程海水质参数季节变化特征与空间异质性

Seasonal Variation and Spatial Heterogeneity of Water Quality Parameter in Chenghai

本文以2015年10月、2016年3月、2016年5月和2016年7月对程海的四次垂直剖面实测数据为基础,通过分析探讨温度、叶绿素、pH值和溶解氧等参数的变化特征,发现冬春季程海处于混合期,水质稳定,但在夏秋季水温发生分层后,叶绿素含量和pH值随着温跃层的上下移动而发生明显变化,尤其是随温度升高,溶解氧分层位置高于温跃层,导致溶解氧含量极低的水体厚度增加,加剧了底层沉积物中的营养盐释放,造成水体富营养化加剧和蓝藻水华爆发,对水安全造成威胁。由于程海整个湖盆北深南浅并受风浪扰动影响,使得南部湖区全年表层水温均低于北部湖区,导致整个湖区水生植物量自北向南逐渐降低。程海南部湖区水质优于北部湖区,表现出了明显的空间异质性。建议加强水质监测、掌握其变化规律及影响因素,搞清营养物质成分来源及湖泊自循环过程,采取科学措施,防止水质持续恶化。

Based on the monitoring data of four vertical cross-section in October 2015, March 2016, May 2016 and July 2016, the variation characteristics of water quality parameters, which include tem-perature, chlorophyll-a, pH and dissolved oxygen (DO) in Lake Cheng or Chenghai were analyzed. The results indicated that the lake water was well mixed in the winter and spring;during the pe-riod the water quality is stable. But when the water temperature stratified in summer and autumn, the content of chlorophyll and the value of pH changed substantially along with the vertical movement of thermocline. Especially, with the temperature rising, the position of stratified DO layer became higher than thermocline, leading to a thickening of water body with low DO content. This process induced the release of nutrients from the lake sediments and promoted eutrophication and cyanobacteria blooming. Moreover, as Lake Cheng is deeper in north while shallower in south, together with stronger wind-wave disturbance in the south, the surface water temperature in south was lower than that in the north all the year round. This situation resulted in the amount of aquatic plant in the lake reduced from north to south gradually. The water quality in south lake is better than that in north, showing an obvious spatial heterogeneity. We recommend that the lake water quality monitoring should be strengthened in order to have a full understanding of the lake water quality and take measurements to prevent further deterioration of the lake water quality.