过氧化钙对武汉东湖浮游植物群落及水环境的影响

为探讨过氧化钙作为化学除藻剂对浮游植物群落和水质的影响，于2020年10月采集武汉东湖原水，在深度为2m的水柱中使用不同剂量的过氧化钙进行处理。结果显示：40 mg/L、60 mg/L、80 mg/L的过氧化钙在东湖原水中释放的过氧化氢最高浓度分别为17.04±0.82mg/L、22.21±0.81 mg/L和31.67±2.47mg/L；水柱0~1.0 m水层的过氧化氢含量显著高于1.0-2.0m水层，持续释放时间可达36h~48h；过氧化钙的使用能显著减少底层水体的正磷酸盐含量；同时，过氧化钙在处理12h后可显著降低水柱中叶绿素 a含量和蓝藻的相对丰度（P<0.05），同时提高了绿藻相对丰度28.06%，将硅藻相对丰度提高了27.25%，改变浮游植物群落的物种优势度，具有选择性杀灭蓝藻的效果。本研究可为过氧化钙在蓝藻水华处置、水体富营养化治理等方面的应用提供参考依据。

Effects of Calcium Peroxide on the Phytoplankton Community and Water Quality of Donghu Lake, Wuhan

Overgrowth of phytoplankton, particularly cyanobacteria, seriously impairs water quality and is frequently removed with chemicals. Calcium peroxide is an environment friendly and highly effective strong oxidant that slowly releases hydrogen peroxide to water. Although calcium peroxide is widely used for substrate improvement and oxygenating aquaculture ponds, little research has been conducted on its effects on water quality and phytoplankton. In this study, we investigated the effects of calcium peroxide on the phytoplankton community and water quality of Donghu Lake, Wuhan, aiming to provide guidance for the application of calcium peroxide for treating cyanobacteria blooms and managing eutrophication. Water was collected from Donghu Lake on October 27, 2020 and placed in 2.0 m cylindrical containers, with three calcium peroxide treatments (40, 60, 80 mg/L) and a control group. Twenty-four hours before and after treatment, water samples from each treatment were collected for quantitative and qualitative determination of phytoplankton and water quality parameters. The hydrogen peroxide concentration was determined by the I3- method, orthophosphate by the phosphomolybdenum blue-ascorbic acid method and chlorophyll-a by the acetone extraction method. The highest concentrations of hydrogen peroxide released in the calcium peroxide treatments (40 mg/L, 60 mg/L and 80 mg/L) were, respectively, (17.04±0.82) mg/L, (22.21±0.81) mg/L and (31.67±2.47) mg/L. Release of hydrogen peroxide lasted 36-48 h in all calcium peroxide treatments, and the hydrogen peroxide content at a water depth of 0-1.0 m was higher than at 1.0-2.0 m. Calcium peroxide significantly reduced the orthophosphate content of bottom water as well as the chlorophyll-a concentration and the relative abundance of cyanobacteria in all treatments (P<0.05). The relative abundances of chlorophyta and diatoms increased, consequently altering the dominant phytoplankton species. Calcium peroxide effectively improves water quality by reducing phosphorus, restructuring the phytoplankton community and reducing the biomass of cyanobacteria.