Method for screening water physicochemical parameters to calculate water quality index based on these parameters' correlation with water microbiota.

Water quality index (WQI) plays a crucial role in guiding water resource management. However, WQI calculation methods are not uniform, especially the selection of water parameters and the weighting given to each water parameter (P). To optimize WQI calculation, 132 water samples from seven rivers and from Chaohu Lake (33 sampling sites in Chaohu Lake Basin) in four seasons were collected, and the water parameters and microbiota composition were analyzed using high-throughput sequencing of 16 S rDNA. The correlation coefficient R between water parameters and microbiota composition using redundancy analysis with the Monte Carlo method were calculated, and the water parameters that significantly correlated with the microbiota composition were selected to calculate WQI. The results showed that TP, COD, DO, and Chl a correlated significantly with water microbiota composition. WQI calculated by substituting R for P was more consistent with the similarity between the microbiota compositions. WQI calculated using TP, COD, and DO was consistent with WQI. The results of WQI and WQI were more consistent than those of WQI and WQI. These results imply that using R instead of P could help obtain a more stable WQI that could better reflect the biological characteristics of the Chaohu Lake Basin.