scholarly journals Annual variability of ice nucleating particle concentrations at different Arctic locations

2018 ◽  
Author(s):  
Heike Wex ◽  
Lin Huang ◽  
Wendy Zhang ◽  
Hayley Hung ◽  
Rita Traversi ◽  
...  
Keyword(s):  
High Temperatures ◽  
Active Material ◽  
The Arctic ◽  
Research Station ◽  
Back Trajectories ◽  
Source Areas ◽  
Highly Active ◽  
Data Coverage ◽  
One Year ◽  
North Greenland

Abstract. Number concentrations of ice nucleating particles (NINP) in the Arctic were derived from ground-based filter samples. Examined samples had been collected in Alert (Nunavut, Northern Canadian Archipelago on Ellesmere Island), Utqiagvik, formerly known as Barrow (Alaska), Ny Ålesund (Svalbard) and at the Villum Research Station (VRS, North Greenland). For the former two stations, examined filters span a full yearly cycle. For VRS, 10 weekly samples, mostly from different month of one year, were included. Samples from Ny Ålesund were collected during the months from March until September of one year. At all four stations, highest concentrations were found in the summer months from roughly June to September. For those stations with sufficient data coverage, an annual cycle can be seen. The spectra of NINP observed at the highest temperatures, i.e., those obtained for summer month, showed the presence of INP that nucleate ice up to − 5 °C. It is know from literature that ice activivity observed at such high temperatures indicates the presence of ice active material of biogenic origin. Spectra observed at the lowest temperatures, i.e., those derived for winter month, were on the lower end of respective values reported in literature. An analysis concerning the origin of INP that were ice active at high temperatures was carried out, using back-trajectories and satellite information. Both, terrestrial locations in the Arctic and the adjacent sea were found to be possible source areas for highly active INP.

scholarly journals Annual variability of ice-nucleating particle concentrations at different Arctic locations

2019 ◽  
Vol 19 (7) ◽  
pp. 5293-5311 ◽  
Author(s):  
Heike Wex ◽  
Lin Huang ◽  
Wendy Zhang ◽  
Hayley Hung ◽  
Rita Traversi ◽  
...  
Keyword(s):  
High Temperatures ◽  
Active Material ◽  
Ellesmere Island ◽  
The Arctic ◽  
Research Station ◽  
Back Trajectories ◽  
Source Areas ◽  
Highly Active ◽  
Data Coverage ◽  
One Year

Abstract. Number concentrations of ice-nucleating particles (NINP) in the Arctic were derived from ground-based filter samples. Examined samples had been collected in Alert (Nunavut, northern Canadian archipelago on Ellesmere Island), Utqiaġvik, formerly known as Barrow (Alaska), Ny-Ålesund (Svalbard), and at the Villum Research Station (VRS; northern Greenland). For the former two stations, examined filters span a full yearly cycle. For VRS, 10 weekly samples, mostly from different months of one year, were included. Samples from Ny-Ålesund were collected during the months from March until September of one year. At all four stations, highest concentrations were found in the summer months from roughly June to September. For those stations with sufficient data coverage, an annual cycle can be seen. The spectra of NINP observed at the highest temperatures, i.e., those obtained for summer months, showed the presence of INPs that nucleate ice up to −5 ∘C. Although the nature of these highly ice-active INPs could not be determined in this study, it often has been described in the literature that ice activity observed at such high temperatures originates from the presence of ice-active material of biogenic origin. Spectra observed at the lowest temperatures, i.e., those derived for winter months, were on the lower end of the respective values from the literature on Arctic INPs or INPs from midlatitude continental sites, to which a comparison is presented herein. An analysis concerning the origin of INPs that were ice active at high temperatures was carried out using back trajectories and satellite information. Both terrestrial locations in the Arctic and the adjacent sea were found to be possible source areas for highly active INPs.

