中文摘要：

湖泊现代特征的调查和对比研究是湖泊学和古湖泊学研究工作的基础，青藏高原大部分湖泊目前仍缺少详细的基本特征考察资料．基于2009年9月实地考察，本文报道藏北高原腹地的两个内陆封闭大湖——扎日南木错和当惹雍错的水深分布和现代湖水基本特征．测深结果显示扎日南木错大部分湖区水下地形较为平坦，最大水深为71．55m；当惹雍错实测最大水深为214．48m，是青藏高原上已知最深的湖泊，也是我国已知的第二深水湖．湖水理化性质显示在垂直方向上两湖都呈现明显的分层结构，温跃层的温度梯度分别为1．1℃／m和0．57℃／m，当惹雍错底层水温最低仅为1．6℃；两湖表水层的电导率分别高达18500μS／em和12900μS／cm；两湖表水层pH都超过10，而底层水的pH都降低到5左右，上下层湖水显示了不同的酸碱性质．湖水电导率和溶解氧在温跃层都具有同步跃变特征，反映了温度对湖水性质的影响．

英文摘要：

investigation and comparative study of modem limnological features of lakes is a basal work of limnological and paleolimnological study, most lakes on Tibetan Plateau are now still lack of basic information. Tangra Yumco and Zhari Namco are two big inland close lakes which located in North-Tibet Plateau. Based on field investigation conducted in September,2009 ,we present water depth distribution and modern physicochemical features of the two lakes. Bathymetric survey show that most areas of Zhari Namco are relatively flat with the deepest area of 71.55m, and the deepest water depth of Tangra Yumco is 214.48m, thus being the deepest lake on Tibetan Plateau ever known, also the second deepest lake in China. Lake water show clear stratification of both lakes, temperature gradients of thermocline are 1.1 ℃/m and 0.57 ℃/m in Zhari Namco and Tangra Yumco, respectively, and the lowest temperature is 1.6℃ which is recorded in hypolimnion in Tangra Yumco. Conductivity in epilimnion of both lakes is 18500μS/cm and 12900μS/cm,respectively. Lake water pH exceeds 10 in epilimnion while decreasing to about 5 in hypolimnion of both lakes, showing different acidic and alkaline characteristics. Both conductivity and dissolved oxygen show synchronous abrupt changes in thermocline,indicating the influence of water temperature on physico-chemical characteristics of lake water.