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The influence of probe spacing and probe bias in a double Langmuir probe setup
Get PDFMulti-needle Langmuir probes are mounted on satellites and sounding rockets for high-frequency characterization of plasma in the ionosphere. Mounted on a spacecraft, the recorded probe current often differs from expected results. In this paper, we perform a numerical study using a particle in cell model to see how the spacing between the individual probes used in a multi-needle setup influences the measured current. We also study how the applied probe bias voltage can contribute to deviations. In our study, we use realistic electron temperatures and electron densities for the relevant part of the ionosphere. However, the results should be generally applicable and valid for other space environments as well as for laboratory Langmuir probe applications. From our study, we can see that when the distance is short, less than two Debye lengths, the current is highly affected, and we can see deviations of more than 60% compared to a single probe setup.publishedVersio
Effekt av rakettoppskyting i Ny-Ålesund i 2018 og 2019
Get PDFThe report summarizes the results from additional snow sampling and regular monitoring activities in connection to the rocket launch in Ny-Ålesund 7 Dec 2018, 26 Nov 2019 and 10 Dec 2019 to document possible impacts on environment and on the monitoring activities in Ny-Ålesund. An enhanced deposition of aluminium (Al) and iron (Fe) on the local environment due to the rocket launch is observed.Rapporten oppsummerer resultatene fra ekstra analyser av snøprøver samt pågående overvåkingsaktiviteter i forbindelse med rakettoppskytingen i Ny-Ålesund 7. desember 2018, 26. november 2019 og 10. desember 2019 for å dokumentere mulige påvirkninger av rakettoppskyting på miljøet og overvåkingsaktivitetene i Ny-Ålesund. Det observeres en økt avsetning av Al og Fe i Ny-Ålesund-området som skyldes utslipp fra rakettoppskytingen.publishedVersio
Concentrations and geographical patterns of persistent organic pollutants (POPs) in meat from semi-domesticated reindeer (Rangifer tarandus tarandus L.) in Norway
Get PDFThe study aimed at investigating the concentrations and geographical patterns of 11 polychlorinated biphenyls (PCBs) and 15 organochlorine pesticides (OCPs) in reindeer muscle samples (n = 100) collected from 10 grazing districts in Norway, 2009. Concentrations were examined for patterns related to geographical region as well as age and sex of animals. Concentrations measured for PCBs and OCPs in reindeer meat samples were generally low. Geographical patterns were revealed and districts with previous mining activities, military trenches, or those that were in the vicinity of the Russian border exhibited slightly elevated concentrations compared to other districts. Calves (10 months) exhibited higher concentrations than young (1.5 year) and old animals (>2 years) adjusted for sex, whereas males exhibited higher concentrations than females, adjusted for age. All PCB congeners inter-correlated strongly with each other, whereas oxy-chlordane and heptachlor epoxide were the strongest inter-correlated OCP compounds. Concentrations of PCBs and OCPs in reindeer meat were all considerably lower than the maximum levels set for those contaminants in foodstuffs for safe human consumption by the European Commission. Thus, reindeer meat is not likely to be a substantial contributor to the human body burden of persistent organic pollutants.publishedVersio
Introducing a nested multimedia fate and transport model for organic contaminants (NEM)
No full textSome organic contaminants, including the persistent organic pollutants (POPs), have achieved global distribution through long range atmospheric transport (LRAT). Regulatory efforts, monitoring programs and modelling studies address the LRAT of POPs on national, continental (e.g. Europe) and/or global scales. Whereas national and continental-scale models require estimates of the input of globally dispersed chemicals from outside of the model domain, existing global-scale models either have relatively coarse spatial resolution or are so computationally demanding that it limits their usefulness. Here we introduce the Nested Exposure Model (NEM), which is a multimedia fate and transport model that is global in scale yet can achieve high spatial resolution of a user-defined target region without huge computational