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A first direct intercomparison of aerosol vertical profiles from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations, performed during the Cabauw Intercomparison Campaign of Nitrogen Dioxide measuring Instruments (CINDI) in summer 2009, is presented. Five out of 14 participants of the CINDI campaign reported aerosol extinction profiles and aerosol optical thickness (AOT) as deduced from observations of differential slant column densities of the oxygen collision complex (O4) at different elevation angles. Aerosol extinction vertical profiles and AOT are compared to backscatter profiles from a ceilometer instrument and to sun photometer measurements, respectively. Furthermore, the near-surface aerosol extinction coefficient is compared to in situ measurements of a humidity-controlled nephelometer and dry aerosol absorption measurements. The participants of this intercomparison exercise use different approaches for the retrieval of aerosol information, including the retrieval of the full vertical profile using optimal estimation and a parametrised approach with a prescribed profile shape. Despite these large conceptual differences, and also differences in the wavelength of the observed O4 absorption band, good agreement in terms of the vertical structure of aerosols within the boundary layer is achieved between the aerosol extinction profiles retrieved by the different groups and the backscatter profiles observed by the ceilometer instrument. AOTs from MAX-DOAS and sun photometer show a good correlation (R>0.8), but all participants systematically underestimate the AOT. Substantial differences between the near-surface aerosol extinction from MAX-DOAS and from the humidified nephelometer remain largely unresolved. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) confer a wide range of optical properties to pigments/inks. With new products and applications entering the market, the airborne emissions of QDs-incorporating inks during usage stage at consumer scale (e.g. household printing) and their corresponding impacts towards human health and the environment need to be investigated. In the present work Cadmium Telluride (CdTe) QDs have been selected as a case study. The targets of this study comprise: (i) the characterization under controlled conditions of the emissions during inkjet printing of a prototype of a CdTe QDs nanoadditivated ink and (ii) the assessment of the feasibility to derive human health and freshwater effect factors (EF) for potentially released CdTe QDs with the USEtox® consensus model. Mean particle size after 60 minutes inkjet printing corresponded to 59.52 nm. For human health EF calculation an extrapolation to the human EF of other nanomaterials has been proposed considering CdTe QDs’ specific surface area whereas for the calculation of the freshwater EF, few of the data available have revealed suitable. A generic constraint to calculate both EFs for CdTe QDs released throughout the life cycle of a product incorporating them is related to the absence of information corresponding to their specific (eco)toxicological impacts.

Even if it has been claimed that Life Cycle Assessment is an essential tool to analyze, evaluate, understand and manage the environmental and health impacts of nanotechnology, few studies incorporate characterization factors (CFs) for human toxicity and freshwater ecotoxicity accounting for the impacts of engineered nanomaterials (ENMs) beyond their manufacturing stage. The objective of the present work consisted in identifying the correspondence between the information required and outputs provided by the USEtox® consensus model (which is not nanospecific) and the SimpleBox4Nano model (which accounts for nanospecific processes, e.g. aggregation, attachment and dissolution for Fate Factor derivatization) in order to assess the possibility of integrating the two to derive size-dependent CFs for the varying sizes of ENMs throughout their life cycle. The possibility to combine and integrate the two models appeared to be limited since there is no absolute correspondence between the two of them.

Observations of aerosol chemical composition in Cabauw, the Netherlands, are presented for two intensive measurement periods in May 2008 and March 2009. Submicron aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and is compared to observations from aerosol size distribution measurements as well as composition measurements with a Monitor for AeRosol and GAses (MARGA) based instrument and a Thermal-Desorption Proton-Transfer-Reaction Mass- Spectrometer (TD-PTR-MS). An overview of the data is presented and the data quality is discussed. In May 2008 enhanced pollution was observed with organics contributing 40% to the PM1 mass. In contrast the observed average mass loading was lower in March 2009 and a dominance of ammonium nitrate (42 %) was observed. The semi-volatile nature of ammonium nitrate is evident in the diurnal cycles with maximum concentrations observed in the morning hours in May 2008 and little diurnal variation observed in March 2009. Size dependent composition data from AMS measurements are presented and show a dominance of organics in the size range below 200 nm. A higher O:C ratio of the organics is observed for May 2008 than for March 2009. Together with the time series of individual tracer ions this shows the dominance of OOA over HOA in May 2008. [ABSTRACT FROM AUTHOR]

