Utility of 222Rn as a passive tracer of subglacial distributed system drainage
Utility of 222Rn as a passive tracer of subglacial distributed system drainage
复制标题
222Rn 作为冰下分布式系统排水被动示踪剂的用途
DOI：
10.1016/j.epsl.2016.12.039
复制
发表时间：
2017
影响因子：
5.3
通讯作者：
Linhoff B
中科院分区：
文献类型：
--
作者：
Linhoff B
格陵兰冰盖（GrIS）下的水流已被证明包括缓慢低效（分布式）和快速高效（渠道化）的排水系统，以响应融水通过冰臼和地表湖泊排水输送到床。渠化和分布式排水系统之间的这种分区很难量化，但它在大量融水化学和冰川速度，从而冰下侵蚀中起着重要作用。氡-222是通过226 Ra的衰变不断产生的，它在与岩石和沉积物相互作用的融水中积累。因此，222 Rn浓度升高应表明融水已流过分布式排水系统网络。在2011年和2012年的春季和夏季，我们在GrIS（莱弗里特冰川，格陵兰西南部）的一个大出口冰川的冰前河进行了每小时222 Rn测量。氡-222的活度在融化季节的早期最高（10-15 dpm L−1），在大范围的地表融化开始后下降2-5倍（3-5 dpm L−1）。使用a222 Rn质量平衡模型，我们估计，平均而言，超过90%的河流222 Rn来自分布式系统融水。分布系统222 Rn通量变化的昼夜，每周和季节的时间尺度上的最高通量一般发生在下降的分支的过程线和渠化排水系统的扩张。使用基于实验室的分布式系统222 Rn的估计，分布式系统的水通量一般在1-5%之间的总冰前河流流量的两个季节。这项研究提供了一个很有前途的新方法，在冰川流域的过程线分离和估计的时间和规模的分布式系统在冰盖边缘排出通量。
Water flow beneath the Greenland Ice Sheet (GrIS) has been shown to include slow-inefficient (distributed) and fast-efficient (channelized) drainage systems, in response to meltwater delivery to the bed via both moulins and surface lake drainage. This partitioning between channelized and distributed drainage systems is difficult to quantify yet it plays an important role in bulk meltwater chemistry and glacial velocity, and thus subglacial erosion. Radon-222, which is continuously produced via the decay of226Ra, accumulates in meltwater that has interacted with rock and sediment. Hence, elevated concentrations of222Rn should be indicative of meltwater that has flowed through a distributed drainage system network. In the spring and summer of 2011 and 2012, we made hourly222Rn measurements in the proglacial river of a large outlet glacier of the GrIS (Leverett Glacier, SW Greenland). Radon-222 activities were highest in the early melt season (10–15 dpm L−1), decreasing by a factor of 2–5 (3–5 dpm L−1) following the onset of widespread surface melt. Using a222Rn mass balance model, we estimate that, on average, greater than 90% of the river222Rn was sourced from distributed system meltwater. The distributed system222Rn flux varied on diurnal, weekly, and seasonal time scales with highest fluxes generally occurring on the falling limb of the hydrograph and during expansion of the channelized drainage system. Using laboratory based estimates of distributed system222Rn, the distributed system water flux generally ranged between 1–5% of the total proglacial river discharge for both seasons. This study provides a promising new method for hydrograph separation in glacial watersheds and for estimating the timing and magnitude of distributed system fluxes expelled at ice sheet margins.
登录
查看更多内容
影响因子：
5.8
作者：
Cowton, T.;Nienow, P.;Mair, D.
通讯作者：
Mair, D.
影响因子：
18.3
作者：
Chandler, D. M.;Wadham, J. L.;Hubbard, A.
通讯作者：
Hubbard, A.
冰川融水研究中的天然放射性同位素
DOI：
--
发表时间：
2011
期刊：
影响因子：
--
作者：
A. Kies;A. Nawrot;Z. Tosheva;J. Jania
通讯作者：
J. Jania
影响因子：
18.3
作者：
Bartholomew, Ian;Nienow, Peter;Sole, Andrew
通讯作者：
Sole, Andrew
冰河管道形成机制及其对冰下补给的影响
影响因子：
4
作者：
J. Gulley;D. Benn;E. Screaton;Jonathan B. Martin
通讯作者：
Jonathan B. Martin