Time-series Characteristics and Influencing Factors of pH Value in the Qingfeng Gorge Section of the Jialing River from 2007 to 2017

Based on the survey data of river water quality in the Qingfeng Gorge section, Guangyuan section of the Jialing River, the temporal characteristics of river water pH value in the Qingfeng Gorge section from 2007 to 2017 were analyzed by literature method and statistical method, and explored the causes and influencing factors. The results showed that: 1) The interannual change of the pH value was small in the Qingfeng Gorge, which fluctuated around 8.21 all the year round. The water body was slightly alkaline, showing a downward trend on the whole; 2) In terms of seasonal variation, the pH value in winter and spring was higher than that in summer and autumn, and the mean pH value was spring (8.29) > winter (8.25) > autumn (8.16) > summer (8.14); 3) The weekly variation of pH value was small, with low dispersion and stable change; 4) From the analysis of seasonal variation of pH value, it could be concluded that precipitation was the most significant factor that causeing the change of pH value in the river. There was a significant negative correlation between pH value and DO, CODMN and NH3-N, which indicated that human activities caused the change of pH value of water body to some extent.