Investigations of past climate and sea-ice variability in the fjord area by Station Nord, eastern North Greenland

1969 ◽  
Vol 35 ◽  
pp. 67-70 ◽  
Author(s):  
Niels Nørgaard-Pedersen ◽  
Sofia Ribeiro ◽  
Naja Mikkelsen ◽  
Audrey Limoges ◽  
Marit-Solveig Seidenkrantz
Keyword(s):  
Sea Ice ◽  
Outer Part ◽  
Late Summer ◽  
Field Work ◽  
The Arctic ◽  
Research Station ◽  
Fjord System ◽  
Sea Bottom ◽  
Satellite Radar ◽  
North Greenland

The marine record of the Independence–Danmark fjord system extending out to the Wandel Hav in eastern North Greenland (Fig. 1A) is little known due to the almost perennial sea-ice cover, which makes the region inaccessible for research vessels (Nørgaard-Pedersen et al. 2008), and only a few depth measurements have been conducted in the area. In 2015, the Villum Research Station, a new logistic base for scientific investigations, was opened at Station Nord. In contrast to the early exploration of the region, it is now possible to observe and track the seasonal character and changes of ice in the fjord system and the Arctic Ocean through remote sensing by satellite radar systems. Satellite data going back to the early 1980s show that the outer part of the Independence–Danmark fjord system is characterised by perennial sea ice whereas both the southern part of the fjord system and an area 20–30 km west of Station Nord are partly ice free during late summer (Fig. 1B). Hence, marine-orientated field work can be conducted from the sea ice using snow mobiles, and by drilling through the ice to reach the underlying water and sea bottom.

scholarly journals Pan-Arctic aerosol number size distributions: seasonality and transport patterns

2017 ◽  
Vol 17 (13) ◽  
pp. 8101-8128 ◽  
Author(s):  
Eyal Freud ◽  
Radovan Krejci ◽  
Peter Tunved ◽  
Richard Leaitch ◽  
Quynh T. Nguyen ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Regional Scale ◽  
Arctic Region ◽  
The Arctic ◽  
Research Station ◽  
Size Distributions ◽  
Back Trajectories ◽  
Accumulation Mode ◽  
Source Regions ◽  
The Arctic Ocean

Abstract. The Arctic environment has an amplified response to global climatic change. It is sensitive to human activities that mostly take place elsewhere. For this study, a multi-year set of observed aerosol number size distributions in the diameter range of 10 to 500 nm from five sites around the Arctic Ocean (Alert, Villum Research Station – Station Nord, Zeppelin, Tiksi and Barrow) was assembled and analysed.A cluster analysis of the aerosol number size distributions revealed four distinct distributions. Together with Lagrangian air parcel back-trajectories, they were used to link the observed aerosol number size distributions with a variety of transport regimes. This analysis yields insight into aerosol dynamics, transport and removal processes, on both an intra- and an inter-monthly scale. For instance, the relative occurrence of aerosol number size distributions that indicate new particle formation (NPF) event is near zero during the dark months, increases gradually to  ∼ 40 % from spring to summer, and then collapses in autumn. Also, the likelihood of Arctic haze aerosols is minimal in summer and peaks in April at all sites.The residence time of accumulation-mode particles in the Arctic troposphere is typically long enough to allow tracking them back to their source regions. Air flow that passes at low altitude over central Siberia and western Russia is associated with relatively high concentrations of accumulation-mode particles (Nacc) at all five sites – often above 150 cm−3. There are also indications of air descending into the Arctic boundary layer after transport from lower latitudes.The analysis of the back-trajectories together with the meteorological fields along them indicates that the main driver of the Arctic annual cycle of Nacc, on the larger scale, is when atmospheric transport covers the source regions for these particles in the 10-day period preceding the observations in the Arctic. The scavenging of these particles by precipitation is shown to be important on a regional scale and it is most active in summer. Cloud processing is an additional factor that enhances the Nacc annual cycle.There are some consistent differences between the sites that are beyond the year-to-year variability. They are the result of differences in the proximity to the aerosol source regions and to the Arctic Ocean sea-ice edge, as well as in the exposure to free-tropospheric air and in precipitation patterns – to mention a few. Hence, for most purposes, aerosol observations from a single Arctic site cannot represent the entire Arctic region. Therefore, the results presented here are a powerful observational benchmark for evaluation of detailed climate and air chemistry modelling studies of aerosols throughout the vast Arctic region.

scholarly journals Pan-Arctic Aerosol Number Size Distributions: Seasonality and Transport Patterns

