A stable isotopic investigation of a polar desert hydrologic system, McMurdo Dry Valleys, Antarctica
A stable isotopic investigation of a polar desert hydrologic system, McMurdo Dry Valleys, Antarctica
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DOI：
10.1657/1523-0430(2006)038
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发表时间：
2006-02-01
影响因子：
2
通讯作者：
Dowling, C
中科院分区：
文献类型：
--
作者：
Gooseff, MN;Lyons, WB;Dowling, C
南极洲沿海麦克默多干谷的水文系统由积雪、冰川融化、水流和封闭盆地、冰雪覆盖的湖泊中的滞留所定义。在1993-1996年和1999-2000年至2002-2003年的南方夏季，新鲜的雪，雪坑，冰川冰，溪水，和湖泊沃茨的稳定同位素氘（D）和180，以解决融水的来源和各种水文水库之间的相互作用在干旱河谷。该数据集提供了一个调查的天然水同位素丰度分布在泰勒谷，从麦克默多声音内陆延伸20公里的明确的干谷水文系统。泰勒谷的三个主要湖泊彼此不相连，它们的水位由冰川融水流入和常年水文、冰盖升华维持。在山谷尺度上，随着与麦克默多湾（更远的内陆）距离的增加，三角洲D中的冰川冰、雪、溪流和湖泊沃茨变得更加枯竭。冰川堆积区的积雪是异质的，可能是不同风暴源（大陆与沿海）的结果，一般来说，雪坑，新鲜的雪样本和冰川冰比溪流沃茨更枯竭。在湖盆内，与湖泊沃茨相比，冰川冰源沃茨中的8D和O-18分别减少了111%.和20%.。这些结果表明，在流分馏在山谷规模的重要性。流内富集发生在从冰源到湖泊的运输过程中，通过直接蒸发分馏从通道和潜流交换同位素富集的沃茨在近流次表层。此外，研究结果表明，湖泊沃茨直接反映了他们的冰川冰源，尽管在流传输分馏。湖泊剖面的年际比较表明，湖泊沃茨的同位素组成和流量在一个赛季的直接影响。
The hydrologic system of the coastal McMurdo Dry Valleys, Antarctica, is defined by snow accumulation, glacier melt, stream flow, and retention in closed-basin, ice-covered lakes. During the austral summers from 1993-1996 and 1999-2000 to 2002-2003, fresh snow, snow pits, glacier ice, stream water, and lake waters were sampled for the stable isotopes deuterium (D) and 180 in order to resolve sources of meltwater and the interactions among the various hydrologic reservoirs in the dry valleys. This data set provides a survey of the distribution of natural water isotope abundances within the well-defined dry valley hydrologic system in Taylor Valley, which extends 20 km inland from McMurdo Sound. The three major Taylor Valley lakes are not connected to one another and their levels are maintained by glacial meltwater inflow and perennial hydrologically, ice-cover sublimation. At the valley scale, glacial ice, snow, stream, and lake waters become more depleted in delta D with increasing distance from McMurdo Sound (further inland). Snow pack in glacial accumulation zones is heterogeneous, likely a result of varying storm sources (continental versus coastal), and, in general, snow pits, fresh snow samples, and glacier ice are more depleted than stream waters. Within the lake basins, glacial ice source waters are depleted by as much as 111 parts per thousand 8D and 20 parts per thousand delta O-18 compared to lake waters. These results demonstrate the importance of in-stream fractionation at the valley scale. In-stream enrichment occurs through direct evaporation fractionation from the channel and hyporheic exchange with isotopically enriched waters in the near-stream subsurface during transport from the glacial source to lake. Furthermore, the results show that lake waters directly reflect their glacial ice sources, despite fractionation during stream transport. Inter-annual comparisons of lake profiles suggest that lake waters are directly influenced by the isotopic composition and amount of stream flow during a season.