil fuel combustion [eBC]ff have been estimated based on measurements of the aerosol light attenuation at several wavelengths (from infrared to ultraviolet) performed at the atmospheric observatory of the Joint Research Centre located in Ispra (Northern Italy). The data shows repeated seasonal cycles from 2004 to 2016, which suggests that winter time wood burning for domestic heating is the main biomass burning activity in this area. The [eBC]bb/[eBC]ff ratio has increased on average by +5%/yr over the 2007 – 2016 period. We compared these measurement-derived data with CO2 emissions estimated from EDGAR relative to biomass burning for domestic heating and fossil fuel combustion for transport (Diesel) and residential heating (coal + oil) in the 0.4°x0.4° area centred on Ispra. The data shows an increase in CO2 emissions from biomass burning compared to fossil fuel combustion from 2004 to 2008, and a rather constant ratio since then. There is no obvious correlation between the concentrations of [eBC] and the statistics on CO2 emissions from biofuel and fossil fuel combustion over the studied period. The impact of the economic crisis of 2009 on the use of biofuels for domestic heating cannot be rigorously demonstrated, neither from the measurement data nor from the emission inventory.JRC.C.5-Air and Climat

Long term trends in aerosol optical characteristics in the Po Valley, Italy

Aerosol properties have been monitored by ground-based in situ and remote sensing measurements at the station for atmospheric research located in Ispra, on the edge of the Po Valley, for almost one decade. In situ measurements are performed according to Global Atmosphere Watch recommendations, and quality is assured through the participation in regular inter-laboratory comparisons. Sunphotometer data are produced by the Aerosol Robotic Network (AERONET). Data show significant decreasing trends over the 2004–2010 period for a number of variables, including particulate matter (PM) mass concentration, aerosol scattering, backscattering and absorption coefficients, and aerosol optical thickness (AOT). In situ measurement data show no significant trends in the aerosol backscatter ratio, but they do show a significant decreasing trend of about −0.7±0.3%yr−1 in the aerosol single scattering albedo (SSA) in the visible light range. Similar trends are observed in the SSA retrieved from sun-photometer measurements. Correlations appear between in situ PM mass concentration and aerosol scattering coefficient, on the one hand, and elemental carbon (EC) concentration and aerosol absorption coefficient, on the other hand. However, no increase in the EC /PM ratio was observed, which could have explained the decrease in SSA. The application of a simple approximation to calculate the direct radiative forcing by aerosols suggests a significant diminution in their cooling effect, mainly due to the decrease in AOT. Applying the methodology we present to those sites, where the necessary suite of measurements is available, would provide important information to inform future policies for air-quality enhancement and fast climate change mitigation.JRC.H.2-Air and Climat

JRC Ispra EMEP - GAW Regional Station for Atmospheric Research - 2005 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 2005 led to annual averages of ca. 43 µg m-3 O3, 4 µg m-3 SO2, 16 µg m-3 NO2, 0.8 mg m-3 CO and 41 µg m-3 PM10. Carbonaceous species (organic matter plus elemental carbon) are the main constituents of both PM10 and PM2.5 (> 50%) followed by (NH4)2SO4 and NH4NO3 (a bit less than 20% each). 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 measured from 2004. The average particle number (from 6 nm to 10 µm) was about 10000 cm-3 in 2005. The mean (close to dry) aerosol single scattering albedo (a key parameter for determining the aerosol direct radiative forcing) was 0.80. Long-term trends (over 20 years) show decreases in sulfur concentrations and deposition, and in extreme ozone value occurrence frequency. The decreasing trends in nitrogen oxides, reduced nitrogen species, and PM concentrations are much less marked.JRC.H.2-Climate chang

Toward a Standardised Thermal-Optical Protocol for Measuring Atmospheric Organic and Elemental Carbon: The EUSAAR Protocol

