Hydrographic Features of Sêrling Co, North Tibetan Plateau

Abstract

本文报道了1997年和1998年夏季对藏北色林错等水体水文特征的考察情况.结果表明,色林错是一个大型深水湖泊,表层水温在下午4:30左右达到最高,清晨7:30左右时最低.浅水区域表层湖水在6月份的极端最高水温为21.2℃,极端最低水温为11.0℃,而日平均水温变幅仅5.6℃,其幅度大于在同一时段湖区内不同区域之间表层水温的变化.色林错湖水的pH值较高,为9.19-9.66;表层水的pH昼夜变化较小,仅0.15,最高值出现在凌晨,同时水体不同区域及深度的pH值基本一致.其溶解氧变化在4.62-5.12mg/L,而且不同深度水层之间的变幅较小,仅0.03-0.35mg/L;但其湖汊浆东如瑞溶解氧的昼夜变幅为4.58-5.59mg/L;盐度的日变幅为1.60%-2.20%.考察表明,藏北水体的盐分有一个从河流到湖泊、以及由流水向静水富集的趋势;鱼类的分布与水体盐分的含量密切相关,即鱼类随着水体盐分的增加而消失,代之以嗜盐性卤虫的出现及大量繁衍.;The area of lakes in Qinghai-Tibetan Plateau is one of the largest and the highest lake district in the world, most of which lie on the north Tibetan Plateau (Qiang tang Plateau)with an average altitude of more than 5000m a.s.l.In the summers of 1997 and 1998, we investigated the hydrog raphic features of Sêrling Co, north Tibetan Plateau.The hourly maximum temperature of epilimnion occured at 4:30 a.m.and the minimum w as at 7:30 p.m.The maximum temperature of epilimnic shallow region could reach at 21.2℃ and the minimum was 11.0℃ in June.The range of daily mean temperature of epilimnion was only 5.6℃ and was larger than the difference of that w as co rrespo ndingly tested among different regions in Sêrling Co.The water pH value of epilimnio n in the lake varied from 9.19 to 9.66.However, the range of hourly pH value in shallow region was only 0.15 and the maximum occured in the early morning, w hich differs from other lakes such as the lowland lakes in east China.The dissolved oxygen v aried f rom 4.62 mg/L to 5.12 mg/L and the changes among dif ferent deep regions w ere only 0.03-0.35 mg/L in Sürling Co.Hourly gradient of dissolved oxygen of epilimnion varied f rom 4.85 mg/L to 5.59 mg/L in Jiang dongrurui (aquene of Sürling Co), 4.72-5.35mg/L in the mouth of Boquzangbu and 4.54-5.93 mg/L in the low er reaches of Boquzangbu.The hourly minimum of dissolved o xygen in Jiangdong rurui and Boquzangbu occured at 4:30 p.m., and in the outlet of Boquzangbu at 7:30 a.m.The times that maximum dissolved oxygen observed were so different and occurs respectively at 10:30 p.m., 7:30 p.m.and 10:30 a.m.in the regions above-mentioned respectively, which proved that the dissolved oxygen could be influenced by water temperature and hydrobiological activities.The hourly salinity of epilimnion in the lake varied f rom 1.6-2.2% and the maximum occured at 4:30 to 7:30 a.m.In the inland water bodies of north Tibetan Plateau, i t is obvious that there is a concentrical tendency of salinity from st reams to lakes and from running water to still water.The dist ribution of fishes is correlative wi th the salinity of waters.Consequently, fishes disappear and are replaced by salinella with the increasing salini ty in water bodies.