青藏高原湖泊水化学与盐度的相关性初步研究

Preliminary Study of the Correlation between Hydrochemistry and Salinity of Lakes in the Qinghai-Tibetan Plateau

本文综合分析了青藏高原地区400多个湖泊的水化学成分(Mg2+、Ca2+、Sr2+、Sr/Ca和Mg/Ca)与湖水盐度的相关关系,以及这种关系随着湖水变化(不同采样时间和采样点以及蒸发实验)而产生的变化规律。认为:在青藏高原湖泊中,Mg2+与盐度具有较为稳定的正相关关系,而Ca2+、Sr2+、Sr/Ca以及Mg/Ca与盐度的相关性较弱且不稳定。而在特定的水化学类型的湖泊中,碳酸盐型湖泊的Mg2+、Ca2+以及Mg/Ca与盐度均没有明显的相关性。硫酸盐型湖泊中Mg2+和盐度呈现较高的正相关关系,而Ca2+以及Mg/Ca与盐度的相关性仍很弱。而在氯化物型湖泊中,Mg2+与盐度呈更强的正相关关系,Ca2+与盐度也呈一定的正相关关系,而Mg/Ca与盐度的相关性依然很弱。在特定的单个湖泊中,Ca2+以及Mg/Ca与盐度的相关性仍然不稳定或很弱,而Mg2+与盐度仍然保持明显的正相关关系。在青藏高原利用湖相沉积恢复特定湖区古环境演化序列的时候,Mg2+浓度是湖水古盐度一个较好的转换指标,而在应用Mg/Ca这一指标时应谨慎。

This study discussed the correlation between hydrochemical compositions （Mg^2＋,Ca^2＋,Sr^2＋,Sr/Ca and Mg/Ca） and salinities of water samples from over 400 lakes in the Qinghai-Tibet Plateau and its corresponding change rule with waters of different places. The result shows that in the Qinghai-Tibet Plateau,the lakes show stable positive relation between Mg^2＋and salinity,and poor and unstable relation between Ca^2＋,Sr^2＋,Sr/Ca and Mg/Ca. In specific water type lakes,however,there is no distinct relation between Mg^2＋,Ca^2＋ and Mg/Ca and salinity. In sulphate type lakes,Mg^2＋ shows positive relationship with salinity while Ca^2＋ and Mg/Ca remains poor relationship with salinity. But in chloride-type lakes,Mg^2＋ shows stronger positive relationship with salinity,and Ca^2＋ also shows to some extent positive relationship with salinity,but Mg/Ca still shows no clear relationship with salinity. In a single lake,the interrelation between Ca^2＋ and Mg/Ca and salinity is weak or unstable,while Mg^2＋ has remarkable positive relationship with salinity. Our research suggests that Mg2＋ content is a useful indicator for restoration of paleoenvironment and development sequence of given lakes in the Qinghai-Tibetan Plateau by means of lake deposition,but the value of Mg/Ca might need special attention when employed as an indicator.