Thermal-optical analysis is a conventional method for determining the carbonaceous aerosol fraction and for classifying it into organic carbon, OC, and elemental carbon, EC. Unfortunately, the different thermal evolution protocols in use can result in a wide elemental carbon-to-total carbon variation by up to a factor of five. In Europe, there is currently no standard procedure for determining the carbonaceous aerosol fraction which implies that data from different laboratories at various sites are of unknown accuracy and cannot be considered comparable. In the framework of the EU-project EUSAAR (European Supersites for Atmospheric Aerosol Research), a comprehensive study has been carried out to identify the causes of differences in the EC measured using different thermal evolution protocols; thereby the major positive and negative biases affecting thermal-optical analysis have been isolated and minimised to define an optimised protocol suitable for European aerosols. Our approach to improve the accuracy of the discrimination between OC and EC was essentially based on four goals. Firstly, charring corrections rely on faulty assumptions ¿e.g. pyrolytic carbon is considered to evolve completely before native EC throughout the analysis¿, thus we have reduced pyrolysis to a minimum by favoring volatilisation of OC. Secondly, we have minimised the potential negative bias in EC determination due to early evolution of light absorbing carbon species at higher temperatures in the He-mode, including both native EC and combinations of native EC and pyrolytic carbon potentially with different specific cross section values. Thirdly, we have minimised the potential positive bias in EC determination resulting from the incomplete evolution of OC during the He-mode which then evolves during the He/O2-mode, potentially after the split point. Finally, we have minimised the uncertainty due to the position of the OC/EC split point on the FID response profile by introducing multiple desorption steps in the He/O2-mode. Based on different types of carbonaceous PM encountered across Europe, we have defined an optimised thermal evolution protocol, the EUSAAR_2 protocol, as follows: step 1 in He, 200°C for 120s; step 2 in He 300°C for 150s; step 3 in He 450°C for 180s; step 4 in He 650°C for 180s. For steps 1-4 in He/O2, the conditions are 500°C for 120 s, 550°C for 120s, 700°C for 70s, and 850°C for 80s, respectively.JRC.DDG.H.2-Climate chang

Emissions of Carbonaceous Particulate Matter and Ultrafine Particles from Vehicles-A Scientific Review in a Cross-Cutting Context of Air Pollution and Climate Change

Featured Application Key conclusions and recommendations are proposed to enlighten decision makers in view of the next regulations on vehicle emissions in Europe and worldwide through the synergistic contexts of air quality and climate change. Airborne particulate matter (PM) is a pollutant of concern not only because of its adverse effects on human health but also on visibility and the radiative budget of the atmosphere. PM can be considered as a sum of solid/liquid species covering a wide range of particle sizes with diverse chemical composition. Organic aerosols may be emitted (primary organic aerosols, POA), or formed in the atmosphere following reaction of volatile organic compounds (secondary organic aerosols, SOA), but some of these compounds may partition between the gas and aerosol phases depending upon ambient conditions. This review focuses on carbonaceous PM and gaseous precursors emitted by road traffic, including ultrafine particles (UFP) and polycyclic aromatic hydrocarbons (PAHs) that are clearly linked to the evolution and formation of carbonaceous species. Clearly, the solid fraction of PM has been reduced during the last two decades, with the implementation of after-treatment systems abating approximately 99% of primary solid particle mass concentrations. However, the role of brown carbon and its radiative effect on climate and the generation of ultrafine particles by nucleation of organic vapour during the dilution of the exhaust remain unclear phenomena and will need further investigation. The increasing role of gasoline vehicles on carbonaceous particle emissions and formation is also highlighted, particularly through the chemical and thermodynamic evolution of organic gases and their propensity to produce particles. The remaining carbon-containing particles from brakes, tyres and road wear will still be a problem even in a future of full electrification of the vehicle fleet. Some key conclusions and recommendations are also proposed to support the decision makers in view of the next regulations on vehicle emissions worldwide

Comparison of source apportionment approaches and analysis of non-linearity in a real case model application

Abstract. The response of particulate matter (PM) concentrations to emission reductions was analysed by assessing the results obtained with two different source apportionment approaches. The brute force (BF) method source impacts, computed at various emission reduction levels using two chemical transport models (CAMx and FARM), were compared with the contributions obtained with the tagged species (TS) approach (CAMx with the PSAT module). The study focused on the main sources of secondary inorganic aerosol precursors in the Po Valley (northern Italy): agriculture, road transport, industry and residential combustion. The interaction terms between different sources obtained from a factor decomposition analysis were used as indicators of non-linear PM10 concentration responses to individual source emission reductions. Moreover, such interaction terms were analysed in light of the free ammonia / total nitrate gas ratio to determine the relationships between the chemical regime and the non-linearity at selected sites. The impacts of the different sources were not proportional to the emission reductions, and such non-linearity was most relevant for 100 % emission reduction levels compared with smaller reduction levels (50 % and 20 %). Such differences between emission reduction levels were connected to the extent to which they modify the chemical regime in the base case. Non-linearity was mainly associated with agriculture and the interaction of this source with road transport and, to a lesser extent, with industry. Actually, the mass concentrations of PM10 allocated to agriculture by the TS and BF approaches were significantly different when a 100 % emission reduction was applied. However, in many situations the non-linearity in PM10 annual average source allocation was negligible, and the TS and BF approaches provided comparable results. PM mass concentrations attributed to the same sources by TS and BF were highly comparable in terms of spatial patterns and quantification of the source allocation for industry, transport and residential combustion. The conclusions obtained in this study for PM10 are also applicable to PM2.5