2017 ◽  
Author(s):  
Eyal Freud ◽  
Radovan Krejci ◽  
Peter Tunved ◽  
Richard Leaitch ◽  
Quynh T. Nguyen ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Annual Cycle ◽  
Arctic Region ◽  
The Arctic ◽  
Research Station ◽  
Size Distributions ◽  
Back Trajectories ◽  
Accumulation Mode ◽  
Source Regions ◽  
The Arctic Ocean

Abstract. The Arctic environment has an amplified response to global climatic change. It is sensitive to human activities that mostly take place elsewhere. For this study, a multi-year set of observed aerosol number size distributions in the diameter range of 10 to 500 nm from five sites around the Arctic Ocean (Alert, Villum Research Station – Station Nord, Zeppelin, Tiksi and Barrow) was assembled and analysed. A cluster analysis of the aerosol number size distributions, revealed four distinct distributions. Together with Lagrangian air parcel back-trajectories, they were used to link the observed aerosol number size distributions with a variety of transport regimes. This analysis yields insight into aerosol dynamics, transport and removal processes, on both an intra- and inter-monthly scales. For instance, the relative occurrence of aerosol number size distributions that indicate new particle formation (NPF) event is near zero during the dark months, and increases gradually to ~ 40 % from spring to summer, and then collapses in autumn. Also, the likelihood of Arctic Haze aerosols is minimal in summer and peaks in April at all sites. The residence time of accumulation-mode particles in the Arctic troposphere is typically long enough to allow tracking them back to their source regions. Air flow that passes at low altitude over central Siberia and Western Russia is associated with relatively high concentrations of accumulation-mode particles (Nacc) at all five sites – often above 150 cm−3. There are also indications of air descending into the Arctic boundary layer after transport from lower latitudes. The analysis of the back-trajectories together with the meteorological fields along them indicates that the main driver of the Arctic annual cycle of Nacc, on the larger scale, is when atmospheric transport covers the source regions for these particles in the 10-day period preceding the observations in the Arctic. The scavenging of these particles by precipitation is shown to be important on a regional scale and it is most active in summer. Cloud processing is an additional factor that enhances the Nacc annual cycle. There are some consistent differences between the sites that are beyond the year-to-year variability. They are the result of differences in the proximity to the aerosol source regions and to the Arctic Ocean sea-ice edge, as well as in the exposure to free tropospheric air and in precipitation patterns – to mention a few. Hence, for most purposes, aerosol observations from a single Arctic site cannot represent the entire Arctic region. Therefore, the results presented here are a powerful observational benchmark for evaluation of detailed climate and air chemistry modelling studies of aerosols throughout the vast Arctic region.

scholarly journals Dynamics of gaseous oxidized mercury at Villum Research Station during the High Arctic summer

2021 ◽  
Author(s):  
Jakob Boyd Pernov ◽  
Bjarne Jensen ◽  
Andreas Massling ◽  
Daniel Charles Thomas ◽  
Henrik Skov
Keyword(s):  
Meteorological Data ◽  
High Arctic ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Research Station ◽  
Cold Temperatures ◽  
Air Mass ◽  
Back Trajectories ◽  
Arctic Summer ◽  
Gaseous Oxidized Mercury

Abstract. While much research has been devoted to the subject of gaseous elemental mercury (GEM) and gaseous oxidized mercury (GOM) in the Arctic spring, during atmospheric mercury depletion events, few studies have examined the behavior of GOM in the High Arctic summer. GOM, once introduced into the ecosystem, can pose a threat to human and wildlife health, though there remain large uncertainties regarding the transformation, deposition, and assimilation of mercury into the ecosystem. Therefore, to further our understanding of the dynamics of gaseous oxidized mercury in the High Arctic during the late summer, we performed measurements of GEM and GOM along with meteorological parameters, atmospheric constituents, and air mass history during two summer campaigns in 2019 and 2020 at Villum Research Station (Villum) in Northeastern Greenland. Five events of enhanced GOM concentrations were identified and investigated in greater detail. The origin of these events was identified, through analysis of air mass back-trajectories, associated meteorological data, and other atmospheric constituents, to be the cold, dry free troposphere. These events were associated with low RH, limited precipitation, cold temperatures, and intense sunlight along the trajectory path. Events were positively correlated with ozone, aerosol particle number, and black carbon mass concentration, which were interpreted as an indication of tropospheric air masses. This work aims to provide a better understanding of the dynamics of GOM during the High Arctic summer.

