三峡库区支流澎溪河水华高发期环境因子和浮游藻类的时空特征及其关系

分别在2014年春季和夏季三峡库区水华高发期,在库区北岸最大支流澎溪河流域从其河口处逆流而上至回水末端共布置8个采样点,对浮游藻类和环境因子进行了监测,运用数理统计分析手段,对浮游藻类的群落结构及其与环境因子的关系进行了分析.结果表明在4月中旬,除河口样点外,其他采样点水体出现分层,但断面多只有温跃层和滞温层,而没有混合层;上游水体层次间温差高于下游水体;各采样点的水深以及表层水体(水面向下至0.5 m深的水层)的水温、浊度、p H、电导率、溶解氧、叶绿素a、总氮和总磷的空间分布差异显著(ANOVA,P0.05);共检测到浮游藻类25种(属),丰度在(2.76~145.8)×10~4cell·L~(-1)之间,以角甲藻(Ceratium hirundinella)为主要优势藻,鱼腥藻(Anabaena sp.)为次优势藻;上游接近支流来水的样点S7(63.4×10~4cell·L~(-1))和S8(145.8×10~4cell·L~(-1))水华最为严重;硝酸盐氮、水温、p H、电导率和溶解氧是藻类生长的决定因子.在7月下旬,水体分层,趋势与春季相似;各采样点深度和0~0.5 m水层的水温、浊度、氧化还原电位、p H、电导率、叶绿素a、氨氮、硝酸盐氮、总氮和总磷的空间分布仍然差异显著(ANOVA,P0.05);共检测到浮游藻类46种(属),丰度在(9.56~278.88)×10~4cell·L~(-1)之间,总体以席藻(Phormidium sp.)为主要优势藻,鱼腥藻(Anabaena sp.)为次优势藻;下游接近澎溪河河口的样点S2(216.44×10~4cell·L~(-1))、S3(278.88×10~4cell·L~(-1))和S4(108.12×10~4cell·L~(-1))水华严重;浊度、水深、总氮、氧化还原电位、电导率和溶解氧是藻类生长的决定因子.水体分层与水华形成有重要关系.

Temporal and Spatial Distribution of Environmental Factors and Phytoplankton During Algal Bloom Season in Pengxi River, Three Gorges Reservoir

Planktonic algae and Related Environmental Factors were monitored during the period of algal blooms season in 2014 (Spring April 17 and summer 27 July) in Pengxi river, Three Gorges Reservoir. Mathematical statistical tools were used to analyze the community structure of planktonic algae in Pengxi River with its environmental factors. The results of sampling in spring showed that except the estuary site, S1 and the site close by, S2, the waters stratified, but without epilimnion, only had metalimnion and hypolimnion; the upstream sites had larger temperature difference between water layers than did the downstream ones; from all the 8 sampling sites from estuary to upstream, water depth, and the temperature, pH, conductivity, dissolved oxygen, chlorophyll a, TN and TP of the surface layer (0-0.5 m deep) were significantly different (ANOVA, P<0.05). 25 species (genus) of planktonic algae were identified. The abundance of species ranged from 2.76×10⁴ cell ·L^-1 to 145.8×10⁴ cell ·L^-1. Ceratium hirundinella was the main dominant species, and Anabaena sp. was the sub-dominant species. Algal bloom in upstream sampling sites S7 (63.4×10⁴ cell ·L^-1) and S8(145.8×10⁴ cell ·L^-1)were relatively serious in spring. Temperature of water, pH, conductivity, dissolved oxygen and NO₃^- were the key regulatory factors for phytoplankton abundance based on redundancy analysis (RDA). The results of sampling in summer showed similar stratification trends among sites; the depth of the same 8 sampling sites, and their surface layer's temperature of water, turbidity, redox potential, pH, water depth, conductivity, chlorophyll a, NH₄⁺,NO₃^-,total nitrogen and total phosphorus were significantly different (ANOVA, P<0.05). 46 species (genus) of phytoplanktonic algae were identified. The abundance ranged from 9.56×10⁴ cell ·L^-1 to 278.88×10⁴ cell ·L^-1. Phormidium sp. was the main dominant species, and Anabaena sp. was the sub-dominant algae. Algal bloom at the lower part of the river, S2 (216.44×10⁴ cell ·L^-1), S3(278.88×10⁴ cell ·L^-1)and S4 (108.12×10⁴ cell ·L^-1) were relatively serious in summer. Turbidity, depth of water, TN, oxidation-reduction potential, conductivity and dissolved oxygen were the key regulatory factors for phytoplankton abundance based on RDA. Stratification had important effect on algal bloom formation.