Ionic variability in snow and firn along an Antarctic transect

• Published in: Pesquisas em Geociências
• Main Authors: LINDAU, Filipe G. L., SIMÕES, Jefferson C., MARQUES, Magdalena M., HAMMES, Daiane F., DA SILVA, Daniel B., CASASSA, Gino, SNEED, Sharon, INTRONE, Douglas
• Format: Article in Journal/Newspaper
• Language: Portuguese
• Published: Instituto de Geociências /Universidade Federal do Rio Grande do Sul 2016
• Subjects: Major ions; snow and firn cores; Antarctica; Íons majoritários; testemunhos de neve e firn; Antártica; Antarctic; Patriot Hills; Polo; South Pole; Antarc*; Sea ice; South pole
• Online Access: https://seer.ufrgs.br/index.php/PesquisasemGeociencias/article/view/78218

In order to interpret the ionic variability in snow and firn from Patriot Hills (80º18’S, 81º21’W) to the South Pole, we determined the major ions concentrations and isotopic ratios of five snow and firn cores (less than 46 m deep) for the 200 first fractions, collected during the 2004–2005 Chilean-Brazilian traverse. After cleaning the samples (in a cold room) and melting it (in a class 100 clean room), we determined the Na+ , K+ , Mg2+, Ca2+, MS- (CH3 SO3 - ), Cl- , NO3 - and SO4 2- concentrations by ion chromatography, with detection limits from 0.3 to 1.8 µg L-1 depending on the ion. For deuterium/hydrogen isotopic ratio (δD) the precision is 0.5‰. We dated the samples with annual precision and ±2 years accuracy, by counting the Na+ , nssSO4 2- (non-sea-salt sulfate) and δD annual layers. Then we obtained, for the five snow and firn cores sites, the mean net snow accumulation rates. They show a negative correlation (r >0.4, module) with increasing elevation and sea distance, yet responding to local superficial features and katabatic winds occurrence. The snow and firn cores reveal alterations in the sea salt aerosols Na+ /Cl- ratios, but the aerosols produced during sea ice formation appear only on the nearest sites of the coast. The NO3 - , as the MS- record, indicates the occurrence of post-depositional processes connected to volcanic events and photochemical reactions, which intensity increases on glaze surfaces. Com o objetivo de interpretar a variabilidade no conteúdo iônico da neve e do firn entre Patriot Hills (80º18’S, 81º21’W) e o Polo Sul Geográfico, foram determinadas as concentrações dos íons majoritários e as razões isotópicas das 200 primeiras frações de cinco testemunhos de neve e firn (com profundidades de até 46 m), durante a travessia chileno-brasileira ocorrida no verão de 2004–2005. Após as amostras serem limpas (em câmara fria) e derretidas (em sala limpa classe 100), os íons Na+ , K+ , Mg2+, Ca2+, MS- (CH3 SO3 - ), Cl- , NO3 - e SO4 2- foram analisados por cromatografia iônica, com ...