Fant 9759 publikasjoner. Viser side 309 av 391:
2009
2021
2011
SF6 as a greenhouse gas: An assessment of Norwegian global sources and the global warming potential. NILU OR
1993
Sheath formation time for spherical Langmuir probes
The formation time of the surrounding sheath of Langmuir probes in an ionospheric plasma has been studied to better understand the constraints this puts on the sampling frequency of a probe. A fully kinetic three-dimensional particle-in-cell model is used to simulate the temporal effects in the electron saturation region as the sheath forms. The stability of the probe current and the stability of the ion and electron density in the vicinity of the probe have been used to evaluate when the sheath was formed. Simulated results were compared with theoretical models and are in good agreement with the theoretical results. This shows that theoretical models can be used as guidance to estimate the formation time and to determine the sampling rate for a swept bias Langmuir system. Our results also show that the formation time is less affected by the plasma temperature and bias voltage as we move into the thick sheath regime, and will instead be determined by the plasma density. The presented results also show that applying a step function to the probe could be used to characterise ions species composition, or to estimate the ion density.
Cambridge University Press
2023
Per- and polyfluoroalkyl substances (PFAS) have gained significant global attention due to their extensive industrial use and harmful effects on various organisms. Among these, perfluoroalkyl acids (PFAAs) are well-studied, but their diverse precursors remain challenging to monitor. The Total Oxidizable Precursor (TOP) assay offers a powerful approach to converting these precursors into detectable PFAAs. In this study, the TOP assay was applied to samples from the East Asian-Australian Flyway, a critical migratory route for millions of shorebirds. Samples included shellfish from China's coastal mudflats, key stopover sites for these birds, and blood and liver samples from shorebirds overwintering in Australia. The results showed a substantial increase in perfluorocarboxylic acids (PFCAs) across all sample types following the TOP assay, with the most significant increases in shorebird livers (Sum PFCAs increased by 18,156 %). Intriguingly, the assay also revealed unexpected increases in perfluorosulfonic acids (PFSAs), suggesting the presence of unidentified precursors. These findings highlight the need for further research into these unknown precursors, their sources, and their ecological impacts on shorebirds, other wildlife, and potential human exposure. This study also provides crucial insights into the TOP assay’s strengths and limitations in studying PFAS precursor dynamics in biological matrices.
Elsevier
2025
SHIPMATE - Ship traffic particulate matter emissions. Final project report. NILU report
I SHIPMATE-prosjektet er det gjennomført målinger av en rekke forurensningskomponenter og aerosoler på Mt. Zeppelin observatoriet i løpet av 2014 og 2015. Målet for prosjektet var 1) å kartlegge hvor mye skipstrafikken bidrar til de observerte svevestøv-nivåene og 2) identifisere tidsrom i eksisterende tidsserier som i betydelig grad er påvirket av lokale utslipp fra skipstrafikken. Det siste er viktig for at tidsserien skal kunne benyttes for å studere regionale trender for ulike forurensningskomponenter i atmosfæren. Basert på en vurdering av gunstig vindretning mot målestasjonen med samtidige skipsanløp til Ny-Ålesund, er det identifisert alt åtte 3-dagers episoder hvor utslipp fra skipsfart påvirker datagrunnlaget. I disse episodene bidro utslipp fra skipstrafikken med ca. 50% av konsentrasjoner av følgende tungmetaller: Cu, Ni, Zn og Cd. Disse resultatene understøttes av en berikelsesfaktoranalyse av prøvene. Forekomst av episoder hvor skipstrafikk påvirker målingene ved målestasjonen på Mt. Zeppelin forekommer derimot sjeldent.
2016
2017
Shipping emissions in the port of Oslo: inventory, mitigation strategies and future scenario. NILU F
2014
2011
2013
2006
2008
2008
2013
2023
2023
2017
Siberian Arctic black carbon: gas flaring and wildfire impact
As explained in the latest Arctic Monitoring and Assessment Programme (AMAP) report released in early 2021, the Arctic has warmed 3 times more quickly than the planet as a whole, as well as faster than previously thought. The Siberian Arctic is of great interest mainly because observations are sparse or largely lacking. A research aerosol station has been developed on Bely Island (Kara Sea) in western Siberia. Measurements of equivalent black carbon (EBC) concentrations were carried out at the “Island Bely” station continuously from August 2019 to November 2020. The source origin of the measured EBC and the main contributing sources were assessed using atmospheric transport modeling coupled with the most updated emission inventories for anthropogenic and biomass burning sources of BC.
The obtained climatology for BC during the period of measurements showed an apparent seasonal variation with the highest concentrations between December and April (60 ± 92 ng m−3) and the lowest between June and September (18 ± 72 ng m−3), typical of the Arctic haze seasonality reported elsewhere. When air masses arrived at the station through the biggest oil and gas extraction regions of Kazakhstan, Volga-Ural, Komi, Nenets and western Siberia, BC contribution from gas flaring dominated over domestic, industrial and traffic sectors, ranging from 47 % to 68 %, with a maximum contribution in January. When air was transported from Europe during the cold season, emissions from transportation were more important. Accordingly, shipping emissions increased due to the touristic cruise activities and the ice retreat in summertime. Biomass burning (BB) played the biggest role between April and October, contributing 81 % at maximum in July. Long-range transport of BB aerosols appeared to induce large variability to the absorption Ångström exponent (AAE) with values > 1.0 (excluding outliers). As regards the continental contribution to surface BC at the Island Bely station, Russian emissions dominated during the whole year, while European and Asian ones contributed up to 20 % in the cold period. Quantification of several pollution episodes showed an increasing trend in surface concentrations and frequency during the cold period as the station is directly in the Siberian gateway of the highest anthropogenic pollution sources to the Russian Arctic.
2022