From a polar to a marine environment: has the changing Arctic led to a shift in aerosol light scattering properties?

2020 | Atmos. Chem. Phys. | 20 (13671-13686)

The study of long-term trends in aerosol optical properties is an important task to understand the underlying aerosol processes influencing the change of climate. The Arctic, as the place where climate change manifests most, is an especially sensitive region of the world. Within this work, we use a unique long-term data record of key aerosol optical properties from the Zeppelin Observatory, Svalbard, to ask the question of whether the environmental changes of the last 2 decades in the Arctic are reflected in the observations. We perform a trend analysis of the measured particle light scattering and backscattering coefficients and the derived scattering Ångström exponent and hemispheric backscattering fraction. In contrast to previous studies, the effect of in-cloud scavenging and of potential sampling losses at the site are taken explicitly into account in the trend analysis. The analysis is combined with a back trajectory analysis and satellite-derived sea ice data to support the interpretation of the observed trends. We find that the optical properties of aerosol particles have undergone clear and significant changes in the past 2 decades. The scattering Ångström exponent exhibits statistically significant decreasing of between −4.9 % yr−1 and −6.5 % yr−1 (using wavelengths of λ=450 and 550 nm), while the particle light scattering coefficient exhibits statistically significant increasing trends of between 2.6 % yr−1 and 2.9 % yr−1 (at a wavelength of λ=550 nm). The magnitudes of the trends vary depending on the season. These trends indicate a shift to an aerosol dominated more by coarse-mode particles, most likely the result of increases in the relative amount of sea spray aerosol. We show that changes in air mass circulation patterns, specifically an increase in air masses from the south-west, are responsible for the shift in aerosol optical properties, while the decrease of Arctic sea ice in the last 2 decades only had a marginal influence on the observed trends.

Atmospheric new particle formation characteristics in the Arctic as measured at Mount Zeppelin, Svalbard, from 2016 to 2018

Haebum Lee; Kwangyul Lee; Chris Rene Lunder; Radovan Krejci; Wenche Aas; Jiyeon Park; Ki-Tae Park; Bang Yong Lee; Young Jun Yoon; and Kihong Park;
2020 | Atmos. Chem. Phys. | 20 (13425-13441)

We conducted continuous measurements of nanoparticles down to 3 nm size in the Arctic at Mount Zeppelin, Ny Ålesund, Svalbard, from October 2016 to December 2018, providing a size distribution of nanoparticles (3–60 nm). A significant number of nanoparticles as small as 3 nm were often observed during new particle formation (NPF), particularly in summer, suggesting that these were likely produced near the site rather than being transported from other regions after growth. The average NPF frequency per year was 23 %, having the highest percentage in August (63 %). The average formation rate (J) and growth rate (GR) for 3–7 nm particles were 0.04 cm−3 s−1 and 2.07 nm h−1, respectively. Although NPF frequency in the Arctic was comparable to that in continental areas, the J and GR were much lower. The number of nanoparticles increased more frequently when air mass originated over the south and southwest ocean regions; this pattern overlapped with regions having strong chlorophyll a concentration and dimethyl sulfide (DMS) production capacity (southwest ocean) and was also associated with increased NH3 and H2SO4 concentration, suggesting that marine biogenic sources were responsible for gaseous precursors to NPF. Our results show that previously developed NPF occurrence criteria (low loss rate and high cluster growth rate favor NPF) are also applicable to NPF in the Arctic.

Provningsjämförelse / Proficiency Test 2020-3, Närsalter och lukt i vatten / Nutrients and odour in water

2020 | ACES rapport, Department of Environmental Science and Analytical Chemistry, Stockholm University | Report No: 41

Differences in the composition of organic aerosols between winter and summer in Beijing: a study by direct-infusion ultrahigh-resolution mass spectrometry

Steimer, SS; Patton, DJ; Vu, TV; Panagi, M; Monks, PS; Harrison, RM; Fleming, ZL; Shi, Z; Kalberer, M
2020 | Atmos. Chem. Phys. | 20 (21) (13303-13318)

This study investigates the chemical composition of PM2.5 collected at a central location in Beijing, China, during winter 2016 and summer 2017. The samples were characterised using direct-infusion negative-nano-electrospray-ionisation ultrahigh-resolution mass spectrometry to elucidate the composition and the potential primary and secondary sources of the organic fraction. The samples from the two seasons were compared with those from a road-tunnel site and an urban background site in Birmingham, UK, analysed in the course of an earlier study using the same method. There were strong differences in aerosol particle composition between the seasons, particularly regarding (poly-)aromatic compounds, which were strongly enhanced in winter, likely due to increased fossil fuel and biomass burning for heating. In addition to the seasonal differences, compositional differences between high- and low-pollution conditions were observed, with the contribution of sulfur-containing organic compounds strongly enhanced under high-pollution conditions. There was a correlation of the number of sulfur-containing molecular formulae with the concentration of particulate sulfate, consistent with a particle-phase formation process.