demands. Evaluating NEM by comparing model predictions for PCB-153 in air with measurements at nine long-term monitoring sites of the European Monitoring and Evaluation Programme (EMEP) reveals that nested simulations at a resolution of 1° × 1° yield results within a factor of 1.5 of observations at sites in northern Europe. At this resolution, the model attributes more than 90% of the atmospheric burden within any of the grid cells containing an EMEP site to advective atmospheric transport from elsewhere. Deteriorating model performance with decreasing resolution (15° × 15°, 5° × 5° and 1° × 1°), manifested by overestimation of concentrations across most of northern Europe by more than a factor of 3, illustrates the effect of numerical diffusion. Finally, we apply the model to demonstrate how the choice of spatial resolution affect predictions of atmospheric deposition to the Baltic Sea. While we envisage that NEM may be used for a wide range of applications in the future, further evaluation will be required to delineate the boundaries of applicability towards chemicals with divergent fate properties as well as in environmental media other than air.publishedVersio
The Community Inversion Framework v1.0: a unified system for atmospheric inversion studies
Get PDFAtmospheric inversion approaches are expected to play a critical role in future observation-based monitoring systems for surface fluxes of greenhouse gases (GHGs), pollutants and other trace gases. In the past decade, the research community has developed various inversion software, mainly using variational or ensemble Bayesian optimization methods, with various assumptions on uncertainty structures and prior information and with various atmospheric chemistry–transport models. Each of them can assimilate some or all of the available observation streams for its domain area of interest: flask samples, in situ measurements or satellite observations. Although referenced in peer-reviewed publications and usually accessible across the research community, most systems are not at the level of transparency, flexibility and accessibility needed to provide the scientific community and policy makers with a comprehensive and robust view of the uncertainties associated with the inverse estimation of GHG and reactive species fluxes. Furthermore, their development, usually carried out by individual research institutes, may in the future not keep pace with the increasing scientific needs and technical possibilities. We present here the Community Inversion Framework (CIF) to help rationalize development efforts and leverage the strengths of individual inversion systems into a comprehensive framework. The CIF is primarily a programming protocol to allow various inversion bricks to be exchanged among researchers. In practice, the ensemble of bricks makes a flexible, transparent and open-source Python-based tool to estimate the fluxes of various GHGs and reactive species both at the global and regional scales. It will allow for running different atmospheric transport models, different observation streams and different data assimilation approaches. This adaptability will allow for a comprehensive assessment of uncertainty in a fully consistent framework. We present here the main structure and functionalities of the system, and we demonstrate how it operates in a simple academic case.publishedVersio
A European aerosol phenomenology - 7: High-time resolution chemical characteristics of submicron particulate matter across Europe
Get PDFSimilarities and differences in the submicron atmospheric aerosol chemical composition are analyzed from a unique set of measurements performed at 21 sites across Europe for at least one year. These sites are located between 35 and 62°N and 10° W – 26°E, and represent various types of settings (remote, coastal, rural, industrial, urban). Measurements were all carried out on-line with a 30-min time resolution using mass spectroscopy based instruments known as Aerosol Chemical Speciation Monitors (ACSM) and Aerosol Mass Spectrometers (AMS) and following common measurement guidelines. Data regarding organics, sulfate, nitrate and ammonium concentrations, as well as the sum of them called non-refractory submicron aerosol mass concentration ([NR-PM1]) are discussed. NR-PM1 concentrations generally increase from remote to urban sites. They are mostly larger in the mid-latitude band than in southern and northern Europe. On average, organics