WANG Liying, ZHANG Runyu, CHEN Jingan

（State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China）

Abstract：Lake Hongfeng in Guizhou Province was selected as the research object. Physicochemical characteristics of the overlying water and the spatial-temporal distribution of carbon, nitrogen and silicon during different hydro-periods were investigated, in order to reveal the periodic change of water environmental quality in southwestern mountainous deep-water lake and reservoir. Results show that water temperature, pH value, dissolved oxygen and Chl exhibit seasonal variations in Lake Hongfeng, with lower vertical amplitude during level and dry periods than flood seasons. Stratification obviously exists at about 6 m depth in flood season. Dissolved oxygen in the bottom water layer was lower than 1 mg/L. Concentration of DOC in the lake water was elevated during flood season, owing to the large amount of exogenous organic matter input and algal growth. NO3--N and DON account for 23.3%-89.4%, 7.4%-26.7%, respectively. The anoxic condition in hypolimnion is favorable to the formation of NH4+-N and NO2--N in summer, while leads to the increase of dissolved silicon. The correlation analysis shows that the seasonal deterioration events of water quality in the deep-water lakes and reservoirs, Guizhou plateau are closely related to the instable structure of water stratification layer in summer and autumn.

Key words：Lake Hongfeng; physicochemical characteristics; carbon nitrogen silicon; water stratification; plateau deep-water lake and reservoir

EARTH AND ENVIRONMENT Vol.45, No.4, Tot No.318, 2017, Page 383-389