115 research outputs found
An 800-year high-resolution black carbon ice core record from Lomonosovfonna, Svalbard
Produced by the incomplete combustion of fossil fuel and biomass, black
carbon (BC) contributes to Arctic warming by reducing snow albedo and thus
triggering a snow-albedo feedback leading to increased snowmelt. Therefore,
it is of high importance to assess past BC emissions to better understand and
constrain their role. However, only a few long-term BC records are available
from the Arctic, mainly originating from Greenland ice cores. Here, we
present the first long-term and high-resolution refractory black carbon (rBC)
record from Svalbard, derived from the analysis of two ice cores drilled at
the Lomonosovfonna ice field in 2009 (LF-09) and 2011 (LF-11) and covering
800 years of atmospheric emissions. Our results show that rBC concentrations
strongly increased from 1860 on due to anthropogenic emissions and reached
two maxima, at the end of the 19th century and in the middle of the 20th
century. No increase in rBC concentrations during the last decades was
observed, which is corroborated by atmospheric measurements elsewhere in the
Arctic but contradicts a previous study from another ice core from Svalbard.
While melting may affect BC concentrations during periods of high
temperatures, rBC concentrations remain well preserved prior to the 20th
century due to lower temperatures inducing little melt. Therefore, the
preindustrial rBC record (before 1800), along with ammonium (NH4+),
formate (HCOO−) and specific organic markers (vanillic acid, VA, and
p-hydroxybenzoic acid, p-HBA), was used as a proxy for
biomass burning. Despite numerous single events, no long-term trend was
observed over the time period 1222–1800 for rBC and NH4+. In
contrast, formate, VA, and p-HBA experience multi-decadal peaks reflecting
periods of enhanced biomass burning. Most of the background variations and
single peak events are corroborated by other ice core records from Greenland
and Siberia. We suggest that the paleofire record from the LF ice core
primarily reflects biomass burning episodes from northern Eurasia, induced by
decadal-scale climatic variations.</p
Revue bibliographique quantitative sur l'utilisation des hormones anabolisantes à action stéroïdienne chez les ruminants en production de viande. Il. Principaux modes d'action
International audienc
Comparaison de différentes méthodes d'interprétation de la prédiction de l'eau corporelle par la méthode de dilution de l'eau lourde : application chez le chevreau mâle
International audienc
Effet de l'association estradiol-17β et acétate de trenbolone sur la concentration plasmatique de certains métabolites et hormones chez le chevreau avant un repas
International audienc
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