scholarly journals The variability in Gaseous Elemental Mercury at Villum Research Station, Station Nord in North Greenland from 1999 to 2017

2020 ◽  
Author(s):  
Henrik Skov ◽  
Jens Hjorth ◽  
Claus Nordstrøm ◽  
Bjarne Jensen ◽  
Christel Christoffersen ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Elemental Mercury ◽  
Atmospheric Mercury ◽  
The Arctic ◽  
Back Trajectory ◽  
Research Station ◽  
Emission Reductions ◽  
Gaseous Elemental Mercury ◽  
Mercury Analysis ◽  
North Greenland

Abstract. Mercury is ubiquitous in the atmosphere and atmospheric transport is an important source for this element in the Arctic. Measurements of gaseous elemental mercury (GEM) have been carried out at the Villum Research Station (Villum) at Station Nord, situated in north Greenland. The measurements cover the period 1999–2017 with a gap in the data for the period 2003–2008 (for a total of 11 years). The measurements were compared with model results from the Danish Eulerian Hemispheric Model (DEHM) model that describes the contribution from direct anthropogenic transport, marine emission and general background concentration. The percentage of time spent over different surfaces was calculated by back-trajectory analysis and the reaction kinetics was determined by comparison with ozone. The GEM measurements were analysed for trends, both seasonal and annually. The only significant trend found was a negative one for the winter months. Comparison of the measurements to simulations using the Danish Eulerian Hemispheric Model (DEHM) indicated that direct transport of anthropogenic emissions of mercury accounts for between 14 and 17 % of the measured mercury. Analysis of the kinetics of the observed Atmospheric Mercury Depletion Events (AMDEs) confirms the results of a previous study at Villum of the competing reactions of GEM and ozone with Br, which suggests a lifetime of GEM on the order of a month. However, a GEM lifetime of 12 months gave the best agreement between model and measurements. The chemical lifetime is shorter and thus the apparent lifetime appears to be the result of deposition followed by reduction and reemission; for this reason the term relaxation time is preferred to lifetime for GEM. The relaxation time for GEM causes a delay between emission reductions and the effect on actual concentrations. No annual trend was found for the measured concentrations of GEM over the measurement period despite emission reductions. This is interesting and together with low direct transport of GEM to Villum, as found by the DEHM model, it shows that the dynamics of GEM is very complex. Therefore in the coming years, intensive measurement networks is highly needed to describe the global distribution of mercury in the environment as the use of models to predict future levels will still be highly uncertain. The situation is increasingly complex due to global change that most likely will change the transport patterns of mercury not only in the atmosphere but also between matrixes.

scholarly journals Potential source regions and processes of aerosol in the summer Arctic

2015 ◽  
Vol 15 (11) ◽  
pp. 6487-6502 ◽  
Author(s):  
J. Heintzenberg ◽  
C. Leck ◽  
P. Tunved
Keyword(s):  
Particle Size ◽  
Open Water ◽  
The Arctic ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Back Trajectories ◽  
Source Areas ◽  
Source Regions ◽  
Potential Source ◽  
Pack Ice

Abstract. Sub-micrometer particle size distributions measured during four summer cruises of the Swedish icebreaker Oden 1991, 1996, 2001, and 2008 were combined with dimethyl sulfide gas data, back trajectories, and daily maps of pack ice cover in order to investigate source areas and aerosol formation processes of the boundary layer aerosol in the central Arctic. With a clustering algorithm, potential aerosol source areas were explored. Clustering of particle size distributions together with back trajectories delineated five potential source regions and three different aerosol types that covered most of the Arctic Basin: marine, newly formed and aged particles over the pack ice. Most of the pack ice area with < 15% of open water under the trajectories exhibited the aged aerosol type with only one major mode around 40 nm. For newly formed particles to occur, two conditions had to be fulfilled over the pack ice: the air had spent 10 days while traveling over ever more contiguous ice and had traveled over less than 30% open water during the last 5 days. Additionally, the air had experienced more open water (at least twice as much as in the cases of aged aerosol) during the last 4 days before arrival in heavy ice conditions at Oden. Thus we hypothesize that these two conditions were essential factors for the formation of ultrafine particles over the central Arctic pack ice. In a comparison the Oden data with summer size distribution data from Alert, Nunavut, and Mt. Zeppelin, Spitsbergen, we confirmed the Oden findings with respect to particle sources over the central Arctic. Future more frequent broken-ice or open water patches in summer will spur biological activity in surface water promoting the formation of biological particles. Thereby low clouds and fogs and subsequently the surface energy balance and ice melt may be affected.

