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Gabrieli J.,CNR Institute for the Dynamics of Environmental Processes | Barbante C.,CNR Institute for the Dynamics of Environmental Processes | Barbante C.,University of Venice | Barbante C.,Centro B Segre
Rendiconti Lincei | Year: 2014

The evaluation of the impact of anthropogenic activities on mountain areas is an important task, because they represent the last remaining natural and pristine environments in highly industrialized continental regions. The deposition of ubiquitous, persistent and toxic organic pollutants in high-altitude sites can potentially affect the alpine ecosystem, which is often characterized by unique plant and animal communities which are precious in terms of ecological value as well as being fragile and easily spoiled. Records from Alpine ice cores have demonstrated to be among the best tools in paleoenvironmental studies to reconstruct past emissions of heavy metals and persistent organic pollutants. From the comparison of trace species records in the snow and ice with the emission inventories compiled in recent years it is also possible to reconstruct the past trends in the emission of these compounds. This knowledge enables a better environmental management and a more effective planning of the human activities in the light of a new sustainable development and could represent the base of a wide and motivated participation to the creation of the future generations. Here, we summarize the results of the geochemical analysis of the Colle Gnifetti firn/ice core, in the Monte Rosa group (NW European Alps). © 2014 Accademia Nazionale dei Lincei.

Vallelonga P.,Copenhagen University | Vallelonga P.,University of Venice | Barbante C.,University of Venice | Barbante C.,Centro B Segre | And 6 more authors.
Climate of the Past | Year: 2013

Atmospheric fluxes of iron (Fe) over the past 200 kyr are reported for the coastal Antarctic Talos Dome ice core, based on acid leachable Fe concentrations. Fluxes of Fe to Talos Dome were consistently greater than those at Dome C, with the greatest difference observed during interglacial climates. We observe different Fe flux trends at Dome C and Talos Dome during the deglaciation and early Holocene, attributed to a combination of deglacial activation of dust sources local to Talos Dome and the reorganization of atmospheric transport pathways with the retreat of the Ross Sea ice shelf. This supports similar findings based on dust particle sizes and fluxes and Rare Earth Element fluxes. We show that Ca and Fe should not be used as quantitative proxies for mineral dust, as they all demonstrate different deglacial trends at Talos Dome and Dome C. Considering that a 20 ppmv decrease in atmospheric CO2 at the coldest part of the last glacial maximum occurs contemporaneously with the period of greatest Fe and dust flux to Antarctica, we confirm that the maximum contribution of aeolian dust deposition to Southern Ocean sequestration of atmospheric CO2 is approximately 20 ppmv. © Author(s) 2013.

Gabrielli P.,Ohio State University | Hardy D.R.,University of Massachusetts Amherst | Kehrwald N.,University of Venice | Davis M.,Ohio State University | And 6 more authors.
Quaternary Science Reviews | Year: 2014

Ice fields on Kilimanjaro (5895m a.s.l., Tanzania) are retreating and 85% of the ice cover has been lost since 1912. The degree to which this recession is exceptional during the Holocene is uncertain, as age control of the entire ice stratigraphy exists only for the very shallow and very bottom ice of the Northern Ice Field. This empirical evidence suggests that the Kilimanjaro ice cover may be a persistent Holocene feature, while a model based on maximum possible extent and a constant shrinkage rate of the summit glaciers suggests a cyclic decay time on the order of one to two centuries. Today the mass balance of these ice fields is negative and no persistent ice accumulation zones are observed over multiannual scales. The expanding deglaciated area within the Kilimanjaro caldera should act as an increasingly larger and productive source of volcanic-origin aeolian dust that is quickly deposited onto the surface of the adjacent ice fields, particularly in the seasonal absence of caldera snow cover. Variations in the local dust influx may directly influence albedo and the energy balance of these ice fields. Investigating the characteristics of insoluble material entrapped in the ice remnants of Kilimanjaro can thus provide insights into the extent of ice and/or continuity of the summit snow cover through time. Here we report the trace element composition linked to the insoluble particles entrapped in Holocene Kilimanjaro ice in the context of the current understanding of the past ice accumulation processes (including solid precipitations and ablation) contributing to build the horizontal caldera ice fields. For this purpose we analysed an ice core drilled to bedrock from the Northern Ice Field thought to span the late Holocene (2200 BC-1950 AD). The ultra low trace element concentrations recorded in this Kilimanjaro core are consistent with a generally low volcanic dust source availability (i.e. limited exposure of the deglaciated area in the caldera) and fairly continuous ice accumulation during the late Holocene. In contrast, the maximum concentrations for most of the trace elements recorded in the surface ice section suggest that the current lack of ice accumulation on the Kilimanjaro ice fields is unusual over the last ~4ka. © 2014.

Zennaro P.,CNR Institute of Neuroscience | Zennaro P.,University of Venice | Kehrwald N.,University of Venice | Marlon J.,Yale University | And 10 more authors.
Geophysical Research Letters | Year: 2015

The timing of initiation of human impacts on the global climate system is actively debated. Anthropogenic effects on the global climate system are evident since the Industrial Revolution, but humans may have altered biomass burning, and hence the climate system, for millennia. We use the specific biomarker levoglucosan to produce the first high-temporal resolution hemispheric reconstruction of Holocene fire emissions inferred from ice core analyses. Levoglucosan recorded in the Greenland North Greenland Eemian ice core significantly increases since the last glacial, resulting in a maximum around ∼2.5 ka and then decreasing until the present. Here we demonstrate that global climate drivers fail to explain late Holocene biomass burning variations and that the levoglucosan maximum centered on ∼2.5 ka may be due to anthropogenic land clearance. © 2015. The Authors.

Spolaor A.,University of Siena | Spolaor A.,University of Venice | Vallelonga P.,Niels Bohr Institute | Gabrieli J.,University of Venice | And 8 more authors.
Analytical and Bioanalytical Chemistry | Year: 2013

Iodine and bromine species participate in key atmospheric reactions including the formation of cloud condensation nuclei and ozone depletion. We present a novel method coupling a high-performance liquid chromatography with ion chromatography and inductively coupled plasma mass spectrometry, which allows the determination of iodine (I) and bromine (Br) species (IO 3 -, I-, Br-, BrO 3 - ) at the picogram-per-gram levels presents in Antarctic ice. Chromatographic separation was achieved using an IONPAC® AS16 Analytical Column with NaOH as eluent. Detection limits for I and Br species were 5 to 9 pg g-1 with an uncertainty of less than 2.5% for all considered species. Inorganic iodine and bromine species have been determined in Antarctic ice core samples, with concentrations close to the detection limits for iodine species, and approximately 150 pg g-1 for Br-. Although iodate (IO 3 - ) is the most abundant iodine species in the atmosphere, only the much rarer iodide (I-) species was present in Antarctic Holocene ice. Bromine was found to be present in Antarctic ice as Br-. © 2012 Springer-Verlag.

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