Examinando por Autor "Lambert, Fabrice"

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    Black carbon and other light-absorbing impurities in snow in the Chilean Andes
    (Nature Publishing Group, 2019-12) Rowe, Penny M.; Cordero, Raul R.; Warren, Stephen G.; Stewart, Emily; Doherty, Sarah J.; Pankow, Alec; Schrempf, Michael; Casassa, Gino; Carrasco, Jorge; Pizarro, Jaime; MacDonell, Shelley; Damiani, Alessandro; Lambert, Fabrice; Rondanelli, Roberto; Huneeus, Nicolas; Fernandoy, Francisco; Neshyba, Steven
    Vertical profiles of black carbon (BC) and other light-absorbing impurities were measured in seasonal snow and permanent snowfields in the Chilean Andes during Austral winters 2015 and 2016, at 22 sites between latitudes 18°S and 41°S. The samples were analyzed for spectrally-resolved visible light absorption. For surface snow, the average mass mixing ratio of BC was 15 ng/g in northern Chile (18–33°S), 28 ng/g near Santiago (a major city near latitude 33°S, where urban pollution plays a significant role), and 13 ng/g in southern Chile (33–41°S). The regional average vertically-integrated loading of BC was 207 µg/m 2 in the north, 780 µg/m 2 near Santiago, and 2500 µg/m 2 in the south, where the snow season was longer and the snow was deeper. For samples collected at locations where there had been no new snowfall for a week or more, the BC concentration in surface snow was high (~10–100 ng/g) and the sub-surface snow was comparatively clean, indicating the dominance of dry deposition of BC. Mean albedo reductions due to light-absorbing impurities were 0.0150, 0.0160, and 0.0077 for snow grain radii of 100 µm for northern Chile, the region near Santiago, and southern Chile; respective mean radiative forcings for the winter months were 2.8, 1.4, and 0.6 W/m 2 . In northern Chile, our measurements indicate that light-absorption by impurities in snow was dominated by dust rather than BC. © 2019, The Author(s).
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    Elemental and Mineralogical Composition of the Western Andean Snow (18°S–41°S)
    (Nature Publishing Group, 2019-12) Alfonso, Juan A.; Cordero, Raul R.; Rowe, Penny M.; Neshyba, Steven; Casassa, Gino; Carrasco, Jorge; MacDonell, Shelley; Lambert, Fabrice; Pizarro, Jaime; Fernandoy, Francisco; Feron, Sarah; Damiani, Alessandro; Llanillo, Pedro; Sepulveda, Edgardo; Jorquera, Jose; Garcia, Belkis; Carrera, Juan M.; Oyola, Pedro; Kang, Choong-Min
    The snowpack is an important source of water for many Andean communities. Because of its importance, elemental and mineralogical composition analysis of the Andean snow is a worthwhile effort. In this study, we conducted a chemical composition analysis (major and trace elements, mineralogy, and chemical enrichment) of surface snow sampled at 21 sites across a transect of about 2,500 km in the Chilean Andes (18–41°S). Our results enabled us to identify five depositional environments: (i) sites 1–3 (in the Atacama Desert, 18–26°S) with relatively high concentrations of metals, high abundance of quartz and low presence of arsenates, (ii) sites 4–8 (in northern Chile, 29–32°S) with relatively high abundance of quartz and low presence of metals and arsenates, (iii) sites 9–12 (in central Chile, 33–35°S) with anthropogenic enrichment of metals, relatively high values of quartz and low abundance of arsenates, (iv) sites 13–14 (also in central Chile, 35–37°S) with relatively high values of quartz and low presence of metals and arsenates, and v) sites 15–21 (in southern Chile, 37–41°S) with relatively high abundance of arsenates and low presence of metals and quartz. We found significant anthropogenic enrichment at sites close to Santiago (a major city of 6 million inhabitants) and in the Atacama Desert (that hosts several major copper mines). © 2019, The Author(s).