Geochemistry of the active layer and near-surface permafrost, Mackenzie delta region, Northwest Territories, Canada
Geochemistry of the active layer and near-surface permafrost, Mackenzie delta region, Northwest Territories, Canada
复制标题
DOI：
10.1139/e04-089
复制
发表时间：
2005-01-01
影响因子：
1.4
通讯作者：
Burn, CR
中科院分区：
文献类型：
--
作者：
Kokelj, SV;Burn, CR
测定了加拿大西北地区麦肯齐三角洲地区41个地点的活动层和近地表永久冻土的可溶性离子含量。在三角洲土壤中，Ca（2+）和Mg（2+）是主要的可溶性阳离子，但Na（+）的数量和相对丰度随着靠近波弗特海岸而增加。经常被洪水淹没的地表下的土壤与十年一次的洪水水平以上的土壤相比，具有丰富的离子。在同一地形类型中，近地表永久冻土土壤溶质浓度在距离小于1 m的成对岩心之间相似，但在较大距离（岩心间距为3-13 m），溶质浓度显著不同。在伊努维克附近的老高地表面，相对较低的土壤溶质浓度可能是由于在深度解冻期间，从活动层和永久冻土中逐渐去除可溶性物质的结果。在砂质粉土冲积层中，在向下冻结过程中被排除的溶质可能积聚在活动层的底部，并被上升的永久冻土层所隔离。在粒度较细的粘土粉砂区，冰区与阳离子富集区之间的对应关系表明，在活动层冻结回冻过程中，水和溶质的耦合运动与沉积冰的发育有关。近地表永久冻土层的溶质富集在细粒富冰冲积地最大，其永久冻土层的平均浓度高达活动层的7.5倍。
The soluble ion content of the active layer and near-surface permafrost was determined at 41 sites in the Mackenzie delta region, Northwest Territories, Canada. In delta soils, Ca(2+) and Mg(2+) are the dominant soluble cations, but the quantity and relative abundance of Na(+) increase with proximity to the Beaufort Sea coast. Soils beneath frequently flooded surfaces are ion rich in comparison with ground above the level of decadal flooding. Within a terrain type, near-surface permafrost soil solute concentrations are similar between paired cores spaced < 1 m apart, but at greater distances (cores spaced 3-13 m apart), solute concentrations are significantly different. Comparatively low soil solute concentrations in old upland surfaces near Inuvik may be a result of progressive removal of soluble materials from the active layer and permafrost during periods of deeper thaw. In sandy silt alluvium, solutes excluded during downward freezing may accumulate at the base of the active layer and be sequestered by a rising permafrost table. At sites with finer grained clayey silts, the correspondence between zones of ice and cation enrichment indicates coupled movement of water and solutes during freeze-back of the active layer and development of aggradational ice. Solute enrichment of near-surface permafrost is greatest at fine-grained ice-rich alluvial sites, where mean concentrations in permafrost are up to 7.5 times greater than those in the active layer.