Temporal and spatial distribution of ship wastewater generated in the Yangtze River

Artikel i vetenskaplig tidskrift, 2026

With the ongoing expansion of shipping along the Yangtze River, ship-generated wastewater has attracted increasing attention due to its environmental impact. Untreated or inadequately treated shipborne wastewater poses significant threats to aquatic ecosystems through nutrient loading, pathogen introduction, and chemical contamination, yet comprehensive quantification remains lacking to guide pollution control efforts. To support effective monitoring and control strategies, this study presents the first high-resolution quantification of shipborne wastewater—including both greywater and blackwater—across the trunk and branch lines of the Yangtze River. Using Automatic Identification System (AIS) data and a robust wastewater estimation model, the analysis provides a detailed spatial and temporal assessment of wastewater generation patterns. Results indicate that the total amount of wastewater generated by ships operating in the Yangtze River basin in 2022 is 2.01 × 10⁷ m³, in which 1.55 × 10⁷ m³ of wastewater (1.28 × 10⁷ m³ greywater, 2.7 × 10⁶ m³ blackwater) generated in trunk line, and 4.6 × 10⁶ m³ (3.8 × 10⁶ m³ greywater, 8 × 10⁵ m³ blackwater) in the branch lines. Passenger ships account for 31.5% of the total wastewater, while cargo ships account for 19%. Among all vessel types, passenger ships are the largest contributors to wastewater generation across both main and secondary routes. A sensitivity analysis demonstrates that the total wastewater estimate could range from 1.21 × 10⁷ m³ to 3.13 × 10⁷ m³, yet the relative contributions of ship types and spatial hotspots remain robust across all scenarios. Spatiotemporal analysis reveals that the lower reaches of the Yangtze River have the highest wastewater production, underscoring the need for prioritised environmental monitoring in this region. By identifying high-risk zones and quantifying ship specific contributions, these findings provide critical data to inform and optimize the strategic placement of wastewater collection facilities in port areas, supporting more effective pollution management along the Yangtze River.