High frequency variation characteristics of water quality and algae in Meiliang Bay of Taihu Lake in summer and the correlation analysis

Abstract This study aimed to observe the characteristics of water quality and algae in Meiliang bay of Taihu Lake, China, and probe the correlation. The water quality and algae were observed at fixed sites and high frequency (three times per day) for five days. The observation indexes included: (1) water temperature, dissolved oxygen percentage, dissolved oxygen concentration, electrical conductivity, TDS, salinity, pH and ORP. (2) Total nitrogen (TN), total dissolved nitrogen (TDN), total phosphorus (TP), total dissolved phosphorus (TDP), chlorophyll-a content, permanganate index (COD), NO3 −-N, NH4 +-N, and PO4 3-P. Then correlation analysis was conducted between the above indexes and algae growth. The results showed that:(1) The concentration of TN was 1.479±0.152mg/L. The concentration of TP was 0.113± 0.019mg/L. The COD concentration was 4.584±0.549mg/L. (2) A variety of algae were observed in the samples, among which microcystis was the most abundant. The concentration of chlorophyll-a was 28.509±7.421ug/L. (3) Chlorophyll-a content was significantly correlated with TDN, TDP, PO4 3-P (P < 0.001), NH4 +-N, NO3 −-N (P < 0.01), and TP (P < 0.05). Based on above results, we conclude that all the indexes in Meiliang Bay of Taihu Lake are in the normal range, indicating that the effects of ecological management is obvious. However, the water environment is still suitable for the growth of algae, especially cyanobacteria, so there is still potential danger of cyanobacteria bloom. It is necessary to strengthen monitoring and take timely countermeasures.