ISOLEMENT ET QUELQUES CARACTERISTIQUES D'UNE GONADOTROPHINE URINAIRE DE MÉNOPAUSE HOMOGÈNE A L'ELECTROPHORÈSE

1960 ◽  
Vol XXXV (II) ◽  
pp. 225-234 ◽  
Author(s):  
R. Bourrillon ◽  
R. Got ◽  
R. Marcy
Keyword(s):  
Sialic Acid ◽  
Histological Study ◽  
Active Material ◽  
Biologically Active ◽  
New Method ◽  
Female Rats ◽  
Mouse Uterus ◽  
Highly Active ◽  
Zone Electrophoresis ◽  
Human Menopausal Gonadotrophin

ABSTRACT A new method for preparation of Human Menopausal Gonadotrophin involves successively alcoholic precipitation, kaolin adsorption and chromatography on ion exchangers. A highly active material is obtained which corresponds to 1 mg per litre of urine and has an activity of 1 mouse uterus unit at a dose of 0.003 mg. This gonadotrophin possesses both follicle stimulating and luteinizing activities in hypophysectomized female rats, by histological study. It contains 13 % hexose, 10% hexosamine and 8.5 % sialic acid. A further purification, by zone electrophoresis on starch, gives a final product, biologically active at 0.001 mg, which behaves as an homogenous substance in free electrophoresis with mobility −4.76 × 10−5 at pH 8.6.

scholarly journals OP0034 DOES THE RISK OF VENOUS THROMBOEMBOLISM VARY WITH DISEASE ACTIVITY IN RHEUMATOID ARTHRITIS?

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 23.2-24
Author(s):  
V. Molander ◽  
H. Bower ◽  
J. Askling
Keyword(s):  
Rheumatoid Arthritis ◽  
Logistic Regression ◽  
Venous Thromboembolism ◽  
Disease Activity ◽  
Das28 Score ◽  
Logistic Regression Models ◽  
Highly Active ◽  
Increased Risk ◽  
Das28 Remission ◽  
One Year

