| 引用本文: | 朱伟,陈怀民,王若辰,冯甘雨,薛宗璞,胡思远.2017年太湖水华面积偏大的原因分析.湖泊科学,2019,31(3):621-632. DOI:10.18307/2019.0302 |
| ZHU Wei,CHEN Huaimin,WANG Ruochen,FENG Ganyu,XUE Zongpu,HU Siyuan.Analysis on the reasons for the large bloom area of Lake Taihu in 2017. J. Lake Sci.2019,31(3):621-632. DOI:10.18307/2019.0302 |
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| 摘要: |
| 太湖流域及湖区经过一系列综合治理之后，截至2015年，水华面积逐渐减少，治理效果初见成效.然而，2017年太湖出现了前所未有的大面积水华（1403 km2），其原因成为各方面关注的热点问题.2011-2017年，在太湖贡湖湾和梅梁湾布置的6个采样点，每月2次分层采集水质和微囊藻密度数据、全太湖的营养盐和微囊藻密度数据、气象数据和水华面积数据，进行了水华面积偏大的原因分析.结果显示，2011-2017年期间，全太湖总氮（TN）的7年平均浓度为1.89 mg/L，总磷（TP）为0.076 mg/L，而2017年TN浓度为1.60 mg/L，TP浓度为0.083 mg/L，比7年平均TP浓度回升了9.0%.气温方面，2011-2017年7年平均气温为17.3℃，2017年比7年平均气温高出0.7℃.全太湖7年平均微囊藻密度为0.53×108 cells/L，而2017年为1.18×108 cells/L，比7年平均值高出1.21倍.在这样一个数据背景下，全太湖年均值和风速区间比例冗余分析表明TP的回升、气温的偏高与水华面积也表现出明显的正相关关系，且5-9月1~2 m/s弱风天数与水华面积呈显著正相关，而风速超过4 m/s则会显著造成水华的消失.综合以上数据及分析，2017年出现巨大面积水华是由于全湖TP浓度的上升和气温偏高使微囊藻密度增长，为微囊藻聚集形成水华提供了丰富的物质基础，而在微囊藻大量繁殖季节风力较弱，1~2 m/s左右风速易于使微囊藻聚集形成薄层大面积水华. |
| 关键词: 太湖 水华面积 风速 气温 总磷 微囊藻密度 |
| DOI：10.18307/2019.0302 |
| 分类号: |
| 基金项目:国家水体污染控制与治理科技重大专项（2017ZX07603-003-04）和江苏省科技计划项目（BE2018737）联合资助. |
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| Analysis on the reasons for the large bloom area of Lake Taihu in 2017 |
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ZHU Wei1,2, CHEN Huaimin1, WANG Ruochen1, FENG Ganyu1, XUE Zongpu1, HU Siyuan1
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1.College of Environment, Hohai University, Nanjing 210098, P.R.China;2.Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, P.R.China
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| Abstract: |
| After a series of comprehensive restoring, the area of Microcystis blooms in Lake Taihu Basin has gradually decreased by 2015, and preliminary results were achieved. However, in 2017, an unprecedented expansion of the Microcystis blooms area (1403 km2)occurred in Lake Taihu, and the reason behind which has become a focus of researchers' attention. In this study, water quality and Microcystis cell density data, nutrient and Microcystis cell density data, meteorological data and blooms area data were collected twice a month from 6 sampling sites in Gonghu Bay and Meiliang Bay of Lake Taihu from 2011 to 2017. The results showed that the 7-year average concentrations of total nitrogen (TN)and total phosphorus (TP)in Lake Taihu was 1.89 and 0.076 mg/L in 2011-2017, while in 2017 TN concentration was 1.60 mg/L and TP concentration was 0.083 mg/L, which was 9.0% higher than the 7-year average TP concentration. In terms of temperature, the average temperature in 2011-2017 was 17.3℃, while in 2017 it was 18.0℃, which was 0.7℃ higher than that in 7 years. The average cell density of Microcystis in Lake Taihu in 7 years was 0.53×108 cells/L, while in 2017 it was 1.18×108 cells/L, which was 2.21 times of the average in 7 years. In such a data background, RDA annual mean analysis and wind speed interval proportion analysis results indicated that the rise of TP concentration and the high temperature also showed a significant positive correlation with the area of Microcystis blooms. And the number of weak wind days from May to September has the greatest impact on the area of algal blooms, while the wind speed of more than 4 m/s would significantly reduce the probability of large-scale outbreaks. Based on the above data and analysis, the large area of algal blooms in 2017 is attributed to the increasing of Microcystis cell density due to the rise of TP concentration and high temperature in the whole lake, which provides a rich material basis for the formation of Microcystis blooms. Futhermore, the weak wind in the season of large-scale propagation of Microcystis. The wind speed of about 1-2 m/s is easy to facilitate Microcystis aggregation and Microcystis blooms formation. |
| Key words: Lake Taihu bloom area wind speed air temperature total phosphorus Microcystis cell density |
