Microbial processes in the weathering crust aquifer of a temperate glacier
Microbial processes in the weathering crust aquifer of a temperate glacier
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DOI：
10.5194/tc-12-3653-2018
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发表时间：
2018-11-26
期刊：
影响因子：
5.2
通讯作者：
Stone, William C.
中科院分区：
文献类型：
--
作者：
Christner, Brent C.;Lavender, Heather F.;Stone, William C.
冰川消融带吸收的入射太阳辐射产生了一个浅栖息含水层和季节性冰封微生物栖息地。在2014年和2015年的融化季节，钻孔调查被用来检查的物理，地球化学和微生物学特性的近地表冰和含水层的温带Matanuska冰川（阿拉斯加中南部）。根据温度、太阳强迫和冰的光学特性，短波辐射的消散促进了内部熔融和风化壳的形成，最大深度约为2米。在风化壳上打钻孔，就可以通过多孔的冰层获取水分。水有低离子浓度（4-12亩S cm-1），有氧（12毫克O-2 L-1），含有200至8300个细胞mL（-1），并窝藏增长的人口估计在原位代时间为11至14天。在融化季节，冰层上部2 m处经历了至少3%的表面光合有效辐射通量，并且含水量高达10%。非原位代谢实验和含水层样品中存在的光养类群（蓝藻、金色和绿色藻类）支持风化壳生态系统中生物地球化学反应的光合维持。融水持续时间类似于7.5个月，再加上增长估计意味着生物量每年可能增加4个数量级。我们的研究结果提供了深入了解季节性动态如何影响近地表冰的可居住性和微生物过程中的一部分冰川生物群落准备扩大的程度，随着全球温度和消融季节持续时间的增加。
Incident solar radiation absorbed within the ablation zone of glaciers generates a shallow perched aquifer and seasonal icebound microbial habitat. During the melt seasons of 2014 and 2015, borehole investigations were used to examine the physical, geochemical, and microbiological properties in the near-surface ice and aquifer of the temperate Matanuska Glacier (south-central Alaska). Based on temperature, solar forcing, and ice optical properties, the dissipation of shortwave radiation promoted internal melting and the formation of a weathering crust with a maximum depth of similar to 2 m. Boreholes into the weathering crust provided access to water percolating through the porous ice. The water had low ion concentrations (4-12 mu S cm 1), was aerobic (12 mg O-2 L-1), contained 200 to 8300 cells mL(-1), and harbored growing populations with estimated in situ generation times of 11 to 14 days. During the melt season, the upper 2 m of ice experienced at least 3% of the surface photosynthetically active radiation flux and possessed a fractional water content as high as 10 %. Photosynthetic subsistence of biogeochemical reactions in the weathering crust ecosystem was supported by ex situ metabolic experiments and the presence of phototrophic taxa (cyanobacteria, golden and green algae) in the aquifer samples. Meltwater durations of similar to 7.5 months coupled with the growth estimates imply biomass may increase by 4 orders of magnitude each year. Our results provide insight into how seasonal dynamics affect habitability of near-surface ice and microbial processes in a portion of the glacial biome poised to expand in extent with increasing global temperature and ablation season duration.