内蒙古三大湖泊近10年水化学特征变化及影响因素分析

Analysis of changes in water chemistry characteristics and influencing factors of three major lakes in Inner Mongolia in the last decade

内蒙古自治区三大湖泊达里湖、乌梁素海、呼伦湖受地理位置和气候环境影响显著,尤其是作为尾闾湖的达里湖已由淡水湖演化为中咸水湖。于2022年对达里湖、乌梁素海、呼伦湖进行调查采样,与收集的历史资料进行比对分析,采用Piper三线图、Gibbs图、空间差异分析、端元图、离子比值和相关性分析等方法,研究三大湖泊水化学特征及成因机制,利用三大湖泊主要离子浓度历年对比图分析近10年湖泊主要离子浓度变化,并从环境角度分析达里湖盐化原因。结果表明:1)达里湖、乌梁素海、呼伦湖的水化学类型分别为HCO_(3)^(-)-Na^(+)-Cl^(-)型、HCO_(3)^(-)-Cl^(-)-Na^(+)型、HCO_(3)^(-)-Na^(+)-Cl^(-)型。2)各湖泊变异系数较大的水化学组分空间分布表现为达里湖离子[HCO_(3)^(-)与总溶解性固体(TDS)]浓度呈现西部高、东部低的分布特征,乌梁素海离子(HCO_(3)^(-)与SO_(4)^(2-))浓度总体上呈现由四周向中部递减的变化趋势,呼伦湖离子(HCO_(3)^(-)与SO_(4)^(2-))浓度的空间分布受入湖河流离子浓度的影响。3)三大湖泊的水化学特征主要受蒸发作用和岩石风化作用的影响,其中达里湖受蒸发岩矿物与硅酸岩矿物共同作用的影响,乌梁素海和呼伦湖主要受硅酸岩矿物作用的影响,达里湖地下水存在阳离子吸附作用。4)近10年达里湖离子浓度整体呈逐年上升的变化趋势。达里湖湖面蒸发量远大于湖面降水量,加之河流补给量逐年减少,导致湖面萎缩以及湖水盐化程度逐渐增大。从根本上来讲,环境因素造成的入湖水量减少、蒸发量增大,最终促使湖泊盐化加快。

The three major lakes in Inner Mongolia Autonomous Region,Dali Lake,Ulan Suhai Lake and Hulun Lake,are significantly affected by geographical location and climatic environment.In particular,Dali Lake,as a tail lake,has evolved from a freshwater lake to a medium-salt lake.In 2022,Dali Lake,Ulan Suhai Lake and Hulun Lake were investigated,sampled and compared with the collected historical data.Piper three-line diagram,Gibbs diagram,spatial difference analysis,endmember diagram,ion ratio,and correlation analysis were used to study the hydrochemical characteristics and formation mechanism of the three lakes.The primary ion concentrations of the three lakes over the years were used to analyze the changes of the primary ion concentrations of the lakes in the past 10 years,and the reasons for the salinization of Dali Lake were analyzed from the perspective of environment.The results showed that:(1)The hydrochemical types of Dali Lake,Ulan Suhai Lake and Hulun Lake were HCO_(3)^(-)-Na^(+)-Cl^(-)type,HCO_(3)^(-)-Cl^(-)-Na^(+)type and HCO_(3)^(-)-Na^(+)-Cl^(-)type,respectively.(2)The spatial distribution characteristics of ions with large coefficient of variation in each lake were studied.The spatial distribution characteristics of ions(HCO_(3)^(-)and total dissolved solid(TDS))in Dali Lake were high in the west and low in the east.The ions(HCO_(3)^(-)and SO_(4)^(2-))in Ulan Suhai Lake generally showed a decreasing trend from the periphery to the middle.The spatial distribution of ions(HCO_(3)^(-)and SO_(4)^(2-))of Hulun Lake was affected by the ion concentration in its inflow rivers.(3)The hydrochemical characteristics of the three lakes were mainly affected by evaporation and rock weathering.Among them,Dali Lake was affected by the combination of evaporite minerals and silicate minerals,Ulan Suhai Lake and Hulun Lake were mainly affected by silicate minerals,and the groundwater of Dali Lake had cation adsorption.(4)In the past 10 years,the ion concentrations of Dali Lake had been increasing year by year.The evaporation of the lake surface of Dali Lake was much larger than the precipitation of the lake surface,and the river recharge was decreasing year by year,which led to the shrinkage of the lake surface and the gradual increase of the salinization of the lake water.Fundamentally speaking,environmental factors reduced the amount of water entering the lake and increased the evaporation,ultimately accelerating the salinization of the lake.