小型封闭水体环境因子与叶绿素a的时空分布及相关性研究

Temporal and Spatial Distribution of Environmental Factors and Chlorophyll-a and Their Correlation Analysis in a Small Enclosed Lake

以崇明岛前卫村的一个小型封闭富营养化水体为对象,自2007年7月~2011年9月进行了约4 a的野外观测,研究了物化因子、水动力因素和叶绿素a（Chl-a）的时空分布特征及其相关性.结果表明,该水体Chl-a含量具有明显的时空差异性.Chl-a含量与水温、浊度、TN和TP均呈显著正相关关系,水温和营养盐是影响浮游植物季节动态的主要因素,浊度的季节变化是浮游植物生长的结果表征.Chl-a的空间差异性与不同水域水动力条件的差异有关,受风影响显著的水域（北河道）流速多分布在0.08~0.22 m·s-1范围内,Chl-a含量显著较低（平均浓度为53.11μg·L-1）.从流速与Chl-a的关系分析来看,流速与Chl-a浓度呈显著负相关关系,流速总体分布在0~0.10 m·s-1的水域Chl-a含量显著偏高（平均浓度为35.30μg·L-1）.该结果表明较大强度的水动力条件能够对富营养化封闭水体中浮游植物生长产生显著的抑制作用,可为相关水体的水华防治提供有益借鉴.

About four year＇s field observation was conducted from July 2007 to September 2011, in a small enclosed eutrophic lake located in Qianwei Village, Chongming Island. The temporal and spatial distribution of environmental factors （including physicalchemical factors and hydrodynamic condition） and chlorophyll-a （Chl-a） were studied and their correlation was analyzed. Results indicated that there were significant differences in the spatial and temporal distribution of Chl-a in the lake. Significantly positive correlation was found between Chl-a and water temperature, turbidity, TN and TP. Water temperature and nutrients were the main limited factors of seasonal changes of phytoplankton. It could be the result of phytoplankton growth that caused the seasonal change of turbidity. It was found that hydrological changes were the primary factor affecting the spatial difference of Chl-a concentration. Lower average Chl-a concentration （35.30 μg. L-1 ） was recorded in the north watercourse, in condition with higher wind driven flow velocity ranging from 0.08 m.s-1 to 0. 22 m-s-1. A strong negative correlation was found between Chl-a concentration and flow velocity. Higher average Chl-a concentration （53.11μg. L-1 ） was frequently found under flow conditions ranged from 0 m. s-1 to 0. 10 m. s1 These findings indicated that increasing hydrodynamic condition would significantly inhibit the growth of phytoplankton and reduce the risk of algae blooming in summer in these eutrophic water bodies.