四川省阿坝地区地表水地球化学特征

阿坝州位于四川西北部,与青海、甘肃交界,处于高海拔地区;该地区地表水资源丰富,长江与黄河上游水系均流经该区域。通过系统性采集区内河水(76件)、井水(7件)、溪水(8件)等样品,测试水体中D与~(18)O的丰度与微量元素含量。结果表明:1受大气降水与流经地层的影响,阿坝地区河水中D与~(18)O的丰度均显著高于溪水、井水与自来水等介质,线性相关性表明,河水中~(18)O的富集与硫酸盐矿物的溶解密切相关;2阿坝地区井水、自来水、溪水之间存在明显的水力联系;3对于阿坝地区而言,黄河上游河流中δD与δ~(18)O值均高于长江上游水系河流,但两者之间差别较小,这由于同一地区水系具有相同的大气降水来源;4河水、井水、溪水等表水中微量元素呈高Ba、Zn、Cr,低As、Pb、Cd的特点,与该地区岩石样品中微量元素特征基本一致,表明该地区表水中微量元素含量主要受地质背景因素控制。

Characteristics of Hydrogen,Oxygen Isotopes and Trace Elements in Surface Water of Aba Area in Sichuan

Aba is a region with high altitude, located in the northwest of Sichuan, and at the junction with Qinghai and Gansu provinces. Aba is rich in surface water resources that the Yangtze River and Yellow River both flow across this area. Through systematically sampling the rivers water (76), wells water (7) and streams (8), and analyzing the contents of ¹⁸O, D and trace elements in water, we revealed that ① The contents of D and ¹⁸O in river water of Aba were significantly higher than streams, wells and tap water. Linear correlation analysis indicated that the enrichment of ¹⁸O was closely related to the dissolution of sulfuric minerals; ② There was obvious hydraulic link among well water, tap water and streams in Aba; ③ In Aba, isotopic composition of oxygen and hydrogen in river water of Yellow River system were closing to that of Yangtze River system, which was due to the same rainfall source at the same area; ④ The trace elements of surface water were quite close with the surrounding rocks, with the characteristics of high concentrations of Ba, Zn, Cr, and low concentrations of As, Pb, Cd, which indicated that the trace elements in surface water was mainly affected by the geological background.