Towards the next generation of air quality monitoring: Persistent organic pollutants (POPs)

Hung, H.; MacLeod, M.; Guardans, R.; Scheringer, M.; Barra, R.; Harner, T.; Zhang, G.
1970 | Atmos Environ | (in press)

Persistent Organic Pollutants (POPs) are global pollutants that can migrate over long distances and bioaccumulate through food webs, posing health risks to wildlife and humans. Multilateral environmental agreements, such as the Stockholm Convention on POPs, were enacted to identify POPs and establish the conditions to control their release, production and use. A Global Monitoring Plan was initiated under the Stockholm Convention calling for POP monitoring in air as a core medium; however long temporal trends (>10 years) of atmospheric POPs are only available at a few selected sites. Spatial coverage of air monitoring for POPs has recently significantly improved with the introduction and advancement of passive air samplers. Here, we review the status of air monitoring and modeling activities and note major uncertainties in data comparability, deficiencies of air monitoring and modeling in urban and alpine areas, and lack of emission inventories for most POPs. A vision for an internationally-integrated strategic monitoring plan is proposed which could provide consistent and comparable monitoring data for POPs supported and supplemented by global and regional transport models. Key recommendations include developing expertise in all aspects of air monitoring to ensure data comparability and consistency; partnering with existing air quality and meteorological networks to leverage synergies; facilitating data sharing with international data archives; and expanding spatial coverage with passive air samplers. Enhancing research on the stability of particle-bound chemicals is needed to assess exposure and deposition in urban areas, and to elucidate long-range transport. Conducting targeted measurement campaigns in specific source areas would enhance regional models which can be extrapolated to similar regions to estimate emissions. Ultimately, reverse-modeling combined with air measurements can be used to derive “emission” as an indicator to assess environmental performance with respect to POPs on the country, region, or global level.

A High-Volume Cryosampler and Sample Purification System for Bromine Isotope Studies of Methyl Bromide

B.F. Thornton; A. Horst; D. Carrizo; H. Holmstrand; P. Andersson; P.M. Crill; Ö. Gustafsson
1970 | J. Atmos. Ocean. Technol. | 30 (2095-2107)

A system was developed for collecting from the ambient atmosphere the methyl halides CH3Cl and CH3Br in quantities sufficient for chlorine and bromine isotope analysis. The construction and operation of the novel cryogenic collection system (cryosampler) and sample purification system developed for this task are described. This study demonstrates the capability of the cryosampler by quantifying the CH3Cl and CH3Br collected from atmospheric samples and the nonfractionating bromine isotope fingerprint of CH3Br from synthetic air samples of controlled composition. An optimized cryosampler operation time of 4 h at a flow rate of 15 L min−1 is applied to yield the nearly 40 ng required for subsequent δ81Br-CH3Br analyses. The sample purification system is designed around a packed column gas chromatography–quadropole–mass spectrometry (GCqMS) system with three additional cryotraps and backflushing capacity. The system's suitability was tested by observing both the mass recovery and the lack of Δ81Br isotope fractionation induced during sample purification under varying flow rates and loading scenarios. To demonstrate that the entire system samples and dependably delivers CH3Br to the isotope analysis system without inducing isotope fractionation, diluted synthetic air mixtures prepared from standard gases were processed through the entire system, yielding a Δ81Br-CH3Br of +0.03‰ ± 0.10‰ relative to their starting composition. Finally, the combined cryosampler–purification and analysis system was applied to demonstrate the first-ever δ81Br-CH3Br in the ambient atmosphere with two samples collected in the autumn of 2011, yielding −0.08‰ ± 0.43‰ and +1.75‰ ± 0.13‰ versus standard mean ocean bromide for samples collected at a suburban Stockholm, Sweden, site.

Iron speciation in soft-water lakes and soils as determined by EXAFS spectroscopy and geochemical modeling.

Sjöstedt, C.; Persson, I.; Hesterberg, D.; Berggren Kleja, D.; Borg, H.; Gustafsson, J.P.
1970 | Geochim. Cosmochim. Acta | 105 (172-186)

Five critical questions of scale for the coastal zone

Swaney, D.P.; Humborg, C.; Emeis, K.; Kannen, A.; Silvert, W.; Tett, P.; Pastres, R.; Solidoro, C.; Yamamuro, M.; Hénocque, Y.; Nicholls, R.
1970 | Estuar Coast Shelf Sci | 96 (9-21)

Riverine nitrogen export in Swedish catchments dominated by atmospheric inputs

Eriksson Hägg, H; Humborg, C.; Swaney, D.P.; Mörth, C.-M.
1970 | Biogeochemistry

Aqueous and biotic mercury concentrations in boreal lakes: model predictions and observations. — In: Mercury Pollution: Integration and Synthesis (eds. Watras, C.J. & Huckabee, J.W.). CRC Press, Lewis Publishers Inc., Boca Raton FL, Chapter I.8, pp. 99-106.

