Direct observations of aluminosilicate weathering in the hyporheic zone of an Antarctic Dry Valley stream

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• 作者：Maurice ; Patricia A. ; McKnight ; Diane M. ; Leff ; Laura ; Fulghum ; Julia E. ; Gooseff ; Michael
• 刊名：Geochimica et Cosmochimica Acta
• 出版年：2002
• 出版时间：April 15, 2002
• 年：2002
• 卷：66
• 期：8
• 页码：1335-1347
• 全文大小：1.80 M

文摘

This study focused on chemical weathering and bacterial ecology in the hyporheic zone of Green Creek, a McMurdo Dry Valley (Antarctica) stream. An in situ microcosm approach was used to observe dissolution features on the basal-plane surface of muscovite mica. Four mica chips were buried in December 1999 and dug up 39 d later. Atomic force microscopy (AFM) of the basal-plane surfaces revealed small, anhedral n=center border=0 SRC=/images/glyphs/BQ1.GIF>10-Å-deep etch pits covering n=center border=0 SRC=/images/glyphs/BQ1.GIF>4 % of the surfaces, from which an approximate basal-plane dissolution rate of 8.3 × 10^−18 mol muscovite cm^−2 s^−1 was calculated (on the basis of the geometric surface area) for the study period. This is an integrated initial dissolution rate on a fresh surface exposed for a relatively brief period over the austral summer and should not be compared directly to other long-term field rates. The observation of weathering features on mica agrees with previous stream- and watershed-scale studies in the Dry Valleys, which have demonstrated that weathering occurs where liquid water is present, despite the cold temperatures.