A fifteen-month field observation was conducted from April 2013 to June 2014 in Xili Reservoir,a public drinking water supply reservoir in Shenzhen.The spatial and temporal distribution of environmental factors and chlorophyll-a concentration were studied,and their relationship was analyzed.The results indicated that the average of ρ(TChla) was 16.84 μg/L,ranging from 2.65-60.35 μg/L.The annual average ρ(Chla) of Cyanophyta was 7.34 μg/L,ranging from 0.77-30.58 μg/L.The annual average ρ(Chla) of Bacillariophyta was 7.81 μg/L,ranging from 0.77-31.62 μg/L.The annual average ρ (Chla) of Vhlorophyta was 3.31 μg/L,ranging from 0.77-12.71 μg/L.Cyanophyta was the primary species in the rainy season,while Bacillariophyta was the primary species in the other months.There was obvious spatial heterogeneity in the community of phytoplankton at Xili Reservoir.Chlorophyll-a concentration decreased gradually from the northwest to the southeast.In the rainy season,ρ (Chla) near Baimang River was very high,and there was a risk of algal blooming.Wind blew at 2.7 m/s from the southwest in the rainy season.As a result,phytoplankton moved in the wind's direction,reducing the risk of algal blooming in the western reservoir.The spatial heterogeneity of flow field at Xili Reservoir was obvious.The water flow rate was 0.005-0.025 m/s,and the leading flow was from the northeast to the southwest.High concentrations of algae in the western part of Xili Reservoir were diluted by the leading flow.The results of Pearson correlation analysis and canonical correspondence analysis revealed that water temperature (WT),ρ(TOC) and rain capacity were the most significant factors for algal blooms.Phosphorus was the restricting factor of algae growth.%以典型亚热带供水型水库——西丽水库为研究对象,对其2013年4月-2014年6月藻类ρ(Chla)及其相关环境因子进行监测,分析了藻类ρ(Chla)时空演变规律及其与环境因子的关系.结果显示:西丽水库ρ(TChla)(TChla为总叶绿素a)为2.65～60.35 μg/L,其中蓝藻ρ(Chla)为0.77 ～ 30.58 μg/L,硅藻ρ(Chla)为0.77 ～ 31.62 μg/L,绿藻ρ(Chla)为0.77～ 12.71 μg/L.汛期(6-9月)优势藻为蓝藻,其他时期硅藻占优势,绿藻全年处于较低水平.藻类分布具有明显的空间异质性,ρ(Chla)整体呈西北库区高东南库区低的特点,汛期白芒河入库区域ρ(Chla)偏高,存在一定的藻华风险.汛期盛行西南风,平均风速为2.7 m/s,有利于藻类自高浓度的西部库区向东迁移,一定程度上降低了藻华风险.水库流场空间差异较大,水体流速为0.005 ～0.025 m/s,水库主导流向为东北—西南,对西北库区的高浓度藻类起到稀释作用.Pearson相关分析和典范对应分析(CCA)显示,温度、有机物以及径流量是影响藻类生长和分布的前三位因子,磷是藻类生长的限制性营养盐.
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