1970 | CRC Press, Lewis Publishers, New York | ISBN: 1-56670-066-3
hg , mercury

fulltext (preview):

Erratum to ‘Biomagnification of Organic Pollutants in Benthic and Pelagic Marine Food Chains from the Baltic Sea.’

| Sci. Total Environ. | 407 (21) (5803-5804)

Size-resolved cloud condensation nuclei concentration measurements in the Arctic: two case studies from the summer of 2008

| Atmos. Chem. Phys. | 15 (13803-13817)

The Arctic is one of the most vulnerable regions affected by climate change. Extensive measurement data are needed to understand the atmospheric processes governing this vulnerability. Among these, data describing cloud formation potential are of particular interest, since the indirect effect of aerosols on the climate system is still poorly understood. In this paper we present, for the first time, size-resolved cloud condensation nuclei (CCN) data obtained in the Arctic. The measurements were conducted during two periods in the summer of 2008: one in June and one in August, at the Zeppelin research station (78°54´ N, 11°53´ E) in Svalbard. Trajectory analysis indicates that during the measurement period in June 2008, air masses predominantly originated from the Arctic, whereas the measurements from August 2008 were influenced by mid-latitude air masses. CCN supersaturation (SS) spectra obtained on the 27 June, before size-resolved measurements were begun, and spectra from the 21 and 24 August, conducted before and after the measurement period, revealed similarities between the 2 months. From the ratio between CCN concentration and the total particle number concentration (CN) as a function of dry particle diameter (Dp) at a SS of 0.4 %, the activation diameter (D50), corresponding to CCN / CN = 0.50, was estimated. D50 was found to be 60 and 67 nm for the examined periods in June and August 2008, respectively. Corresponding D50 hygroscopicity parameter (κ) values were estimated to be 0.4 and 0.3 for June and August 2008, respectively. These values can be compared to hygroscopicity values estimated from bulk chemical composition, where κ was calculated to be 0.5 for both June and August 2008. While the agreement between the 2 months is reasonable, the difference in κ between the different methods indicates a size dependence in the particle composition, which is likely explained by a higher fraction of inorganics in the bulk aerosol samples.

Madrid Statement on Poly- and Perfluoroalkyl Substances (PFASs)

| Environ. Health Perspect. | 123 (A107-A111)

Additions and corrections to ‘Predicted Distribution and Ecological Assessment of a “Segregated” Hydrofluoroether in the Japanese Environment´

| Environ. Sci. Technol. | 37 (6) (1228-1228)

An empirically derived inorganic sea spray source function incorporating sea surface temperature

| Atmos. Chem. Phys. | 15 (11047-11066)

We have developed an inorganic sea spray source function that is based upon state-of-the-art measurements of sea spray aerosol production using a temperature-controlled plunging jet sea spray aerosol chamber. The size-resolved particle production was measured between 0.01 and 10 μm dry diameter. Particle production decreased non-linearly with increasing seawater temperature (between −1 and 30 °C) similar to previous findings. In addition, we observed that the particle effective radius, as well as the particle surface, particle volume and particle mass, increased with increasing seawater temperature due to increased production of particles with dry diameters greater than 1 μm. By combining these measurements with the volume of air entrained by the plunging jet we have determined the size-resolved particle flux as a function of air entrainment. Through the use of existing parameterisations of air entrainment as a function of wind speed, we were subsequently able to scale our laboratory measurements of particle production to wind speed. By scaling in this way we avoid some of the difficulties associated with defining the "white area" of the laboratory whitecap – a contentious issue when relating laboratory measurements of particle production to oceanic whitecaps using the more frequently applied whitecap method.

The here-derived inorganic sea spray source function was implemented in a Lagrangian particle dispersion model (FLEXPART – FLEXible PARTicle dispersion model). An estimated annual global flux of inorganic sea spray aerosol of 5.9 ± 0.2 Pg yr−1 was derived that is close to the median of estimates from the same model using a wide range of existing sea spray source functions. When using the source function derived here, the model also showed good skill in predicting measurements of Na+ concentration at a number of field sites further underlining the validity of our source function.

In a final step, the sensitivity of a large-scale model (NorESM – the Norwegian Earth System Model) to our new source function was tested. Compared to the previously implemented parameterisation, a clear decrease of sea spray aerosol number flux and increase in aerosol residence time was observed, especially over the Southern Ocean. At the same time an increase in aerosol optical depth due to an increase in the number of particles with optically relevant sizes was found. That there were noticeable regional differences may have important implications for aerosol optical properties and number concentrations, subsequently also affecting the indirect radiative forcing by non-sea spray anthropogenic aerosols.

Cellular Dose of Partly Soluble Cu Particle Aerosols at the Air–Liquid Interface Using an In Vitro Lung Cell Exposure System

| J Aerosol Med Pulm Drug Deliv | 26 (2) (84-93)
air–liquid interface , cellular doses , copper particles , in vitro exposure system , nanoparticle deposition , nanoparticle dissolution , nanotoxicology

There is currently a need to develop and test in vitro systems for predicting the toxicity of nanoparticles. One challenge is to determine the actual cellular dose of nanoparticles after exposure.
In this study, human epithelial lung cells (A549) were exposed to airborne Cu particles at the air-liquid interface (ALI). The cellular dose was determined for two different particle sizes at different deposition conditions, including constant and pulsed Cu aerosol flow.
Airborne polydisperse particles with a geometric mean diameter (GMD) of 180 nm [geometric standard deviation (GSD) 1.5, concentration 10(5) particles/mL] deposited at the ALI yielded a cellular dose of 0.4-2.6 μg/cm(2) at pulsed flow and 1.6-7.6 μg/cm(2) at constant flow. Smaller polydisperse particles in the nanoregime (GMD 80 nm, GSD 1.5, concentration 10(7) particles/mL) resulted in a lower cellular dose of 0.01-0.05 μg/cm(2) at pulsed flow, whereas no deposition was observed at constant flow. Exposure experiments with and without cells showed that the Cu particles were partly dissolved upon deposition on cells and in contact with medium.
Different cellular doses were obtained for the different Cu particle sizes (generated with different methods). Furthermore, the cellular doses were affected by the flow conditions in the cell exposure system and the solubility of Cu. The cellular doses of Cu presented here are the amount of Cu that remained on the cells after completion of an experiment. As Cu particles were partly dissolved, Cu (a nonnegligible contribution) was, in addition, present and analyzed in the nourishing medium present beneath the cells. This study presents cellular doses induced by Cu particles and demonstrates difficulties with deposition of nanoparticles at the ALI and of partially soluble particles.

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