Dynamic analysis of port water quality: insights from Zhanjiang Port, China

Abstract

The management of port water quality is crucial to marine ecological balance and has been of great concern. In the present study, the water quality monitoring data in Zhanjiang Port from 2015 to 2022 were utilized to analyze the spatiotemporal characteristics and reveal the correlation between different parameters. The structural equation model has been applied to profile the dominant factors of water quality level. The results showed that the port water quality was generally worse in summer and better in winter. Variations in total phosphorus (TP), chemical oxygen demand (COD) and total nitrogen (TN) content directly led to water quality changes in Zhanjiang Port, where an increase in TP content resulted in a significant decrease in water quality level (path coefficient is 2.87). Permanganate index (CODMn) and ammonia nitrogen content indirectly affected the water quality level, while changes in pH and dissolved oxygen (DO) showed no impact. Ammonia nitrogen, pH and DO contents were significantly associated with TP. Human activities and industrial production were identified as the main sources of water quality pollution. The increasing trend of certain water quality parameters highlights the urgency of implementing timely measures to improve water quality conditions in Zhanjiang Bay, China.