An overview of the uses of per- and polyfluoroalkyl substances (PFAS)

Glüge, J.; Scheringer, M.; Cousins, I.T.; DeWitt, J.C.; Goldenman, G.; Herzke, D.; Lohmann, R.; Ng, C.A.; Trier, X.; Wang Z.
2020 | Environ. Sci.-Process Impacts | 22 (2345-2373)

The High Persistence of PFAS is Sufficient for their Management as a Chemical Class

Cousins, I.T.; DeWitt, J.C.; Glüge, J.; Goldenman, G.; Herzke, D.; Lohmann, R.; Ng, C.A.; Scheringer, M.; Wang, Z.
2020 | Environ. Sci.-Process Impacts | 22 (2307-2312)

Association between Aquatic Micropollutant Dissipation and River Sediment Bacterial Communities

Coll, C.; Bier, R.; Li, Z.; Langenheder, S.; Gorokhova, E.; Sobek, A.
2020 | Environ. Sci. Technol. | 54 (22) (14380-14392)

Potential Effects on Travelers’ Air Pollution Exposure and Associated Mortality Estimated for a Mode Shift from Car to Bicycle Commuting

Nilsson Sommar, J.; Johansson, C.; Lövenheim, B.; Markstedt, A.; Strömgren, M.; Forsberg, B.
2020 | Int J Environ Res Public Health | 17

This study aims to use dispersion-modeled concentrations of nitrogen oxides (NOx)
and black carbon (BC) to estimate bicyclist exposures along a network of roads and bicycle paths.
Such modeling was also performed in a scenario with increased bicycling. Accumulated concentrations
between home and work were thereafter calculated for both bicyclists and drivers of cars. A transport
model was used to estimate trac volumes and current commuting preferences in Stockholm County.
The study used individuals’ home and work addresses, their age, sex, and an empirical model
estimate of their expected physical capacity in order to establish realistic bicycle travel distances. If car
commuters with estimated physical capacity to bicycle to their workplace within 30 min changed
their mode of transport to bicycle, >110,000 additional bicyclists would be achieved. Time-weighted
mean concentrations along paths were, among current bicyclists, reduced from 25.8 to 24.2 µg/m3 for
NOx and 1.14 to 1.08 µg/m3 for BC. Among the additional bicyclists, the yearly mean NOx dose from
commuting increased from 0.08 to 1.03 µg/m3. This would be expected to yearly cause 0.10 fewer
deaths for current bicycling levels and 1.7 more deaths for additional bicycling. This increased air
pollution impact is much smaller than the decrease in the total population.

Influence of Arctic Microlayers and Algal Cultures on Sea Spray Hygroscopicity and the Possible Implications for Mixed‐Phase Clouds

Sigurd Christiansen; Luisa Ickes; Ines Bulatovic; Caroline Leck; Benjamin J Murray; Allan K Bertram; Robert Wagner; Elena Gorokhova; Matthew E Salter; Annica ML Ekman; Merete Bilde
2020 | J. Geophys. Res.-Atmos. | 125

Remobilization of dormant carbon from Siberian Arctic permafrost during three past warming events

Jannik Martens; Birgit Wild; Francesco Muschitiello; Matt O’Regan; Martin Jakobsson; Igor Semiletov; Oleg V. Dudarev; Örjan Gustafsson
2020 | Sci. Adv. | 6 (42)

Are Fluoropolymers Really of Low Concern for Human and Environmental Health and Separate from Other PFAS?

Lohmann, R.; Cousins, I.T.; DeWitt, J.C.; Glüge, J.; Goldenman, G.; Herzke, D.; Lindstrom, A.B.; Miller, M.F.; Ng, C.A.; Patton, S.; Scheringer, M.; Trier, X.; Wang, Z.
2020 | Environ. Sci. Technol. | 54 (20) (12820-12828)

Frequent new particle formation over the high Arctic pack ice by enhanced iodine emissions

Andrea Baccarini; Linn Karlsson; Josef Dommen; Patrick Duplessis; Jutta Vüllers; Ian M. Brooks; Alfonso Saiz-Lopez; Matthew Salter; Michael Tjernström; Urs Baltensperger; Paul Zieger; Julia Schmale
2020 | Nat. Commun. | 11 (4924 ) (1-11)

In the central Arctic Ocean the formation of clouds and their properties are sensitive to the availability of cloud condensation nuclei (CCN). The vapors responsible for new particle formation (NPF), potentially leading to CCN, have remained unidentified since the first aerosol measurements in 1991. Here, we report that all the observed NPF events from the Arctic Ocean 2018 expedition are driven by iodic acid with little contribution from sulfuric acid. Iodic acid largely explains the growth of ultrafine particles (UFP) in most events. The iodic acid concentration increases significantly from summer towards autumn, possibly linked to the ocean freeze-up and a seasonal rise in ozone. This leads to a one order of magnitude higher UFP concentration in autumn. Measurements of cloud residuals suggest that particles smaller than 30 nm in diameter can activate as CCN. Therefore, iodine NPF has the potential to influence cloud properties over the Arctic Ocean.

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