Observations of aerosol chemical composition in Cabauw, the Netherlands, are presented for two intensive measurement periods in May 2008 and March 2009. Submicron aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and is compared to observations from aerosol size distribution measurements as well as composition measurements with a Monitor for AeRosol and GAses (MARGA) based instrument and a Thermal-desorption Proton-transfer-reaction Mass-spectrometer (TD-PTR-MS). An overview of the data is presented and the data quality is discussed. In May 2008 enhanced pollution was observed with organics contributing 40% to the PM mass. In contrast the observed average mass loading was lower in March 2009 and a dominance of ammonium nitrate (42%) was observed. The semi-volatile nature of ammonium nitrate is evidenced in the diurnal cycles with maximum concentrations observed in the morning hours in May 2008 and little diurnal variation observed in March 2009. Size dependent composition data from AMS measurements are presented and show a dominance of organics in the size range below 200 nm. [ABSTRACT FROM AUTHOR]

We present comprehensive results on continuous atmospheric cluster and particle measurements in the size range ~1-42 nm within the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) project. We focused on characterizing the spatial and temporal variation of new particle formation events and relevant particle formation parameters across Europe. Different types of air ion and cluster mobility spectrometers were deployed at 12 field sites across Europe from March 2008 to May 2009. The measurements were conducted in a wide variety of environments, including coastal and continental locations as well as sites at different altitudes (both in the boundary layer and the free troposphere). New particle formation events were detected at all of the 12 field sites during the year-long measurement period. From the data, nucleation and growth rates of newly formed particles were determined for each environment. In a case of parallel ion and neutral cluster measurements, we could also estimate the relative contribution of ion-induced and neutral nucleation to the total particle formation. The formation rates of charged particles at 2 nm accounted for 1-30% of the corresponding total particle formation rates. As a significant new result, we found out that the total particle formation rate varied much more between the different sites than the formation rate of charged particles. This work presents, so far, the most comprehensive effort to experimentally characterize nucleation and growth of atmospheric molecular clusters and nanoparticles at ground-based observation sites on a continental scale. [ABSTRACT FROM AUTHOR]

Long-term measurements of PM 2.5 mass concentrations and aerosol particle size distributions from 2008 to 2015, as well as hygroscopicity measurements conducted over one year (2008–2009) at Cabauw, The Netherlands, are compiled here in order to provide a comprehensive dataset for understanding the trends and annual variabilities of the atmospheric aerosol in the region. PM 2.5 concentrations have a mean value of 14.4 μg m -3 with standard deviation 2.1 μg m -3 , and exhibit an overall decreasing trend of −0.74 μg m -3 year -1 . The highest values are observed in winter and spring and are associated with a shallower boundary layer and lower precipitation, respectively, compared to the rest of the seasons. Number concentrations of particles smaller than 500 nm have a mean of 9.2 × 10 3 particles cm -3 and standard deviation 4.9 × 10 3 particles cm -3 , exhibiting an increasing trend between 2008 and 2011 and a decreasing trend from 2013 to 2015. The particle number concentrations exhibit highest values in spring and summer (despite the increased precipitation) due to the high occurrence of nucleation-mode particles, which most likely are formed elsewhere and are transported to the observation station. Particle hygroscopicity measurements show that, independently of the air mass origin, the particles are mostly externally mixed with the more hydrophobic mode having a mean hygroscopic parameter κ of 0.1 while for the more hydrophilic mode κ is 0.35. The hygroscopicity of the smaller particles investigated in this work (i.e., particles having diameters of 35 nm) appears to increase during the course of the nucleation events, reflecting a change in the chemical composition of the particles. [ABSTRACT FROM AUTHOR]