Physicochemical properties of bottom ice from Dome Fuji, inland East Antarctica
Physicochemical properties of bottom ice from Dome Fuji, inland East Antarctica
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南极洲东部内陆圆顶富士底部冰的物理化学特性
DOI：
10.1002/2015jf003777
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
H
中科院分区：
文献类型：
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作者：
Ohno;H.;Iizuka;Y.;Hori;A.;Miyamoto;A.;Hirabayashi;M.;Miyake;T.;Kuramoto;T.;Fujita;S.;Segawa;T.;Uemura;R.;Sakurai;T.;Suzuki;T.;and Motoyama;H
南极洲内陆最深的冰预计将保存最古老的冰记录，并可能含有微生物。然而，人们对冰盖最深处的物理化学条件知之甚少。本研究调查的物理化学性质的圆顶富士内陆冰芯，这是直接位于未冻基岩上方的底部（3000-3035米）。空气水合物的普遍存在和冰的水同位素组成与上部主冰芯相当，表明底部冰是大气的。然而，离子浓度在最大深度（约低于3033米）处显示出异常下降。在相同的深度范围内，显微镜调查显示，空气水合物和微夹杂物（水溶性杂质）发生了相当大的重新定位，这表明所观察到的离子浓度降低是由于夹杂物分离到冰颗粒边界以及随后通过液态水脉排放化学物质。离子数据的主成分分析支持流星冰假说，表明底部冰在所有深度都具有相似的原始化学成分。化学数据的统计分析表明，附着在水合物或粉尘（不溶于水）上的水溶性杂质、冰溶性化学物质（如氯）和固体颗粒受这种化学置换现象的影响较小。同样值得注意的是，在底部的冰中，限制冰栖微生物营养的杂质化学物质主要集中在冰水合物界面上，在那里，氧气，另一种对好氧微生物至关重要的物质，也得到了富集。
The deepest ice in inland Antarctica is expected to preserve the oldest ice records and to potentially contain microorganisms. However, little is known about the physicochemical conditions in the deepest part of ice sheets. This study investigates the physicochemical properties of the bottom section (3000–3035 m) of the Dome Fuji inland ice core, which is located immediately above unfrozen bedrock. The ubiquitous presence of air hydrates and the water isotope composition of ice comparable to the upper main ice core show that the bottom ice is meteoric. However, ion concentrations exhibit abnormal drops at the greatest depths (approximately below 3033 m). In the same depth range, microscopic investigations reveal that considerable relocation of air hydrates and microinclusions (water‐soluble impurities) occurs, suggesting that the observed reduction in ion concentration results from the segregation of inclusions to ice grain boundaries and the subsequent discharge of chemicals through liquid‐water veins. Principal component analysis of ion data supports the meteoric‐ice hypothesis, suggesting that the bottom ice had similar original chemistry through all depths. Statistical analyses of chemical data suggest that the water‐soluble impurities attached to hydrates or dust (water‐insoluble), the ice‐soluble chemical species (such as chlorine), and solid particles are less affected by this chemical displacement phenomenon. It is also noteworthy that in the bottom ice, impurity chemicals, which are limiting nutrients for ice‐dwelling microorganisms, are concentrated largely to ice‐hydrate interfaces, where oxygen, another vital matter for aerobic microorganisms, is also enriched.