Recovery of Microcystis surface scum following a mixing event: Insights from a tank experiment

Xingqiang Wu, Tiantian Yang, Shanshan Feng, Lin Li, Bangding Xiao, Lirong Song, Assaf Sukenik, Ilia Ostrovsky

Research output: Contribution to journalArticlepeer-review


Cyanobacteria of the genus Microcystis produces surface scum that negatively affects water quality in inland waters. This scum layer can be disintegrated and vertically dispersed by external forces (e.g., wind mixing), followed by reformation of surface scum as buoyant Microcystis colonies migrate upward. However, the recovery dynamics of Microcystis surface scum following a strong mixing event have rarely been studied. Here, we used a tank experiment to investigate the process of Microcystis surface scum recovery after a mixing event with focus on dynamics of colonies of different size classes and their contribution to that process. Microcystis colony size distribution and colony volume concentration was measured using a laser in-situ scattering and transmissometry instrument. The dynamics of Microcystis in the water column and upward colony migration velocity were strongly dependent on colony size. Larger colonies (>180 μm) with fast upward migration rates contributed the most to surface scum formation shortly after turbulence subsided. The contribution of slowly migrating smaller colonies to scum formation was observed over notably longer time. The estimated floating velocities of large colonies ranged 0.15 to 0.46 m h−1 depending on colony size and were 5–15 times higher than those of smaller colonies (~0.03 m h−1). The changes in colony size distribution of Microcystis in the water column reflect the dynamics of surface scum. Analysis of size distribution of Microcystis colonies can be used for better understanding and prediction of Microcystis surface scum development in water bodies.

Original languageEnglish
Article number138727
JournalScience of the Total Environment
StatePublished - 1 Aug 2020
Externally publishedYes

Bibliographical note

Funding Information:
We thank Prof. Enhua Li (Institute of Geodesy and Geophysics, Chinese Academy of Sciences) for kindly providing their LISST 200× instrument for our use, and Prof. Andreas Lorke (University of Koblenz-Landau, Institute for Environmental Sciences) for his comments and the English editing. This work was supported by the Joint NSFC-ISF Research Program, jointly funded by the National Natural Science Foundation of China (grant no. 41561144008 ) and the Israel Science Foundation (grant no. 2033/15 ). This study was also granted by the National Natural Science Foundation of China (grant no. 31870450 & 31670465 ). Xingqiang Wu was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences and the Youth Innovation Promotion Association of the Chinese Academy of Sciences (grant no. 2018373 ). We thank Natalie Kim, PhD, from Liwen Bianji, Edanz Editing China ( ) for editingthe English text of a draft of this manuscript.

Publisher Copyright:
© 2020 Elsevier B.V.


  • Colony size distribution
  • Colony volume concentration
  • Cyanobacterial blooms
  • Microcystis colonies
  • Surface scum recovery
  • Vertical migration velocity

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


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