Background:Patients with rheumatoid arthritis (RA) are at increased risk for venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE) (1). Several established risk factors of VTE, such as age, immobilization and comorbid conditions, occur more often patients with RA (2). In addition, inflammation may in itself also increase VTE risk by upregulating procoagolatory factors and causing endothelial damage (3). Recent reports indicate an increased risk of VTE in RA patients treated with JAK-inhibitors (4), pointing to the need to better understand how inflammation measured as clinical RA disease activity influences VTE risk.Objectives:To investigate the relationship between clinical RA disease activity and incidence of VTE.Methods:Patients with RA were identified from the Swedish Rheumatology Quality Register (SRQ) between July 1st2006 and December 31st2017. Clinical rheumatology data for these patients were obtained from the visits recorded in SRQ, and linked to national registers capturing data on VTE events and comorbid conditions. For each such rheumatologist visit, we defined a one-year period after the visit and determined whether a VTE event had occurred within this period or not. A visit followed by a VTE event was categorized as a case, all other visits were used as controls. Each patient could contribute to several visits. The DAS28 score registered at the visit was stratified into remission (0-2.5) vs. low (2.6-3.1), moderate (3.2-5.1) and high (>5.1) disease activity. Logistic regression with robust cluster standard errors was used to estimate the association between the DAS28 score and VTE.Results:We identified 46,311 patients with RA who contributed data from 320,094 visits. Among these, 2,257 visits (0.7% of all visits) in 1345 unique individuals were followed by a VTE within the one-year window. Of these, 1391 were DVT events and 866 were PE events. Figure 1 displays the absolute probabilities of a VTE in this one-year window, and odds ratios for VTE by each DAS28 category, using DAS28 remission as reference. The one-year risk of a VTE increased from 0.5% in patients in DAS28 remission, to 1.1% in patients with DAS28 high disease activity (DAS28 above 5.1). The age- and sex-adjusted odds ratio for a VTE event in highly active RA compared to RA in remission was 2.12 (95% CI 1.80-2.47). A different analysis, in which each patient could only contribute to one visit, yielded similar results.Figure 1.Odds ratios (OR) comparing the odds of VTE for DAS28 activity categories versus remission. Grey estimates are from unadjusted logistic regression models, black estimates are from logistic regression models adjusted for age and sex. Absolute one-year risk of VTE are estimated from unadjusted models.Conclusion:This study demonstrates a strong association between clinical RA inflammatory activity as measured through DAS28 and risk of VTE. Among patients with high disease activity one in a hundred will develop a VTE within the coming year. These findings highlight the need for proper VTE risk assessment in patients with active RA, and confirm that patients with highly active RA, such as those recruited to trials for treatment with new drugs, are already at particularly elevated risk of VTE.References:[1]Holmqvist et al. Risk of venous thromboembolism in patients with rheumatoid arthritis and association with disease duration and hospitalization. JAMA. 2012;308(13):1350-6.[2]Cushman M. Epidemiology and risk factors for venous thrombosis. Semin Hematol. 2007;44(2):62-9.[3]Xu J et al. Inflammation, innate immunity and blood coagulation. Hamostaseologie. 2010;30(1):5-6, 8-9.[4]FDA. Safety trial finds risk of blood clots in the lungs and death with higher dose of tofacitinib (Xeljanz, Xeljanz XR) in rheumatoid arthritis patients; FDA to investigate. 2019.Acknowledgments:Many thanks to all patients and rheumatologists persistently filling out the SRQ.Disclosure of Interests:Viktor Molander: None declared, Hannah Bower: None declared, Johan Askling Grant/research support from: JA acts or has acted as PI for agreements between Karolinska Institutet and the following entities, mainly in the context of the ARTIS national safety monitoring programme of immunomodulators in rheumatology: Abbvie, BMS, Eli Lilly, Merck, MSD, Pfizer, Roche, Samsung Bioepis, Sanofi, and UCB Pharma

scholarly journals Potential Source Areas for Atmospheric Lead Reaching Ny-Ålesund from 2010 to 2018

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 388
Author(s):  
Andrea Bazzano ◽  
Stefano Bertinetti ◽  
Francisco Ardini ◽  
David Cappelletti ◽  
Marco Grotti
Keyword(s):  
North American ◽  
Enrichment Factors ◽  
Atmospheric Particulate Matter ◽  
Back Trajectory ◽  
Pb Isotope ◽  
Back Trajectories ◽  
Source Areas ◽  
The North ◽  
Central Asian ◽  
Pb Concentration

Lead content, enrichment factors, and isotopic composition (208Pb/206Pb and 207Pb/206Pb) measured in atmospheric particulate matter (PM10) samples collected for nine years at Ny-Ålesund (Svalbard islands, Norwegian Arctic) during spring and summer are presented and discussed. The possible source areas (PSA) for particulate inferred from Pb isotope ratio values were compared to cluster analysis of back-trajectories. Results show that anthropogenic Pb dominates over natural crustal Pb, with a recurring higher influence in spring, compared to summer. Crustal Pb accounted for 5–16% of the measured Pb concentration. Anthropogenic Pb was affected by (i) a Central Asian PSA with Pb isotope signature compatible with ores smelted in the Rudny Altai region, at the Russian and Kazakhstan border, which accounted for 85% of the anthropogenic Pb concentration, and (ii) a weaker North American PSA, contributing for the remaining 15%. Central Asian PSA exerted an influence on 71–86% of spring samples, without any significant interannual variation. On the contrary, 59–87% of summer samples were influenced by the North American PSA, with higher contributions during 2015 and 2018. Back-trajectory analysis agreed on the seasonal difference in PSA and highlighted a possible increased influence for North American air masses during summer 2010 and 2018, but not for summer 2015.

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