Contamination Assessment and Source Analysis of Urban Waterways Based on Bayesian and Principal Component Analysis—A Case Study of Fenjiang River

Abstract

Contamination assessment and source analysis of urban waterways are important for the environmental management of water resources. This study applied an improved water quality index (WQI), which was called WQI-DET (water quality index deterioration) to analyze the Fenjiang River’s (Foshan City, South China) water quality monitoring data from 2016 to 2021. Between 2016 and 2021, the Fenjiang River had the highest WQI-DET value in 2016. Since then, the water quality has shown a decreasing trend year by year. Then, through Spearman analysis, it was identified that the chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) are the main factors of water quality deterioration. Moreover a Bayesian model was used to analyze and evaluate the main factors. On this basis, relationships between COD, NH3-N, the natural environment, and human activities were analyzed by principal component analysis. The results showed that NH3-N has been the main factor affecting the water quality in recent years and there were no significant changes in COD and NH3-N during the study period. However, COD and NH3-N showed significant differences in spatial distribution. Meanwhile, human activities contributed 52.3% to the variability in the water quality of the Fenjiang River, and natural factors only 26.8%; factors not considered in this study contributed the remaining 20.9%. Human activities had a more significant impact on the water quality of the Fenjiang River than natural factors.