太湖蓝藻生长与水质、气候因素的相互作用分析

Interaction Analysis on Blue Algae Growth with Water Quality and Meteorological Factors in Taihu Lake

根据2001-2018年太湖湖体水资源质量评价指标、主要污染物浓度指标,以及1980-2010年环太湖气象观测站累年日均气象要素观测值,利用区域相关指标分析水质和气象两方面对太湖蓝藻水华的影响情况和作用机理。结果表明:①近二十年太湖湖体各污染物浓度指标在不同程度上都呈现下降趋势,其中总氮、氨氮浓度变化最为明显,分别下降54.4%、25.1%。2008-2017年,经过十年治理,太湖已完全消除重度富营养状态,平均营养指数在60.5-63.5之间波动,且占比稳定,部分湖区已达到轻度富营养化。②叶绿素a与总氮和氨氮、总磷和高锰酸盐指数相关系数绝对值呈现出变化同步性,说明二者共同作用于蓝藻生长。其中,总氮和叶绿素a的相关系数在0.237-0.752之间,呈现低度相关;高锰酸盐指数与叶绿素a的相关系数最大为0.885。③环太湖地区在蓝藻爆发期(即7-8月)气温接近30℃时,风速主要分布在2.5-3m/s,在蓝藻复苏、生长期(即4-5月)气温小于20℃、风速介于2-3m/s的发生概率最大,为39.3%,为蓝藻提供了极其适宜的生长条件,使得夏季更容易出现大面积水华爆发。

According to the evaluation index of water quality of Taihu Lake from the year 2001 to 2018,the concentration index of main pollutants,and the annual daily average meteorological element observation value of the meteorological observation station around Taihu Lake from 1980 to 2010,the influence and mechanism of water quality and meteorology on cyanobacteria bloom in Taihu Lake were analyzed by using regional relevant indexes.The results show that:1.In the past 20 years,the concentration indexes of pollutants in Taihu Lake showed a decreasing trend in different degrees,among which the concentration changes of total nitrogen and ammonia nitrogen were the most obvious,reducing by 54.4%and 25.1%respectively.After ten years treatment,from 2008 to 2017,severe eutrophication in Taihu Lake has completely eliminated,with the average nutrition index fluctuating between 60.5 and 63.5,and the stable proportion appears.In some areas,the water has reached mild eutrophication.2.The absolute values of correlation coefficients of chlorophyll a with total nitrogen and ammonia nitrogen,total phosphorus and permanganate index show synchronous changes,which indicates that the two jointly act on the growth of cyanobacteria.The correlation coefficient of total nitrogen and chlorophyll a is between 0.237 and 0.752,showing low correlation.The maximum correlation coefficient between permanganate index and chlorophyll a is 0.885.3.When the temperature in the area around Taihu Lake is close to 30℃,during the cyanobacteria outbreak period(July to August),the wind speed is mainly distributed at 2.5-3.0 m/s.During the cyanobacteria recovery and growth period(April to May),the temperature is less than 20℃and the wind speed is between 2.0-3.0 m/s,with the highest occurrence probability of 39.3%,which provides an extremely suitable growth condition for cyanobacteria and makes large-area cyanobacteria bloom more likely to occur in summer.