Water tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem
Water tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem
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南极洲泰勒谷的水道和永久冻土：寒冷沙漠生态系统中广泛而浅层的地下水连通性
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发表时间：
2011
期刊：
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通讯作者：
W. Lyons
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作者：
J. Levy;A. Fountain;M. Gooseff;K. Welch;W. Lyons
水迹是土壤湿度高的区域，在极地环境中，水沿着冰面向下流动。我们目前的物理，水文和地球化学证据收集在泰勒谷，麦克默多干谷，南极洲，这表明，以前未开发的水轨道是一个重要组成部分，这个寒冷的沙漠土地系统，并构成一个神秘的水文系统的主要流动路径。地质、地球化学和水文分析表明，水迹是由积雪融化、水迹下方冰床处孔隙冰融化和冬季冻结期间形成的埋藏隔离冰融化的渗透相结合而产生的。水迹富含来自沉积物化学风化和土壤盐溶解的溶质。这些水流入冰湖，如霍尔湖，导致浅层地下水溶液和冰川水的相互作用，增加了地球化学剖面的复杂性。大约四个数量级少的水输送到霍尔湖由任何给定的水轨道比从流的地表径流输送;然而，溶质输送到霍尔湖由水轨道等于或可能超过从流传递的溶质的质量，使水轨道显着的地球化学途径。此外，溶质的运输是两个数量级更快的水轨道比邻近的干燥或潮湿的土壤，使水轨道“盐高速公路”在南极寒冷的沙漠。因此，水迹代表了一种新的地质路径，在南极干谷，寒冷的沙漠，土壤生态系统中分配水，能量和营养物质，提供山坡尺度的水文和地球化学连通性。
Water tracks are zones of high soil moisture that route water downslope over the ice table in polar environments. We present physical, hydrological, and geochemical evidence collected in Taylor Valley, McMurdo Dry Valleys, Antarctica, which suggests that previously unexplored water tracks are a significant component of this cold desert land system and constitute the major flow path in a cryptic hydrological system. Geological, geochemical, and hydrological analyses show that the water tracks are generated by a combination of infiltration from melting snowpacks, melting of pore ice at the ice table beneath the water tracks, and melting of buried segregation ice formed during winter freezing. The water tracks are enriched in solutes derived from chemical weathering of sediments as well as from dissolution of soil salts. The water tracks empty into ice-covered lakes, such as Lake Hoare, resulting in the interfingering of shallow groundwater solutions and glacier-derived stream water, adding complexity to the geochemical profile. Approximately four orders of magnitude less water is delivered to Lake Hoare by any given water track than is delivered by surface runoff from stream flow; however, the solute delivery to Lake Hoare by water tracks equals or may exceed the mass of solutes delivered from stream flow, making water tracks significant geochemical pathways. Additionally, solute transport is two orders of magnitude faster in water tracks than in adjacent dry or damp soil, making water tracks “salt superhighways” in the Antarctic cold desert. Accordingly, water tracks represent a new geological pathway that distributes water, energy, and nutrients in Antarctic Dry Valley, cold desert, soil ecosystems, providing hydrological and geochemical connectivity at the hillslope scale.