2018年汉江下游硅藻水华成因分析

针对2018年初春发生于汉江下游的严重硅藻水华事件,根据2018年2～3月水文水质监测数据,从营养盐、水温、流量、河口水位、流速等方面分析了水华发生期间各因子的浮动范围。结果表明,汉江下游氮、磷浓度分别大于1.5、0.1mg/L,水温为8.4～17.7℃,水华发生期间流量大于700m^3/s,水华消退时流量大于1000m^3/s,仙桃与河口水位分别高于、低于历史水华发生年份对应的水位,兴隆库区平均流速为0.15m/s,兴隆下游平均流速为0.44m/s。与历史数据对比,发现2018年汉江下游严重硅藻水华发生的根本原因是氮磷营养盐水平较高和过低的流速条件。研究成果可为汉江下游硅藻水华防治提供参考。

Cause Analysis of Diatom Bloom of Lower Reaches of Hanjiang River in 2018

In view of the serious diatom blooms in the lower reaches of the Hanjiang River in early spring of 2018,based on the monitoring data of hydrology and water quality from February to March of 2018,the varying range of each factor during the blooms was analyzed from the aspects of nutrient concentration,water temperature,discharge,estuarine water level and velocity.The results show that the concentration of nitrogen and phosphorus in the lower reaches of the Hanjiang River is respectively greater than 1.5 mg/L and 0.1 mg/L,the water temperature is 8.4~17.7℃,the discharge is greater than 700 m^3/s during the algal bloom while it is greater than 1000 m^3/s after the algal bloom,and the water level of the Xiantao and estuary is higher than that of the historical blooming years respectively,the average flow velocity in the Xinglong Reservoir is 0.15 m/s,and the average flow in the lower reaches of the Xinglong Reservoir is0.44 m/s.Compared with the historical data,it is found that the root causes of the serious diatom blooms in the lower reaches of the Hanjiang River in 2018 are the high concentrations nitrogen and phosphorus nutrient and low water velocity.The research results can provide reference for the prevention and control of diatom blooms in the lower reaches of the Hanjiang River.