溶解氧对湖库热分层和富营养化的响应——以枣庄周村水库为例

为研究热分层和富营养化对湖库溶解氧变化特征的影响,于2014年1月~12月对周村水库水温、溶解氧、叶绿素以及初级生产力的季节变化及垂向分布进行了监测.结果表明:水温和溶解氧的分层期均为4~11月份;分层期叶绿素在20~50μg/L之间,初级生产力为2.16~2.23gO₂/(m³·d),光补偿点在1~3m之间;恒温层在5月中旬进入厌氧状态;由于光补偿点位置较高,5~8月份氧跃层位置为1~6m,高于温跃层上界面;而氧跃层位置偏高造成溶解氧在垂向上的极值一般在表层,且变温层溶解氧浓度梯度较大;9~11月份温跃层的下移使得氧跃层和厌氧区界面同时下移,厌氧区界面与温跃层上界面的位置变化始终同步,而氧跃层受水体耗氧作用的影响在热分层结构相对稳定时会再次上移.热分层和水体富营养化均对溶解氧的浓度和分布有重要的影响.

Responses of dissolved oxygen on thermal stratification and eutrophication in lakes and reservoirs—An example in Zhoucun Reservoir in Zaozhuang City

To investigate the effects of thermal stratification and eutrophication on dissolved oxygen, seasonal variations and vertical distribution of water temperature, dissolved oxygen, chlorophyll a and primary production were monitored from January 2014 to December 2014 in the Zhoucun Reservoir. The results showed that water temperature and dissolved oxygen both experienced stratification from April to November. The chlorophyll a was 20~50μg/L, the primary productivity was 2.16~2.23g O₂/(m×d) and the position of light compensation point was between 1m and 3m during stratification. The hypolimnion has been in anaerobic condition since mid-May. Because of the high position of light compensation point, the oxycline's position was between 1m and 6m during stratification, higher than thermocline's. The maximum value of dissolved oxygen was usually at the surface since the position of oxycline was high and the dissolved oxygen gradient was large in the empilimnion. The vertical migration of thermocline made oxycline and anaerobic zone interface both moved down between September and November. The anaerobic zone interface' position was always the same as thermocline's, while the oxycline would move up again when the thermal structure was relatively stable. The thermal stratification and eutrophication have significant effects on dissolved oxygen concentration and distribution.