account for the major part (36–64%) of NR-PM1 followed by sulfate (12–44%) and nitrate (6–35%). The annual mean chemical composition of NR-PM1 at rural (or regional background) sites and urban background sites are very similar. Considering rural and regional background sites only, nitrate contribution is higher and sulfate contribution is lower in mid-latitude Europe compared to northern and southern Europe. Large seasonal variations in concentrations (μg/m³) of one or more components of NR-PM1 can be observed at all sites, as well as in the chemical composition of NR-PM1 (%) at most sites. Significant diel cycles in the contribution to [NR-PM1] of organics, sulfate, and nitrate can be observed at a majority of sites both in winter and summer. Early morning minima in organics in concomitance with maxima in nitrate are common features at regional and urban background sites. Daily variations are much smaller at a number of coastal and rural sites. Looking at NR-PM1 chemical composition as a function of NR-PM1 mass concentration reveals that although organics account for the major fraction of NR-PM1 at all concentration levels at most sites, nitrate contribution generally increases with NR-PM1 mass concentration and predominates when NR-PM1 mass concentrations exceed 40 μg/m³ at half of the sites.publishedVersio
Vurdering av luftkvalitet i omgivelsene til Hydro Sunndal aluminiumsmelter
Get PDFOn behalf of Aluminiumindustriens Miljøsekretariat (AMS), NILU – Norwegian Institute for Air Research has conducted a sampling campaign in the surroundings of the Hydro Sunndal aluminium smelter in order to update the knowledge on air quality around the smelter today. Samples were taken in summer 2019 and analysed for PM2.5, PM10, metals (Pb, Cd, Cr, Ni, As, Al, V, Ga, Sb, Bi), particle-bound PAHs, SO2, particle-bound and gaseous fluorides. As a consequence of reduced emissions compared to earlier measurements, the ambient concentrations of PM10, Cr, Pb, BaP (for PAHs), SO2 and fluorides were strongly reduced. All measured compounds had concentrations below limit values and recommended guideline values.På oppdrag fra Aluminiumindustriens Miljøsekretariat (AMS), har NILU – Norsk institutt for luftforskning gjennomført en prøvetakingskampanje i omgivelsene til aluminiumssmelteverket Hydro Sunndal for å oppdatere kunnskapen om luftkvalitet rundt smelteverket i dag. Prøvene ble tatt sommeren 2019 og analysert for PM2.5, PM10, metaller (Pb, Cd, Cr, Ni, As, Al, V, Ga, Sb, Bi), partikkelbundne PAHer, SO2, partikkelbundne og gassformige fluorider. Som en konsekvens av reduserte utslipp sammenlignet med tidligere målinger, ble konsentrasjonene av PM10, Cr, Pb, BaP (for PAH), SO2 og fluorider sterkt redusert. Alle målte forbindelser hadde konsentrasjoner under grenseverdier og anbefalte retningslinjer.publishedVersio
Assessment of emissions to air from the Wisting oil field in the Barents Sea
Get PDFNILU har vurdert miljøkonsekvensene av utslipp til luft fra fremtidig utbygging og drift av Wisting-feltet i Barentshavet. Utslipp av CO2, CH4, N2O og NMVOC er vurdert utfra bidrag til strålingspådriv/global oppvarming. Kraftforsyning fra land med sjøkabel vil sterkt redusere utslippene av CO2. Klimaeffekten av utslipp til luft fra produksjonen vil bli liten. Bidraget fra Wisting til eutrofiering og forsuring gjennom avsetning av NOx og SOx forventes å være lite og knapt målbart. Likeledes vil bidraget fra Wisting til ozonproduksjon være minimalt og knapt målbart. Klimaeffekten av BC-utslipp (Black Carbon) fra installasjonene på Wisting vil bli liten. Samtidig gir utslipp av BC i Arktis større effekt pr. utslippsenhet enn utslipp lenger sør. Det bør derfor være et mål å optimalisere faklingen fra Wisting slik at utslipp av BC blir redusert til et absolutt minimum.The environmental impact of future emissions from activities at the Wisting oil field in the Barents Sea has been investigated. Emissions of av CO2, CH4, N2O og NMVOC will be low and the climate effect from these emissions will be minor. Emissions of NOx and SOx will be low and their contribution to eutrophication and acidification will be minor. Also the formation of ozone due to NOx emissions will be low. The climate effect due to emissions of black carbon (BC) will be low. However, emissions of BC in the Arctic will have greater impact per unit emitted than emissions further south. Flaring at Wisting should be optimized to reduce emissions of BC to a minimum.publishedVersio
