Temporal and spatial variations in water quality of Changjiang River Basin in Luzhou, China based on multivariate statistical techniques

This study evaluated the spatial and temporal variations of water quality to understand further the water quality in the Changjiang River Basin in Luzhou, China. Data of 16 water quality parameters at nine monitoring stations from 2011 to 2016 were analyzed on the basis of the cluster analysis (CA) and discriminant analysis in multivariate statistical analysis methods, with 612 samples per parameter. Results showed that the CA divided the observation months into three periods according to the similarity of water quality characteristics. Periods 1 (December-May), 2 (July-September), and 3 (June, October, and November) corresponded to the dry, wet, and flat seasons, respectively. The nine sites were divided using space analysis into two groups (A and B), which corresponded to light and moderate pollution, respectively. The important parameters representing temporal and spatial differences were water temperature, flow rate, five-day biochemical oxygen demand, fecal coliform bacteria, electrical conductivity, ammonia nitrogen, oils, fluoride, and arsenic. Optimizing the monitoring frequency or sampling points, strengthening the monitoring of nine important parameters simultaneously, and controlling the pollution of polluted river are suggested on the basis of the results. This study can provide a scientific basis for water quality monitoring and functional zoning of the Luzhou section of the Changjiang River Basin.