藏南羊卓雍错湖水化学空间分异特征

2010年7月对藏南羊卓雍错流域进行了水样采集,通过测定与分析,揭示了流域最大湖泊羊卓雍错表层湖水化学水平分布特征和深水剖面变化规律,并探讨了该湖与流域其他水体化学性质的差异。结果表明:流域特殊的高寒气候、湖泊形状与补给来源、湖岸水系发育程度不同是造成羊卓雍错湖水化学空间分异特征明显的关键。在水平方向上,湖水HCO3-、Ca2+以及矿化度南高北低,而SO42-和Mg2+南低北高。这是由于湖水从南向北缓慢流动过程中蒸发浓缩所致;卡鲁雄曲径流量经空姆错补给羊卓雍错北部,使其矿化度较低。在垂直方向上,愈向湖泊深处,湖水SO42-、Cl-、CO32-和矿化度愈大,HCO3-则降低。与流域其他湖泊相比,羊卓雍错水化学性质与同属以降水补给为主的湖泊相近,与以冰雪融水补给为主的湖泊差异显著。与河水和地下水相比,羊卓雍错湖水SO42-和Mg2+当量浓度最大,河水和地下水则HCO3-和Ca2+含量较大。

Spatial Differentiation of Water Chemical Property in Yamzhog Yumco,South Tibet

On the basis of water sample collection and chemical parameter measurement,spatial differentiation of water chemical property of Yamzhog Yumco,the largest lake in Yamzhog Yumco Basin,south Tibet,was studied by analyzing the concentration changes of parameters at horizontal and vertical directions of the lake,and by comparing it with other lakes,rivers and wells of the basin in general water chemical properties.Results indicated that it is the particular alpine climate,lake shape and supplement sources,and inflow river drainage that accounts for obvious spatial differentiation of water chemical property of Yamzhog Yumco.The concentrations of SO42-and Mg2+ in north area are relative higher than that in the south,while distributions of HCO3-and Ca2+ are just the opposite due to high evaporability of lake water flowing from the south to the north area of Yamzhog Yumco.Mineralization degree concentration in the north area,however,is relative lower than that in the south,which is attributed to the large amount supplement of inflow of Kaluxiong River through Kongmu Co with low mineralization degree.The concentrations of SO42-,Cl-,CO32-and mineralization degree increase with lake depth.On the contrary,the concentration of HCO3-decreases with lake depth.Water chemical property of Yamzhog Yumco is similar to that of lakes supplied overwhelmingly by rainfall,which is in sharp contrast to lakes supplied mainly by glaciers.Comparing with water chemical property of rivers and wells in the basin,the concentrations of Mg2+ and SO42-are much higher in Yamzhog Yumco with relative lower concentrations of Ca2+ and HCO3-.