三峡水库浮游植物群落特征及水体富营养化评价

基于2003—2017年三峡水库浮游植物群落结构、优势种群的变化和2017年水库干支流水质数据,全面分析浮游植物群落结构和演替特征,并运用综合营养状态指数法对水体富营养化程度进行评价。结果表明,三峡水库浮游植物种类丰富,监测期间共鉴定出浮游植物7门62属,细胞密度在7.5×10~4~2.8×10~7cell/L之间变化,Shannon-Wiener多样性指数为1.0~3.0,在α-中污带和β-中污带之间,说明三峡水库水生态环境健康状况相对较好;三峡水库浮游植物季节性演替特征呈硅藻和甲藻向蓝藻和绿藻演替的趋势,年际变化特征分析发现浮游植物密度在2008年175 m实验蓄水后大量增长,且优势藻类由河道型藻类向湖泊型藻类转化。通过监测数据分析,得出三峡水库干流处于中营养状态,支流在春季主要处于轻度富营养状态,秋季支流比春季支流的富营养化程度低,主要处于中营养状态,总氮(total nitrogen,TN)、总磷(total phosphorus,TP)和透明度(transparency,SD)为水质主要影响因子。

Characteristics of Phytoplankton Community and Eutrophication Evaluation of the Three Gorges Reservoir

Based on the changes of phytoplankton community structure and dominant species in the Three Gorges Reservoir from2003 to 2017 and the water quality data of the main stream and tributaries in 2017,the phytoplankton community structure and succession characteristics were comprehensively analyzed,and the eutrophication degree of the water body was calculated by the comprehensive nutritional status index method.The results showed that there were abundant phytoplankton in the reservoir.During the monitoring period,7 type and 62 genera phytoplankton were detected.The phytoplankton density varied from 7.5×10~4 to 2.8×10~7 cell/L,and the Shannon-Wiener diversity index from 1.0 and 3.0 was between theα-medium pollution zone andβ-medium pollution zones,indicating that the health status of the water ecological environment was relatively good.The seasonal characteristics of phytoplankton in the Three Gorges Reservoir showed the succession from diatoms and dinoflagellates to cyanobacteria and green algae.The interannual variation showed that the algae density increased significantly after experimental water storage of 175 m in 2008,and the dominant showed transformed from river-type algae to lake-type algae.Monitoring data analysis showed that the main stream of the Three Gorges Reservoir was in a medium nutrient state;the tributaries were mainly in mild eutrophication in spring,and the eutrophication was lower in autumn than in spring,mainly in a medium nutrient state.Total nitrogen(TN),total phosphorus(TP),and transparency(SD)were the main influencing factors of water quality.