Silvia Becagli - Academia.edu (original) (raw)
Papers by Silvia Becagli
Journal of Electroanalytical Chemistry, 1999
Electrohydrodimerization (EHD) of fumarodinitrile (R) from dilute aqueous solutions of the strong... more Electrohydrodimerization (EHD) of fumarodinitrile (R) from dilute aqueous solutions of the strong surfactant Triton X-100 takes place both on liquid gallium and on mercury, via a rate-determining homogeneous radical -radical coupling step. However, the potential range over which EHD takes place is much narrower on gallium than on mercury. This behaviour is due to the fact that adsorbed water molecules act as proton donors towards the radical anion R − , giving rise to the neutral radical RH , which is immediately reduced to the saturated monomer RH 2 . Therefore, EHD requires the complete displacement of water molecules from the adsorbed state by Triton X-100; this is more difficult on the hydrophilic gallium than on the hydrophobic mercury. This also explains why, even though fumarodinitrile is much more strongly adsorbed on gallium than on mercury, no appreciable radical-radical coupling takes place in the adsorbed state on gallium. Acrylonitrile is reduced to the saturated monomer on gallium under the same experimental conditions in which it undergoes EHD on mercury. This is also due to the high hydrophilicity of gallium.
Climate Dynamics, 2004
Surface mass balance (SMB) distribution and its temporal and spatial variability is an essential ... more Surface mass balance (SMB) distribution and its temporal and spatial variability is an essential input parameter in mass balance studies. Different methods were used, compared and integrated (stake farms, ice cores, snow radar, surface morphology, remote sensing) at eight sites along a transect from Terra Nova Bay (TNB) to Dome C (DC) (East Antarctica), to provide detailed information on the SMB. Spatial variability measurements show that the measured maximum snow accumulation (SA) in a 15 km area is well correlated to firn temperature. Wind-driven sublimation processes, controlled by the surface slope in the wind direction, have a huge impact (up to 85% of snow precipitation) on SMB and are significant in terms of past, present and future SMB evaluations. The snow redistribution process is local and has a strong impact on the annual variability of accumulation. The spatial variability of SMB at the kilometre scale is one order of magnitude higher than its temporal variability (20-30%) at the centennial time scale. This high spatial variability is due to wind-driven sublimation. Compared with our SMB calculations, previous compilations generally over-estimate SMB, up to 65% in some areas.
Surface mass balance distribution and its temporal and spatial variability is an input parameter ... more Surface mass balance distribution and its temporal and spatial variability is an input parameter in mass balance studies. It also has important implications for palaeoclimatic series from ice cores. Different methods were adopted, compared and integrated (stake farm, core analysis, snow radar, surface morphology, remote sensing) at eight sites along a transept from Terra Nova Bay to Dome C (East Antarctica). Cores were linked by snow radar and GPS surveys to provide detailed information on spatial variability in surface mass balance. Thirty-nine cores were dated by identifying tritium/β marker levels (1965-66) and nssSO4 2- spikes of Tambora and Unknown volcanic events (1816 - 1810) in order to provide information on temporal variability. Spatial variability measurements show that maximum snow accumulation is strictly correlated to firn temperature and that it is homogenous at macro-scales (hundreds of km2). Wind-driven sublimation processes, controlled by surface slope in the wind ...
The Holocene volcanic record, as recorded in the Antarctic ice sheet, has been reconstructed by u... more The Holocene volcanic record, as recorded in the Antarctic ice sheet, has been reconstructed by using the sulfate record of the EDC96 ice core, drilled in the framework of the European Project for Ice Coring in Antarctica (EPICA). The number of volcanic signatures recovered in the EDC96 ice core during the Holocene is 95, with a mean value of 7.9
Journal of Electroanalytical Chemistry, 1999
Electrohydrodimerization (EHD) of fumarodinitrile (R) from dilute aqueous solutions of the strong... more Electrohydrodimerization (EHD) of fumarodinitrile (R) from dilute aqueous solutions of the strong surfactant Triton X-100 takes place both on liquid gallium and on mercury, via a rate-determining homogeneous radical -radical coupling step. However, the potential range over which EHD takes place is much narrower on gallium than on mercury. This behaviour is due to the fact that adsorbed water molecules act as proton donors towards the radical anion R − , giving rise to the neutral radical RH , which is immediately reduced to the saturated monomer RH 2 . Therefore, EHD requires the complete displacement of water molecules from the adsorbed state by Triton X-100; this is more difficult on the hydrophilic gallium than on the hydrophobic mercury. This also explains why, even though fumarodinitrile is much more strongly adsorbed on gallium than on mercury, no appreciable radical-radical coupling takes place in the adsorbed state on gallium. Acrylonitrile is reduced to the saturated monomer on gallium under the same experimental conditions in which it undergoes EHD on mercury. This is also due to the high hydrophilicity of gallium.
Climate Dynamics, 2004
Surface mass balance (SMB) distribution and its temporal and spatial variability is an essential ... more Surface mass balance (SMB) distribution and its temporal and spatial variability is an essential input parameter in mass balance studies. Different methods were used, compared and integrated (stake farms, ice cores, snow radar, surface morphology, remote sensing) at eight sites along a transect from Terra Nova Bay (TNB) to Dome C (DC) (East Antarctica), to provide detailed information on the SMB. Spatial variability measurements show that the measured maximum snow accumulation (SA) in a 15 km area is well correlated to firn temperature. Wind-driven sublimation processes, controlled by the surface slope in the wind direction, have a huge impact (up to 85% of snow precipitation) on SMB and are significant in terms of past, present and future SMB evaluations. The snow redistribution process is local and has a strong impact on the annual variability of accumulation. The spatial variability of SMB at the kilometre scale is one order of magnitude higher than its temporal variability (20-30%) at the centennial time scale. This high spatial variability is due to wind-driven sublimation. Compared with our SMB calculations, previous compilations generally over-estimate SMB, up to 65% in some areas.
Surface mass balance distribution and its temporal and spatial variability is an input parameter ... more Surface mass balance distribution and its temporal and spatial variability is an input parameter in mass balance studies. It also has important implications for palaeoclimatic series from ice cores. Different methods were adopted, compared and integrated (stake farm, core analysis, snow radar, surface morphology, remote sensing) at eight sites along a transept from Terra Nova Bay to Dome C (East Antarctica). Cores were linked by snow radar and GPS surveys to provide detailed information on spatial variability in surface mass balance. Thirty-nine cores were dated by identifying tritium/β marker levels (1965-66) and nssSO4 2- spikes of Tambora and Unknown volcanic events (1816 - 1810) in order to provide information on temporal variability. Spatial variability measurements show that maximum snow accumulation is strictly correlated to firn temperature and that it is homogenous at macro-scales (hundreds of km2). Wind-driven sublimation processes, controlled by surface slope in the wind ...
The Holocene volcanic record, as recorded in the Antarctic ice sheet, has been reconstructed by u... more The Holocene volcanic record, as recorded in the Antarctic ice sheet, has been reconstructed by using the sulfate record of the EDC96 ice core, drilled in the framework of the European Project for Ice Coring in Antarctica (EPICA). The number of volcanic signatures recovered in the EDC96 ice core during the Holocene is 95, with a mean value of 7.9