Flowpath and retention of snowmelt in an ice-covered arctic lake: Flowpath and retention of snowmelt
Flowpath and retention of snowmelt in an ice-covered arctic lake: Flowpath and retention of snowmelt
复制标题
冰雪覆盖的北极湖泊中融雪的流动路径和滞留：融雪的流动路径和滞留
DOI：
10.1002/lno.10549
复制
发表时间：
2017
影响因子：
4.5
通讯作者：
Sadro, Steven
中科院分区：
文献类型：
--
作者：
Cortés, Alicia;MacIntyre, Sally;Sadro, Steven
流入冰雪覆盖的湖泊的融雪水平扩散和垂直混合的程度影响了景观中溶质的保留。为了量化这些运输过程和保留，我们结合联合收割机时间序列的温度和比电导测量在图里克湖（阿拉斯加）和它的主要流入量，测量放电和气象学，和配置文件的比电导，温度，荧光，叶绿素，溶解有机碳（DOC）在3年的春天。融雪初期，溪流中DOC浓度为750 μM，是湖泊中DOC浓度的2倍。在缓慢融化期间（流量（Q）< 4 m3 s −1），进入的富含溶质的侵入物在冰下扩散到整个湖。在Q> 6 m3 s −1的融化过程中，流入的水部分冲洗了入口盆地，更稀的水流过原始侵入体，并优先流向出口。渗透对流的限制，从传入羽流的密度梯度增加，并最初限制到浅混合区与密度的阶跃变化。由于冰的厚度减少到小于1米，加热引起的密度不稳定性的入侵，混合溶质垂直10米，有助于保留的基础。富含DOC的近地表层在快速融化期间持续约10 d，在缓慢融化时持续超过3周。保留率约为10- 20%，也取决于熔体的速度和放电的大小。
The extent to which snowmelt flowing into ice‐covered lakes spreads horizontally and mixes vertically influences retention of solutes derived from the landscape. To quantify these transport processes and retention, we combine time series temperature and specific conductance measurements in Toolik Lake (Alaska) and its major inflow, with measurements of discharge and meteorology, and profiles of specific conductance, temperature, fluorescence, chlorophylla, and dissolved organic carbon (DOC) in spring of 3 yr. During early snowmelt, the concentration of DOC in the stream was 750 μM, twice that in the lake. During slow melt (discharge (Q) < 4 m3s−1), the incoming solute‐rich intrusion spread lakewide below the ice. During melt withQ> 6 m3s−1, the incoming water partially flushed the inlet basin and the more dilute water flowed over the original intrusion with a preferential flowpath to the outlet. Penetrative convection was restricted by the increased density gradients from the incoming plume and initially constrained to shallow mixing zones associated with the step changes in density. As ice thickness decreased to less than 1 m, heating caused density instabilities at the base of the intrusions that mixed solutes ∼ 10 m vertically, contributing to retention. Near‐surface layers enriched with DOC persisted for ∼ 10 d during a rapid melt and for over 3 weeks when the melt was slow. Retention, of order 10–20%, also depended on the rapidity of melt and magnitude of discharge.