Considerations on a Definition of Nanomaterial for Regulatory Purposes

The recent EU Cosmetic Products Regulation includes a labelling obligation for nanomaterials in the list of ingredients, in order to allow consumers to make a choice. Similar provisions are now being considered for other regulations/directives, e.g. the Novel Foods Regulation. Also the European chemicals legislation REACH may need adjustments to address and control the potential risk of nanomaterials. The introduction of these provisions specific to nanomaterials requires the adoption of a definition of the term "nanomaterial". This need is also acknowledged by the European Parliament which has called for a comprehensive science-based definition in Community legislation. This report reviews and discusses issues and challenges related to a definition of "nanomaterial". It gives a short overview about what may be considered as nanomaterials, their novel properties and applications. The need for a definition of nanomaterial is discussed, and the question of what should be achieved by a definition is addressed. The report gives an overview of definitions by international, national and European institutions, and lists approaches used in European legislation. It summarises the advantages and shortcomings of different elements typically used in available definitions, regarding their applicability in a regulatory context. The following three key elements are identified as being crucial in achieving a single, enforceable definition of nanomaterial: (i) the term "material", (ii) the nanoscale, and (iii) specific nanoscale properties. Material and nanoscale should both preferably be defined precisely in order to ease enforceability. This implies the introduction of precise nanoscale limits and instructions on how such limits can be applied to nanoscale materials with size distributions. Size-derived properties, nanostructured features, nanoscale materials incorporated in a matrix and the origin of the material are also issues to be considered. Key words: nanomaterial, definition, nanoscale, physico-chemical properties, Cosmetic Products Regulation, REACH.JRC.DG.I.5-Nanobioscience

Better constraints on sources of carbonaceous aerosols using a combined 14C – macro tracer analysis in a European rural background site

The source contributions to carbonaceous PM2.5 aerosol were investigated at a European background site at the edge of the Po Valley, in Northern Italy, during the period January - December 2007. Carbonaceous aerosol was described as the sum of eight source components: primary (1) and secondary (2) biomass burning organic carbon, biomass burning elemental carbon (3), primary (4) and secondary (5) fossil fuel burning organic carbon, fossil fuel burning elemental carbon (6), primary (7) and secondary (8) biogenic organic carbon. The concentration of each component was quantified using a set of macro tracers (organic carbon OC, elemental carbon EC, and levoglucosan), micro tracers (arabitol and mannitol), and 14C measurements. This was the first time that 14C measurements were performed on a long time series of data able to represent the entire annual cycle. This set of 6 tracers, together with assumed uncertainty ranges of the ratios of OC-to-EC, and the fraction of modern carbon in the 8 source categories, provides strong constraints to the source contributions to carbonaceous aerosol. The uncertainty of contributions was assessed with a Quasi-Monte Carlo (QMC) method accounting for the variability of OC and EC emission factors, and the uncertainty of reference fractions of modern carbon. During winter biomass burning composed 50% of the total carbon (TC) concentration, while in summer secondary biogenic OC accounted for 45% of TC. The contribution of primary biogenic aerosol particles was negligible during the entire year. Moreover, aerosol associated with fossil fuel burning represented 26% and 43% of TC in winter and summer, respectively. The comparison of source apportionment results in different urban and rural areas showed that the sampling site was mainly affected by local aerosol sources during winter and regional air masses from the nearby Po Valley in summer. This observation was further confirmed by back-trajectory analysis applying the Potential Source Contribution Function method to identify potential source regions. The contribution of secondary organic aerosol (SOA) to the organic mass (OM) was significant during the entire year. SOA accounted for 23% and 83% of OM during winter and summer, respectively. While the summer SOA was dominated by biogenic sources, winter SOA was mainly due to biomass and fossil fuel burning. This indicates that the oxidation of intermediate volatility organic compounds co-emitted with primary organics is a significant source of SOA, as suggested by recent model results and Aerosol Mass Spectrometer measurements in urban regions. Comparison with previous global model simulations, indicates a strong underestimate of wintertime primary aerosol emissions in this region.JRC.H.2-Air and Climat