贵州高原红枫湖水体理化特征与碳氮硅的时空分布研究

通过分析贵州红枫湖不同水文期水体理化特征与碳氮硅含量的时空分布,以期揭示西南山区深水性湖库水环境质量的周期性变化规律。结果表明,在平水期和枯水期,红枫湖水温、pH值、溶解氧、叶绿素a含量等水体上下层变幅较小,丰水期水深6 m左右有明显的分层现象,以溶解氧最为典型,分层期底层水中溶解氧降至1.0 mg/L以下。受外源有机物大量输入和湖内藻类生长的双重影响,丰水期湖泊中DOC含量较平水期和枯水期高。NO_3~--N和DON分别占TDN的23.3%~89.4%、7.4%~26.7%。夏季湖水底层滞水带缺氧条件有利于NH_4~+-N和NO_2~--N的生成,并导致溶解态硅的含量增高。相关性分析表明,贵州高原深水性湖库的季节性水质恶化事件与夏秋季节水体分层结构失稳密切相关。

Physicochemical Characteristics of the Overlying Water and Spatial-temporal Distribution of Carbon, Nitrogen and Silicon in Lake Hongfeng, Guizhou Province, China

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-a 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.