Found 10000 publications. Showing page 174 of 400:
HBr emissions from volcanoes lead rapidly to the formation of BrO within volcanic plumes and have an impact on tropospheric chemistry, at least at the local and regional scales. The motivation of this paper is to prepare a framework for further 3D modelling of volcanic halogen emissions in order to determine their fate within the volcanic plume and then in the atmosphere at the regional and global scales. The main aim is to evaluate the ability of the model to produce a realistic partitioning of bromine species within a grid box size typical of MOCAGE (Model Of atmospheric Chemistry At larGE scale) 3D (0.5∘ × 0.5∘). This work is based on a 1D single-column configuration of the global chemistry-transport model MOCAGE that has low enough computational cost to allow us to perform a large set of sensitivity simulations. This paper uses the emissions from the Mount Etna eruption on 10 May 2008. Several reactions are added to MOCAGE to represent the volcanic plume halogen chemistry. A simple plume parameterisation is also implemented and tested. The use of this parameterisation tends to only slightly limit the efficiency of BrO net production. Both simulations with and without the parameterisation give results for the partitioning of the bromine species, of ozone depletion and of the ratio that are consistent with previous studies.
A series of test experiments were performed to evaluate the sensitivity of the results to the composition of the emissions (primary sulfate aerosols, Br radical and NO) and to the effective radius assumed for the volcanic sulfate aerosols. Simulations show that the plume chemistry is sensitive to all these parameters. We also find that the maximum altitude of the eruption changes the BrO production, which is linked to the vertical variability of the concentrations of oxidants in the background air. These sensitivity tests display changes in the bromine chemistry cycles that are generally at least as important as the plume parameterisation. Overall, the version of the MOCAGE chemistry developed for this study is suitable to produce the expected halogen chemistry in volcanic plumes during daytime and night-time.
2023
Halogenated organic contaminants (HOCs) and mercury in dead or dying seabirds on Bjørnøya (Svalbard). TA-2222/2007
2007
2007
2012
Halogenerte organiske miljøgifter og kvikksølv i norsk ferskvannsfisk, 1995-1999. NIVA-rapport, 4402-01
2001
NILU og Akvaplan-niva har et felles overvåkingsprosjekt rundt Hammerfest LNG på Melkøya. I perioden 2025 – 2028 skal overvåkingen omfatte bly (Pb), kvikksølv (Hg) og PAH i nedbør, vegetasjon, jord, ferskvann, ferskvannsfisk og ferskvannssediment, samt kvikksølv i luft. For de fleste komponenter og prøvemedier er verdiene lave.
NILU
2025
2010
2020
2019
2019
Abstract. Establishing interlaboratory compatibility among measurements of stable isotope ratios of atmospheric methane (δ13C-CH4 and δD-CH4) is challenging. Significant offsets are common because laboratories have different ties to the VPDB or SMOW-SLAP scales. Umezawa et al. (2018) surveyed numerous comparison efforts for CH4 isotope measurements conducted from 2003 to 2017 and found scale offsets of up to 0.5 ‰ for δ13C-CH4 and 13 ‰ for δD-CH4 between laboratories. This exceeds the World Meteorological Organisation Global Atmospheric Watch (WMO-GAW) network compatibility targets of 0.02 ‰ and 1 ‰ considerably. We employ a method to establish scale offsets between laboratories using their reported CH4 isotope measurements on atmospheric samples. Our study includes data from eight laboratories with experience in high-precision isotope ratio mass spectrometry (IRMS) measurements for atmospheric CH4. The analysis relies exclusively on routine atmospheric measurements conducted by these laboratories at high-latitude stations in the Northern and Southern Hemispheres, where we assume each measurement represents sufficiently well-mixed air at the latitude for direct comparison. We use two methodologies for interlaboratory comparisons: (I) assessing differences between time-adjacent observation data and (II) smoothing the observed data using polynomial and harmonic functions before comparison. The results of both methods are consistent, and with a few exceptions, the overall average offsets between laboratories align well with those reported by Umezawa et al. (2018). This indicates that interlaboratory offsets remain robust over multi-year periods. The evaluation of routine measurements allows us to calculate the interlaboratory offsets from hundreds, in some cases thousands of measurements. Therefore, the uncertainty in the mean interlaboratory offset is not limited by the analytical error of a single analysis but by real atmospheric variability between the sampling dates and stations. Using the same method, we assess this uncertainty by investigating measurements from four high-latitude sites analysed by the INSTAAR laboratory. After applying the derived interlaboratory offsets, we present a harmonised time series for δ13C-CH4 and δD-CH4 at high northern and southern latitudes, covering the period from 1988 to 2023.
2025
2011
2011
Hazard and exposure assessment of do-it-yourself products forimpregnation
A large number of do-it-yourself impregnation products are marketed to Danish consumers. The products are typically used for re-impregnation of consumer products (e.g. footware and outdoor clothing) immediately after the products have been purchased or when the water and/or dirt-repellent effect begins to diminish.
The Danish Environmental Protection Agency has chosen to make a survey of the market, where 110 do-it-yourself impregnation products were identified within ten different application categories. Out of these products, 14 were included in initial chemical content analyzes, as well as hazard and exposure analyzes. The main components in the majority of the products were saturated hydrocarbons, but some of the products also contained oxygen-containing solvents (e.g. alcohols, ethers, esters or ketones). The potential hazard of 12 of the 14 selected impregnation spray products was performed by measuring acute respiratory toxicity. Of the 12 products tested, 10 inhibited the function of the lung surfactant and may therefore potentially be harmful by inhalation.
On the basis of this study, it could not be demonstrated that the products with PFAS resulted in an inhibition of the lung surfactant at lower doses as compared to products without PFAS; in fact, the lowest inhibitory doses were seen for impregnating agents based on siloxanes/silicones. The results show that the hazardous properties of an impregnation product cannot be determined solely on the basis of the ingredients, and it is therefore necessary to examine the ability of the individual products to inhibit the lung surfactant in connection with a hazard assessment.
Danish Environmental Protection Agency
2023