Fant 10273 publikasjoner. Viser side 104 av 411:
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1999
Distribution of polychlorinated biphenyls (PCBs) in snow samples in northern Norway. Organohalogen compounds, 39
1998
2009
Diurnal cycle of iodine, bromine, and mercury concentrations in Svalbard surface snow
Sunlit snow is highly photochemically active and plays a key role in the exchange of gas phase species between the cryosphere and the atmosphere. Here, we investigate the behaviour of two selected species in surface snow: mercury (Hg) and iodine (I). Hg can deposit year-round and accumulate in the snowpack. However, photo-induced re-emission of gas phase Hg from the surface has been widely reported. Iodine is active in atmospheric new particle formation, especially in the marine boundary layer, and in the destruction of atmospheric ozone. It can also undergo photochemical re-emission. Although previous studies indicate possible post-depositional processes, little is known about the diurnal behaviour of these two species and their interaction in surface snow. The mechanisms are still poorly constrained, and no field experiments have been performed in different seasons to investigate the magnitude of re-emission processes Three sampling campaigns conducted at an hourly resolution for 3 d each were carried out near Ny-Ålesund (Svalbard) to study the behaviour of mercury and iodine in surface snow under different sunlight and environmental conditions (24 h darkness, 24 h sunlight and day–night cycles). Our results indicate a different behaviour of mercury and iodine in surface snow during the different campaigns. The day–night experiments demonstrate the existence of a diurnal cycle in surface snow for Hg and iodine, indicating that these species are indeed influenced by the daily solar radiation cycle. Differently, bromine did not show any diurnal cycle. The diurnal cycle also disappeared for Hg and iodine during the 24 h sunlight period and during 24 h darkness experiments supporting the idea of the occurrence (absence) of a continuous recycling or exchange at the snow–air interface. These results demonstrate that this surface snow recycling is seasonally dependent, through sunlight. They also highlight the non-negligible role that snowpack emissions have on ambient air concentrations and potentially on iodine-induced atmospheric nucleation processes.
2019
2010
Divergent impacts of climate interventions on China’s north-south water divide
Abstract Solar radiation modification-based climate interventions may cause uneven regional hydrological changes while mitigating warming. Here, we investigate the effects of climate interventions on China’s North Drought-South Flood pattern using the Norwegian Earth System Model supplemented by volcanic data. Our results indicate that equatorial stratospheric aerosol injection could mitigate the north-south water divide by reducing inter-hemispheric and equator-to-North-pole temperature gradients, thereby modifying atmospheric circulation and the East Asian monsoon to increase precipitation and surface runoff in northern China while reducing them in the south, compared to the high emissions scenario. This mechanism is supported by observed precipitation changes following the Mount Pinatubo volcanic eruption. In contrast, marine cloud brightening may intensify southern flood risks, while cirrus cloud thinning and moderate emissions reduction might exacerbate northern droughts. Our findings reveal distinct regional hydroclimatic impacts of different climate interventions, highlighting potential synergies and trade-offs between their global intervention efficacy and regional water security.
2025
2012
2010
2016
Environmental contaminants are found throughout Arctic marine ecosystems, and their presence in seabirds has been
associated with toxicological responses. However, there are few studies of genotoxicity in Arctic avian wildlife. The purpose of
the present study was to quantify deoxyribonucleic acid (DNA) damage in lymphocytes of selected seabird species and to
examine whether accumulation of organohalogen contaminants (SOHCs) affects DNA damage. Blood was sampled from
common eider (Somateria mollissima), black guillemot (Cepphus grylle), black-legged kittiwake (Rissa tridactyla), glaucous gull
(Larus hyperboreus), arctic skua (Stercorarius parasiticus), and great skua (Stercorarius skua) in Kongsfjorden, Svalbard (Norway).
Contaminant concentrations found in the 6 species differed, presumably because of foraging ecology and biomagnification.
Despite large differences in contaminant concentrations, ranging from SOHCs 3.3 ng/g wet weight in the common eider to
SOHCs 895 ng/g wet weight in the great skua, there was no strong difference among the species in baseline DNA damage or
sensitivity to a genotoxic stressor (hydrogen peroxide). Baseline levels of DNA damage were low, with median values ranging
from 1.7% in the common eider to 8.6% in the great skua. There were no associations between DNA damage and contaminants
in the investigated species, suggesting that contaminant concentrations in Kongsfjorden are too low to evoke genotoxic effects,
or possibly that lymphocytes are resistant to strand breakage. Clearly, genotoxicity is a topic for future studies of Arctic seabirds
Arctic; Seabirds; Genotoxicity; Comet Assay; Persistent organic pollutants; Perfluoroalkyl substances
2018
2018