Time trends of perfluoroalkyl substances in blood in 30-year old Norwegian men and women in the period 1986–2007
Get PDFBiomonitoring studies are helpful tools and can increase our knowledge on time trends in human blood concentrations of PFASs: how they relate to emission trends and the potential prenatal exposure for future generations. In this study, serum was sampled in cross-sections of men and women who were 30 years old in each of the years 1986, 1994, 2001, and 2007 in Northern Norway and analyzed for 23 PFASs. Differences in serum concentrations across sampling years were investigated graphically and with significance testing and compared with those observed in our previous longitudinal study using repeated individual measurements in older men in the same years. The results demonstrate overall increasing blood burdens of PFASs in men and women in reproductively active ages during 1986–2001 and decreases until 2007. However, longer chained PFASs were still increasing in 2007 indicating divergent time trends between the different PFASs, underlining the importance of continued biomonitoring. Comparisons between 30-year-old men and older men within the same population demonstrated variation in time trends in the exact same years, underlining that biomonitoring studies must regard historic exposures and birth cohort effects.publishedVersio
Large seasonal and interannual variations of biogenic sulfur compounds in the Arctic atmosphere (Svalbard; 78.9° N, 11.9° E)
Get PDFSeasonal to interannual variations in the concentrations of sulfur aerosols (< 2.5 µm in diameter; non sea-salt sulfate: NSS-SO2−4; anthropogenic sulfate: Anth-SO2−4; biogenic sulfate: Bio-SO2−4; methanesulfonic acid: MSA) in the Arctic atmosphere were investigated using measurements of the chemical composition of aerosols collected at Ny-Ålesund, Svalbard (78.9∘ N, 11.9∘ E) from 2015 to 2019. In all measurement years the concentration of NSS-SO2−4 was highest during the pre-bloom period and rapidly decreased towards summer. During the pre-bloom period we found a strong correlation between NSS-SO2−4 (sum of Anth-SO2−4 and Bio-SO2−4) and Anth-SO2−4. This was because more than 50 % of the NSS-SO2−4 measured during this period was Anth-SO2−4, which originated in northern Europe and was subsequently transported to the Arctic in Arctic haze. Unexpected increases in the concentration of Bio-SO2−4 aerosols (an oxidation product of dimethylsulfide: DMS) were occasionally found during the pre-bloom period. These probably originated in regions to the south (the North Atlantic Ocean and the Norwegian Sea) rather than in ocean areas in the proximity of Ny-Ålesund. Another oxidation product of DMS is MSA, and the ratio of MSA to Bio-SO2−4 is extensively used to estimate the total amount of DMS-derived aerosol particles in remote marine environments. The concentration of MSA during the pre-bloom period remained low, primarily because of the greater loss of MSA relative to Bio-SO2−4 and the suppression of condensation of gaseous MSA onto particles already present in air masses being transported northwards from distant ocean source regions (existing particles). In addition, the low light intensity during the pre-bloom period resulted in a low concentration of photochemically activated oxidant species including OH radicals and BrO; these conditions favored the oxidation pathway of DMS to Bio-SO2−4 rather than to MSA, which acted to lower the MSA concentration at Ny-Ålesund. The concentration of MSA peaked in May or June and was positively correlated with phytoplankton biomass in the Greenland and Barents seas around Svalbard. As a result, the mean ratio of MSA to the DMS-derived aerosols was low (0.09 ± 0.07) in the pre-bloom period but high (0.32 ± 0.15) in the bloom and post-bloom periods. There was large interannual variability in the ratio of MSA to Bio-SO2−4 (i.e., 0.24 ± 0.11 in 2017, 0.40 ± 0.14 in 2018, and 0.36 ± 0.14 in 2019) during the bloom and post-bloom periods. This was probably associated with changes in the chemical properties of existing particles, biological activities surrounding the observation site, and air mass transport patterns. Our results indicate that MSA is not a conservative tracer for predicting DMS-derived particles, and the contribution of MSA to the growth of newly formed particles may be much larger during the bloom and post-bloom periods than during the pre-bloom period.publishedVersio