Abstract: To understand the spatial and temporal distribution of microcystin (MC) concentrations in the reservoir, water samples were monthly collected in Baihua Reservoir, Guizhou Plateau from June 2017 to May 2018. The concentrations of MC (including two isomers of MC-RR and MC-LR), total phytoplankton abundance, cyanobacterial abundance, chlorophyll-a (Chla) concentration, nutritive salt concentration, water temperature and transparency were analyzed. The results showed that the concentrations of MC-RR and MC-LR ranged from 0.048 to 0.681 μg·L^-1 and from 0.046 to 0.964 μg·L^-1 respectively in the Baihua Reservoir. MC-RR occurred at high temperature while MC-LR occurred at low temperature. The Huaqiao sampling site had the highest number of detection and the highest concentration of MC, reaching 0.964 μg·L^-1, which did not exceed the limited value of 1.0 μg·L^-1; while dam sampling site was in the opposite. The MC-RR concentration was positively correlated with water temperature and ammonium nitrogen (NH₄⁺-N) concentration, and MC-LR was positively correlated with NH₄⁺-N concentration, nitrite nitrogen (NO₂^--N) concentration, and pH. Meanwhile, MC-RR concentration was significantly positively correlated with the abundance of Pseudanabaena limnetica and Anabaena circinalis and positively correlated with Chroococcussp. abundance, while MC-LR concentration was not significantly correlated with phytoplankton abundance.

Key words: landscaping trees, adsorption ability, PM_2.5, leaf surface morphology, atomic force microscopy (AFM).