2024年汉江中下游硅藻水华演变分析

Analysis of the Evolution of Diatom Blooms in the Middle and Lower Hanjiang River in 2024

摘要: 2023年12月1日~2024年3月31日通过自动监测和现场调查相结合，开展汉江中下游硅藻水华演变分析研究。结果显示，汉江硅藻水华优势种为冠盘藻属；支流唐白河汇入后，冠盘藻属数量从1.30 × 10⁴ cells/L增长至4.60 × 10⁵ cells/L，占比达到71.5%，浮游植物总量从1.10 × 10⁵ cells/L增长至6.43 × 10⁵ cells/L，水华级别从I级进入II级；当冠盘藻属占比大于50%，水温低于12℃，气温短期内快速上升时，7天可从水华I级进入II~III级，冠盘藻属占比、水温和气温可作为水华预警参数；叶绿素a和浮游植物数量变化显著相关，可以作为评判水华应急调度效果的指示参数，调节流量可以快速消除水华影响，1月和3月两次生态水量调度，均在7天内将叶绿素a降至10 μg/L以下。研究揭示了汉江中下游硅藻水华影响因子，为揭示硅藻水华发生机理，开展硅藻水华防治提供理论支持。

Abstract: From December 1, 2023 to March 31, 2024, we conducted automatic monitoring and on-site investigations to study the diatom blooms and identification of the advantage species in the Middle and Lower Hanjiang River. The results of our research indicated that the dominant species of diatom blooms were Stephanodiscus sp. After the inflow of Tangbai River, a tributary, the diatom blooms level entered from level I to level II. The number of Stephanodiscus sp. increased from 1.30 × 10⁴ cells/L to 4.60 × 10⁵ cells/L, accounting for 71.5%, and the total amount of phytoplankton increased from 1.10 × 10⁵ cells/L to 6.43 × 10⁵ cells/L. The diatom blooms could enter from level I to level II~III within 7 days, when the proportion of Stephanodiscus sp. was greater than 50%, the water temperature is below 12˚C and the temperature rises rapidly. The proportion of Stephanodiscus sp., water temperature and temperature could be used as early warning parameters for diatom blooms. Chlorophyll a and phytoplankton quantity changes are similar, which can be used as an indicator parameter to judge the effect of emergency dispatching of diatom blooms. Adjusting the flow can quickly eliminate the impact of diatom blooms. The two ecological water dispatching in January and March both reduced chlorophyll a to below 10 μg/L within 7 days. Our study unveils the influencing factors of the diatom blooms in the Middle and Lower Hanjiang River, thus providing essential theoretical support for understanding diatom blooms mechanisms and developing prevention and control strategies.