Cadastre and hydrochemistry of high altitude lakes in the Mount Everest region

Summary

At between height 4200 and 5800 m a.s.l. in the Khumbu Himal region, Nepal, 73 lakes have been identified and catalogued according to geography, height, catchment area and lake area. From 1989 to 1994 approximately 50% of the lakes were surveyed. Water samples were collected from 24 and the following determined: pH, conductivity, oxygen, total alkalinity, ammonium, calcium, magnesium, sodium, potassium, nitrate, sulfate, chloride, silicate, total phosphorus, nitrogen, and up to ten trace metals in addition to Al, Fe and Mn.

Calcium, total alkalinity and sulfate dominated the chemistry of these waters, while ammonium, nitrate and chloride were present in very low concentrations (between <0.2–5 μeq/L); total nitrogen and phosphorus concentrations were typical of oligotrophic water bodies and nitrogen mainly occurred in organic form (TON). This preliminary investigation forms the basis of a proposal for an extensive investigation of high altitude lakes in the Himalayas in order to assess global changes due to anthropogenic pollution.