广东韩江潮州段浮游植物群落结构特征与水质评价

为探究广东韩江潮州市饮用水源保护江段浮游植物群落结构特征及水质富营养化状况，于2019年2月至2020年1月在潮州段设立4个采样点，进行浮游植物群落结构和水质定点监测。结果表明，韩江潮州共鉴定出浮游植物290种，隶属8门103属，其中绿藻门42属99种，硅藻门21属87种，蓝藻门24属70种。全年有9个月的种类组成以硅藻门为绝对优势种，绿藻门仅在6、9、10月种类数多于硅藻门，表明该江段浮游植物组成为硅藻-绿藻型。浮游植物丰度月变化在0.83×106～1.99×106个/L，月均丰度为0.90×106 个/L，全年以硅藻门丰度最高，占47.01%。优势种11种，硅藻门5种，隐藻门4种，蓝藻门和裸藻门各1种，其中颗粒沟链藻(Melosira granulata)是绝对优势种。Shannon-Wiener多样性指数（H）为3.14～5.08，平均值4.40；Pielou均匀度指数（J）为0.69～0.99，平均值0.87；Margalef丰富度指数（D）为2.60～6.85，平均值5.08，表明水质为轻度污染。Cluster聚类和NMDS排序分析显示，物种构成可分为2个类群，类群I包括2019年2–7月，类群II包括2019年8–12月和2020年1月。Pearson相关性和冗余分析表明，影响浮游植物优势种的水环境因子主要是透明度和亚硝态氮，影响颗粒沟链藻分布的是盐度和水温，影响隐藻门分布的主要是透明度、pH和水温。参照地表水环境质量标准，韩江潮州段为Ⅱ类水，多样性指数显示为轻度污染，浮游植物群落结构和优势物种显示水体为偏中营养型。

Phytoplankton Community Structure and Water Quality Assessment of the Chaozhou Section of Hanjiang River

Hanjiang River is the second largest river in Guangdong Province and serves as the drinking water source for eastern Guangdong. In this study, we characterized the phytoplankton community structure and eutrophication status of the Chaozhou section of Hanjiang River, which is the drinking water source for Chaozhou City. From February 2019 to January 2020, phytoplankton and water quality monitoring was carried out monthly at 4 sampling sites, focusing on phytoplankton community structure, dominant species, diversity indices, pollution indicator species and 11 water environment parameters. Our aim was to provide data for aquatic ecosystem evaluation and water quality monitoring of Hanjiang River, and to provide a reference for developing a management strategy for maintaining a healthy and safe environment of drinking water source. A total of 290 phytoplankton species from 103 genera and 8 phyla were identified, including Chlorophyta (99 species, 42 genera), ?Bacillariophyta?(87 species, 21 genera) and Cyanophyta (70 species, 24 genera). While species richness of the diatom phylum was absolutely dominant for nine months of the year, Chlorophyta had higher species richness in June, September and October. Thus, the phytoplankton community of the river section was of the diatom-green algae type. The monthly abundance of phytoplankton varied from 0.83×106 to 1.99×106 cells/L, with an average abundance of 0.90×106 cells/L. The abundance of diatoms was the highest, accounting for 47.01% of the total. There were 11 dominant species identified during the investigation, consisting of 5 Bacillariophyta species, 4 Cryptophyta species, 1 Cyanophyta species and 1 Euglena species, among which Melosira granulata was the absolutely dominant species. The Shannon-Wiener diversity (H), Pielou evenness (J) and Margalef richness (D) indices were in the range of 3.14-5.08, 0.69-0.99 and 2.60-6.85, with the average values of 4.40, 0.87 and 5.08, respectively, indicating a slightly polluted condition. Cluster analysis and NMDS ordination results show that phytoplankton communities from February to July 2019 was clustered into one group, and communities from August to December 2019 and January 2020 was clustered into another group. Pearson correlation and redundancy analysis show that transparency and nitrite nitrogen were the primary water environmental factors affecting the dominant species of phytoplankton. The factors affecting the distribution of Melosira granules were salinity and water temperature, and the factors affecting the distribution of Cryptophyta were transparency, pH and water temperature. According to the environmental quality standard of surface water, the Chaozhou section of Hanjiang River met the standard of Class II surface water. The diversity indices also indicated that the water was lightly polluted. Analysis of phytoplankton community structure and dominant species indicated that the water is mesotrophic.