河西走廊黑河流域地下水化学特征研究

黑河流域地处西北内陆干旱区,受径流蒸发和溶滤作用的控制,地下水水化学最重要的特征是自补给区至排泄区具有典型的水平分带性和垂直倒置分异规律。水平方向从祁连山山前洪积扇顶部到冲、洪积细土平原北部的盐沼(盐地),表层地下水的矿化度随着径流长度的增加而增高,由淡水过渡为咸水并达到卤水阶段,化学组分亦相应的由HCO3--Na -Ca 型递变为SO42--HCO3--Na -Ca2 型、SO42--Cl--Na -Ca2 型直到Cl--SO42--Na 型、Cl--Na 型,每个水化学带与一定的地貌单元相联系。垂向上在淡承压水分布的区域,上部潜水矿化度0.5～4.0g/L,下部承压水矿化度小于1g/L,且随着深度的增加矿化度降低。

Hydrochemical Characteristics of Groundwater of the Heihe Basin in the Hexi Corridor, Gansu Province

The Heihe basin is located in the inland arid district,northwest China. Controlled by surface runoff evaporation and percolation, the hydrochemistry of groundwater is characterized by the horizontal zonation and vertical upside-down differentiation from the supply sources to the discharge area. Horizontally , from the top of pluvial fans in the front of the Qilian mountains to the salt marsh (salt land) in the north of the alluvial-pluvial plain made up of by soil, the mineralization degree of the top layers of groundwater becomes higher as the runoff length increases , accompanied by fresh water to salt water and even to brinestage. Accordingly, the chemical components gradually change from HCO-3-Na -Ca2 type to SO2-4-HCO-3-Na -Ca2 and SO2-4-Cl--Na -Ca2 types , and then became Cl--SO2-4-Na and Cl--Na types, and during the change, each hydrohemical zone is closely related to a certain geomorphical unit. Vertically, in fresh water of unconfined aquifer, the mineralization degree decreases as the depth increases, in the top is about 0.5~4.0g/L, while in water of confined aquiferit becomes lower than 1 g/L.